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Sample records for anode buffer layer

  1. Effects of Anodic Buffer Layer in Top-Illuminated Organic Solar Cell with Silver Electrodes

    Directory of Open Access Journals (Sweden)

    Tien-Lung Chiu

    2013-01-01

    Full Text Available An efficient ITO-free top-illuminated organic photovoltaic (TOPV based on small molecular planar heterojunction was achieved by spinning a buffer layer of poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS, on the Ag-AgOx anode. The PEDOT:PSS thin film separates the active layer far from the Ag anode to prevent metal quenching and redistributes the strong internal optical field toward dissociated interface. The thickness and morphology of this anodic buffer layer are the key factors in determining device performances. The uniform buffer layer contributes a large short-circuit current and open-circuit voltage, benefiting the final power conversion efficiency (PCE. The TOPV device with an optimal PEDOT:PSS thickness of about 30 nm on Ag-AgOx anode exhibits the maximum PCE of 1.49%. It appreciates a 1.37-fold enhancement in PCE over that of TOPV device without buffer layer.

  2. Simple solution-processed CuOX as anode buffer layer for efficient organic solar cells

    International Nuclear Information System (INIS)

    Shen, Wenfei; Yang, Chunpeng; Bao, Xichang; Sun, Liang; Wang, Ning; Tang, Jianguo; Chen, Weichao; Yang, Renqiang

    2015-01-01

    Graphical abstract: - Highlights: • Simple solution-processed CuO X hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuO X as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuO X anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuO X was the composite of CuO and Cu 2 O. The CuO X modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuO X layer was optimized by varying the thickness of CuO X films through changing solution concentration. With P3HT:PC 61 BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuO X anode buffer layer, compared with that of PEDOT:PSS layer. The CuO X layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC 71 BM as the active layer. The long-term stability of CuO X device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuO X film can act as an efficient anode buffer layer for high-efficiency OSCs

  3. Improved Reliability of Small Molecule Organic Solar Cells by Double Anode Buffer Layers

    Directory of Open Access Journals (Sweden)

    Pao-Hsun Huang

    2014-01-01

    Full Text Available An optimized hybrid planar heterojunction (PHJ of small molecule organic solar cells (SM-OSCs based on copper phthalocyanine (CuPc as donor and fullerene (C60 as acceptor was fabricated, which obviously enhanced the performance of device by sequentially using both MoO3 and pentacene as double anode buffer layers (ABL, also known as hole extraction layer (HEL. A series of the vacuum-deposited ABL, acting as an electron and exciton blocking layer, were examined for their characteristics in SM-OSCs. The performance and reliability were compared between conventional ITO/ABL/CuPc/C60/BCP/Ag cells and the new ITO/double ABL/CuPc/C60/BCP/Ag cells. The effect on the electrical properties of these materials was also investigated to obtain the optimal thickness of ABL. The comparison shows that the modified cell has an enhanced reliability compared to traditional cells. The improvement of lifetime was attributed to the idea of double layers to prevent humidity and oxygen from diffusing into the active layer. We demonstrated that the interfacial extraction layers are necessary to avoid degradation of device. That is to say, in normal temperature and pressure, a new avenue for the device within double buffer layers has exhibited the highest values of open circuit voltage (Voc, fill factor (FF, and lifetime in this work compared to monolayer of ABL.

  4. Effects of the buffer layer inserted between the transparent conductive oxide anode and the organic electron donor

    Energy Technology Data Exchange (ETDEWEB)

    Godoy, A.; Kouskoussa, B.; Benchouk, K.; Khelil, A. [Facultad Ciencias de la Salud, Universidad Diego Portales, Ejercito 141, Santiago de Chile (Chile); Cattin, L.; Soto, G.M. [Universite de Nantes, Nantes Atlantique Universites, Institut des Materiaux Jean Rouxel (IMN)-CNRS, Faculte des Sciences et Techniques, 2 rue de la Houssiniere, BP 92208, Nantes F-44000 (France); Toumi, L. [LPCM2E, Universite d' Oran Es-Senia, LPCM2E (Algeria); Diaz, F.R.; del Valle, M.A. [Laboratorio de Polimeros, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Casilla 306, Correo 22, Santiago (Chile); Morsli, M.; Bernede, J.C. [Universite de Nantes, Nantes Atlantique Universites, LAMP, Faculte des Sciences et Techniques, 2 rue de la Houssiniere, BP 92208, Nantes F-44000 (France)

    2010-04-15

    In optoelectronic devices, the work function of the transparent conductive oxide, which is used as anode, does not match well the highest occupied molecular orbital of the organic material, which induces the formation of a barrier opposed to hole exchange at this interface. Therefore a thin buffer layer is often used to achieve good matching of the band structure at the interface. From experimental results it can be deduced that the main effects of the buffer layer consist in a better matching of the band structure at the interface anode/organic material and in a more homogeneous organic layer growth. We show that, whatever the nature of the buffer layer-metal, oxide, organic material - the classical Schottky-Mott model allows to anticipate, at least roughly, the behaviour of the contact, even if some dipole effect are often present. A good correlation between the ''metal/buffer layer'' work function and the barrier {phi}{sub b} for hole exchange at anode/organic electron donor interfaces is obtained, as expected by the model. (author)

  5. Simple solution-processed CuO{sub X} as anode buffer layer for efficient organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Wenfei [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Yang, Chunpeng [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Bao, Xichang, E-mail: baoxc@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Sun, Liang; Wang, Ning [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Tang, Jianguo [Institute of Hybrid Materials, The Growing Base for State Key Laboratory, Qingdao University, 308 Ningxia Road, Qingdao 266071 (China); Chen, Weichao [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China); Yang, Renqiang, E-mail: yangrq@qibebt.ac.cn [CAS Key Laboratory of Bio-based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, 189 Songling Road, Qingdao 266101 (China)

    2015-10-15

    Graphical abstract: - Highlights: • Simple solution-processed CuO{sub X} hole transport layer for efficient organic solar cell. • Good photovoltaic performances as hole transport layer in OSCs with P3HT and PBDTTT-C as donor materials. • The device with CuO{sub X} as hole transport layer shows great improved stability compared with that of device with PEDOT:PSS as hole transport layer. - Abstract: A simple, solution-processed ultrathin CuO{sub X} anode buffer layer was fabricated for high performance organic solar cells (OSCs). XPS measurement demonstrated that the CuO{sub X} was the composite of CuO and Cu{sub 2}O. The CuO{sub X} modified ITO glass exhibit a better surface contact with the active layer. The photovoltaic performance of the devices with CuO{sub X} layer was optimized by varying the thickness of CuO{sub X} films through changing solution concentration. With P3HT:PC{sub 61}BM as the active layer, we demonstrated an enhanced PCE of 4.14% with CuO{sub X} anode buffer layer, compared with that of PEDOT:PSS layer. The CuO{sub X} layer also exhibits efficient photovoltaic performance in devices with PBDTTT-C:PC{sub 71}BM as the active layer. The long-term stability of CuO{sub X} device is better than that of PEDOT:PSS device. The results indicate that the easy solution-processed CuO{sub X} film can act as an efficient anode buffer layer for high-efficiency OSCs.

  6. Ultra-thin fluoropolymer buffer layer as an anode stabilizer of organic light emitting devices

    International Nuclear Information System (INIS)

    Yang, Nam Chul; Lee, Jaeho; Song, Myung-Won; Ahn, Nari; Kim, Mu-Hyun; Lee, Songtaek; Chin, Byung Doo

    2007-01-01

    We have investigated the effect of thin fluoro-acrylic polymer as an anode stabilizer on the lifetime of an organic light emitting device (OLED). Surface chemical properties of commercial fluoropolymer, FC-722 (Fluorad(TM) of 3M), on indium-tin oxide (ITO) were characterized by x-ray photoemission spectroscopy. An OLED with 1 nm thick fluoropolymeric film showed identical brightness and efficiency behaviour and improved operational stability compared with the reference device with UV-O 3 treated ITO. The improvement in the lifetime was accompanied by the suppression of the voltage increase at the initial stage of constant-current driving, which can be attributed to the action of the FC-722 layer by smoothing the ITO surface. Fluoropolymer coating, therefore, improves the lifetime of the small molecular OLED by the simple and reliable anode-stabilizing process

  7. Solution processed transition metal oxide anode buffer layers for efficiency and stability enhancement of polymer solar cells

    Science.gov (United States)

    Ameen, M. Yoosuf; Shamjid, P.; Abhijith, T.; Reddy, V. S.

    2018-01-01

    Polymer solar cells were fabricated with solution-processed transition metal oxides, MoO3 and V2O5 as anode buffer layers (ABLs). The optimized device with V2O5 ABL exhibited considerably higher power conversion efficiency (PCE) compared to the devices based on MoO3 and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) ABLs. The space charge limited current measurements and impedance spectroscopy results of hole-only devices revealed that V2O5 provided a very low charge transfer resistance and high hole mobility, facilitating efficient hole transfer from the active layer to the ITO anode. More importantly, incorporation of V2O5 as ABL resulted in substantial improvement in device stability compared to MoO3 and PEDOT:PSS based devices. Unencapsulated PEDOT:PSS-based devices stored at a relative humidity of 45% have shown complete failure within 96 h. Whereas, MoO3 and V2O5 based devices stored in similar conditions retained 22% and 80% of their initial PCEs after 96 h. Significantly higher stability of the V2O5-based device is ascribed to the reduction in degradation of the anode/active layer interface, as evident from the electrical measurements.

  8. Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells

    OpenAIRE

    Xu, Binrui; Gopalan, Sai-Anand; Gopalan, Anantha-Iyengar; Muthuchamy, Nallal; Lee, Kwang-Pill; Lee, Jae-Sung; Jiang, Yu; Lee, Sang-Won; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Kwon, Jin-Beon; Bae, Jin-Hyuk; Kang, Shin-Won

    2017-01-01

    Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified ...

  9. Finding the lost open-circuit voltage in polymer solar cells by UV-ozone treatment of the nickel acetate anode buffer layer.

    Science.gov (United States)

    Wang, Fuzhi; Sun, Gang; Li, Cong; Liu, Jiyan; Hu, Siqian; Zheng, Hua; Tan, Zhan'ao; Li, Yongfang

    2014-06-25

    Efficient polymer solar cells (PSCs) with enhanced open-circuit voltage (Voc) are fabricated by introducing solution-processed and UV-ozone (UVO)-treated nickel acetate (O-NiAc) as an anode buffer layer. According to X-ray photoelectron spectroscopy data, NiAc partially decomposed to NiOOH during the UVO treatment. NiOOH is a dipole species, which leads to an increase in the work function (as confirmed by ultraviolet photoemission spectroscopy), thus benefitting the formation of ohmic contact between the anode and photoactive layer and leading to increased Voc. In addition, the UVO treatment improves the wettability between the substrate and solvent of the active layer, which facilitates the formation of an upper photoactive layer with better morphology. Further, the O-NiAc layer can decrease the series resistance (Rs) and increase the parallel resistance (Rp) of the devices, inducing enhanced Voc in comparison with the as-prepared NiAc-buffered control devices without UVO treatment. For PSCs based on the P3HT:PCBM system, Voc increases from 0.50 to 0.60 V after the NiAc buffer layer undergoes UVO treatment. Similarly, in the P3HT:ICBA system, the Voc value of the device with a UVO-treated NiAc buffer layer increases from 0.78 to 0.88 V, showing an enhanced power conversion efficiency of 6.64%.

  10. Simple O2 Plasma-Processed V2O5 as an Anode Buffer Layer for High-Performance Polymer Solar Cells

    DEFF Research Database (Denmark)

    Bao, Xichang; Zhu, Qianqian; Wang, Ting

    2015-01-01

    A simple O2 plasma processing method for preparation of a vanadium oxide (V2O5) anode buffer layer on indium tin oxide (ITO)-coated glass for polymer solar cells (PSCs) is reported. The V2O5 layer with high transmittance and good electrical and interfacial properties was prepared by spin coating...... a vanadium(V) triisopropoxide oxide alcohol solution on ITO and then O2 plasma treatment for 10 min [V2O5 (O2 plasma)]. PSCs based on P3HT:PC61BM and PBDTTT-C:PC71BM using V2O5 (O2 plasma) as an anode buffer layer show high power conversion efficiencies (PCEs) of 4.47 and 7.54%, respectively, under...... the illumination of AM 1.5G (100 mW/cm2). Compared to that of the control device with PBDTTT-C:PC71BM as the active layer and PEDOT:PSS (PCE of 6.52%) and thermally annealed V2O5 (PCE of 6.27%) as the anode buffer layer, the PCE was improved by 15.6 and 20.2%, respectively, after the introduction of a V2O5 (O2...

  11. Inverted bulk-heterojunction organic solar cells with the transfer-printed anodes and low-temperature-processed ultrathin buffer layers

    Science.gov (United States)

    Itoh, Eiji; Sakai, Shota; Fukuda, Katsutoshi

    2018-03-01

    We studied the effects of a hole buffer layer [molybdenum oxide (MoO3) and natural copper oxide layer] and a low-temperature-processed electron buffer layer on the performance of inverted bulk-heterojunction organic solar cells in a device consisting of indium-tin oxide (ITO)/poly(ethylene imine) (PEI)/titanium oxide nanosheet (TiO-NS)/poly(3-hexylthiopnehe) (P3HT):phenyl-C61-butyric acid methylester (PCBM)/oxide/anode (Ag or Cu). The insertion of ultrathin TiO-NS (˜1 nm) and oxide hole buffer layers improved the open circuit voltage V OC, fill factor, and rectification properties owing to the effective hole blocking and electron transport properties of ultrathin TiO-NS, and to the enhanced work function difference between TiO-NS and the oxide hole buffer layer. The insertion of the TiO-NS contributed to the reduction in the potential barrier at the ITO/PEI/TiO-NS/active layer interface for electrons, and the insertion of the oxide hole buffer layer contributed to the reduction in the potential barrier for holes. The marked increase in the capacitance under positive biasing in the capacitance-voltage characteristics revealed that the combination of TiO-NS and MoO3 buffer layers contributes to the selective transport of electrons and holes, and blocks counter carriers at the active layer/oxide interface. The natural oxide layer of the copper electrode also acts as a hole buffer layer owing to the increase in the work function of the Cu surface in the inverted cells. The performance of the cell with evaporated MoO3 and Cu layers that were transfer-printed to the active layer was almost comparable to that of the cell with MoO3 and Ag layers directly evaporated onto the active layer. We also demonstrated comparable device performance in the cell with all-printed MoO3 and low-temperature-processed silver nanoparticles as an anode.

  12. Stability enhancement of P3HT:PCBM polymer solar cells using thermally evaporated MoO3 anode buffer layer

    Science.gov (United States)

    Ameen, M. Yoosuf; Shamjid, P.; Abhijith, T.; Radhakrishnan, Thulasi; Reddy, V. S.

    2018-02-01

    Polymer solar cells have been fabricated with thermally evaporated MoO3 as anode buffer layer (ABL). The stability of MoO3 and PEDOT:PSS based devices was examined under different test conditions. The MoO3 based device exhibited a slightly better efficiency and significantly higher stability compared to PEDOT:PSS based device. At a relative humidity of 45% the unencapsulated PEDOT:PSS based device degraded completely within 96 h. On the other hand, MoO3 based device retained more than 60% of its initial efficiency after 96 h. The reason behind stability enhancement was investigated by measuring time-evolution of reflectance and hole-current. Experimental results revealed that the stability enhancement for MoO3 based device originates from the reduction in degradation of anode/active layer interface.

  13. Influence of the highest occupied molecular orbital energy level of the donor material on the effectiveness of the anode buffer layer in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bernede, J.C.; Leriche, P.; Roncali, J. [UNAM, Moltech Anjou, CNRS, UMR 6200, Groupe Systemes Conjugues Lineaires, Angers (France); Cattin, L. [UNAM, Institut Jean Rouxel (IMN), UMR 6502, Nantes (France); Djobo, S. Ouro; Morsli, M. [Universite de Nantes, LAMP, EA 3825, Faculte des Sciences et des Techniques, Nantes (France); Kanth, S.R.B.; Patil, S. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore (India); Godoy, A. [University San Sebastian, Prog. Bachiller, Cs. Biolog. Qcas, Bellavista (Chile); Diaz, F.R.; Del Valle, M.A. [University Catolica Chile, Fac. Quimica, Santiago (Chile)

    2011-08-15

    Efficiency of organic photovoltaic cells based on organic electron donor/organic electron acceptor junctions can be strongly improved when the transparent conductive Anode is coated with a Buffer Layer (ABL). Here, the effects of a metal (gold) or oxide (molybdenum oxide) ABL are reported, as a function of the Highest Occupied Molecular Orbital (HOMO) of different electron donors. The results indicate that a good matching between the work function of the anode and the highest occupied molecular orbital of the donor material is the major factor limiting the hole transfer efficiency. Indeed, gold is efficient as ABL only when the HOMO of the organic donor is close to its work function {phi}{sub Au}. Therefore we show that the MoO{sub 3} oxide has a wider field of application as ABL than gold. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells.

    Science.gov (United States)

    Xu, Binrui; Gopalan, Sai-Anand; Gopalan, Anantha-Iyengar; Muthuchamy, Nallal; Lee, Kwang-Pill; Lee, Jae-Sung; Jiang, Yu; Lee, Sang-Won; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Kwon, Jin-Beom; Bae, Jin-Hyuk; Kang, Shin-Won

    2017-03-24

    Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances. The electrical conductivity of PEDOT:PSS@DOH films was markedly improved compared with that of PEDOT:PSS. The PEDOT:PSS@DOH film exhibited excellent optical characteristics, appropriate work function alignment, and good surface properties in BHJ-PSCs. When a poly(3-hexylthiohpene):[6,6]-phenyl C 61 -butyric acid methyl ester blend system was applied as the photoactive layer, the power conversion efficiency of the resulting PSCs with PEDOT:PSS@DOH(1.0%) reached 3.49%, outperforming pristine PEDOT:PSS, exhibiting a power conversion enhancement of 20%. The device fabricated using PEDOT:PSS@DOH (1.0 wt%) also exhibited improved thermal and air stability. Our results also confirm that DOH, a basic pyridine derivative, facilitates adequate hydrogen bonding interactions with the sulfonic acid groups of PSS, induces the conformational transformation of PEDOT chains and contributes to the phase separation between PEDOT and PSS chains.

  15. Doped LZO buffer layers for laminated conductors

    Science.gov (United States)

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2010-03-23

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  16. Study of buffer layer thickness on bulk heterojunction solar cell.

    Science.gov (United States)

    Noh, Seunguk; Suman, C K; Lee, Donggu; Kim, Seohee; Lee, Changhee

    2010-10-01

    We studied the effect of the buffer layer (molybdenum-oxide (MoO3)) thickness on the performance of organic solar cell based on blends of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester fullerene derivative (PCBM). The thickness of MoO3 was varied from 1 nm to 30 nm for optimization of device performance. The photocurrent-voltage and impedance spectroscopy were measured under dark and AM1.5G solar simulated illumination of 100 mW/cm2 for exploring the role of the buffer layer thickness on carrier collection at an anode. The MoO3 thickness of the optimized device (efficiency approximately 3.7%) was found to be in the range of 5 approximately 10 nm. The short-circuit current and the shunt resistance decrease gradually for thicker MoO3 layer over 5 nm. The device can be modeled as the combination of three RC parallel circuits (each one for the active layer, buffer layer and interface between the buffer layer and the active layer) in series with contact resistance (Rs approximately 60 ohm).

  17. Atomic Layer Deposition of SnO2 on MXene for Li-Ion Battery Anodes

    KAUST Repository

    Ahmed, Bilal

    2017-02-24

    In this report, we show that oxide battery anodes can be grown on two-dimensional titanium carbide sheets (MXenes) by atomic layer deposition. Using this approach, we have fabricated a composite SnO2/MXene anode for Li-ion battery applications. The SnO2/MXene anode exploits the high Li-ion capacity offered by SnO2, while maintaining the structural and mechanical integrity by the conductive MXene platform. The atomic layer deposition (ALD) conditions used to deposit SnO2 on MXene terminated with oxygen, fluorine, and hydroxyl-groups were found to be critical for preventing MXene degradation during ALD. We demonstrate that SnO2/MXene electrodes exhibit excellent electrochemical performance as Li-ion battery anodes, where conductive MXene sheets act to buffer the volume changes associated with lithiation and delithiation of SnO2. The cyclic performance of the anodes is further improved by depositing a very thin passivation layer of HfO2, in the same ALD reactor, on the SnO2/MXene anode. This is shown by high-resolution transmission electron microscopy to also improve the structural integrity of SnO2 anode during cycling. The HfO2 coated SnO2/MXene electrodes demonstrate a stable specific capacity of 843 mAh/g when used as Li-ion battery anodes.

  18. Back contact buffer layer for thin-film solar cells

    Science.gov (United States)

    Compaan, Alvin D.; Plotnikov, Victor V.

    2014-09-09

    A photovoltaic cell structure is disclosed that includes a buffer/passivation layer at a CdTe/Back contact interface. The buffer/passivation layer is formed from the same material that forms the n-type semiconductor active layer. In one embodiment, the buffer layer and the n-type semiconductor active layer are formed from cadmium sulfide (CdS). A method of forming a photovoltaic cell includes the step of forming the semiconductor active layers and the buffer/passivation layer within the same deposition chamber and using the same material source.

  19. Enhancing the Efficiency of Polymer Solar Cells by Modifying Buffer Layer with N,N-Dimethylacetamide

    Directory of Open Access Journals (Sweden)

    Shaopeng Yang

    2014-01-01

    Full Text Available We modified the PEDOT:PSS anode buffer layer in P3HT:PCBM bulk heterojunction polymer solar cells by spin-coating the solvent N,N-dimethylacetamide (DMAC. This modification significantly enhanced the efficiency of the ITO/PEDOT:PSS/DMAC/P3HT:PCBM/LiF/Al solar cells. The DMAC-treated device spin-coated at 3000 rpm exhibited a power conversion efficiency (PCE of 3.74%, a 59% improvement over that of an untreated cell. To study the mechanism of improving the conversion efficiency, we characterized many parameters, including the light and dark I-V curves, external quantum efficiency, active layer absorption spectrum, transmission spectrum of ITO:PEDOTPSS, PEDOT:PSS surface morphology, and electrical conductivity. Modifying the PEDOT:PSS film increased conductivity, making it more conducive to hole extraction and collection. Our findings suggest that modifying the anode buffer layer can improve photoelectric conversion efficiency.

  20. Buffer layers for REBCO films for use in superconducting devices

    Science.gov (United States)

    Goyal, Amit; Wee, Sung-Hun

    2014-06-10

    A superconducting article includes a substrate having a biaxially textured surface. A biaxially textured buffer layer, which can be a cap layer, is supported by the substrate. The buffer layer includes a double perovskite of the formula A.sub.2B'B''O.sub.6, where A is rare earth or alkaline earth metal and B' and B'' are different transition metal cations. A biaxially textured superconductor layer is deposited so as to be supported by the buffer layer. A method of making a superconducting article is also disclosed.

  1. Methods for improved growth of group III nitride buffer layers

    Science.gov (United States)

    Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

    2014-07-15

    Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphology of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).

  2. Low cost fuel cell diffusion layer configured for optimized anode water management

    Science.gov (United States)

    Owejan, Jon P; Nicotera, Paul D; Mench, Matthew M; Evans, Robert E

    2013-08-27

    A fuel cell comprises a cathode gas diffusion layer, a cathode catalyst layer, an anode gas diffusion layer, an anode catalyst layer and an electrolyte. The diffusion resistance of the anode gas diffusion layer when operated with anode fuel is higher than the diffusion resistance of the cathode gas diffusion layer. The anode gas diffusion layer may comprise filler particles having in-plane platelet geometries and be made of lower cost materials and manufacturing processes than currently available commercial carbon fiber substrates. The diffusion resistance difference between the anode gas diffusion layer and the cathode gas diffusion layer may allow for passive water balance control.

  3. Spark protection layers for CMOS pixel anode chips in MPGDs

    NARCIS (Netherlands)

    Bilevych, Y.; Bilevych, Y.; Blanco Carballo, V.M.; Chefdeville, M.A.; Colas, P.; Delagnes, E.; Fransen, M.; van der Graaff, H.; Koppert, W.J.C.; Melai, J.; Salm, Cora; Schmitz, Jurriaan; Timmermans, J.; Timmermans, J.; Wyrsch, N.

    2011-01-01

    In this work we have investigated the functioning of high resistivity amorphous silicon and silicon-rich nitride layers as a protection against discharges in Micro-Patterned Gaseous Detectors (MPGDs).When the anode is protected by a high resistivity layer, discharge signals are limited in charge. A

  4. Reducing interface recombination for Cu(In,Ga)Se2 by atomic layer deposited buffer layers

    International Nuclear Information System (INIS)

    Hultqvist, Adam; Bent, Stacey F.; Li, Jian V.; Kuciauskas, Darius; Dippo, Patricia; Contreras, Miguel A.; Levi, Dean H.

    2015-01-01

    Partial CuInGaSe 2 (CIGS) solar cell stacks with different atomic layer deposited buffer layers and pretreatments were analyzed by photoluminescence (PL) and capacitance voltage (CV) measurements to investigate the buffer layer/CIGS interface. Atomic layer deposited ZnS, ZnO, and SnO x buffer layers were compared with chemical bath deposited CdS buffer layers. Band bending, charge density, and interface state density were extracted from the CV measurement using an analysis technique new to CIGS. The surface recombination velocity calculated from the density of interface traps for a ZnS/CIGS stack shows a remarkably low value of 810 cm/s, approaching the range of single crystalline II–VI systems. Both the PL spectra and its lifetime depend on the buffer layer; thus, these measurements are not only sensitive to the absorber but also to the absorber/buffer layer system. Pretreatment of the CIGS prior to the buffer layer deposition plays a significant role on the electrical properties for the same buffer layer/CIGS stack, further illuminating the importance of good interface formation. Finally, ZnS is found to be the best performing buffer layer in this study, especially if the CIGS surface is pretreated with potassium cyanide

  5. Rare earth zirconium oxide buffer layers on metal substrates

    Science.gov (United States)

    Williams, Robert K.; Paranthaman, Mariappan; Chirayil, Thomas G.; Lee, Dominic F.; Goyal, Amit; Feenstra, Roeland

    2001-01-01

    A laminate article comprises a substrate and a biaxially textured (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer over the substrate, wherein 0layer can be deposited using sol-gel or metal-organic decomposition. The laminate article can include a layer of YBCO over the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. A layer of CeO.sub.2 between the YBCO layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer can also be include. Further included can be a layer of YSZ between the CeO.sub.2 layer and the (RE.sub.x A.sub.(1-x)).sub.2 O.sub.2-(x/2) buffer layer. The substrate can be a biaxially textured metal, such as nickel. A method of forming the laminate article is also disclosed.

  6. Surface plasmon enhanced organic solar cells with a MoO3 buffer layer.

    Science.gov (United States)

    Su, Zisheng; Wang, Lidan; Li, Yantao; Zhang, Guang; Zhao, Haifeng; Yang, Haigui; Ma, Yuejia; Chu, Bei; Li, Wenlian

    2013-12-26

    High-efficiency surface plasmon enhanced 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane:C70 small molecular bulk heterojunction organic solar cells with a MoO3 anode buffer layer have been demonstrated. The optimized device based on thermal evaporated Ag nanoparticles (NPs) shows a power conversion efficiency of 5.42%, which is 17% higher than the reference device. The improvement is attributed to both the enhanced conductivity and increased absorption due to the near-field enhancement of the localized surface plasmon resonance of Ag NPs.

  7. Silver buffer layers for YBCO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Azoulay, J. [Tel Aviv Univ. (Israel). Center for Technol. Education Holon

    1999-09-01

    A simple economical conventional vacuum system was used for evaporation of YBCO thin films on as-deposited unbuffered Ag layers on MgO substrates. The subsequent heat treatment was carried out in low oxygen partial pressure at a relative low temperature and short dwelling time. The films thus obtained were characterized for electrical properties using dc four probe electrical measurements and inspected for structural properties and chemical composition by scanning electron microscopy (SEM). (orig.)

  8. Conductive and robust nitride buffer layers on biaxially textured substrates

    Science.gov (United States)

    Sankar, Sambasivan [Chicago, IL; Goyal, Amit [Knoxville, TN; Barnett, Scott A [Evanston, IL; Kim, Ilwon [Skokie, IL; Kroeger, Donald M [Knoxville, TN

    2009-03-31

    The present invention relates to epitaxial, electrically conducting and mechanically robust, cubic nitride buffer layers deposited epitaxially on biaxially textured substrates such as metals and alloys. The invention comprises of a biaxially textured substrate with epitaxial layers of nitrides. The invention also discloses a method to form such epitaxial layers using a high rate deposition method as well as without the use of forming gases. The invention further comprises epitaxial layers of oxides on the biaxially textured nitride layer. In some embodiments the article further comprises electromagnetic devices which may have superconducting properties.

  9. The function of buffer layer in resistive switching device.

    Czech Academy of Sciences Publication Activity Database

    Zhang, B.; Prokop, V.; Střižík, L.; Zima, Vítězslav; Kutálek, P.; Vlček, Milan; Wágner, T.

    2017-01-01

    Roč. 14, č. 8 (2017), s. 291-295 ISSN 1584-8663 Institutional support: RVO:61389013 Keywords : resistive switching * chalcogenide glasses * buffer layer Subject RIV: CA - Inorganic Chemistry Impact factor: 0.732, year: 2016 http://www.chalcogen.ro/291_ZhangB.pdf

  10. Substrate-induced magnetism in epitaxial graphene buffer layers.

    Science.gov (United States)

    Ramasubramaniam, A; Medhekar, N V; Shenoy, V B

    2009-07-08

    Magnetism in graphene is of fundamental as well as technological interest, with potential applications in molecular magnets and spintronic devices. While defects and/or adsorbates in freestanding graphene nanoribbons and graphene sheets have been shown to cause itinerant magnetism, controlling the density and distribution of defects and adsorbates is in general difficult. We show from first principles calculations that graphene buffer layers on SiC(0001) can also show intrinsic magnetism. The formation of graphene-substrate chemical bonds disrupts the graphene pi-bonds and causes localization of graphene states near the Fermi level. Exchange interactions between these states lead to itinerant magnetism in the graphene buffer layer. We demonstrate the occurrence of magnetism in graphene buffer layers on both bulk-terminated as well as more realistic adatom-terminated SiC(0001) surfaces. Our calculations show that adatom density has a profound effect on the spin distribution in the graphene buffer layer, thereby providing a means of engineering magnetism in epitaxial graphene.

  11. Very High Isp Thruster with Anode Layer (VHITAL): An Overview

    Science.gov (United States)

    Marrese-Reading, Colleen M.; Frisbee, Robert; Sengupta, Anita; Cappelli, Mark A.; Tverdoklebov, Sergey; Semenkin, Sasha; Boyd, Iain

    2004-01-01

    This article describes the two stage bismuth fueled Hall thruster technology that was developed at TsNIIMASH [1] and the Very High Isp Thruster with Anode Layer (VHITAL) technology assessment program that is funded by NASA Exploration Systems Mission Directorate (ESMD)' Prometheus program. The overall objective of this program is to evaluate the potential for this Russian-developed thruster technology to enable near-term, Nuclear Electric Propulsion (NEf)-enabled ESMD missions to the outer planets. This 2.5 year program will provide the technology basis for the development of even higher power anode layer thrusters for rapid outer planet exploration missions and, ultimately, human exploration of the solar system. The first 6 month phase is currently in progress. If this phase is successful, the second (1 year) and third (1 year) phase of the proposed program will follow.

  12. Characteristics of the low power cylindrical anode layer ion source

    International Nuclear Information System (INIS)

    Zhao Jie; Tang Deli; Cheng Changming; Geng Shaofei

    2009-01-01

    A low power cylindrical anode layer ion source and its working characteristic, and the beam distribution are introduced. This ion source has two working states, emanative state and collimated state, and the normal parameters of this system are: working voltage 200-1200 V, discharge current 0.1-1.4A, air pressure 1.9 x 10 -2 -1.7 x 10 -1 Pa, gas flow 5-20 sccm. (authors)

  13. ZnO thin films fabricated by chemical bath deposition, used as buffer layer in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lare, Y. [Laboratoire sue l' Energie Solaire, Universite de Lome, Lome (Togo); Godoy, A. [Facultad Ciencias de la Salud, Universidad Diego Portales, Ejercito 141, Santiago de Chile (Chile); Cattin, L. [Universite de Nantes, Nantes Atlantique Universites, IMN, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes, F-44000 France (France); Jondo, K. [Laboratoire sue l' Energie Solaire, Universite de Lome, Lome (Togo); Abachi, T. [Ecole Normale Superieure, Kouba, Alger (Algeria); Diaz, F.R. [Laboratorio de Polimeros, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Casilla 306, Correo 22, Santiago (Chile); Morsli, M. [Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes, F-44000 France (France); Napo, K. [Laboratoire sue l' Energie Solaire, Universite de Lome, Lome (Togo); del Valle, M.A. [Laboratorio de Polimeros, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Casilla 306, Correo 22, Santiago (Chile); Bernede, J.C., E-mail: jean-christian.bernede@univ-nantes.fr [Universite de Nantes, Nantes Atlantique Universites, LAMP, EA 3825, Faculte des Sciences et des Techniques, 2 rue de la Houssiniere, BP 92208, Nantes, F-44000 France (France)

    2009-04-15

    ZnO thin films synthetized by chemical bath deposition are used as buffer layer between the anode and the organic electron donor in organic solar cells. Films deposited from zinc nitrate solutions are annealed in room air at 300 deg. C for half an hour. The X-ray diffraction and microanalysis studies show that ZnO polycrystalline thin films are obtained. The solar cells used are based on the couple copper phthalocyanine as electron donor and (N,N-diheptyl-3,4,9,10-perylenetetracarboxylicdiimide-PTCDI-C7) as electron acceptor. It is shown that the presence of the ZnO buffer layer improves the energy conversion efficiency of the cells. Such improvement could be attributed to a better energy level alignment at the anode/electron donor interface. The anode roughness induced by the ZnO buffer layer can also transform the planar interface organic electron donor/electron acceptor into roughen topography. This increases the interface area, where carrier separation takes place, which improves solar cells performances.

  14. Layer-by-layer graphene/TCNQ stacked films as conducting anodes for organic solar cells.

    Science.gov (United States)

    Hsu, Chang-Lung; Lin, Cheng-Te; Huang, Jen-Hsien; Chu, Chih-Wei; Wei, Kung-Hwa; Li, Lain-Jong

    2012-06-26

    Large-area graphene grown by chemical vapor deposition (CVD) is a promising candidate for transparent conducting electrode applications in flexible optoelectronic devices such as light-emitting diodes or organic solar cells. However, the power conversion efficiency (PCE) of the polymer photovoltaic devices using a pristine CVD graphene anode is still not appealing due to its much lower conductivity than that of conventional indium tin oxide. We report a layer-by-layer molecular doping process on graphene for forming sandwiched graphene/tetracyanoquinodimethane (TCNQ)/graphene stacked films for polymer solar cell anodes, where the TCNQ molecules (as p-dopants) were securely embedded between two graphene layers. Poly(3-hexylthiophene)/phenyl-C61-butyric acid methyl ester (P3HT/PCBM) bulk heterojunction polymer solar cells based on these multilayered graphene/TCNQ anodes are fabricated and characterized. The P3HT/PCBM device with an anode structure composed of two TCNQ layers sandwiched by three CVD graphene layers shows optimum PCE (∼2.58%), which makes the proposed anode film quite attractive for next-generation flexible devices demanding high conductivity and transparency.

  15. Anodic characteristics and stress corrosion cracking behavior of nickel rich alloys in bicarbonate and buffer solutions

    International Nuclear Information System (INIS)

    Zadorozne, Natalia S.; Giordano, Mabel C.; Ares, Alicia E.; Carranza, Ricardo M.; Rebak, Raul B.

    2016-01-01

    Highlights: • We investigate which element in alloy C-22 may be responsible for the cracking susceptibility of the high nickel alloy. • Six nickel based alloys with different amount of Cr and Mo were selected for the electrochemical tests and response to SSRT. • Polarization tests showed that an anodic peak appear in the passive region in Cr containing alloys. • Cracking of Ni alloys in carbonate solutions seem to be a consequence of the instability of the passivating chromium oxide. • Alloys containing both Cr and Mo have the highest susceptibility. - Abstract: The aim of this work is to investigate which alloying element in C-22 is responsible for the cracking susceptibility of the alloy in bicarbonate and two buffer solutions (tungstate and borate). Six nickel based alloys, with different amount of chromium (Cr) and molybdenum (Mo) were tested using electrochemical methods and slow strain rate tests (SSRT) at 90 °C. All Cr containing alloys had transgranular cracking at high anodic potential; however, C-22 containing high Cr and high Mo was the most susceptible alloy to cracking. Bicarbonate was the most aggressive of three tested environments of similar pH.

  16. Process and electrolyte for applying barrier layer anodic coatings

    International Nuclear Information System (INIS)

    Dosch, R.G.; Prevender, T.S.

    1975-01-01

    Various metals may be anodized, and preferably barrier anodized, by anodizing the metal in an electrolyte comprising quaternary ammonium compound having a complex metal anion in a solvent containing water and a polar, water soluble organic material. (U.S.)

  17. Organometallic tris(8-hydroxyquinoline)aluminum complexes as buffer layers and dopants in inverted organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tolkki, Antti, E-mail: antti.tolkki@tut.fi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Kaunisto, Kimmo [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Heiskanen, Juha P. [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Department of Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Oulu (Finland); Omar, Walaa A.E. [Department of Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Oulu (Finland); Chemistry Branch, Department of Science and Mathematics, Suez Canal University, Suez 43721 (Egypt); Huttunen, Kirsi; Lehtimaeki, Suvi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland); Hormi, Osmo E.O. [Department of Chemistry, University of Oulu, P.O. Box 3000, FI-90014, Oulu (Finland); Lemmetyinen, Helge [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101, Tampere (Finland)

    2012-04-30

    Tris(8-hydroxyquinoline)aluminum (Alq{sub 3}) is a frequently used material for organic light emitting diodes. The electronic properties and solubility can be tuned by chemical tailoring of the quinoline part, which makes it an interesting candidate for organic solar cells. Steady-state absorption and fluorescence, as well as time-resolved fluorescence properties of the parent Alq{sub 3} and a series of complexes consisting of derivatives, such as 4-substituted pyrazol, methylpyrazol, arylvinyl, and pyridinoanthrene moieties, of the quinoline ligand, were studied in solutions and in thin films. Suitability of the complexes as anodic buffer layers or dopants in inverted organic solar cells based on the well known bulk heterojunction of poly(3-hexylthiophene) (P3HT) and phenyl-C{sub 61}-butyric acid methyl ester (PCBM) was tested. The devices equipped with the derivatives showed higher power conversion efficiency ({eta}) compared to the photocells containing the parent Alq{sub 3}. Open circuit voltage (V{sub oc}) was increased when the derivatives were utilized as the anodic buffer layer. Doping of the P3HT:PCBM with a small amount of Alq{sub 3} or its derivative improved short circuit current density, V{sub oc}, fill factor, and {eta}, while the series resistance decreased. In addition, the devices were stable in air over several weeks without encapsulation. Possible mechanisms leading to the improvements in the photovoltaic performance by using the parent Alq{sub 3} or its derivative as buffer layer or dopant are discussed. - Highlights: Black-Right-Pointing-Pointer Tris(8-hydroxyquinoline)aluminum (Alq{sub 3}) complexes in inverted organic solar cells. Black-Right-Pointing-Pointer The Alq{sub 3} complexes were used as an anodic buffer layer and as a dopant. Black-Right-Pointing-Pointer Efficiency increased and the derivatives revealed varying open circuit voltage. Black-Right-Pointing-Pointer Photovoltaic performance was stable after storage in a dark ambient

  18. Organometallic tris(8-hydroxyquinoline)aluminum complexes as buffer layers and dopants in inverted organic solar cells

    International Nuclear Information System (INIS)

    Tolkki, Antti; Kaunisto, Kimmo; Heiskanen, Juha P.; Omar, Walaa A.E.; Huttunen, Kirsi; Lehtimäki, Suvi; Hormi, Osmo E.O.; Lemmetyinen, Helge

    2012-01-01

    Tris(8-hydroxyquinoline)aluminum (Alq 3 ) is a frequently used material for organic light emitting diodes. The electronic properties and solubility can be tuned by chemical tailoring of the quinoline part, which makes it an interesting candidate for organic solar cells. Steady-state absorption and fluorescence, as well as time-resolved fluorescence properties of the parent Alq 3 and a series of complexes consisting of derivatives, such as 4-substituted pyrazol, methylpyrazol, arylvinyl, and pyridinoanthrene moieties, of the quinoline ligand, were studied in solutions and in thin films. Suitability of the complexes as anodic buffer layers or dopants in inverted organic solar cells based on the well known bulk heterojunction of poly(3-hexylthiophene) (P3HT) and phenyl-C 61 -butyric acid methyl ester (PCBM) was tested. The devices equipped with the derivatives showed higher power conversion efficiency (η) compared to the photocells containing the parent Alq 3 . Open circuit voltage (V oc ) was increased when the derivatives were utilized as the anodic buffer layer. Doping of the P3HT:PCBM with a small amount of Alq 3 or its derivative improved short circuit current density, V oc , fill factor, and η, while the series resistance decreased. In addition, the devices were stable in air over several weeks without encapsulation. Possible mechanisms leading to the improvements in the photovoltaic performance by using the parent Alq 3 or its derivative as buffer layer or dopant are discussed. - Highlights: ► Tris(8-hydroxyquinoline)aluminum (Alq 3 ) complexes in inverted organic solar cells. ► The Alq 3 complexes were used as an anodic buffer layer and as a dopant. ► Efficiency increased and the derivatives revealed varying open circuit voltage. ► Photovoltaic performance was stable after storage in a dark ambient atmosphere.

  19. Simulation study on single event burnout in linear doping buffer layer engineered power VDMOSFET

    International Nuclear Information System (INIS)

    Jia Yunpeng; Su Hongyuan; Hu Dongqing; Wu Yu; Jin Rui

    2016-01-01

    The addition of a buffer layer can improve the device's secondary breakdown voltage, thus, improving the single event burnout (SEB) threshold voltage. In this paper, an N type linear doping buffer layer is proposed. According to quasi-stationary avalanche simulation and heavy ion beam simulation, the results show that an optimized linear doping buffer layer is critical. As SEB is induced by heavy ions impacting, the electric field of an optimized linear doping buffer device is much lower than that with an optimized constant doping buffer layer at a given buffer layer thickness and the same biasing voltages. Secondary breakdown voltage and the parasitic bipolar turn-on current are much higher than those with the optimized constant doping buffer layer. So the linear buffer layer is more advantageous to improving the device's SEB performance. (paper)

  20. Design and numerical simulation of the electromagnetic field of linear anode layer ion source

    International Nuclear Information System (INIS)

    Wang Lisheng; Tang Deli; Cheng Changming

    2006-01-01

    The principle of anode layer ion source for etching, pre-cleaning and ion beam assisted deposition was described. The influence of the magnetic field on the performance of anode layer ion source was analyzed. Design of the magnetic loop for the linear anode layer ion source was given. The electromagnetic field distribution of the ion source was simulated by means of ANSYS code and the simulation results were in agreement with experimental ones. The numerical simulation results of the electromagnetic field are useful for improving the anode layer ion source. (authors)

  1. Buffer layer enhanced stability of sodium-ion storage

    Science.gov (United States)

    Wang, Xusheng; Yang, Zhanhai; Wang, Chao; Chen, Dong; Li, Rui; Zhang, Xinxiang; Chen, Jitao; Xue, Mianqi

    2017-11-01

    Se-Se buffer layers are introduced into tin sequences as SnSe2 single crystal to enhance the cycling stability for long-term sodium-ion storage by blazing a trail of self-defence strategy to structural pulverization especially at high current density. Specifically, under half-cell test, the SnSe2 electrodes could yield a high discharge capacity of 345 mAh g-1 after 300 cycles at 1 A g-1 and a high discharge capacity of 300 mAh g-1 after 2100 cycles at 5 A g-1 with stable coulombic efficiency and no capacity fading. Even with the ultrafast sodium-ion storage at 10 A g-1, the cycling stability still makes a positive response and a high discharge capacity of 221 mAh g-1 is demonstrated after 2700 cycles without capacity fading. The full-cell test for the SnSe2 electrodes also demonstrates the superior cycling stability. The flexible and tough Se-Se buffer layers are favourable to accommodate the sodium-ion intercalation process, and the autogenous Na2Se layers could confine the structural pulverization of further sodiated tin sequences by the slip along the Na2Se-NaxSn interfaces.

  2. In situ TEM observation of buffering the anode volume change by using NiTi alloy during electrochemical lithiation/delithiation.

    Science.gov (United States)

    Zhang, L Q; Zhang, J S; Shao, Y; Jiang, D Q; Yang, F; Guo, Y P; Cui, L S

    2013-08-16

    A novel Ti3Sn/NiTi shape memory alloy anode with a sandwich structure was fabricated by arc melting. In order to characterize in situ the Ti3Sn/NiTi anode microstructure changes and phase transformations during cycling, a nanoscale lithium battery was set up inside a transmission electron microscope, which consists of Li metal as the cathode, the native Li2O layer on the surface of Li metal as the solid electrolyte, and the Ti3Sn/NiTi as the anode. Only the Ti3Sn intermetallic compound experienced the electrochemical reaction, while the NiTi alloy (inactive with Li(+)) was applied for buffering the Ti3Sn volume change during cycling. An obvious reaction front of Ti3Sn migrated from one end to the other during lithiation, which can also return after delithiation. It provides direct evidence that the NiTi alloy can effectively accommodate the anode volume change during electrochemical lithiation and delithiation.

  3. Electrochemical performance of Sn-Sb-Cu film anodes prepared by layer-by-layer electrodeposition

    International Nuclear Information System (INIS)

    Jiang Qianlei; Xue Ruisheng; Jia Mengqiu

    2012-01-01

    A novel layer-by-layer electrodeposition and heat-treatment approach was attempted to obtain Sn-Sb-Cu film anode for lithium ion batteries. The preparation of Sn-Sb-Cu anodes started with galvanostatic electrochemically depositing antimony and tin sequentially on the substrate of copper foil collector. Sn-Sb and Cu-Sb alloys were formed when heated. The SEM analysis showed that the crystalline grains become bigger and the surface of the Sn-Sb-Cu anode becomes more denser after annealing. The energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis showed the antimony, tin and copper were alloyed to form SnSb and Cu 2 Sb after heat treatment. The X-ray photoelectron spectroscopy (XPS) analysis showed the surface of the Sn-Sb-Cu electrode was covered by a thin oxide layer. Electrochemical measurements showed that the annealed Sn-Sb-Cu anode has high reversible capacity and good capacity retention. It exhibited a reversible capacity of about 962 mAh/g in the initial cycle, which still remained 715 mAh/g after 30 cycles.

  4. Solid oxide fuel cell bi-layer anode with gadolinia-doped ceria for utilization of solid carbon fuel

    Science.gov (United States)

    Kellogg, Isaiah D.; Koylu, Umit O.; Dogan, Fatih

    Pyrolytic carbon was used as fuel in a solid oxide fuel cell (SOFC) with a yttria-stabilized zirconia (YSZ) electrolyte and a bi-layer anode composed of nickel oxide gadolinia-doped ceria (NiO-GDC) and NiO-YSZ. The common problems of bulk shrinkage and emergent porosity in the YSZ layer adjacent to the GDC/YSZ interface were avoided by using an interlayer of porous NiO-YSZ as a buffer anode layer between the electrolyte and the NiO-GDC primary anode. Cells were fabricated from commercially available component powders so that unconventional production methods suggested in the literature were avoided, that is, the necessity of glycine-nitrate combustion synthesis, specialty multicomponent oxide powders, sputtering, or chemical vapor deposition. The easily-fabricated cell was successfully utilized with hydrogen and propane fuels as well as carbon deposited on the anode during the cyclic operation with the propane. A cell of similar construction could be used in the exhaust stream of a diesel engine to capture and utilize soot for secondary power generation and decreased particulate pollution without the need for filter regeneration.

  5. Sn buffered by shape memory effect of NiTi alloys as high-performance anodes for lithium ion batteries

    International Nuclear Information System (INIS)

    Hu Renzong; Zhu Min; Wang Hui; Liu Jiangwen; Liuzhang Ouyang; Zou Jin

    2012-01-01

    By applying the shape memory effect of the NiTi alloys to buffer the Sn anodes, we demonstrate a simple approach to overcome a long-standing challenge of Sn anode in the applications of Li-ion batteries – the capacity decay. By supporting the Sn anodes with NiTi shape memory alloys, the large volume change of Sn anodes due to lithiation and delithiation can be effectively accommodated, based on the stress-induced martensitic transformation and superelastic recovery of the NiTi matrix respectively, which leads to a decrease in the internal stress and closing of cracks in Sn anodes. Accordingly, stable cycleability (630 mA h g −1 after 100 cycles at 0.7C) and excellent high-rate capabilities (478 mA h g −1 at 6.7C) were attained with the NiTi/Sn/NiTi film electrode. These shape memory alloys can also combine with other high-capacity metallic anodes, such as Si, Sb, Al, and improve their cycle performance.

  6. Elastic strain relief in nitridated Ga metal buffer layers for epitaxial GaN growth

    International Nuclear Information System (INIS)

    Kim, Yihwan; Shapiro, Noad A.; Feick, Henning; Armitage, Robert; Weber, Eicke R.; Yang, Yi; Cerrina, Franco

    2001-01-01

    Gallium nitride epitaxial layers were grown on sapphire by molecular-beam epitaxy using nitridated gallium metal films as buffer layers. The mechanical properties of the buffer layers were investigated and correlated with their chemical composition as determined by synchrotron radiation photoelectron spectroscopy. Biaxial tension experiments were performed by bending the substrates in a pressure cell designed for simultaneous photoluminescence measurements. The shift of the excitonic luminescence peak was used to determine the stress induced in the main GaN epilayer. The fraction of stress transferred from substrate to main layer was as low as 27% for samples grown on nitridated metal buffer layers, compared to nearly 100% for samples on conventional low-temperature GaN buffer layers. The efficiency of stress relief increased in proportion to the fraction of metallic Ga in the nitridated metal buffer layers. These findings suggest GaN films containing residual metallic Ga may serve as compliant buffer layers for heteroepitaxy

  7. The effect of Cr buffer layer thickness on voltage generation of thin-film thermoelectric modules

    International Nuclear Information System (INIS)

    Mizoshiri, Mizue; Mikami, Masashi; Ozaki, Kimihiro

    2013-01-01

    The effect of Cr buffer layer thickness on the open-circuit voltage generated by thin-film thermoelectric modules of Bi 0.5 Sb 1.5 Te 3 (p-type) and Bi 2 Te 2.7 Se 0.3 (n-type) materials was investigated. A Cr buffer layer, whose thickness generally needs to be optimized to improve adhesion depending on the substrate surface condition, such as roughness, was deposited between thermoelectric thin films and glass substrates. When the Cr buffer layer was 1 nm thick, the Seebeck coefficients and electrical conductivity of 1 µm thermoelectric thin films with the buffer layers were approximately equal to those of the thermoelectric films without the buffer layers. When the thickness of the Cr buffer layer was 1 µm, the same as the thermoelectric films, the Seebeck coefficients of the bilayer films were reduced by an electrical current flowing inside the Cr buffer layer and the generation of Cr 2 Te 3 . The open-circuit voltage of the thin-film thermoelectric modules decreased with an increase in the thickness of the Cr buffer layer, which was primarily induced by the electrical current flow. The reduction caused by the Cr 2 Te 3 generation was less than 10% of the total voltage generation of the modules without the Cr buffer layers. The voltage generation of thin-film thermoelectric modules could be controlled by the Cr buffer layer thickness. (paper)

  8. SnO2 anode surface passivation by atomic layer deposited HfO2 improves li-ion battery performance

    KAUST Repository

    Yesibolati, Nulati

    2014-03-14

    For the first time, it is demonstrated that nanoscale HfO2 surface passivation layers formed by atomic layer deposition (ALD) significantly improve the performance of Li ion batteries with SnO2-based anodes. Specifically, the measured battery capacity at a current density of 150 mAg -1 after 100 cycles is 548 and 853 mAhg-1 for the uncoated and HfO2-coated anodes, respectively. Material analysis reveals that the HfO2 layers are amorphous in nature and conformably coat the SnO2-based anodes. In addition, the analysis reveals that ALD HfO2 not only protects the SnO2-based anodes from irreversible reactions with the electrolyte and buffers its volume change, but also chemically interacts with the SnO2 anodes to increase battery capacity, despite the fact that HfO2 is itself electrochemically inactive. The amorphous nature of HfO2 is an important factor in explaining its behavior, as it still allows sufficient Li diffusion for an efficient anode lithiation/delithiation process to occur, leading to higher battery capacity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Effect of unsintered gadolinium-doped ceria buffer layer on performance of metal-supported solid oxide fuel cells using unsintered barium strontium cobalt ferrite cathode

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu-Mi [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea); Kim-Lohsoontorn, Pattaraporn [Department of Chemical Engineering, Mahidol University, Nakorn Pathom 73170 (Thailand); KI for Eco-Energy, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea); Bae, Joongmyeon [Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea); KI for Eco-Energy, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea)

    2010-10-01

    In this study, a Gd{sub 0.1}Ce{sub 0.9}O{sub 1.95} (GDC) buffer layer and a Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) cathode, fabricated without pre-sintering, are investigated (unsintered GDC and unsintered BSCF). The effect of the unsintered GDC buffer layer, including the thickness of the layer, on the performance of solid oxide fuel cells (SOFCs) using an unsintered BSCF cathode is studied. The maximum power density of the metal-supported SOFC using an unsintered BSCF cathode without a buffer layer is 0.81 W cm{sup -2}, which is measured after 2 h of operation (97% H{sub 2} and 3% H{sub 2}O at the anode and ambient air at the cathode), and it significantly decreases to 0.63 W cm{sup -2} after 50 h. At a relatively low temperature of 800 C, SrZrO{sub 3} and BaZrO{sub 3}, arising from interaction between BSCF and yttria-stabilized zirconia (YSZ), are detected after 50 h. Introducing a GDC interlayer between the cathode and electrolyte significantly increases the durability of the cell performance, supporting over 1000 h of cell usage with an unsintered GDC buffer layer. Comparable performance is obtained from the anode-supported cell when using an unsintered BSCF cathode with an unsintered GDC buffer layer (0.75 W cm{sup -2}) and sintered GDC buffer layer (0.82 W cm{sup -2}). When a sintered BSCF cathode is used, however, the performance increases to 1.23 W cm{sup -2}. The adhesion between the BSCF cathode and the cell can be enhanced by an unsintered GDC buffer layer, but an increase in the layer thickness (1-6 {mu}m) increases the area specific resistance (ASR) of the cell, and the overly thick buffer layer causes delamination of the BSCF cathode. Finally, the maximum power densities of the metal-supported SOFC using an unsintered BSCF cathode and unsintered GDC buffer layer are 0.78, 0.64, 0.45 and 0.31 W cm{sup -2} at 850, 800, 750 and 700 C, respectively. (author)

  10. Effect of unsintered gadolinium-doped ceria buffer layer on performance of metal-supported solid oxide fuel cells using unsintered barium strontium cobalt ferrite cathode

    Science.gov (United States)

    Kim, Yu-Mi; Kim-Lohsoontorn, Pattaraporn; Bae, Joongmyeon

    In this study, a Gd 0.1Ce 0.9O 1.95 (GDC) buffer layer and a Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ (BSCF) cathode, fabricated without pre-sintering, are investigated (unsintered GDC and unsintered BSCF). The effect of the unsintered GDC buffer layer, including the thickness of the layer, on the performance of solid oxide fuel cells (SOFCs) using an unsintered BSCF cathode is studied. The maximum power density of the metal-supported SOFC using an unsintered BSCF cathode without a buffer layer is 0.81 W cm -2, which is measured after 2 h of operation (97% H 2 and 3% H 2O at the anode and ambient air at the cathode), and it significantly decreases to 0.63 W cm -2 after 50 h. At a relatively low temperature of 800 °C, SrZrO 3 and BaZrO 3, arising from interaction between BSCF and yttria-stabilized zirconia (YSZ), are detected after 50 h. Introducing a GDC interlayer between the cathode and electrolyte significantly increases the durability of the cell performance, supporting over 1000 h of cell usage with an unsintered GDC buffer layer. Comparable performance is obtained from the anode-supported cell when using an unsintered BSCF cathode with an unsintered GDC buffer layer (0.75 W cm -2) and sintered GDC buffer layer (0.82 W cm -2). When a sintered BSCF cathode is used, however, the performance increases to 1.23 W cm -2. The adhesion between the BSCF cathode and the cell can be enhanced by an unsintered GDC buffer layer, but an increase in the layer thickness (1-6 μm) increases the area specific resistance (ASR) of the cell, and the overly thick buffer layer causes delamination of the BSCF cathode. Finally, the maximum power densities of the metal-supported SOFC using an unsintered BSCF cathode and unsintered GDC buffer layer are 0.78, 0.64, 0.45 and 0.31 W cm -2 at 850, 800, 750 and 700 °C, respectively.

  11. Effect of a cathode buffer layer on the stability of organic solar cells

    International Nuclear Information System (INIS)

    Wang, Danbei; Zeng, Wenjin; Chen, Shilin; Su, Xiaodan; Wang, Jin; Zhang, Hongmei

    2015-01-01

    We present the effect of a cathode buffer layer on the performance and stability of organic photovoltaics (OPVs) based on a blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Six kinds of cathode buffer layers, i.e. lithium fluoride, sodium chloride, NaCl/Mg, tris-(8-hydroxy-quinoline) aluminum, bathocuproine and 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene, were inserted between the photoactive layer and an Al cathode, which played a dominant role in the device’s performance. Devices with the cathode buffer layers above exhibited improved performance. The degradation of these devices with encapsulation was further investigated in an inert atmosphere. The results indicated that devices with inorganic cathode buffer layers exhibited better stability than those with organic cathode buffer layers. (paper)

  12. Numerical simulation of solar cells besed CZTS buffer layer (ZnO 1 ...

    African Journals Online (AJOL)

    Cds buffer layer has many advantages such as large bandgap, and the carrier density. Otherwise, the presence of cadmium is an inconvenient. Research work, are shifted on the possibility of replacing CdS by a buffer layer devoid of cadmium. This manuscript presents the numerical study, using SCAPS-1D program, the ...

  13. Buffer layer investigations on MFIS capacitors consisting of ferroelectric poly[vinylidene fluoride trifluoroethylene

    International Nuclear Information System (INIS)

    Henkel, K; Seime, B; Paloumpa, I; Mueller, K; Schmeisser, D

    2010-01-01

    In this paper we present capacitance-voltage (CV) measurements on metal-ferroelectric-insulator-semiconductor (MFIS) capacitors with poly[vinylidene fluoride trifluoroethylene] (P[VDF/TrFE] as ferroelectric layer and SiO 2 , Al 2 O 3 and HfO 2 as buffering insulator layer. In order to discuss our data in a quantitative manner we perform fits to the data based on a model proposed by Miller and McWorther. The improvement of the polarization values and subsequently its effect on the hysteresis of the CV curve by the successive shrinking of the buffer layer thickness and the following choice of a high-k buffer material is demonstrated. Our data underline that a saturated polarization of P[VDF/TrFE] cannot be controlled with a SiO 2 buffer layer and the insertion of a high-k buffer layer is essential for further improvements of the characteristics of MFIS stacks.

  14. Buffer layer annealing effects on the magnetization reversal process in Pd/Co/Pd systems

    Energy Technology Data Exchange (ETDEWEB)

    Fassatoui, A., E-mail: Fassatouiaymen@Hotmail.com [LMOP: LR99ES17, Faculté des Sciences de Tunis, Université de Tunis El Manar, Tunis, 2092 (Tunisia); Belhi, R. [LMOP: LR99ES17, Faculté des Sciences de Tunis, Université de Tunis El Manar, Tunis, 2092 (Tunisia); Vogel, J. [Institut Néel (CNRS and Université Grenoble Alpes), 25 rue des Martyrs, B. P. 166, Grenoble cedex 9, 38042 (France); Abdelmoula, K. [LMOP: LR99ES17, Faculté des Sciences de Tunis, Université de Tunis El Manar, Tunis, 2092 (Tunisia)

    2016-12-15

    We have investigated the effect of annealing the buffer layer on the magnetization reversal behavior in Pd/Co/Pd thin films using magneto-optical Kerr microscopy. It was found that annealing the buffer layer at 150 °C for 1 h decreases the coercivity and increases the saturation magnetization and the effective magnetic anisotropy constant. This study also shows that the annealing induces a change of the magnetization reversal from a mixed nucleation and domain wall propagation process to one dominated by domain wall propagation. This result demonstrates that the main effect of annealing the buffer layer is to decrease the domain wall pinning in the Co layer, favoring the domain wall propagation mode. - Highlights: • The buffer layer surface morphology changes upon annealing of the buffer layer. • The coercivity decreases while the saturation magnetization and the effective anisotropy increase with the annealing of the buffer layer. • The reversal process changes from a mixed nucleation and domain wall propagation process to one dominated by domain wall propagation when annealing the buffer layer.

  15. Anode-originated SEI migration contributes to formation of cathode-electrolyte interphase layer

    Science.gov (United States)

    Fang, Shuyu; Jackson, David; Dreibelbis, Mark L.; Kuech, Thomas F.; Hamers, Robert J.

    2018-01-01

    Cathode-electrolyte interphase (CEI) formation is a key process that impacts the performance of lithium-ion batteries. In this work, we characterized the composition and stoichiometry of CEI layer on LiNixMnyCo1-x-yO2 (NMC) cathodes via a novel combination of quantitative correlation analysis of X-ray photoelectron spectra and binder-free cathode formulation. By comparing the CEI formation in NMC-based cells with lithium, graphite and lithium titanate anodes, we demonstrate a CEI formation pathway via migration of surface species that originally formed on the anode side. A case study of cathodes coated by atomic layer deposition with a thin layer of Al2O3 demonstrates that anode-to-cathode migration can be mitigated by ALD cathode coatings. This work highlights the importance of anode-mediated processes in order to correctly interpret surface phenomena on the cathode side and to guide further development of surface protection strategies.

  16. Crystallinity Improvement of Zn O Thin Film on Different Buffer Layers Grown by MBE

    International Nuclear Information System (INIS)

    Shao-Ying, T.; Che-Hao, L.; Wen-Ming, Ch.; Yang, C.C.; Po-Ju, Ch.; Hsiang-Chen, W.; Ya-Ping, H.

    2012-01-01

    The material and optical properties of Zn O thin film samples grown on different buffer layers on sapphire substrates through a two-step temperature variation growth by molecular beam epitaxy were investigated. The thin buffer layer between the Zn O layer and the sapphire substrate decreased the lattice mismatch to achieve higher quality Zn O thin film growth. A Ga N buffer layer slightly increased the quality of the Zn O thin film, but the threading dislocations still stretched along the c-axis of the Ga N layer. The use of Mg O as the buffer layer decreased the surface roughness of the Zn O thin film by 58.8% due to the suppression of surface cracks through strain transfer of the sample. From deep level emission and rocking curve measurements it was found that the threading dislocations play a more important role than oxygen vacancies for high-quality Zn O thin film growth.

  17. Band Gap Opening Induced by the Structural Periodicity in Epitaxial Graphene Buffer Layer.

    Science.gov (United States)

    N Nair, Maya; Palacio, Irene; Celis, Arlensiú; Zobelli, Alberto; Gloter, Alexandre; Kubsky, Stefan; Turmaud, Jean-Philippe; Conrad, Matthew; Berger, Claire; de Heer, Walter; Conrad, Edward H; Taleb-Ibrahimi, Amina; Tejeda, Antonio

    2017-04-12

    The epitaxial graphene buffer layer on the Si face of hexagonal SiC shows a promising band gap, of which the precise origin remains to be understood. In this work, we correlate the electronic to the atomic structure of the buffer layer by combining angle resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), and high-resolution scanning transmission electron microscopy (HR-STEM). We show that the band structure in the buffer has an electronic periodicity related to the structural periodicity observed in STM images and published X-ray diffraction. Our HR-STEM measurements show the bonding of the buffer layer to the SiC at specific locations separated by 1.5 nm. This is consistent with the quasi 6 × 6 periodic corrugation observed in the STM images. The distance between buffer C and SiC is 1.9 Å in the bonded regions and up to 2.8 Å in the decoupled regions, corresponding to a 0.9 Å corrugation of the buffer layer. The decoupled regions are sp 2 hybridized. Density functional tight binding (DFTB) calculations demonstrate the presence of a gap at the Dirac point everywhere in the buffer layer, even in the decoupled regions where the buffer layer has an atomic structure close to that of graphene. The surface periodicity also promotes band in the superperiodic Brillouin zone edges as seen by photoemission and confirmed by our calculations.

  18. Enhancement of hole-injection and power efficiency of organic light emitting devices using an ultra-thin ZnO buffer layer

    International Nuclear Information System (INIS)

    Huang, H.-H.; Chu, S.-Y.; Kao, P.-C.; Chen, Y.-C.; Yang, M.-R.; Tseng, Z.-L.

    2009-01-01

    The advantages of using an anode buffer layer of ZnO on the electro-optical properties of organic light emitting devices (OLEDs) are reported. ZnO powders were thermal-evaporated and then treated with ultra-violet (UV) ozone exposure to make the ZnO layers. The turn-on voltage of OLEDs decreased from 4 V (4.2 cd/m 2 ) to 3 V (3.4 cd/m 2 ) and the power efficiency increased from 2.7 lm/W to 4.7 lm/W when a 1-nm-thick ZnO layer was inserted between indium tin oxide (ITO) anodes and α-naphthylphenylbiphenyl diamine (NPB) hole-transporting layers. X-ray and ultra-violet photoelectron spectroscopy (XPS and UPS) results revealed the formation of the ZnO layer and showed that the work function increased by 0.59 eV when the ZnO/ITO layer was treated by UV-ozone for 20 min. The surface of the ZnO/ITO film became smoother than that of bare ITO film after the UV-ozone treatment. Thus, the hole-injection energy barrier was lowered by inserting an ZnO buffer layer, resulting in a decrease of the turn-on voltage and an increase of the power efficiency of OLEDs.

  19. Thermal resistance of buffer layer in a ceramic wall of MHD generation channel

    International Nuclear Information System (INIS)

    Nomura, Osami; Ebata, Yoshihiro; Hijikata, Kenichi.

    1982-01-01

    A wal l model is composed for obtaining the thermal resistance of the buffer layer. A buffer layer of the model is consisted to an adhesive layer and a buffer body. The adhesive layer is made of a copper plate, which is 0.3 mm thick, and adhered to the element by Refractory Method. The adhesive layer is consisted to three layers, i.e., Cu, Cu 2 O and CuO. These three layers seems to give rise to the thermal resistance. The buffer body is made of nickel wires of which radious is 0.4 mm and purity is 99.7%. All of the nickel wires are assembled in one direction which is parallel to a center line of the element, and bundled all together. Occupation ratio of nickel is about 78% in a sectional area of the buffer body. One end of the buffer body is soldered to adhesive layer by silver solder and opposite and is soldered to holder by lead solder. An element of the model is made of magnesia ceramics of which purity is about 99.9% and porosity is about 3%. A holder of the model is made of copper block. Results are as follows: (1) Thermal resistance of the buffer layer is from 1.9 to 2.5K/(W/cm 2 ). (2) Thermal resistance of the adhesive layer is from 0.43 to 0.87K/(W/cm 2 ). (3) Thermal resistance of the buffer body is calculated to about 0.7K/(W/cm 2 ) under the estimation at which the heat flows in the nickel wires only. (4) From above results, thermal resistance of silver soldering layer seems to be same as that of the adhesive layers. The buffer layer needs more value of the thermal resistance in order to apply to the MHD generation channel. Value of the thermal resistance is easily satisfied by changing of material of the buffer body, increase of thickness of the buffer layer and etc. Then this wall appears to be useful to an MHD generation channel wall. (author)

  20. AlGaSb Buffer Layers for Sb-Based Transistors

    Science.gov (United States)

    2010-01-01

    1.5 lm to 3.0 lm buffer layers of AlSb and AlGaSb accommo- dating the lattice mismatch. We demonstrate that high electron mobility in the InAs (>20,000...buffer layers to accommodate the 4% to 15% lattice mismatch. AlSb or alloys of AlGaSb have usually been used as buffer layers. Nguyen et al. achieved...because it is much less reactive than pure AlSb .18 The substrate temperature was then low- ered to 500C for growth of an additional 100 nm of Al0.8Ga0.2Sb

  1. The simulation of the temperature effects on the microhardness of anodic alumina oxide layers

    Directory of Open Access Journals (Sweden)

    M. Gombár

    2014-01-01

    Full Text Available In order to improve the mechanical properties of the layer deposited by anodic oxidation of aluminum on the material EN AW-1050 H24, in the contribution was investigated the microhardness of the deposited layer as a function of the physic-chemical factors affecting in the process of anodic oxidation at the constant anodic current density J = 3 A.dm-2 in electrolyte formed by sulfuric acid and oxalic acid, with the emphasis on the influence of electrolyte temperature in the range – 1,78 °C to 45,78 °C. The model of the studied dependence was compiled based on mathematical and statistical analysis of matrix from experimental obtained data from composite rotation plan of experiment with five independent variable factors (amount of sulfuric acid in the electrolyte, the amount of oxalic acid in the electrolyte, electrolyte, anodizing time and applied voltage.

  2. Tunneling Injection and Exciton Diffusion of White Organic Light-Emitting Diodes with Composed Buffer Layers

    Science.gov (United States)

    Yang, Su-Hua; Wu, Jian-Ping; Huang, Tao-Liang; Chung, Bin-Fong

    2018-02-01

    Four configurations of buffer layers were inserted into the structure of a white organic light emitting diode, and their impacts on the hole tunneling-injection and exciton diffusion processes were investigated. The insertion of a single buffer layer of 4,4'-bis(carbazol-9-yl)biphenyl (CBP) resulted in a balanced carrier concentration and excellent color stability with insignificant chromaticity coordinate variations of Δ x diffusion of excitons were confirmed by the preparation of a dual buffer layer of CBP:tris-(phenylpyridine)-iridine (Ir(ppy)3)/BCP. A maximum current efficiency of 12.61 cd/A with a luminance of 13,850 cd/m2 was obtained at 8 V when a device with a dual-buffer layer of CBP:6 wt.% Ir(ppy)3/BCP was prepared.

  3. Development of Buffer Layer Technologies for LWIR and VLWIR HgCdTe Integration on Si

    National Research Council Canada - National Science Library

    Golding, Terry D

    2005-01-01

    This program proposed to develop manufacturable, cost-effective buffer layer technologies that would allow either hybrid or monolithic integration of LWIR and VLWIR HgCdTe infrared focal plane arrays...

  4. Article with buffer layer and method of making the same

    Science.gov (United States)

    McCamy, James W.; Ma, Zhixun; Kabagambe, Benjamin; Koram, Kwaku K.; Hung, Cheng-Hung; Nelis, Gary J.

    2017-11-14

    A method of forming a coating layer on a glass substrate in a glass manufacturing process includes: providing a first coating precursor material for a selected coating layer composition to at least one multislot coater to form a first coating region of the selected coating layer; and providing a second coating precursor material for the selected coating layer composition to the multislot coater to form a second coating region of the selected coating layer over the first region. The first coating precursor material is different than the second precursor coating material.

  5. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    Science.gov (United States)

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  6. Preparation and Evaluation of Multi-Layer Anodes of Solid Oxide Fuel Cell

    Science.gov (United States)

    Santiago, Diana; Farmer, Serene C.; Setlock, John A.

    2012-01-01

    The development of an energy device with abundant energy generation, ultra-high specific power density, high stability and long life is critical for enabling longer missions and for reducing mission costs. Of all different types of fuel cells, the solid oxide fuel cells (SOFC) is a promising high temperature device that can generate electricity as a byproduct of a chemical reaction in a clean way and produce high quality heat that can be used for other purposes. For aerospace applications, a power-to-weight of (is) greater than 1.0 kW/kg is required. NASA has a patented fuel cell technology under development, capable of achieving the 1.0 kW/kg figure of merit. The first step toward achieving these goals is increasing anode durability. The catalyst plays an important role in the fuel cells for power generation, stability, efficiency and long life. Not only the anode composition, but its preparation and reduction are key to achieving better cell performance. In this research, multi-layer anodes were prepared varying the chemistry of each layer to optimize the performance of the cells. Microstructure analyses were done to the new anodes before and after fuel cell operation. The cells' durability and performance were evaluated in 200 hrs life tests in hydrogen at 850 C. The chemistry of the standard nickel anode was modified successfully reducing the anode degradation from 40% to 8.4% in 1000 hrs and retaining its microstructure.

  7. Efficient and stable polymer solar cells prepared using plasmonic graphene oxides as anode buffers

    Science.gov (United States)

    Chen, Chung-Lei; Chuang, Ming-Kai; Chen, Chyong-Hua; Chu, Chih-Wei; Keshtov, Muchamed L.; Chen, Fang-Chung

    2015-08-01

    Gold nanoparticle-decorated graphene oxides (AuNP-GOs) have been incorporated into inverted organic photovoltaic devices (OPVs) as anode interlayers. The OPVs fabricated with AuNP-GOs exhibited significant improvement in both the short-circuit current and fill factor compared to a reference device fabricated with neat GOs. We attribute the improvement in the efficiency of the device to the plasmonic effects of the AuNP-GO nanocomposites, which induced local enhancement of the electromagnetic field. More importantly, the inverted OPVs also exhibited better reliability after the use of AuNP-GO nanocomposites.

  8. Comparative analysis of strain fields in layers of step-graded metamorphic buffers of various designs

    Science.gov (United States)

    Aleshin, A. N.; Bugaev, A. S.; Ruban, O. A.; Tabachkova, N. Yu.; Shchetinin, I. V.

    2017-10-01

    Spatial distribution of residual elastic strain in the layers of two step-graded metamophic buffers of various designs, grown by molecular beam epitaxy from ternary InxAl1-xAs solutions on GaAs(001) substrates, is obtained using reciprocal space mapping by three-axis X-ray diffractometry and the linear theory of elasticity. The difference in the design of the buffers enabled the formation of a dislocation-free layer with different thickness in each of the heterostructures, which was the main basis of this study. It is shown that, in spite of the different design of graded metamorphic buffers, the nature of strain fields in them is the same, and the residual elastic strains in the final elements of both buffers adjusted for the effect of work hardening subject to the same phenomenological law, which describes the strain relief process in single-layer heterostructures.

  9. Photovoltaic devices comprising zinc stannate buffer layer and method for making

    Science.gov (United States)

    Wu, Xuanzhi; Sheldon, Peter; Coutts, Timothy J.

    2001-01-01

    A photovoltaic device has a buffer layer zinc stannate Zn.sub.2 SnO.sub.4 disposed between the semiconductor junction structure and the transparent conducting oxide (TCO) layer to prevent formation of localized junctions with the TCO through a thin window semiconductor layer, to prevent shunting through etched grain boundaries of semiconductors, and to relieve stresses and improve adhesion between these layers.

  10. Perpendicular magnetization of CoFeB on top of an amorphous buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongseok; Jung, K.Y. [Department of Display and Semiconductor Physics, Korea University, Sejong 339-700 (Korea, Republic of); Joo, Sungjung [Department of Display and Semiconductor Physics, Korea University, Sejong 339-700 (Korea, Republic of); Center for Electricity and Magnetism, Korea Research Institute of Standard and Science, Daejeon 305-340 (Korea, Republic of); Jang, Youngjae; Hong, Jinki [Department of Display and Semiconductor Physics, Korea University, Sejong 339-700 (Korea, Republic of); Lee, B.C.; You, C.Y.; Cho, J.H. [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of); Kim, M.Y. [Department of Nano Physics, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of); Rhie, K., E-mail: krhie@korea.ac.kr [Department of Display and Semiconductor Physics, Korea University, Sejong 339-700 (Korea, Republic of)

    2015-01-15

    Perpendicular magnetic anisotropy was observed in sputtered FeZr/CoFeB/MgO multilayers. A thin paramagnetic amorphous FeZr layer was used as a buffer layer and perpendicular anisotropy was obtained by annealing the samples without an external magnetic field. The critical CoFeB thickness for perpendicular anisotropy was 1.8 nm; the anisotropy changes from out-of-plane to in-plane as the CoFeB thickness increases beyond this point. Perpendicular anisotropy was also enhanced when a Ta layer was capped on top of the MgO layer. The amorphous buffer provided better perpendicular anisotropy than previously reported Ta buffer, and it may be applied to perpendicular magnetization MRAM devices where good uniformity of tunnel junctions is required. - Highlights: • Perpendicular magnetic anisotropy (PMA) of buffer/CoFeB/MgO was investigated. • The PMA was enhanced by using an amorphous buffer. • The PMA of the CoFeB layer was maintained up to 1.8 nm. • Ta capping layer further improved the PMA by 40%.

  11. Dependence of magnetic properties on different buffer layers of Mn3.5Ga thin films

    Science.gov (United States)

    Takahashi, Y.; Sato, K.; Shima, T.; Doi, M.

    2018-05-01

    D022-Mn3.5Ga thin films were prepared on MgO (100) single crystalline substrates with different buffer layer (Cr, Fe, Cr/Pt and Cr/Au) using an ultra-high-vacuum electron beam vapor deposition system. From XRD patterns, a fundamental (004) peak has clearly observed for all samples. The relatively low saturation magnetization (Ms) of 178 emu/cm3, high magnetic anisotropy (Ku) of 9.1 Merg/cm3 and low surface roughness (Ra) of 0.30 nm were obtained by D022-Mn3.5Ga film (20 nm) on Cr/Pt buffer layer at Ts = 300 °C, Ta = 400 °C (3h). These findings suggest that MnGa film on Cr/Pt buffer layer is a promising PMA layer for future spin electronics devices.

  12. Auto-compensation of ion beam in an accelerator with anode layer

    International Nuclear Information System (INIS)

    Bizyukov, A.A.; Kashaba, A.E.; Sereda, K.N.; Tselujko, A.F.; Yunakov, N.N.

    1997-01-01

    Experiments of studies on the ion beam auto-compensation are described. It is shown that in the accelerators with anode layer in the case of insulated collector there appears the auto-compensation due to excitation of additional non-independent gaseous discharge

  13. Effect of dual buffer layer structure on the epitaxial growth of AlN on sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Wu, L.L.; Le, L.C.; Li, L.; Chen, P.; Liu, Z.S. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhu, J.J.; Wang, H.; Zhang, S.M. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Yang, H. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer A dual AlN buffer layer structure is proposed to grow AlN films. Black-Right-Pointing-Pointer AlN films could be improved obviously by using the dual AlN buffer layer. Black-Right-Pointing-Pointer The physical mechanism are discussed. - Abstract: A dual AlN buffer layer structure, including an isolated layer and a nucleation layer, is proposed to improve the growth of AlN films on sapphire substrate by metal organic chemical vapor deposition. This method is aimed to weaken the negative nitridation effect and improve lateral growth condition in the initial growth stage. It is found that suitably increasing the thickness of the nucleation layer is in favor of a better structural quality of the AlN film. An examination of surface morphology by atomic force microscopy suggests that the thicker the dual AlN buffer layer, the rougher the surface, and a higher quality of AlN epilayer is resulted.

  14. Anomalous acceleration of ions in a plasma accelerator with an anodic layer

    Science.gov (United States)

    V, M. BARDAKOV; S, D. IVANOV; A, V. KAZANTSEV; N, A. STROKIN; A, N. STUPIN; Binhao, JIANG; Zhenyu, WANG

    2018-03-01

    In a plasma accelerator with an anodic layer (PAAL), we discovered experimentally the effect of ‘super-acceleration’ of the bulk of the ions to energies W exceeding the energy equivalent to the discharge voltage V d. The E × B discharge was ignited in an environment of atomic argon and helium and molecular nitrogen. Singly charged argon ions were accelerated most effectively in the case of the largest discharge currents and pressure P of the working gas. Helium ions with W > eV d (e being the electron charge) were only recorded at maximum pressures. Molecular nitrogen was not accelerated to energies W > eV d. Anomalous acceleration is realized in the range of radial magnetic fields on the anode 2.8 × 10 -2 ≤ B rA ≤ 4 × 10 -2 T. It was also found analytically that the cathode of the accelerator can receive anomalously accelerated ions. In this case, the value of the potential in the anodic layer becomes higher than the anode potential, and the anode current exceeds some critical value. Numerical modeling in terms of the developed theory showed qualitative agreement between modeling data and measurements.

  15. In situ formation of graphene layers on graphite surfaces for efficient anodes of microbial fuel cells.

    Science.gov (United States)

    Tang, Jiahuan; Chen, Shanshan; Yuan, Yong; Cai, Xixi; Zhou, Shungui

    2015-09-15

    Graphene can be used to improve the performance of the anode in a microbial fuel cell (MFC) due to its good biocompatibility, high electrical conductivity and large surface area. However, the chemical production and modification of the graphene on the anode are environmentally hazardous because of the use of various harmful chemicals. This study reports a novel method based on the electrochemical exfoliation of a graphite plate (GP) for the in situ formation of graphene layers on the surface of a graphite electrode. When the resultant graphene-layer-based graphite plate electrode (GL/GP) was used as an anode in an MFC, a maximum power density of 0.67 ± 0.034 W/m(2) was achieved. This value corresponds to 1.72-, 1.56- and 1.26-times the maximum power densities of the original GP, exfoliated-graphene-modified GP (EG/GP) and chemically-reduced-graphene-modified GP (rGO/GP) anodes, respectively. Electrochemical measurements revealed that the high performance of the GL/GP anode was attributable to its macroporous structure, improved electron transfer and high electrochemical capacitance. The results demonstrated that the proposed method is a facile and environmentally friendly synthesis technique for the fabrication of high-performance graphene-based electrodes for use in microbial energy harvesting. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Hafnium nitride buffer layers for growth of GaN on silicon

    Science.gov (United States)

    Armitage, Robert D.; Weber, Eicke R.

    2005-08-16

    Gallium nitride is grown by plasma-assisted molecular-beam epitaxy on (111) and (001) silicon substrates using hafnium nitride buffer layers. Wurtzite GaN epitaxial layers are obtained on both the (111) and (001) HfN/Si surfaces, with crack-free thickness up to 1.2 {character pullout}m. However, growth on the (001) surface results in nearly stress-free films, suggesting that much thicker crack-free layers could be obtained.

  17. Defect Reduction in Epitaxial Growth Using Superlattice Buffer Layers

    Science.gov (United States)

    1988-07-01

    R. Shealy, Appl. Phys. Lett. 48, 925 (1986). "M. Razeghi and J. I’. Duchenin, J. Cryst (irokl 70. 145 ’H. Temkin , M. B. Panish, P.M. Petroff, K. A...exposure time, it is possible 500-A GaAso9 P00 y cap. The GaAs 97 P 0 3 layers were that the adsorption process is controlled by surface kinetics grown

  18. Buffer layer between a planar optical concentrator and a solar cell

    Directory of Open Access Journals (Sweden)

    Manuel E. Solano

    2015-09-01

    Full Text Available The effect of inserting a buffer layer between a periodically multilayered isotropic dielectric (PMLID material acting as a planar optical concentrator and a photovoltaic solar cell was theoretically investigated. The substitution of the photovoltaic material by a cheaper dielectric material in a large area of the structure could reduce the fabrication costs without significantly reducing the efficiency of the solar cell. Both crystalline silicon (c-Si and gallium arsenide (GaAs were considered as the photovoltaic material. We found that the buffer layer can act as an antireflection coating at the interface of the PMLID and the photovoltaic materials, and the structure increases the spectrally averaged electron-hole pair density by 36% for c-Si and 38% for GaAs compared to the structure without buffer layer. Numerical evidence indicates that the optimal structure is robust with respect to small changes in the grating profile.

  19. Buffer layer between a planar optical concentrator and a solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Solano, Manuel E. [Departamento de Ingeniería Matemática and CI" 2 MA, Universidad de Concepción, Concepción, Casilla 160-C (Chile); Barber, Greg D. [Penn State Institute of Energy and the Environment, Pennsylvania State University, University Park, PA 16802 (United States); Department of Chemistry, Pennsylvania State University, University Park, PA 16802 (United States); Lakhtakia, Akhlesh [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802 (United States); Faryad, Muhammad [Department of Physics, Lahore University of Management Sciences, Lahore 54792 (Pakistan); Monk, Peter B. [Department of Mathematical Sciences, University of Delaware, Newark, DE 19716 (United States); Mallouk, Thomas E. [Department of Chemistry, Pennsylvania State University, University Park, PA 16802 (United States)

    2015-09-15

    The effect of inserting a buffer layer between a periodically multilayered isotropic dielectric (PMLID) material acting as a planar optical concentrator and a photovoltaic solar cell was theoretically investigated. The substitution of the photovoltaic material by a cheaper dielectric material in a large area of the structure could reduce the fabrication costs without significantly reducing the efficiency of the solar cell. Both crystalline silicon (c-Si) and gallium arsenide (GaAs) were considered as the photovoltaic material. We found that the buffer layer can act as an antireflection coating at the interface of the PMLID and the photovoltaic materials, and the structure increases the spectrally averaged electron-hole pair density by 36% for c-Si and 38% for GaAs compared to the structure without buffer layer. Numerical evidence indicates that the optimal structure is robust with respect to small changes in the grating profile.

  20. The function of microporous layers and the interaction between the anode and cathode in DMFCs

    DEFF Research Database (Denmark)

    Zhang, H. F.; Wang, SY; Pei, PC

    2008-01-01

    A combined effect of microporous layers (MPLs) on direct methanol fuel cells (DMFCs) is investigated. From the distribution of the outstanding carbon loading combinations of the cathode MPL and anode MPL as well as the evolutions of polarization curves, a combined effect in which the contributions...... of the two MPLs interdepend is observed. A further discussion indicates that either MPL in DMFCs is of double roles: a side role of obstructing mass transfers and a main role of adjusting an interaction between the anode and cathode. It is inferred that it is the combination of the two roles that produces...... the combined effect....

  1. Increased Power in Sediment Microbial Fuel Cell: Facilitated Mass Transfer via a Water-Layer Anode Embedded in Sediment

    OpenAIRE

    Lee, Yoo Seok; An, Junyeong; Kim, Bongkyu; Park, HyunJun; Kim, Jisu; Chang, In Seop

    2015-01-01

    We report a methodology for enhancing the mass transfer at the anode electrode of sediment microbial fuel cells (SMFCs), by employing a fabric baffle to create a separate water-layer for installing the anode electrode in sediment. The maximum power in an SMFC with the anode installed in the separate water-layer (SMFC-wFB) was improved by factor of 6.6 compared to an SMFC having the anode embedded in the sediment (SMFC-woFB). The maximum current density in the SMFC-wFB was also 3.9 times highe...

  2. Crystallinity Improvement of ZnO Thin Film on Different Buffer Layers Grown by MBE

    Directory of Open Access Journals (Sweden)

    Shao-Ying Ting

    2012-01-01

    Full Text Available The material and optical properties of ZnO thin film samples grown on different buffer layers on sapphire substrates through a two-step temperature variation growth by molecular beam epitaxy were investigated. The thin buffer layer between the ZnO layer and the sapphire substrate decreased the lattice mismatch to achieve higher quality ZnO thin film growth. A GaN buffer layer slightly increased the quality of the ZnO thin film, but the threading dislocations still stretched along the c-axis of the GaN layer. The use of MgO as the buffer layer decreased the surface roughness of the ZnO thin film by 58.8% due to the suppression of surface cracks through strain transfer of the sample. From deep level emission and rocking curve measurements it was found that the threading dislocations play a more important role than oxygen vacancies for high-quality ZnO thin film growth.

  3. OPTIMISATION OF BUFFER SIZE FOR ENHANCING QOS OF VIDEO TRAFFIC USING CROSS LAYERED HYBRID TRANSPORT LAYER PROTOCOL APPROACH

    Directory of Open Access Journals (Sweden)

    S. Matilda

    2011-03-01

    Full Text Available Video streaming is gaining importance, with the wide popularity of multimedia rich applications in the Internet. Video streams are delay sensitive and require seamless flow for continuous visualization. Properly designed buffers offer a solution to queuing delay. The diagonally opposite QoS metrics associated with video traffic poses an optimization problem, in the design of buffers. This paper is a continuation of our previous work [1] and deals with the design of buffers. It aims at finding the optimum buffer size for enhancing QoS offered to video traffic. Network-centric QoS provisioning approach, along with hybrid transport layer protocol approach is adopted, to arrive at an optimum size which is independent of RTT. In this combinational approach, buffers of routers and end devices are designed to satisfy the various QoS parameters at the transport layer. OPNET Modeler is used to simulate environments for testing the design. Based on the results of simulation it is evident that the hybrid transport layer protocol approach is best suited for transmitting video traffic as it supports the economical design.

  4. Breathing oscillations in enlarged cylindrical-anode-layer Hall plasma accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Geng, S. F.; Wang, C. X. [Southwestern Institute of Physics, Chengdu 610041 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Tang, D. L.; Qiu, X. M. [Southwestern Institute of Physics, Chengdu 610041 (China); Fu, R. K. Y. [Plasma Technology Limited, Festival Walk Tower, Tat Chee Avenue, Kowloon, Hong Kong (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2013-05-28

    Breathing oscillations in the discharge of an enlarged cylindrical-anode-layer Hall plasma accelerator are investigated by three-dimensional particle-in-cell (PIC) simulation. Different from the traditional breathing mode in a circular Hall plasma accelerator, the bulk plasma oscillation here is trigged by the potential barrier generated by the concentrated ion beam and substantial enough to compete with the anode voltage. The electric field near the anode is suppressed by the potential barrier thereby decreasing the electron density by {approx}36%. The discharge is restored to the normal level after the concentrated beam explodes and then it completes one cycle of electro-driven breathing oscillation. The breathing mode identified by the PIC simulation has a frequency range of {approx}156 kHz-{approx}250 kHz and does not vary monotonically with the discharge voltage.

  5. A structural investigation of compositionally graded InAs/sub 1-x/Sb/sub x/ buffer layers

    International Nuclear Information System (INIS)

    Biefeld, R.M.

    1988-01-01

    The structures prepared in this work consisted of the InSb substrate, an initial InSb epitaxial layer, a buffer layer and an uppermost superlattice. The buffer layers were of four types: 1) a constant composition layer; 2) a step-graded layer consisting of three or five equal thickness, constant composition layers; 3) a continuously graded layer where x increased exponentially with layer thickness and 4) a continuously graded layer in which x increased linearly with layer thickness. The compositions were determined from double-crystal x-ay rocking curves using the (004) and (115) reflections. The strain distribution and layer thickness of both the buffer layers and the SLS's were obtained using a kinematical model as previously described. The surface morphologies were examined by Nomarski interference contrast microscopy. The distribution of dislocations in the buffer layers was investigated by transmission electron microscopy. The surface morphologies of the samples grown on thick, continuously graded buffer layers showed the presence of the normal cross hatching which is typical of mismatched layers which contain dislocations. However, the surfaces which contained thin buffers or buffers with abrupt compositional steps indicated the presence of microcracks. When a critical layer thickness was exceeded for a particular mismatch, microcracks formed in the samples. The thicker, continuously graded buffer layers apparently allow enough dislocations to form during the layer growth so that the critical layer thickness for crack formation is never exceeded. In contrast, not enough dislocations are formed in the thinner layers to prevent the critical layer thickness for crack formation from being exceeded

  6. Alternative buffer layer development in Cu(In,Ga)Se2 thin film solar cells

    Science.gov (United States)

    Xin, Peipei

    Cu(In,Ga)Se2-based thin film solar cells are considered to be one of the most promising photovoltaic technologies. Cu(In,Ga)Se2 (CIGS) solar devices have the potential advantage of low-cost, fast fabrication by using semiconductor layers of only a few micrometers thick and high efficiency photovoltaics have been reported at both the cell and the module levels. CdS via chemical bath deposition (CBD) has been the most widely used buffer option to form the critical junction in CIGS-based thin film photovoltaic devices. However, the disadvantages of CdS can’t be ignored - regulations on cadmium usage are getting stricter primarily due to its toxicity and environmental impacts, and the proper handling of the large amount of toxic chemical bath waste is a massive and expensive task. This dissertation is devoted to the development of Cd-free alternative buffer layers in CIGS-based thin film solar cells. Based on the considerations of buffer layer selection criteria and extensive literature review, Zn-compound buffer materials are chosen as the primary investigation candidates. Radio frequency magnetron sputtering is the preferred buffer deposition approach since it’s a clean and more controllable technique compared to CBD, and is readily scaled to large area manufacturing. First, a comprehensive study of the ZnSe1-xOx compound prepared by reactive sputtering was completed. As the oxygen content in the reactive sputtering gas increased, ZnSe1-xOx crystallinity and bandgap decreased. It’s observed that oxygen miscibility in ZnSe was low and a secondary phase formed when the O2 / (O2 + Ar) ratio in the sputtering gas exceeded 2%. Two approaches were proposed to optimize the band alignment between the CIGS and buffer layer. One method focused on the bandgap engineering of the absorber, the other focused on the band structure modification of the buffer. As a result, improved current of the solar cell was achieved although a carrier transport barrier at the junction

  7. Benzocyclobutene (BCB) Polymer as Amphibious Buffer Layer for Graphene Field-Effect Transistor.

    Science.gov (United States)

    Wu, Yun; Zou, Jianjun; Huo, Shuai; Lu, Haiyan; Kong, Yuecan; Chen, Tangshen; Wu, Wei; Xu, Jingxia

    2015-08-01

    Owing to the scattering and trapping effects, the interfaces of dielectric/graphene or substrate/graphene can tailor the performance of field-effect transistor (FET). In this letter, the polymer of benzocyclobutene (BCB) was used as an amphibious buffer layer and located at between the layers of substrate and graphene and between the layers of dielectric and graphene. Interestingly, with the help of nonpolar and hydrophobic BCB buffer layer, the large-scale top-gated, chemical vapor deposited (CVD) graphene transistors was prepared on Si/SiO2 substrate, its cutoff frequency (fT) and the maximum cutoff frequency (fmax) of the graphene field-effect transistor (GFET) can be reached at 12 GHz and 11 GHz, respectively.

  8. Methods of producing free-standing semiconductors using sacrificial buffer layers and recyclable substrates

    Science.gov (United States)

    Ptak, Aaron Joseph; Lin, Yong; Norman, Andrew; Alberi, Kirstin

    2015-05-26

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices. The low-defect density semiconductor materials produced using this method result in the enhanced performance of the semiconductor devices that incorporate the semiconductor materials.

  9. Simulation studies on the effect of a buffer layer on the external ...

    Indian Academy of Sciences (India)

    Wintec

    Device modeling of p–i–n junction amorphous silicon solar cells has been carried out using the amorphous semiconductor ... of a buffer layer in between the p- and i-layers of the p–i–n solar cell on the external parameters such as dark current density and open circuit ... Voc = nkT/q[ln(Jsc/Jo) + 1]. (2). Since it is evident from ...

  10. Evaluation of double-layer density modulated Si thin films as Li-ion battery anodes

    Science.gov (United States)

    Taha Demirkan, Muhammed; Yurukcu, Mesut; Dursun, Burcu; Demir-Cakan, Rezan; Karabacak, Tansel

    2017-10-01

    Double-layer density modulated silicon thin films which contain alternating low and high density Si film layers were fabricated by magnetron sputtering. Two different samples consisting of alternating layers of high-density/low-density and low-density/high-density Si thin film layers were investigated as anode electrodes in Li-ion batteries. Si thin film in which the terminating layer at the top is low density Si layer-quoted as low-density/high-density film (LD/HD)- exhibits better performance than Si thin film that has high density layer at the top, -quoted as high-density/low-density (HD/LD). A highly stabilized cycling performance with the specific charge capacities of 2000 mAh g‑1 at the 150th cycle at C/2 current density, and 1200 mAh g‑1 at the 240th cycle at 10 C current density were observed for the LD/HD Si anode in the presence of fluoroethylene carbonate (FEC) electrolyte additive.

  11. High-performance anode for Polymer Electrolyte Membrane Fuel Cells by multiple-layer Pt sputter deposition

    Science.gov (United States)

    Natarajan, Sadesh Kumar; Hamelin, Jean

    We investigate the sputtering deposition as a tool for preparing Polymer Electrolyte Membrane Fuel Cell (PEMFC) electrodes with improved performance and catalyst utilization. Anodes of PEMFC with ultra-low loading of Pt (0.05 mg cm -2) are developed by alternate sputtering of Pt and painting layers of carbon nanotube ink with Nafion directly on the gas diffusion layer. Sputter depositing alternate layers of Pt on carbon-Nafion layer (CNL) has increased the anode activity over single-layer Pt deposited anode due to improved porosity and the presence of Pt nanoparticles in the inner CNL. Also, we investigated the influence of Nafion content in the CNL. The optimal Nafion content giving less resistance and better performance in an anode is 29 wt.%. This is significantly lower than for standard MEA anodes, indicating sufficient interfacial contact between each CNL. We studied the anodes prepared with 50 wt.% Nafion, which revealed larger ohmic resistance and also, blocks the CNL pores reducing gas permeability. Excellent mass transfer and performance is obtained with three-layer Pt sputter deposited anode with CNL containing 29 wt.% of Nafion.

  12. The roles of buffer layer thickness on the properties of the ZnO epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Kun, E-mail: ktang@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Huang, Shimin [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Gu, Shulin, E-mail: slgu@nju.edu.cn [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Zhu, Shunming [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Ye, Jiandong [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China); Nanjing University Institute of Optoelectronics at Yangzhou, Yangzhou 225009 (China); Xu, Zhonghua; Zheng, Youdou [Nanjing National Laboratory of Microstructures and School of Electronic Science and Engineering, Nanjing University, Nanjing 210023 (China)

    2016-12-01

    Highlights: • The growth mechanism has been revealed for the ZnO buffers with different thickness. • The surface morphology has been determined as the key factor to affect the epitaxial growth. • The relation between the hexagonal pits from buffers and epi-films has been established. • The hexagonal pits formed in the epi-films have been attributed to the V-shaped defects inheriting from the dislocations in the buffers. • The structural and electrical properties of the V-defects have been presented and analyzed. - Abstract: In this article, the authors have investigated the optimization of the buffer thickness for obtaining high-quality ZnO epi-films on sapphire substrates. The growth mechanism of the buffers with different thickness has been clearly revealed, including the initial nucleation and vertical growth, the subsequent lateral growth with small grain coalescence, and the final vertical growth along the existing larger grains. Overall, the quality of the buffer improves with increasing thickness except the deformed surface morphology. However, by a full-scale evaluation of the properties for the epi-layers, the quality of the epi-film is briefly determined by the surface morphology of the buffer, rather than the structural, optical, or electrical properties of it. The best quality epi-layer has been grown on the buffer with a smooth surface and well-coalescent grains. Meanwhile, due to the huge lattice mismatch between sapphire and ZnO, dislocations are inevitably formed during the growth of buffers. More importantly, as the film grows thicker, the dislocations may attracting other smaller dislocations and defects to reduce the total line energy and thus result in the formation of V-shape defects, which are connected with the bottom of the threading dislocations in the buffers. The V-defects appear as deep and large hexagonal pits from top view and they may act as electron traps which would affect the free carrier concentration of the epi-layers.

  13. The roles of buffer layer thickness on the properties of the ZnO epitaxial films

    International Nuclear Information System (INIS)

    Tang, Kun; Huang, Shimin; Gu, Shulin; Zhu, Shunming; Ye, Jiandong; Xu, Zhonghua; Zheng, Youdou

    2016-01-01

    Highlights: • The growth mechanism has been revealed for the ZnO buffers with different thickness. • The surface morphology has been determined as the key factor to affect the epitaxial growth. • The relation between the hexagonal pits from buffers and epi-films has been established. • The hexagonal pits formed in the epi-films have been attributed to the V-shaped defects inheriting from the dislocations in the buffers. • The structural and electrical properties of the V-defects have been presented and analyzed. - Abstract: In this article, the authors have investigated the optimization of the buffer thickness for obtaining high-quality ZnO epi-films on sapphire substrates. The growth mechanism of the buffers with different thickness has been clearly revealed, including the initial nucleation and vertical growth, the subsequent lateral growth with small grain coalescence, and the final vertical growth along the existing larger grains. Overall, the quality of the buffer improves with increasing thickness except the deformed surface morphology. However, by a full-scale evaluation of the properties for the epi-layers, the quality of the epi-film is briefly determined by the surface morphology of the buffer, rather than the structural, optical, or electrical properties of it. The best quality epi-layer has been grown on the buffer with a smooth surface and well-coalescent grains. Meanwhile, due to the huge lattice mismatch between sapphire and ZnO, dislocations are inevitably formed during the growth of buffers. More importantly, as the film grows thicker, the dislocations may attracting other smaller dislocations and defects to reduce the total line energy and thus result in the formation of V-shape defects, which are connected with the bottom of the threading dislocations in the buffers. The V-defects appear as deep and large hexagonal pits from top view and they may act as electron traps which would affect the free carrier concentration of the epi-layers.

  14. Final Report: Rational Design of Wide Band Gap Buffer Layers for High-Efficiency Thin-Film Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Lordi, Vincenzo [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-09-30

    The main objective of this project is to enable rational design of wide band gap buffer layer materials for CIGS thin-film PV by building understanding of the correlation of atomic-scale defects in the buffer layer and at the buffer/absorber interface with device electrical properties. Optimized wide band gap buffers are needed to reduce efficiency loss from parasitic absorption in the buffer. The approach uses first-principles materials simulations coupled with nanoscale analytical electron microscopy as well as device electrical characterization. Materials and devices are produced by an industrial partner in a manufacturing line to maximize relevance, with the goal of enabling R&D of new buffer layer compositions or deposition processes to push device efficiencies above 21%. Cadmium sulfide (CdS) is the reference material for analysis, as the prototypical high-performing buffer material.

  15. Impedance analysis of the multilayered organic solar cells with and without hole buffer layer

    Science.gov (United States)

    Itoh, Eiji; Nakagoshi, Satoru

    2014-01-01

    We studied the effects of a buffer layer [molybdenum oxide (MoO3) and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)] and the thickness of a p-type tetraphenyldibenzoperiflanthene (DBP) layer on the performance of multilayered organic solar cells in indium-tin oxide (ITO)/buffer/DBP/fullerene C60/bathocuproine (BCP)/Al multilayered photovoltaic devices. The insertion of a hole buffer layer reduced the resistance across the cell in forward biasing under illumination and in the dark, and the negative capacitance behaviors were observed at a voltage higher than VOC, probably owing to the enhancement of the double injection. On the other hand, a hole-blocking ITO/DBP interface reduced the hole injection and extraction, and DBP became similar to a dielectric layer in the dark, as determined from the capacitance-frequency measurement. The photogenerated carriers caused an increase in the capacitance C and the conductance G in the devices with and without the MoO3 buffer layers. Both C and G reached their local minima at a voltage close to VOC, and increased with a decrease in external voltage probably owing to the enhancement of charge extraction efficiency. At a lower voltage, however, C and G reached their peak values and then decreased again with a decrease in external voltage, probably owing to the reduction (ejection) in the number of photogenerated space charges in active layers. The increase in the thickness of the dielectric DBP layer resulted in a reduction in charge extraction efficiency, and an S-shaped curve was observed for the thick DBP cell. The peak voltages in C and G moved toward negative values with an increment in thickness, and this was discussed using the simplified rate equation model.

  16. Exploring Cd-Zn-O-S alloys for improved buffer layers in thin-film photovoltaics

    Science.gov (United States)

    Varley, J. B.; Lordi, V.; He, X.; Rockett, A.

    2017-07-01

    To compete with existing and more mature solar cell technologies such as crystalline Si, thin-film photovoltaics require optimization of every aspect in the device heterostructure to reach maximum efficiencies and cost effectiveness. For absorbers like CdTe, Cu(In ,Ga )Se 2 (CIGSe), and Cu2ZnSn(S ,Se ) 4 (CZTSSe), improving the n -type buffer layer partner beyond conventional CdS is one avenue that can reduce photocurrent losses and improve overall performance. Here, we use first-principles calculations based on hybrid functionals to explore alloys spanning the Cd-, Zn-, O-, and S-containing phase space to identify compositions that may be superior to common buffers like pure CdS or Zn(O,S). We address issues highly correlated with device performance such as lattice-matching for improved buffer-absorber epitaxy and interface quality, dopability, the band gap for reduced absorption losses in the buffer, and the conduction-band offsets shown to facilitate improved charge separation from photoexcited carriers. We supplement our analysis with device-level simulations as parameterized from our calculations and real devices to assess our conclusions of low-Zn and O content buffers showing improved performance with respect to CdS buffers.

  17. In-depth porosity control of mesoporous silicon layers by an anodization current adjustment

    Science.gov (United States)

    Lascaud, J.; Defforge, T.; Certon, D.; Valente, D.; Gautier, G.

    2017-12-01

    The formation of thick mesoporous silicon layers in P+-type substrates leads to an increase in the porosity from the surface to the interface with silicon. The adjustment of the current density during the electrochemical etching of porous silicon is an intuitive way to control the layer in-depth porosity. The duration and the current density during the anodization were varied to empirically model porosity variations with layer thickness and build a database. Current density profiles were extracted from the model in order to etch layer with in-depth control porosity. As a proof of principle, an 80 μm-thick porous silicon multilayer was synthetized with decreasing porosities from 55% to 35%. The results show that the assessment of the in-depth porosity could be significantly enhanced by taking into account the pure chemical etching of the layer in the hydrofluoric acid-based electrolyte.

  18. Multi-filamentary REBCO tapes fabricated by scratching a buffer layer along the tape longitudinal direction

    Energy Technology Data Exchange (ETDEWEB)

    Kurihara, Chihaya, E-mail: chihaya.kurihara@jp.fujikura.com [Fujikura Ltd., 1440, Mutsuzaki, Sakura, Chiba 285-8550 (Japan); Fujita, Shinji; Nakamura, Naonori; Igarashi, Mitsunori; Iijima, Yasuhiro [Fujikura Ltd., 1440, Mutsuzaki, Sakura, Chiba 285-8550 (Japan); Higashikawa, Kohei; Uetsuhara, Dai; Kiss, Takanobu; Iwakuma, Masataka [Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka 819-0395 (Japan)

    2016-11-15

    Highlights: • We developed new method of slitting tape between buffer layer processes for multi-filamentary tape. • By scratching buffer layer along the tape longitudinal direction, we find that REBCO layer is divided easily without damaging it. • We have developed 100 m class multi-filamentary REBCO tapes which are suitable for superconducting coils. - Abstract: A method for making multi-filamentary REBCO tapes by only scratching buffer layer was developed for coil application which requires accurate magnetic fields. By continuous I{sub c} measurement, we found that our new multi-filamentary tape could provide almost equal I{sub c} compared to conventional tapes. Then, using EBSD and RTR-SHPM methods, a divided structure of REBCO layer was surely confirmed. AC loss was also decreased. Furthermore, the result of delamination test of our new multi-filamentary tape showed enough mechanical property. As a result, we have succeeded in developing 100 m class multi-filamentary tape for superconducting coil.

  19. Modeling and performance analysis dataset of a CIGS solar cell with ZnS buffer layer

    Directory of Open Access Journals (Sweden)

    Md. Billal Hosen

    2017-10-01

    Full Text Available This article represents the baseline data of the several semiconductor materials used in the model of a CIGS thin film solar cell with an inclusion of ZnS buffer layer. As well, input parameters, contact layer data and operating conditions for CIGS solar cell simulation with ZnS buffer layer have been described. The schematic diagram of photovoltaic solar cell has been depicted. Moreover, the most important performance measurement graph, J-V characteristic curve, resulting from CIGS solar cell simulation has been analyzed to estimate the optimum values of fill factor and cell efficiency. These optimum results have been obtained from the open circuit voltage, short circuit current density, and the maximum points of voltage and current density generated from the cell.

  20. Efficient small-molecule organic solar cells incorporating a doped buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Dei-Wei [Department of aviation and Communication Electronics, Air Force Institute of Technology, Kaohsiung 820, Taiwan (China); Chen, Kan-Lin [Department of Electronic Engineering, Fortune Institute of Technology, Kaohsiung 831, Taiwan (China); Huang, Chien-Jung, E-mail: chien@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Nanzih, Kaohsiung 811, Taiwan (China); Tsao, Yao-Jen [Department of Applied Physics, National University of Kaohsiung, Nanzih, Kaohsiung 811, Taiwan (China); Chen, Wen-Ray; Meen, Teen-Hang [Department of Electronic Engineering, National Formosa University, Hu-Wei, Yunlin 632, Taiwan (China)

    2013-06-01

    Small-molecule organic solar cells (OSCs) with an optimized structure of indium tin oxide/poly (3,4-ethylenedioxythioxythiophene):poly(styrenesulfonate)/copper phthalocyanine (CuPc) (10 nm)/CuPc: fullerene (C{sub 60}) mixed (20 nm)/C{sub 60} (20 nm)/4,7-diphenyl-1,10-phenanthroline (BPhen) (5 nm)/Ag were fabricated. In this study, the cesium carbonate-doped BPhen (Cs{sub 2}CO{sub 3}:BPhen) was adopted as the buffer layer to enhance the efficiency of the OSCs. The photovoltaic parameters of the OSCs, such as the short-circuit current density and fill factor, depend on the doping concentration of Cs{sub 2}CO{sub 3} in the BPhen layer. The cell with a Cs{sub 2}CO{sub 3}:BPhen (1:4) cathode buffer layer exhibits a power conversion efficiency (PCE) of 3.51%, compared to 3.37% for the device with the pristine BPhen layer. The enhancement of PCE was attributed to the energy-level alignment between the C{sub 60} layer and the Cs{sub 2}CO{sub 3}:BPhen layer. In addition, the characterization measured using atomic force microscopy shows that the Cs{sub 2}CO{sub 3}:BPhen layers have smoother surfaces. - Highlight: • Cs2CO3-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) cathode buffer layer. • Cs2CO3:BPhen layer with different ratios affects organic solar cells performance. • Cell with 1:4 (Cs2CO3:BPhen) ratio shows 3.51% power conversion efficiency.

  1. Effect of Cu buffer layer on magnetic anisotropy of cobalt thin films deposited on MgO(001 substrate

    Directory of Open Access Journals (Sweden)

    Syed Sheraz Ahmad

    2016-11-01

    Full Text Available Cobalt thin films with 5 nm thickness were prepared on single-crystal MgO (001 substrates with different thickness Cu buffer (0 nm, 5 nm, 10 nm, 20 nm. The structure, magnetic properties and transport behaviors were investigated by employing low-energy-electron-diffraction (LEED, magneto-optical Kerr effect (MOKE and anisotropic magnetoresistance (AMR. By comparing the magnetic properties of the sample as-deposited (without Cu buffer layer one with those having the buffer Cu, we found that the magnetic anisotropy was extremely affected by the Cu buffer layer. The magnetic anisotropy of the as-deposited, without buffer layer, sample shows the uniaxial magnetic anisotropy (UMA. We found that the symmetry of the magnetic anisotropy is changed from UMA to four-fold when the thickness of the Cu buffer layer reaches to 20 nm. Meanwhile, the coercivity increased from 49 Oe (without buffer layer to 300 Oe (with 20 nm Cu buffer, in the easy axis direction, as the thickness of the buffer layer increases. Moreover, the magnitudes of various magnetic anisotropy constants were determined from torque curves on the basis of AMR results. These results support the phenomenon shown in the MOKE.

  2. Solution-processed In2S3 buffer layer for chalcopyrite thin film solar cells

    Directory of Open Access Journals (Sweden)

    Wang Lan

    2016-01-01

    Full Text Available We report a route to deposit In2S3 thin films from air-stable, low-cost molecular precursor inks for Cd-free buffer layers in chalcopyrite-based thin film solar cells. Different precursor compositions and processing conditions were studied to define a reproducible and robust process. By adjusting the ink properties, this method can be applied in different printing and coating techniques. Here we report on two techniques, namely spin-coating and inkjet printing. Active area efficiencies of 12.8% and 12.2% have been achieved for In2S3-buffered solar cells respectively, matching the performance of CdS-buffered cells prepared with the same batch of absorbers.

  3. Solution-processed In2S3 buffer layer for chalcopyrite thin film solar cells

    Science.gov (United States)

    Wang, Lan; Lin, Xianzhong; Ennaoui, Ahmed; Wolf, Christian; Lux-Steiner, Martha Ch.; Klenk, Reiner

    2016-02-01

    We report a route to deposit In2S3 thin films from air-stable, low-cost molecular precursor inks for Cd-free buffer layers in chalcopyrite-based thin film solar cells. Different precursor compositions and processing conditions were studied to define a reproducible and robust process. By adjusting the ink properties, this method can be applied in different printing and coating techniques. Here we report on two techniques, namely spin-coating and inkjet printing. Active area efficiencies of 12.8% and 12.2% have been achieved for In2S3-buffered solar cells respectively, matching the performance of CdS-buffered cells prepared with the same batch of absorbers.

  4. Environmental Modeling, The Natural Filter Buffer Targeting layers identify riparian forest and grass buffer opportunities by county. Land use and hydrology characteristics were used to identify potential riparian buffer locations., Published in 2014, Smaller than 1:100000 scale, Maryland Department of Natural Resources (DNR).

    Data.gov (United States)

    NSGIC Education | GIS Inventory — Environmental Modeling dataset current as of 2014. The Natural Filter Buffer Targeting layers identify riparian forest and grass buffer opportunities by county. Land...

  5. Environmental Modeling, The Buffer Priority layers for Phosphorus / Sediment) Removal identify priority forest/grass buffer opportunities by subwatershed. Land use, hydrology, soil, and landscape characteristics were analyzed to rank buffer opportunities with high P/sed removal., Published in 2014, Smaller than 1:100000 scale, Maryland Department of Natural Resources (DNR).

    Data.gov (United States)

    NSGIC Education | GIS Inventory — Environmental Modeling dataset current as of 2014. The Buffer Priority layers for Phosphorus / Sediment) Removal identify priority forest/grass buffer opportunities...

  6. Solution-processed In2S3 buffer layer for chalcopyrite thin film solar cells

    OpenAIRE

    Wang Lan; Lin Xianzhong; Ennaoui Ahmed; Wolf Christian; Lux-Steiner Martha Ch.; Klenk Reiner

    2016-01-01

    We report a route to deposit In2S3 thin films from air-stable, low-cost molecular precursor inks for Cd-free buffer layers in chalcopyrite-based thin film solar cells. Different precursor compositions and processing conditions were studied to define a reproducible and robust process. By adjusting the ink properties, this method can be applied in different printing and coating techniques. Here we report on two techniques, namely spin-coating ...

  7. ZnS/Zn(O,OH)S-based buffer layer deposition for solar cells

    Science.gov (United States)

    Bhattacharya, Raghu N [Littleton, CO

    2009-11-03

    The invention provides CBD ZnS/Zn(O,OH)S and spray deposited ZnS/Zn(O,OH)S buffer layers prepared from a solution of zinc salt, thiourea and ammonium hydroxide dissolved in a non-aqueous/aqueous solvent mixture or in 100% non-aqueous solvent. Non-aqueous solvents useful in the invention include methanol, isopropanol and triethyl-amine. One-step deposition procedures are described for CIS, CIGS and other solar cell devices.

  8. Non-Toxic Buffer Layers in Flexible Cu(In,GaSe2 Photovoltaic Cell Applications with Optimized Absorber Thickness

    Directory of Open Access Journals (Sweden)

    Md. Asaduzzaman

    2017-01-01

    Full Text Available Absorber layer thickness gradient in Cu(In1−xGaxSe2 (CIGS based solar cells and several substitutes for typical cadmium sulfide (CdS buffer layers, such as ZnS, ZnO, ZnS(O,OH, Zn1−xSnxOy (ZTO, ZnSe, and In2S3, have been analyzed by a device emulation program and tool (ADEPT 2.1 to determine optimum efficiency. As a reference type, the CIGS cell with CdS buffer provides a theoretical efficiency of 23.23% when the optimum absorber layer thickness was determined as 1.6 μm. It is also observed that this highly efficient CIGS cell would have an absorber layer thickness between 1 μm and 2 μm whereas the optimum buffer layer thickness would be within the range of 0.04–0.06 μm. Among all the cells with various buffer layers, the best energy conversion efficiency of 24.62% has been achieved for the ZnO buffer layer based cell. The simulation results with ZnS and ZnO based buffer layer materials instead of using CdS indicate that the cell performance would be better than that of the CdS buffer layer based cell. Although the cells with ZnS(O,OH, ZTO, ZnSe, and In2S3 buffer layers provide slightly lower efficiencies than that of the CdS buffer based cell, the use of these materials would not be deleterious for the environment because of their non-carcinogenic and non-toxic nature.

  9. Electrically conducting oxide buffer layers on biaxially textured nickel alloy tapes by reel-to-reel MOCVD process

    International Nuclear Information System (INIS)

    Stadel, O; Samoilenkov, S V; Muydinov, R Yu; Schmidt, J; Keune, H; Wahl, G; Gorbenko, O Yu; Korsakov, I E; Melnikov, O V; Kaul, A R

    2006-01-01

    Reel-to-reel MOCVD process for continuous growth of electrically conducting buffer layers on biaxially textured Ni5W tapes has been developed. The new buffer layer architechture is presented: 200 nm (La, Ba) 2 CuO 4 /40 nm (La, Ba)MnO 3 /Ni5W. Constituting layers with high structural quality have been grown on moving tapes (in plane FWHM ≤ 6 0 and out of plane FWHM ≤ 3 0 )

  10. Growth and characterization of CdS buffer layers by CBD and MOCVD

    International Nuclear Information System (INIS)

    Morrone, A.A.; Huang, C.; Li, S.S.

    1999-01-01

    Thin film CdS has been widely used in thin-film photovoltaic devices. The most efficient Cu(In,ampersand h;Ga)Se 2 (CIGS) solar cells reported to date utilized a thin CdS buffer layer prepared by a reactive solution growth technique known as chemical bath deposition (CBD). Considerable effort has been directed to better understand the role and find a replacement for the CBD CdS process in CIGS-based solar cells. We reported a low temperature (∼150 and h;degree C) Metalorganic Chemical Vapor Deposition (MOCVD) CdS thin film buffer layer process for CIGS absorbers. Many prior studies have reported that CBD CdS contains a mixture of crystal structures. Recent investigations of CBD CdS thin films by ellipsometry suggested a multilayer structure. In this study we compare CdS thin films prepared by CBD and MOCVD and the effects of annealing. TED and XRD are used to characterize the crystal structure, the film microstructure is studied by HRTEM, and the optical properties are studied by Raman and spectrophotometry. All of these characterization techniques reveal superior crystalline film quality for CdS films grown by MOCVD compared to those grown by CBD. Dual Beam Optical Modulation (DBOM) studies showed that the MOCVD and CBD CdS buffer layer processes have nearly the same effect on CIGS absorbers when combined with a cadmium partial electrolyte aqueous dip. copyright 1999 American Institute of Physics

  11. Improvement of the interfacial Dzyaloshinskii-Moriya interaction by introducing a Ta buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam-Hui; Jung, Jinyong; Cho, Jaehun; You, Chun-Yeol, E-mail: cyyou@inha.ac.kr [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of); Han, Dong-Soo; Kim, June-Seo, E-mail: spin2mtj@gmail.com; Swagten, Henk J. M. [Department of Applied Physics, Center for NanoMaterials, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands)

    2015-10-05

    We report systematic measurements of the interfacial Dzyaloshinskii-Moriya interaction (iDMI) by employing Brillouin light scattering in Pt/Co/AlO{sub x} and Ta/Pt/Co/AlO{sub x} structures. By introducing a tantalum buffer layer, the saturation magnetization and the interfacial perpendicular magnetic anisotropy are significantly improved due to the better interface between heavy metal and ferromagnetic layer. From the frequency shift between Stokes- and anti-Stokes spin-waves, we successively obtain considerably larger iDM energy densities (D{sub max} = 1.65 ± 0.13 mJ/m{sup 2} at t{sub Co} = 1.35 nm) upon adding the Ta buffer layer, despite the nominally identical interface materials. Moreover, the energy density shows an inverse proportionality with the Co layer thickness, which is the critical clue that the observed iDMI is indeed originating from the interface between the Pt and Co layers.

  12. Effect of electrolyte temperature on the thickness of anodic aluminium oxide (AAO layer

    Directory of Open Access Journals (Sweden)

    P. Michal

    2016-07-01

    Full Text Available Effect of electrolyte temperature on the thickness of resulting oxide layer has been studied. Unlike previous published studies this article was aimed to monitor the relationship between electrolyte temperature and resulting AAO layer thickness in interaction with other input factors affecting during anodizing process under special process condition, i.e. lower concentration of sulphuric acid, oxalic acid, boric acid and sodium chloride. According to Design of Experiments (DOE 80 individual test runs of experiment were carried out. Using statistical analysis and artificial intelligence for evaluation, the computational model predicting the thickness of oxide layer in the range from 5 / μm to 15 / μm with tolerance ± 0,5 / μm was developed.

  13. Effects of sic buffer layer on the optical properties of ZnO films grown on Si (1 1 1) substrates

    International Nuclear Information System (INIS)

    Zhang Yang; Zheng Haiwu; Su Jianfeng; Lin Bixi; Fu Zhuxi

    2007-01-01

    ZnO films have been grown by a sol-gel process on Si (1 1 1) substrates with and without SiC buffer layers. The influence of SiC buffer layer on the optical properties of ZnO films grown on Si (1 1 1) substrates was investigated. The intensity of the E 2 (high) phonon peak in the micro-Raman spectrum of ZnO film with the SiC buffer layer is stronger than that of the sample without the SiC buffer layer, and the breadth of E 2 (high) phonon peak of ZnO film with the SiC buffer layer is narrower than that of the sample without the SiC buffer layer. These results indicated that the crystalline quality of the sample with the SiC buffer layer is better than that of the sample without the SiC buffer layer. In photoluminescence spectra, the intensity of free exciton emission from ZnO films with the SiC buffer was much stronger than that from ZnO film without the SiC buffer layer, while the intensity of deep level emission from sample with the SiC buffer layer was about half of that of sample without the SiC buffer layer. The results indicate the SiC buffer layer improves optical qualities of ZnO films on Si (1 1 1) substrates

  14. Double-layer anti-reflection coating containing a nanoporous anodic aluminum oxide layer for GaAs solar cells.

    Science.gov (United States)

    Yang, Tianshu; Wang, Xiaodong; Liu, Wen; Shi, Yanpeng; Yang, Fuhua

    2013-07-29

    Multilayer anti-reflection (AR) coatings can be used to improve the efficiency of Gallium Arsenide (GaAs) solar cells. We propose an alternate method to obtain optical thin films with specified refractive indices, which is using a self-assembled nanoporous anodic aluminum oxide (AAO) template as an optical thin film whose effective refractive index can be tuned by pore-widening. Different kinds of double-layer AR coatings each containing an AAO layer were designed and investigated by finite difference time domain (FDTD) method. We demonstrate that a λ /4n - λ /4n AR coating consisting of a TiO(2) layer and an AAO layer whose effective refractive index is 1.32 realizes a 96.8% light absorption efficiency of the GaAs solar cell under AM1.5 solar spectrum (400 nm-860 nm). We also have concluded some design principles of the double-layer AR coating containing an AAO layer for GaAs solar cells.

  15. Double-layered buffer to enhance the thermal performance in a high-level radioactive waste disposal system

    International Nuclear Information System (INIS)

    Choi, Heui-Joo; Choi, Jongwon

    2008-01-01

    A thermal performance is one of the most important factors in the design of a geological disposal system for high-level radioactive wastes. According to the conceptual design of the Korean Reference disposal System, the maximum temperature of its buffer with a domestic Ca-bentonite is close to the thermal criterion, 100 deg. C. In order to improve the thermal conductivity of its buffer, several kinds of additives are compared. Among the additives, graphite shows the best result in that the thermal conductivity of the bentonite block is more than 2.0 W/m deg. C. We introduced the concept of a double-layered buffer instead of a traditional bentonite block in order to use the applied additive more effectively. The thermal analysis, based upon the three-dimensional finite element method, shows that a double-layered buffer could reduce the maximum temperature on a canister's surface by 7 deg. C under identical conditions when compared with a single-layered buffer. An analytical solution was derived to efficiently analyze the effects of a double-layered buffer. The illustrative cases show that the temperature differences due to a double-layered buffer depend on the thickness of the buffer

  16. Increased Power in Sediment Microbial Fuel Cell: Facilitated Mass Transfer via a Water-Layer Anode Embedded in Sediment.

    Directory of Open Access Journals (Sweden)

    Yoo Seok Lee

    Full Text Available We report a methodology for enhancing the mass transfer at the anode electrode of sediment microbial fuel cells (SMFCs, by employing a fabric baffle to create a separate water-layer for installing the anode electrode in sediment. The maximum power in an SMFC with the anode installed in the separate water-layer (SMFC-wFB was improved by factor of 6.6 compared to an SMFC having the anode embedded in the sediment (SMFC-woFB. The maximum current density in the SMFC-wFB was also 3.9 times higher (220.46 mA/m2 than for the SMFC-woFB. We found that the increased performance in the SMFC-wFB was due to the improved mass transfer rate of organic matter obtained by employing the water-layer during anode installation in the sediment layer. Acetate injection tests revealed that the SMFC-wFB could be applied to natural water bodies in which there is frequent organic contamination, based on the acetate flux from the cathode to the anode.

  17. Increased Power in Sediment Microbial Fuel Cell: Facilitated Mass Transfer via a Water-Layer Anode Embedded in Sediment.

    Science.gov (United States)

    Lee, Yoo Seok; An, Junyeong; Kim, Bongkyu; Park, HyunJun; Kim, Jisu; Chang, In Seop

    2015-01-01

    We report a methodology for enhancing the mass transfer at the anode electrode of sediment microbial fuel cells (SMFCs), by employing a fabric baffle to create a separate water-layer for installing the anode electrode in sediment. The maximum power in an SMFC with the anode installed in the separate water-layer (SMFC-wFB) was improved by factor of 6.6 compared to an SMFC having the anode embedded in the sediment (SMFC-woFB). The maximum current density in the SMFC-wFB was also 3.9 times higher (220.46 mA/m2) than for the SMFC-woFB. We found that the increased performance in the SMFC-wFB was due to the improved mass transfer rate of organic matter obtained by employing the water-layer during anode installation in the sediment layer. Acetate injection tests revealed that the SMFC-wFB could be applied to natural water bodies in which there is frequent organic contamination, based on the acetate flux from the cathode to the anode.

  18. Use of a Soluble Anode in Electrodeposition of Thick Bismuth Telluride Layers

    Science.gov (United States)

    Maas, M.; Diliberto, S.; de Vaulx, C.; Azzouz, K.; Boulanger, C.

    2014-10-01

    Integration of thermoelectric devices within an automotive heat exchanger could enable conversion of lost heat into electrical energy, contributing to improved total output from the engine. For this purpose, synthesis of thick bismuth telluride (Bi2Te3) films is required. Bismuth telluride has been produced by an electrochemical method in nitric acid with a sacrificial bismuth telluride anode as the source of cations. The binary layer grows on the working electrode while the counter-electrode, a Bi2Te3 disk obtained by high frequency melting, is oxidized to BiIII and TeIV. This process leads to auto-regeneration of the solution without modification of its composition. The thickness of films deposited by use of the Bi2Te3 anode was approximately 10 times that without. To demonstrate the utility of a soluble anode in electrochemical deposition, we report characterization of the composition and morphology of the films obtained under different experimental conditions. Perfectly dense and regular Bi2Te3 films (˜400 μm) with low internal stress and uniform composition across the cross-section were prepared. Their thermoelectric properties were assessed.

  19. Effects of buffer layer temperature on the magnetic properties of NdFeB thin film magnets

    International Nuclear Information System (INIS)

    Kim, Y.B.; Cho, S.H.; Kim, H.T.; Ryu, K.S.; Lee, S.H.; Lee, K.H.; Kapustin, G.A.

    2004-01-01

    Effects of the buffer layer temperature (T b ) on the magnetic properties and microstructure of [Mo/NdFeB/Mo]-type thin films have been investigated. The Mo-buffer layer with low T b is composed of fine grains while that with high T b has coarse grains. The subsequent NdFeB layer also grows with fine or coarse grains following the buffer layer structure. The NdFeB layer grown on a low T b buffer shows high coercivity and strong perpendicular anisotropy. The best magnetic properties of i H c =1.01 MA/m (12.7 kOe), B r =1.31 T (13.1 kG) and BH max =329 kJ/m 3 (41.4 MGOe) were obtained from the film with T b =400 deg. C

  20. Investigation of CeO2 Buffer Layer Effects on the Voltage Response of YBCO Transition-Edge Bolometers

    DEFF Research Database (Denmark)

    Mohajeri, Roya; Nazifi, Rana; Wulff, Anders Christian

    2016-01-01

    The effect on the thermal parameters of superconducting transition-edge bolometers produced on a single crystalline SrTiO3 (STO) substrate with and without a CeO2 buffer layer was investigated. Metal-organic deposition was used to deposit the 20-nm CeO2 buffer layer, whereas RF magnetron sputtering...... responses, and the results were compared with that of simulations conducted by applying a one-dimensional thermophysical model. It was observed that adding the buffer layer to the structure of the bolometer results in an increased response at higher modulation frequencies. Results from simulations made...

  1. Improvement in the Lifetime of Planar Organic Photovoltaic Cells through the Introduction of MoO3 into Their Cathode Buffer Layers

    Directory of Open Access Journals (Sweden)

    Linda Cattin

    2014-03-01

    Full Text Available Recently, MoO3, which is typically used as an anode buffer layer in organic photovoltaic cells (OPVCs, has also been used as a cathode buffer layer (CBL. Here, we check its efficiency as a CBL using a planar heterojunction based on the CuPc/C60 couple. The CBL is a bi-layer tris-(8-hydroxyquinoline aluminum (Alq3/MoO3. We show that the OPVC with MoO3 in its CBL almost immediately exhibits lower efficiency than those using Alq3 alone. Nevertheless, the OPVCs increase their efficiency during the first five to six days of air exposure. We explain this evolution of the efficiency of the OPVCs over time through the variation in the MoO3 work function due to air contamination. By comparison to a classical OPVC using a CBL containing only Alq3, if it is found that the initial efficiency of the latter is higher, this result is no longer the same after one week of exposure to ambient air. Indeed, this result is due to the fact that the lifetime of the cells is significantly increased by the presence of MoO3 in the CBL.

  2. Influence of electrical parameters on morphology of nanostructured TiO2 layers developed by electrochemical anodization

    Directory of Open Access Journals (Sweden)

    Strnad Gabriela

    2017-01-01

    Full Text Available Ti6Al4V alloy micro rough surfaces with TiO2 self-organized nanostructured layers were synthesized using electrochemical anodization in phosphate/fluoride electrolyte, at different end potentials (5V, 10V, 15V, and 20 V. The current – time characteristics were recorded, and the link between current evolution and the morphology of developing oxide layers was investigated. On flat surfaces of Ti6Al4V alloy we developed TiO2 layers with different morphologies (random pores, nanopores of 25…50 nm, and highly organized nanotubes of 50…100 nm in diameter depending on electrical parameters of anodization process. In our anodization cell, in optimized conditions, we are able to superimpose nanostructured oxide layers (nanotubular or nanoporous over micro structured surfaces of titanium based materials used for biomedical implants.

  3. High-Efficiency and Stable Organic Solar Cells Enabled by Dual Cathode Buffer Layers.

    Science.gov (United States)

    Huai, Zhaoxiang; Wang, Lixin; Sun, Yansheng; Fan, Rui; Huang, Shahua; Zhao, Xiaohui; Li, Xiaowei; Fu, Guangsheng; Yang, Shaopeng

    2018-02-14

    Various cathode interface materials have been used in organic solar cells (OSCs) to realize high performance. However, most cathode interface materials have their respective weaknesses in maximizing the efficiency or stability of OSCs. Herein, three kinds of alcohol-soluble cathode interfacial materials are combined with bathocuproine (BCP) to serve as multifunctional bilayer cathode buffers for the regular OSCs, and thus greatly enhanced power conversion efficiencies over 10.11% and significantly improved device stability have been achieved. By utilizing double interlayers, both light absorption and light distribution in active layer are improved. Furthermore, double interlayers offer favorable energy-level alignment, alcohol treatment, and duplicate protection of active layer, resulting in significantly reduced leakage current, suppressed recombination, and efficient charge collection. The improved device stability is related to the blocking effect of the complex formed between BCP and the metal electrode and the additional protection effect of the underlying alcohol-soluble materials. In view of the universal use of alcohol-soluble organic electrolyte as cathode buffer layers and by courtesy of the superiority of the double cathode layers relative to the monolayer controls, the double interlayer strategy demonstrated here opens a new way to fully exploiting the potential of OSCs and is believed to be extended to a wider application.

  4. Co-delivery of ibuprofen and gentamicin from nanoporous anodic titanium dioxide layers.

    Science.gov (United States)

    Pawlik, Anna; Jarosz, Magdalena; Syrek, Karolina; Sulka, Grzegorz D

    2017-04-01

    Although single-drug therapy may prove insufficient in treating bacterial infections or inflammation after orthopaedic surgeries, complex therapy (using both an antibiotic and an anti-inflammatory drug) is thought to address the problem. Among drug delivery systems (DDSs) with prolonged drug release profiles, nanoporous anodic titanium dioxide (ATO) layers on Ti foil are very promising. In the discussed research, ATO samples were synthesized via a three-step anodization process in an ethylene glycol-based electrolyte with fluoride ions. The third step lasted 2, 5 and 10min in order to obtain different thicknesses of nanoporous layers. Annealing the as-prepared amorphous layers at the temperature of 400°C led to obtaining the anatase phase. In this study, water-insoluble ibuprofen and water-soluble gentamicin were used as model drugs. Three different drug loading procedures were applied. The desorption-desorption-diffusion (DDD) model of the drug release was fitted to the experimental data. The effects of crystalline structure, depth of TiO 2 nanopores and loading procedure on the drug release profiles were examined. The duration of the drug release process can be easily altered by changing the drug loading sequence. Water-soluble gentamicin is released for a long period of time if gentamicin is loaded in ATO as the first drug. Additionally, deeper nanopores and anatase phase suppress the initial burst release of drugs. These results confirm that factors such as morphological and crystalline structure of ATO layers, and the procedure of drug loading inside nanopores, allow to alter the drug release performance of nanoporous ATO layers. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Annealing temperature dependence of magnetic properties of CoFeB/MgO stacks on different buffer layers

    Science.gov (United States)

    Watanabe, Kyota; Fukami, Shunsuke; Sato, Hideo; Ikeda, Shoji; Matsukura, Fumihiro; Ohno, Hideo

    2017-08-01

    We investigate the annealing temperature dependence of the magnetic properties of CoFeB/MgO stacks with different buffer materials (Mo, Ta, and W). For Mo and W, bcc-crystalline and amorphous-like films are prepared by changing the deposition conditions. A relatively small saturation magnetization is maintained after annealing up to 400 °C for the samples with bcc-W, bcc-Mo, and amorphous-like Mo buffers. A small variation in magnetic dead layer thickness with annealing is observed for the samples with bcc-crystalline buffer layers. The interfacial anisotropy is found to mainly depend on the element of the buffer layer used regardless of its crystalline structure, and is larger for the samples with W and Mo buffers than those with Ta buffer. The sample with bcc-Mo buffer shows the highest robustness against annealing among the studied systems. We give a systematic picture based on the thermochemistry that can reasonably explain the observed buffer layer dependence of the variations in magnetic properties with annealing.

  6. Liquid crystal alignment in nanoporous anodic aluminum oxide layer for LCD panel applications.

    Science.gov (United States)

    Hong, Chitsung; Tang, Tsung-Ta; Hung, Chi-Yu; Pan, Ru-Pin; Fang, Weileun

    2010-07-16

    This paper reports the implementation and integration of a self-assembled nanoporous anodic aluminum oxide (np-AAO) film and liquid crystal (LC) on an ITO-glass substrate for liquid crystal display (LCD) panel applications. An np-AAO layer with a nanopore array acts as the vertical alignment layer to easily and uniformly align the LC molecules. Moreover, the np-AAO nanoalignment layer provides outstanding material properties, such as being inorganic with good transmittance, and colorless on ITO-glass substrates. In this application, an LCD panel, with the LC on the np-AAO nanoalignment layer, is successfully implemented on an ITO-glass substrate, and its performance is demonstrated. The measurements show that the LCD panel, consisting of an ITO-glass substrate and an np-AAO layer, has a transmittance of 60-80%. In addition, the LCD panel switches from a black state to a bright state at 3 V(rms), with a response time of 62.5 ms. In summary, this paper demonstrates the alignment of LC on an np-AAO layer for LCD applications.

  7. Growth of highly textured SnS on mica using an SnSe buffer layer

    International Nuclear Information System (INIS)

    Wang, S.F.; Fong, W.K.; Wang, W.; Surya, C.

    2014-01-01

    We report the growth of SnS thin films on mica substrates by molecular beam epitaxy. Excellent 2D layered structure and strong (001) texture were observed with a record low rocking curve full width at half maximum of ∼ 0.101° for the SnS(004) diffraction. An interface model is used to investigate the nucleation of SnS on mica which indicates the co-existence of six pairs of lateral growth orientations and is in excellent agreement with the experimental Φ-scan measurements indicating 12 peaks separated by 30° from each other. To control the lateral growth of the SnS epilayers we investigate the utilization of a thin SnSe buffer layer deposited on the mica substrate prior to the growth of the SnS thin film. The excellent lattice match between SnSe and mica enhances the alignment of the nucleation of SnS and suppresses the minor lateral orientations along the mica[110] direction and its orthogonal axis. Detailed low-frequency noise measurement was performed to characterize the trap density in the films and our results clearly demonstrate substantial reduction in the density of the localized states in the SnS epilayer with the use of an SnSe buffer layer. - Highlights: • A record low rocking curve FWHM for deposited SnS on mica • Investigation of the nucleation of SnS on mica using the interface model • Investigation of nucleation mechanism by phi-scan measurement • Grain boundary formation from crystallites of various nucleation orientations • Suppression of nucleation orientations using an SnSe buffer layer

  8. Directed Vertical Diffusion of Photovoltaic Active Layer Components into Porous ZnO-Based Cathode Buffer Layers.

    Science.gov (United States)

    Kang, Jia-Jhen; Yang, Tsung-Yu; Lan, Yi-Kang; Wu, Wei-Ru; Su, Chun-Jen; Weng, Shih-Chang; Yamada, Norifumi L; Su, An-Chung; Jeng, U-Ser

    2018-03-02

    Cathode buffer layers (CBLs) can effectively further the efficiency of polymer solar cells (PSCs), after optimization of the active layer. Hidden between the active layer and cathode of the inverted PSC device configuration is the critical yet often unattended vertical diffusion of the active layer components across CBL. Here, a novel methodology of contrast variation with neutron and anomalous X-ray reflectivity to map the multicomponent depth compositions of inverted PSCs, covering from the active layer surface down to the bottom of the ZnO-based CBL, is developed. Uniquely revealed for a high-performance model PSC are the often overlooked porosity distributions of the ZnO-based CBL and the differential diffusions of the polymer PTB7-Th and fullerene derivative PC 71 BM of the active layer into the CBL. Interface modification of the ZnO-based CBL with fullerene derivative PCBEOH for size-selective nanochannels can selectively improve the diffusion of PC 71 BM more than that of the polymer. The deeper penetration of PC 71 BM establishes a gradient distribution of fullerene derivatives over the ZnO/PCBE-OH CBL, resulting in markedly improved electron mobility and device efficiency of the inverted PSC. The result suggests a new CBL design concept of progressive matching of the conduction bands. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Microstructural characterization of chemical bath deposited and sputtered Zn(O,S) buffer layers

    International Nuclear Information System (INIS)

    Gautron, E.; Buffière, M.; Harel, S.; Assmann, L.; Arzel, L.; Brohan, L.; Kessler, J.; Barreau, N.

    2013-01-01

    The present work aims at investigating the microstructure of Zn(O,S) buffer layers relative to their deposition route, namely either chemical bath deposition (CBD) or RF co-sputtering process (PVD) under pure Ar. The core of the study consists of cross-sectional transmission electron microscopy (TEM) characterization of the differently grown Zn(O,S) thin films on co-evaporated Cu(In,Ga)Se 2 (CIGSe) absorbers. It shows that the morphology of Zn(O,S) layer deposited on CIGSe using CBD process is made of a thin layer of well oriented ZnS sphalerite-(111) and/or ZnS wurtzite-(0002) planes parallel to CIGSe chalcopyrite-(112) planes at the interface with CIGSe followed by misoriented nanometer-sized ZnS crystallites in an amorphous phase. As far as (PVD)Zn(O,S) is concerned, the TEM analyses reveal two different microstructures depending on the S-content in the films: for [S] / ([O] + [S]) = 0.6, the buffer layer is made of ZnO zincite and ZnS wurtzite crystallites grown nearly coherently to each other, with (0002) planes nearly parallel with CIGSe-(112) planes, while for [S] / ([O] + [S]) = 0.3, it is made of ZnO zincite type crystals with O atoms substituted by S atoms, with (0002) planes perfectly aligned with CIGSe-(112) planes. Such microstructural differences can explain why photovoltaic performances are dependent on the Zn(O,S) buffer layer deposition route. - Highlights: ► Zn(O,S) layers were grown by chemical bath (CBD) or physical vapor (PVD) deposition. ► For CBD, a 3 nm ZnS layer is followed by ZnS nano-crystallites in an amorphous phase. ► For PVD with [S] / ([O] + [S]) = 0.3, the layer has a Zn(O,S) zincite structure. ► For PVD with [S] / ([O] + [S]) = 0.6, ZnS wurtzite and ZnO zincite phases are mixed

  10. ZnO buffer layer for metal films on silicon substrates

    Science.gov (United States)

    Ihlefeld, Jon

    2014-09-16

    Dramatic improvements in metallization integrity and electroceramic thin film performance can be achieved by the use of the ZnO buffer layer to minimize interfacial energy between metallization and adhesion layers. In particular, the invention provides a substrate metallization method utilizing a ZnO adhesion layer that has a high work of adhesion, which in turn enables processing under thermal budgets typically reserved for more exotic ceramic, single-crystal, or metal foil substrates. Embodiments of the present invention can be used in a broad range of applications beyond ferroelectric capacitors, including microelectromechanical systems, micro-printed heaters and sensors, and electrochemical energy storage, where integrity of metallized silicon to high temperatures is necessary.

  11. High Performance Nano-Constituent Buffer Layer Thin Films to Enable Low Cost Integrated On-the-Move Communications Systems

    National Research Council Canada - National Science Library

    Cole, M. W; Nothwang, W. D; Hubbard, C; Ngo, E; Hirsch, S

    2004-01-01

    .... Utilizing a coplanar device design we successfully designed, fabricated, characterized, and optimized a high performance Ta2O5 thin film passive buffer layer on Si substrates, which will allow...

  12. Layered SnS sodium ion battery anodes synthesized near room temperature

    KAUST Repository

    Xia, Chuan

    2017-08-10

    In this report, we demonstrate a simple chemical bath deposition approach for the synthesis of layered SnS nanosheets (typically 6 nm or ~10 layers thick) at very low temperature (40 °C). We successfully synthesized SnS/C hybrid electrodes using a solution-based carbon precursor coating with subsequent carbonization strategy. Our data showed that the ultrathin carbon shell was critical to the cycling stability of the SnS electrodes. As a result, the as-prepared binder-free SnS/C electrodes showed excellent performance as sodium ion battery anodes. Specifically, the SnS/C anodes delivered a reversible capacity as high as 792 mAh·g−1 after 100 cycles at a current density of 100 mA·g−1. They also had superior rate capability (431 mAh·g−1 at 3,000 mA·g−1) and stable long-term cycling performance under a high current density (345 mAh·g−1 after 500 cycles at 3 A·g−1). Our approach opens up a new route to synthesize SnS-based hybrid materials at low temperatures for energy storage and other applications. Our process will be particularly useful for chalcogenide matrix materials that are sensitive to high temperatures during solution synthesis.

  13. Enhanced field emission from ZnO nanowire arrays utilizing MgO buffer between seed layer and silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Si [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Chen, Jiangtao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Mid. Road, Lanzhou 730000 (China); Liu, Jianlin [Quantum Structures Laboratory, Department of Electrical and Computer Engineering, University of California, Riverside, CA 92521 (United States); Qi, Jing, E-mail: qijing@lzu.edu.cn [The Key Laboratory for Magnetism and Magnetic Materials of MOE, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Wang, Yuhua, E-mail: wyh@lzu.edu.cn [Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2016-11-30

    Highlights: • We obtained ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer. • FE properties of ZnO nanowire arrays grown on ZnO seed layer on Si with MgO buffer is better than that without MgO buffer. • With MgO buffer, the ZnO seed layer shows lower top-bottom resistance and better electron transport. • The enhanced field emission properties can be attributed to good electron transport in seed layer, good nanowire alignment because of MgO buffer. - Abstract: Field emitters based on ZnO nanowires and other nanomaterials are promising high-brightness electron sources for field emission display, microscopy and other applications. The performance of a ZnO nanowire field emitter is linked to the quality, conductivity and alignment of the nanowires on a substrate, therefore requiring ways to improve these parameters. Here, ZnO nanowire arrays were grown on ZnO seed layer on silicon substrate with MgO buffer between the seed layer and Si. The turn-on field and enhancement factor of these nanowire arrays are 3.79 V/μm and 3754, respectively. These properties are improved greatly compared to those of ZnO nanowire arrays grown on ZnO seed layer without MgO buffer, which are 5.06 V/μm and 1697, respectively. The enhanced field emission properties can be attributed to better electron transport in seed layer, and better nanowire alignment because of MgO buffer.

  14. Bimetallic nanocomposite as hole transport co-buffer layer in organic solar cell

    Science.gov (United States)

    Mola, Genene Tessema; Arbab, Elhadi A. A.

    2017-12-01

    Silver-zinc bimetallic nanocomposite (Ag:Zn BiM-NPs) was used as an inter-facial buffer layer in the preparation of thin film organic solar cell (TFOSC). The current investigation focuses on the effect of bimetallic nanoparticles on the performance of TFOSC. A number experiments were conducted by employing Ag:Zn nanocomposite buffer layer of thickness 1 nm at various positions of the device structure. In all cases, we found significant improvement on the power conversion efficiency of the solar cells. It is also noted that the open circuit voltage of the devices are decreasing when Ag:Zn form direct contact with the ITO electrode and without the inclusion of PEDOT:PSS. However, all results show that the introduction of Ag:Zn nanocomposite layer close to PEDOT:PSS could be beneficial to improve the charge transport processes in the preparation of thin film organic solar cell. The Ag:Zn BiM-NPs and the device properties were presented and discussed in terms of optical, electrical and film morphologies of the devices.

  15. High-resolution electron microscopy study of Ni81Fe19 film with Co33Cr67 buffer layer

    International Nuclear Information System (INIS)

    Xu, Q.Y.; Wang, Z.M.; Shen, F.; Du, Y.W.; Zhang, Z.

    2003-01-01

    The anisotropic magnetoresistance (AMR) in permalloy Ni 81 Fe 19 film deposited on a 1.2 nm Co 33 Cr 67 buffer layer was significantly enhanced. The high-resolution electron microscopy was used to study the microstructure of Ni 81 Fe 19 film with and without Co 33 Cr 67 buffer layer. It was found that Co 33 Cr 67 buffer layer can induce good (1 1 1) texture, while without Co 33 Cr 67 buffer layer, Ni 81 Fe 19 film show randomly oriented grain structure. The Δρ/ρ enhancement is attributed to the decrease in the resistivity ρ of the Ni 81 Fe 19 film due to the formation of the large (1 1 1) textured grains in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer. However, the surface roughness of substrate may limit the (1 1 1) textured grain size and induce additional grain boundaries in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer, limit the enhancement of the AMR effect

  16. Porous anodic alumina on galvanically grown PtSi layer for application in template-assisted Si nanowire growth

    Directory of Open Access Journals (Sweden)

    Stavrinidou Eleni

    2011-01-01

    Full Text Available Abstract We report on the fabrication and morphology/structural characterization of a porous anodic alumina (PAA/PtSi nano-template for use as matrix in template-assisted Si nanowire growth on a Si substrate. The PtSi layer was formed by electroless deposition from an aqueous solution containing the metal salt and HF, while the PAA membrane by anodizing an Al film deposited on the PtSi layer. The morphology and structure of the PtSi layer and of the alumina membrane on top were studied by Scanning and High Resolution Transmission Electron Microscopies (SEM, HRTEM. Cross sectional HRTEM images combined with electron diffraction (ED were used to characterize the different interfaces between Si, PtSi and porous anodic alumina.

  17. Morphology control of anodic ZrO2 layer for the prevention of H2 production from Zr-4 cladding

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y. J.; Park, J. W.; Cho, S. O. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    Since the Fukushima disaster happened, studies on accident-resistant nuclear fuel has been carried out actively. There has been an attempt to protect zircaloy fuel cladding by coating SiC. Research on producing oxide layer that can block fuel cladding from water on the surface of zircaloy fuel cladding by means of anodizing to reduce the rate of oxidation of fuel cladding at Loss Of Coolant Accident (LOCA) is an significant ongoing study subject. Applying nanostructured oxide layer to the prevention of thermal deformation of oxide layer was already suggested in our research group, the reasons of which is nanoporous structure is better than nanotube structure in terms of corrosion-resistant structure because nanotube structure can be easily peeled off. In this study, methods which are able to control morphology between nanoporous and nanotube structure were conducted by changing the anodizing conditions. Hence, Using glycerol and ammonium fluoride, Zircaloy-4 was anodized by varying water contents and applied voltage. It reveals that the alloy transition from nanoporous structure to nanotube structure can be changed by varying water contents of anodizing solution and applied voltage. Anodizing conditions determining nanoporous structure were obtained. According to the mechanism already suggested, nanoporous oxide layer that can seal the fuel cladding perfectly, and increase critical heat flux (CHF) due to large surface area is easily produced. This results obtained in this paper expected to be facilitated fabrication of accident-resistant nuclear fuel cladding.

  18. Hydrogen responses of ultrathin Pd films and nanowire networks with a Ti buffer layer.

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, X. Q.; Wang, Y. L.; Xiao, Z. L.; Latimer, M. L.; Xu, T.; Kwok, W. K. (Materials Science Division); (Northern Illinois Univ.)

    2012-01-01

    We report on hydrogen responses of ultrathin films and nanowire networks of palladium on titanium buffered silicon substrates and filtration membranes, respectively. We found that in both systems signatures such as retarding responses and saturation of the resistance changes at high hydrogen concentrations associated with the transition from Pd/H solid solution to Pd hydride diminish with decreasing the thickness of the palladium layer from 7 to 2 nm. Our results not only reveal a new way to suppress the phase transition in Pd/H system but also provide an alternative approach to achieve fast and sensitive hydrogen sensors with a wide concentration detection range.

  19. Strontium Titanate Buffer Layers on Cu/33%Ni Substrates using a Novel Solution Chemistry

    DEFF Research Database (Denmark)

    Pallewatta, Pallewatta G A P; Yue, Zhao; Hui, Tian

    2013-01-01

    SrTiO3 is a widely studied perovskite material due to its advantages as a buffer template which can be simply applied between a metal substrate tape and a superconducting layer in 2G high temperature superconducting (HTS) tapes. In this study, heteroepitaxial SrTiO3 thin films were deposited...... on textured Cu/33%Ni substrates using dip-coating in a precursor solution followed by drying and annealing under controlled oxygen partial pressures. The control of the ambient atmosphere during annealing is an important experimental issue in order to achieve thin films with high quality surface texture. We...

  20. Two-Dimensional SnO Anodes with a Tunable Number of Atomic Layers for Sodium Ion Batteries

    KAUST Repository

    Zhang, Fan

    2017-01-18

    We have systematically changed the number of atomic layers stacked in 2D SnO nanosheet anodes and studied their sodium ion battery (SIB) performance. The results indicate that as the number of atomic SnO layers in a sheet decreases, both the capacity and cycling stability of the Na ion battery improve. The thinnest SnO nanosheet anodes (two to six SnO monolayers) exhibited the best performance. Specifically, an initial discharge and charge capacity of 1072 and 848 mAh g-1 were observed, respectively, at 0.1 A g-1. In addition, an impressive reversible capacity of 665 mAh g-1 after 100 cycles at 0.1 A g-1 and 452 mAh g-1 after 1000 cycles at a high current density of 1.0 A g-1 was observed, with excellent rate performance. As the average number of atomic layers in the anode sheets increased, the battery performance degraded significantly. For example, for the anode sheets with 10-20 atomic layers, only a reversible capacity of 389 mAh g-1 could be obtained after 100 cycles at 0.1 A g-1. Density functional theory calculations coupled with experimental results were used to elucidate the sodiation mechanism of the SnO nanosheets. This systematic study of monolayer-dependent physical and electrochemical properties of 2D anodes shows a promising pathway to engineering and mitigating volume changes in 2D anode materials for sodium ion batteries. It also demonstrates that ultrathin SnO nanosheets are promising SIB anode materials with high specific capacity, stable cyclability, and excellent rate performance.

  1. Effects of the insertion of a thick sp2 buffer layer on the adhesion of cBN-rich film

    International Nuclear Information System (INIS)

    Wong, S.F.; Ong, C.W.; Pang, G.K.H.; Baba-Kishi, K.Z.; Lau, W.M.

    2004-01-01

    A method was proposed and examined to deposit thick cubic boron nitride (cBN)-rich layer of good adhesion to silicon substrate. The method combined (i) the insertion of a thick sp 2 buffer layer, and (ii) the use of an appropriate assist ion beam energy for the growth of the cBN-rich top layer. The sp 2 -bonded boron nitride buffer layer was deposited under irradiation of ions with energies in the range of 200-360 eV. The buffer layer was found to contain curled graphitic basal planes, and so was supposed to be relatively deformable, and facilitate the relaxation of stresses in the cBN-rich top layer. The ion assist introduced during the growth of the cBN-rich layer was supposed to both create and annihilate defects, and so resulted in the generation and relaxation of internal stresses. Results showed that the insertion of a 492 nm sp 2 buffer layer, and the use of a beam energy of 450 eV for assisting the growth of the top layer can produce a 643-nm-thick cBN-rich top layer with satisfactory adhesion, a high cBN content of 87 vol %, a hardness of 57 GPa, and an elastic modulus of 612 GPa

  2. A Novel Method for Fabricating Double Layers Porous Anodic Alumina in Phosphoric/Oxalic Acid Solution and Oxalic Acid Solution

    Directory of Open Access Journals (Sweden)

    Yanfang Xu

    2016-01-01

    Full Text Available A novel method for fabricating ordered double layers porous anodic alumina (DL-PAA with controllable nanopore size was presented. Highly ordered large pore layer with interpore distance of 480 nm was fabricated in phosphoric acid solution with oxalic acid addition at the potential of 195 V and the small pore layer was fabricated in oxalic acid solution at the potential from 60 to 100 V. Experimental results show that the thickness of large pore layer is linearly correlative with anodizing time, and pore diameter is linearly correlative with pore widening time. When the anodizing potential in oxalic acid solution was adjusted from 60 to 100 V, the small pore layers with continuously tunable interpore distance from 142 to 241 nm and pore density from 1.94×109 to 4.89×109 cm−2 were obtained. And the interpore distance and the pore density of small pore layers are closely correlative with the anodizing potential. The fabricated DL-PAA templates can be widely utilized for fabrication of ordered nanomaterials, such as superhydrophobic or gecko-inspired adhesive materials and metal or semiconductor nanowires.

  3. Threading Dislocations in InGaAs/GaAs (001) Buffer Layers for Metamorphic High Electron Mobility Transistors

    Science.gov (United States)

    Song, Yifei; Kujofsa, Tedi; Ayers, John E.

    2018-03-01

    In order to evaluate various buffer layers for metamorphic devices, threading dislocation densities have been calculated for uniform composition In x Ga1-x As device layers deposited on GaAs (001) substrates with an intermediate graded buffer layer using the L MD model, where L MD is the average length of misfit dislocations. On this basis, we compare the relative effectiveness of buffer layers with linear, exponential, and S-graded compositional profiles. In the case of a 2 μm thick buffer layer linear grading results in higher threading dislocation densities in the device layer compared to either exponential or S-grading. When exponential grading is used, lower threading dislocation densities are obtained with a smaller length constant. In the S-graded case, lower threading dislocation densities result when a smaller standard deviation parameter is used. As the buffer layer thickness is decreased from 2 μm to 0.1 μm all of the above effects are diminished, and the absolute threading dislocation densities increase.

  4. Plasmonic organic photovoltaic devices with graphene based buffer layers for stability and efficiency enhancement

    Science.gov (United States)

    Stratakis, Emmanuel; Stylianakis, Minas M.; Koudoumas, Emmanuel; Kymakis, Emmanuel

    2013-05-01

    Enhancement of photoconversion efficiency (PCE) and stability in bulk heterojunction (BHJ) plasmonic organic photovoltaic devices (OPVs) incorporating graphene oxide (GO) thin films as the hole transport layer (HTL) and surfactant free Au nanoparticles (NPs) between the GO HTL and the photoactive layers is demonstrated. In particular the plasmonic GO-based devices exhibited a performance enhancement by 30% compared to the devices using the traditional PEDOT:PSS layer. Likewise, they preserved 50% of their initial PCE after 45 h of continuous illumination, contrary to the PEDOT:PSS-based ones that die after 20 h. The performance increase is attributed to the improved photocurrent and fill factor owing to the enhanced exciton generation rate due to NP-induced plasmon absorption enhancement. Besides this, the stability enhancement can be attributed to limited oxygen and/or indium diffusion from the indium tin oxide (ITO) electrode into the active layer. The industrial exploitation of composite GO/NPs as efficient buffer layers in OPVs is envisaged.

  5. Epitaxial Growth of Cadmium Selenide Films on Silicon with a Silicon Carbide Buffer Layer

    Science.gov (United States)

    Antipov, V. V.; Kukushkin, S. A.; Osipov, A. V.; Rubets, V. P.

    2018-03-01

    An epitaxial cubic 350-nm-thick cadmium selenide has been grown on silicon for the first time by the method of evaporation and condensation in a quasi-closed volume. It is revealed that, in this method, the optimum substrate temperature is 590°C, the evaporator temperature is 660°C, and the growth time is 2 s. To avoid silicon etching by selenium with formation of amorphous SiSe2, a high-quality 100-nm-thick buffer silicon carbide layer has been synthesized on the silicon surface by substituting atoms. The powder diffraction pattern and the Raman spectrum unambiguously correspond to cubic cadmium selenide crystal. The ellipsometric, Raman, and electron diffraction analyses demonstrate high structural perfection of the cadmium selenide layer and the absence of a polycrystalline phase.

  6. Improvement of InN layers deposited on Si(111) by RF sputtering using a low-growth-rate InN buffer layer

    International Nuclear Information System (INIS)

    Valdueza-Felip, S.; Ibáñez, J.; Monroy, E.; González-Herráez, M.; Artús, L.; Naranjo, F.B.

    2012-01-01

    We investigate the influence of a low-growth-rate InN buffer layer on structural and optical properties of wurtzite nanocrystalline InN films deposited on Si(111) substrates by reactive radio-frequency sputtering. The deposition conditions of the InN buffer layer were optimized in terms of morphological and structural quality, leading to films with surface root-mean-square roughness of ∼ 1 nm under low-growth-rate conditions (60 nm/h). The use of the developed InN buffer layer improves the crystalline quality of the subsequent InN thick films deposited at high growth rate (180 nm/h), as confirmed by the narrowing of X-ray diffraction peaks and the increase of the average grain size of the layers. This improvement of the structural quality is further confirmed by Raman scattering spectroscopy measurements. Room temperature PL emission peaking at ∼ 1.58 eV is observed for InN samples grown with the developed buffer layer. The crystal and optical quality obtained for InN films grown on Si(111) using the low-growth-rate InN buffer layer become comparable to high-quality InN films deposited directly on GaN templates by RF sputtering. - Highlights: ► Improved RF-sputtered InN films on Si(111) using a low-growth-rate InN buffer layer. ► Enhanced structural quality confirmed by X-ray diffraction and Raman measurements. ► Room-temperature photoluminescence emission at 1.58 eV. ► InN films deposited with buffer layer on Si comparable to InN LAYERS on GaN templates.

  7. Study on calcination of bi-layered films produced by anodizing iron in dimethyl sulfoxide electrolyte

    International Nuclear Information System (INIS)

    Jagminas, Arūnas; Klimas, Vaclovas; Mažeika, Kęstutis; Mickevičius, Sigitas; Balakauskas, Saulius

    2012-01-01

    Research on well adherent, thick and nanoporous oxide film formation onto the metal substrates underwent a major burst throughout the last decade. In the current study, thick bi-layered films produced onto a pure iron surface by anodizing way in dimethyl sulfoxide (DMSO) electrolyte containing silica hexafluoride acid have been investigated upon the annealing in air. Compositional, phase and structural transformations of the film material to hematite, α-Fe 2 O 3 , were studied using Mössbauer spectroscopy at room to cryogenic temperatures, thermogravimetry (TG), differential thermal analysis (DTA), photoemission spectroscopy, scanning electron microscopy (SEM), and wave dispersive X-ray spectroscopy (WDX). Experimental findings indicated that much longer heating in air is required for these films to be fully transformed to hematite. This effect is linked here with the complex nature of DMSO films. Based on the combined WDX, photoemission and Mössbauer spectroscopy results, the transformations taken place during calcination of such amorphous films by heat-treatment in air to crystalline hematite have been determined. Investigations on the calcination effects of thick iron anodic films reported here offer opportunities for both fundamental research and practical applications.

  8. Preparation of electron buffer layer with crystalline ZnO nanoparticles in inverted organic photovoltaic cells

    Science.gov (United States)

    Lee, Donghwan; Kang, Taeho; Choi, Yoon-Young; Oh, Seong-Geun

    2017-06-01

    Zinc oxide (ZnO) nanoparticles synthesized through sol-gel method were used to fabricate the electron buffer layer in inverted organic photovoltaic cells (OPVs) after thermal treatment. To investigate the effect of thermal treatment on the formation of crystalline ZnO nanoparticles, the amorphous ZnO nanoparticles were treated via hydrothermal method. The crystalline phase of ZnO with well-ordered structure could be obtained when the amorphous phase of ZnO was processed under hydrothermal treatment at 170 °C. The crystalline structure of ZnO thin film in inverted organic solar cell could be obtained under relatively low annealing temperature by using thermally treated ZnO nanoparticles. The OPVs fabricated by using crystalline ZnO nanoparticles for electron buffer layer exhibited higher efficiency than the conventional ZnO nanoparticles. The best power conversion efficiency (PCE) was achieved for 7.16% through the ZnO film using the crystalline ZnO nanoparticles. The proposed method to prepared ZnO nanoparticles (NPs) could effectively reduce energy consumption during the fabrication of OPVs, which would greatly contribute to advantages such as lower manufacturing costs, higher productivity and application on flexible substrates.

  9. Copper variation in Cu(In,Ga)Se{sub 2} solar cells with indium sulphide buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Spiering, S., E-mail: stefanie.spiering@zsw-bw.de [Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW) Baden-Wuerttemberg, Industriestrasse 6, 70565 Stuttgart (Germany); Paetel, S.; Kessler, F. [Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW) Baden-Wuerttemberg, Industriestrasse 6, 70565 Stuttgart (Germany); Igalson, M.; Abdel Maksoud, H. [Warsaw University of Technology (WUT), Faculty of Physics, Koszykowa 75, 00-662 Warszawa (Poland)

    2015-05-01

    In the manufacturing of Cu(In,Ga)Se{sub 2} (CIGS) thin film solar cells the application of a buffer layer on top of the absorber is essential to obtain high efficiency devices. Regarding the roll-to-roll production of CIGS cells and modules a vacuum deposition process for the buffer is preferable to the conventional cadmium sulphide buffer deposited in a chemical bath. Promising results have already been achieved for the deposition of indium sulphide buffer by different vacuum techniques. The solar device performance is very sensitive to the conditions at the absorber-buffer heterojunction. In view of optimization we investigated the influence of the Cu content in the absorber on the current-voltage characteristics. In this work the integral copper content was varied between 19 and 23 at.% in CIGS on glass substrates. An improvement of the cell performance by enhanced open circuit voltage was observed for a reduction to ~ 21 at.% when thermally evaporated indium sulphide was applied as the buffer layer. The influence of stoichiometry deviations on the transport mechanism and secondary barriers in the device was studied using detailed dark and light current-voltage analysis and admittance spectroscopy and compared to the reference CdS-buffered cells. We conclude that the composition of the absorber in the interface region affects current transport in In{sub x}S{sub y}-buffered and CdS-buffered cells in different ways hence optimal Cu content in those two types of devices is different. - Highlights: • Influence of Cu-variation in CIGS cells with In{sub x}S{sub y} buffer layer on cell performance • Enhanced efficiency by slight reduction of Cu-content to 21 at.% • Contribution of tunnelling-enhanced interface recombination for higher Cu-content.

  10. New superjuction LDMOS with surface and bulk electric field modulation by buffered step doping and multi floating buried layers

    Science.gov (United States)

    Cao, Zhen; Duan, Baoxing; Yuan, Song; Shi, Tongtong; Yang, Yintang

    2017-11-01

    A new superjunction lateral double diffused MOSFET with surface and bulk electric field modulation (SBEFM SJ-LDMOS) by applying of multiple floating buried layers and buffered step doping is proposed in this paper. The Multiple N-type floating buried layers are embedded in P-substrate, to reduce the amount of field crowding at N+/N-buffer/P-substrate junction by spreading the vertical depletion layer, which effectively improves the bulk electric field distribution in SJ-LDMOS, and the N+/N-buffer/P-substrate junction and the auxiliary MFB layers/substrate junctions jointly sustain a high vertical breakdown voltage (BV). In addition, based on the buffered step doping layer under the SJ layer, a uniform lateral electric field at the drift region surface of the device is obtained. Therefore, the bulk and surface electric field are both optimized simultaneously in SBEFM SJ-LDMOS. Simulated results show that compared with the conventional Buffered SJ-LDMOS and BSD SJ-LDMOS, the proposed SBEFM SJ-LDMOS improves BV by 131.7% and 80.4%, respectively, at the same drift region length and with low specific ON-resistance (RON,sp). SBEFM SJ-LDMOS exhibits excellent performance with the power figure-of-merit (FOM=BV2/RON,sp) of 13.07 MW/cm2.

  11. Enhancing the platinum atomic layer deposition infiltration depth inside anodic alumina nanoporous membrane

    Energy Technology Data Exchange (ETDEWEB)

    Vaish, Amit, E-mail: anv@udel.edu; Krueger, Susan; Dimitriou, Michael; Majkrzak, Charles [National Institute of Standards and Technology (NIST) Center for Neutron Research, Gaithersburg, MD 20899-8313 (United States); Vanderah, David J. [Institute for Bioscience and Biotechnology Research, NIST, Rockville, Maryland 20850 (United States); Chen, Lei, E-mail: lei.chen@nist.gov [NIST Center for Nanoscale Science and Technology, Gaithersburg, Maryland 20899-8313 (United States); Gawrisch, Klaus [Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892 (United States)

    2015-01-15

    Nanoporous platinum membranes can be straightforwardly fabricated by forming a Pt coating inside the nanopores of anodic alumina membranes (AAO) using atomic layer deposition (ALD). However, the high-aspect-ratio of AAO makes Pt ALD very challenging. By tuning the process deposition temperature and precursor exposure time, enhanced infiltration depth along with conformal coating was achieved for Pt ALD inside the AAO templates. Cross-sectional scanning electron microscopy/energy dispersive x-ray spectroscopy and small angle neutron scattering were employed to analyze the Pt coverage and thickness inside the AAO nanopores. Additionally, one application of platinum-coated membrane was demonstrated by creating a high-density protein-functionalized interface.

  12. P-6 : Impact of buffer layers on the self-aligned top-gate a-IGZO TFT characteristics

    NARCIS (Netherlands)

    Nag, M.; en de rest

    2015-01-01

    In this work we present the impact of buffer layers deposited by various techniques such as plasma enhanced chemical deposition (PECVD), physical vapor deposition (PVD) and atomic layer deposition (ALD) techniques on self-aligned (SA) top gate amorphous-Indium-Gallium-Zinc-Oxide (a-IGZO) TFT

  13. ALD Buffer Layer Growth and Interface Formation on Cu(In,Ga)Se2 Solar Cell Absorbers

    OpenAIRE

    Sterner, Jan

    2004-01-01

    Cu(In,Ga)Se2 (CIGS) thin film solar cells contain a thin layer of CdS. To avoid toxic heavy-metal-containing waste in the module production the development of a cadmium-free buffer layer is desirable. This thesis considers alternative Cd-free buffer materials deposited by Atomic Layer Deposition (ALD). Conditions of the CIGS surface necessary for ALD growth are investigated and the heterojunction interface is characterized by band alignment studies of ZnO/CIGS and In2S3/CIGS interfaces. The t...

  14. Measuring the thermal conductivity of the GaN buffer layer in AlGaN/GaN HEMTs

    OpenAIRE

    Power, Maire; Pomeroy, James W; Otoki, Yohei; Tanaka, Takeshi; Wada, Jiro; Kuzuhara, Masaaki; Jantz, Wolfgang; Souzis, Andrew; Kuball, Martin H H

    2015-01-01

    The thermal conductivity of the GaN buffer layer in AlGaN/GaN devices can be determined by measuring the vertical temperature gradient through this layer. In this work, diamond micro-thermometers and standard micro-Raman thermography were used to determine the surface and volumetric depth average temperature, respectively, of the carbon-doped GaN buffer layer in AlGaN/GaN transistors. By comparing measured temperatures with finite element thermal simulation, a thermal conductivity of 200 ± 20...

  15. Ultra-smooth epitaxial Ge grown on Si(001) utilizing a thin C-doped Ge buffer layer

    KAUST Repository

    Mantey, J.

    2013-01-01

    Here, we present work on epitaxial Ge films grown on a thin buffer layer of C doped Ge (Ge:C). The growth rate of Ge:C is found to slow over time and is thus unsuitable for thick (>20 nm) layers. We demonstrate Ge films from 10 nm to >150 nm are possible by growing pure Ge on a thin Ge:C buffer. It is shown that this stack yields exceedingly low roughness levels (comparable to bulk Si wafers) and contains fewer defects and higher Hall mobility compared to traditional heteroepitaxial Ge. The addition of C at the interface helps reduce strain by its smaller atomic radius and its ability to pin defects within the thin buffer layer that do not thread to the top Ge layer. © 2013 AIP Publishing LLC.

  16. Layer-Tunable Phosphorene Modulated by the Cation Insertion Rate as a Sodium-Storage Anode.

    Science.gov (United States)

    Huang, Zhaodong; Hou, Hongshuai; Zhang, Yan; Wang, Chao; Qiu, Xiaoqing; Ji, Xiaobo

    2017-09-01

    Liquid phase exfoliation of few-layer phosphorene (FL-P) is extensively explored in recent years. Nevertheless, their deficiencies such as ultralong sonication time, limited flake size distribution, and uncontrollable thicknesses are major hurdles for the development of phosphorene-based materials. Herein, electrochemical cationic intercalation has been introduced to prepare phosphorene, through which large-area FL-P without surface functional groups can be efficiently attained (less than 1 h). More importantly, its layer number (from 2 to 11 layers) can be manipulated by changing the applied potential. The as-obtained phosphorene delivers superior sodium-storage performances when directly utilized as an anode material in sodium-ion batteries. This electrochemical cation insertion method to prepare phosphorene should greatly facilitate the development of phosphorene-based technologies. Moreover, this work provides the possibility for the scalable preparation of monolayer 2D materials by exploring intercalation ions. Additionally, the successful electrochemical exfoliation of phosphorene can promote the application of electrochemical exfoliation in other 2D materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Co-extrusion of electrolyte/anode functional layer/anode triple-layer ceramic hollow fibres for micro-tubular solid oxide fuel cells-electrochemical performance study

    Science.gov (United States)

    Li, Tao; Wu, Zhentao; Li, K.

    2015-01-01

    In this study, the effects of an anode functional layer (AFL) with controlled thickness on physical and electrochemical properties of a micro-tubular SOFC have been systematically studied. A series of electrolyte/AFL/anode triple-layer hollow fibres with controllable AFL thicknesses (16.9-52.7 μm) have been fabricated via a single-step phase-inversion assisted co-extrusion technique. Both robustness of the cell and gas-tightness of the electrolyte layer are considerably improved by introducing the AFL of this type. The fracture force of the sample with the thickest AFL (9.67 N) almost doubles when compared to the electrolyte/anode dual-layer counterpart (5.24 N). Gas-tightness of the electrolyte layer is also considerably increased as AFL contributes to better-matched sintering behaviours between different components. Moreover, the formation of an AFL simultaneously with electrolyte and anode significantly improves the cell performances. The sample with the thinnest AFL (approximately 16.9 μm, 6% of the total anode thickness) leads to a 30% (from 0.89 to 1.21 W cm-2) increase in maximum power density, due to increased triple-phase boundaries (TPB). However, further increase in TPB from a thicker AFL is less effective for improving the cell performance, due to the substantially increased fuel diffusion resistance and subsequently higher concentration polarization. This indicates that the control over the AFL thickness is critically important in avoiding offsetting the benefits of extended TPB and consequently decreased cell performances.

  18. Carbon thin films deposited by the magnetron sputtering technique using cobalt, copper and nickel as buffer-layers; Filmes finos de carbono depositados por meio da tecnica de magnetron sputtering usando cobalto, cobre e niquel como buffer-layers

    Energy Technology Data Exchange (ETDEWEB)

    Costa e Silva, Danilo Lopes

    2015-11-01

    In this work, carbon thin films were produced by the magnetron sputtering technique using single crystal substrates of alumina c-plane (0001) and Si (111) and Si (100) substrates, employing Co, Ni and Cu as intermediate films (buffer-layers). The depositions were conducted in three stages, first with cobalt buffer-layers where only after the production of a large number of samples, the depositions using cooper buffer-layers were carried out on Si substrates. Then, depositions were performed with nickel buffer layers using single-crystal alumina substrates. The crystallinity of the carbon films was evaluated by using the technique of Raman spectroscopy and, then, by X-ray diffraction (XRD). The morphological characterization of the films was performed by scanning electron microscopy (SEM and FEG-SEM) and high-resolution transmission electron microscopy (HRTEM). The XRD peaks related to the carbon films were observed only in the results of the samples with cobalt and nickel buffer-layers. The Raman spectroscopy showed that the carbon films with the best degree of crystallinity were the ones produced with Si (111) substrates, for the Cu buffers, and sapphire substrates for the Ni and Co buffers, where the latter resulted in a sample with the best crystallinity of all the ones produced in this work. It was observed that the cobalt has low recovering over the alumina substrates when compared to the nickel. Sorption tests of Ce ions by the carbon films were conducted in two samples and it was observed that the sorption did not occur probably because of the low crystallinity of the carbon films in both samples. (author)

  19. Theoretical simulation of performances in CIGS thin-film solar cells with cadmium-free buffer layer

    Science.gov (United States)

    Luo, Kang; Sun, Yulin; Zhou, Liyu; Wang, Fang; Wu, Fang

    2017-08-01

    Copper indium gallium selenium (CIGS) thin film solar cells have become one of the hottest topics in solar energy due to their high photoelectric transformation efficiency. To real applications, CIGS thin film is covered by the buffer layer and absorption layer. Traditionally, cadmium sulfide (CdS) is inserted into the middle of the window layer (ZnO) and absorption layer (CIGS) as a buffer layer. However, the application of the GIGS/CdS thin film solar cells has been limited because of the environmental pollution resulting from the toxic cadmium atom. Although zinc sulfide (ZnS) has been proposed to be one of the candidates, the performance of such battery cells has not been investigated. Here, in this paper, we systematically study the possibility of using zinc sulfide (ZnS) as a buffer layer. By including the effects of thickness, concentration of a buffer layer, intrinsic layer and the absorbing layer, we find that photoelectric transformation efficiency of ZnO/ZnS(n)/CIGS(i)/CIGS(p) solar cell is about 17.22%, which is qualified as a commercial solar cell. Moreover, we also find that the open-circuit voltage is ∼0.60 V, the short-circuit current is ∼36.99 mA/cm2 and the filled factor is ∼77.44%. Therefore, our results suggest that zinc sulfide may be the potential candidate of CdS as a buffer layer. Project supported by the NSF of Jiangsu Province (No. BK20131420), the Postgraduate Innovation Project of Jiangsu Province (No. KYLX15_0926), and the NJFU Outstanding Young Scholars Funding.

  20. Effect of Coating Parameters of the Buffer Layer on the Shape Ratio of TRISO-Coated Particles

    International Nuclear Information System (INIS)

    KIm, Weon Ju; Park, Jong Hoon; Park, Ji Yeon; Lee, Young Woo; Chang, Jong Hwa

    2005-01-01

    Fuel for high temperature gas-cooled reactors (HTGR's) consists of TRISO-coated particles. Fluidized bed chemical vapor deposition (FBCVD) has been applied to fabricate the TRISO-coated fuel particles. The TRISO particles consist of UO 2 microspheres coated with layers of porous pyrolytic carbon (PyC), inner dense PyC (IPyC), SiC, and outer dense PyC (OPyC). The porous PyC coating layer, called the buffer layer, attenuates fission recoils and provides void volume for gaseous fission products and carbon monoxide. The buffer layer, which has the highest coating rate among the coating layers, shows the largest variation of the coating thickness within a particle and a batch. This could be the most plausible source of an asphericity in the TRISO particles. The aspherical particles are expected to have an inferior fuel performance. Miller et al. have predicted that a larger stress is developed within the coating layers and thus the failure probability increases in the particles with high aspect ratios. Therefore, the shape of the TRISO-coated particles should be controlled properly and has been one of the important inspection items for the quality control of the fabrication process. In this paper, we investigated the effect of coating parameters of the buffer layer on the shape of the TRISO particles. The flow rate of coating gas and the coating temperature were varied to control the buffer layer. The asphericity of the TRISO-coated particles was evaluated for the various coating conditions of the buffer layer, but at constant coating parameters for the IPyC/SiC/OPyC layers

  1. Atmospheric spatial atomic layer deposition of Zn(O,S) buffer layer for Cu(In,Ga)Se2 solar cells

    NARCIS (Netherlands)

    Frijters, C.H.; Poodt, P.; Illeberi, A.

    2016-01-01

    Zinc oxysulfide has been grown by spatial atomic layer deposition (S-ALD) and successfully applied as buffer layer in Cu(In, Ga)Se2 (CIGS) solar cells. S-ALD combines high deposition rates (up to nm/s) with the advantages of conventional ALD, i.e. excellent control of film composition and superior

  2. Carbon thin films deposited by the magnetron sputtering technique using cobalt, copper and nickel as buffer-layers

    International Nuclear Information System (INIS)

    Costa e Silva, Danilo Lopes

    2015-01-01

    In this work, carbon thin films were produced by the magnetron sputtering technique using single crystal substrates of alumina c-plane (0001) and Si (111) and Si (100) substrates, employing Co, Ni and Cu as intermediate films (buffer-layers). The depositions were conducted in three stages, first with cobalt buffer-layers where only after the production of a large number of samples, the depositions using cooper buffer-layers were carried out on Si substrates. Then, depositions were performed with nickel buffer layers using single-crystal alumina substrates. The crystallinity of the carbon films was evaluated by using the technique of Raman spectroscopy and, then, by X-ray diffraction (XRD). The morphological characterization of the films was performed by scanning electron microscopy (SEM and FEG-SEM) and high-resolution transmission electron microscopy (HRTEM). The XRD peaks related to the carbon films were observed only in the results of the samples with cobalt and nickel buffer-layers. The Raman spectroscopy showed that the carbon films with the best degree of crystallinity were the ones produced with Si (111) substrates, for the Cu buffers, and sapphire substrates for the Ni and Co buffers, where the latter resulted in a sample with the best crystallinity of all the ones produced in this work. It was observed that the cobalt has low recovering over the alumina substrates when compared to the nickel. Sorption tests of Ce ions by the carbon films were conducted in two samples and it was observed that the sorption did not occur probably because of the low crystallinity of the carbon films in both samples. (author)

  3. Fabrication of super slippery sheet-layered and porous anodic aluminium oxide surfaces and its anticorrosion property

    Science.gov (United States)

    Song, Tingting; Liu, Qi; Liu, Jingyuan; Yang, Wanlu; Chen, Rongrong; Jing, Xiaoyan; Takahashi, Kazunobu; Wang, Jun

    2015-11-01

    Inspired by natural plants such as Nepenthes pitcher plants, super slippery surfaces have been developed to improve the attributes of repellent surfaces. In this report, super slippery porous anodic aluminium oxide (AAO) surfaces have fabricated by a simple and reproducible method. Firstly, the aluminium substrates were treated by an anodic process producing micro-nano structured sheet-layered pores, and then immersed in Methyl Silicone Oil, Fluororalkylsilane (FAS) and DuPont Krytox, respectively, generating super slippery surfaces. Such a good material with excellent anti-corrosion property through a simple and repeatable method may be potential candidates for metallic application in anti-corrosion and extreme environment.

  4. Effect of Alloy 625 Buffer Layer on Hardfacing of Modified 9Cr-1Mo Steel Using Nickel Base Hardfacing Alloy

    Science.gov (United States)

    Chakraborty, Gopa; Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murugesan, S.; Dasgupta, Arup

    2016-04-01

    Dashpot piston, made up of modified 9Cr-1Mo steel, is a part of diverse safety rod used for safe shutdown of a nuclear reactor. This component was hardfaced using nickel base AWS ER NiCr-B alloy and extensive cracking was experienced during direct deposition of this alloy on dashpot piston. Cracking reduced considerably and the component was successfully hardfaced by application of Inconel 625 as buffer layer prior to hardface deposition. Hence, a separate study was undertaken to investigate the role of buffer layer in reducing the cracking and on the microstructure of the hardfaced deposit. Results indicate that in the direct deposition of hardfacing alloy on modified 9Cr-1Mo steel, both heat-affected zone (HAZ) formed and the deposit layer are hard making the thickness of the hard layer formed equal to combined thickness of both HAZ and deposit. This hard layer is unable to absorb thermal stresses resulting in the cracking of the deposit. By providing a buffer layer of Alloy 625 followed by a post-weld heat treatment, HAZ formed in the modified 9Cr-1Mo steel is effectively tempered, and HAZ formed during the subsequent deposition of the hardfacing alloy over the Alloy 625 buffer layer is almost completely confined to Alloy 625, which does not harden. This reduces the cracking susceptibility of the deposit. Further, unlike in the case of direct deposition on modified 9Cr-1Mo steel, dilution of the deposit by Ni-base buffer layer does not alter the hardness of the deposit and desired hardness on the deposit surface could be achieved even with lower thickness of the deposit. This gives an option for reducing the recommended thickness of the deposit, which can also reduce the risk of cracking.

  5. Magnetic properties of Pr-Fe-B thick-film magnets deposited on Si substrates with glass buffer layer

    Science.gov (United States)

    Nakano, M.; Kurosaki, A.; Kondo, H.; Shimizu, D.; Yamaguchi, Y.; Yamashita, A.; Yanai, T.; Fukunaga, H.

    2018-05-01

    In order to improve the magnetic properties of PLD-made Pr-Fe-B thick-film magnets deposited on Si substrates, an adoption of a glass buffer layer was carried out. The glass layer could be fabricated under the deposition rate of approximately 70 μm/h on a Si substrate using a Nd-YAG pulse laser in the vacuum atmosphere. The use of the layer enabled us to reduce the Pr content without a mechanical destruction and enhance (BH)max value by approximately 20 kJ/m3 compared with the average value of non-buffer layered Pr-Fe-B films with almost the same thickness. It is also considered that the layer is also effective to apply a micro magnetization to the films deposited on Si ones.

  6. Improved Efficiency of Flexible Organic Light-Emitting Diodes by Insertion of Ultrathin SiO2 Buffer Layers

    Directory of Open Access Journals (Sweden)

    Chien-Jung Huang

    2013-01-01

    Full Text Available An ultrathin hole-injection buffer layer (HBL using silicon dioxide (SiO2 by electron beam evaporation in flexible organic light-emitting diode (FOLED has been fabricated. While the current of the device at constant driving voltage decreases as increasing SiO2 thickness. Compared to the different thicknesses of the buffer layer, the FOLED with the buffer layer of 4 nm showed the highest luminous efficiency. The atomic force microscopy (AFM investigation of indium tin oxide (ITO/SiO2 topography reveals changes at the interface between SiO2 and N,N′-bis-(1-naphthl-diphenyl-1,1′-bipheny-4,4′-diamine (NPB, resulting in ultrathin SiO2 layers being a clear advantage for a FOLED. However, the SiO2 can be expected to be a good buffer layer material and thus enhance the emission performance of the FOLED.

  7. Cooptimization of Adhesion and Power Conversion Efficiency of Organic Solar Cells by Controlling Surface Energy of Buffer Layers.

    Science.gov (United States)

    Lee, Inhwa; Noh, Jonghyeon; Lee, Jung-Yong; Kim, Taek-Soo

    2017-10-25

    Here, we demonstrate the cooptimization of the interfacial fracture energy and power conversion efficiency (PCE) of poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT)-based organic solar cells (OSCs) by surface treatments of the buffer layer. The investigated surface treatments of the buffer layer simultaneously changed the crack path and interfacial fracture energy of OSCs under mechanical stress and the work function of the buffer layer. To investigate the effects of surface treatments, the work of adhesion values were calculated and matched with the experimental results based on the Owens-Wendt model. Subsequently, we fabricated OSCs on surface-treated buffer layers. In particular, ZnO layers treated with poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) simultaneously satisfied the high mechanical reliability and PCE of OSCs by achieving high work of adhesion and optimized work function.

  8. A Feasibility Study of Applying SS 307Si Buffer Layer for Mitigating the Hot Cracking of Ni-Based Weld Overlay

    Science.gov (United States)

    Tsai, Kun-Chao; Jeng, Sheng-Long

    2017-08-01

    The hot cracking behavior of Ni-based Alloy 52M weld overlay with respective SS 307Si and SS 308L buffer layers was investigated. The dilution level of SS 307Si buffer layer is a little higher than that of SS 308L. However, the hot crack length of overlay with SS 307Si buffer layer is shorter and the SS 307Si layer has higher mechanical properties than that of SS 308L layer. As observed by SEM and EBSD, ferrites precipitated in SS 307Si buffer layer are in vermicular skeletons dotted with lathy precipitates, which have a little higher local stain than that of SS 308L weld. However, Alloy 52M weld around SS 307Si fusion boundary has a lower degree of local distortion. The results generalize that the SS 307Si buffer layer is marginally better for reducing hot cracking susceptibility, owing to its lower local stain and slightly higher mechanical strength.

  9. Comparison of different photoresist buffer layers in SPR sensors based on D-shaped POF and gold film

    Science.gov (United States)

    Cennamo, Nunzio; Pesavento, Maria; De Maria, Letizia; Galatus, Ramona; Mattiello, Francesco; Zeni, Luigi

    2017-04-01

    A comparative analysis of two optical fiber sensing platforms is presented. The sensors are based on surface plasmon resonance (SPR) in a D-shaped plastic optical fiber (POF) with a photoresist buffer layer between the exposed POF core and the thin gold film. We show how the sensor's performances change when the photoresist layer changes. The photoresist layers proposed in this analysis are SU-8 3005 and S1813. The experimental results are congruent with the numerical studies and it is instrumental for chemical and bio-chemical applications. Usually, the photoresist layer is required in order to increase the performance of the SPR-POF sensor.

  10. Strain effect in epitaxial VO2 thin films grown on sapphire substrates using SnO2 buffer layers

    Science.gov (United States)

    Kim, Heungsoo; Bingham, Nicholas S.; Charipar, Nicholas A.; Piqué, Alberto

    2017-10-01

    Epitaxial VO2/SnO2 thin film heterostructures were deposited on m-cut sapphire substrates via pulsed laser deposition. By adjusting SnO2 (150 nm) growth conditions, we are able to control the interfacial strain between the VO2 film and SnO2 buffer layer such that the semiconductor-to-metal transition temperature (TC) of VO2 films can be tuned without diminishing the magnitude of the transition. It is shown that in-plane tensile strain and out-of-plane compressive strain of the VO2 film leads to a decrease of Tc. Interestingly, VO2 films on SnO2 buffer layers exhibit a structural phase transition from tetragonal-like VO2 to tetragonal-VO2 during the semiconductor-to-metal transition. These results suggest that the strain generated by SnO2 buffer provides an effective way for tuning the TC of VO2 films.

  11. Morphological modelling of three-phase microstructures of anode layers using SEM images.

    Science.gov (United States)

    Abdallah, Bassam; Willot, François; Jeulin, Dominique

    2016-07-01

    A general method is proposed to model 3D microstructures representative of three-phases anode layers used in fuel cells. The models are based on SEM images of cells with varying morphologies. The materials are first characterized using three morphological measurements: (cross-)covariances, granulometry and linear erosion. They are measured on segmented SEM images, for each of the three phases. Second, a generic model for three-phases materials is proposed. The model is based on two independent underlying random sets which are otherwise arbitrary. The validity of this model is verified using the cross-covariance functions of the various phases. In a third step, several types of Boolean random sets and plurigaussian models are considered for the unknown underlying random sets. Overall, good agreement is found between the SEM images and three-phases models based on plurigaussian random sets, for all morphological measurements considered in the present work: covariances, granulometry and linear erosion. The spatial distribution and shapes of the phases produced by the plurigaussian model are visually very close to the real material. Furthermore, the proposed models require no numerical optimization and are straightforward to generate using the covariance functions measured on the SEM images. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  12. Performance improvement of MEH-PPV:PCBM solar cells using bathocuproine and bathophenanthroline as the buffer layers

    International Nuclear Information System (INIS)

    Liu Xiao Dong; Zhao Su-Ling; Xu Zheng; Zhang Fu-Jun; Zhang Tian-Hui; Gong Wei; Yan Guang; Kong Chao; Wang Yong-Sheng; Xu Xu-Rong

    2011-01-01

    In this work, bathocuproine (BCP) and bathophenanthroline (Bphen), commonly used in small-molecule organic solar cells (OSCs), are adopted as the buffer layers to improve the performance of the polymer solar cells (PSCs) based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV): [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-nm BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen (i) increasing the optical field, and hence the absorption in the active layer, (ii) effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum (Al) interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance (R s ), and (iii) preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode. (interdisciplinary physics and related areas of science and technology)

  13. High-Efficiency and High-Operational-Stability Top-Emitting Organic Light-Emitting Diodes Using Antioxidant Buffer Layer

    Science.gov (United States)

    Murakami, Hajime; Shimizu, Masao; Aratani, Sukekazu; Tanaka, Masahiro

    2009-08-01

    We have succeeded in developing top-emitting organic light-emitting diodes (OLEDs) with high efficiency and high operational stability using an antioxidant buffer layer. V2O5 was selected as the antioxidant buffer layer to suppress the degradation of the organic materials of OLEDs caused by active oxygen during buffer layer deposition and the damage caused by the bombardment of high-energy particles during transparent electrode sputtering. The top-emitting device with a V2O5 buffer layer had the same current density-voltage (J-V) characteristics as the bottom-emitting device with the same material system. The quantum efficiency of the top-emitting device was about 5%, the same as that of the bottom-emitting device. The time required for luminance to drop to 90% of the initial value of the top-emitting device was over 700 h, which is longer than that of the bottom-emitting device (300 h). From X-ray photoelectron spectroscopy (XPS) analysis of the interface between organic materials and V2O5, it was determined that there was no degradation of organic materials under V2O5.

  14. The Influence of an EPS Concrete Buffer Layer Thickness on Debris Dams Impacted by Massive Stones in the Debris Flow

    Directory of Open Access Journals (Sweden)

    Xianbin Yu

    2015-01-01

    Full Text Available The failure of debris dams impacted by the massive stones in a debris flow represents a difficult design problem. Reasonable materials selection and structural design can effectively improve the resistance impact performance of debris dams. Based on the cushioning properties of expanded polystyrene (EPS concrete, EPS concrete as a buffer layer poured on the surface of a rigid debris dam was proposed. A three-dimensional numerical calculation model of an EPS concrete buffer layer/rigid debris dam was established. The single-factor theory revealed change rules for the thickness of the buffer layer concerning the maximal impact force of the rigid debris dam surface through numerical simulation. Moreover, the impact force-time/history curves under different calculation conditions for the rigid debris dam surface were compared. Simulation results showed that the EPS concrete buffer layer can not only effectively extend the impact time of massive stones affecting the debris dam but also reduce the impact force of the rigid debris dam caused by massive stones in the debris flow. The research results provide theoretical guidance for transferring the energy of the massive stone impact, creating a structural design and optimizing debris dams.

  15. The growth of various buffer layer structures and their influence on the quality of (CdHg)Te epilayers

    CSIR Research Space (South Africa)

    Gouws, GJ

    1993-05-01

    Full Text Available The suitability of various buffer layer structures on (100) GaAs for (CdHg)Te growth by organometallic vapour phase epitaxy (OMVPE) was investigated. The preferred epitaxial orientation of (100) GaAs/ (lll) CdTe was found to be unsuitable due...

  16. OPTIMISATION OF BUFFER SIZE FOR ENHANCING QOS OF VIDEO TRAFFIC USING CROSS LAYERED HYBRID TRANSPORT LAYER PROTOCOL APPROACH

    OpenAIRE

    S. Matilda; B. Palaniappan

    2011-01-01

    Video streaming is gaining importance, with the wide popularity of multimedia rich applications in the Internet. Video streams are delay sensitive and require seamless flow for continuous visualization. Properly designed buffers offer a solution to queuing delay. The diagonally opposite QoS metrics associated with video traffic poses an optimization problem, in the design of buffers. This paper is a continuation of our previous work [1] and deals with the design of buffers. It aims at finding...

  17. Optimization of the Energy Level Alignment between the Photoactive Layer and the Cathode Contact Utilizing Solution-Processed Hafnium Acetylacetonate as Buffer Layer for Efficient Polymer Solar Cells.

    Science.gov (United States)

    Yu, Lu; Li, Qiuxiang; Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Wang, Fuzhi; Zhang, Bing; Dai, Songyuan; Lin, Jun; Tan, Zhan'ao

    2016-01-13

    The insertion of an appropriate interfacial buffer layer between the photoactive layer and the contact electrodes makes a great impact on the performance of polymer solar cells (PSCs). Ideal interfacial buffer layers could minimize the interfacial traps and the interfacial barriers caused by the incompatibility between the photoactive layer and the electrodes. In this work, we utilized solution-processed hafnium(IV) acetylacetonate (Hf(acac)4) as an effective cathode buffer layer (CBL) in PSCs to optimize the energy level alignment between the photoactive layer and the cathode contact, with the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) all simultaneously improved with Hf(acac)4 CBL, leading to enhanced power conversion efficiencies (PCEs). Ultraviolet photoemission spectroscopy (UPS) and scanning Kelvin probe microscopy (SKPM) were performed to confirm that the interfacial dipoles were formed with the same orientation direction as the built-in potential between the photoactive layer and Hf(acac)4 CBL, benefiting the exciton separation and electron transport/extraction. In addition, the optical characteristics and surface morphology of the Hf(acac)4 CBL were also investigated.

  18. Orientation-tuning in self-assembled heterostructures induced by a buffer layer

    Science.gov (United States)

    Zhu, Yuanmin; Liu, Pingping; Yu, Rong; Hsieh, Ying-Hui; Ke, Dan; Chu, Ying-Hao; Zhan, Qian

    2014-04-01

    Anisotropic nano-plate structures in self-assembled perovskite-spinel thin films, BiFeO3-NiFe2O4 and BiFeO3-CoFe2O4, which were deposited on (001)c SrRuO3/SrTiO3 and DyScO3 substrates, respectively, have been demonstrated using transmission electron microscopy combined with strain analysis. Unlike the unitary cube-on-cube orientation relationship reported widely, the growth direction of the CoFe2O4 and NiFe2O4 plates was tuned to [011]c while the BiFeO3 matrix kept [001]c in both systems. In particular, a thin stress-sensitive BiFeO3 buffer layer between the spinel nanostructure and the substrate was introduced for providing a complex strain state in both film systems. The novel orientation tuning and the pattern configuration of the heterostructures are mainly attributed to the strain imposed on the films and the anisotropic ledge growth mechanism of spinels.Anisotropic nano-plate structures in self-assembled perovskite-spinel thin films, BiFeO3-NiFe2O4 and BiFeO3-CoFe2O4, which were deposited on (001)c SrRuO3/SrTiO3 and DyScO3 substrates, respectively, have been demonstrated using transmission electron microscopy combined with strain analysis. Unlike the unitary cube-on-cube orientation relationship reported widely, the growth direction of the CoFe2O4 and NiFe2O4 plates was tuned to [011]c while the BiFeO3 matrix kept [001]c in both systems. In particular, a thin stress-sensitive BiFeO3 buffer layer between the spinel nanostructure and the substrate was introduced for providing a complex strain state in both film systems. The novel orientation tuning and the pattern configuration of the heterostructures are mainly attributed to the strain imposed on the films and the anisotropic ledge growth mechanism of spinels. Electronic supplementary information (ESI) available: A schematic of the 3-D relationships in the perovskite-spinel systems and the related HRTEM images are available. See DOI: 10.1039/c3nr06664a

  19. Buffer layer dependence of magnetoresistance effects in Co2Fe0.4Mn0.6Si/MgO/Co50Fe50 tunnel junctions

    Science.gov (United States)

    Sun, Mingling; Kubota, Takahide; Takahashi, Shigeki; Kawato, Yoshiaki; Sonobe, Yoshiaki; Takanashi, Koki

    2018-05-01

    Buffer layer dependence of tunnel magnetoresistance (TMR) effects was investigated in Co2Fe0.4Mn0.6Si (CFMS)/MgO/Co50Fe50 magnetic tunnel junctions (MTJs). Pd, Ru and Cr were selected for the buffer layer materials, and MTJs with three different CFMS thicknesses (30, 5, and 0.8 nm) were fabricated. A maximum TMR ratio of 136% was observed in the Ru buffer layer sample with a 30-nm-thick CFMS layer. TMR ratios drastically degraded for the CFMS thickness of 0.8 nm, and the values were 26% for Cr buffer layer and less than 1% for Pd and Ru buffer layers. From the annealing temperature dependence of the TMR ratios, amounts of interdiffusion and effects from the lattice mismatch were discussed.

  20. The effect of buffer layer on the thermochromic properties of undoped radio frequency sputtered VO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Panagopoulou, M., E-mail: marpanag@mail.ntua.gr [School of Applied Mathematical and Physical Sciences, National Technical University of Athens, GR 157 80, Zografou Campus, Athens (Greece); Gagaoudakis, E. [Physics Department, University of Crete, 71003 Heraklion, Crete (Greece); Institute of Electronic Structure & Laser (IESL), Foundation for Research and Technology — FORTH-Hellas, P.O. Box 1385, Heraklion 70013, Crete (Greece); Aperathitis, E.; Michail, I. [Institute of Electronic Structure & Laser (IESL), Foundation for Research and Technology — FORTH-Hellas, P.O. Box 1385, Heraklion 70013, Crete (Greece); Kiriakidis, G. [Physics Department, University of Crete, 71003 Heraklion, Crete (Greece); Institute of Electronic Structure & Laser (IESL), Foundation for Research and Technology — FORTH-Hellas, P.O. Box 1385, Heraklion 70013, Crete (Greece); Tsoukalas, D.; Raptis, Y.S. [School of Applied Mathematical and Physical Sciences, National Technical University of Athens, GR 157 80, Zografou Campus, Athens (Greece)

    2015-11-02

    Thermochromic (TC) coatings can find use in a wide range of applications. Vanadium dioxide (VO{sub 2}) specifically, can be potentially used as a smart window coating, as it presents a metal-to-semiconductor transition close to the room temperature (T{sub c} = 68 °C). This results in low transmission in the infrared (thermal) part of the spectrum, while preserving its transmittance in the visible. In the present work, vanadium dioxide (VO{sub 2}) thin films with a thickness of ~ 85 nm were prepared by radio frequency sputtering, to investigate the influence of the buffer layer and deposition properties employed, on their thermochromic behavior. The substrates used were uncoated glass and pre-coated glasses with SnO{sub 2} or ZnON as buffer layer. The lowest growth temperature applied was 300 °C, yielding TC-VO{sub 2}, without the necessity of any post-growth treatment. The structure of the VO{sub 2} films was studied by X-ray diffraction and temperature-dependent micro Raman techniques, and the transition temperatures were determined through transmittance measurements. - Highlights: • RF-sputtered thermochromic VO{sub 2}, was grown at 300 °C and 400 °C. • Buffer layers of SnO{sub 2} or ZnON are used over glass. • Low Tc, without post-treatment, for both buffer-layers and T-growth • Thermochromicity of glass/VO{sub 2}, at low T-growth, is improved by ZnON buffer layer.

  1. Modification of SnO2 Anodes by Atomic Layer Deposition for High Performance Lithium Ion Batteries

    KAUST Repository

    Yesibolati, Nulati

    2013-05-01

    Tin dioxide (SnO2) is considered one of the most promising anode materials for Lithium ion batteries (LIBs), due to its large theoretical capacity and natural abundance. However, its low electronic/ionic conductivities, large volume change during lithiation/delithiation and agglomeration prevent it from further commercial applications. In this thesis, we investigate modified SnO2 as a high energy density anode material for LIBs. Specifically two approaches are presented to improve battery performances. Firstly, SnO2 electrochemical performances were improved by surface modification using Atomic Layer Deposition (ALD). Ultrathin Al2O3 or HfO2 were coated on SnO2 electrodes. It was found that electrochemical performances had been enhanced after ALD deposition. In a second approach, we implemented a layer-by-layer (LBL) assembled graphene/carbon-coated hollow SnO2 spheres as anode material for LIBs. Our results indicated that the LBL assembled electrodes had high reversible lithium storage capacities even at high current densities. These superior electrochemical performances are attributed to the enhanced electronic conductivity and effective lithium diffusion, because of the interconnected graphene/carbon networks among nanoparticles of the hollow SnO2 spheres.

  2. Effect of the thickness of the anode electrode catalyst layers on the performance in direct methanol fuel cells

    Science.gov (United States)

    Glass, Dean E.; Olah, George A.; Prakash, G. K. Surya

    2017-06-01

    For the large scale fuel cell manufacture, the catalyst loading and layer thickness are critical factors affecting the performance and cost of membrane electrode assemblies (MEAs). The influence of catalyst layer thicknesses at the anode of a PEM based direct methanol fuel cell (DMFC) has been investigated. Catalysts were applied with the drawdown method with varied thicknesses ranging from 1 mil to 8 mils (1 mil = 25.4 μm) with a Pt/Ru anode loading of 0.25 mg cm-2 to 2.0 mg cm-2. The MEAs with the thicker individual layers (8 mils and 4 mils) performed better overall compared to the those with the thinner layers (1 mil and painted). The peak power densities for the different loading levels followed an exponential decrease of Pt/Ru utilization at the higher loading levels. The highest power density achieved was 49 mW cm-2 with the 4 mil layers at 2.0 mg cm-2 catalyst loading whereas the highest normalized power density was 116 mW mg-1 with the 8 mil layers at 0.25 mg cm-2 loading. The 8 mil drawdowns displayed a 50% and 23% increase in normalized power density compared to the 1 mil drawdowns at 0.25 mg cm-2 and 0.5 mg cm-2 loadings, respectively.

  3. Improving the performance of perovskite solar cells with glycerol-doped PEDOT:PSS buffer layer

    Science.gov (United States)

    Jian-Feng, Li; Chuang, Zhao; Heng, Zhang; Jun-Feng, Tong; Peng, Zhang; Chun-Yan, Yang; Yang-Jun, Xia; Duo-Wang, Fan

    2016-02-01

    In this paper, we investigate the effects of glycerol doping on transmittance, conductivity and surface morphology of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)) (PEDOT:PSS) and its influence on the performance of perovskite solar cells. . The conductivity of PEDOT:PSS is improved obviously by doping glycerol. The maximum of the conductivity is 0.89 S/cm when the doping concentration reaches 6 wt%, which increases about 127 times compared with undoped. The perovskite solar cells are fabricated with a configuration of indium tin oxide (ITO)/PEDOT:PSS/CH3NH3PbI3/PC61BM/Al, where PEDOT:PSS and PC61BM are used as hole and electron transport layers, respectively. The results show an improvement of hole charge transport as well as an increase of short-circuit current density and a reduction of series resistance, owing to the higher conductivity of the doped PEDOT:PSS. Consequently, it improves the whole performance of perovskite solar cell. The power conversion efficiency (PCE) of the device is improved from 8.57% to 11.03% under AM 1.5 G (100 mW/cm2 illumination) after the buffer layer has been modified. Project supported by the National Natural Science Foundation of China (Grant Nos. 61264002, 61166002, 91333206, and 51463011), the Natural Science Foundation of Gansu Province, China (Grant No. 1308RJZA159), the New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0840), the Research Project of Graduate Teacher of Gansu Province, China (Grant No. 2014A-0042), and the Postdoctoral Science Foundation from Lanzhou Jiaotong University, China.

  4. Chemical solution deposited BaPbO3 buffer layers for lead zirconate titanate ferroelectric films

    International Nuclear Information System (INIS)

    Tseng, T.-K.; Wu, J.-M.

    2005-01-01

    Conductive perovskite BaPbO 3 (BPO) films have been prepared successfully by chemical solution deposition method through spin-coating on Pt/Ti/SiO 2 /Si substrates. The choice of baking temperature is a key factor on the development of conducting BPO perovskite phase. When the baking temperature is higher than 350 deg. C, the BPO films contain a high content of BaCO 3 phase after annealing at temperatures higher than 500 deg. C. If the baking temperature is chosen lower than 300 deg. C, such as 200 deg. C, the annealed BPO films consist mostly of perovskite with only traces of BaCO 3 . Choosing 200 deg. C as the baking temperature, the BPO films developed single perovskite phase at temperatures as low as 550 deg. C. The perovskite BPO phase is stable in the range of 550-650 deg. C and the measured sheet resistance of the BPO films is about 2-3 Ω/square. The perovskite BPO film as a buffer layer provides improvement in electric properties of lead zirconate titanate films

  5. Wide-Gap Cu(In,Ga)Se2 Solar Cells with Zn(O,S) Buffer Layers Prepared by Atomic Layer Deposition

    Science.gov (United States)

    Nakashima, Kazuya; Kumazawa, Toyokazu; Kobayashi, Taizo; Mise, Takahiro; Nakada, Tokio

    2012-10-01

    Wide-gap Cu(In0.4,Ga0.6)Se2 solar cells with Zn(O,S) buffer layers deposited by atomic layer deposition (ALD) technique have been investigated. The band-gap energy (Eg) of the Zn(O,S) layer estimated by optical transmission and reflection measurements was varied from 3.2 to 3.6 eV. The solar cells with sulfur (S)-poor Zn(O,S) buffer layers showed a low open-circuit voltage (VOC) owing to the cliff nature of the conduction band offset (CBO). In contrast, the solar cells with S-rich Zn(O,S) buffer layers showed a low short-circuit current density (JSC) owing to the spike nature of CBO. Even if the CBO values were adequate, the best solar cell efficiencies were considerably low. These results suggest that the main cause for the low efficiencies is not interface recombination at the Zn(O,S)/Cu(In,Ga)Se2 interface, but mainly bulk recombination in the Cu(In,Ga)Se2 (CIGS) absorber layer.

  6. Preferential orientation growth of ITO thin film on quartz substrate with ZnO buffer layer by magnetron sputtering technique

    Science.gov (United States)

    Du, Wenhan; Yang, Jingjing; Xiong, Chao; Zhao, Yu; Zhu, Xifang

    2017-07-01

    In order to improve the photoelectric transformation efficiency of thin-film solar cells, one plausible method was to improve the transparent conductive oxides (TCO) material property. In-doped tin oxide (ITO) was an important TCO material which was used as a front contact layer in thin-film solar cell. Using magnetron sputtering deposition technique, we prepared preferential orientation ITO thin films on quartz substrate. XRD and SEM measurements were used to characterize the crystalline structure and morphology of ITO thin films. The key step was adding a ZnO thin film buffer layer before ITO deposition. ZnO thin film buffer layer increases the nucleation center numbers and results in the (222) preferential orientation growth of ITO thin films.

  7. Cu(In,Ga)Se2 solar cells with In2S3 buffer layer deposited by thermal evaporation

    Science.gov (United States)

    Kim, SeongYeon; Rana, Tanka R.; Kim, JunHo; Yun, JaeHo

    2017-12-01

    We report on physical vapor deposition of indium sulfide (In2S3) buffer layers and its application to Cu(In,Ga)Se2 (CIGSe) thin film solar cell. The Indium sulfide buffer layers were evaporated onto CIGSe at various substrate temperatures from room temperature (RT) to 350 °C. The effect of deposition temperature of buffer layers on the solar cell device performance were investigated by analyzing temperature dependent current-voltage ( J- V- T), external quantum efficiency (EQE) and Raman spectroscopy. The fabricated device showed the highest power conversion efficiency of 6.56% at substrate temperature of 250 °C, which is due to the decreased interface recombination. However, the roll-over in J- V curves was observed for solar cell device having buffer deposited at substrate temperature larger than 250 °C. From the measurement results, the interface defect and roll-over related degradation were found to have limitation on the performance of solar cell device.

  8. Tuning the two-dimensional electron liquid at oxide interfaces by buffer-layer-engineered redox reactions

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Green, Robert J.; Sutarto, Ronny

    2017-01-01

    polarities and redox reactions from disordered overlayers grown at room temperature. Using resonant x-ray reflectometry experiments, we quantify redox reactions from oxide overlayers on STO as well as polarity induced electronic reconstruction at epitaxial LSMO/STO interfaces. The analysis reveals how...... these effects can be combined in a STO/LSMO/disordered film trilayer system to yield high mobility modulation doped 2DELs, where the buffer layer undergoes a partial transformation from perovskite to brownmillerite structure. This uncovered interplay between polar discontinuities and redox reactions via buffer...

  9. Selectively Enhanced UV-A Photoresponsivity of a GaN MSM UV Photodetector with a Step-Graded AlxGa1-xN Buffer Layer.

    Science.gov (United States)

    Lee, Chang-Ju; Won, Chul-Ho; Lee, Jung-Hee; Hahm, Sung-Ho; Park, Hongsik

    2017-07-21

    The UV-to-visible rejection ratio is one of the important figure of merits of GaN-based UV photodetectors. For cost-effectiveness and large-scale fabrication of GaN devices, we tried to grow a GaN epitaxial layer on silicon substrate with complicated buffer layers for a stress-release. It is known that the structure of the buffer layers affects the performance of devices fabricated on the GaN epitaxial layers. In this study, we show that the design of a buffer layer structure can make effect on the UV-to-visible rejection ratio of GaN UV photodetectors. The GaN photodetector fabricated on GaN-on-silicon substrate with a step-graded Al x Ga -x N buffer layer has a highly-selective photoresponse at 365-nm wavelength. The UV-to-visible rejection ratio of the GaN UV photodetector with the step-graded Al x Ga 1-x N buffer layer was an order-of-magnitude higher than that of a photodetector with a conventional GaN/AlN multi buffer layer. The maximum photoresponsivity was as high as 5 × 10 - ² A/W. This result implies that the design of buffer layer is important for photoresponse characteristics of GaN UV photodetectors as well as the crystal quality of the GaN epitaxial layers.

  10. Influence of a front buffer layer on the performance of flexible Cadmium sulfide/Cadmium telluride solar cells

    Science.gov (United States)

    Mahabaduge, Hasitha Padmika

    Cadmium telluride (CdTe) solar cells have been developing as a promising candidate for large-scale application of photovoltaic energy conversion and have become the most commercially successful polycrystalline thin-film solar module material. In scaling up from small cells to large-area modules, inevitably non-uniformities across the large area will limit the performance of the large cell or module. The effects of these non-uniformities can be reduced by introducing a thin, high-resistivity transparent buffer layer between the conductive electrodes and the semiconductor diode. ZnO is explored in this dissertation as a high-resistivity transparent buffer layer for sputtered CdTe solar cells and efficiencies over 15% have been achieved on commercially available Pilkington TEC15M glass substrates. The highest open-circuit voltage of 0.858V achieved using the optimized ZnO buffer layer is among the best reported in the literature. The properties of ZnO:Al as a buffer are also investigated. We have shown that ZnO:Al can serve both as a transparent conducting oxide layer as well as a high-resistivity transparent layer for CdTe solar cells. ZnO:Al reactively sputtered with oxygen can give the necessary resistivities that allow it to be used as a high-resistivity transparent layer. Glass is the most common choice as the substrate for solar cells fabricated in the superstrate configuration due to its transparency and mechanical rigidity. However flexible substrates offer the advantages of light weight, high flexibility, ease of integrability and higher throughput through roll-to-roll processing over glass. This dissertation presents significant improvements made to flexible CdTe solar cells reporting an efficiency of 14% on clear KaptonRTM flexible polyimide substrates. Our efficiency of 14% is, to our knowledge, the best for any flexible CdTe cell reported in literature.

  11. Layered oxygen-deficient double perovskite as an efficient and stable anode for direct hydrocarbon solid oxide fuel cells.

    Science.gov (United States)

    Sengodan, Sivaprakash; Choi, Sihyuk; Jun, Areum; Shin, Tae Ho; Ju, Young-Wan; Jeong, Hu Young; Shin, Jeeyoung; Irvine, John T S; Kim, Guntae

    2015-02-01

    Different layered perovskite-related oxides are known to exhibit important electronic, magnetic and electrochemical properties. Owing to their excellent mixed-ionic and electronic conductivity and fast oxygen kinetics, cation layered double perovskite oxides such as PrBaCo2O5 in particular have exhibited excellent properties as solid oxide fuel cell oxygen electrodes. Here, we show for the first time that related layered materials can be used as high-performance fuel electrodes. Good redox stability with tolerance to coking and sulphur contamination from hydrocarbon fuels is demonstrated for the layered perovskite anode PrBaMn2O5+δ (PBMO). The PBMO anode is fabricated by in situ annealing of Pr0.5Ba0.5MnO3-δ in fuel conditions and actual fuel cell operation is demonstrated. At 800 °C, layered PBMO shows high electrical conductivity of 8.16 S cm(-1) in 5% H2 and demonstrates peak power densities of 1.7 and 1.3 W cm(-2) at 850 °C using humidified hydrogen and propane fuels, respectively.

  12. Aqueous Chemical Solution Deposition of Novel, Thick and Dense Lattice-Matched Single Buffer Layers Suitable for YBCO Coated Conductors: Preparation and Characterization

    Directory of Open Access Journals (Sweden)

    Isabel van Driessche

    2012-09-01

    Full Text Available In this work we present the preparation and characterization of cerium doped lanthanum zirconate (LCZO films and non-stoichiometric lanthanum zirconate (LZO buffer layers on metallic Ni-5% W substrates using chemical solution deposition (CSD, starting from aqueous precursor solutions. La2Zr2O7 films doped with varying percentages of Ce at constant La concentration (La0.5CexZr1−xOy were prepared as well as non-stoichiometric La0.5+xZr0.5−xOy buffer layers with different percentages of La and Zr ratios. The variation in the composition of these thin films enables the creation of novel buffer layers with tailored lattice parameters. This leads to different lattice mismatches with the YBa2Cu3O7−x (YBCO superconducting layer on top and with the buffer layers or substrate underneath. This possibility of minimized lattice mismatch should allow the use of one single buffer layer instead of the current complicated buffer architectures such as Ni-(5% W/LZO/LZO/CeO2. Here, single, crack-free LCZO and non-stoichiometric LZO layers with thicknesses of up to 140 nm could be obtained in one single CSD step. The crystallinity and microstructure of these layers were studied by XRD, and SEM and the effective buffer layer action was studied using XPS depth profiling.

  13. Preparation of SmBiO{sub 3} buffer layer on YSZ substrate by an improved chemical solution deposition route

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaolei [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Superconductivity and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Pu, Minghua, E-mail: mhpu@home.swjtu.edu.cn [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Superconductivity and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Yong [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Superconductivity and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wale, Sydney, NSW 2052 (Australia)

    2016-12-15

    Highlights: • The proper conditions for SBO growth are 794 °C for 60 min in flowing Ar gas, the temperature of epitaxial growth is relatively low. • The total time by SSD technique for organic solvent removing, salts decomposition and layer growth is not up to 2 h, which are much less than that needed for traditional CSD of over 10 h. • SBO layer on YSZ prepared by SSD technique are suitable for the growth of YBCO, The results may be the usable reference for continuous preparation of SBO buffer layer on IBAD-YSZ/Ni-based alloy tapes. - Abstract: A quick route for chemical solution deposition (CSD) has been developed to prepare SmBiO{sub 3} (SBO) layers on yttria stabilized zirconia (YSZ) substrates rapidly by using of solid state decomposition (SSD) technique. The proper conditions for volatilization of lactic acid, which as solvent in precursor coated layer, and SBO growth are 115°C for 30 min and 794°C for 60 min in flowing Ar gas. The coated layers are amorphous structure of mixture oxides and quasi-crystal structure of SBO before and after growth, respectively. The total time by this quick CSD route for organic solvent volatilization, salts decomposed and layer growth is not up to 2 h, which are much less than that needed for traditional CSD of over 10 h. SBO layer is directly epitaxial growth on YSZ substrate without any lattice rotation. SBO layer prepared by this quick route as well as that by traditional route are suitable for the growth of YBCO. The superconducting transition temperature and critical current density of the coated YBCO layer on SBO/YSZ obtained by this quick route are up to 90 K and 1.66 MA/cm{sup 2}. These results may be the usable reference for continuous preparation of SBO buffer layer on IBAD-YSZ/Ni-based alloy tapes.

  14. Simulating characteristics of Si/Ge tandem monolithic solar cell with Si1-xGex buffer layer

    Directory of Open Access Journals (Sweden)

    Gnilenko A. B.

    2015-12-01

    Full Text Available In spite of many efforts to propose new semiconductor materials and sophisticated constructions of solar cells, crystalline silicone remains the main photovoltaic material widely used up to now. There are various methods to enhance the efficiency of silicone solar cells. One of them is to combine silicone with an additional semiconductor material with the different bandgap to form a tandem construction. For example, the germanium sub-cell used as the bottom cascade for the silicone sub-cell in the tandem monolithic solar cell makes it possible to utilize the "red" sub-band of solar spectra increasing overall solar cell efficiency. The problem of the 4.2% mismatch in lattice constant between Si and Ge can be resolved in such a case by the use of SiGe buffer layer. In the paper the results of the computer simulation for Si/Ge tandem monolithic solar cell with Si1-xGex buffer layer are presented. In the solar cell under consideration, the step graded Si1-xGex buffer layer is located between the top silicone and the bottom germanium cascades to reduce the threading dislocation density in mismatched materials. The cascades are commutated by the use of the germanium tunnel diode between the bottom sub-cell and the buffer layer. For the solar cell modeling, the physically-based device simulator ATLAS of Silvaco TCAD software is employed to predict the electrical behavior of the semiconductor structure and to provide a deep insight into the internal physical processes. The voltage-current characteristic, photovoltaic parameters and the distribution of basic physical values are obtained for the investigated tandem solar cell. The influence of layer thicknesses on the photovoltaic parameters is studied. The calculated efficiency of the tandem solar cell reaches 13% which is a quarter more than the efficiency of a simple silicone solar cell with the same constructive parameters and under the same illumination conditions.

  15. Probing temperature gradients within the GaN buffer layer of AlGaN/GaN high electron mobility transistors with Raman thermography

    International Nuclear Information System (INIS)

    Hodges, C.; Pomeroy, J.; Kuball, M.

    2014-01-01

    We demonstrate the ability of confocal Raman thermography using a spatial filter and azimuthal polarization to probe vertical temperature gradients within the GaN buffer layer of operating AlGaN/GaN high electron mobility transistors. Temperature gradients in the GaN layer are measured by using offset focal planes to minimize the contribution from different regions of the GaN buffer. The measured temperature gradient is in good agreement with a thermal simulation treating the GaN thermal conductivity as homogeneous throughout the layer and including a low thermal conductivity nucleation layer to model the heat flow between the buffer and substrate

  16. Probing temperature gradients within the GaN buffer layer of AlGaN/GaN high electron mobility transistors with Raman thermography

    Energy Technology Data Exchange (ETDEWEB)

    Hodges, C., E-mail: chris.hodges@bristol.ac.uk; Pomeroy, J.; Kuball, M. [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2014-02-14

    We demonstrate the ability of confocal Raman thermography using a spatial filter and azimuthal polarization to probe vertical temperature gradients within the GaN buffer layer of operating AlGaN/GaN high electron mobility transistors. Temperature gradients in the GaN layer are measured by using offset focal planes to minimize the contribution from different regions of the GaN buffer. The measured temperature gradient is in good agreement with a thermal simulation treating the GaN thermal conductivity as homogeneous throughout the layer and including a low thermal conductivity nucleation layer to model the heat flow between the buffer and substrate.

  17. Buffer optimization for crack-free GaN epitaxial layers grown on Si(1 1 1) substrate by MOCVD

    International Nuclear Information System (INIS)

    Arslan, Engin; Ozbay, Ekmel; Ozturk, Mustafa K; Ozcelik, Suleyman; Teke, Ali

    2008-01-01

    We report the growth of GaN films on the Si(1 1 1) substrate by metalorganic chemical vapour phase deposition (MOCVD). Different buffer layers were used to investigate their effects on the structural and optical properties of GaN layers. A series of GaN layers were grown on Si(1 1 1) with different buffer layers and buffer thicknesses and were characterized by Nomarski microscopy, atomic force microscopy, high-resolution x-ray diffraction (XRD) and photoluminescence (PL) measurements. We first discuss the optimization of the LT-AlN/HT-AlN/Si(1 1 1) templates and then the optimization of the graded AlGaN intermediate layers. In order to prevent stress relaxation, step-graded AlGaN layers were introduced along with a crack-free GaN layer of thickness exceeding 2.6 μm. The XRD and PL measurements results confirmed that a wurtzite GaN was successfully grown. The resulting GaN film surfaces were flat, mirror-like and crack-free. The mosaic structure in the GaN layers was investigated. With a combination of Williamson-Hall measurements and the fitting of twist angles, it was found that the buffer thickness determines the lateral coherence length, vertical coherence length, as well as the tilt and twist of the mosaic blocks in GaN films. The PL spectra at 8 K show that a strong band edge photoluminescence of GaN on Si (1 1 1) emits light at an energy of 3.449 eV with a full width at half maximum (FWHM) of approximately 16 meV. At room temperature, the peak position and FWHM of this emission become 3.390 eV and 58 meV, respectively. The origin of this peak was attributed to the neutral donor bound exciton. It was found that the optimized total thickness of the AlN and graded AlGaN layers played a very important role in the improvement of quality and in turn reduced the cracks during the growth of GaN/Si(1 1 1) epitaxial layers

  18. Study of the influence of Nb buffer layer on the exchange coupling induced at the Co/IrMn interface

    Energy Technology Data Exchange (ETDEWEB)

    Merino, I.L.C., E-mail: isabel5cas@gmail.com [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil); Figueiredo, L.C. [Instituto de Física, Universidade de Brasília, Brasília 70910-900 (Brazil); Passamani, E.C.; Nascimento, V.P. [Departamento de Física, Universidade Federal do Espírito Santo, Vitória 29075-910 (Brazil); Pelegrini, F. [Instituto de Física, Universidade Federal de Goiás, Goiânia 74560-900 (Brazil); Baggio Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180 (Brazil)

    2017-06-15

    Highlights: • Nb buffer layer favors smooth/rough Co/IrMn interfaces, depending on its thickness. • Double and single-like hysteresis loop features depend on the Nb thickness. • Co uniaxial anisotropy induced exchange-bias in as-deposited sample. • Uniaxial and exchange-bias anisotropy directions depend on the Nb thickness. • Thicker Nb favors non-collinear anisotropies, while thinner Nb favors collinear. - Abstract: Hybrid Nb(t{sub Nb})/Co(10 nm)/IrMn(15 nm)/Nb(10 nm) heterostructured materials were prepared by DC Magnetron Sputtering and systematically studied by X-ray, magnetization and ferromagnetic resonance techniques. For thinner Nb buffer layer (≤10 nm), it was found that there is an inter-diffusion at Co/IrMn interface, which favors double-like hysteresis loop. For thicker Nb layers, however, a gradual transition from double to single-like hysteresis loops is observed and it is associated with the reduction of the Nb roughness, which also enhances the exchange coupling at the Co/IrMn interface. Nb grown on IrMn layer induces the formation of an NbIrMn alloy layer, while no evidence of inter-diffusion at the Co/Nb interface is observed. For rougher Nb buffer layers (t{sub Nb} < 50 nm), exchange bias and Co uniaxial anisotropies are pointing at the same direction (β∼zero), but for smoother Nb buffer layer (t{sub Nb} = 50 nm) a β angle of 150{sup o} is found. Exchange bias effect was measured in as-prepared and in field-cooled samples; being its presence, in as-prepared sample, attributed to the unidirectional anisotropy of the Co layer (its intensity is modified in case of sample with a CoIrMn alloy layer). Considering that the Si/Nb/Co/IrMn interfaces have different β values (t{sub Nb} = 35 and 50 nm), a study of the influence of magnetization direction, governed by exchange-biased layers, on superconducting properties of Nb films can be successfully done in this hybrid system.

  19. Revisiting Surface Modification of Graphite: Dual-Layer Coating for High-Performance Lithium Battery Anode Materials.

    Science.gov (United States)

    Song, Gyujin; Ryu, Jaegeon; Ko, Seunghee; Bang, Byoung Man; Choi, Sinho; Shin, Myoungsoo; Lee, Sang-Young; Park, Soojin

    2016-06-06

    Surface modification of electrode active materials has garnered considerable attention as a facile way to meet stringent requirements of advanced lithium-ion batteries. Here, we demonstrated a new coating strategy based on dual layers comprising antimony-doped tin oxide (ATO) nanoparticles and carbon. The ATO nanoparticles are synthesized via a hydrothermal method and act as electronically conductive/electrochemically active materials. The as-synthesized ATO nanoparticles are introduced on natural graphite along with citric acid used as a carbon precursor. After carbonization, the carbon/ATO-decorated natural graphite (c/ATO-NG) is produced. In the (carbon/ATO) dual-layer coating, the ATO nanoparticles coupled with the carbon layer exhibit unprecedented synergistic effects. The resultant c/ATO-NG anode materials display significant improvements in capacity (530 mA h g(-1) ), cycling retention (capacity retention of 98.1 % after 50 cycles at a rate of C/5), and low electrode swelling (volume expansion of 38 % after 100 cycles) which outperform that of typical graphite materials. Furthermore, a full-cell consisting of a c/ATO-NG anode and an LiNi0.5 Mn1.5 O4 cathode presents excellent cycle retention (capacity retention of >80 % after 100 cycles). We envision that the dual-layer coating concept proposed herein opens a new route toward high-performance anode materials for lithium-ion batteries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Amorphous TiO2 Shells: A Vital Elastic Buffering Layer on Silicon Nanoparticles for High-Performance and Safe Lithium Storage.

    Science.gov (United States)

    Yang, Jianping; Wang, Yunxiao; Li, Wei; Wang, Lianjun; Fan, Yuchi; Jiang, Wan; Luo, Wei; Wang, Yang; Kong, Biao; Selomulya, Cordelia; Liu, Hua Kun; Dou, Shi Xue; Zhao, Dongyuan

    2017-12-01

    Smart surface coatings of silicon (Si) nanoparticles are shown to be good examples for dramatically improving the cyclability of lithium-ion batteries. Most coating materials, however, face significant challenges, including a low initial Coulombic efficiency, tedious processing, and safety assessment. In this study, a facile sol-gel strategy is demonstrated to synthesize commercial Si nanoparticles encapsulated by amorphous titanium oxide (TiO 2 ), with core-shell structures, which show greatly superior electrochemical performance and high-safety lithium storage. The amorphous TiO 2 shell (≈3 nm) shows elastic behavior during lithium discharging and charging processes, maintaining high structural integrity. Interestingly, it is found that the amorphous TiO 2 shells offer superior buffering properties compared to crystalline TiO 2 layers for unprecedented cycling stability. Moreover, accelerating rate calorimetry testing reveals that the TiO 2 -encapsulated Si nanoparticles are safer than conventional carbon-coated Si-based anodes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Three-Dimensional Finite Element Simulations for the Thermal Characteristics of PCRAMs with Different Buffer Layer Materials

    International Nuclear Information System (INIS)

    Yue-Feng, Gong; Zhi-Tang, Song; Yun, Ling; Yan, Liu; Yi-Jin, Li; Song-Lin, Feng

    2010-01-01

    Simulation of the heat consumption in phase change random access memories (PCRAMs) is investigated by a three-dimensional finite element model. It is revealed that the thermal conductivity and electrical conductivity of the buffer layer are crucial in controlling the heating efficiency in RESET process. The buffer layer materials W, TiN, WO 3 , TiO 2 and poly-germanium (poly-Ge) are applied in the simulation respectively, and compared with each other. The simulation results show that limitation of electrical conductivity is effective on heating efficiency and the limitation of thermal conductivity is important on the reliable RESET process. (cross-disciplinary physics and related areas of science and technology)

  2. Enhanced magnetic properties of chemical solution deposited BiFeO3 thin film with ZnO buffer layer

    International Nuclear Information System (INIS)

    Rajalakshmi, R.; Kambhala, Nagaiah; Angappane, S.

    2012-01-01

    Highlights: ► Enhanced magnetization of BiFeO 3 is important for strong magnetoelectric coupling. ► BiFeO 3 film with ZnO buffer layer was successfully synthesized by chemical method. ► Magnetization of BiFeO 3 has increased by more than 10 times with ZnO buffer layer. ► A mechanism for enhancement in ferromagnetism of BiFeO 3 film is proposed. - Abstract: Magnetic properties of BiFeO 3 films deposited on Si substrates with and without ZnO buffer layer have been studied in this work. We adopted the chemical solution deposition method for the deposition of BiFeO 3 as well as ZnO films. The x-ray diffraction measurements on the deposited films confirm the formation of crystalline phase of BiFeO 3 and ZnO films, while our electron microscopy measurements help to understand the morphology of few micrometers thick films. It is found that the deposited ZnO film exhibit a hexagonal particulate surface morphology, whereas BiFeO 3 film fully covers the ZnO surface. Our magnetic measurements reveal that the magnetization of BiFeO 3 has increased by more than ten times in BiFeO 3 /ZnO/Si film compared to BiFeO 3 /Si film, indicating the major role played by ZnO buffer layer in enhancing the magnetic properties of BiFeO 3 , a technologically important multiferroic material.

  3. Growth mechanisms of GaSb heteroepitaxial films on Si with an AlSb buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Vajargah, S. Hosseini; Botton, G. A. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Ghanad-Tavakoli, S. [Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Preston, J. S.; Kleiman, R. N. [Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada)

    2013-09-21

    The initial growth stages of GaSb epilayers on Si substrates and the role of the AlSb buffer layer were studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Heteroepitaxy of GaSb and AlSb on Si both occur by Volmer-Weber (i.e., island mode) growth. However, the AlSb and GaSb islands have distinctly different characteristics as revealed through an atomic-resolution structural study using Z-contrast of HAADF-STEM imaging. While GaSb islands are sparse and three dimensional, AlSb islands are numerous and flattened. The introduction of 3D island-forming AlSb buffer layer facilitates the nucleation of GaSb islands. The AlSb islands-assisted nucleation of GaSb islands results in the formation of drastically higher quality planar film at a significantly smaller thickness of films. The interface of the AlSb and GaSb epilayers with the Si substrate was further investigated with energy dispersive X-ray spectrometry to elucidate the key role of the AlSb buffer layer in the growth of GaSb epilayers on Si substrates.

  4. Growth mechanisms of GaSb heteroepitaxial films on Si with an AlSb buffer layer

    International Nuclear Information System (INIS)

    Vajargah, S. Hosseini; Botton, G. A.; Ghanad-Tavakoli, S.; Preston, J. S.; Kleiman, R. N.

    2013-01-01

    The initial growth stages of GaSb epilayers on Si substrates and the role of the AlSb buffer layer were studied by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Heteroepitaxy of GaSb and AlSb on Si both occur by Volmer-Weber (i.e., island mode) growth. However, the AlSb and GaSb islands have distinctly different characteristics as revealed through an atomic-resolution structural study using Z-contrast of HAADF-STEM imaging. While GaSb islands are sparse and three dimensional, AlSb islands are numerous and flattened. The introduction of 3D island-forming AlSb buffer layer facilitates the nucleation of GaSb islands. The AlSb islands-assisted nucleation of GaSb islands results in the formation of drastically higher quality planar film at a significantly smaller thickness of films. The interface of the AlSb and GaSb epilayers with the Si substrate was further investigated with energy dispersive X-ray spectrometry to elucidate the key role of the AlSb buffer layer in the growth of GaSb epilayers on Si substrates

  5. Enhanced Efficiency of Polymer Light-Emitting Diodes by Dispersing Dehydrated Nanotube Titanic Acid in the Hole-buffer Layer

    Energy Technology Data Exchange (ETDEWEB)

    Qian, L., E-mail: qian_lei@126.com; Xu, Z.; Teng, F.; Duan, X.-X. [Beijing Jiaotong University, Institute of Optoelectronic Technology (China); Jin, Z.-S.; Du, Z.-L. [Henan University, Key Laboratory on special functional materials (China); Li, F.-S.; Zheng, M.-J. [State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Peking University, Department of Physics (China); Wang, Y.-S. [Beijing Jiaotong University, Institute of Optoelectronic Technology (China)

    2007-06-15

    Efficiency of polymer light-emitting diodes (PLEDs) with poly(2-methoxy-5-(2-ethyl hexyloxy)-p-phenylene vinylene) (MEH-PPV) as an emitting layer was improved if a dehydrated nanotubed titanic acid (DNTA) doped hole-buffer layer polyethylene dioxythiophene (PEDOT) was used. Photoluminescence (PL) and Raman spectra indicated a stronger interaction between DNTA and sulfur atom in thiophene of PEDOT, which suppresses the chemical interaction between vinylene of MEH-PPV and thiophene of PEDOT. The interaction decreases the defect states in an interface region to result in enhancement in device efficiency, even though the hole transporting ability of PEDOT was decreased.

  6. Molecular Beam Epitaxy of GaSb on GaAs Substrates with AlSb Buffer Layers

    International Nuclear Information System (INIS)

    Zhi-Qiang, Zhou; Ying-Qiang, Xu; Rui-Ting, Hao; Bao, Tang; Zheng-Wei, Ren; Zhi-Chuan, Niu

    2009-01-01

    We investigate the molecular beam epitaxy growth of GaSb films on GaAs substrates using AlSb buffer layers. Optimization of AlSb growth parameter is aimed at obtaining high GaSb crystal quality and smooth GaSb surface. The optimized growth temperature and thickness of AlSb layers are found to be 450° C and 2.1 nm, respectively. A rms surface roughness of 0.67nm over 10 × 10 μm 2 is achieved as a 0.5μm GaSb film is grown under optimized conditions

  7. Enhanced Efficiency of Polymer Light-Emitting Diodes by Dispersing Dehydrated Nanotube Titanic Acid in the Hole-buffer Layer

    International Nuclear Information System (INIS)

    Qian, L.; Xu, Z.; Teng, F.; Duan, X.-X.; Jin, Z.-S.; Du, Z.-L.; Li, F.-S.; Zheng, M.-J.; Wang, Y.-S.

    2007-01-01

    Efficiency of polymer light-emitting diodes (PLEDs) with poly(2-methoxy-5-(2-ethyl hexyloxy)-p-phenylene vinylene) (MEH-PPV) as an emitting layer was improved if a dehydrated nanotubed titanic acid (DNTA) doped hole-buffer layer polyethylene dioxythiophene (PEDOT) was used. Photoluminescence (PL) and Raman spectra indicated a stronger interaction between DNTA and sulfur atom in thiophene of PEDOT, which suppresses the chemical interaction between vinylene of MEH-PPV and thiophene of PEDOT. The interaction decreases the defect states in an interface region to result in enhancement in device efficiency, even though the hole transporting ability of PEDOT was decreased

  8. The effects of ZnO buffer layers on the properties of phosphorus doped ZnO thin films grown on sapphire by pulsed laser deposition

    International Nuclear Information System (INIS)

    Kim, K-W; Lugo, F J; Lee, J H; Norton, D P

    2012-01-01

    The properties of phosphorus doped ZnO thin films grown on sapphire by pulsed laser deposition were examined, specifically focusing on the effects of undoped ZnO buffer layers. In particular, buffer layers were grown under different conditions; the transport properties of as-deposited and rapid thermal annealed ZnO:P films were then examined. As-deposited films showed n-type conductivity. After rapid thermal annealing, the film on buffer layer grown at a low temperature showed the conversion of carrier type to p-type for specific growth conditions while the films deposited on buffer layer grown at a high temperature remained n-type regardless of growth condition. The films deposited on buffer layer grown at a low temperature showed higher resistivity and more significant change of the transport properties upon rapid thermal annealing. These results suggest that more dopants are incorporated in films with higher defect density. This is consistent with high resolution x-ray diffraction results for phosphorus doped ZnO films on different buffer layers. In addition, the microstructure of phosphorus doped ZnO films is substantially affected by the buffer layer.

  9. A High-Performing Sulfur-Tolerant and Redox-Stable Layered Perovskite Anode for Direct Hydrocarbon Solid Oxide Fuel Cells

    Science.gov (United States)

    Ding, Hanping; Tao, Zetian; Liu, Shun; Zhang, Jiujun

    2015-01-01

    Development of alternative ceramic oxide anode materials is a key step for direct hydrocarbon solid oxide fuel cells (SOFCs). Several lanthanide based layered perovskite-structured oxides demonstrate outstanding oxygen diffusion rate, favorable electronic conductivity, and good oxygen surface exchange kinetics, owing to A-site ordered structure in which lanthanide and alkali-earth ions occupy alternate (001) layers and oxygen vacancies are mainly located in [LnOx] planes. Here we report a nickel-free cation deficient layered perovskite, (PrBa)0.95(Fe0.9Mo0.1)2O5 + δ (PBFM), for SOFC anode, and this anode shows an outstanding performance with high resistance against both carbon build-up and sulfur poisoning in hydrocarbon fuels. At 800 °C, the layered PBFM showed high electrical conductivity of 59.2 S cm−1 in 5% H2 and peak power densities of 1.72 and 0.54 W cm−2 using H2 and CH4 as fuel, respectively. The cell exhibits a very stable performance under a constant current load of 1.0 A cm−2. To our best knowledge, this is the highest performance of ceramic anodes operated in methane. In addition, the anode is structurally stable at various fuel and temperature conditions, suggesting that it is a feasible material candidate for high-performing SOFC anode. PMID:26648509

  10. UV-treated graphene oxide as anode interfacial layers for P3HT : PCBM solar cells

    Science.gov (United States)

    Cheng, Cheng-En; Tsai, Cheng-Wei; Pei, Zingway; Lin, Tsung-Wu; Chang, Chen-Shiung; Shih-Sen Chien, Forest

    2015-06-01

    Solution-processable graphene oxide (GO) ultrathin films were introduced as anode interfacial layers (AILs) for polymer solar cells (PSCs). The photovoltaic performance of PSCs containing thermal- and UV-treated GO was comparable to that of PSCs with conventional poly(3,4-ethyledioxythiphene):poly(styrenesulfonate) AILs. UV treatment induced the surface activation of GO; an increase in the work function of UV-treated GO improved the energy band alignment at the GO/poly(3-hexylthiophene) interface, which accounted for the efficient hole collection and photovoltaic performance of PSCs with treated GO.

  11. Cd-free CIGS solar cells with buffer layer based on the In2S3 derivatives.

    Science.gov (United States)

    Kim, Kihwan; Larina, Liudmila; Yun, Jae Ho; Yoon, Kyung Hoon; Kwon, HyukSang; Ahn, Byung Tae

    2013-06-21

    This study guided by device evaluations was conducted to reveal the reasons for the loss of the photo-generated carriers in CIGS cells with the buffer based on In2S3 derivatives. Chemical bath deposited Inx(OOH,S)y films have been employed as a Cd-free buffer layers. When compared to solar cells with CdS buffer layer, the Cu0.9(In0.7,Ga0.3)Se2.1 (Eg = 1.18 eV) cells with the Inx(OOH,S)y buffer exhibited strong voltage-dependent carrier collection and poor spectral response above 500 nm, presumably, due to energy barrier at the junction. In order to improve the charge collection by upward shift of the conduction band minimum of CIGS absorber, Inx(OOH,S)y/Cu0.9(In0.55,Ga0.45)Se2.1 (Eg = 1.30 eV) solar cells were also fabricated and their spectral responses were examined. When compared to the Cu0.9(In0.7,Ga0.3)Se2.1 cells, the improved spectral response and voltage dependent carrier collection were obtained. Nevertheless, considerable loss in charge collection above 500 nm was still observed. The efficiency reached 9.3% while the Cu0.9(In0.7,Ga0.3)Se2.1 cell exhibited only the efficiency of 3.4%. Finally, CIGS (Eg = 1.18 eV) solar cells with n-ZnO/i-ZnO/Inx(OOH,S)y/CdS/CIGS and n-ZnO/i-ZnO/CdS/Inx(OOH,S)y/CIGS configurations were fabricated. The influence of the TCO/buffer interface on the device characteristics was also addressed by means of comparison between the characteristics of two cells employing different interfaces. A 13.0% efficient cell has been achieved from n-ZnO/i-ZnO/CdS/Inx(OOH,S)y/CIGS configuration. The obtained data suggested that the limitation of the device efficiency was mainly related to the i-ZnO/Inx(OOH,S)y interface. The experimental results provide the knowledge base for further optimization of the interface properties to form high-quality p-n junction in the CIGS solar cells employing the CBD In2S3 buffer layer.

  12. Crystallinity and superconductivity of as-grown MgB2 thin films with AlN buffer layers

    International Nuclear Information System (INIS)

    Tsujimoto, K.; Shimakage, H.; Wang, Z.; Kaya, N.

    2005-01-01

    The effects of aluminum nitride (AlN) buffer layers on the superconducting properties of MgB 2 thin film were investigated. The AlN buffer layers and as-grown MgB 2 thin films were deposited in situ using the multiple-target sputtering system. The best depositing condition for the AlN/MgB 2 bi-layer occurred when the AlN was deposited on c-cut sapphire substrates at 290 deg. C. The crystallinity of the AlN/MgB 2 bi-layer was studied using the XRD φ-scan and it showed that AlN and MgB 2 had the same in-plane alignment rotated at an angle of 30 deg. as compared to c-cut sapphire. The critical temperature of the MgB 2 film was 29.8 K and the resistivity was 50.0 μΩ cm at 40 K

  13. Comparative electrochemical analysis of crystalline and amorphous anodized iron oxide nanotube layers as negative electrode for LIB.

    Science.gov (United States)

    Pervez, Syed Atif; Kim, Doohun; Farooq, Umer; Yaqub, Adnan; Choi, Jung-Hee; Lee, You-Jin; Doh, Chil-Hoon

    2014-07-23

    This work is a comparative study of the electrochemical performance of crystalline and amorphous anodic iron oxide nanotube layers. These nanotube layers were grown directly on top of an iron current collector with a vertical orientation via a simple one-step synthesis. The crystalline structures were obtained by heat treating the as-prepared (amorphous) iron oxide nanotube layers in ambient air environment. A detailed morphological and compositional characterization of the resultant materials was performed via transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Raman spectroscopy. The XRD patterns were further analyzed using Rietveld refinements to gain in-depth information on their quantitative phase and crystal structures after heat treatment. The results demonstrated that the crystalline iron oxide nanotube layers exhibit better electrochemical properties than the amorphous iron oxide nanotube layers when evaluated in terms of the areal capacity, rate capability, and cycling performance. Such an improved electrochemical response was attributed to the morphology and three-dimensional framework of the crystalline nanotube layers offering short, multidirectional transport lengths, which favor rapid Li(+) ions diffusivity and electron transport.

  14. Studies on Ba(2)YNbO(6) Buffer Layers for Subsequent YBa(2)Cu(3)O(7-x) Film Growth

    National Research Council Canada - National Science Library

    Sathiraju, Srinivas; Barnes, Paul N; Varanasi, Chakrapani; Wheeler, Robert

    2004-01-01

    In this paper, we are reporting a dielectric oxide buffer Ba(2)YNbO(6) (BYNO) and its performance on various substrates for a potential buffer layer for the growth of YBa(2)Cu(3)O(7-x) (YBCO) coated conductors. Ba(2)YNbO(6...

  15. Geobacter Dominates the Inner Layers of a Stratified Biofilm on a Fluidized Anode During Brewery Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    Sara Tejedor-Sanz

    2018-03-01

    Full Text Available In this study, we designed a microbial electrochemical fluidized bed reactor (ME-FBR, with an electroconductive anodic bed made of activated carbon particles for treating a brewery wastewater. Under a batch operating mode, acetate and propionate consumption rates were 13-fold and 2.4-fold higher, respectively, when the fluidized anode was polarized (0.2 V with respect to open circuit conditions. Operating in a continuous mode, this system could effectively treat the brewery effluent at organic loading rates (OLR over 1.7 kg m-3NRV d-1 and with removal efficiencies of 95 ± 1.4% (hydraulic retention time of 1 day and an influent of 1.7 g-COD L-1. The coulombic efficiency values highly depended upon the OLR applied, and varied from a 56 ± 15% to 10 ± 1%. Fluorescence in situ hybridization (FISH analysis revealed a relative high abundance of Geobacter species (ca. 20%, and clearly showed a natural microbial stratification. Interestingly, the Geobacter cluster was highly enriched in the innermost layers of the biofilm (thickness of 10 μm, which were in contact with the electroconductive particles of bed, whereas the rest of bacteria were located in the outermost layers. To our knowledge, this is the first time that such a clear microbial stratification has been observed on an anode-respiring biofilm. Our results revealed the relevant role of Geobacter in switching between the electrode and other microbial communities performing metabolic reactions in the outermost environment of the biofilm.

  16. Effects of buffer layer on the structural and electrical properties of InAsSb epilayers grown on GaAs(001)

    International Nuclear Information System (INIS)

    Jayavel, P.; Nakamura, S.; Koyama, T.; Hayakawa, Y.

    2006-01-01

    InAsSb ternary epilayers with arsenic composition of 0.5 have been grown on GaAs(001) substrates. Linear-graded and step-graded InAsSb buffer layers with an InSb layer have been used to relax lattice mismatch between the epilayer and substrate. X-ray diffraction results of the epilayers indicate that an enhancement in the peak intensity of the buffer layer samples is due to improved crystalline quality of the epilayers. We find that the growth technique of the buffer layer strongly influences the surface morphology and roughness of the epilayer. Hall effect measurements of the step-graded buffer layer samples show an order of magnitude higher electron mobility than the direct and linear-graded buffer layer samples. These results demonstrate that high crystalline quality and electron mobility of the InAs 0.5 Sb 0.5 ternary epilayers can be achieved by using the step-graded InAsSb buffer layers. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Improvement in surface morphology of GaSb buffer layer by two-step high and low temperature growth

    Science.gov (United States)

    Okumura, Shigekazu; Tomabechi, Shuichi; Suzuki, Ryo; Matsukura, Yusuke; Tsunoda, Koji; Kon, Jun-ichi; Nishino, Hironori

    2017-11-01

    The surface morphology of GaSb was investigated by changing growth conditions such as thermal oxide desorption temperature, growth temperature, and growth step by solid source molecular beam epitaxy. At high temperature growth, the pits caused by the thermal oxide desorption remained in the GaSb buffer layer surface, while the surface was sufficiently flattened. At low temperature growth, the pits disappeared, while the surface was not enough flattened even in the case of step-flow mode growth. Since the pits disappeared at lower growth temperature regardless of the growth mode, this behavior might be explained by the Ga migration length depending on the growth temperature. By applying two-step high/low temperature growth, where both growth steps proceed in step-flow mode, flat, a pit-free GaSb buffer surface could be obtained.

  18. Glycine buffered synthesis of layered iron(II)-iron(III) hydroxides (green rusts)

    DEFF Research Database (Denmark)

    Yin, Weizhao; Huang, Lizhi; Pedersen, Emil Bjerglund

    2017-01-01

    H fluctuations during base addition and hence allows for fast GRSO4 precipitation, minimizing byproduct formation. The use of other pH buffers [4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid and 2-amino-2-(hydroxymethyl)-1,3-propanediol] was also tested but failed. Mössbauer spectroscopy, X-ray diffraction...

  19. A possibility of enhancing Jc in MgB2 film grown on metallic hastelloy tape with the use of SiC buffer layer

    International Nuclear Information System (INIS)

    Putri, W. B. K.; Kang, B.; Ranot, M.; Lee, J. H.; Kang, W. N.

    2014-01-01

    We have grown MgB 2 on SiC buffer layer by using metallic Hastelloy tape as the substrate. Hastelloy tape was chosen for its potential practical applications, mainly in the power cable industry. SiC buffer layers were deposited on Hastelloy tapes at 400, 500, and 600 degrees C by using a pulsed laser deposition method, and then by using a hybrid physical-chemical vapor deposition technique, MgB 2 films were grown on the three different SiC buffer layers. An enhancement of critical current density values were noticed in the MgB 2 films on SiC/Hastelloy deposited at 500 and 600 degrees C. From the surface analysis, smaller and denser grains of MgB 2 tapes are likely to cause this enhancement. This result infers that the addition of SiC buffer layers may contribute to the improvement of superconducting properties of MgB 2 tapes.

  20. High quality InAsSb grown on InP substrates using AlSb/AlAsSb buffer layers

    International Nuclear Information System (INIS)

    Wu, B.-R.; Liao, C.; Cheng, K. Y.

    2008-01-01

    High quality InAsSb grown on semi-insulating InP substrates by molecular beam epitaxy was achieved using AlSb/AlAsSb structure as the buffer layer. A 1000 A InAsSb layer grown on top of 1 μm AlSb/AlAsSb buffer layer showed a room temperature electron mobility of ∼12 000 cm 2 /V s. High structural quality and low misfit defect density were also demonstrated in the InAsSb layer. This novel AlSb/AlAsSb buffer layer structure with the AlAsSb layer lattice matched to InP substrates could enhance the performance of optoelectronic devices utilizing 6.1 A family of compound semiconductor alloys

  1. Anomalous Hall effect suppression in anatase Co:TiO2 by the insertion of an interfacial TiO2 buffer layer

    NARCIS (Netherlands)

    Lee, Y.J.; de Jong, Machiel Pieter; van der Wiel, Wilfred Gerard; Kim, Y.; Brock, J.D.

    2010-01-01

    We present the effect of introducing a TiO2 buffer layer at the SrTiO3 /Co:TiO2 interface on the magnetic and structural properties of anatase Co:TiO2 1.4 at. % Co. Inserting the buffer layer leads to suppression of the room-temperature anomalous Hall effect, accompanied by a reduced density of Co

  2. Layer-by-layer assembled graphene-coated mesoporous SnO2 spheres as anodes for advanced Li-ion batteries

    KAUST Repository

    Shahid, Muhammad

    2014-10-01

    We report layer-by-layer (LBL) assembly of graphene/carbon-coated mesoporous SnO2 spheres (Gr/C-SnO2 spheres), without binder and conducting additives, as anode materials with excellent Li-ion insertion-extraction properties. Our results indicate that these novel LBL assembled electrodes have high reversible Li storage capacity, improved cycling, and especially good rate performance, even at high specific currents. The superior electrochemical performance offered by these LBL assembled Gr/C-SnO2 spheres is attributed to the enhanced electronic conductivity and effective diffusion of Li ions in the interconnected network of nanoparticles forming the mesoporous SnO2 spheres. © 2014 Elsevier B.V. All rights reserved.

  3. Chitosan-assisted buffer layer incorporated with hydroxypropyl methylcellulose-coated silver nanowires for paper-based sensors

    Science.gov (United States)

    Xu, Duohua; Qiu, Jingshen; Wang, Yucheng; Yan, Jiajun; Liu, Gui-Shi; Yang, Bo-Ru

    2017-06-01

    Fabricating flexible sensors on paper is intriguing. Here, we exploited chitosan as a buffer layer to facilitate the fabrication of silver nanowire (AgNW) networks and flexible devices on commercial paper. We found that the AgNW networks exhibited uniform distribution, smooth surface, and strong adhesion. The enhanced adhesion of AgNWs was attributed to the intermolecular hydrogen bonding between chitosan and hydroxypropyl methylcellulose (HPMC), which can be tailored by tuning the pH of the chitosan aqueous solution. This facile fabrication method utilizing biodegradable polymers and cost-effective AgNW ink holds great promise for portable, wearable, and disposable paper-based electronics.

  4. Hierarchical rendering of trees from precomputed multi-layer z-buffers

    Energy Technology Data Exchange (ETDEWEB)

    Max, N. [California Univ., Davis, CA (United States)

    1996-02-01

    Chen and Williams show how precomputed z-buffer images from different fixed viewing positions can be reprojected to produce an image for a new viewpoint. Here images are precomputed for twigs and branches at various levels in the hierarchical structure of a tree, and adaptively combined, depending on the position of the new viewpoint. The precomputed images contain multiple z levels to avoid missing pixels in the reconstruction, subpixel masks for anti-aliasing, and colors and normals for shading after reprojection.

  5. Chemical-bath ZnO buffer layer for CuInS{sub 2} thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A.; Weber, M.; Scheer, R.; Lewerenz, H.J. [Hahn-Meitner-Institut, Abt. Grenzflaechen, Bereich Physikalische Chemie, Glienicker Strasse 100, D-14109 Berlin (Germany)

    1998-07-13

    ZnO buffer layers were grown by a chemical-bath deposition (CBD) in order to improve the interface quality in p-CuInS{sub 2} based solar cells, to improve the light transmission in the blue wavelength region, but also as an alternative to eliminate the toxic cadmium. The process consists of immersion of different substrates (glass, CIS) in a dilute solution of tetraamminezinc II, [Zn(NH{sub 2}){sub 4}]{sup 2+}, complex at 60-95C. During the growth process, a homogeneous growth mechanism which proceeds by the sedimentation of a mixture of ZnO and Zn(OH){sub 2} clusters formed in solution, competes with the heterogeneous growth mechanism. The mechanism consists of specific adsorption of a complex Zn(II) followed by a chemical reaction. The last process of growth results in thin, hard, adherent and specularly reflecting films. The characterization of the deposited CBD-ZnO layers was performed by X-ray diffraction (XRD), optical transmittance, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The as-deposited films on glass show hexagonal zincite structure with two preferred orientations (1 0 0) and (1 0 1). High optical transmittance up to 80% in the near-infrared and part of the visible region was observed. The low growth rate of the films on CIS suggests an atomic layer-by-layer growth process.The device parameters and performance are compared to heterojunction with a standard CdS buffer layer

  6. Effects of TiO{sub 2} buffer layer on the photoelectrochemical properties of TiO{sub 2} Nano rods grown by modified chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae-hyun; Ha, Jin-wook; Ryu, Hyukhyun [Inje University, Gimhae (Korea, Republic of); Lee, Won-Jae [Dong-Eui University, Busan (Korea, Republic of)

    2015-08-15

    In this study, we grew TiO{sub 2} nano rods on TiO{sub 2}-film buffered FTO substrate using modified chemical bath deposition (M-CBD). The TiO{sub 2} buffer layer was grown by spin coating method with different RPM (revolutions per minute) values and deposition cycles. We investigated the effects of the RPM values and the deposition cycles on the morphological, structural and photoelectrochemical properties of TiO{sub 2} nano rods. In this work, we have also found that the morphological and structural properties of TiO{sub 2} nano rods affected the photoelectrochemical properties of TiO{sub 2} nano rods. And the maximum photocurrent density of 0.34 mA/cm{sup 2} at 0.6V (vs.SCE) was obtained from the buffer layer deposition process condition of 4,000 RPM and two-times buffer layer depositions.

  7. Performance and Metastability of CdTe Solar Cells with a Te Back-Contact Buffer Layer

    Science.gov (United States)

    Moore, Andrew

    Thin-film CdTe photovoltaics are quickly maturing into a viable clean-energy solution through demonstration of competitive costs and performance stability with existing energy sources. Over the last half decade, CdTe solar technology has achieved major gains in performance; however, there are still aspects that can be improved to progress toward their theoretical maximum efficiency. Perhaps equally valuable as high photovoltaic efficiency and a low levelized cost of energy, is device reliability. Understanding the root causes for changes in performance is essential for accomplishing long-term stability. One area for potential performance enhancement is the back contact of the CdTe device. This research incorporated a thin-film Te-buffer layer into the contact structure, between the CdTe and contact metal. The device performance and characteristics of many different back contact configurations were rigorously studied. CdTe solar cells fabricated with the Te-buffer contact showed short-circuit current densities and open-circuit voltages that were on par with the traditional back-contacts used at CSU. However, the Te-buffer contact typically produced 2% larger fill-factors on average, leading to greater conversation efficiency. Furthermore, using the Te buffer allowed for incorporation of 50% less Cu, which is used for p-type doping but is also known to decrease lifetime and stability. This resulted in an additional 3% fill-factor gain with no change in other parameters compared to the standard-Cu treated device. In order to better understand the physical mechanisms of the Te-buffer contact, electrical and material properties of the Te layer were extracted and used to construct a simple energy band diagram. The Te layer was found to be highly p-type (>1018 cm-3) and possess a positive valence-band offset of 0.35-0.40 eV with CdTe. An existing simulation model incorporating the Te-layer properties was implemented and validated by comparing simulated results of Cd

  8. Enhanced performance of C60 organic field effect transistors using a tris(8-hydroxyquinoline) aluminum buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Zheng Hong; Cheng Xiaoman; Tian Haijun [Institute of Material Physics, Key Laboratory of Display Material and Photoelectric Devices, Ministry of Education, Tianjin University of Technology, Tianjin 300384 (China); Zhao Geng, E-mail: zheng_033@163.com [School of Science, Tianjin University of Technology, Tianjin 300384 (China)

    2011-09-15

    We have investigated the properties of C60-based organic field effect transistors (OFETs) with a tris(8-hydroxyquinoline) aluminum (Alq3) buffer layer inserted between the source/drain electrodes and the active material. The electrical characteristics of OFETs are improved with the insertion of Alq3 film. The peak field effect mobility is increased to 1.28 x 10{sup -2} cm{sup 2}/(V{center_dot}s) and the threshold voltage is decreased to 10 V when the thickness of the Alq3 is 10 nm. The reason for the improved performance of the devices is probably due to the prevention of metal atoms diffusing into the C60 active layer and the reduction of the channel resistance in Alq3 films. (semiconductor devices)

  9. Improving the Long-Term Stability of Perovskite Solar Cells with a Porous Al 2 O 3 Buffer Layer

    KAUST Repository

    Guarnera, Simone

    2015-02-05

    © 2015 American Chemical Society. Hybrid perovskites represent a new paradigm for photovoltaics, which have the potential to overcome the performance limits of current technologies and achieve low cost and high versatility. However, an efficiency drop is often observed within the first few hundred hours of device operation, which could become an important issue. Here, we demonstrate that the electrode\\'s metal migrating through the hole transporting material (HTM) layer and eventually contacting the perovskite is in part responsible for this early device degradation. We show that depositing the HTM within an insulating mesoporous "buffer layer" comprised of Al2O3 nanoparticles prevents the metal electrode migration while allowing for precise control of the HTM thickness. This enables an improvement in the solar cell fill factor and prevents degradation of the device after 350 h of operation. (Graph Presented).

  10. Development of mid-frequency AC reactive magnetron sputtering for fast deposition of Y2O3 buffer layers

    Science.gov (United States)

    Xiong, Jie; Xia, Yudong; Xue, Yan; Zhang, Fei; Guo, Pei; Zhao, Xiaohui; Tao, Bowan

    2014-02-01

    A reel-to-reel magnetron sputtering system with mid-frequency alternating current (AC) power supply was used to deposit double-sided Y2O3 seed layer on biaxially textured Ni-5 at.%W tape for YBa2Cu3O7-δ coated conductors. A reactive sputtering process was carried out using two opposite symmetrical sputtering guns with metallic yttrium targets and water vapor for oxidizing the sputtered metallic atoms. The voltage control mode of the power supply was used and the influence of the cathode voltage and ArH2 pressure were systematically investigated. Subsequently yttrium-stabilized zirconia (YSZ) barrier and CeO2 cap layers were deposited on the Y2O3 buffered substrates in sequence, indicating high quality and uniform double-sided structure and surface morphology of such the architecture.

  11. Improvement in crystallinity of apatite coating on titanium with the insertion of CaF2 buffer layer.

    Science.gov (United States)

    Lee, Su-Hee; Kim, Hyoun-Ee; Kim, Hae-Won

    2008-05-01

    In the apatite coatings on Ti the heat treatment process is necessary to crystallize the apatite structure for improved chemical stability and biological properties. However, the heat treatment normally degrades the mechanical strength of the coating layer associated with thermally induced stress. In this study, we aimed to improve the crystallization of apatite coating by using calcium fluoride (CaF2) as a buffer layer. The insertion of a thin layer of CaF2 (0.2-1 microm) between apatite and Ti significantly improved the crystallization behavior of apatite. Moreover, this crystallization was more enhanced as the thickness of CaF2 was increased. When a 1 microm-thick CaF2 was inserted, the crystallization of apatite initiated at a temperature as low as 320 degrees C, being a dramatic improvement in the crystallization when considering the crystallization initiation temperature of a bare apatite coating on Ti was approximately 450 degrees C. As a result of this crystallization enhancement, the dissolution behavior of CaF2-inserted apatite coatings was more stable than that of the bare apatite coating, showing much reduced initial-burst effect. Preliminary cellular assay showed the CaF2-inserted apatite coating provided a substrate for cells to spread and grow favorably, as being similar to the bare apatite coating. This novel way of apatite coating on Ti using CaF2 buffer layer may be useful in the coating systems particularly requiring low temperature processing and increased crystallinity with high chemical stability.

  12. Effects of Chain Orientation in Self-Organized Buffer Layers Based on Poly(3-alkylthiophene)s for Organic Photovoltaics.

    Science.gov (United States)

    Wang, Fanji; Hashimoto, Kazuhito; Segawa, Hiroshi; Tajima, Keisuke

    2018-03-14

    Surface-segregated monolayers (SSMs) based on two poly(3-alkylthiophene)s with semifluoroalkyl groups at either the side chains (P3DDFT) or one end of the main chain (P3BT-F 17 ) were used as self-organized buffer layers at the electrode interfaces in bulk heterojunction (BHJ) organic photovoltaic devices. Both of the SSMs greatly shifted the vacuum levels of the BHJ films at the surface due to the aligned permanent dipole moments of the semifluoroalkyl chains. Hole extraction in the BHJ of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C 61 -butyric acid methyl ester (PCBM) became more efficient in the presence of the P3DDFT buffer layer, resulting in an improved power conversion efficiency. In contrast, the SSM of P3BT-F 17 induced changes in the chain orientation of P3HT and the morphology of the BHJ films, resulting in decreased performance. These results indicate that the molecular design of polymer-based SSMs can affect not only the energy structure at the interface but also the morphology and the molecular orientations in the BHJs.

  13. Post-mortem analysis on LiFePO4|Graphite cells describing the evolution & composition of covering layer on anode and their impact on cell performance

    Science.gov (United States)

    Lewerenz, Meinert; Warnecke, Alexander; Sauer, Dirk Uwe

    2017-11-01

    During cyclic aging of lithium-ion batteries the formation of a μm-thick covering layer on top of the anode facing the separator is found on top of the anode. In this work several post-mortem analyses of cyclic aged cylindrical LFP|Graphite cells are evaluated to give a detailed characterization of the covering layer and to find possible causes for the evolution of such a layer. The analyses of the layer with different methods return that it consists to high percentage of plated active lithium, deposited Fe and products of a solid electrolyte interphase (SEI). The deposition is located mainly in the center of the cell symmetrical to the coating direction. The origin of these depositions is assumed in locally overcharged particles, Fe deposition or inhomogeneous distribution of capacity density. As a secondary effect the deposition on one side increases the thickness locally; thereafter a pressure-induced overcharging due to charge agglomeration of the back side of the anode occurs. Finally a compact and dense covering layer in a late state of aging leads to deactivation of the covered parts of the anode and cathode due to suppressed lithium-ion conductivity. This leads to increasing slope of capacity fade and increase of internal resistance.

  14. Effect of thermal annealing treatment with titanium chelate on buffer layer in inverted polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhiyong [College of Science, Shenyang Agricultural University, Shenyang 110866 (China); Wang, Ning, E-mail: ning_wang@outlook.com [School of Electrical and Electronic and Engineering, Nanyang Technological University 639798 (Singapore); Fu, Yan, E-mail: 1060945062@qq.com [College of Science, Shenyang Agricultural University, Shenyang 110866 (China)

    2016-12-15

    Highlights: • The TIPD layer as electron extraction layer and instead of Ca or LiF. • Impact of the work function of TIPD layer by thermal annealing treatment. • Importance of TIPD layer as electron extraction layer for work function and potential barrier. - Abstract: The solution processable electron extraction layer (EEL) is crucial for polymer solar cells (PSCs). Here, we investigated titanium (diisopropoxide) bis(2,4-pentanedionate) (TIPD) as an EEL and fabricated inverted PSCs with a blend of poly(3-hexylthiophene) (P3HT) and indene-C60 bisadduct (ICBA) acting as the photoactive layer, with a structure of ITO/TIPD/P3HT:ICBA/MoO{sub 3}/Ag. After thermal annealing treatment at 150 °C for 15 min, the PSC performances increased from 3.85% to 6.84% and they achieve stable power conversion efficiency (PCE), with a similar PCE compared with TiO{sub 2} as an EEL by the vacuum evaporated method. Fourier transform infrared spectroscopy (FTIR) and ultraviolet photoelectron spectroscopy (UPS) confirmed that the TIPD decomposed and formed the Ti=O bond, and the energy level of the lowest unoccupied molecular orbital and the highest occupied molecular orbital increased. The space charge limited current (SCLC) measurements further confirmed the improvement in electron collection and the transport ability using TIPD as the EEL and thermal annealing.

  15. Effect of thermal annealing treatment with titanium chelate on buffer layer in inverted polymer solar cells

    International Nuclear Information System (INIS)

    Liu, Zhiyong; Wang, Ning; Fu, Yan

    2016-01-01

    Highlights: • The TIPD layer as electron extraction layer and instead of Ca or LiF. • Impact of the work function of TIPD layer by thermal annealing treatment. • Importance of TIPD layer as electron extraction layer for work function and potential barrier. - Abstract: The solution processable electron extraction layer (EEL) is crucial for polymer solar cells (PSCs). Here, we investigated titanium (diisopropoxide) bis(2,4-pentanedionate) (TIPD) as an EEL and fabricated inverted PSCs with a blend of poly(3-hexylthiophene) (P3HT) and indene-C60 bisadduct (ICBA) acting as the photoactive layer, with a structure of ITO/TIPD/P3HT:ICBA/MoO 3 /Ag. After thermal annealing treatment at 150 °C for 15 min, the PSC performances increased from 3.85% to 6.84% and they achieve stable power conversion efficiency (PCE), with a similar PCE compared with TiO 2 as an EEL by the vacuum evaporated method. Fourier transform infrared spectroscopy (FTIR) and ultraviolet photoelectron spectroscopy (UPS) confirmed that the TIPD decomposed and formed the Ti=O bond, and the energy level of the lowest unoccupied molecular orbital and the highest occupied molecular orbital increased. The space charge limited current (SCLC) measurements further confirmed the improvement in electron collection and the transport ability using TIPD as the EEL and thermal annealing.

  16. Device performance and lifetime of polymer:fullerene solar cells with UV-ozone-irradiated hole-collecting buffer layers.

    Science.gov (United States)

    Lee, Seungsoo; Nam, Sungho; Lee, Hyena; Kim, Hwajeong; Kim, Youngkyoo

    2011-11-18

    We report the influence of UV-ozone irradiation of the hole-collecting buffer layers on the performance and lifetime of polymer:fullerene solar cells. UV-ozone irradiation was targeted at the surface of the poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) layers by varying the irradiation time up to 600 s. The change of the surface characteristics in the PEDOT:PSS after UV-ozone irradiation was measured by employing optical absorption spectroscopy, photoelectron yield spectroscopy, and contact angle measurements, while Raman and X-ray photoelectron spectroscopy techniques were introduced for more microscopic analysis. Results showed that the UV-ozone irradiation changed the chemical structure/composition of the surface of the PEDOT:PSS layers leading to the gradual increase of ionization potential with irradiation time in the presence of up-and-down variations in the contact angle (polarity). This surface property change was attributed to the formation of oxidative components, as evidenced by XPS and Auger electron images, which affected the sheet resistance of the PEDOT:PSS layers. Interestingly, device performance was slightly improved by short irradiation (up to 10 s), whereas it was gradually decreased by further irradiation. The short-duration illumination test showed that the lifetime of solar cells with the UV-ozone irradiated PEDOT:PSS layer was improved due to the protective role of the oxidative components formed upon UV-ozone irradiation against the attack of sulfonic acid groups in the PEDOT:PSS layer to the active layer. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Atmospheric spatial atomic-layer-deposition of Zn(O, S) buffer layer for flexible Cu(In, Ga)Se2 solar cells: From lab-scale to large area roll to roll processing

    NARCIS (Netherlands)

    Frijters, C.H.; Bolt, P.J.; Poodt, P.W.G.; Knaapen, R.; Brink, J. van den; Ruth, M.; Bremaud, D.; Illiberi, A.

    2016-01-01

    In this manuscript we present the first successful application of a spatial atomic-layer-deposition process to thin film solar cells. Zn(O,S) has been grown by spatial atomic layer deposition (S-ALD) at atmospheric pressure and applied as buffer layer in rigid and flexible CIGS cells by a lab-scale

  18. Facile synthesis of Ni-decorated multi-layers graphene sheets as effective anode for direct urea fuel cells

    Directory of Open Access Journals (Sweden)

    Ahmed Yousef

    2017-09-01

    Full Text Available A large amount of urea-containing wastewater is produced as a by-product in the fertilizer industry, requiring costly and complicated treatment strategies. Considering that urea can be exploited as fuel, this wastewater can be treated and simultaneously exploited as a renewable energy source in a direct urea fuel cell. In this study, multi-layers graphene/nickel nanocomposites were prepared by a one-step green method for use as an anode in the direct urea fuel cell. Typically, commercial sugar was mixed with nickel(II acetate tetrahydrate in distilled water and then calcined at 800 °C for 1 h. Raman spectroscopy, X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM and energy dispersive spectroscopy (EDS were employed to characterize the final product. The results confirmed the formation of multi-layers graphene sheets decorated by nickel nanoparticles. To investigate the influence of metal nanoparticles content, samples were prepared using different amounts of the metal precursor; nickel acetate content was changed from 0 to 5 wt.%. Investigation of the electrochemical characterizations indicated that the sample prepared using the original solution with 3 wt.% nickel acetate had the best current density, 81.65 mA/cm2 in a 0.33 M urea solution (in 1 M KOH at an applied voltage 0.9 V vs Ag/AgCl. In a passive direct urea fuel cell based on the optimal composition, the observed maximum power density was 4.06 × 10−3 mW/cm2 with an open circuit voltage of 0.197 V at room temperature in an actual electric circuit. Overall, this study introduces a cheap and beneficial methodology to prepare effective anode materials for direct urea fuel cells.

  19. Structure and magnetic properties of NdFeB thin films with Cr, Mo, Nb, Ta, Ti, and V buffer layers

    International Nuclear Information System (INIS)

    Jiang, H.; O'Shea, M.J.

    2000-01-01

    Layers of NdFeB of the form A(20 nm)/NdFeB(d nm)/A(20 nm) where A represents Cr, Mo, Nb, Ta, Ti, V were prepared on a silicon substrate by magnetron sputtering. The purpose is to determine how (i) the chosen buffer layer and (ii) NdFeB layer thickness d (especially d 2 Fe 14 B with no preferred crystalline orientation. Our highest coercivities occur for buffer layer elements from row five of the periodic table, 20 kOe (1600 kA/m) in a Nb buffered sample with d of 180 nm and 17 kOe (1350 kA/m) in a Mo buffered sample with d of 180 nm. Buffer layers from row four (Ti, V, and Cr) and row six (Ta) all give lower coercivities. Our largest energy product, 10.3 MG-Oe (82 kJ/m 3 ), is obtained for the Mo buffered sample. Average Nd 2 Fe 14 B crystallite size for this sample is 27 nm. Only the Cr and Ti buffered films show a large coercivity (≥2 kOe) for d of 54 nm with the Cr films showing the highest coercivity, 2.7 kOe (215 kA/m). In films subjected to a rapid thermal anneal (anneal time 30 s) we find that both the coercivity and energy product are larger than in samples subjected to a 20 min anneal. In our Nb buffered systems we obtain coercivities as high as 26.3 kOe (2090 kA/m) after a rapid thermal anneal

  20. Physical properties and interface studies of YBa2Cu3O7 thin films deposited by laser ablation on S1 (111) with buffer layer

    NARCIS (Netherlands)

    Blank, David H.A.; Aarnink, W.A.M.; Aarnink, W.A.M.; Flokstra, Jakob; Rogalla, Horst; van Silfhout, Arend

    1990-01-01

    The physical properties of laser-deposited YBaCuO on Si using a single buffer layer of ZrO2 and a double layer of NiSi2 and ZrO2 have been studied. The influence of the deposition temperature has been investigated. Interface studies were performed by RBS and SAM. SEM pictures, resistivity and

  1. Optical properties of Pb (Zr0.52Ti0.48) O3/BiFeO3 multilayers with ZnO buffer layer

    Science.gov (United States)

    Dutta, Shankar; Pandey, Akhilesh; Jindal, Kajal; Thakur, O. P.; Gupta, Vinay; Chatterjee, Ratnamala

    2015-07-01

    This paper discussed about the optical properties of the PZT-BFO multilayer thin films, deposited with or without ZnO buffer layer. The elemental distribution of the PZT and BFO layers is found to vary across the thickness of the multilayer films. Raman spectroscopy measurement of both the multilayers samples has showed no sharp peaks due to the polycrystalline nature of the films and partial overlap of the Raman peaks of individual PZT and BFO layers. Photoluminescence study of the buffered film showed peaks at 400, 525, and 580 nm, whereas the un-buffered film showed PL peaks at 405 and 530 nm. The peak at 580 nm appears to be due to the ZnO buffer layer. The ZnO-buffered thin film shows more intense Raman and photoluminescence peaks compared with the thin film with no buffer. The absorption spectra of the PZT-BFO multilayers under the mid-IR radiations showed a sharp peak at 690 cm-1 in both the samples. It might be due to the structural rearrangement of the BO6 and AO12 units resulting in perovskite phase (ABO3) formation.

  2. Molecular beam epitaxy of GaSb on GaAs substrates with AlSb/GaSb compound buffer layers

    International Nuclear Information System (INIS)

    Hao Ruiting; Deng Shukang; Shen Lanxian; Yang Peizhi; Tu Jielei; Liao Hua; Xu Yingqiang; Niu Zhichuan

    2010-01-01

    GaSb films with AlSb/GaSb compound buffer layers were grown by molecular beam epitaxy on GaAs (001) substrates. The crystal quality and optical properties were studied by high resolution transition electron microscopy and low temperature photoluminescence spectra (PL), respectively. It was found that the AlSb/GaSb compound buffer layers can restrict the dislocations into GaSb epilayers. The intensity of PL spectra of GaSb layer becomes large with the increasing the periods of AlSb/GaSb superlattices, indicating that the optical quality of GaSb films is improved.

  3. Environmental Modeling, The Buffer Priority layers for Nitrogen Removal identify priority forest/grass buffer sites by subwatershed. Land use, hydrology, soil, and landscape characteristics were analyzed to rank opportunities with high nitrogen removal potential., Published in 2014, Smaller than 1:100000 scale, Maryland Department of Natural Resources (DNR).

    Data.gov (United States)

    NSGIC Education | GIS Inventory — Environmental Modeling dataset current as of 2014. The Buffer Priority layers for Nitrogen Removal identify priority forest/grass buffer sites by subwatershed. Land...

  4. Physical-Layer Security of a Buffer-Aided Full-Duplex Relaying System

    KAUST Repository

    El Shafie, Ahmed

    2016-07-07

    This letter proposes a novel hybrid half-/full-duplex relaying scheme to enhance the relay channel security. A source node (Alice) communicates with her destination node (Bob) in the presence of a buffer-aided full-duplex relay node (Rooney) and a potential eavesdropper (Eve). Rooney adopts two different relaying, namely randomize-and-forward and decode-andforward relaying strategies, to improve the security of the legitimate system. In the first relaying strategy, Rooney uses a codebook different from that used at Alice. In the second relaying strategy, Rooney and Alice use the same codebooks. In addition, Rooney switches between half-duplex and full-duplex modes to further enhance the security of the legitimate system. The numerical results demonstrate that our proposed scheme achieves a significant average secrecy end-to-end throughput improvement relative to the conventional bufferless full-duplex relaying scheme.

  5. Synthesis and characterization of (Cd,Zn)S buffer layer for Cu2ZnSnSe4 solar cells

    Science.gov (United States)

    Ben Messaoud, Khaled; Buffière, Marie; Brammertz, Guy; Lenaers, Nick; Boyen, Hans-Gerd; Sahayaraj, Sylvester; Meuris, Marc; Amlouk, Mosbah; Poortmans, Jef

    2017-07-01

    In order to improve the electrical performances of Cu2ZnSnSe4 (CZTSe) based solar cells, the standard CdS buffer layer was replaced by (Cd,Zn)S processed by chemical bath deposition. The morphology and composition of the (Cd,Zn)S thin films were studied as a function of [Zn]/([Zn]  +  [Cd]) ratio in the chemical bath (80, 85 and 90%). The CZTSe/(Cd,Zn)S solar cells with and without Cd partial electrolyte (Cd PE) treatment were compared to CZTSe/CdS reference devices using current-voltage and external quantum efficiency measurements. The (Cd,Zn)S thin films show a non-homogeneity of Zn distribution and phase formation, with a shift from Zn(O,OH) x to ZnS phase when increasing the deposition time and a decrease of the layers thicknesses when increasing the Zn concentration in chemical bath. A model for the growth of (Cd,Zn)S thin films is proposed. The resulting CZTSe/(Cd,Zn)S devices show an important reduction of the barrier at the hetero-interface, which is attributed to the lower density of O contamination in (Cd,Zn)S compared to CdS, inducing a lower density of deep p-type recombination centers. Despite the reduced compensation of the buffer layer, CZTSe/(Cd,Zn)S devices show a deterioration of the open circuit voltage and the fill factor with the increase of Zn content in (Cd,Zn)S. These electrical losses were avoided by Cd PE treatment prior to the deposition of (Cd,Zn)S.

  6. Self-assembled, aligned ZnO nanorod buffer layers for high-current-density, inverted organic photovoltaics.

    Science.gov (United States)

    Rao, Arun D; Karalatti, Suresh; Thomas, Tiju; Ramamurthy, Praveen C

    2014-10-08

    Two different soft-chemical, self-assembly-based solution approaches are employed to grow zinc oxide (ZnO) nanorods with controlled texture. The methods used involve seeding and growth on a substrate. Nanorods with various aspect ratios (1-5) and diameters (15-65 nm) are grown. Obtaining highly oriented rods is determined by the way the substrate is mounted within the chemical bath. Furthermore, a preheat and centrifugation step is essential for the optimization of the growth solution. In the best samples, we obtain ZnO nanorods that are almost entirely oriented in the (002) direction; this is desirable since electron mobility of ZnO is highest along this crystallographic axis. When used as the buffer layer of inverted organic photovoltaics (I-OPVs), these one-dimensional (1D) nanostructures offer: (a) direct paths for charge transport and (b) high interfacial area for electron collection. The morphological, structural, and optical properties of ZnO nanorods are studied using scanning electron microscopy, X-ray diffraction, and ultraviolet-visible light (UV-vis) absorption spectroscopy. Furthermore, the surface chemical features of ZnO films are studied using X-ray photoelectron spectroscopy and contact angle measurements. Using as-grown ZnO, inverted OPVs are fabricated and characterized. For improving device performance, the ZnO nanorods are subjected to UV-ozone irradiation. UV-ozone treated ZnO nanorods show: (i) improvement in optical transmission, (ii) increased wetting of active organic components, and (iii) increased concentration of Zn-O surface bonds. These observations correlate well with improved device performance. The devices fabricated using these optimized buffer layers have an efficiency of ∼3.2% and a fill factor of 0.50; this is comparable to the best I-OPVs reported that use a P3HT-PCBM active layer.

  7. Surface Passivation of MoO₃ Nanorods by Atomic Layer Deposition toward High Rate Durable Li Ion Battery Anodes.

    Science.gov (United States)

    Ahmed, B; Shahid, Muhammad; Nagaraju, D H; Anjum, D H; Hedhili, Mohamed N; Alshareef, H N

    2015-06-24

    We demonstrate an effective strategy to overcome the degradation of MoO3 nanorod anodes in lithium (Li) ion batteries at high-rate cycling. This is achieved by conformal nanoscale surface passivation of the MoO3 nanorods by HfO2 using atomic layer deposition (ALD). At high current density such as 1500 mA/g, the specific capacity of HfO2-coated MoO3 electrodes is 68% higher than that of bare MoO3 electrodes after 50 charge/discharge cycles. After 50 charge/discharge cycles, HfO2-coated MoO3 electrodes exhibited specific capacity of 657 mAh/g; on the other hand, bare MoO3 showed only 460 mAh/g. Furthermore, we observed that HfO2-coated MoO3 electrodes tend to stabilize faster than bare MoO3 electrodes because nanoscale HfO2 layer prevents structural degradation of MoO3 nanorods. Additionally, the growth temperature of MoO3 nanorods and the effect of HfO2 layer thickness was studied and found to be important parameters for optimum battery performance. The growth temperature defines the microstructural features and HfO2 layer thickness defines the diffusion coefficient of Li-ions through the passivation layer to the active material. Furthermore, ex situ high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction were carried out to explain the capacity retention mechanism after HfO2 coating.

  8. Surface Passivation of MoO3 Nanorods by Atomic Layer Deposition Towards High Rate Durable Li Ion Battery Anodes

    KAUST Repository

    Ahmed, Bilal

    2015-06-03

    We demonstrate an effective strategy to overcome the degradation of MoO3 nanorod anodes in Lithium (Li) ion batteries at high rate cycling. This is achieved by conformal nanoscale surface passivation of the MoO3 nanorods by HfO2 using atomic layer deposition (ALD). At high current density such as 1500 mA/g, the specific capacity of HfO2 coated MoO3 electrodes is 68% higher than bare MoO3 electrodes after 50 charge/discharge cycles. After 50 charge/discharge cycles, HfO2 coated MoO3 electrodes exhibited specific capacity of 657 mAh/g, on the other hand, bare MoO3 showed only 460 mAh/g. Furthermore, we observed that HfO2 coated MoO3 electrodes tend to stabilize faster than bare MoO3 electrodes because nanoscale HfO2 layer prevents structural degradation of MoO3 nanorods. Additionally, the growth temperature of MoO3 nanorods and the effect of HfO2 layer thickness was studied and found to be important parameters for optimum battery performance. The growth temperature defines the microstructural features and HfO2 layer thickness defines the diffusion coefficient of Li–ions through the passivation layer to the active material. Furthermore, ex–situ HRTEM, X–ray photoelectron spectroscopy (XPS), Raman spectroscopy and X–ray diffraction was carried out to explain the capacity retention mechanism after HfO2 coating.

  9. Fabrication of supported Ca-doped lanthanum niobate electrolyte layer and NiO containing anode functional layer by electrophoretic deposition

    DEFF Research Database (Denmark)

    Bozza, Francesco; Bonanos, Nikolaos

    2012-01-01

    The technique of electrophoretic deposition (EPD) has been applied for the preparation of a dense calcium-doped lanthanum niobate electrolyte film. La0.995Ca0.005NbO4 (LCN) powder was suspended in a solution of acetylacetone, iodine and water. The effects of suspension composition and deposition...... conditions were analyzed in order to identify a suitable set of EPD process parameters. The powders were deposited on a composite substrate of LCN, NiO, binder and graphite. A dense 8 μm film of lanthanum niobate supported on a porous substrate was obtained after sintering at 1200 °C. The technique was found...... to be effective also for the deposition of a mixture of NiO and LCN powders which, after sintering, would form LCN/NiO anode functional layer. Electrochemical characterization of the supported LCN film was performed by applying a LCN/NiO counter electrode....

  10. High performance organic photovoltaics with zinc oxide and graphene oxide buffer layers

    Science.gov (United States)

    Mohd Yusoff, Abd Rashid Bin; Kim, Hyeong Pil; Jang, Jin

    2014-01-01

    We report air stable inverted organic photovoltaics (OPVs) incorporating graphene oxide (GO) and solution processed zinc oxide (ZnO) as hole transport and electron transport layers, respectively. Both the hole transport layer and the electron transport layer (HTL and ETL) are of advantage in high transparency and environmental stability. The use of GO and ZnO in poly(2,7-carbazole) derivative (PCDTBT):fullerene derivative (PC70BM)-based inverted OPVs leads to an improved device stability and enhanced high open circuit voltage (Voc) of 0.81 V, a short-circuit current density (Jsc) of 14.10 mA cm-2, and a fill factor (FF) of 54.44 along with a power conversion efficiency of 6.20%.

  11. Development of Production PVD-AIN Buffer Layer System and Processes to Reduce Epitaxy Costs and Increase LED Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Cerio, Frank

    2013-09-14

    The DOE has set aggressive goals for solid state lighting (SSL) adoption, which require manufacturing and quality improvements for virtually all process steps leading to an LED luminaire product. The goals pertinent to this proposed project are to reduce the cost and improve the quality of the epitaxial growth processes used to build LED structures. The objectives outlined in this proposal focus on achieving cost reduction and performance improvements over state-of-the-art, using technologies that are low in cost and amenable to high efficiency manufacturing. The objectives of the outlined proposal focus on cost reductions in epitaxial growth by reducing epitaxy layer thickness and hetero-epitaxial strain, and by enabling the use of larger, less expensive silicon substrates and would be accomplished through the introduction of a high productivity reactive sputtering system and an effective sputtered aluminum-nitride (AlN) buffer/nucleation layer process. Success of the proposed project could enable efficient adoption of GaN on-silicon (GaN/Si) epitaxial technology on 150mm silicon substrates. The reduction in epitaxy cost per cm{sup 2} using 150mm GaN-on-Si technology derives from (1) a reduction in cost of ownership and increase in throughput for the buffer deposition process via the elimination of MOCVD buffer layers and other throughput and CoO enhancements, (2) improvement in brightness through reductions in defect density, (3) reduction in substrate cost through the replacement of sapphire with silicon, and (4) reduction in non-ESD yield loss through reductions in wafer bow and temperature variation. The adoption of 150mm GaN/Si processing will also facilitate significant cost reductions in subsequent wafer fabrication manufacturing costs. There were three phases to this project. These three phases overlap in order to aggressively facilitate a commercially available production GaN/Si capability. In Phase I of the project, the repeatability of the performance

  12. Influence of bicarbonate ions on the stability of prepassive layers formed on copper in carbonate-bicarbonate buffers

    Energy Technology Data Exchange (ETDEWEB)

    Ribotta, S.B.; Folquer, M.E. [Universidad Nacional de Tucuman (Argentina). Instituto de Quimica Fisica; Vilche, J.R. [Universidad Nacional de La Plate (Argentina). Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas

    1995-09-01

    The dissolution and passivation of polycrystalline copper (Cu) electrodes in carbonate (CO{sub 3}{sup 2{minus}})-bicarbonate (HCO{sub 3}{sup {minus}}) solutions covering wide ranges of pH and electrolyte compositions were studied at 25 C. The influences of the CO{sub 3}{sup 2{minus}}-HCO{sub 3}{sup {minus}} concentration ratio and hydrodynamic conditions on electrodissolution of the base metal, on formation of prepassivating and passivating surface layers, and on chemical dissolution of the prepassive films were considered. Results obtained with a rotating disc electrode allowed the competing reactions related to the active-to-passive transition to be distinguished through the effects of potential scan rate and electrode rotation speed on the electrochemical behavior of the system at fixed concentrations of CO{sub 3}{sup 2{minus}} or HCO{sub 3}{sup {minus}}. Data were discussed on the basis of the interactions between HCO{sub 3}{sup {minus}} and Cu(II) oxide and hydroxide anodic products in the prepassive surface layer.

  13. Development and application of a green-chemistry solution deposition technique for buffer layer coating on cube-textured metal substrates in view of further deposition of rare-earth based superconductors

    DEFF Research Database (Denmark)

    Pallewatta, Pallewatta G A P

    which consist of YBCO superconducting coatings on cube-textured Ni based alloy tapes.  Before the epitaxial deposition this superconducting layer, a buffer layer is applied on the metal substrate as a diffusion barrier which is also required to transfer the strong texture of the underlying substrate......, allowing the epitaxial growth of the superconducting layer. State-of-the-art coated conductor hetero structures are mainly based on CeO2 based buffer stacks that consist of a sequence of several different buffer layers. Buffer layers deposited by continuous chemical deposition techniques, which...... are the most suitable for large scale production, use to suffer from porosity and cracks that lead to material diffusion from the metal substrate into the superconductor as well as oxidation of the metal during high-temperature processing of the buffer layer. SrTiO3 buffer layers have attracted interest due...

  14. High-resolution synchrotron diffraction study of porous buffer InP(001) layers

    Czech Academy of Sciences Publication Activity Database

    Lomov, A. A.; Punegov, V. I.; Nohavica, Dušan; Chuev, M.A.; Vasiliev, A.L.; Novikov, D. V.

    Roč. 47, č. 5 ( 2014 ), s. 1614-1625 ISSN 0021-8898 Institutional support: RVO:67985882 Keywords : porous layers * X-ray reciprocal space mapping * indium phosphide Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.720, year: 2014

  15. Evaluation of methods for application of epitaxial buffer and superconductor layers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-30

    The recent achievements of critical currents exceeding million amperes per square centimeter at 77K in YBCO deposited over suitably textured substrate have stimulated interest in the potential applications of coated conductors at high temperatures and in high magnetic fields. Currently, ion-beam assisted deposition (IBAD), and rolling assisted bi-axially textured substrate (RABiTS), represent two available options for obtaining textured substrates. For applying suitable coatings of buffer and high temperature superconductor (HTS) material over textured substrates, several options are available which include sputtering, electron-beam evaporation, laser ablation, electrophoresis, chemical vapor deposition (including metal organics chemical vapor deposition), sol-gel, metal organics decomposition, electrodeposition and aerosol/spray pyrolysis. A commercial continuous long-length wire/tape manufacturing scheme developed out of any suitable combination of the above techniques would consist of operations involving preparation of the substrate and application of buffer, HTS and passivation/insulation materials and special treatment steps such as post-annealing. These operations can be effected by various process parameters that can be classified into chemistry, materials, engineering and environmental related parameters. Under the DOE-sponsored program, to carry out an engineering evaluation, first, the process flow schemes were developed for various candidate options identifying the major operating steps, process conditions, and process streams. Next, to evaluate quantifiable parameters such as process severity (e.g. temperature and pressure), coating thickness and deposition rate for HTS material, achieved maximum J{sub c} value (for films >1{micro}m thick) and cost of chemical and material utilization efficiency, the multi-attribute method was used to determine attributes/merits for various parameters and candidate options. To determine similar attribute values for the

  16. Reduced interface recombination in Cu2ZnSnS4 solar cells with atomic layer deposition Zn1-xSnxOy buffer layers

    Science.gov (United States)

    Platzer-Björkman, C.; Frisk, C.; Larsen, J. K.; Ericson, T.; Li, S.-Y.; Scragg, J. J. S.; Keller, J.; Larsson, F.; Törndahl, T.

    2015-12-01

    Cu2ZnSnS4 (CZTS) solar cells typically include a CdS buffer layer in between the CZTS and ZnO front contact. For sulfide CZTS, with a bandgap around 1.5 eV, the band alignment between CZTS and CdS is not ideal ("cliff-like"), which enhances interface recombination. In this work, we show how a Zn1-xSnxOy (ZTO) buffer layer can replace CdS, resulting in improved open circuit voltages (Voc) for CZTS devices. The ZTO is deposited by atomic layer deposition (ALD), with a process previously developed for Cu(In,Ga)Se2 solar cells. By varying the ALD process temperature, the position of the conduction band minimum of the ZTO is varied in relation to that of CZTS. A ZTO process at 95 °C is found to give higher Voc and efficiency as compared with the CdS reference devices. For a ZTO process at 120 °C, where the conduction band alignment is expected to be the same as for CdS, the Voc and efficiency is similar to the CdS reference. Further increase in conduction band minimum by lowering the deposition temperature to 80 °C shows blocking of forward current and reduced fill factor, consistent with barrier formation at the junction. Temperature-dependent current voltage analysis gives an activation energy for recombination of 1.36 eV for the best ZTO device compared with 0.98 eV for CdS. We argue that the Voc of the best ZTO devices is limited by bulk recombination, in agreement with a room temperature photoluminescence peak at around 1.3 eV for both devices, while the CdS device is limited by interface recombination.

  17. Metallic MoN layer and its application as anode for lithium-ion batteries

    Science.gov (United States)

    Zhang, Qiaoxuan; Ma, Jiachen; Lei, Ming; Quhe, Ruge

    2018-04-01

    Recently, two-dimensional (2D) metallic MoN was manufactured successfully in experiment. Its intrinsic properties remain to be explored theoretically, in depth. The intrinsic properties of a MoN monolayer are investigated by first-principles calculations. The distinct geometric properties of the outermost Mo and N surfaces are discovered. We predict an extremely high work function of 6.3 eV of the N surface, which indicates the great value of the 2D MoN for application in the semiconductor industry. We further explore the potential of 2D MoN as anode material for lithium-ion batteries. It is found that the adsorption energy of a single Li atom on an MoN surface can be as low as -4.04 eV. The small diffusion barriers (0.41 eV) and high theoretical maximum capacity (406 mAh · g-1 with the inclusion of multilayer adsorption) all imply an outstanding lithium-ion battery performance by 2D MoN.

  18. Metallic MoN Layer and its Application as Anode for Lithium-ion Batteries.

    Science.gov (United States)

    Zhang, Qiaoxuan; Ma, Jiachen; Lei, Ming; Quhe, Ruge

    2018-02-06

    Recently, two-dimensional (2D) metallic MoN was manufactured successfully in experiment, while its intrinsic properties remain to be explored theoretically in depth. The intrinsic properties of MoN monolayer are investigated by first-principles calculations. Distinct geometric properties of the outmost Mo and N surfaces are discovered. We predict an extremely high work function of 6.3 eV of the N surface, which indicates great value of the 2D MoN for application in the semiconductor industry. We further explore the potential of 2D MoN as anode material for lithium-ion batteries. It is found that adsorption energy of the single Li atom on MoN surface can be as low as - 4.04 eV. The small diffusion barriers (0.41 eV) and high theoretical maximum capacity (406 mAh∙g-1 with the inclusion of multilayer adsorption) all imply the outstanding lithium-ion batteries performance by 2D MoN. © 2018 IOP Publishing Ltd.

  19. Emission wavelength red-shift by using ;semi-bulk; InGaN buffer layer in InGaN/InGaN multiple-quantum-well

    Science.gov (United States)

    Alam, Saiful; Sundaram, Suresh; Li, Xin; El Gmili, Youssef; Elouneg-Jamroz, Miryam; Robin, Ivan Christophe; Patriarche, Gilles; Salvestrini, Jean-Paul; Voss, Paul L.; Ougazzaden, Abdallah

    2017-12-01

    We report an elongation of emission wavelength by inserting a ∼70 nm thick high quality semi-bulk (SB) InyGa1-yN buffer layer underneath the InxGa1-xN/InyGa1-yN (x > y) multi-quantum-well (MQW).While the MQW structure without the InGaN SB buffer is fully strained on the n-GaN template, the MQW structure with the buffer has ∼15% relaxation. This small relaxation along with slight compositional pulling induced well thickness increase of MQW is believed to be the reason for the red-shift of emission wavelength. In addition, the SB InGaN buffer acts as an electron reservoir and also helps to reduce the Quantum Confined Stark Effect (QCSE) and thus increase the emission intensity. In this way, by avoiding fully relaxed buffer induced material degradation, a longer emission wavelength can be achieved by just using InGaN SB buffer while keeping all other growth conditions the same as the reference structure. Thus, a reasonably thick fully strained or very little relaxed InGaN buffer, which is realized by ;semi-bulk; approach to maintain good InGaN material quality, can be beneficial for realizing LEDs, grown on top of this buffer, emitting in the blue to cyan to green regime without using excess indium (In).

  20. Crystal orientations of InSb films grown on a Si(111) substrate by inserting AlSb buffer layer

    International Nuclear Information System (INIS)

    Murata, K.; Ahmad, N.B.; Mori, M.; Tambo, T.; Maezawa, K.

    2008-01-01

    The heteroepitaxial growth of InSb film via AlSb buffer layer on a Si(111) substrate was performed in an ultra high vacuum. The grown InSb films were characterized by X-ray diffraction and atomic force microscopy. XRD patterns (Φ-scan) of the samples showed different epitaxial relationship between InSb/Si and InSb/AlSb/Si. It is found that surface condition has a significant influence on the growth of InSb films and the surface of InSb films became rough due to the high mixture ratio of domains. The two-step growth procedure was also tried to further improve the crystal quality of the InSb films. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Direct ceramic inkjet printing of yttria-stabilized zirconia electrolyte layers for anode-supported solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Tomov, R.I.; Hopkins, S.C. [Applied Superconductivity and Cryoscience Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB4 3QZ (United Kingdom); Krauz, M.; Kluczowski, J.R. [Institute of Power Engineering, Ceramic Department CEREL, 36-040 Boguchwala (Poland); Jewulski, J. [Institute of Power Engineering, Fuel Cells Department, 02-981 Warsaw (Poland); Glowacka, D.M. [Detector Physics Group, Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Glowacki, B.A. [Applied Superconductivity and Cryoscience Group, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB4 3QZ (United Kingdom); Institute of Power Engineering, Fuel Cells Department, 02-981 Warsaw (Poland)

    2010-11-01

    Electromagnetic drop-on-demand direct ceramic inkjet printing (EM/DCIJP) was employed to fabricate dense yttria-stabilized zirconia (YSZ) electrolyte layers on a porous NiO-YSZ anode support from ceramic suspensions. Printing parameters including pressure, nozzle opening time and droplet overlapping were studied in order to optimize the surface quality of the YSZ coating. It was found that moderate overlapping and multiple coatings produce the desired membrane quality. A single fuel cell with a NiO-YSZ/YSZ ({proportional_to}6 {mu}m)/LSM + YSZ/LSM architecture was successfully prepared. The cell was tested using humidified hydrogen as the fuel and ambient air as the oxidant. The cell provided a power density of 170 mW cm{sup -2} at 800 C. Scanning electron microscopy (SEM) revealed a highly coherent dense YSZ electrolyte layer with no open porosity. These results suggest that the EM/DCIJP inkjet printing technique can be successfully implemented to fabricate electrolyte coatings for SOFC thinner than 10 {mu}m and comparable in quality to those fabricated by more conventional ceramic processing methods. (author)

  2. Effect of dopent on the structural and optical properties of ZnS thin film as a buffer layer in solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Vashistha, Indu B., E-mail: indu-139@yahoo.com; Sharma, S. K. [Department of Physics, Malaviya National Institute of Technology, Jaipur 302017 (India); Sharma, Mahesh C. [National Institute of Solar Energy, Gurgaon (India); Sharma, Ramphal [Thin Film and Nanotechnology Lab, Department of Physics Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 43100 (India)

    2015-08-28

    In order to find the suitable alternative of toxic CdS buffer layer, deposition of pure ZnS and doped with Al by chemical bath deposition method have been reported. Further as grown pure and doped thin films have been annealed at 150°C. The structural and surface morphological properties have been characterized by X-Ray diffraction (XRD) and Atomic Force Microscope (AFM).The XRD analysis shows that annealed thin film has been polycrystalline in nature with sphalerite cubic crystal structure and AFM images indicate increment in grain size as well as growth of crystals after annealing. Optical measurement data give band gap of 3.5 eV which is ideal band gap for buffer layer for solar cell suggesting that the obtained ZnS buffer layer is suitable in a low-cost solar cell.

  3. Effect of a gate buffer layer on the performance of a 4H-SiC Schottky barrier field-effect transistor

    International Nuclear Information System (INIS)

    Zhang Xianjun; Yang Yintang; Chai Changchun; Duan Baoxing; Song Kun; Chen Bin

    2012-01-01

    A lower doped layer is inserted between the gate and channel layer and its effect on the performance of a 4H-SiC Schottky barrier field-effect transistor (MESFET) is investigated. The dependences of the drain current and small signal parameters on this inserted gate-buffer layer are obtained by solving one-dimensional (1-D) and two-dimensional (2-D) Poisson's equations. The drain current and small signal parameters of the 4H-SiC MESFET with a gate-buffer layer thickness of 0.15 μm are calculated and the breakdown characteristics are simulated. The results show that the current is increased by increasing the thickness of the gate-buffer layer; the breakdown voltage is 160 V, compared with 125 V for the conventional 4H-SiC MESFET; the cutoff frequency is 27 GHz, which is higher than 20 GHz of the conventional structure due to the lower doped gate-buffer layer. (semiconductor devices)

  4. Engineering of the energetic structure of the anode of organic photovoltaic devices utilizing hot-wire deposited transition metal oxide layers

    Energy Technology Data Exchange (ETDEWEB)

    Vasilopoulou, M., E-mail: mariva@imel.demokritos.gr [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece); Stathopoulos, N.A.; Savaidis, S.A. [Department of Electronics, Technological and Educational Institute (TEI) of Piraeus, Petrou Ralli & Thivon, 12244 Aegaleo (Greece); Kostis, I. [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece); Department of Electronics, Technological and Educational Institute (TEI) of Piraeus, Petrou Ralli & Thivon, 12244 Aegaleo (Greece); Papadimitropoulos, G. [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece); Davazoglou, D., E-mail: d.davazoglou@imel.demokritos.gr [Institute of Nanoscience and Nanotechnology, Department of Microelectronics, National Center for Scientific Research Demokritos, POB 60228, 15310 Agia Paraskevi, Attiki (Greece)

    2015-09-30

    Graphical abstract: In this work we perform successful engineering of the anode of organic photovoltaics based on poly(3-hexylthiophene):[6,6]-phenyl butyric acid methyl ester blends by using metal oxide transport layers exhibiting shallow gap states which act as a barrier-free path for hole transport toward the anode. - Highlights: • Interface engineering of the anode. • Organic photovoltaics (OPVs). • Shallow gap states. • Barrier-free hole transport. • Design rules for interface engineering in OPVs. - Abstract: In this work we use hydrogen deposited molybdenum and tungsten oxides (chemically described as H:MO{sub x}x ≤ 3 where M = Mo or W) to control the energetics at the anode of bulk heterojunction (BHJ) organic photovoltaics (OPVs) based on poly(3-hexylthiophene):[6,6]-phenyl butyric acid methyl ester (P3HT:PC{sub 71}BM) blends. Significantly improved current densities and open circuit voltages were achieved as a result of improved hole transport from the P3HT highest occupied molecular orbital (HOMO) toward indium tin oxide (ITO) anode. This was attributed to the formation of shallow gap states in these oxides which are located just below the Fermi level and above the polymer HOMO and thus may act as a barrier-free path for the extraction of holes. Consequently, these states can be used for controlling the energetic structure of the anode of OPVs. By using ultraviolet photoelectron spectroscopy it was found that dependent on the deposition conditions these gap states and work function of the metal oxides may be tailored to contribute to the precise alignment of the HOMO of the organic semiconductor (OSC) with the Fermi level of the anode electrode resulting in further enhancement of the device performance.

  5. Effect of thermal annealing treatment with titanium chelate on buffer layer in inverted polymer solar cells

    Science.gov (United States)

    Liu, Zhiyong; Wang, Ning; Fu, Yan

    2016-12-01

    The solution processable electron extraction layer (EEL) is crucial for polymer solar cells (PSCs). Here, we investigated titanium (diisopropoxide) bis(2,4-pentanedionate) (TIPD) as an EEL and fabricated inverted PSCs with a blend of poly(3-hexylthiophene) (P3HT) and indene-C60 bisadduct (ICBA) acting as the photoactive layer, with a structure of ITO/TIPD/P3HT:ICBA/MoO3/Ag. After thermal annealing treatment at 150 °C for 15 min, the PSC performances increased from 3.85% to 6.84% and they achieve stable power conversion efficiency (PCE), with a similar PCE compared with TiO2 as an EEL by the vacuum evaporated method. Fourier transform infrared spectroscopy (FTIR) and ultraviolet photoelectron spectroscopy (UPS) confirmed that the TIPD decomposed and formed the Tidbnd O bond, and the energy level of the lowest unoccupied molecular orbital and the highest occupied molecular orbital increased. The space charge limited current (SCLC) measurements further confirmed the improvement in electron collection and the transport ability using TIPD as the EEL and thermal annealing.

  6. Improved efficiency of organic solar cells using Au NPs incorporated into PEDOT:PSS buffer layer

    Science.gov (United States)

    Otieno, Francis; Shumbula, Ndivhuwo P.; Airo, Mildred; Mbuso, Mlambo; Moloto, Nosipho; Erasmus, Rudolph M.; Quandt, Alexander; Wamwangi, Daniel

    2017-08-01

    Au based plasmonic phenomenon inside the hole transport layer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) of an organic solar cell based on blend of poly(3-hexylthiophene) (P3HT) and [6:6]-phenyl-C61-butyric acid (PCBM) is investigated. The concentration of the Au nanoparticles synthesized by wet chemical reduction is one of the key factors to strong light trapping when the spherical gold nanoparticles are blended into the PEDOT:PSS solution. Studies of the influence of the concentration of nanoparticles distribution in the PEDOT:PSS were carried out using UV-Vis spectroscopy and atomic force microscopy. Electrical characteristics of the pristine device and of device with metallic nanostructures were analyzed from J -V characteristics to observe the plasmonic effects on the performance in the P3HT:PCBM organic solar cells. The origin of the photocurrent enhancements with varying Au nanoparticles concentrations on PEDOT:PSS are discussed.

  7. Vertically Oriented Growth of GaN Nanorods on Si Using Graphene as an Atomically Thin Buffer Layer.

    Science.gov (United States)

    Heilmann, Martin; Munshi, A Mazid; Sarau, George; Göbelt, Manuela; Tessarek, Christian; Fauske, Vidar T; van Helvoort, Antonius T J; Yang, Jianfeng; Latzel, Michael; Hoffmann, Björn; Conibeer, Gavin; Weman, Helge; Christiansen, Silke

    2016-06-08

    The monolithic integration of wurtzite GaN on Si via metal-organic vapor phase epitaxy is strongly hampered by lattice and thermal mismatch as well as meltback etching. This study presents single-layer graphene as an atomically thin buffer layer for c-axis-oriented growth of vertically aligned GaN nanorods mediated by nanometer-sized AlGaN nucleation islands. Nanostructures of similar morphology are demonstrated on graphene-covered Si(111) as well as Si(100). High crystal and optical quality of the nanorods are evidenced through scanning transmission electron microscopy, micro-Raman, and cathodoluminescence measurements supported by finite-difference time-domain simulations. Current-voltage characteristics revealed high vertical conduction of the as-grown GaN nanorods through the Si substrates. These findings are substantial to advance the integration of GaN-based devices on any substrates of choice that sustains the GaN growth temperatures, thereby permitting novel designs of GaN-based heterojunction device concepts.

  8. Ge self-assembled islands grown on SiGe/Si(0 0 1) relaxed buffer layers

    International Nuclear Information System (INIS)

    Shaleev, M.V.; Novikov, A.V.; Kuznetsov, O.A.; Yablonsky, A.N.; Vostokov, N.V.; Drozdov, Yu.N.; Lobanov, D.N.; Krasilnik, Z.F.

    2005-01-01

    In this work, the results obtained in growth of Ge(Si) self-assembled islands on relaxed Si 1-x Ge x /Si(0 0 1) buffer layers (x ∼ 25%) and their photoluminescence study are presented. It is found out that growth of Ge(Si)/Si 1-x Ge x islands proceeds with an abrupt change in the surface morphology that is similar to the earlier observed transition (from dome to hut islands with a decreasing Ge growth temperature) in the case of island growth on Si(0 0 1) substrates. It is revealed that in growth of Ge(Si)/Si 1-x Ge x islands, in contrast to the Ge(Si)/Si(0 0 1) islands case, the interval of growth temperatures, in which there is a change in the islands morphology (dome-hut transition) shifts towards higher temperatures. For the first time a photoluminescence signal from Ge(Si) self-assembled islands embedded in a strained Si layer is observed

  9. High Resolution 3D Experimental Investigation of Flow Structures and Turbulence Statistics in the Viscous and Buffer Layer

    Science.gov (United States)

    Sheng, Jian; Malkiel, Edwin; Katz, Joseph

    2006-11-01

    Digital Holographic Microscopy is implemented to perform 3D velocity measurement in the near-wall region of a turbulent boundary layer in a square channel over a smooth wall at Reτ=1,400. The measurements are performed at a resolution of ˜1μm over a sample volume of 1.5x2x1.5mm (x^+=50, y^+=60, z^+=50), sufficient for resolving buffer layer structures and for measuring the instantaneous wall shear stress distributions from velocity gradients in the sublayer. The data provides detailed statistics on the spatial distribution of both wall shear stress components along with the characteristic flow structures, including streamwise counter-rotating vortex pairs, multiple streamwise vortices, and rare hairpins. Conditional sampling identifies characteristic length scales of 70 wall units in spanwise and 10 wall units in wall-normal direction. In the region of high stress, the conditionally averaged flow consists of a stagnation-like sweeping motion induced by a counter rotating pair of streamwise vortices. Regions with low stress are associated with ejection motion, also generated by pairs of counter-rotating vortices. Statistics on the local strain and geometric alignment between strain and vorticity shows that the high shear generating vortices are inclined at 45 to streamwise direction, indicating that vortices are being stretched. Results of on-going analysis examines statistics of helicity, strain and impacts of near-wall structures.

  10. Efficient inverted bulk-heterojunction solar cells from low-temperature processing of amorphous ZnO buffer layers

    KAUST Repository

    Jagadamma, Lethy Krishnan

    2014-01-01

    In this report, we demonstrate that solution-processed amorphous zinc oxide (a-ZnO) interlayers prepared at low temperatures (∼100 °C) can yield inverted bulk-heterojunction (BHJ) solar cells that are as efficient as nanoparticle-based ZnO requiring comparably more complex synthesis or polycrystalline ZnO films prepared at substantially higher temperatures (150-400 °C). Low-temperature, facile solution-processing approaches are required in the fabrication of BHJ solar cells on flexible plastic substrates, such as PET. Here, we achieve efficient inverted solar cells with a-ZnO buffer layers by carefully examining the correlations between the thin film morphology and the figures of merit of optimized BHJ devices with various polymer donors and PCBM as the fullerene acceptor. We find that the most effective a-ZnO morphology consists of a compact, thin layer with continuous substrate coverage. In parallel, we emphasize the detrimental effect of forming rippled surface morphologies of a-ZnO, an observation which contrasts with results obtained in polycrystalline ZnO thin films, where rippled morphologies have been reported to improve efficiency. After optimizing the a-ZnO morphology at low processing temperature for inverted P3HT:PCBM devices, achieving a power conversion efficiency (PCE) of ca. 4.1%, we demonstrate inverted solar cells with low bandgap polymer donors on glass/flexible PET substrates: PTB7:PC71BM (PCE: 6.5% (glass)/5.6% (PET)) and PBDTTPD:PC71BM (PCE: 6.7% (glass)/5.9% (PET)). Finally, we show that a-ZnO based inverted P3HT:PCBM BHJ solar cells maintain ca. 90-95% of their initial PCE even after a full year without encapsulation in a nitrogen dry box, thus demonstrating excellent shelf stability. The insight we have gained into the importance of surface morphology in amorphous zinc oxide buffer layers should help in the development of other low-temperature solution-processed metal oxide interlayers for efficient flexible solar cells. This journal is

  11. Effect of AlSb buffer layer thickness on heteroepitaxial growth of InSb films on a Si(001) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Mori, M. [Nano and Functional Material Sciences, Graduate School of Science and Engineering, University of TOYAMA, Gofuku 3190, Toyama 930-8555 (Japan)], E-mail: morimasa@eng.u-toyama.ac.jp; Murata, K.; Fujimoto, N.; Tatsuyama, C.; Tambo, T. [Nano and Functional Material Sciences, Graduate School of Science and Engineering, University of TOYAMA, Gofuku 3190, Toyama 930-8555 (Japan)

    2007-07-31

    Aluminum antimonide (AlSb) layers with various thickness ranged from about 8 to 250 nm were grown at 520 deg. C as the buffer layer for the heteroepitaxial growth of InSb films on Si(001) substrates. InSb films were grown at 400 deg. C on the AlSb/Si(001), and were characterized by X-ray diffraction (XRD), atomic force microscope, as a function of the thickness of the AlSb layer. The XRD patterns of the InSb films grown on the AlSb layers show that even if the AlSb buffer layer, whose surface consists of many islands, is as thin as 8 nm, it is effective for the heteroepitaxial growth of InSb film on a Si(001) substrate, and the AlSb layer of about 40 nm is thick enough to grow heteroepitaxial InSb films on the Si(001) substrate. The results of the {phi} scan patterns of the films show that InSb films on a Si(001) substrate with AlSb buffer layer were heteroepitaxially grown without any rotation in the growth plane.

  12. Effect of AlSb buffer layer thickness on heteroepitaxial growth of InSb films on a Si(001) substrate

    International Nuclear Information System (INIS)

    Mori, M.; Murata, K.; Fujimoto, N.; Tatsuyama, C.; Tambo, T.

    2007-01-01

    Aluminum antimonide (AlSb) layers with various thickness ranged from about 8 to 250 nm were grown at 520 deg. C as the buffer layer for the heteroepitaxial growth of InSb films on Si(001) substrates. InSb films were grown at 400 deg. C on the AlSb/Si(001), and were characterized by X-ray diffraction (XRD), atomic force microscope, as a function of the thickness of the AlSb layer. The XRD patterns of the InSb films grown on the AlSb layers show that even if the AlSb buffer layer, whose surface consists of many islands, is as thin as 8 nm, it is effective for the heteroepitaxial growth of InSb film on a Si(001) substrate, and the AlSb layer of about 40 nm is thick enough to grow heteroepitaxial InSb films on the Si(001) substrate. The results of the φ scan patterns of the films show that InSb films on a Si(001) substrate with AlSb buffer layer were heteroepitaxially grown without any rotation in the growth plane

  13. Digital to analog resistive switching transition induced by graphene buffer layer in strontium titanate based devices.

    Science.gov (United States)

    Wan, Tao; Qu, Bo; Du, Haiwei; Lin, Xi; Lin, Qianru; Wang, Da-Wei; Cazorla, Claudio; Li, Sean; Liu, Sidong; Chu, Dewei

    2018-02-15

    Resistive switching behaviour can be classified into digital and analog switching based on its abrupt and gradual resistance change characteristics. Realizing the transition from digital to analog switching in the same device is essential for understanding and controlling the performance of the devices with various switching mechanisms. Here, we investigate the resistive switching in a device made with strontium titanate (SrTiO 3 ) nanoparticles using X-ray diffractometry, scanning electron microscopy, Raman spectroscopy, and direct electrical measurements. It is found that the well-known rupture/formation of Ag filaments is responsible for the digital switching in the device with Ag as the top electrode. To modulate the switching performance, we insert a reduced graphene oxide layer between SrTiO 3 and the bottom FTO electrode owing to its good barrier property for the diffusion of Ag ions and high out-of-plane resistance. In this case, resistive switching is changed from digital to analog as determined by the modulation of interfacial resistance under applied voltage. Based on that controllable resistance, potentiation and depression behaviours are implemented as well. This study opens up new ways for the design of multifunctional devices which are promising for memory and neuromorphic computing applications. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Efficiency Enhancement of Perovskite Solar Cells via Electrospun CuO Nanowires as Buffer Layers.

    Science.gov (United States)

    Sun, Qinjun; Zhou, Shaolong; Shi, Xiaolei; Wang, Xiaochun; Gao, Liyan; Li, Zhanfeng; Hao, Yuying

    2018-04-04

    CuO nanowires (NWs) with the diameters ranging from 130 to 275 nm have been successfully prepared by electrospinning technique, followed by a calcination process. Inverted planar heterojunction perovskite solar cells (PSCs) with the structure of indium tin oxide/CuO NWs/poly(3,4-ethylenedioxythiophene) (PEDOT):poly(styrenesulphonate) (PSS)/CH 3 NH 3 PbI 3 /phenyl C 61 -butyric acid methyl ester/Bphen/Ag were designed, achieving a best power conversion efficiency (PCE) of 16.87%, which is 21% improvement compared to that of the control PSCs without CuO NWs. By the characterizations of an optical microscope, X-ray diffraction, and scanning electron microscopy, it was found that CuO NWs have uniform morphology and orderly arrangement. Electrochemical impedance spectrometry and external quantum efficiency were used to reveal the effect of CuO NWs on the performance of PSCs. Compared to ZnO NWs with the same diameters and quantitative analysis based on a simple model, we conclude that the improvement of PCE by about 13% can be ascribed to the increase of the PEDOT:PSS/CH 3 NH 3 PbI 3 interface area and the remaining increase of 8% can be attributed to the higher hole mobility of the CuO NWs/PEDOT:PSS composite film. The results indicate that the efficiency of PSCs will have a significant enhancement when the optimal CuO NWs are introduced into the charge transport layer.

  15. Effects of a GaSb buffer layer on an InGaAs overlayer grown on Ge(111) substrates: Strain, twin generation, and surface roughness

    Science.gov (United States)

    Kajikawa, Y.; Nishigaichi, M.; Tenma, S.; Kato, K.; Katsube, S.

    2018-04-01

    InGaAs layers were grown by molecular-beam epitaxy on nominal and vicinal Ge(111) substrates with inserting GaSb buffer layers. High-resolution X-ray diffraction using symmetric 333 and asymmetric 224 reflections was employed to analyze the crystallographic properties of the grown layers. By using the two reflections, we determined the lattice constants (the unit cell length a and the angle α between axes) of the grown layers with taking into account the rhombohedral distortion of the lattices of the grown layers. This allowed us the independent determination of the strain components (perpendicular and parallel components to the substrate surface, ε⊥ and ε//) and the composition x of the InxGa1-xAs layers by assuming the distortion coefficient D, which is defined as the ratio of ε⊥ against ε//. Furthermore, the twin ratios were determined for the GaSb and the InGaAs layers by comparing asymmetric 224 reflections from the twin domain with that from the normal domain of the layers. As a result, it has been shown that the twin ratio in the InGaAs layer can be decreased to be less than 0.1% by the use of the vicinal substrate together with annealing the GaSb buffer layer during the growth interruption before the InGaAs overgrowth.

  16. Photoactive layered nanocomposites obtained by direct transferring of anodic TiO{sub 2} nanotubes to commodity thermoplastics

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, Ruy, E-mail: ruy.sanzgonzalez@cnr.it [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy); Buccheri, Maria Antonietta; Zimbone, Massimo; Scuderi, Viviana; Amiard, Guillaume; Impellizzeri, Giuliana [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy); Romano, Lucia [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy); Department of Physics, University of Catania, Via Santa Sofia 64, I-95123 Catania (Italy); Privitera, Vittorio [CNR-IMM, Via Santa Sofia 64, I-95123 Catania (Italy)

    2017-03-31

    Highlights: • Rapid and scalable synthesis of flexible photoactive layered nanocomposites is presented. • The nanocomposites show similar photonic efficiencies to TiO{sub 2} nanotubes and commercial products. • The nanocomposites exhibit antibacterial properties under 1 mW cm{sup −2} UVA. • The synthesis process is solvent-free and reduces the amount of raw materials. - Abstract: TiO{sub 2} nanotubes demonstrated to be a versatile nanostructure for biomaterials, clean energy and water remediation applications. However, the cost of titanium and the poor mechanical properties of the nanotubes hinder their adoption at large scale. This work presents a straightforward and scalable method for transferring photoactive anodic TiO{sub 2} nanotubes from titanium foils to commodity thermoplastic polymers, polypropylene, polyethylene terephthalate, polycarbonate, and polymethylmetacrylate, allowing the reusing of the remaining titanium. The obtained flexible nanocomposites reach a maximum photonic efficiencies of 0.038% (ISO-10678:2010) representing the 93% of photonic efficiency of TiO{sub 2} nanotubes on titanium. In addition, the nanocomposites and TiO{sub 2} nanotubes on titanium present similar antibacterial properties under 1 mW cm{sup −2} UV-A, 60% of Escherichia coli survival after 1 h of exposition. The final objective of this work is to point out main concepts and key parameters for a low-cost fabrication of a photoactive nanocomposite material.

  17. High Cubic-Phase Purity InN on MgO (001) Using Cubic-Phase GaN as a Buffer Layer

    International Nuclear Information System (INIS)

    Sanorpim, S.; Kuntharin, S.; Parinyataramas, J.; Yaguchi, H.; Iwahashi, Y.; Orihara, M.; Hijikata, Y.; Yoshida, S.

    2011-01-01

    High cubic-phase purity InN films were grown on MgO (001) substrates by molecular beam epitaxy with a cubic-phase GaN buffer layer. The cubic phase purity of the InN grown layers has been analyzed by high resolution X-ray diffraction, μ-Raman scattering and transmission electron microscopy. It is evidenced that the hexagonal-phase content in the InN overlayer much depends on hexagonal-phase content in the cubic-phase GaN buffer layer and increases with increasing the hexagonal-phase GaN content. From Raman scattering measurements, in addition, the InN layer with lowest hexagonal component (6%), only Raman characteristics of cubic TO InN and LO InN modes were observed, indicating a formation of a small amount of stacking faults, which does not affect on vibrational property.

  18. In-situ laser processing and microstructural characteristics of YBa2Cu3O7-δ thin films on Si with TiN buffer layer

    International Nuclear Information System (INIS)

    Tiwari, P.; Zheleva, T.; Narayan, J.

    1993-01-01

    The authors have prepared high-quality superconducting YBa 2 Cu 3 O 7 -δ (YBCO) thin films on Si(100) with TiN as a buffer layer using in-situ multitarget deposition system. Both TiN and YBCO thin films were deposited sequentially by KrF excimer laser ( | = 248 nm ) at substrate temperature of 650 C . Thin films were characterized using X-ray diffraction (XRD), four-point-probe ac resistivity, scanning electron microscopy (S E M), transmission electron microscopy (TEM), and Rutherford backscattering (RBS). The TiN buffer layer was epitaxial and the epitaxial relationship was found to be cube on cube with TiN parallel Si. YBCO thin films on Si with TiN buffer layer showed the transition temperature of 90-92K with T co (zero resistance temperature) of 84K. The authors have found that the quality of the buffer layer is very important in determining the superconducting transition temperature of the thin film. The effects of processing parameters and the correlation of microstructural features with superconducting properties are discussed in detail

  19. Cube Texture Formation of Cu-33at.%Ni Alloy Substrates and CeO2 Buffer Layer for YBCO Coated Conductors

    DEFF Research Database (Denmark)

    Tian, Hui; Li, Suo Hong; Ru, Liang Ya

    2014-01-01

    .%Ni alloy substrate with the cube texture fraction of 99.8 % (omega-scan in this substrate were 7.31° and 5.51°, respectively. Furthermore, the cube texture fraction...... of epitaxially grown CeO2 buffer layer was 95 % (omega-scan being 6.98° and 5.92°, respectively....

  20. Hydrothermal Growth and Application of ZnO Nanowire Films with ZnO and TiO2Buffer Layers in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Jiang Chunhua

    2009-01-01

    Full Text Available Abstract This paper reports the effects of the seed layers prepared by spin-coating and dip-coating methods on the morphology and density of ZnO nanowire arrays, thus on the performance of ZnO nanowire-based dye-sensitized solar cells (DSSCs. The nanowire films with the thick ZnO buffer layer (~0.8–1 μm thick can improve the open circuit voltage of the DSSCs through suppressing carrier recombination, however, and cause the decrease of dye loading absorbed on ZnO nanowires. In order to further investigate the effect of TiO2buffer layer on the performance of ZnO nanowire-based DSSCs, compared with the ZnO nanowire-based DSSCs without a compact TiO2buffer layer, the photovoltaic conversion efficiency and open circuit voltage of the ZnO DSSCs with the compact TiO2layer (~50 nm thick were improved by 3.9–12.5 and 2.4–41.7%, respectively. This can be attributed to the introduction of the compact TiO2layer prepared by sputtering method, which effectively suppressed carrier recombination occurring across both the film–electrolyte interface and the substrate–electrolyte interface.

  1. Power Conversion Efficiency and Device Stability Improvement of Inverted Perovskite Solar Cells by Using a ZnO:PFN Composite Cathode Buffer Layer.

    Science.gov (United States)

    Jia, Xiaorui; Zhang, Lianping; Luo, Qun; Lu, Hui; Li, Xueyuan; Xie, Zhongzhi; Yang, Yongzhen; Li, Yan-Qing; Liu, Xuguang; Ma, Chang-Qi

    2016-07-20

    We have demonstrated in this article that both power conversion efficiency (PCE) and performance stability of inverted planar heterojunction perovskite solar cells can be improved by using a ZnO:PFN nanocomposite (PFN: poly[(9,9-bis(3'-(N,N-dimethylamion)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl)-fluorene]) as the cathode buffer layer (CBL). This nanocomposite could form a compact and defect-less CBL film on the perovskite/PC61BM surface (PC61BM: phenyl-C61-butyric acid methyl ester). In addition, the high conductivity of the nanocomposite layer makes it works well at a layer thickness of 150 nm. Both advantages of the composite layer are helpful in reducing interface charge recombination and improving device performance. The power conversion efficiency (PCE) of the best ZnO:PFN CBL based device was measured to be 12.76%, which is higher than that of device without CBL (9.00%), or device with ZnO (7.93%) or PFN (11.30%) as the cathode buffer layer. In addition, the long-term stability is improved by using ZnO:PFN composite cathode buffer layer when compare to that of the reference cells. Almost no degradation of open circuit voltage (VOC) and fill factor (FF) was found for the device having ZnO:PFN, suggesting that ZnO:PFN is able to stabilize the interface property and consequently improve the solar cell performance stability.

  2. Zigzag and Helical AlN Layer Prepared by Glancing Angle Deposition and Its Application as a Buffer Layer in a GaN-Based Light-Emitting Diode

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2012-01-01

    Full Text Available This study investigates an aluminum nitride (AlN nanorod structure sputtered by glancing angle deposition (GLAD and its application as a buffer layer for GaN-based light-emitting diodes (LEDs that are fabricated on sapphire substrates. The ray tracing method is adopted with a three-dimensional model in TracePro software. Simulation results indicate that the zigzag AlN nanorod structure is an optimal buffer layer in a GaN-based LED. Furthermore, the light output power of a GaN-based LED with a zigzag AlN nanorod structure improves to as much as 28.6% at a forward current of 20 mA over that of the GaN-based LED with a normal AlN buffer layer.

  3. Novel 2D Layered Molybdenum Ditelluride Encapsulated in Few-Layer Graphene as High-Performance Anode for Lithium-Ion Batteries.

    Science.gov (United States)

    Ma, Ning; Jiang, Xiao-Yu; Zhang, Lu; Wang, Xiao-Shuang; Cao, Yu-Liang; Zhang, Xian-Zheng

    2018-02-28

    Molybdenum ditelluride nanosheets encapsulated in few-layer graphene (MoTe 2 /FLG) are synthesized by a simple heating method using Te and Mo powder and subsequent ball milling with graphite. The as-prepared MoTe 2 /FLG nanocomposites as anode materials for lithium-ion batteries exhibit excellent electrochemical performance with a highly reversible capacity of 596.5 mAh g -1 at 100 mA g -1 , a high rate capability (334.5 mAh g -1 at 2 A g -1 ), and superior cycling stability (capacity retention of 99.5% over 400 cycles at 0.5 A g -1 ). Ex situ X-ray diffraction and transmission electron microscopy are used to explore the lithium storage mechanism of MoTe 2 . Moreover, the electrochemical performance of a MoTe 2 /FLG//0.35Li 2 MnO 3 ·0.65LiMn 0.5 Ni 0.5 O 2 full cell is investigated, which displays a reversible capacity of 499 mAh g -1 (based on the MoTe 2 /FLG mass) at 100 mA g -1 and a capacity retention of 78% over 50 cycles, suggesting the promising application of MoTe 2 /FLG for lithium-ion storage. First-principles calculations exhibit that the lowest diffusion barrier (0.18 eV) for lithium ions along pathway III in the MoTe 2 layered structure is beneficial for improving the Li intercalation/deintercalation property. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Numerical analysis of the influence of buffer layer thickness on the residual stresses in YBCO/La2Zr2O7/Ni superconducting materials

    International Nuclear Information System (INIS)

    Celik, Erdal; Sayman, Onur; Karakuzu, Ramazan; Ozman, Yilmaz

    2007-01-01

    The present paper addresses a numerical investigation of the influence of buffer layer thickness on the residual stress in YBCO/La 2 Zr 2 O 7 /Ni architectured materials under cryogenic conditions by using classical lamination theory (CLT) and finite element method (FEM) for coated conductor applications. YBCO/La 2 Zr 2 O 7 multilayer films were fabricated on Ni tape substrate using reel-to-reel sol-gel and pulse laser deposition (PLD) systems. The microstructural evolution of high temperature superconducting YBCO film and buffer layers with La 2 Zr 2 O 7 configuration grown on textured Ni tape substrates was investigated by using a scanning electron microscope (SEM). Thermal stress analysis of YBCO/La 2 Zr 2 O 7 /Ni multilayer sample was performed by using CLT in the temperature range of 298-175 K in liquid helium media. The YBCO/La 2 Zr 2 O 7 /Ni sample strip was solved by using FEM for linear or nonlinear cases in the temperature range of 298-3 K in liquid helium media. SEM observations revealed that crack-free, pinhole-free, continuous superconducting film and buffer layer were obtained by sol-gel and PLD systems. In addition to microstructural observations, it was found that the largest compressive stresses and failure occur in La 2 Zr 2 O 7 buffer layer due to its smallest thermal expansion coefficient. The thickness of La 2 Zr 2 O 7 buffer layer affects the failure. The stress component of σ x is the smallest in Ni tape substrate due to its largest thickness

  5. Effect of plasma molybdenized buffer layer on adhesive properties of TiN film coated on Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Lin, E-mail: qinlin@tyut.edu.cn; Yi, Hong; Kong, Fanyou; Ma, Hua; Guo, Lili; Tian, Linhai; Tang, Bin

    2017-05-01

    Highlights: • A molybdenized layer was prepared as a buffer layer under TiN film on Ti6Al4V. • The molybdenized layer can enhance adhesion strength of PVD coatings effectively. • The duplex treated samples increase elastic energy ratio in the impact tests. • The enhancement attributes to the hardness improvement and inverted-S shape elastic modulus profile of the modified layer. - Abstract: Effect of molybdenized buffer layer on adhesion strength of TiN film on Ti6Al4V alloy was investigated. The buffer layer composed of a dense molybdenum deposition layer, a rapid drop zone and a slow fall zone was prepared using double glow plasma surface alloying technique. Scratch tests and low energy repeated impact tests were adopted to comparatively evaluate the duplex treated layers and the single TiN samples. The results show that the critical load was increased from 62 N for the single TiN film to over 100 N for the duplex treated layer. The volume of impact pit, formed in impact tests, of the single TiN samples is 9.15 × 10{sup 6} μm{sup 3}, and about 1.5 times than that of the duplex treated samples. The Leeb hardness values reveal that about 70% impact energy was transferred to the single TiN samples to generate permanent deformation, while that was only about 47% for the duplex treated samples. The mechanism of improving adhesion strength is attributed to synergistic effect due to an inverted-S shape elastic modulus distribution produced by the molybdenized layer.

  6. Reaching state-of-the art requirements for MIM capacitors with a single-layer anodic Al2O3 dielectric and imprinted electrodes

    Science.gov (United States)

    Hourdakis, Emmanouel; Nassiopoulou, Androula G.

    2017-07-01

    Metal-Insulator-Metal (MIM) capacitors with a high capacitance density and low non-linearity coefficient using a single-layer dielectric of barrier-type anodic alumina (Al2O3) and an imprinted bottom Al electrode are presented. Imprinting of the bottom electrode aimed at increasing the capacitor effective surface area by creating a three-dimensional MIM capacitor architecture. The bottom Al electrode was only partly nanopatterned so as to ensure low series resistance of the MIM capacitor. With a 3 nm thick anodic Al2O3 dielectric, the capacitor with the imprinted electrode showed a 280% increase in capacitance density compared to the flat electrode capacitor, reaching a value of 20.5 fF/μm2. On the other hand, with a 30 nm thick anodic Al2O3 layer, the capacitance density was 7.9 fF/μm2 and the non-linearity coefficient was as low as 196 ppm/V2. These values are very close to reaching all requirements of the last International Technology Roadmap for Semiconductors for MIM capacitors [ITRS, http://www.itrs2.net/2013-itrs.html for ITRS Roadmap (2013)], and they are achieved by a single-layer dielectric instead of the complicated dielectric stacks of the literature. The obtained results constitute a real progress compared to previously reported results by our group for MIM capacitors using imprinted electrodes.

  7. Electrical modeling of Cu(In,Ga)Se2 cells with ALD-Zn1-xMgxO buffer layers

    Science.gov (United States)

    Pettersson, J.; Edoff, M.; Platzer-Björkman, C.

    2012-01-01

    Electrical modeling of Cu(In,Ga)Se2 solar cells with Zn1-xMgxO buffer layers is performed. A number of different device models are implemented and tested by comparing simulation results and measurement data. Room temperature light-soaking and dark-light cross-over behavior as well as low-temperature characteristics of these cells are studied. The light-soaking improvements in the solar cell parameters are attributed to an increase in buffer donor density, due to persistent photo conductivity, that counteracts charged acceptors in the absorber-buffer region. Dark-light JV-curve cross-over is explained by deep acceptor defects with small electron capture cross-section, in the buffer. Best correspondence to measurements on ZnO and Zn0.83Mg0.17O cells is obtained with models including absorber-buffer interface acceptor states. No wideband-gap surface defect layer is needed to reproduce measurement data.

  8. Application of biuret, dicyandiamide, or urea as a cathode buffer layer toward the efficiency enhancement of polymer solar cells.

    Science.gov (United States)

    Zhao, Xuemei; Xu, Chenhui; Wang, Haitao; Chen, Fei; Zhang, Wenfeng; Zhao, Zhiqiang; Chen, Liwei; Yang, Shangfeng

    2014-03-26

    Three amino-containing small-molecule organic materials-biuret, dicyandiamide (DCDA), and urea-were successfully applied as novel cathode buffer layers (CBLs) in P3HT:PCBM bulk heterojunction polymer solar cells (BHJ-PSCs) for the first time, resulting in obvious efficiency enhancement. Under the optimized condition, the power conversion efficiencies (PCEs) of the CBL-incorporated BHJ-PSC devices are 3.84%, 4.25%, and 4.39% for biuret, DCDA, and urea, which are enhanced by ∼15%, ∼27%, and ∼31%, respectively, compared to the reference poly(3-hexylthiophene-2,5-diyl) : [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) BHJ-PSC device without any CBL. The efficiency enhancement is primarily attributed to the increases of both short-circuit current density (Jsc) and fill factor (FF), for which the enhancement ratio is found to be sensitively dependent on the molecular structure of small-molecule organic materials. The surface morphologies and surface potential changes of the CBL-incorporated P3HT:PCBM photoactive layers were studied by atomic force microscopy and scanning Kelvin probe microscopy, respectively, suggesting the formation of an interfacial dipole layer between the photoactive layer and Al cathode, which may decrease the energy level offset between the work function of Al and the lowest unoccipoed molecular orbital level (LUMO) of the PCBM acceptor and consequently facilitate electron extraction by the Al cathode. The difference in the enhancement effect of biuret, DCDA, and urea is due to their difference on the work function matching with P3HT:PCBM. Besides, the coordination interaction between the lone-pair electrons on the N atoms of the amino (-NH2) group and the Al atoms may prohibit interaction between Al and the thiophene rings of P3HT, contributing to the efficiency enhancement of the CBL-incorporated devices as well. In this sense, the different CBL performance of biuret, DCDA, and urea is also proposed to partially originate from the

  9. Effects of the Molybdenum Oxide/Metal Anode Interfaces on Inverted Polymer Solar Cells

    International Nuclear Information System (INIS)

    Wu Jiang; Guo Xiao-Yang; Xie Zhi-Yuan

    2012-01-01

    Inverted polymer solar cells with molybdenum oxide (MoO 3 ) as an anode buffer layer and different metals (Al or Ag) as anodes are studied. It is found that the inverted cell with a top Ag anode demonstrates enhanced charge collection and higher power conversion efficiency (PCE) compared to the cell with a top Al anode. An 18% increment of PCE is obtained by replacing Al with Ag as the top anode. Further studies show that an interfacial dipole pointing from MoO 3 to Al is formed at MoO 3 /Al interfaces due to electron transfer from Al to MoO 3 while this phenomenon cannot be observed at MoO 3 /Ag interfaces. It is speculated that the electric field at the MoO 3 /Al interface would hinder hole extraction, and hence reduce the short-circuit current

  10. Hard magnetic properties of rapidly annealed NdFeB thin films on Nb and V buffer layers

    International Nuclear Information System (INIS)

    Jiang, H.; Evans, J.; O'Shea, M.J.; Du Jianhua

    2001-01-01

    NdFeB thin films of the form A (20 nm)/NdFeB(d nm)/A(20 nm), where d ranges from 54 to 540 nm and the buffer layer A is Nb or V were prepared on a Si(1 0 0) substrate by magnetron sputtering. The hard Nd 2 Fe 14 B phase is formed by a 30 s rapid anneal or a 20 min anneal. Average crystallite size ranged from 20 to 35 nm with the rapidly annealed samples having the smaller crystallite size. These samples also exhibited a larger coercivity and energy product than those treated by a 20 min vacuum anneal. A maximum coercivity of 26.3 kOe at room temperature was obtained for a Nb/NdFeB (180 nm)/Nb film after a rapid anneal at 725 deg. C. Initial magnetization curves indicate magnetization rotation rather than nucleation of reverse domains is important in the magnetization process. A Brown's equation analysis of the coercivity as a function of temperature allowed us to compare the rapidly annealed and 20 min annealed samples. This analysis suggests that rapid annealing gives higher quality crystalline grains than the 20 min annealed sample leading to the observed large coercivity in the rapidly annealed samples

  11. Study on CexLa1-xO2 Buffer Layer used in Coated Conductors by Chemical Solution Method

    DEFF Research Database (Denmark)

    Zhao, Yue; Suo, Hongli; Grivel, Jean-Claude

    2009-01-01

    Developing multi-functional single buffer layer is one of the most important challenges for simplification of coated conductors configuration. Ladoped CeO2 films were prepared by chemical solution method. And surface morphology and texture quality of the La-doped CeO2 films were investigated...... in details. The results show that the as-obtained pore-free Ce0.9La0.1O2 film are epitaxially deposited on the textured NiW substrate. The 120nm thickness Ce0.9La0.1O2 film is obtained though multi-coating route. The YBCO film with Tco=90.5K, which is deposited on Ce0.9La0.1O2/NiW metallic template by PLD...... method. It suggects that Ce0.9La0.1O2 film prepared by chemical solution route have a promising prospect for the simplification of coated conductors configuration....

  12. Influences of ultrathin amorphous buffer layers on GaAs/Si grown by metal-organic chemical vapor deposition

    Science.gov (United States)

    Hu, Haiyang; Wang, Jun; Cheng, Zhuo; Yang, Zeyuan; Yin, Haiying; Fan, Yibing; Ma, Xing; Huang, Yongqing; Ren, Xiaomin

    2018-04-01

    In this work, a technique for the growth of GaAs epilayers on Si, combining an ultrathin amorphous Si buffer layer and a three-step growth method, has been developed to achieve high crystalline quality for monolithic integration. The influences of the combined technique for the crystalline quality of GaAs on Si are researched in this article. The crystalline quality of GaAs epilayer on Si with the combined technique is investigated by scanning electron microscopy, double crystal X-ray diffraction (DCXRD), photoluminescence, and transmission electron microscopy measurements. By means of this technique, a 1.8-µm-thick high-quality GaAs/Si epilayer was grown by metal-organic chemical vapor deposition. The full-width at half-maximum of the DCXRD rocking curve in the (400) reflection obtained from the GaAs/Si epilayers is about 163 arcsec. Compared with only using three-step growth method, the current technique reduces etch pit density from 3 × 106 cm-2 to 1.5 × 105 cm-2. The results demonstrate that the combined technique is an effective approach for reducing dislocation density in GaAs epilayers on Si.

  13. Effects of Hole-Collecting Buffer Layers and Electrodes on the Performance of Flexible Plastic Organic Photovoltaics

    Directory of Open Access Journals (Sweden)

    Sungho Woo

    2013-01-01

    Full Text Available Here we report the influences of the sheet resistance (Rsheet of a hole-collecting electrode (indium tin oxide, ITO and the conductivity of a hole-collecting buffer layer (poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate, PEDOT:PSS on the device performance of flexible plastic organic photovoltaic (OPV devices. The series resistance (RS of OPV devices steeply increases with increasing Rsheet of the ITO electrode, which leads to a significant decrease of short-circuit current density (JSC and fill factor (FF and power conversion efficiency, while the open-circuit voltage (VOC was almost constant. By applying high-conductivity PEDOT:PSS, the efficiency of OPV devices with high Rsheet values of 160 Ω/□ and 510 Ω/□ is greatly improved, by a factor of 3.5 and 6.5, respectively. These results indicate that the conductivities of ITO and PEDOT:PSS will become more important to consider for manufacturing large-area flexible plastic OPV modules.

  14. Theoretical and experimental study of highly textured GaAs on silicon using a graphene buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Alaskar, Yazeed; Arafin, Shamsul; Lin, Qiyin; Wickramaratne, Darshana; McKay, Jeff; Norman, Andrew G.; Zhang, Zhi; Yao, Luchi; Ding, Feng; Zou, Jin; Goorsky, Mark S.; Lake, Roger K.; Zurbuchen, Mark A.; Wang, Kang L.

    2015-09-01

    A novel heteroepitaxial growth technique, quasi-van der Waals epitaxy, promises the ability to deposit three-dimensional GaAs materials on silicon using two-dimensional graphene as a buffer layer by overcoming the lattice and thermal expansion mismatch. In this study, density functional theory (DFT) simulations were performed to understand the interactions at the GaAs/graphene hetero-interface as well as the growth orientations of GaAs on graphene. To develop a better understanding of the molecular beam epitaxy-grown GaAs films on graphene, samples were characterized by x-ray diffraction (..theta..-2..theta.. scan, ..omega..-scan, grazing incidence XRD and pole figure measurement) and transmission electron microscopy. The realizations of smooth GaAs films with a strong (111) oriented fiber-texture on graphene/silicon using this deposition technique are a milestone towards an eventual demonstration of the epitaxial growth of GaAs on silicon, which is necessary for integrated photonics application.

  15. Heteroepitaxial growth of InSb films on a Si(0 0 1) substrate via AlSb buffer layer

    International Nuclear Information System (INIS)

    Mori, M.; Akae, N.; Uotani, K.; Fujimoto, N.; Tambo, T.; Tatsuyama, C.

    2003-01-01

    AlSb is a more suitable material as buffer layers for the heteroepitaxial growth of InSb films on a Si(0 0 1) substrate than Ge. It reduces the large lattice mismatch of about 19.3% between Si and InSb to about 5.6%. The resistance of AlSb with stoichiometric composition is large enough for the measurement of electrical properties. InSb films grown on the AlSb/Si(0 0 1) substrates by the co-evaporation of elemental indium (In) and antimony (Sb) sources were characterized by Auger electron spectroscopy (AES), X-ray diffraction (XRD) and atomic force microscopy (AFM), as a function of growth temperature. The thickness of grown InSb films was about 0.8-1.0 μm. The surface morphology and the crystal quality of the grown films strongly depend on growth temperature. It is found that the optimized growth temperature is about 300 deg. C to obtain the InSb films with smooth surface and good crystal quality

  16. Comparison of physical and electrical properties of GZO/ZnO buffer layer and GZO as source and drain electrodes of α-IGZO thin-film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jia-Ling; Lin, Han-Yu; Su, Bo-Yuan; Chen, Yu-Cheng [Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Chu, Sheng-Yuan, E-mail: chusy@mail.ncku.edu.tw [Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Liu, Ssu-Yin [Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Chang, Chia-Chiang; Wu, Chin-Jyi [Industrial Technology Research Institute, Mechanical and Systems Research Laboratories, Hsinchu 310, Taiwan (China)

    2014-04-01

    Highlights: • The electrodes of bi-layer GZO/ ZnO and single-layer GZO in α-IGZO TFT were compared. • The TFT performances of two different structures were systematically investigated. • The bi-layer GZO/100-nm ZnO S/D electrodes showed the better TFT device properties. - Abstract: In this research, top-gate bottom-contact thin-film transistors (TFTs) made with amorphous indium gallium zinc oxide (α-IGZO) active layers were grown using the radio-frequency sputtering technique. Two kinds of source and drain (S/D) electrodes, namely bi-layer GZO/100-nm ZnO buffer layer/Corning 1737 and single-layer GZO/Corning 1737, used in the TFT devices and the electric characteristics of the devices were compared. To explain the differences in the TFT performances with these different S/D electrodes, X-ray reflectivity (XRR) and contact angles were measured. The α-IGZO TFT with the bi-layer GZO/100-nm ZnO buffer layer structure as S/D electrodes exhibited superior device performance compared to that of the TFT with a single-layer GZO structure, with a higher thin film density (5.94 g/cm{sup 3}), lower surface roughness (0.817 nm), and larger surface energy (62.07 mJ/m{sup 2}) and better adhesion properties of neighboring α-IGZO films. In addition, the mechanisms responsible for the GZO/100-nm ZnO buffer layer/Corning 1737 structure S/D electrodes improving the device characteristics were systematically investigated. The α-IGZO TFT saturation mobility, subthreshold voltage, on/off current ratio, and the trap density of the GZO/100-nm ZnO buffer layer/Corning 1737 S/D electrodes were 13.5 cm{sup 2} V{sup −1} S{sup −1}, 0.43 V/decade, 3.56 × 10{sup 7}, and 5.65 × 10{sup 12} eV{sup −1} cm{sup −2}, respectively, indicating the potential of this bi-layer structure to be applied to large-area flat-panel displays.

  17. Simultaneous enhancement of photovoltage and charge transfer in Cu{sub 2}O-based photocathode using buffer and protective layers

    Energy Technology Data Exchange (ETDEWEB)

    Li, Changli; Delaunay, Jean-Jacques, E-mail: jean@mech.t.u-tokyo.ac.jp [School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Hisatomi, Takashi; Watanabe, Osamu; Domen, Kazunari [Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakabayashi, Mamiko; Shibata, Naoya [Institute of Engineering Innovation, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-07-18

    Coating n-type buffer and protective layers on Cu{sub 2}O may be an effective means to improve the photoelectrochemical (PEC) water-splitting performance of Cu{sub 2}O-based photocathodes. In this letter, the functions of the buffer layer and protective layer on Cu{sub 2}O are examined. It is found that a Ga{sub 2}O{sub 3} buffer layer can form a buried junction with Cu{sub 2}O, which inhibits Cu{sub 2}O self-reduction as well as increases the photovoltage through a small conduction band offset between the two semiconductors. The introduction of a TiO{sub 2} thin protective layer not only improves the stability of the photocathode but also enhances the electron transfer from the photocathode surface into the electrolyte, thus resulting in an increase in photocurrent at positive potentials. These results show that the selection of overlayers with appropriate conduction band positions provides an effective strategy for obtaining a high photovoltage and high photocurrent in PEC systems.

  18. Investigation on internal electric field distribution of organic light-emitting diodes (OLEDs) with Eu{sub 2}O{sub 3} buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Shengwei; Ma, Dongge [State Key Laboratory of Polymer Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022 Changchun (China)

    2009-11-15

    We have found that organic light-emitting diode (OLED) performance was highly improved by using europium oxide (Eu{sub 2}O{sub 3}) as a buffer layer on indium tin oxide (ITO) in OLEDs based on tris-(8-hydroxyquinoline) aluminium (Alq{sub 3}), which showed low turn-on voltage, high luminance, and high electroluminescent (EL) efficiency. The thickness of Eu{sub 2}O{sub 3} generally was 0.5-1.5 nm. We investigated the effects of Eu{sub 2}O{sub 3} on internal electric field distributions in the device through the analysis of current-voltage characteristics, and found that the introduction of the buffer layer balanced the internal electric field distributions in hole transport layer (HTL) and electron transport layer (ETL), which should fully explain the role of the buffer layer in improving device performance. Our investigation demonstrates that the hole injection is Fowler-Nordheim (FN) tunnelling and the electron injection is Richardson-Schottky (RS) thermionic emission, which are very significant in understanding the operational mechanism and improving the performance of OLEDs. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. Effect of maleic anhydride-aniline derivative buffer layer on the properties of flexible substrate heterostructures: Indium tin oxide/nucleic acid base/metal

    Energy Technology Data Exchange (ETDEWEB)

    Stanculescu, A., E-mail: sanca@infim.ro [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, M. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Socol, G.; Mihailescu, I.N. [National Institute for Laser, Plasma and Radiation Physics, P.O. Box MG-36, 077125, Bucharest-Magurele (Romania); Girtan, M. [Laboratoire de Photonique d' Angers, Universite d' Angers, 2, Bd. Lavoisier, 49045, Angers (France); Preda, N. [National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125, Bucharest-Magurele (Romania); Albu, A.-M. [Department of Polymer Science, University ' Politehnica' of Bucharest, Bucharest (Romania); Stanculescu, F. [University of Bucharest, Faculty of Physics, Str. Atomistilor nr.405, P.O. Box MG-11, Bucharest-Magurele, 077125 (Romania)

    2011-12-01

    This paper presents some investigations on the properties of guanine (G) and cytosine (C) based heterostructures deposited on flexible substrates. The effects of two types of maleic anhydride-aniline derivatives (maleic anhydride-cyano aniline or maleic anhydride-2,4 dinitroaniline) buffer layer, deposited between indium tin oxide and (G) or (C) layer, on the optical and electrical properties of the heterostructures have been identified. The heterostructures containing a film of maleic anhydride-2,4 dinitroaniline have shown a good transparency and low photoluminescence in visible range. This buffer layer has determined an increase in the conductance only in the heterostructures based on (G) and (C) deposited on biaxially-oriented polyethylene terephthalate substrate.

  20. Effect of a SiO2 buffer layer on the characteristics of In2O3-ZnO-SnO2 films deposited on PET substrates

    International Nuclear Information System (INIS)

    Woo, B.-J.; Hong, J.-S.; Kim, S.-T.; Kim, H.-M.; Park, S.-H.; Kim, J.-J.; Ahn, J.-S.

    2006-01-01

    Transparent and conducting In 2 O 3 -ZnO-SnO 2 (IZTO) thin films were prepared on flexible PET substrates at room temperature by using an ion-gun-assisted sputtering technique. We mainly investigated the effect of a SiO 2 buffer layer, deposited in-between the film and the PET substrate, on the electrical stability of the film under various external stresses caused by moist-heat or violent temperature variations. The insertion of the SiO 2 layer improves structural, optical and electrical properties of the films: The IZTO/SiO 2 /PET film with a buffer shows a change (∼4 %) in the sheet resistance much smaller than that of the IZTO/PET film without a buffer (∼22 %), against a severe thermal stress of the repeated processes between quenching at -25 .deg. C and annealing at 100 .deg. C for 5 min at each process. Under a moist-heat stress at 90 % relative humidity at 80 .deg. C, the IZTO/SiO 2 /PET film responds with only a slight change (∼8.5 %) in the sheet resistance from 30.2 to 33.0 Ω/□ after being exposed for 240 h. The enhanced stability is understood to be the result of the buffer layers acting as a blocking barrier to water vapor or organic solvents diffusing from the PET substrate during deposition or annealing.

  1. Dependence of magnetic anisotropy on MgO thickness and buffer layer in Co20Fe60B20-MgO structure

    Science.gov (United States)

    Yamanouchi, M.; Koizumi, R.; Ikeda, S.; Sato, H.; Mizunuma, K.; Miura, K.; Gan, H. D.; Matsukura, F.; Ohno, H.

    2011-04-01

    We investigated the dependence of perpendicular magnetic anisotropy in CoFeB-MgO on the MgO layer thickness. Magnetization curves show that a clear perpendicular magnetic easy axis is obtainable in a 1.5-nm thick CoFeB layer by depositing MgO of more than three monolayers. We investigated anisotropy in CoFeB-MgO deposited on four different buffer layers. Results show that a counter interface of CoFeB-nonmagnetic metal affects the perpendicular anisotropy of CoFeB/MgO.

  2. Effects of V2O3 buffer layers on sputtered VO2 smart windows: Improved thermochromic properties, tunable width of hysteresis loops and enhanced durability

    Science.gov (United States)

    Long, Shiwei; Cao, Xun; Sun, Guangyao; Li, Ning; Chang, Tianci; Shao, Zewei; Jin, Ping

    2018-05-01

    Vanadium dioxide (VO2) is one of the most well-known thermochromic materials, which exhibits a notable optical change from transparent to reflecting in the infrared region upon a metal-insulator phase transition. For practical applications, VO2 thin films should be in high crystalline quality to obtain a strong solar modulation ability (ΔTsol). Meanwhile, narrow hysteresis loops and robust ambient durability are also indispensable for sensitivity and long-lived utilization, respectively. In this work, a series of high-quality V2O3/VO2 bilayer structures were grown on quartz glass substrates by reactive magnetron sputtering. Basically, the bottom V2O3 acts as the buffer layer to improve the crystallinity of the top VO2, while the VO2 serves as the thermochromic layer to guarantee the solar modulation ability for energy-saving. We observed an obvious increase in ΔTsol of 76% (from 7.5% to 13.2%) for VO2 films after introducing V2O3 buffer layers. Simultaneously, a remarkable reduction by 79% (from 21.9 °C to 4.7 °C) in width of hysteresis loop was obtained when embedding 60 nm V2O3 buffer for 60 nm VO2. In addition, VO2 with non-stoichiometry of V2O3±x buffer demonstrates a broadening hysteresis loops width, which is derived from the lattice distortion caused by lattice imperfection. Finally, durability of VO2 has been significantly improved due to positive effects of V2O3 buffer layer. Our results lead to a comprehensive enhancement in crystallinity of VO2 and shed new light on the promotion of thermochromic property by homologous oxides for VO2.

  3. Electrical double layer modulation of hybrid room temperature ionic liquid/aqueous buffer interface for enhanced sweat based biosensing.

    Science.gov (United States)

    Jagannath, Badrinath; Muthukumar, Sriram; Prasad, Shalini

    2018-08-03

    We have investigated the role of kosmotropic anionic moieties and chaotropic cationic moieties of room temperature hydrophilic ionic liquids in enhancing the biosensing performance of affinity based immunochemical biosensors in human sweat. Two ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM[BF 4 ]) and choline dihydrogen phosphate (Choline[DHP]) were investigated in this study with Choline[DHP] being more kosmotropic in nature having a more protein stabilizing effect based on the hofmeister series. Non-faradaic interfacial charge transfer has been employed as the mechanism for evaluating the formation and the biosensing of capture probe antibodies in room temperature ionic liquids (RTILs)/aqueous human sweat interface. The charge of the ionic moieties were utilized to form compact electrical double layers around the antibodies for enhancing the stability of the antibody capture probes, which was evaluated through zeta potential measurements. The zeta potential measurements indicated stability of antibodies due to electrostatic repulsion of the RTIL charged moieties encompassing the antibodies, thus preventing any aggregation. Here, we report for the first time of non-faradaic electrochemical impedance spectroscopy equivalent circuit model analysis for analyzing and interpreting affinity based biosensing at hybrid electrode/ionic liquid-aqueous sweat buffer interface guided by the choice of the ionic liquid. Interleukin-6 (IL-6) and cortisol two commonly occurring biomarkers in human sweat were evaluated using this method. The limit of detection (LOD) obtained using both ionic liquids for IL-6 was 0.2 pg mL -1 with cross-reactivity studies indicating better performance of IL-6 detection using Choline[DHP] and no response to cross-reactive molecule. The LOD of 0.1 ng/mL was achieved for cortisol and the cross-reactivity studies indicated that cortisol antibody in BMIM[BF 4 ] did not show any signal response to cross-reactive molecules

  4. First-Principles Investigations of the Working Mechanism of 2D h-BN as an Interfacial Layer for the Anode of Lithium Metal Batteries.

    Science.gov (United States)

    Shi, Le; Xu, Ao; Zhao, Tianshou

    2017-01-18

    An issue with the use of metallic lithium as an anode material for lithium-based batteries is dendrite growth, causing a periodic breaking and repair of the solid electrolyte interphase (SEI) layer. Adding 2D atomic crystals, such as h-BN, as an interfacial layer between the lithium metal anode and liquid electrolyte has been demonstrated to be effective to mitigate dendrite growth, thereby enhancing the Columbic efficiency of lithium metal batteries. But the underlying mechanism leading to the reduced dendrite growth remains unknown. In this work, with the aid of first-principle calculations, we find that the interaction between the h-BN and lithium metal layers is a weak van der Waals force, and two atomic layers of h-BN are thick enough to block the electron tunneling from lithium metal to electrolyte, thus prohibiting the decomposition of electrolyte. The interlayer spacing between the h-BN and lithium metal layers can provide larger adsorption energies toward lithium atoms than that provided by bare lithium or h-BN, making lithium atoms prefer to intercalate under the cover of h-BN during the plating process. The combined high stiffness of h-BN and the low diffusion energy barriers of lithium at the Li/h-BN interfaces induce a uniform distribution of lithium under h-BN, therefore effectively suppressing dendrite growth.

  5. Comparison of analytical possibilities of inversion voltammetry of tellurium with cathodic and anodic potential scanning taking layer-by-layer analysis of GaAs-Te films as example

    International Nuclear Information System (INIS)

    Kaplin, A.A.; Portnyagina, Eh.O.; Gridaev, V.F.

    1979-01-01

    Possibility of application in analytical purposes of the process of tellurium precipitation electrosolution from the surfaces of graphite and mercury-graphite electrodes at the cathode scanning of the potential is shown. As a result of comparison of direct and inversion scanning with cathodic and anodic scanning of the potential, variants of voltammetric method of tellurium determination in artificial solutions and, taking the developed method of layer-by-layer analysis of the GaAsTe films as an example, advantage of mercury-graphite electrode with cathodic scanning as compared to graphite electrode with cathode scanning of the potential is shown. Reproducibility of the GaAs film analysis results according to anodic and cathodic tellurium peaks is satisfactory. Maximum deviation from the results of analysis of oxidation peaks and tellurium peduction does not exceed 15 rel. %. Thus, for tellurium concentrations, exceeding 5x10 -6 g-ion/l, both anodic and cathodic scanning of the potential can be used, though error in tellurium determination according to cathodic peaks is 1.5-2.0 times higher. At tellurium amounts lower 5x10 -6 g-ion/l the determination should be carried out according to the peaks of tellurium anodic oxidation from the surface of graphite electrode or according to the peaks of tellurium cathodic reduction from the surface of mercury-graphite electrode

  6. Optimization by simulation of the nature of the buffer, the gap profile of the absorber and the thickness of the various layers in CZTSSe solar cells

    Science.gov (United States)

    Chadel, Meriem; Chadel, Asma; Moustafa Bouzaki, Mohammed; Aillerie, Michel; Benyoucef, Boumediene; Charles, Jean-Pierre

    2017-11-01

    Performances of ZnO/ZnS/CZTSSe polycrystalline thin film solar cells (Copper Zinc Tin Sulphur Selenium-solar cell) were simulated for different thicknesses of the absorber and ZnS buffer layers. Simulations were performed with SCAPS (Solar Cell Capacitance Simulator) software, starting with actual parameters available from industrial data for commercial cells processing. The influences of the thickness of the various layers in the structure of the solar cell and the gap profile of the CZTSSe absorber layer on the performance of the solar cell were studied in detail. Through considerations of recent works, we discuss possible routes to enhance the performance of CZTSSe solar cells towards a higher efficiency level. Thus, we found that for one specific thickness of the absorber layer, the efficiency of the CZTSSe solar cell can be increased when a ZnS layer replaces the usual CdS buffer layer. On the other hand, the efficiency of the solar cell can be also improved when the absorber layer presents a grad-gap. In this case, the maximum efficiency for the CZTSSe cell was found equal to 13.73%.

  7. Effect of oxygen pressure of SiOx buffer layer on the electrical properties of GZO film deposited on PET substrate

    International Nuclear Information System (INIS)

    Ahn, Byung Du; Ko, Young Gun; Oh, Sang Hoon; Song, Jean-Ho; Kim, Hyun Jae

    2009-01-01

    The present work was made to investigate the effect of oxygen pressure of SiO x layer on the electrical properties of Ga-doped ZnO (GZO) films deposited on poly-ethylene telephthalate (PET) substrate by utilizing the pulsed-laser deposition at ambient temperature. For this purpose, the SiO x buffer layers were deposited at various oxygen pressures ranging from 13.3 to 46.7 Pa. With increasing oxygen pressure during the deposition of SiO x layer as a buffer, the electrical resistivity of GZO/SiO x /PET films gradually decreased from 7.6 x 10 -3 to 6.8 x 10 -4 Ω.cm, due to the enhanced mobility of GZO films. It was mainly due to the grain size of GZO films related to the roughened surface of the SiO x buffer layers. In addition, the average optical transmittance of GZO/SiO x /PET films in a visible regime was estimated to be ∼ 90% comparable to that of GZO deposited onto a glass substrate.

  8. Influence of the Ti microstructure on anodic self-organized TiO{sub 2} nanotube layers produced in ethylene glycol electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Macak, J.M., E-mail: jan.macak@upce.cz [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice (Czech Republic); Jarosova, M. [Laboratory of Nanostructures and Nanomaterials, Institute of Physics of the CAS, v.v.i., Na Slovance 2, 18221 Prague 8 (Czech Republic); Jäger, A. [Department of Structure analysis, Institute of Physics of the CAS, v.v.i., Cukrovarnicka 10, 16200 Prague 6 (Czech Republic); Sopha, H. [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 53002 Pardubice (Czech Republic); Klementová, M. [Institute of Inorganic Chemistry of the CAS, v.v.i., Husinec-Rez 1001, Rez 25068 (Czech Republic)

    2016-05-15

    Highlights: • The microstructure of Ti substrates investigated by EBSD. • Comparison of polished vs. unpolished substrates was carried out. • Grain orientation influences the uniformity of self-organized TiO{sub 2} nanotubes. • Tubes with different average diameter grow on grains with different orientation. • Grain size and boundaries influence the number of flaws in the tube layers. - Abstract: The relationship between the microstructure of Ti substrates and the anodic growth of self-organized TiO{sub 2} nanotube layers obtained upon their anodization in the ethylene glycol based electrolytes on these substrates is reported for the first time. Polished Ti sheets with mirror-like surface as well as unpolished Ti foils were considered in this work. Grains with a wide range of crystallographic orientations and sizes were revealed by Electron Backscatter Diffraction (EBSD) and correlated with nanotube growth on both types of substrates. A preferred grain orientation with [0 0 0 1] axis perpendicular to the surface was observed on all substrates. Surfaces of all substrates were anodized for 18 h in ethylene glycol electrolytes containing 88 mM NH{sub 4}F and 1.5% water and thoroughly inspected by SEM. By a precise comparison of Ti substrates before and after anodization, the uniformity of produced self-organized TiO{sub 2} nanotube layers was evaluated in regard to the specific orientation of individual grains. Grains with [0 0 0 1] axis perpendicular to the surface turned out to be the most growth-promoting orientation on polished substrates. No orientation was found to be strictly growth-retarding, but sufficient anodization time (24 h) was needed to obtain uniform nanotube layers on all grains without remnant porous initial oxide. In contrast with polished Ti sheets, no specific orientation was found to significantly promote or retard the nanotube growth in the case of unpolished Ti foils. Finally, the difference between the average nanotube diameters of

  9. Bipolar characteristics of AlGaN/AlN/GaN/AlGaN double heterojunction structure with AlGaN as buffer layer

    International Nuclear Information System (INIS)

    Peng, Enchao; Wang, Xiaoliang; Xiao, Hongling; Wang, Cuimei; Yin, Haibo; Chen, Hong; Feng, Chun; Jiang, Lijuan; Hou, Xun; Wang, Zhanguo

    2013-01-01

    Highlights: •2DEG and 2DHG coexist in the AlGaN/AlN/GaN/AlGaN DH-structure. •The sheet densities of 2DEG and 2DHG vary with buffer Al content and GaN thickness. •The conditions for the disappearance of 2DHG are discussed. •Increasing buffer Al content provides better electron confinement. •Dislocation scattering is reduced in the DH-structure. -- Abstract: This is a theoretical study of AlGaN/AlN/GaN/AlGaN double heterojunction (DH) structure with AlGaN as buffer layer. Our calculation shows that as the buffer Al content increases, though two-dimensional electron gas (2DEG) sheet density decreases, the channel back-barrier caused by polarization-induced electric field in GaN provides better electron confinement. And under certain conditions the DH-structure shows bipolar characteristics, with an additional two-dimensional hole gas (2DHG) formed at GaN/AlGaN interface. The influence of the buffer Al content and GaN channel thickness on the 2DEG and 2DHG sheet densities are investigated, and the conditions for the disappearance of 2DHG are discussed. Also, the mobility inhibited by dislocation scattering is enhanced in DH-structure due to the enhancement of screening effect of the 2DEG

  10. Effects of AlN buffer layers on the structural and the optical properties of GaN epilayers grown on Al2O3 substrates by using plasma-assisted molecular beam epitaxy

    International Nuclear Information System (INIS)

    Jeon, Heechang; Lee, Seungjoo; Kumar, Sunil; Kang, Taewon; Lee, Namhyun; Kim, Taewhan

    2014-01-01

    GaN epilayers on AlN buffer layers with various thicknesses were grown on sapphire substrates by using plasma-assisted molecular-beam epitaxy. The GaN epilayer with an AlN buffer layer was much smaller than the GaN epilayer without an AlN buffer layer. The crystal quality of the GaN active layer was improved by utilizing an AlN layer, which acted as a nucleation layer. The reduced defect density promoted GaN coalition. The double-crystal rocking curves and the photoluminescence spectra showed that the GaN epilayer grown on a 4-nm AlN buffer layer had the best quality among the several kinds of samples. The photoluminescence intensity of the GaN epilayer which is related to the density of the crystal defects was lower when an AlN buffer layer was used the thin AlN nucleation layer protected against stain propagation. These results indicate that GaN epilayers grown on AIN buffer layers hold promise for applications in short-wavelength optoelectronic devices.

  11. Fabrication of a strain-induced high performance NbN ultrathin film by a Nb5N6 buffer layer on Si substrate

    Science.gov (United States)

    Jia, X. Q.; Kang, L.; Gu, M.; Yang, X. Z.; Chen, C.; Tu, X. C.; Jin, B. B.; Xu, W. W.; Chen, J.; Wu, P. H.

    2014-03-01

    Lattice mismatch between NbN and silicon (Si) reduces the superconducting properties of NbN film on Si substrate, and this in turn affects the performance of devices such as the hot electron bolometer (HEB) and superconducting nanowire single photon detector (SNSPD). We have found that the superconducting properties of NbN film on Si will be significantly improved by a Nb5N6 buffer layer. The strain of the NbN film was optimized by varying the thickness of the buffer layer. With 30 nm thick Nb5N6, the zero resistance superconducting transition temperature (TC0) of a 6 nm thick NbN film on Si is up to 13.5 K and the critical current density (JC) of the film is more than 107 A cm-2. All the details of preparation, improvement and characteristics of this film are also presented.

  12. Fabrication of Ni-5 at. %W Long Tapes with CeO2 Buffer Layer by Reel-to-Reel Method

    DEFF Research Database (Denmark)

    Ma, Lin; Tian, Hui; Yue, Zhao

    2015-01-01

    A 10-m-long homemade textured Ni-5at.%W (Ni5W) long tape with a CeO2 buffer layer has been prepared successfully by means of rolling-assisted biaxially textured substrate (RABiTS) route followed by a chemical solution deposition method in a reel-to-reel manner. Globally, the Ni5W substrate and CeO2...... film exhibit high homogeneity in terms of biaxial texture over the tape. The average values of full width at half maximum of in-plane and out-of-plane texture are 7.2° and 6.1° in Ni5W substrate, 7.6° and 6.1° in CeO2 buffer layer, respectively, all of those with a small standard deviation...

  13. Photovoltaic Properties in Interpenetrating Heterojunction Organic Solar Cells Utilizing MoO3 and ZnO Charge Transport Buffer Layers

    Directory of Open Access Journals (Sweden)

    Tetsuro Hori

    2010-11-01

    Full Text Available Organic thin-film solar cells with a conducting polymer (CP/fullerene (C60 interpenetrating heterojunction structure, fabricated by spin-coating a CP onto a C60 deposit thin film, have been investigated and demonstrated to have high efficiency. The photovoltaic properties of solar cells with a structure of indium-tin-oxide/C60/ poly(3-hexylthiophene (PAT6/Au have been improved by the insertion of molybdenum trioxide (VI (MoO3 and zinc oxide charge transport buffer layers. The enhanced photovoltaic properties have been discussed, taking into consideration the ground-state charge transfer between PAT6 and MoO3 by measurement of the differential absorption spectra and the suppressed contact resistance at the interface between the organic and buffer layers.

  14. LaNiO3 buffer layers for high critical current density YBa2Cu3O7-δ and Tl2Ba2CaCu2O8-δ films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5 K, H=0) than films grown directly on a bare LaAlO 3 substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. copyright 1999 American Institute of Physics

  15. LaNiO3 Buffer Layers for High Critical Current Density YBa2Cu3O7δ and Tl2Ba2CaCu2O8δ Films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5K, H=0) than films grown directly on a bare LaAlO 3 substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications

  16. In situ analysis of the Zn(S,O) buffer layer preparation for chalcopyrite solar cells by Zn L-edge X-ray absorption spectroscopy.

    Science.gov (United States)

    Lauermann, Iver; Kropp, Timo; Vottier, Damien; Ennaoui, Ahmed; Eberhardt, Wolfgang; Aziz, Emad F

    2009-02-23

    Bridging the gap between high-vacuum soft X-ray absorption spectroscopy and real systems under ambient conditions probes chemical reactions in situ during deposition and annealing processes. The origin of highly efficient buffer layers in Zn(S,O) is the complex formation between Zn(2+) and the S=C group of thiourea (see schematic), which allows ligand-to-metal and metal-to-ligand charge transfer (LMCT and MLCT).

  17. Growth of thick La{sub 2}Zr{sub 2}O{sub 7} buffer layers for coated conductors by polymer-assisted chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin, E-mail: xzhang@my.swjtu.edu.cn [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity and New Energy Center (SNEC), Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Electrical Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Yong, E-mail: yzhao@swjtu.edu.cn [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity and New Energy Center (SNEC), Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Xia, Yudong [State Key Lab of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Guo, Chunsheng [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity and New Energy Center (SNEC), Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Zhang, Yong [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains, Ministry of Education of China, Superconductivity and New Energy Center (SNEC), Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhang, Han [Department of Physics, Peking University, Beijing 100871 (China)

    2015-06-15

    Highlights: • We develops a low-cost and high-efficient technology of fabricating LZO buffer layers. • Sufficient thickness LZO buffer layers have been obtained on NiW (2 0 0) alloy substrate. • Highly biaxially textured YBCO thin film has been deposited on LZO/NiW. - Abstract: La{sub 2}Zr{sub 2}O{sub 7} (LZO) epitaxial films have been deposited on LaAlO{sub 3} (LAO) (1 0 0) single-crystal surface and bi-axially textured NiW (2 0 0) alloy substrate by polymer-assisted chemical solution deposition, and afterwards studied with XRD, SEM and AFM approaches. Highly in-plane and out-of-plane oriented, dense, smooth, crack free and with a sufficient thickness (>240 nm) LZO buffer layers have been obtained on LAO (1 0 0) single-crystal surface; The films deposited on NiW (2 0 0) alloy substrate are also found with high degree in-plane and out-of-plane texturing, good density with pin-hole-free, micro-crack-free nature and a thickness of 300 nm. Highly epitaxial 500 nm thick YBa{sub 2}Cu{sub 3}O{sub 7−x} (YBCO) thin film exhibits the self-field critical current density (Jc) reached 1.3 MA/cm{sup 2} at 77 K .These results demonstrate the LZO epi-films obtained with current techniques have potential to be a buffer layer for REBCO coated conductors.

  18. Structural and chemical investigations of CBD- and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se2-based thin film solar cells

    International Nuclear Information System (INIS)

    Abou-Ras, D.; Kostorz, G.; Romeo, A.; Rudmann, D.; Tiwari, A.N.

    2005-01-01

    It is known that high-efficiency thin film solar cells based on Cu(In,Ga)Se 2 (CIGS) can be obtained using CdS buffer layers grown by chemical bath deposition (CBD). The highest efficiencies achieved with CdS buffer layers produced by physical vapor deposition (PVD) are significantly lower. To find reasons for this difference, structural and chemical properties of CBD- and PVD-CdS buffer layers and their interfaces with CIGS were investigated by means of bright-field (BF-TEM), high-resolution (HR-TEM) and energy-filtered transmission electron microscopy (EF-TEM), and also by energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). PVD-CdS grains were shown to be clearly larger than the CBD-CdS grains. Also, a large defect density was detected at the PVD-CdS/CIGS interface, which is attributed to the larger lattice mismatch than at the CBD-CdS/CIGS interface. Cu diffusion from CIGS into CdS was found for the CBD- and the PVD-CdS sample. The PVD-CdS/CIGS interface turned out to be quite abrupt, whereas the CBD-CdS/CIGS interface is rather diffuse. The differences in efficiencies of solar cells with CBD- and PVD-CdS buffer layers can partly be explained by referring to the higher defect density and the probable absence of an inversion of the near-interface region from p- to n-type at the PVD-CdS/CIGS interface

  19. Anatase TiO2as a Cheap and Sustainable Buffering Filler for Silicon Nanoparticles in Lithium-Ion Battery Anodes.

    Science.gov (United States)

    Maroni, Fabio; Carbonari, Gilberto; Croce, Fausto; Tossici, Roberto; Nobili, Francesco

    2017-12-08

    The design of effective supporting matrices to efficiently cycle Si nanoparticles is often difficult to achieve and requires complex preparation strategies. In this work, we present a simple synthesis of low-cost and environmentally benign aAnatase TiO 2 nanoparticles as buffering filler for Si nanoparticles (Si@TiO 2 ). The average anatase TiO 2 crystallite size was approximately 5 nm. A complete structural, morphological, and electrochemical characterization was performed. Electrochemical test results show very good specific capacity values of up to 1000 mAh g -1 and cycling at several specific currents, ranging from 500 to 2000 mA g -1 , demonstrating a very good tolerance to high cycling rates. Postmortem morphological analysis shows very good electrode integrity after 100 cycles at 500 mA g -1 specific current. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Sm-doped CeO{sub 2} single buffer layer for YBCO coated conductors by polymer assisted chemical solution deposition (PACSD) method

    Energy Technology Data Exchange (ETDEWEB)

    Li, G.; Pu, M.H.; Sun, R.P.; Wang, W.T.; Wu, W.; Zhang, X.; Yang, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)], E-mail: yzhao@home.swjtu.edu.cn

    2008-10-20

    An over 150 nm thick Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9-x} (SCO) single buffer layer has been deposited on bi-axially textured NiW (2 0 0) alloy substrate. Highly in-plane and out-of-plane oriented, dense, smooth and crack free SCO single layer has been obtained via a polymer-assisted chemical solution deposition (PACSD) approach. YBCO thin film has been deposited equally via a PACSD route on the SCO-buffered NiW, the as grown YBCO yielding a sharp transition at T{sub c0} = 87 K as well as J{sub c}(0 T, 77 K) {approx} 1 MA/cm{sup 2}. These results indicates that RE (lanthanides other than Ce) doping may be an effective approach to improve the critical thickness of solution derived CeO{sub 2} film, which renders it a promising candidate as single buffer layer for YBCO coated conductors.

  1. Non-Stoichiometric Amorphous Indium Selenide Thin Films as a Buffer Layer for CIGS Solar Cells with Various Temperatures in Rapid Thermal Annealing.

    Science.gov (United States)

    Yoo, Myoung Han; Kim, Nam-Hoon

    2016-05-01

    The conventional structure of most of copper indium gallium diselenide (Culn(1-x)Ga(x)Se2, CIGS) solar cells includes a CdS thin film as a buffer layer. Cd-free buffer layers have attracted great interest for use in photovoltaic applications to avoid the use of hazardous and toxic materials. The RF magnetron sputtering method was used with an InSe2 compound target to prepare the indium selenide precursor. Rapid thermal annealing (RTA) was conducted in ambient N2 gas to control the concentration of volatile Se from the precursor with a change in temperature. The nature of the RTA-treated indium selenide thin films remained amorphous under annealing temperatures of ≤ 700 degrees C. The Se concentration of the RTA-treated specimens demonstrated an opposite trend to the annealing temperature. The optical transmittance and band gap energies were 75.33% and 2.451-3.085 eV, respectively, and thus were suitable for the buffer layer. As the annealing temperature increased, the resistivity decreased by an order-of-magnitude from 10(4) to 10(1) Ω-cm. At lower Se concentrations, the conductivity abruptly changed from p-type to n-type without crystallite formation in the amorphous phase, with the carrier concentration in the order of 10(17) cm(-3).

  2. A novel 4H-SiC MESFET with multi-recessed p-buffer layer for high energy-efficiency applications

    Science.gov (United States)

    Jia, Hujun; Wu, Qiuyuan; Hu, Mei; Yang, Zhihui; Ma, Peimiao; Luo, Yehui; Yang, Yintang

    2017-12-01

    In this paper, a novel structure named 4H-SiC metal semiconductor field effect transistor with multi-recessed p-buffer layer named MRB MESFET is proposed and simulated. The design of the new structure takes the power added efficiency into account to reduce energy consumption. The channel is assisted to deplete further and the electric field in the drift region for the new structure is modulated by utilizing a multi-recessed p-buffer layer. Thus, the superior gate-source capacitance is obtained and the larger saturation drain current and breakdown voltage are achieved compared with the double-recessed p-buffer layer structure named DRB MESFET. The simulated results demonstrate that the breakdown voltage and the saturation drain current of the MRB MESFET are about 57.89% and 5.63% greater than that of the DRB MESFET. There is an improvement of 86.5% in the maximum output power density for the proposed structure compared with that of the DRB MESFET when the both RF characteristics are similar to. The related structure parameters m = 0.10 μm, n = 0.20 μm are optimized at the beneficial maximum output power density (Pmax), cut-off frequency (fT) and power added efficiency (PAE). All the results show that the advantages and the potential capacities of the MRB MESFET are greater than the DRB MESFET.

  3. Physical properties and interface studies of YBa sub 2 Cu sub 3 O sub 7 thin films deposited by laser ablation on Si (111) with buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Blank, D.H.A.; Aarnink, W.A.M.; Flokstra, J.; Rogalla, H.; Silfhout, A. van (Univ. of Twente, Dept. of Applied Physics, Enschede (Netherlands))

    1990-10-15

    The physical properties of laser-deposited YBaCuO on Si using a single buffer layer of ZrO{sub 2} and a double layer of NiSi{sub 2} and ZrO{sub 2} have been studied. The influence of the deposition temperature has been investigated. Interface studies were performed by RBS and SAM. SEM pictures, resistivity and critical current measurements complete this study. The granularity of the films is very important for the diffusion of the Si. (orig.).

  4. In As{sub 1–x}Sb{sub x} heteroepitaxial structures on compositionally graded GaInSb and AlGaInSb buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Guseynov, R. R.; Tanriverdiyev, V. A. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan); Kipshidze, G., E-mail: gela.kishidze@stonybrook.ede [Stony Brook, Stony Brook University (United States); Aliyeva, Ye. N.; Aliguliyeva, Kh. V.; Abdullayev, N. A., E-mail: abnadir@mail.ru; Mamedov, N. T. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

    2017-04-15

    Unrelaxed InAs{sub 1–x}Sb{sub x} (x = 0.43 and 0.38) alloy layers are produced by molecular-beam epitaxy on compositionally graded GaInSb and AlGaInSb buffer layers. The high quality of the thin films produced is confirmed by the results of high-resolution X-ray diffraction analysis and micro-Raman studies. The twomode type of transformation of the phonon spectra of InAs{sub 1–x}Sb{sub x} alloys is established.

  5. GaN full-vertical p-i-n rectifiers employing AlGaN:Si conducting buffer layers on n-SiC substrates

    International Nuclear Information System (INIS)

    Yoo, D.; Limb, J.; Ryou, J.-H.; Lee, W.; Dupuis, R.D.

    2006-01-01

    The development of a full-vertical GaN p-i-n rectifier on a 6H n-type SiC substrate by employing a conducting Al x Ga 1-x N:Si (x=∼0.1) buffer layer scheme is reported. In this vertical configuration, the n contact is made on the backside of the SiC substrate using a Ni/Au metallization scheme. Epitaxial layers are grown by low-pressure metal organic chemical vapor deposition. The Al x Ga 1-x N:Si nucleation layer is proven to provide excellent electrical properties while also acting as a good buffer layer for subsequent GaN growth. The reverse breakdown voltage for a relatively thin 2.5 μm thick i region was found to be over -330 V. The devices also show a low on resistance of R on of 7.5x10 -3 Ω cm 2 . This full-vertical configuration provides the advantage of the reduction of sidewall damage from plasma etching and lower forward resistance due to the reduction of current crowding in the bottom n-type layer

  6. Effect of a thermally evaporated bis (2-methyl-8-quninolinato)-4-phenylphenolate cathode buffer layer on the performance of polymer photovoltaic cells

    International Nuclear Information System (INIS)

    Kim, Dal-Ho; Park, Jea-Gun

    2012-01-01

    We investigated the device characteristics of polymer photovoltaic (PV) cells based on a poly(3 hexylthiophene) (P3HT) and [6,6]-phenylC61 butyric acid methyl ester (PCBM) bulk heterojunction with a cathode buffer layer of thermally evaporated bis (2-methyl-8-quninolinato)-4-phenylphenolate (BAlq). A power conversion efficiency (PCE) of 2.46% was obtained with the insertion of a 4-nm-thick BAlq, which was ∼118% increase over that for the cell without a BAlq layer, under Air Mass 1.5 Global (AM 1.5 G) illumination, 100 mW/cm 2 . Moreover, we examined the charge carrier transport property, and found that the hole mobility of the cell was enhancement due to the insertion of a BAlq layer with a thickness of less than 4 nm, which accounted for the improved in the photocurrent and fill factor (FF) due to the better balance of charge carriers. Finally, the BAlq buffer layer was also demonstrated as an optical spacer that improved the optical absorption of the P3HT:PCBM layer, which accounted for the J sc enhancement of the device.

  7. 2D MoS2 as an efficient protective layer for lithium metal anodes in high-performance Li-S batteries

    Science.gov (United States)

    Cha, Eunho; Patel, Mumukshu D.; Park, Juhong; Hwang, Jeongwoon; Prasad, Vish; Cho, Kyeongjae; Choi, Wonbong

    2018-04-01

    Among the candidates to replace Li-ion batteries, Li-S cells are an attractive option as their energy density is about five times higher ( 2,600 Wh kg-1). The success of Li-S cells depends in large part on the utilization of metallic Li as anode material. Metallic lithium, however, is prone to grow parasitic dendrites and is highly reactive to several electrolytes; moreover, Li-S cells with metallic Li are also susceptible to polysulfides dissolution. Here, we show that 10-nm-thick two-dimensional (2D) MoS2 can act as a protective layer for Li-metal anodes, greatly improving the performances of Li-S batteries. In particular, we observe stable Li electrodeposition and the suppression of dendrite nucleation sites. The deposition and dissolution process of a symmetric MoS2-coated Li-metal cell operates at a current density of 10 mA cm-2 with low voltage hysteresis and a threefold improvement in cycle life compared with using bare Li-metal. In a Li-S full-cell configuration, using the MoS2-coated Li as anode and a 3D carbon nanotube-sulfur cathode, we obtain a specific energy density of 589 Wh kg-1 and a Coulombic efficiency of 98% for over 1,200 cycles at 0.5 C. Our approach could lead to the realization of high energy density and safe Li-metal-based batteries.

  8. Ambipolar organic heterojunction transistors based on F16CuPc/CuPc with a MoO3 buffer layer

    Science.gov (United States)

    Mingdong, Yi; Ning, Zhang; Linghai, Xie; Wei, Huang

    2015-10-01

    We fabricated heterojunction organic field-effect transistors (OFETs) using copper phthalocyanine (CuPc) and hexadecafluorophtholocyaninatocopper (F16CuPc) as hole transport layer and electron transport layer, respectively. Compared with F16CuPc based OFETs, the electron field-effect mobility in the heterojunction OFETs increased from 3.1 × 10-3 to 8.7 × 10-3 cm2/(V·s), but the p-type behavior was not observed. To enhanced the hole injection, we modified the source-drain electrodes using the MoO3 buffer layer, and the hole injection can be effectively improved. Eventually, the ambipolar transport characteristics of the CuPc/F16CuPc based OFETs with a MoO3 buffer layer were achieved, and the field-effect mobilities of electron and hole were 2.5 × 10-3 and 3.1 × 10-3 cm2/(V·s), respectively. Project supported by the National Natural Science Foundation of China (Nos. 61475074, 61204095).

  9. Development of buffer layer structure for epitaxial growth of (100)/(001)Pb(Zr,Ti)O3-based thin film on (111)Si wafer

    Science.gov (United States)

    Hayasaka, Takeshi; Yoshida, Shinya; Tanaka, Shuji

    2017-07-01

    This paper reports on the development of a novel buffer layer structure, (100)SrRuO3/(100)LaNiO3/(111)Pt/(111)CeO2, for the epitaxial growth of a (100)/(001)-oriented Pb(Zr,Ti)O3 (PZT)-based thin film on a (111)Si wafer. (111)Pt and (111)CeO2 were epitaxially grown on (111)Si straightforwardly. Then, the crystal orientation was forcibly changed from (111) to (100) at the LaNiO3 layer owing to its strong (100)-self-orientation property, which enabled the cube-on-cube epitaxial growth of the subsequent (100)SrRuO3 layer and preferentially (100)/(001)-oriented PZT-based thin film. The PZT-based epitaxial thin films were comprehensively characterized in terms of the crystallinity, in-plane epitaxial relationships, piezoelectricity, and so forth. This buffer layer structure for the epitaxial growth of PZT can be applied to piezoelectric micro-electro-mechanical systems (MEMS) vibrating ring gyroscopes.

  10. Study of High Quality Indium Nitride Films Grown on Si(100 Substrate by RF-MOMBE with GZO and AlN Buffer Layers

    Directory of Open Access Journals (Sweden)

    Wei-Chun Chen

    2012-01-01

    Full Text Available Wurtzite structure InN films were prepared on Si(100 substrates using radio-frequency metal-organic molecular beam epitaxy (RF-MOMBE system. Ga-doped ZnO (GZO and Amorphous AlN (a-AlN film were used as buffer layers for InN films growth. Structural, surface morphology and optical properties of InN films were investigated by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, and photoluminescence (PL. XRD results indicated that all InN films exhibited preferred growth orientation along the c-axis with different intermediate buffers. TEM images exhibit the InN/GZO growth by two-dimensional mode and thickness about 900 nm. Also, the InN films can be obtained by growth rate about ~1.8 μm/h. Optical properties indicated that the band gap of InN/GZO is about 0.79 eV. These results indicate that the control of buffer layer is essential for engineering the growth of InN on silicon wafer.

  11. Layered double hydroxides for preparing CoMn{sub 2}O{sub 4} nanoparticles as anodes of lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Xu; Ma, Jingjing; Yuan, Ruo, E-mail: yuanruo@swu.edu.cn; Yang, Xia, E-mail: xiayang2@swu.edu.cn

    2017-06-15

    In the field of lithium-ion batteries, CoMn{sub 2}O{sub 4} as an anode material has attracted a wide attention because it inherited the splendid electrochemical performances of Mn and Co-based metal oxides. Compared to graphite, Co-based oxides have a higher capacity which is about twice of the graphite. Moreover, Mn-based oxides have lower operating voltages and manganese exists abundantly in nature. Layered double hydroxides (LDHs), similar with brucite structure, were used as precursor for CoMn{sub 2}O{sub 4} nanoparticles in this work. Under high temperature process, the LDHs decomposed to CoMn{sub 2}O{sub 4} nanoparticles. When evaluated as anode materials for lithium ion batteries, the CoMn{sub 2}O{sub 4} nanoparticles behaved good electrochemical performance with the discharge and charge capacity of 733 mAh g{sup -1} and 721 mAh g{sup -1} at current density of 200 mA g{sup -1} after 100 cycles. This method for preparing CoMn{sub 2}O{sub 4} nanoparticles is easy, which may provide a way for synthesis of other bimetallic oxides and anodes of lithium ion batteries. - Highlights: • Layered double hydroxides were employed as precursors to synthesize CoMn{sub 2}O{sub 4}. • The CoMn{sub 2}O{sub 4} nanoparticles behaved good electrochemical performance. • This study provides a guideline for preparing bimetallic oxides.

  12. Low temperature pulsed direct current magnetron sputtering technique for single phase β-In2S3 buffer layers for solar cell applications

    Science.gov (United States)

    Karthikeyan, Sreejith; Hill, Arthur E.; Pilkington, Richard D.

    2017-10-01

    This work explores the possibilities of using the pulsed direct current (dc) magnetron sputtering (PDCMS) process to deposit an alternative to the cadmium sulphide buffer layer in copper indium gallium diselenide - based solar cells. The main problems with the CdS layer are its toxic nature and its deposition using a chemical bath technique. These factors make it difficult to incorporate into in-line production and significant effort has been expended to find a suitable alternative buffer layer with in-line manufacturing capability. Towards this aim, the material properties of an In2S3 film, sputtered from a powder target, have been investigated. Films were deposited at different substrate temperatures ranging from ;no additional substrate heating; to 250 °C. The deposition of a single phase β-In2S3 without substrate heating/annealing has not previously been reported. The films deposited by the ion-enhanced PdcMS technique without any additional heating were found to be single phase. The grain size increased with increase in substrate temperature. However, this led to a decrease in the sulphur content; as a result the band gap decreased. For solar cell applications, the CdS buffer layer (optical band gap ∼2.4 eV) needs to be replaced with a material which has a band gap wider than 2.4 eV for improved performance and reduction of absorption loss in the blue wavelength region. Ideally the band gap should be between 2.6 and 3.0 eV. Our PdcMS room temperature deposited In2S3 had a measured band gap of 2.77 eV.

  13. Buffer layers for growth of the YBa sub 2 Cu sub 3 O sub 7 sub - sub x films on silicon

    CERN Document Server

    Razumov, S V

    2001-01-01

    The results of the studies on the structural characteristics of the SrTiO sub 3 , NdGaO sub 3 and CeO sub 2 buffer layers, obtained through the ion-plasma spraying on the silicon substrates, are presented. It is shown that the phase composition and internal stresses in the films are strongly dependent on the deposition temperature. The technological conditions of growth of primarily oriented SrTiO sub 3 , NdGaO sub 3 and CeO sub 2 films are dortmund. The structural quality of the obtained buffer films is sufficient for further growth of the YBa sub 2 Cu sub 3 O sub 7 sub - sub x high-quality films on the silicon substrates

  14. Preparation of a Novel Ce0.9La0.1O2/Gd2Zr2O7 Buffer Layer Stack on NiW Alloy Substrates by the MOD Route

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude; Abrahamsen, Asger Bech

    2011-01-01

    An optimized buffer layer architecture prepared by a metal organic deposition method on biaxially textured metallic substrate is proposed and developed successfully. The major achievement of this work is to choose a ${\\rm Ce}_{0.9}{\\rm La}_{0.1}{\\rm O}_{2}$ layer as cap layer that possesses an ex...

  15. Buffered Electrochemical Polishing of Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tian, Hui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States); Corcoran, Sean [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2011-03-01

    The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.

  16. High-Performance Integrated Self-Package Flexible Li-O2Battery Based on Stable Composite Anode and Flexible Gas Diffusion Layer.

    Science.gov (United States)

    Yang, Xiao-Yang; Xu, Ji-Jing; Bao, Di; Chang, Zhi-Wen; Liu, Da-Peng; Zhang, Yu; Zhang, Xin-Bo

    2017-07-01

    With the rising development of flexible and wearable electronics, corresponding flexible energy storage devices with high energy density are required to provide a sustainable energy supply. Theoretically, rechargeable flexible Li-O 2 batteries can provide high specific energy density; however, there are only a few reports on the construction of flexible Li-O 2 batteries. Conventional flexible Li-O 2 batteries possess a loose battery structure, which prevents flexibility and stability. The low mechanical strength of the gas diffusion layer and anode also lead to a flexible Li-O 2 battery with poor mechanical properties. All these attributes limit their practical applications. Herein, the authors develop an integrated flexible Li-O 2 battery based on a high-fatigue-resistance anode and a novel flexible stretchable gas diffusion layer. Owing to the synergistic effect of the stable electrocatalytic activity and hierarchical 3D interconnected network structure of the free-standing cathode, the obtained flexible Li-O 2 batteries exhibit superior electrochemical performance, including a high specific capacity, an excellent rate capability, and exceptional cycle stability. Furthermore, benefitting from the above advantages, the as-fabricated flexible batteries can realize excellent mechanical and electrochemical stability. Even after a thousand cycles of the bending process, the flexible Li-O 2 battery can still possess a stable open-circuit voltage, a high specific capacity, and a durable cycle performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. GaInAs Junction FET with InP buffer layer prepared by selective ion implantation of Be and rapid thermal annealing

    International Nuclear Information System (INIS)

    Selders, J.; Wachs, H.J.; Jurgensen, H.

    1986-01-01

    GaInAs JFETs were fabricated on VPE-grown GaInAs layers. The pn junctions have been realised with Be ion implantation and rapid thermal annealing. The devices show a high transconductance of 130 mS/mm and an electron saturation velocity of 1.8 x 10 7 cm/s. Channel mobilities measured at the complete device are as high as 6800 cm 2 /Vs. These excellent device properties are due to the use of an undoped InP buffer layer which avoids the diffusion of Fe from the substrate into the active layer. The data were supported by S-parameter measurements which gave a frequency limit of 20 GHz for gate dimensions of 1.6 by 200 μm 2 . (author)

  18. N-channel thin-film transistors based on 1,4,5,8-naphthalene tetracarboxylic dianhydride with ultrathin polymer gate buffer layer

    International Nuclear Information System (INIS)

    Tanida, Shinji; Noda, Kei; Kawabata, Hiroshi; Matsushige, Kazumi

    2009-01-01

    N-channel operation of thin-film transistors based on 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTCDA) with a 9-nm-thick poly(methyl methacrylate) (PMMA) gate buffer layer was examined. The uniform coverage of the ultrathin PMMA layer on an SiO 2 gate insulator, verified by X-ray reflectivity measurement, caused the increase of electron field-effect mobility because of the suppression of electron traps existing on the SiO 2 surface. In addition, air stability for n-channel operation of the NTCDA transistor was also improved by the PMMA layer which possibly prevented the adsorption of ambient water molecules onto the SiO 2 surface.

  19. Identification of nano-sized holes by TEM in the graphene layer of graphite and the high rate discharge capability of Li-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Takamura, Tsutomu [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Endo, Koji [Department of Chemistry, Rikkyo University, Tokyo 171-8501 (Japan); Fu, Lijun; Wu, Yuping [Department of Chemistry, Fudan University, Shanghai 200433 (China); Lee, Kyeong Jik [SODIFF Advanced Material Co. Ltd., Yeongju, Geongbuk 750-080 (Korea); Matsumoto, Takatoshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai (Japan)

    2007-12-20

    SEM images of round-shaped natural graphite, currently widely used as the anode active material of Li-ion batteries, show that the surface mainly consists of the basal plane, which suggests that the Li insertion/extraction reaction rate is quite limited. In contrast to this suggestion, however, the anode of commercial Li-ion batteries is capable of high rate charging/discharging. In order to explain this inconsistency, we propose that there are nano-holes in the graphene layers of the graphite allowing Li to be very easily inserted and extracted via the holes. Prior to the measurements a quantum chemical investigation was performed on the energy required for Li to pass through the hole in a graphene layer (E{sub act}). The results showed that the E{sub act} value is too high when the size is smaller than pyrene, but is fairly low for holes of the size of coronene, implying that Li can pass through the basal plane layer if there is a hole larger than coronene. Characterization of the rounded graphite sample and flaky natural graphite was conducted by constant-current charge/discharge cycle tests, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). XRD revealed no appreciable difference between the rounded graphite and flaky natural graphite, in agreement with Raman data. A detailed analysis of the HRTEM results revealed the presence of a number of variously sized circular images. We believe that these are holes in the graphene layer through which Li can pass. The mechanism of formation of the holes is discussed. (author)

  20. High-quality III-nitride films on conductive, transparent (2̅01)-oriented β-Ga2O3 using a GaN buffer layer

    Science.gov (United States)

    Muhammed, M. M.; Roldan, M. A.; Yamashita, Y.; Sahonta, S.-L.; Ajia, I. A.; Iizuka, K.; Kuramata, A.; Humphreys, C. J.; Roqan, I. S.

    2016-07-01

    We demonstrate the high structural and optical properties of InxGa1-xN epilayers (0 ≤ x ≤ 23) grown on conductive and transparent (01)-oriented β-Ga2O3 substrates using a low-temperature GaN buffer layer rather than AlN buffer layer, which enhances the quality and stability of the crystals compared to those grown on (100)-oriented β-Ga2O3. Raman maps show that the 2″ wafer is relaxed and uniform. Transmission electron microscopy (TEM) reveals that the dislocation density reduces considerably (~4.8 × 107 cm-2) at the grain centers. High-resolution TEM analysis demonstrates that most dislocations emerge at an angle with respect to the c-axis, whereas dislocations of the opposite phase form a loop and annihilate each other. The dislocation behavior is due to irregular (01) β-Ga2O3 surface at the interface and distorted buffer layer, followed by relaxed GaN epilayer. Photoluminescence results confirm high optical quality and time-resolved spectroscopy shows that the recombination is governed by bound excitons. We find that a low root-mean-square average (≤1.5 nm) of InxGa1-xN epilayers can be achieved with high optical quality of InxGa1-xN epilayers. We reveal that (01)-oriented β-Ga2O3 substrate has a strong potential for use in large-scale high-quality vertical light emitting device design.

  1. High-quality III-nitride films on conductive, transparent (2̅01)-oriented β-Ga2O3 using a GaN buffer layer

    KAUST Repository

    Mumthaz Muhammed, Mufasila

    2016-07-14

    We demonstrate the high structural and optical properties of InxGa1−xN epilayers (0 ≤ x ≤ 23) grown on conductive and transparent (01)-oriented β-Ga2O3 substrates using a low-temperature GaN buffer layer rather than AlN buffer layer, which enhances the quality and stability of the crystals compared to those grown on (100)-oriented β-Ga2O3. Raman maps show that the 2″ wafer is relaxed and uniform. Transmission electron microscopy (TEM) reveals that the dislocation density reduces considerably (~4.8 × 107 cm−2) at the grain centers. High-resolution TEM analysis demonstrates that most dislocations emerge at an angle with respect to the c-axis, whereas dislocations of the opposite phase form a loop and annihilate each other. The dislocation behavior is due to irregular (01) β-Ga2O3 surface at the interface and distorted buffer layer, followed by relaxed GaN epilayer. Photoluminescence results confirm high optical quality and time-resolved spectroscopy shows that the recombination is governed by bound excitons. We find that a low root-mean-square average (≤1.5 nm) of InxGa1−xN epilayers can be achieved with high optical quality of InxGa1−xN epilayers. We reveal that (01)-oriented β-Ga2O3 substrate has a strong potential for use in large-scale high-quality vertical light emitting device design.

  2. Characterization of polycrystalline silicon-oxide-nitride-oxide-silicon devices on a SiO2 or Si3N4 buffer layer

    Science.gov (United States)

    Lee, Sang-Youl; Oh, Jae-Sub; Yang, Seung-Dong; Yun, Ho-Jin; Jeong, Kwang-Seok; Kim, Yu-Mi; Lee, Hi-Deok; Lee, Ga-Won

    2013-10-01

    Silicon-oxide-nitride-oxide-silicon (SONOS) memory devices were fabricated from polycrystalline silicon (poly-Si) using the solid phase crystallization (SPC) method for use in a low-power system-on-panel (SOP) display. In these poly-Si SONOS memories, oxide or nitride was used as a buffer layer. The electrical characteristics, such as the threshold voltage ( V T ), subthreshold slope ( SS) and transconductance ( g m ), were determined for each SONOS device. To interpret the characteristics of both poly-Si devices, x-ray diffraction (XRD) measurements and flicker noise analysis were conducted. The results show that the poly-Si SONOS on the oxide layer has better electrical, memory characteristics, such as turn-on speed and g m , program/erase, endurance and data retention than that on the nitride layer. From the XRD measurements, it is shown that the grain size of the poly-Si on the oxide layer is larger than that on the nitride layer. From the flicker noise analysis, the poly-Si device on oxide was shown to have less traps or defects in the channel layer than that on nitride.

  3. Deposition temperature induced conduction band changes in zinc tin oxide buffer layers for Cu(In,Ga)Se2 solar cells

    OpenAIRE

    Lindahl, Johan; Keller, Jan; Donzel-Gargand, Olivier; Szaniawski, Piotr; Edoff, Marika; Törndahl, Tobias

    2016-01-01

    Thin film Cu(In,Ga)Se2 solar cells with ALD-deposited Zn1-xSnxOy buffer layers were fabricated and the solar cell properties were investigated for varying ALD deposition temperatures in the range from 90 °C up to 180 °C. It was found that a process window exists between 105 °C and 135 °C, where high solar cell efficiency can be achieved. At lower ALD deposition temperatures the solar cell performance was mainly limited by low fill factor and at higher temperatures by low open circuit voltage....

  4. Characteristics of the epitaxy of InGaN-based light-emitting diodes grown by nanoscale epitaxial lateral overgrowth using a nitrided titanium buffer layer

    International Nuclear Information System (INIS)

    Shieh, Chen-Yu; Li, Zhen-Yu; Chang, Jenq-Yang; Chi, Gou-Chung

    2015-01-01

    In this work, a buffer layer of nitrided titanium (Ti) achieved through the nitridation of a Ti metal layer on a sapphire substrate was used for the epitaxial growth of InGaN-based light-emitting diodes (LEDs) achieved by low pressure metal-organic chemical vapor deposition. The effect of in-situ Ti metal nitridation on the performance of these InGaN-based LEDs was then investigated. It was very clear that the use of the nitrided Ti buffer layer (NTBL) induced the formation of a nanoscale epitaxial lateral overgrowth layer during the epitaxial growth. When evaluated by Raman spectroscopy, this epi-layer exhibited large in-plane compressive stress releasing with a Raman shift value of 567.9 cm -1 . Cathodoluminescence spectroscopy and transmission electron microscopy results indicated that the InGaN-based LEDs with an NTBL have improved crystal quality, with a low threading dislocations density being yielded via the strain relaxation in the InGaN-based LEDs. Based on the results mentioned above, the electroluminescence results indicate that the light performance of InGaN-based LEDs with an NTBL can be enhanced by 45% and 42% at 20 mA and 100 mA, respectively. These results suggest that the strain relaxation and quality improvement in the GaN epilayer could be responsible for the enhancement of emission power. - Highlights: • The crystal-quality of InGaN-based LEDs with NTBL by NELOG was improved. • The InGaN-based LEDs with NTBL have strain releases by NELOG. • The optical properties of InGaN-based LEDs were shown by CL and EL measurements

  5. Controllable synthesis of graphene sheets with different numbers of layers and effect of the number of graphene layers on the specific capacity of anode material in lithium-ion batteries

    International Nuclear Information System (INIS)

    Tong, Xin; Wang, Hui; Wang, Gang; Wan, Lijuan; Ren, Zhaoyu; Bai, Jintao; Bai, Jinbo

    2011-01-01

    High quality graphene sheets are synthesized through efficient oxidation process followed by rapid thermal expansion and reduction by H 2 . The number of graphene layers is controlled by tuning the oxidation degree of GOs. The higher the oxidation degree of GOs is getting, the fewer the numbers of graphene layers can be obtained. The material is characterized by elemental analysis, thermo-gravimetric analysis, scanning electron microscopy, atomic force microscopy, transmission electron microscopy and Fourier transform infrared spectroscopies. The obtained graphene sheets with single, triple and quintuplicate layers as anode materials exhibit a high reversible capacity of 1175, 1007, and 842 mA h g -1 , respectively, which show that the graphene sheets with fewer layers have higher reversible capacity. -- Graphical abstract: The typical TEM images of the graphene sheets derived from GO3(a), GO2(b) and GO1(c). Display Omitted Highlights: → With the oxidation degree of GO increasing, the numbers of graphene layers decreased. → With the numbers of graphene layers decreasing, the reversible capacity improved. → Graphene sheets with single-layer exhibit the best electrochemical performances.

  6. Cadmium free high efficiency Cu2ZnSn(S,Se4 solar cell with Zn1−xSnxOy buffer layer

    Directory of Open Access Journals (Sweden)

    Md. Asaduzzaman

    2017-06-01

    Full Text Available We have investigated the simulation approach of a one-dimensional online simulator named A Device Emulation Program and Tool (ADEPT2.1 and the device performances of a thin film solar cell based on Cu2ZnSn(S,Se4 (CZTSSe absorber have been measured. Initiating with a thin film photovoltaic device structure consisting of n-ZnO:Al/i-ZnO/Zn1-xSnxOy (ZTO/CZTSSe/Mo/SLG stack, a graded space charge region (SCR and an inverted surface layer (ISL were inserted between the buffer and the absorber. The cadmium (Cd free ZTO buffer, a competitive substitute to the CdS buffer, significantly contributes to improve the open-circuit voltage, Voc without deteriorating the short-circuit current density, Jsc. The optimized solar cell performance parameters including Voc, Jsc, fill factor (FF, and efficiency (η were calculated from the current density-voltage curve, also known as J–V characteristic curve. The FF was determined as 73.17%, which in turns, yields a higher energy conversion efficiency of 14.09%.

  7. Improvement of electron mobility in La:BaSnO3 thin films by insertion of an atomically flat insulating (Sr,Ba)SnO3 buffer layer

    Science.gov (United States)

    Shiogai, Junichi; Nishihara, Kazuki; Sato, Kazuhisa; Tsukazaki, Atsushi

    2016-06-01

    One perovskite oxide, ASnO3 (A = Sr, Ba), is a candidate for use as a transparent conductive oxide with high electron mobility in single crystalline form. However, the electron mobility of films grown on SrTiO3 substrates does not reach the bulk value, probably because of dislocation scattering that originates from the large lattice mismatch. This study investigates the effect of insertion of bilayer BaSnO3 / (Sr,Ba)SnO3 for buffering this large lattice mismatch between La:BaSnO3 and SrTiO3 substrate. The insertion of 200-nm-thick BaSnO3 on (Sr,Ba)SnO3 bilayer buffer structures reduces the number of dislocations and improves surface smoothness of the films after annealing as proved respectively by scanning transmission electron microscopy and atomic force microscopy. A systematic investigation of BaSnO3 buffer layer thickness dependence on Hall mobility of the electron transport in La:BaSnO3 shows that the highest obtained value of mobility is 78 cm2V-1s-1 because of its fewer dislocations. High electron mobility films based on perovskite BaSnO3 can provide a good platform for transparent-conducting-oxide electronic devices and for creation of fascinating perovskite heterostructures.

  8. Improvement of electron mobility in La:BaSnO3 thin films by insertion of an atomically flat insulating (Sr,BaSnO3 buffer layer

    Directory of Open Access Journals (Sweden)

    Junichi Shiogai

    2016-06-01

    Full Text Available One perovskite oxide, ASnO3 (A = Sr, Ba, is a candidate for use as a transparent conductive oxide with high electron mobility in single crystalline form. However, the electron mobility of films grown on SrTiO3 substrates does not reach the bulk value, probably because of dislocation scattering that originates from the large lattice mismatch. This study investigates the effect of insertion of bilayer BaSnO3 / (Sr,BaSnO3 for buffering this large lattice mismatch between La:BaSnO3 and SrTiO3 substrate. The insertion of 200-nm-thick BaSnO3 on (Sr,BaSnO3 bilayer buffer structures reduces the number of dislocations and improves surface smoothness of the films after annealing as proved respectively by scanning transmission electron microscopy and atomic force microscopy. A systematic investigation of BaSnO3 buffer layer thickness dependence on Hall mobility of the electron transport in La:BaSnO3 shows that the highest obtained value of mobility is 78 cm2V−1s−1 because of its fewer dislocations. High electron mobility films based on perovskite BaSnO3 can provide a good platform for transparent-conducting-oxide electronic devices and for creation of fascinating perovskite heterostructures.

  9. Suppression of short channel effects in FinFETs using crystalline ZrO2 high-K/Al2O3 buffer layer gate stack for low power device applications

    Science.gov (United States)

    Tsai, Meng-Chen; Wang, Chin-I.; Chen, Yen-Chang; Chen, Yi-Ju; Li, Kai-Shin; Chen, Min-Cheng; Chen, Miin-Jang

    2018-03-01

    The electrical characteristics of FinFETs with a crystalline ZrO2/Al2O3 buffer layer gate stack and a crystalline ZrO2 high-K dielectric single layer, along with different fin widths and gate lengths, are investigated. Compared with the FinFETs with a single layer of crystalline ZrO2 high-K dielectric, the gate stack comprising the crystalline ZrO2/Al2O3 buffer layer on FinFETs leads to the suppression of short channel effects in terms of a low drain induced barrier lowering, reduced threshold voltage roll-off, and improved subthreshold swing. The ON/OFF current ratio and gate leakage current of FinFETs are also improved by the crystalline ZrO2/Al2O3 buffer layer gate stack. The improvement of electrical characteristics is ascribed to the reduced interface state density and gate leakage as a result of the insertion of an Al2O3 buffer layer between ZrO2 and Si. The results demonstrate that the crystalline ZrO2/Al2O3 buffer layer structure is a promising high-K gate stack for next-generation nanoscale transistors.

  10. Scalable Synthesis of Few-Layer MoS2 Incorporated into Hierarchical Porous Carbon Nanosheets for High-Performance Li- and Na-Ion Battery Anodes.

    Science.gov (United States)

    Park, Seung-Keun; Lee, Jeongyeon; Bong, Sungyool; Jang, Byungchul; Seong, Kwang-Dong; Piao, Yuanzhe

    2016-08-03

    It is still a challenging task to develop a facile and scalable process to synthesize porous hybrid materials with high electrochemical performance. Herein, a scalable strategy is developed for the synthesis of few-layer MoS2 incorporated into hierarchical porous carbon (MHPC) nanosheet composites as anode materials for both Li- (LIB) and Na-ion battery (SIB). An inexpensive oleylamine (OA) is introduced to not only serve as a hinder the stacking of MoS2 nanosheets but also to provide a conductive carbon, allowing large scale production. In addition, a SiO2 template is adopted to direct the growth of both carbon and MoS2 nanosheets, resulting in the formation of hierarchical porous structures with interconnected networks. Due to these unique features, the as-obtained MHPC shows substantial reversible capacity and very long cycling performance when used as an anode material for LIBs and SIBs, even at high current density. Indeed, this material delivers reversible capacities of 732 and 280 mA h g(-1) after 300 cycles at 1 A g(-1) in LIBs and SIBs, respectively. The results suggest that these MHPC composites also have tremendous potential for applications in other fields.

  11. Improving the Energy Efficiency of Direct Formate Fuel Cells with a Pd/C-CeO2 Anode Catalyst and Anion Exchange Ionomer in the Catalyst Layer

    Directory of Open Access Journals (Sweden)

    Hamish Andrew Miller

    2018-02-01

    Full Text Available This article describes the development of a high power density Direct Formate Fuel Cell (DFFC fed with potassium formate (KCOOH. The membrane electrode assembly (MEA contains no platinum metal. The cathode catalyst is FeCo/C combined with a commercial anion exchange membrane (AEM. To enhance the power output and energy efficiency we have employed a nanostructured Pd/C-CeO2 anode catalyst. The activity for the formate oxidation reaction (FOR is enhanced when compared to a Pd/C catalyst with the same Pd loading. Fuel cell tests at 60 °C show a peak power density of almost 250 mW cm−2. The discharge energy (14 kJ, faradic efficiency (89% and energy efficiency (46% were determined for a single fuel charge (30 mL of 4 M KCOOH and 4 M KOH. Energy analysis demonstrates that removal of the expensive KOH electrolyte is essential for the future development of these devices. To compensate we apply for the first time a polymeric ionomer in the catalyst layer of the anode electrode. A homopolymer is synthesized by the radical polymerization of vinyl benzene chloride followed by amination with 1,4-diazabicyclo[2.2.2]octane (DABCO. The energy delivered, energy efficiency and fuel consumption efficiency of DFFCs fed with 4 M KCOOH are doubled with the use of the ionomer.

  12. Fabrication of porous carbon sphere@SnO2@carbon layer coating composite as high performance anode for sodium-ion batteries

    Science.gov (United States)

    Li, Xin; Sun, Xiaohong; Gao, Zhiwen; Hu, Xudong; Guo, Jingdong; Cai, Shu; Guo, Ruisong; Ji, Huiming; Zheng, Chunming; Hu, Wenbin

    2018-03-01

    SnO2 has triggered lots of research efforts as anode for sodium-ion batteries. However, the volume expansion and poor conductivity lead to an unsatisfactory electrochemical performance for the practical application of SnO2. In this work, a novel carbon-coated SnO2 supported by porous carbon sphere composite is synthesized by hydrothermal process combining with annealing method. The porous carbon sphere@SnO2@carbon layer coating composite anode delivers a reversible capacity of 326 mAh g-1 over 80 cycles at a current density of 50 mA g-1. Even at 1600 mA g-1, a capacity of 82 mAh g-1 is still maintained after 550 cycles. Such excellent performance can be ascribed to the unique structure, which efficiently accommodates volume expansion, enhances conductivity and offers shortened sodium-ion transport pathway. The charge-storage mechanisms can be comprised of diffusion-controlled reaction and pseudocapacitance effect. At high scan rate of 1.0 mV s-1, the capacity contribution of pseudocapacitance effect could reach as high as 78%.

  13. Characterization of Sulfur Bonding in CdS:O Buffer Layers for CdTe-based Thin-Film Solar Cells.

    Science.gov (United States)

    Duncan, Douglas A; Kephart, Jason M; Horsley, Kimberly; Blum, Monika; Mezher, Michelle; Weinhardt, Lothar; Häming, Marc; Wilks, Regan G; Hofmann, Timo; Yang, Wanli; Bär, Marcus; Sampath, Walajabad S; Heske, Clemens

    2015-08-05

    On the basis of a combination of X-ray photoelectron spectroscopy and synchrotron-based X-ray emission spectroscopy, we present a detailed characterization of the chemical structure of CdS:O thin films that can be employed as a substitute for CdS layers in thin-film solar cells. It is possible to analyze the local chemical environment of the probed elements, in particular sulfur, hence allowing insights into the species-specific composition of the films and their surfaces. A detailed quantification of the observed sulfur environments (i.e., sulfide, sulfate, and an intermediate oxide) as a function of oxygen content is presented, allowing a deliberate optimization of CdS:O thin films for their use as alternative buffer layers in thin-film photovoltaic devices.

  14. Epitaxial integration of CoFe2O4 thin films on Si (001) surfaces using TiN buffer layers

    Science.gov (United States)

    Prieto, Pilar; Marco, José F.; Prieto, José E.; Ruiz-Gomez, Sandra; Perez, Lucas; del Real, Rafael P.; Vázquez, Manuel; de la Figuera, Juan

    2018-04-01

    Epitaxial cobalt ferrite thin films with strong in-plane magnetic anisotropy have been grown on Si (001) substrates using a TiN buffer layer. The epitaxial films have been grown by ion beam sputtering using either metallic, CoFe2, or ceramic, CoFe2O4, targets. X-ray diffraction (XRD) and Rutherford spectrometry (RBS) in random and channeling configuration have been used to determine the epitaxial relationship CoFe2O4 [100]/TiN [100]/Si [100]. Mössbauer spectroscopy, in combination with XRD and RBS, has been used to determine the composition and structure of the cobalt ferrite thin films. The TiN buffer layer induces a compressive strain in the cobalt ferrite thin films giving rise to an in-plane magnetic anisotropy. The degree of in-plane anisotropy depends on the lattice mismatch between CoFe2O4 and TiN, which is larger for CoFe2O4 thin films grown on the reactive sputtering process with ceramic targets.

  15. Tuning the Phase and Microstructural Properties of TiO2 Films Through Pulsed Laser Deposition and Exploring Their Role as Buffer Layers for Conductive Films

    Science.gov (United States)

    Agarwal, S.; Haseman, M. S.; Leedy, K. D.; Winarski, D. J.; Saadatkia, P.; Doyle, E.; Zhang, L.; Dang, T.; Vasilyev, V. S.; Selim, F. A.

    2018-04-01

    Titanium oxide (TiO2) is a semiconducting oxide of increasing interest due to its chemical and thermal stability and broad applicability. In this study, thin films of TiO2 were deposited by pulsed laser deposition on sapphire and silicon substrates under various growth conditions, and characterized by x-ray diffraction (XRD), atomic force microscopy (AFM), optical absorption spectroscopy and Hall-effect measurements. XRD patterns revealed that a sapphire substrate is more suitable for the formation of the rutile phase in TiO2, while a silicon substrate yields a pure anatase phase, even at high-temperature growth. AFM images showed that the rutile TiO2 films grown at 805°C on a sapphire substrate have a smoother surface than anatase films grown at 620°C. Optical absorption spectra confirmed the band gap energy of 3.08 eV for the rutile phase and 3.29 eV for the anatase phase. All the deposited films exhibited the usual high resistivity of TiO2; however, when employed as a buffer layer, anatase TiO2 deposited on sapphire significantly improves the conductivity of indium gallium zinc oxide thin films. The study illustrates how to control the formation of TiO2 phases and reveals another interesting application for TiO2 as a buffer layer for transparent conducting oxides.

  16. Prominent electric properties of BiFeO₃ shells sputtered on ZnO-nanorod cores with LaNiO₃ buffer layers.

    Science.gov (United States)

    Chiu, Kuan-Chang; Yang, Tung-Han; Wu, Jenn-Ming

    2013-06-07

    In this work, template-assisted methods were adopted to grow BiFeO3 (BFO)-nanorod arrays on substrates. Well-aligned ZnO-nanorod arrays (ZNAs) grown hydrothermally were chosen as positive templates. It was found that perovskite BFO could not be radio frequency (RF)-magnetron sputtered directly on a ZNA at elevated temperatures. Only amorphous BFO was obtained. However, polycrystalline BFO shells could be fabricated by RF-magnetron sputtering on ZNA templates by the introduction of LaNiO3 (LNO) buffer layers. The LNO buffer layer deposited on the ZNA by RF-magnetron sputtering was demonstrated to improve the adhesion and crystallization of the sequentially sputtered BFO shells. The electrical properties were evaluated by conductive atomic force microscopy and piezoresponse force microscopy. Bulk-limited Poole-Frenkel emission dominates the conduction of BFO shells at positive bias, while barrier-limited Schottky emission accounts for the conduction at negative bias due to the interface between the Pt/Ir-coated tip and the BFO. The piezoelectric coefficient (d33) was estimated to be ∼32.93 pm V(-1) and a polarization of 133 μC cm(-2) was derived. These values are higher than those reported previously for BFO films.

  17. Prominent electric properties of BiFeO3 shells sputtered on ZnO-nanorod cores with LaNiO3 buffer layers

    Science.gov (United States)

    Chiu, Kuan-Chang; Yang, Tung-Han; Wu, Jenn-Ming

    2013-06-01

    In this work, template-assisted methods were adopted to grow BiFeO3 (BFO)-nanorod arrays on substrates. Well-aligned ZnO-nanorod arrays (ZNAs) grown hydrothermally were chosen as positive templates. It was found that perovskite BFO could not be radio frequency (RF)-magnetron sputtered directly on a ZNA at elevated temperatures. Only amorphous BFO was obtained. However, polycrystalline BFO shells could be fabricated by RF-magnetron sputtering on ZNA templates by the introduction of LaNiO3 (LNO) buffer layers. The LNO buffer layer deposited on the ZNA by RF-magnetron sputtering was demonstrated to improve the adhesion and crystallization of the sequentially sputtered BFO shells. The electrical properties were evaluated by conductive atomic force microscopy and piezoresponse force microscopy. Bulk-limited Poole-Frenkel emission dominates the conduction of BFO shells at positive bias, while barrier-limited Schottky emission accounts for the conduction at negative bias due to the interface between the Pt/Ir-coated tip and the BFO. The piezoelectric coefficient (d33) was estimated to be ˜32.93 pm V-1 and a polarization of 133 μC cm-2 was derived. These values are higher than those reported previously for BFO films.

  18. High dielectric constant and energy density induced by the tunable TiO2 interfacial buffer layer in PVDF nanocomposite contained with core-shell structured TiO2@BaTiO3 nanoparticles

    Science.gov (United States)

    Hu, Penghao; Jia, Zhuye; Shen, Zhonghui; Wang, Peng; Liu, Xiaoru

    2018-05-01

    To realize application in high-capacity capacitors and portable electric devices, large energy density is eagerly desired for polymer-based nanocomposite. The core-shell structured nanofillers with inorganic buffer layer are recently supposed to be promising in improving the dielectric property of polymer nanocomposite. In this work, core-shell structured TO@BT nanoparticles with crystalline TiO2 buffer layer coated on BaTiO3 nanoparticle were fabricated via solution method and heat treatment. The thickness of the TO buffer layer can be tailored by modulating the additive amount of the titanate coupling agent in preparation process, and the apparent dielectric properties of nanocomposite are much related to the thickness of the TO layer. The relatively thin TO layer prefer to generate high polarization to increase dielectric constant while the relatively thick TO layer would rather to homogenize field to maintain breakdown strength. Simulation of electric field distribution in the interfacial region reveals the improving effect of the TO buffer layer on the dielectric properties of nanocomposite which accords with the experimental results well. The optimized nanoparticle TO@BT-2 with a mean thickness of 3-5 nm buffer layer of TO is effective in increasing both the ε and Eb in the PVDF composite film. The maximal discharged energy density of 8.78 J/cm3 with high energy efficiency above 0.6 is obtained in TO@BT-2/PVDF nanocomposite with 2.5 vol% loading close to the breakdown strength of 380 kV/mm. The present study demonstrates the approach to optimize the structure of core-shell nanoparticles by modulating buffer layer and provides a new way to further enlarge energy density in polymer nanocomposite.

  19. Two-dimensional layered compound based anode materials for lithium-ion batteries and sodium-ion batteries.

    Science.gov (United States)

    Xie, Xiuqiang; Wang, Shijian; Kretschmer, Katja; Wang, Guoxiu

    2017-08-01

    Rechargeable batteries, such as lithium-ion and sodium-ion batteries, have been considered as promising energy conversion and storage devices with applications ranging from small portable electronics, medium-sized power sources for electromobility, to large-scale grid energy storage systems. Wide implementations of these rechargeable batteries require the development of electrode materials that can provide higher storage capacities than current commercial battery systems. Within this greater context, this review will present recent progresses in the development of the 2D material as anode materials for battery applications represented by studies conducted on graphene, molybdenum disulfide, and MXenes. This review will also discuss remaining challenges and future perspectives of 2D materials in regards to a full utilization of their unique properties and interactions with other battery components. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Dose rate hardening of As Ga components by buffer layers with hetero structure Ga As/Ga Al As

    International Nuclear Information System (INIS)

    Dupont-Nivet, E.; Coic, Y.M.; Frijlink, P.; Nicolas, J.L.

    1989-01-01

    Radiation resistance of gallium arsenide components is improved by incorporation between the substrate and the active layer a potential barrier with GaAlAs which has a greater forbidden band than GaAs [fr

  1. Inkjet printing of multiple Ce{sub 0.8}Gd{sub 0.2}O{sub 2} buffer layers on a Ni-5%W substrate

    Energy Technology Data Exchange (ETDEWEB)

    Mosiadz, M; Tomov, R I; Hopkins, S C; Glowacki, B A [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Martin, G [Inkjet Research Centre, Institute for Manufacturing, Department of Engineering, University of Cambridge, Mill Lane, Cambridge, CB2 1RX (United Kingdom); Holzapfel, B, E-mail: mm701@cam.ac.u [Superconducting Materials, Institute for Metallic Materials, Leibnitz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany)

    2010-06-01

    The successful inkjet printing of multiple cerium gadolinium oxide (Ce{sub 0.8}Gd{sub 0.2}O{sub 2}) layers on highly textured Ni-5%W is reported using a stable ink, developing a solid-liquid interface comparable with that arising from dip coating. Two different approaches were used for the deposition of CGO layers using a 16-nozzle piezoelectric drop-on-demand print head. Two overlapping square arrays of droplets with constant volume and spacing were printed, with and without an intermediate CGO crystallization. The shortest possible heat treatment of the deposited layers was applied, potentially suitable for continuous large scale production. The results from X-ray diffraction show that the single phase Ce{sub 0.8}Gd{sub 0.2}O{sub 2} was obtained in all cases, but only the approach with intermediate CGO crystallization can produce a highly textured buffer layer. Optical micrographs and atomic force microscopy (AFM) also indicate the good quality of deposited films after heat treatment.

  2. Design of high breakdown voltage GaN vertical HFETs with p-GaN buried buffer layers for power switching applications

    Science.gov (United States)

    Du, Jiangfeng; Liu, Dong; Zhao, Ziqi; Bai, Zhiyuan; Li, Liang; Mo, Jianghui; Yu, Qi

    2015-07-01

    To achieve a high breakdown voltage, a GaN vertical heterostructure field effect transistor with p-GaN buried layers (PBL-VHFET) is proposed in this paper. The breakdown voltage of this GaN-based PBL-VHFET could be improved significantly by the optimizing thickness of p-GaN buried layers and doping concentration in PBL. When the GaN buffer layer thickness is 15 μm, the thickness, length and p-doping concentration of PBL are 0.3 μm, 2.7 μm, and 3 × 1017 cm-3, respectively. Simulation results show that the breakdown voltage and on-resistance of the device with two p-GaN buried layers are 3022 V and 3.13 mΩ cm2, respectively. The average breakdown electric field would reach as high as 201.5 V/μm. Compared with the typical GaN vertical heterostructure FETs without PBL, both of breakdown voltage and average breakdown electric field of device are increased more than 50%.

  3. Influence of Weak Base Addition to Hole-Collecting Buffer Layers in Polymer:Fullerene Solar Cells

    Directory of Open Access Journals (Sweden)

    Jooyeok Seo

    2017-02-01

    Full Text Available We report the effect of weak base addition to acidic polymer hole-collecting layers in normal-type polymer:fullerene solar cells. Varying amounts of the weak base aniline (AN were added to solutions of poly(3,4-ethylenedioxythiophene:poly(styrenesulfonate (PEDOT:PSS. The acidity of the aniline-added PEDOT:PSS solutions gradually decreased from pH = 1.74 (AN = 0 mol% to pH = 4.24 (AN = 1.8 mol %. The electrical conductivity of the PEDOT:PSS-AN films did not change much with the pH value, while the ratio of conductivity between out-of-plane and in-plane directions was dependent on the pH of solutions. The highest power conversion efficiency (PCE was obtained at pH = 2.52, even though all devices with the PEDOT:PSS-AN layers exhibited better PCE than those with the pristine PEDOT:PSS layers. Atomic force microscopy investigation revealed that the size of PEDOT:PSS domains became smaller as the pH increased. The stability test for 100 h illumination under one sun condition disclosed that the PCE decay was relatively slower for the devices with the PEDOT:PSS-AN layers than for those with pristine PEDOT:PSS layers.

  4. 5-nm LiF as an Efficient Cathode Buffer Layer in Polymer Solar Cells Through Simply Introducing a C60 Interlayer

    Science.gov (United States)

    Liu, Xiaodong; Guo, L. Jay; Zheng, Yonghao

    2017-09-01

    Lithium fluoride (LiF) is an efficient and widely used cathode buffer layer (CBL) in bulk heterojunction polymer solar cells (PSCs). The LiF thickness is normally limited to 1 nm due to its insulting property. Such small thickness is difficult to precise control during thermal deposition, and more importantly, 1-nm-thick LiF cannot provide sufficient protection for the underlying active layer. Herein, we demonstrated the application of a very thick LiF as CBL without sacrificing the device efficiency by simply inserting a C60 layer between the active layer and LiF layer. The devices with the C60/LiF (5 nm) double CBLs exhibit a peak power conversion efficiency (PCE) of 3.65%, which is twofold higher than that (1.79%) of LiF (5 nm)-only device. The superior performance of the C60/LiF (5 nm)-based devices is mainly attributed to the good electrical conductivity of the C60/LiF (5 nm) bilayer, arising from the intermixing occurred at the C60/LiF interface. Besides, the formation of a P3HT/C60 subcell and the optical spacer effect of C60 also contribute to the increase in short-circuit current density ( J sc) of the device. With further increase of LiF thickness to 8 nm, a PCE of 1.10% is attained for the C60/LiF-based device, while the negligible photovoltaic performance is observed for the LiF-only device. All in all, our results show that C60/LiF bilayer is a promising alternative to LiF single layer due to its high tolerance to the LiF thickness variations.

  5. Process for anodizing aluminum foil

    International Nuclear Information System (INIS)

    Ball, J.A.; Scott, J.W.

    1984-01-01

    In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 80 0 C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V

  6. Electrochemical behaviour of silver in borate buffer solutions

    International Nuclear Information System (INIS)

    Zaky, Ayman M.; Assaf, Fawzi H.; Abd El Rehim, Sayed S.; Mohamed, Basheer

    2004-01-01

    The electrochemical behaviour of Ag in aqueous 0.15 M borax and 0.15 M boric acid buffer solution was studied under various conditions using cyclic voltammetry and potentiostatic techniques. It was found that the anodic polarization curve of Ag in borate buffer solution was characterized by the appearance of two potential regions, active and passive, prior to the oxygen evolution reaction. The active potential region was characterized by the appearance of three anodic peaks, the first two peaks A 1 and A 2 correspond to the oxidation of Ag and formation of [Ag(OH) 2 ] - soluble compound and a passive film of Ag 2 O on the electrode surface. The third anodic peak corresponds to the conversion of both [Ag(OH) 2 ] - and Ag 2 O to Ag 2 O 2 . X-ray diffraction patterns confirmed the existence of Ag 2 O and Ag 2 O 2 passive layers on the electrode surface potentiodynamically polarized up to 800 mV. Potentiostatic current transient measurements showed that the formation of Ag 2 O and Ag 2 O 2 involves a nucleation and growth mechanism under diffusion control

  7. Quantum and conversion efficiencies optimization of superstrate CIGS thin-films solar cells using In2Se3 buffer layer

    Science.gov (United States)

    Bouchama, Idris; Boudour, Samah; Bouarissa, Nadir; Rouabah, Zahir

    2017-10-01

    In this present contribution, AMPS-1D device simulator is employed to study the performances of superstrate SLG/TCO/p-Cu(In,Ga)Se2(CIGS)/n-ODC/n-In2Se3/Metal thin film solar cells. The impact of the TCO and Metal work functions on the cell performance has been investigated. The combination of optical transparency and electrical property for TCO front contact layer is found to yield high efficiency. The obtained results show that the TCO work function should be large enough to achieve high conversion efficiency for superstrate CIGS solar cell. Nevertheless, it is desirable for Metal back contact layer to have low work function to prevent the effect of band bending in the n-In2Se3/Metal interface. Several TCOs materials and metals have been tested respectively as a front and back contact layers for superstrate CIGS solar cells. An efficiency of 20.18%, with Voc ≈ 0.71 V, Jsc ≈ 35.36 mA/cm2 and FF ≈ 80.42%, has been achieved with ZnSn2O3-based as TCO front contact layer. In the case of SnO2:F front contact and indium back contact layers, an efficiency of 16.31%, with Voc ≈ 0.64 V, Jsc ≈ 31.4 mA/cm2 and FF ≈ 79.4%, has been obtained. The present results of simulation suggest an improvement of superstrate CIGS solar cells efficiency for feasible fabrication.

  8. Simulation for silicon-compatible InGaAs-based junctionless field-effect transistor using InP buffer layer

    Science.gov (United States)

    Seo, Jae Hwa; Cho, Seongjae; Kang, In Man

    2013-10-01

    In this paper, we present the optimized performances of indium gallium arsenide (InGaAs)-based compound junctionless field-effect transistors (JLFETs) using an indium phosphide (InP) buffer layer. The proposed InGaAs-InP material combination with little lattice mismatch provides a significant improvement in current drivability securing various potential applications. Device optimization is performed in terms of primary dc parameters and characterization is investigated by two-dimensional (2D) technology computer-aided design simulations. The optimization variables were the channel doping concentration (Nch), the buffer doping concentration (Nbf), and the channel thickness (Tch). For the optimally designed InGaAs JLFET, on-state current (Ion) of 325 µA µm-1, subthreshold swing (S) of 80 mV dec-1, and current ratio (Ion/Ioff) of 109 were obtained. In the end, the results are compared with the data of silicon (Si)-based JL MOSFETs to confirm the improvements.

  9. Design considerations for λ ˜ 3.0- to 3.5-μm-emitting quantum cascade lasers on metamorphic buffer layers

    Science.gov (United States)

    Rajeev, Ayushi; Sigler, Chris; Earles, Tom; Flores, Yuri V.; Mawst, Luke J.; Botez, Dan

    2018-01-01

    Quantum cascade lasers (QCLs) that employ metamorphic buffer layers as substrates of variable lattice constant have been designed for emission in the 3.0- to 3.5-μm wavelength range. Theoretical analysis of the active-region (AR) energy band structure, while using an 8-band k•p model, reveals that one can achieve both effective carrier-leakage suppression as well as fast carrier extraction in QCL structures of relatively low strain. Significantly lower indium-content quantum wells (QWs) can be employed for the AR compared to QWs employed for conventional short-wavelength QCL structures grown on InP, which, in turn, is expected to eliminate carrier leakage to indirect-gap valleys (X, L). An analysis of thermo-optical characteristics for the complete device design indicates that high-Al-content AlInAs cladding layers are more effective for both optical confinement and thermal dissipation than InGaP cladding layers. An electroluminescence-spectrum full-width half-maximum linewidth of 54.6 meV is estimated from interface roughness scattering and, by considering both inelastic and elastic scattering, the threshold-current density for 3.39-μm-emitting, 3-mm-long back-facet-coated QCLs is projected to be 1.40 kA/cm2.

  10. Ultrathin Nitrogen-Doped Carbon Layer Uniformly Supported on Graphene Frameworks as Ultrahigh-Capacity Anode for Lithium-Ion Full Battery.

    Science.gov (United States)

    Huang, Yanshan; Li, Ke; Yang, Guanhui; Aboud, Mohamed F Aly; Shakir, Imran; Xu, Yuxi

    2018-01-24

    The designable structure with 3D structure, ultrathin 2D nanosheets, and heteroatom doping are considered as highly promising routes to improve the electrochemical performance of carbon materials as anodes for lithium-ion batteries. However, it remains a significant challenge to efficiently integrate 3D interconnected porous frameworks with 2D tunable heteroatom-doped ultrathin carbon layers to further boost the performance. Herein, a novel nanostructure consisting of a uniform ultrathin N-doped carbon layer in situ coated on a 3D graphene framework (NC@GF) through solvothermal self-assembly/polymerization and pyrolysis is reported. The NC@GF with the nanosheets thickness of 4.0 nm and N content of 4.13 at% exhibits an ultrahigh reversible capacity of 2018 mA h g -1 at 0.5 A g -1 and an ultrafast charge-discharge feature with a remarkable capacity of 340 mA h g -1 at an ultrahigh current density of 40 A g -1 and a superlong cycle life with a capacity retention of 93% after 10 000 cycles at 40 A g -1 . More importantly, when coupled with LiFePO 4 cathode, the fabricated lithium-ion full cells also exhibit high capacity and excellent rate and cycling performances, highlighting the practicability of this NC@GF. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Epataxial growth of the high-temperature superconductors YBa2Cu3O7-x on silicon single crystals with buffer layers

    International Nuclear Information System (INIS)

    Lubig, A.

    1991-09-01

    In this work the growth of thin films of the high-temperature superconductor YBa 2 Cu 3 O 7-x on Si(001) substrates has been investigated by Rutherford backscattering, channeling, X-ray diffraction, high resolution transmission electron microscopy, and electrical measurements. Epitaxial buffer layers of electrically insulating, pure and yttria-stabilized ZrO 2 ([Y 2 O 3 ] 0.06 [ZrO 2 ] 0.94 = YSZ) as well as of metallic CoSi 2 were employed to largely prevent the interdiffusion and chemical reaction between the superconductor film and the substrate in spite of the high deposition temperatures of the YBa 2 Cu 3 O 7-x in the range of 600 to 800deg C. (orig.)

  12. Effects of the Buffer Layers on the Adhesion and Antimicrobial Properties of the Amorphous ZrAlNiCuSi Films

    Science.gov (United States)

    Chiang, Pai-Tsung; Chen, Guo-Ju; Jian, Sheng-Rui; Shih, Yung-Hui

    2011-06-01

    To extend the practical applications of the bulk metallic glasses (BMGs), the preparation of the metallic glass coatings on various substrates becomes an important research issue. Among the interfacial properties of the coatings, the adhesion between films and substrates is the most crucial. In this study, amorphous Zr61Al7.5Ni10Cu17.5Si4 (ZrAlNiCuSi) thin films were deposited on SUS304 stainless steel at various sputtering powers by DC sputtering. According to the scratch tests, the introduction of the Cr and Ti buffer layers effectively improves the adhesion between the amorphous thin films and substrate without changing the surface properties, such as roughness and morphology. The antimicrobial results show that the biological activities of these microbes, except Acinetobacter baumannii, are effectively suppressed during the test period.

  13. Self-assembly surface modified indium-tin oxide anodes for single-layer light-emitting diodes

    CERN Document Server

    Morgado, J; Charas, A; Matos, M; Alcacer, L; Cacialli, F

    2003-01-01

    We study the effect of indium-tin oxide surface modification by self assembling of highly polar molecules on the performance of single-layer light-emitting diodes (LEDs) fabricated with polyfluorene blends and aluminium cathodes. We find that the efficiency and light-output of such LEDs is comparable to, and sometimes better than, the values obtained for LEDs incorporating a hole injection layer of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid. This effect is attributed to the dipole-induced work function modification of indium-tin oxide.

  14. Self-assembly surface modified indium-tin oxide anodes for single-layer light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Jorge [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Barbagallo, Nunzio [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Charas, Ana [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Matos, Manuel [Departamento de Engenharia Quimica, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro-1, P-1949-001 Lisbon (Portugal); Alcacer, Luis [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Cacialli, Franco [Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT (United Kingdom)

    2003-03-07

    We study the effect of indium-tin oxide surface modification by self assembling of highly polar molecules on the performance of single-layer light-emitting diodes (LEDs) fabricated with polyfluorene blends and aluminium cathodes. We find that the efficiency and light-output of such LEDs is comparable to, and sometimes better than, the values obtained for LEDs incorporating a hole injection layer of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid. This effect is attributed to the dipole-induced work function modification of indium-tin oxide.

  15. Effect of processing conditions and methods on residual stress in CeO2 buffer layers and YBCO superconducting films

    International Nuclear Information System (INIS)

    Xiong Jie; Qin Wenfeng; Cui Xumei; Tao Bowan; Tang Jinlong; Li Yanrong

    2006-01-01

    CeO 2 layers have been fabricated by pulsed laser deposition (PLD) technique on (1 1 0 2) sapphire substrate. Microstructure of CeO 2 layers is characterized by X-ray diffraction as functions of substrate temperature. The effects of the substrate temperature on the residual stress have been studied. The results show that residual stress in CeO 2 film decreased with increasing substrate temperature, not the same development tendency as that of thermal stress. This means that the thermal stress is only a fraction of the residual stress. Moreover, YBCO superconducting films were prepared by direct current (DC) sputtering and pulsed laser deposition (PLD) technique. The residual stress and thermal stress of both YBCO films were measured. PLD processing apparently generated higher intrinsic compressive stresses in comparison to DC sputtering

  16. Effects of BaBi2Ta2O9 thin buffer layer on crystallization and electrical properties of CaBi2Ta2O9 thin films on Pt-coated silicon

    Science.gov (United States)

    Kato, Kazumi; Suzuki, Kazuyuki; Nishizawa, Kaori; Miki, Takeshi

    2001-05-01

    Non-c-axis oriented CaBi2Ta2O9 (CBT) thin films have been successfully deposited via the triple alkoxide solution method on Pt-coated Si substrates by inserting BaBi2Ta2O9 (BBT) thin buffer layers. The BBT thin buffer layer, which was prepared on Pt-coated Si, was a key material for suppression of the nonpolar c-axis orientation and promoting the ferroelectric structure perpendicular to the in-plane direction of CBT thin film. The annealing temperature and thickness of the BBT thin buffer layers affected the dielectric, ferroelectric, and fatigue properties of the stacked CBT/BBT thin films. The resultant 650 °C annealed CBT/BBT(30 nm) thin film exhibited good P-E hysteresis properties and fatigue behaviors.

  17. Use of different Zn precursors for the deposition of Zn(S,O) buffer layers by chemical bath for chalcopyrite based Cd-free thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Saez-Araoz, R.; Lux-Steiner, M.C. [Hahn Meitner Institut, Berlin (Germany); Freie Universitaet Berlin, Berlin (Germany); Ennaoui, A.; Kropp, T.; Veryaeva, E. [Hahn Meitner Institut, Berlin (Germany); Niesen, T.P. [AVANCIS GmbH and Co. KG, Munich (Germany)

    2008-10-15

    Progress in fabricating Cu(In,Ga)(S,Se){sub 2} (CIGSSe) solar cells with Zn(S,O) buffer layers prepared by chemical bath deposition (CBD) is discussed. The effect of different Zn salt precursors on solar cell device performance is investigated using production scale CIGSSe absorbers provided by AVANCIS GmbH and Co. KG. The CBD process has been developed at the Hahn-Meitner-Institut (HMI) using zinc nitrate, zinc sulphate or zinc chloride as zinc precursor. An average efficiency of 14.2{+-}0.8% is obtained by using one-layer CBD Zn(S,O) The dominant recombination path for well performing solar cells is discussed based on the results obtained from temperature dependent J(V) analysis. The structure and morphology of buffer layers deposited using zinc nitrate and zinc sulphate has been studied by means of transmission electron micrographs of glass/Mo/CIGSSe/Zn(S,O) structures. Results show a conformal coverage of the absorber by a Zn(S,O) layer of 15-25 nm consisting of nanocrystals with radii of {proportional_to}5 nm. XAES analysis of the buffer layer reveals a similar surface composition for buffer layers deposited with zinc nitrate and zinc sulphate. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. LaNiO(3) Buffer Layers for High Critical Current Density YBa(2)Cu(3)O(7-delta) and Tl(2)Ba(2)CaCu(2)O(8-delta) Films

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-08-24

    We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications.

  19. Effect of the laser sputtering parameters on the orientation of a cerium oxide buffer layer on sapphire and the properties of a YBa2Cu3Ox superconducting film

    DEFF Research Database (Denmark)

    Mozhaev, P. B.; Ovsyannikov, G. A.; Skov, Johannes

    1999-01-01

    The effect of the laser sputtering parameters on the crystal properties of CeO2 buffer layers grown on a (1 (1) under bar 02) sapphire substrate and on the properties of superconducting YBa2Cu3Ox thin films are investigated. It is shown that (100) and (111) CeO2 growth is observed, depending on t...... on the sputtering conditions. A buffer layer with the desired unidirectional orientation can be obtained by varying the heater temperature, the pressure in the chamber, and the energy density of the laser beam at the target. (C) 1999 American Institute of Physics....

  20. Interdiffusion studies on high-Tc superconducting YBa2Cu3O7-δ thin films on Si(111) with a NiSi2/ZrO2 buffer layer

    DEFF Research Database (Denmark)

    Aarnink, W.A.M.; Blank, D.H.A.; Adelerhof, D.J.

    1991-01-01

    Interdiffusion studies on high-T(c) superconducting YBa2Cu3O7-delta thin films with thickness in the range of 2000-3000 angstrom, on a Si(111) substrate with a buffer layer have been performed. The buffer layer consists of a 400 angstrom thick epitaxial NiSi2 layer covered with 1200 angstrom of p...

  1. Anodic oxidation

    CERN Document Server

    Ross, Sidney D; Rudd, Eric J; Blomquist, Alfred T; Wasserman, Harry H

    2013-01-01

    Anodic Oxidation covers the application of the concept, principles, and methods of electrochemistry to organic reactions. This book is composed of two parts encompassing 12 chapters that consider the mechanism of anodic oxidation. Part I surveys the theory and methods of electrochemistry as applied to organic reactions. These parts also present the mathematical equations to describe the kinetics of electrode reactions using both polarographic and steady-state conditions. Part II examines the anodic oxidation of organic substrates by the functional group initially attacked. This part particular

  2. Direct sub-nanometer scale electron microscopy analysis of anion incorporation to self-ordered anodic alumina layers

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Rovira, L.; Lopez-Haro, M.; Hungria, A.B.; El Amrani, K. [Department of Materials Science and Metallurgical Engineering and Inorganic Chemistry, University of Cadiz, Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Sanchez-Amaya, J.M. [Titania, Ensayos y Proyectos Industriales, S.L. Parque Tecnobahia, Edificio RETSE, Nave 4, 11500 El Puerto de Santa Maria (Cadiz) (Spain); Calvino, J.J. [Department of Materials Science and Metallurgical Engineering and Inorganic Chemistry, University of Cadiz, Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain); Botana, F.J., E-mail: javier.botana@uca.e [Department of Materials Science and Metallurgical Engineering and Inorganic Chemistry, University of Cadiz, Republica Saharaui s/n, 11510 Puerto Real, Cadiz (Spain)

    2010-11-15

    Research highlights: {yields} Morphological and chemical characterization at atomic scale of porous alumina layers anodised in ordered regimes. {yields} Characterization based on the use of FEG-SEM, STEM-HAADF, STEM-EELS and STEM-X-EDS. {yields} Nanoscale distribution of P-, C- and S-bearing species in the pore wall. - Abstract: Ordered porous alumina layers prepared by two-step anodising in phosphoric, oxalic and sulphuric acids have been characterized at sub-nanometer scale using electron microscopy techniques. FEG-SEM and STEM-HAADF images allowed estimating the pore size, cell wall and pore wall thicknesses of the layers. Nanoanalytical characterization has been performed by STEM-EELS and STEM-X-EDS. Detailed features of the spatial distribution of anions in the pore wall of the films have been obtained. Maximum concentration of P-species occurs, approximately, at the middle of the pore wall; adjacent to the pore for C-species, whereas the distribution of S-species appears to be uniform.

  3. Layer-by-layer assembled multilayers of polyethylenimine-stabilized platinum nanoparticles and PEDOT:PSS as anodes for the methanol oxidation reaction.

    Science.gov (United States)

    Knowles, Kyler R; Hanson, Colin C; Fogel, April L; Warhol, Brian; Rider, David A

    2012-07-25

    Polyethylenimine-capped platinum nanoparticles (PEI-capped Pt NPs) are synthesized by photoreduction and qualified as a component for electrostatic layer-by-layer assembly and subsequent electrocatalysis. The PEI-capped Pt NPs are characterized for size and charge using scanning force microscopy, transmission electron microscopy, dynamic light scattering and zetapotential. Well-defined multilayers are produced via thin film electrostatic assembly of PEI-capped Pt NPs with the conducting polymer: poly(3,4-ethylenedioxythiophene):poly(p-styrenesulfonate) [(PEDOT:PSS)(-)Na(+)]. The composite thin films are subsequently characterized by ultraviolet-visible spectroscopy, scanning force microscopy, inductively coupled plasma mass spectroscopy and thermogravimetric analysis. The layer-by-layer deposition process was found to proceed in a controlled manner which permits the fabrication of stable and uniform multilayer thin films. [PEI-capped Pt NPs/(PEDOT:PSS)] multilayers were found to be an active catalyst coating for the oxidation of methanol and a 20 bilayer film proceeds with a stable level of catalyst activity for over 1000 oxidation cycles.

  4. The Effect of Sintering Oxygen Partial Pressure on a SmBiO3 Buffer Layer for Coated Conductors via Chemical Solution Deposition

    Directory of Open Access Journals (Sweden)

    Xiaolei Zhu

    2016-10-01

    Full Text Available The application of high-temperature YBa2Cu3O7−δ (YBCO superconducting material is a considerable prospect for the growing energy shortages. Here, SmBiO3 (SBO films were deposited on (100-orientated yttrium-stabilized zirconia (YSZ simple crystal substrates via the chemical solution deposition (CSD approach for coated conductors, and the effects of sintering oxygen partial pressure on SBO films were studied. The crystalline structures and surface morphologies of SBO films were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and atomic force microscope (AFM. The optimized growth temperature, the intensity ratios of the SBO (200 peak to the SBO (111 peak, and the crystallinities of SBO films increased with the sintering oxygen partial pressure. The SEM and AFM images displayed a smooth and well-distributed surface in the argon atmosphere. The subsequent YBCO films with superconducting transition temperatures (Tc = 89.5 K, 90.2 K, and 86.2 K and critical current densities (Jc = 0.88 MA/cm2, 1.69 MA/cm2, and 0.09 MA/cm2; 77 K, self-field were deposited to further check the qualities of the SBO layer. These results indicated that sintering oxygen partial pressure had an effect on the epitaxial growth of the SBO buffer layer and YBCO superconducting properties. The experimental results may be a usable reference for the epitaxial growth of YBCO-coated conductors and other oxides.

  5. CdS and Cd-Free Buffer Layers on Solution Phase Grown Cu2ZnSn(SxSe1- x)4 :Band Alignments and Electronic Structure Determined with Femtosecond Ultraviolet Photoemission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Haight, Richard; Barkhouse, Aaron; Wang, Wei; Yu, Luo; Shao, Xiaoyan; Mitzi, David; Hiroi, Homare; Sugimoto, Hiroki

    2013-12-02

    The heterojunctions formed between solution phase grown Cu2ZnSn(SxSe1- x)4(CZTS,Se) and a number of important buffer materials including CdS, ZnS, ZnO, and In2S3, were studied using femtosecond ultraviolet photoemission spectroscopy (fs-UPS) and photovoltage spectroscopy. With this approach we extract the magnitude and direction of the CZTS,Se band bending, locate the Fermi level within the band gaps of absorber and buffer and measure the absorber/buffer band offsets under flatband conditions. We will also discuss two-color pump/probe experiments in which the band bending in the buffer layer can be independently determined. Finally, studies of the bare CZTS,Se surface will be discussed including our observation of mid-gap Fermi level pinning and its relation to Voc limitations and bulk defects.

  6. Efficient PEDOT:PSS-Free Polymer Solar Cells with an Easily Accessible Polyacrylonitrile Polymer Material as a Novel Solution-Processable Anode Interfacial Layer.

    Science.gov (United States)

    Noh, Yong-Jin; Park, Sae-Mi; Yeo, Jun-Seok; Kim, Dong-Yu; Kim, Seok-Soon; Na, Seok-In

    2015-11-18

    We demonstrate that an easily accessible polyacrylonitrile (PAN) polymer can efficiently function as a novel solution-processable anode interfacial layer (AIL) to boost the device performances of polymer:fullerene-based solar cells (PSCs). The PAN thin film was simply prepared with spin-coating of a cost-efficient PAN solution dissolved in dimethylformamide on indium tin oxide (ITO), and the thin polymeric interlayer on PSC parameters and stability were systemically investigated. As a result, the cell efficiency of the PSC with PAN was remarkably enhanced compared to the device using bare ITO. Furthermore, with PAN, we finally achieved an excellent power conversion efficiency (PCE) of 6.7% and a very high PSC stability in PTB7:PC71BM systems, which constitute a highly comparable PCE and superior device lifetime relative to those of conventional PSCs with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS). These results demonstrate that the inexpensive solution-processed PAN polymer can be an attractive PSS alternative and is more powerful for achieving better cell performances and lower cost PSC production.

  7. A novel radial anode layer ion source for inner wall pipe coating and materials modification--hydrogenated diamond-like carbon coatings from butane gas.

    Science.gov (United States)

    Murmu, Peter P; Markwitz, Andreas; Suschke, Konrad; Futter, John

    2014-08-01

    We report a new ion source development for inner wall pipe coating and materials modification. The ion source deposits coatings simultaneously in a 360° radial geometry and can be used to coat inner walls of pipelines by simply moving the ion source in the pipe. Rotating parts are not required, making the source ideal for rough environments and minimizing maintenance and replacements of parts. First results are reported for diamond-like carbon (DLC) coatings on Si and stainless steel substrates deposited using a novel 360° ion source design. The ion source operates with permanent magnets and uses a single power supply for the anode voltage and ion acceleration up to 10 kV. Butane (C4H10) gas is used to coat the inner wall of pipes with smooth and homogeneous DLC coatings with thicknesses up to 5 μm in a short time using a deposition rate of 70 ± 10 nm min(-1). Rutherford backscattering spectrometry results showed that DLC coatings contain hydrogen up to 30 ± 3% indicating deposition of hydrogenated DLC (a-C:H) coatings. Coatings with good adhesion are achieved when using a multiple energy implantation regime. Raman spectroscopy results suggest slightly larger disordered DLC layers when using low ion energy, indicating higher sp(3) bonds in DLC coatings. The results show that commercially interesting coatings can be achieved in short time.

  8. Carbon-coated ZnO mat passivation by atomic-layer-deposited HfO2as an anode material for lithium-ion batteries.

    Science.gov (United States)

    Jung, Mi-Hee

    2017-11-01

    ZnO has had little consideration as an anode material in lithium-ion batteries compared with other transition-metal oxides due to its inherent poor electrical conductivity and large volume expansion upon cycling and pulverization of ZnO-based electrodes. A logical design and facile synthesis of ZnO with well-controlled particle sizes and a specific morphology is essential to improving the performance of ZnO in lithium-ion batteries. In this paper, a simple approach is reported that uses a cation surfactant and a chelating agent to synthesize three-dimensional hierarchical nanostructured carbon-coated ZnO mats, in which the ZnO mats are composed of stacked individual ZnO nanowires and form well-defined nanoporous structures with high surface areas. In order to improve the performance of lithium-ion batteries, HfO 2 is deposited on the carbon-coated ZnO mat electrode via atomic layer deposition. Lithium-ion battery devices based on the carbon-coated ZnO mat passivation by atomic layer deposited HfO 2 exhibit an excellent initial discharge and charge capacities of 2684.01 and 963.21mAhg -1 , respectively, at a current density of 100mAg -1 in the voltage range of 0.01-3V. They also exhibit cycle stability after 125 cycles with a capacity of 740mAhg -1 and a remarkable rate capability. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Dithienylpyrrole- and Tris[4-(2-thienylphenyl]amine-Containing Copolymers as Promising Anodic Layers in High-Contrast Electrochromic Devices

    Directory of Open Access Journals (Sweden)

    Tzi-Yi Wu

    2018-04-01

    Full Text Available Three dithienylpyrrole- and tris[4-(2-thienylphenyl]amine-containing copolymers (P(MPS-co-TTPA, P(MPO-co-TTPA, and P(ANIL-co-TTPA were deposited on indium tin oxide (ITO surfaces using electrochemical polymerization. Spectroelectrochemical characterizations of polymer films revealed that P(MPS-co-TTPA film was light olive green, greyish-green, bluish grey, and grey in neutral state, intermediate state, oxidized state, and highly oxidized state, respectively, whereas P(MPO-co-TTPA film was green moss, foliage green, dark greyish-green, and bluish-grey in neutral state, intermediate state, oxidized state, and highly oxidized state, respectively. The ΔTmax of P(MPS-co-TTPA film at 964 nm, P(MPO-co-TTPA film at 914 nm, and P(ANIL-co-TTPA film at 960 nm were 67.2%, 60.7%, and 67.1%, respectively, and the coloration efficiency (η of P(MPS-co-TTPA film at 964 nm, P(MPO-co-TTPA film at 914 nm, and P(ANIL-co-TTPA film at 960 nm were calculated to be 260.3, 176.6, and 230.8 cm2 C−1, respectively. Dual type complementary colored electrochromic devices (ECDs were constructed using P(MPS-co-TTPA, P(MPO-co-TTPA, or P(ANIL-co-TTPA as anodic copolymer layer and PProDOT-Et2 as cathodic polymer layer. P(MPO-co-TTPA/PProDOT-Et2 ECD revealed high ΔT (55.1% and high η (766.5 cm2 C−1 at 580 nm. Moreover, P(MPS-co-TTPA/PProDOT-Et2, P(MPO-co-TTPA/PProDOT-Et2, and P(ANIL-co-TTPA/PProDOT-Et2 ECDs showed satisfactory long-term cycling stability and optical memory.

  10. Gas phase condensation of few-layer graphene with rotational stacking faults in an electric-arc

    OpenAIRE

    Karmakar, Soumen; Nawale, Ashok B.; Lalla, Niranjan P.; Sathe, Vasant G.; Mathe, Vikas L.; Das, Asoka K.; Bhoraskar, Sudha V.

    2012-01-01

    We report the synthesis efficiency of few-layer graphene (FLG) in an external magnetic field modulated DC carbon arc in different non-reactive buffer gases. The effects of buffer gases on the anode erosion rate and the cathode deposit (CD) formation rate have been investigated during the synthesis of FLG. The constituents of the as-synthesized CDs were investigated using transmission electron microscopy, selected area electron diffraction, Raman spectroscopy and X-ray diffraction analysis. A ...

  11. Spray-Pyrolyzed Three-Dimensional CuInS2 Solar Cells on Nanocrystalline-Titania Electrodes with Chemical-Bath-Deposited Inx(OH)ySz Buffer Layers

    Science.gov (United States)

    Nguyen, Duy-Cuong; Mikami, Yuki; Tsujimoto, Kazuki; Ryo, Toshihiro; Ito, Seigo

    2012-10-01

    Three-dimensional (3D) compound solar cells with the structure of plates> have been fabricated by spray pyrolysis deposition of CuInS2 and chemical-bath deposition of Inx(OH)ySz for the light absorber and buffer layer, respectively. The effect of deposition and annealing conditions of Inx(OH)ySz on the photovoltaic properties of 3D CuInS2 solar cells was investigated. Inx(OH)ySz annealed in air ambient showed a better cell performance than those annealed in nitrogen ambient and without annealing. The improvement of the performance of cells with Inx(OH)ySz buffer layers annealed in air ambient is due to the increase in oxide concentration in the buffer layers [confirmed by X-ray photoelectron spectroscopy (XPS) measurement]. Among cells with Inx(OH)ySz buffer layers deposited for 1, 1.5, 1.75, and 2 h, that with Inx(OH)ySz deposited for 1.75 h showed the best cell performance. The best cell performance was observed for Inx(OH)ySz deposited for 1.75 h with annealing at 300 °C for 30 min in air ambient, and cell parameters were 22 mA cm-2 short-circuit photocurrent density, 0.41 V open-circuit voltage, 0.35 fill factor, and 3.2% conversion efficiency.

  12. Characterization of La0.995Ca0.005NbO4/Ni anode functional layer by electrophoretic deposition in a La0.995Ca0.005NbO4 electrolyte based PCFC

    DEFF Research Database (Denmark)

    Bozza, Francesco; Schafbauer, W.; Meulenberg, W.A.

    2012-01-01

    The Electrophoretic Deposition (EPD) technique has been applied to the preparation of a porous La0.995Ca0.005NbO4/Ni composite anode layer, deposited on a porous pre-sintered La0.995Ca0.005NbO4/Ni support. Powders of La0.995Ca0.005NbO4 and NiO were suspended in a solution of acetylacetone, iodine...

  13. Full cell simulation and the evaluation of the buffer system on air-cathode microbial fuel cell

    Science.gov (United States)

    Ou, Shiqi; Kashima, Hiroyuki; Aaron, Douglas S.; Regan, John M.; Mench, Matthew M.

    2017-04-01

    This paper presents a computational model of a single chamber, air-cathode MFC. The model considers losses due to mass transport, as well as biological and electrochemical reactions, in both the anode and cathode half-cells. Computational fluid dynamics and Monod-Nernst analysis are incorporated into the reactions for the anode biofilm and cathode Pt catalyst and biofilm. The integrated model provides a macro-perspective of the interrelation between the anode and cathode during power production, while incorporating microscale contributions of mass transport within the anode and cathode layers. Model considerations include the effects of pH (H+/OH- transport) and electric field-driven migration on concentration overpotential, effects of various buffers and various amounts of buffer on the pH in the whole reactor, and overall impacts on the power output of the MFC. The simulation results fit the experimental polarization and power density curves well. Further, this model provides insight regarding mass transport at varying current density regimes and quantitative delineation of overpotentials at the anode and cathode. Overall, this comprehensive simulation is designed to accurately predict MFC performance based on fundamental fluid and kinetic relations and guide optimization of the MFC system.

  14. Effect of surface modification of CeO2 buffer layers on Jc and defect microstructures of large-area YBCO thin films

    International Nuclear Information System (INIS)

    Develos-Bagarinao, K; Yamasaki, H; Nakagawa, Y

    2006-01-01

    High-quality CeO 2 buffer layers are requisite for the successful growth of YBCO thin films with excellent properties on sapphire substrates. In this study, we evaluated the effect of surface modification of the CeO 2 layers on the properties of the YBCO thin films prepared by large-area pulsed laser deposition (PLD), in particular the critical current density J c and defect microstructure. High-temperature annealing (1050 deg. C ) has been found to significantly smoothen the very rough and granular surfaces of the as-grown CeO 2 layers (surface roughness rms∼5-10 nm) to atomic flatness (rms∼0.5 nm). However, a rather unique characteristic of the CeO 2 layers deposited by large-area PLD is the development of pores when subjected to prolonged high-temperature annealing. For very short annealing periods (10-20 min), the surface morphology becomes atomically flat, along with the appearance of a high density of 'nanopores' that are ∼40-100 nm in diameter and ∼3-5 nm in depth. Extending the annealing period to 60 min or more results in the development of a surface subtended with enlarged pores ∼0.2-0.5 μm in diameter. Compared with the YBCO thin films deposited on as-grown CeO 2 , YBCO thin films on annealed CeO 2 exhibited better homogeneity of J c and better crystalline texture. Among the YBCO thin films deposited on annealed CeO 2 , higher self-field and in-field J c was obtained for YBCO thin films deposited on CeO 2 with smooth surfaces but interspersed with nanopores. Investigation of the defect microstructure via the etch pit method in conjunction with atomic force microscopy (AFM) of the YBCO thin films revealed a high density of linear defects in the form of screw and edge dislocations, which correlated well with a high density of nanopores on annealed CeO 2 . Transmission electron microscopy (TEM) further confirmed the presence of threading dislocations clearly emanating from the nanopore sites. Angular dependence of J c revealed enhanced flux

  15. Threading dislocation reduction in three-dimensionally grown GaN islands on Si (111) substrate with AlN/AlGaN buffer layers

    Science.gov (United States)

    Chang, Shane; Lung Wei, Lin; Tung Luong, Tien; Chang, Ching; Chang, Li

    2017-09-01

    Three-dimensional GaN island growth without any masks was first introduced under high pressure in metalorganic chemical vapor deposition after the growth of AlN and AlGaN buffer layers on Si (111) substrate, followed by two-dimensional GaN growth to form a continuous GaN film with improvement of the crystalline quality and surface smoothness. X-ray diffraction and cross-sectional scanning transmission electron microscopy analyses show that a high-quality GaN film can be achieved by bending of edge threading dislocations (TDs) and the formation of dislocation half-loops. It is observed that most of edge TDs bend 90° from the growth direction along c-axis, whereas mixed TDs bend about 30° towards the inclined sidewall facets of the islands. Consequently, a 1.2 μm thick GaN epitaxial film with a low threading dislocation density of 2.5 × 108 cm-2 and a smooth surface of 0. 38 nm roughness can be achieved on Si substrate.

  16. Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

    Science.gov (United States)

    Tham, Kim Kong; Kushibiki, Ryosuke; Kamada, Tomonari; Hinata, Shintaro; Saito, Shin

    2018-05-01

    Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms), uniaxial magnetocrystalline anisotropy (Ku), and magnetic grain diameter (GD) of the granular media show linear correlation with volume weighted average for melting point (Tm) of each oxides (Tmave). Ku of magnetic grains (Kugrain) shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α). By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

  17. Anode Fall Formation in a Hall Thruster

    International Nuclear Information System (INIS)

    Dorf, Leonid A.; Raitses, Yevgeny F.; Smirnov, Artem N.; Fisch, Nathaniel J.

    2004-01-01

    As was reported in our previous work, accurate, nondisturbing near-anode measurements of the plasma density, electron temperature, and plasma potential performed with biased and emissive probes allowed the first experimental identification of both electron-repelling (negative anode fall) and electron-attracting (positive anode fall) anode sheaths in Hall thrusters. An interesting new phenomenon revealed by the probe measurements is that the anode fall changes from positive to negative upon removal of the dielectric coating, which appears on the anode surface during the course of Hall thruster operation. As reported in the present work, energy dispersion spectroscopy analysis of the chemical composition of the anode dielectric coating indicates that the coating layer consists essentially of an oxide of the anode material (stainless steel). However, it is still unclear how oxygen gets into the thruster channel. Most importantly, possible mechanisms of anode fall formation in a Hall thruster with a clean and a coated anodes are analyzed in this work; practical implication of understanding the general structure of the electron-attracting anode sheath in the case of a coated anode is also discussed

  18. Influence of the buffer-layer on the tunnel barrier quality in CoFeB/MgO/CoFeB magnetic tunnel junctions on the tunnel magneto resistance (TMR)

    Energy Technology Data Exchange (ETDEWEB)

    Zbarsky, Vladyslav; Walter, Marvin; Eilers, Gerrit; Leutenantsmeyer, Johannes Christian; Muenzenberg, Markus [I. Physikalisches Institut, Georg-August-Universitaet Goettingen, 37077 Goettingen (Germany); Peretzki, Patrick; Seibt, Michael [IV. Physikalisches Institut, Georg-August-Universitaet Goettingen, 37077 Goettingen (Germany)

    2011-07-01

    The optimization of MTJs is necessary for increasing of TMR and therefore is very important for the production of MRAM devices. The quality of the tunnel barrier of our CoFeB/MgO/CoFeB MTJs is essential for getting high TMR. For this reason we investigate the influence of roughness of the MgO layer on the TMR. Another important parameter which we could optimize is the choice and preparation of the buffer-layer. For example we compared two sorts of Ta buffer-layers: prepared via magnetron sputtering and via e-beam evaporation. Already by optimizing these two parameters we increase the TMR from 80% to above 200%. In addition we show the investigations of the influence of the annealing temperatures and annealing duration on the TMR. Fast annealing time prevents diffusion, however for short annealing time no full crystallization is observed.

  19. Buffer-layer enhanced crystal growth of BaB{sub 6} (1 0 0) thin films on MgO (1 0 0) substrates by laser molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Yushi; Yamauchi, Ryosuke; Arai, Hideki; Tan, Geng [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259-J2-46, Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Tsuchimine, Nobuo; Kobayashi, Susumu [Toshima Manufacturing Company Limited, 1414 Shimonomoto, Higashimatsuyama-shi, Saitama 355-0036 (Japan); Saeki, Kazuhiko; Takezawa, Nobutaka [Department of Materials Technology, Industrial Technology Center of Tochigi Prefecture, 367-1 Karinuma, Utsunomiya-shi, Tochigi 321-3224 (Japan); Mitsuhashi, Masahiko; Kaneko, Satoru [Kanagawa Industrial Technology Center, Kanagawa Prefectural Government, 705-1 Shimo-Imaizumi, Ebina, Kanagawa 243-0435 (Japan); Yoshimoto, Mamoru, E-mail: yoshimoto.m.aa@m.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259-J2-46, Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan); Patent Attorney, Tokyo Institute of Technology, 4259-J2-46, Nagatsuta-cho, Midori-ku, Yokohama 226-8503 (Japan)

    2012-02-01

    Crystalline BaB{sub 6} (1 0 0) thin films can be fabricated on MgO (1 0 0) substrates by inserting a 2-3 nm-thick epitaxial SrB{sub 6} (1 0 0) buffer layer by pulsed laser deposition (PLD) in ultra-high vacuum (i.e., laser molecular beam epitaxy). Reflection high-energy electron diffraction and X-ray diffraction measurements indicated the heteroepitaxial structure of BaB{sub 6} (1 0 0)/SrB{sub 6} (1 0 0)/MgO (1 0 0) with the single domain of the epitaxial relationship. Conversely, BaB{sub 6} thin films without the buffer layer were not epitaxial instead they developed as polycrystalline films with a random in-plane configuration and some impurity phases. As a result, the buffer layer is considered to greatly affect the initial growth of epitaxial BaB{sub 6} thin films; therefore, in this study, buffering effects have been discussed. From the conventional four-probe measurement, it was observed that BaB{sub 6} epitaxial thin films exhibit n-type semiconducting behavior with a resistivity of 2.90 Multiplication-Sign 10{sup -1} {Omega} cm at room temperature.

  20. Suppression on allotropic transformation of Sn planar anode with enhanced electrochemical performance

    Science.gov (United States)

    Wang, Peng; Hu, Junhua; Cao, Guoqin; Zhang, Shilin; Zhang, Peng; Liang, Changhao; Wang, Zhuo; Shao, Guosheng

    2018-03-01

    Different configurations of Sn and C films were deposited and used as a planar anode for Li ion battery. The interplay of carbon layer with Sn as supporting and buffering, respectively, was revealed. The suppression on the allotropic transformation to α phase by a carbon layer results in a significantly improved capacity retention rate, which also avoids the crack of Sn film. As expected, a conductive carbon layer improves rating performance. However, a supporting carbon layer (SC) just contributes to the charge transfer process. A DFT approach was used to assess the allotropic transformation process. An additional barrier (∼0.86 eV) exits on the α-β diagram, which is responsible for the irreversibility of α phase back to β phase. An enhanced persistence of β phase in Sn/C anode contributes to cycling performance. A Li rich condition contributes to the stabilization of β-Sn, which is thermodynamically favored. A nano buffering carbon (BC) layer can evidently alleviate the side reaction on Sn surface, which in turn promotes the diffusion of Li ions in electrode and generates a Li rich condition. The direct contact of Sn with electrolyte leads to serious accumulation of α-Sn during cycling and results in a poor cycling performance. By the synergistic effect of BC and SC, a sandwich C/Sn/C structure demonstrates an enchantment in electrochemical behavior.

  1. Buffer layers for coated conductors

    Science.gov (United States)

    Stan, Liliana [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM; Foltyn, Stephen R [Los Alamos, NM

    2011-08-23

    A composite structure is provided including a base substrate, an IBAD oriented material upon the base substrate, and a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the IBAD oriented material. Additionally, an article is provided including a base substrate, an IBAD oriented material upon the base substrate, a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the IBAD oriented material, and a thick film upon the cubic metal oxide material. Finally, a superconducting article is provided including a base substrate, an IBAD oriented material upon the base substrate, a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the IBAD oriented material, and an yttrium barium copper oxide material upon the cubic metal oxide material.

  2. Barrier efficiency of sponge-like La{sub 2}Zr{sub 2}O{sub 7} buffer layers for YBCO-coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Molina, Leopoldo; Tan, Haiyan; Biermans, Ellen; Verbeeck, Jo; Bals, Sara; Tendeloo, Gustaaf Van [EMAT, University of Antwerp, Groenenborgerlaan 171, BE-2020 Antwerp (Belgium); Batenburg, Kees J, E-mail: leopoldo.molina-luna@ua.ac.be [Vision Lab, University of Antwerp, Universiteitsplein 1, BE-2020 Wilrijk (Belgium)

    2011-06-15

    Solution derived La{sub 2}Zr{sub 2}O{sub 7} films have drawn much attention for potential applications as thermal barriers or low-cost buffer layers for coated conductor technology. Annealing and coating parameters strongly affect the microstructure of La{sub 2}Zr{sub 2}O{sub 7}, but different film processing methods can yield similar microstructural features such as nanovoids and nanometer-sized La{sub 2}Zr{sub 2}O{sub 7} grains. Nanoporosity is a typical feature found in such films and the implications for the functionality of the films are investigated by a combination of scanning transmission electron microscopy (STEM), electron energy-loss spectroscopy (EELS) and quantitative electron tomography. Chemical solution based La{sub 2}Zr{sub 2}O{sub 7} films deposited on flexible Ni-5 at.%W substrates with a {l_brace}100{r_brace}(001) biaxial texture were prepared for an in-depth characterization. A sponge-like structure composed of nanometer-sized voids is revealed by high-angle annular dark-field scanning transmission electron microscopy in combination with electron tomography. A three-dimensional quantification of nanovoids in the La{sub 2}Zr{sub 2}O{sub 7} film is obtained on a local scale. Mostly non-interconnected highly faceted nanovoids compromise more than one-fifth of the investigated sample volume. The diffusion barrier efficiency of a 170 nm thick La{sub 2}Zr{sub 2}O{sub 7} film is investigated by STEM-EELS, yielding a 1.8 {+-} 0.2 nm oxide layer beyond which no significant nickel diffusion can be detected and intermixing is observed. This is of particular significance for the functionality of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} coated conductor architectures based on solution derived La{sub 2}Zr{sub 2}O{sub 7} films as diffusion barriers.

  3. 1,3,5-Tris(phenyl-2-benzimidazole)-benzene cathode buffer layer thickness dependence in solution-processable organic solar cell based on 1,4,8,11,15,18,22,25-octahexylphthalocyanine

    Science.gov (United States)

    De Roméo Banoukepa, Gilles; Fujii, Akihiko; Shimizu, Yo; Ozaki, Masanori

    2015-04-01

    Studies on the insertion effects of a cathode buffer layer on bulk heterojunction organic solar cell based on 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) and 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C61 (PCBM) by using 1,3,5-tris(phenyl-2-benzimidazole)-benzene (TPBi) as a cathode buffer layer material have been carried out. The external quantum efficiency and the short-circuit current markedly increased, resulting in the enhancement of the power conversion efficiency. The solar cell performance has been discussed from the atomic force microscopy, photoelectron yield spectroscopy and X-ray photoelectron spectroscopy measurements.

  4. Strain relief and AlSb buffer layer morphology in GaSb heteroepitaxial films grown on Si as revealed by high-angle annular dark-field scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Vajargah, S. Hosseini; Couillard, M.; Cui, K.; Tavakoli, S. Ghanad; Robinson, B.; Kleiman, R. N.; Preston, J. S.; Botton, G. A.

    2011-01-01

    The interfacial misfit (IMF) dislocation array of an epitaxial GaSb film on a Si substrate has been imaged with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The mismatch strain accommodation through dislocation formation has been investigated using geometric phase analysis (GPA) on HAADF-STEM images with atomic resolution to probe the defects' local strain distribution. These measurements indicate that the lattice parameter of the epitaxial film recovers its bulk value within three unit cells from the interface due to the relaxation through IMF dislocations. The atomic number contrast of the HAADF-STEM images and energy dispersive x-ray spectrometry illustrate the formation of islands of AlSb buffer layer along the interface. The role of the AlSb buffer layer in facilitating the GaSb film growth on Si is further elucidated by investigating the strain field of the islands with the GPA.

  5. Investigation of ionic movements during anodic oxidation of superimposed metallic layers by the use of Rutherford backscattering techniques and nuclear micro analysis

    International Nuclear Information System (INIS)

    Perriere, J.; Siejka, J.; Rigo, S.

    1980-01-01

    Nuclear micro-analysis by the direct observation of nuclear reactions and of backscattered particles was used to study ionic movements during the anodization of superimposed metallic films (M 1 -M 2 systems). It has been shown that the order of cations is largely preserved during the anodization of Ta-Nb or Al-Nb systems while it is inverted in the case of Nb-Ta and Nb-Al systems. These results are discussed in terms of differences in jump probabilities of atoms. The oxygen movements in these systems were studied by 18 O tracing techniques; the results suggest that a correlation exists between oxygen and cationic migration during anodic oxide growth. The discussion of these results in terms of microscopic transport mechanisms is based on a neighbour to neighbour type propagation process for cationic as well as oxygen movement. (author)

  6. Spatial atomic layer deposition on flexible porous substrates: ZnO on anodic aluminum oxide films and Al2O3 on Li ion battery electrodes

    International Nuclear Information System (INIS)

    Sharma, Kashish; Routkevitch, Dmitri; Varaksa, Natalia; George, Steven M.

    2016-01-01

    Spatial atomic layer deposition (S-ALD) was examined on flexible porous substrates utilizing a rotating cylinder reactor to perform the S-ALD. S-ALD was first explored on flexible polyethylene terephthalate polymer substrates to obtain S-ALD growth rates on flat surfaces. ZnO ALD with diethylzinc and ozone as the reactants at 50 °C was the model S-ALD system. ZnO S-ALD was then performed on nanoporous flexible anodic aluminum oxide (AAO) films. ZnO S-ALD in porous substrates depends on the pore diameter, pore aspect ratio, and reactant exposure time that define the gas transport. To evaluate these parameters, the Zn coverage profiles in the pores of the AAO films were measured using energy dispersive spectroscopy (EDS). EDS measurements were conducted for different reaction conditions and AAO pore geometries. Substrate speeds and reactant pulse durations were defined by rotating cylinder rates of 10, 100, and 200 revolutions per minute (RPM). AAO pore diameters of 10, 25, 50, and 100 nm were utilized with a pore length of 25 μm. Uniform Zn coverage profiles were obtained at 10 RPM and pore diameters of 100 nm. The Zn coverage was less uniform at higher RPM values and smaller pore diameters. These results indicate that S-ALD into porous substrates is feasible under certain reaction conditions. S-ALD was then performed on porous Li ion battery electrodes to test S-ALD on a technologically important porous substrate. Li 0.20 Mn 0.54 Ni 0.13 Co 0.13 O 2 electrodes on flexible metal foil were coated with Al 2 O 3 using 2–5 Al 2 O 3 ALD cycles. The Al 2 O 3 ALD was performed in the S-ALD reactor at a rotating cylinder rate of 10 RPM using trimethylaluminum and ozone as the reactants at 50 °C. The capacity of the electrodes was then tested versus number of charge–discharge cycles. These measurements revealed that the Al 2 O 3 S-ALD coating on the electrodes enhanced the capacity stability. This S-ALD process could be extended to roll-to-roll operation for

  7. Mapping cation diffusion through lattice defects in epitaxial oxide thin films on the water-soluble buffer layer Sr3Al2O6 using atomic resolution electron microscopy

    Science.gov (United States)

    Baek, David J.; Lu, Di; Hikita, Yasuyuki; Hwang, Harold Y.; Kourkoutis, Lena F.

    2017-09-01

    Recent advances in the synthesis of oxide thin films have led to the discovery of novel functionalities that are not accessible in bulk structures. However, their physical properties are vulnerable to the presence of crystal defects, which can give rise to structural, chemical, and electronic modifications. These issues are central to optimizing the opportunities to create freestanding oxide films using the recently developed buffer layer Sr3Al2O6, which is soluble in room temperature water. To evaluate the general possibility to create atomic scale freestanding oxide heterostructures, it is critical to understand the formation, structure, and role of defects as this buffer layer is employed. Here, using aberration-corrected scanning transmission electron microscopy in combination with electron energy loss spectroscopy, we reveal cation segregation and diffusion along crystal defects that form during growth of an oxide multilayer structure on the Sr3Al2O6 buffer layer. We demonstrate that mass transport of film material can occur either through open dislocation core channels or site-specifically in the crystal lattice, causing local variations in stoichiometry. However, by reducing the thermal driving force for diffusion during growth, we suppress the role of extended defects as cation segregation sites, thereby retaining the inherent properties of the overlaying film.

  8. Mapping cation diffusion through lattice defects in epitaxial oxide thin films on the water-soluble buffer layer Sr3Al2O6 using atomic resolution electron microscopy

    Directory of Open Access Journals (Sweden)

    David J. Baek

    2017-09-01

    Full Text Available Recent advances in the synthesis of oxide thin films have led to the discovery of novel functionalities that are not accessible in bulk structures. However, their physical properties are vulnerable to the presence of crystal defects, which can give rise to structural, chemical, and electronic modifications. These issues are central to optimizing the opportunities to create freestanding oxide films using the recently developed buffer layer Sr3Al2O6, which is soluble in room temperature water. To evaluate the general possibility to create atomic scale freestanding oxide heterostructures, it is critical to understand the formation, structure, and role of defects as this buffer layer is employed. Here, using aberration-corrected scanning transmission electron microscopy in combination with electron energy loss spectroscopy, we reveal cation segregation and diffusion along crystal defects that form during growth of an oxide multilayer structure on the Sr3Al2O6 buffer layer. We demonstrate that mass transport of film material can occur either through open dislocation core channels or site-specifically in the crystal lattice, causing local variations in stoichiometry. However, by reducing the thermal driving force for diffusion during growth, we suppress the role of extended defects as cation segregation sites, thereby retaining the inherent properties of the overlaying film.

  9. Buffers Plus

    Science.gov (United States)

    Ramette, Richard W.

    1998-11-01

    In 1989 JCE Software published The Acid-Base Package: A Collection of Useful Programs for Proton Transfer Systems (Ramette, R. W. J. Chem. Educ. Software 1989, 2B No. 2). This DOS program has been fully upgraded by the same author to the world of Windows 95. Buffers Plus takes advantage of a modern user interface and offers many new options not possible in the original version.

  10. The growth of a low defect InAs HEMT structure on Si by using an AlGaSb buffer layer containing InSb quantum dots for dislocation termination.

    Science.gov (United States)

    Ko, Kwang-Man; Seo, Jung-Han; Kim, Dong-Eun; Lee, Sang-Tae; Noh, Young-Kyun; Kim, Moon-Deock; Oh, Jae-Eung

    2009-06-03

    It is found that the surface migration and nucleation behaviors of InSb quantum dots on AlSb/Si substrates, formed by molecular beam epitaxy in Stranski-Krastanov (SK) growth mode, are dependent on the substrate temperature. At relatively high temperatures above 430 degrees C, quantum dots are migrated and preferentially assembled onto the surface steps of high defect AlSb layers grown on Si substrates, while they are uniformly distributed on the surface at lower temperatures below 400 degrees C. It is also found that quantum dots located on the defect sites lead to effective termination of the propagation of micro-twin-induced structural defects into overlying layers, resulting in the low defect material grown on a largely mismatched substrate. The resulting 1.0 microm thick Al(x)Ga(1-x)Sb (x = 0.8) layer grown on the silicon substrate shows atomically flat (0.2 nm AFM mean roughness) surface and high crystal quality, represented by a narrow full width at half-maximum of 300 arc s in the x-ray rocking curve. The room-temperature electron mobility of higher than 16 000 cm(2) V(-1) s(-1) in InAs/AlGaSb FETs on the Si substrate is obtained with a relatively thin buffer layer, when a low defect density ( approximately 10(6) cm(-2)) AlGaSb buffer layer is obtained by the proposed method.

  11. Self-organized anodic TiO.sub.2./sub. nanotube layers: influence of the Ti substrate on nanotube growth and dimensions

    Czech Academy of Sciences Publication Activity Database

    Sopha, H.; Jäger, Aleš; Knotek, P.; Tesař, Karel; Jarošová, Markéta; Macák, J. M.

    2016-01-01

    Roč. 190, Feb (2016), s. 744-752 ISSN 0013-4686 R&D Projects: GA ČR GBP108/12/G043 Institutional support: RVO:68378271 Keywords : titanium * anodization * titanium dioxide * nanotubes * ordering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.798, year: 2016

  12. High transmittance cadmium oxysulfide Cd(S,O) buffer layer grown by triton X-100 mediated chemical bath deposition for thin-film heterojunction solar cells

    Science.gov (United States)

    Ballipinar, Faruk; Rastogi, A. C.

    2017-01-01

    Polycrystalline 100-190 nm Cd(S,O) n-type semiconductor thin films of high transparency in the visible range are deposited by a surfactant Triton X-100 mediated chemical bath deposition process. The crystalline structure of the films revealed by X-ray diffraction data shows a cubic-CdO phase signified by (111) and (200) planes alongside the (002), (220), and (110) planes from hexagonal-CdS. The invariance of the 2θ position of the (002) CdS diffraction is interpreted in terms of the growth of the composite film essentially by the formation of a dilute interstitial alloy of CdO and CdS. This is confirmed by Raman spectra which, besides the CdS 1LO and 2LO modes at 300 and 600 cm-1, also show Raman lines from CdO at 1098 cm-1 and 952 cm-1 assigned as overtone of 2LO phonon modes and 556 cm-1 due to band crossing between LO and TO modes of CdO. Optical spectra of Cd(S,O) films show a median transmittance of >85% compared to ˜70% for CdS films in the 550-1000 nm wavelength range. The Cd(S,O) films show optical bandgap varying from 2.34 to 2.26 eV with increasing CdO fraction but retain high sub-bandgap transmission and sharp band edge threshold. The Cd(S,O) films thus offer an alternative to the CdS buffer layer in the heterojunction solar cells, which has major shortcoming of poor stability and high sub-bandgap absorption. The photoluminescence spectra of Cd(S,O) films show three green bands, of which one is the near band edge transition at 511.5 nm, the same as in CdS, the second band at 526.0 nm that red shifted from the CdS position is due to shallow donor-acceptor defects arising from structural change due to CdO, and the third band at 543.6 nm (2.28 eV) originates from direct band transition in CdO. The growth mechanism of Cd(S,O) films is described, which invokes that the Triton X-100 molecule modifies the microenvironment around adsorbed [Cd(NH3)4]2+ species, thereby inducing two concurrent reactions, one with SH- species that cause CdS formation and the

  13. A statistical approach for optimizing parameters for electrodeposition of indium (III) sulfide (In2S3) films, potential low-hazard buffer layers for photovoltaic applications

    Science.gov (United States)

    Mughal, Maqsood Ali

    Clean and environmentally friendly technologies are centralizing industry focus towards obtaining long term solutions to many large-scale problems such as energy demand, pollution, and environmental safety. Thin film solar cell (TFSC) technology has emerged as an impressive photovoltaic (PV) technology to create clean energy from fast production lines with capabilities to reduce material usage and energy required to manufacture large area panels, hence, lowering the costs. Today, cost ($/kWh) and toxicity are the primary challenges for all PV technologies. In that respect, electrodeposited indium sulfide (In2S3) films are proposed as an alternate to hazardous cadmium sulfide (CdS) films, commonly used as buffer layers in solar cells. This dissertation focuses upon the optimization of electrodeposition parameters to synthesize In2S3 films of PV quality. The work describe herein has the potential to reduce the hazardous impact of cadmium (Cd) upon the environment, while reducing the manufacturing cost of TFSCs through efficient utilization of materials. Optimization was performed through use of a statistical approach to study the effect of varying electrodeposition parameters upon the properties of the films. A robust design method referred-to as the "Taguchi Method" helped in engineering the properties of the films, and improved the PV characteristics including optical bandgap, absorption coefficient, stoichiometry, morphology, crystalline structure, thickness, etc. Current density (also a function of deposition voltage) had the most significant impact upon the stoichiometry and morphology of In2S3 films, whereas, deposition temperature and composition of the solution had the least significant impact. The dissertation discusses the film growth mechanism and provides understanding of the regions of low quality (for example, cracks) in films. In2S3 films were systematically and quantitatively investigated by varying electrodeposition parameters including bath

  14. Electrochemical detection of copper ions leached from CuO nanoparticles in saline buffers and biological media using a gold wire working electrode

    Energy Technology Data Exchange (ETDEWEB)

    Baldisserri, Carlo, E-mail: carlo.baldisserri@istec.cnr.it; Costa, Anna Luisa [ISTEC-CNR (Italy)

    2016-04-15

    We performed explorative cyclic voltammetry in phosphate-buffered saline buffers, Dulbecco’s modified Eagle’s medium (DMEM), and fetal bovine serum-added DMEM using Au wire as working electrode, both in the absence and in the presence of known nominal concentrations of Cu{sup 2+} ions or 15 nm CuO nanoparticles. Addition of either Cu{sup 2+} ions or aqueous suspension of CuO nanoparticles caused a single anodic peak to appear in the double-layer region of all three pristine media. The height of the anodic peak was found to increase in a monotonic fashion vs. Cu{sup 2+} concentration in Cu{sup 2+}-added media, and versus time since CuO addition in CuO-added media. Stepwise addition of glycine to Cu{sup 2+}-added phosphate-buffered saline buffer caused an increasing cathodic shift of the anodic peak accompanied by decreasing peak currents. Results indicate that preparing Cu{sup 2+}-free suspensions of CuO nanoparticles in such media is difficult, owing to the presence of leached copper ions. The implications on results of experiments in which CuO nanoparticle-added biological media are used as cell culture substrates are discussed. Literature data on the interactions between Cu{sup 2+} ions, dissolved carbon dioxide in aqueous CuO suspensions, and amino acids present in such media are compared to our results.

  15. Electrochemical detection of copper ions leached from CuO nanoparticles in saline buffers and biological media using a gold wire working electrode

    Science.gov (United States)

    Baldisserri, Carlo; Costa, Anna Luisa

    2016-04-01

    We performed explorative cyclic voltammetry in phosphate-buffered saline buffers, Dulbecco's modified Eagle's medium (DMEM), and fetal bovine serum-added DMEM using Au wire as working electrode, both in the absence and in the presence of known nominal concentrations of Cu2+ ions or 15 nm CuO nanoparticles. Addition of either Cu2+ ions or aqueous suspension of CuO nanoparticles caused a single anodic peak to appear in the double-layer region of all three pristine media. The height of the anodic peak was found to increase in a monotonic fashion vs. Cu2+ concentration in Cu2+-added media, and versus time since CuO addition in CuO-added media. Stepwise addition of glycine to Cu2+-added phosphate-buffered saline buffer caused an increasing cathodic shift of the anodic peak accompanied by decreasing peak currents. Results indicate that preparing Cu2+-free suspensions of CuO nanoparticles in such media is difficult, owing to the presence of leached copper ions. The implications on results of experiments in which CuO nanoparticle-added biological media are used as cell culture substrates are discussed. Literature data on the interactions between Cu2+ ions, dissolved carbon dioxide in aqueous CuO suspensions, and amino acids present in such media are compared to our results.

  16. Anodic growth of titanium dioxide nanostructures

    DEFF Research Database (Denmark)

    2010-01-01

    Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

  17. Band alignments of different buffer layers (CdS, Zn(O,S), and In2S3) on Cu2ZnSnS4

    Science.gov (United States)

    Yan, Chang; Liu, Fangyang; Song, Ning; Ng, Boon K.; Stride, John A.; Tadich, Anton; Hao, Xiaojing

    2014-04-01

    The heterojunctions of different n-type buffers, i.e., CdS, Zn(O,S), and In2S3 on p-type Cu2ZnSnS4 (CZTS) were investigated using X-ray Photoelectron Spectroscopy (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) Measurements. The band alignment of the heterojunctions formed between CZTS and the buffer materials was carefully measured. The XPS data were used to determine the Valence Band Offsets (VBO) of different buffer/CZTS heterojunctions. The Conduction Band Offset (CBO) was calculated indirectly by XPS data and directly measured by NEXAFS characterization. The CBO of the CdS/CZTS heterojunction was found to be cliff-like with CBOXPS = -0.24 ± 0.10 eV and CBONEXAFS = -0.18 ± 0.10 eV, whereas those of Zn(O,S) and In2S3 were found to be spike-like with CBOXPS = 0.92 ± 0.10 eV and CBONEXAFS = 0.87 ± 0.10 eV for Zn(O,S)/CZTS and CBOXPS = 0.41 ± 0.10 eV for In2S3/CZTS, respectively. The CZTS photovoltaic device using the spike-like In2S3 buffer was found to yield a higher open circuit voltage (Voc) than that using the cliff-like CdS buffer. However, the CBO of In2S3/CZTS is slightly higher than the optimum level and thus acts to block the flow of light-generated electrons, significantly reducing the short circuit current (Jsc) and Fill Factor (FF) and thereby limiting the efficiency. Instead, the use of a hybrid buffer for optimization of band alignment is proposed.

  18. Behavior of Photocarriers in the Light-Induced Metastable State in the p-n Heterojunction of a Cu(In,Ga)Se2 Solar Cell with CBD-ZnS Buffer Layer.

    Science.gov (United States)

    Lee, Woo-Jung; Yu, Hye-Jung; Wi, Jae-Hyung; Cho, Dae-Hyung; Han, Won Seok; Yoo, Jisu; Yi, Yeonjin; Song, Jung-Hoon; Chung, Yong-Duck

    2016-08-31

    We fabricated Cu(In,Ga)Se2 (CIGS) solar cells with a chemical bath deposition (CBD)-ZnS buffer layer grown with varying ammonia concentrations in aqueous solution. The solar cell performance was degraded with increasing ammonia concentration, due to actively dissolved Zn atoms during CBD-ZnS precipitation. These formed interfacial defect states, such as hydroxide species in the CBD-ZnS film, and interstitial and antisite Zn defects at the p-n heterojunction. After light/UV soaking, the CIGS solar cell performance drastically improved, with a rise in fill factor. With the Zn-based buffer layer, the light soaking treatment containing blue photons induced a metastable state and enhanced the CIGS solar cell performance. To interpret this effect, we suggest a band structure model of the p-n heterojunction to explain the flow of photocarriers under white light at the initial state, and then after light/UV soaking. The determining factor is a p+ defect layer, containing an amount of deep acceptor traps, located near the CIGS surface. The p+ defect layer easily captures photoexcited electrons, and then when it becomes quasi-neutral, attracts photoexcited holes. This alters the barrier height and controls the photocurrent at the p-n junction, and fill factor values, determining the solar cell performance.

  19. Investigation of magnetic interactions at Y3Fe5O12/ Gd3Ga5O12 interface by inserting a diamagnetic Y3Sc2Al3O12 buffer layer

    Science.gov (United States)

    Cheng, Yang; Lee, Aidan; Yu, Muqing; Brangham, Jack; Yang, Fengyuan

    Y3Fe5O12 (YIG) is a well-established material for microwave applications and pure spin transport. Gd3Ga5O12 (GGG) is a widely used substrate for epitaxial YIG film growth with very small lattice mismatch. Based on our recent study showing enhanced magnetization in YIG films, we suspect the strong Gd moment in GGG may couple to YIG and affect ferromagnetic resonance spin pumping. To probe this effect, we selected a lattice-matched diamagnetic buffer layer, Y3Sc2Al3O12 (YSAG), to decouple the potential magnetic interaction between YIG and GGG. Phase-pure YSAG powder, prepared by sol-gel synthesis, was made into a target for epitaxial growth of YSAG films on GGG using off-axis sputtering. X-ray diffraction revealed clear Laue oscillations and a narrow YSAG rocking curve of FWHM 0.0074 degrees, demonstrating high crystalline quality. In addition, the in-plane lattice constant of YSAG films is within 0.1% to those of GGG and YIG, making it an ideal buffer layer for this study. We then grow YIG films on YSAG buffered GGG, which show similarly high crystalline quality and ferromagnetic resonance properties to YIG films on GGG. We will also discuss dynamic spin transport studies using YIG/YSAG/GGG. NSF Grant No. DMR-1507274.

  20. Investigation of fundamental physical properties of CdSiP{sub 2} and its application in solar cell devices by using (ZnX; X = Se, Te) buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Verma, A.S., E-mail: ajay_phy@rediffmail.com [Department of Physics, Banasthali Vidyapith, Rajasthan 304022 (India); Gautam, Ruchita; Singh, Pravesh [Department of Physics, Banasthali Vidyapith, Rajasthan 304022 (India); Department of Electronics and Communication, Krishna Institute of Engineering and Technology, Ghaziabad, Uttar Pradesh 201206 (India); Sharma, Sheetal [Department of Physics, Swami Premanand Mahavidyalaya, Mukerian, Punjab 144211 (India); Kumari, Sarita [Department of Physics, University of Rajasthan, Jaipur 302004 (India)

    2016-03-15

    Graphical abstract: - Highlights: • FP-LAPW method has been used to compute the solid state properties of CdSiP{sub 2}. • Electronic and optical properties reported by WIEN2K with recently developed mBJ potential. • The elastic and thermal properties were evaluated by first principles calculations. • Hardness was calculated for the first time at different temperature and pressure. • Solar cell devices with ZnSe/ZnTe buffer layers by simulated work. - Abstract: The first principles calculations were performed by the linearized augmented plane wave (LAPW) method as implemented in the WIEN2K code within the density functional theory to obtain the structural, electronic and optical properties of CdSiP{sub 2} in the body centered tetragonal (BCT) phase. The six elastic constants (C{sub 11}, C{sub 12}, C{sub 13}, C{sub 33}, C{sub 44} and C{sub 66}) and mechanical parameters were presented and compared with the available experimental data. The thermodynamic calculations within the quasi-harmonic approximation is used to give an accurate description of the pressure-temperature dependence of the thermal-expansion coefficient, bulk modulus, specific heat, Debye temperature, entropy Grüneisen parameters and hardness. Further, CdSiP{sub 2} solar cell devices have been modeled; device physics and performance parameters are analyzed for zinc chalcogenide (ZnX; X = Se, Te) buffer layers. Simulation results for CdSiP{sub 2} thin layer solar cell show the maximum efficiency (25.7%) with ZnSe as the buffer layer.

  1. Influence of the Ti microstructure on anodic self-organized TiO.sub.2./sub. nanotube layers produced in ethylene glycol electrolytes.

    Czech Academy of Sciences Publication Activity Database

    Macák, J. M.; Jarošová, Markéta; Jäger, Aleš; Sopha, H.; Klementová, Mariana

    2016-01-01

    Roč. 371, May (2016), s. 607-612 ISSN 0169-4332 R&D Projects: GA ČR GBP108/12/G043; GA ČR(CZ) GA14-20744S Institutional support: RVO:68378271 ; RVO:61388980 Keywords : titanum * anodization * titanium dioxide * nanotubes * EBSD Subject RIV: BM - Solid Matter Physics ; Magnetism; CA - Inorganic Chemistry (UACH-T) Impact factor: 3.387, year: 2016

  2. Layered oxides-LiNi1/3Co1/3Mn1/3O2 as anode electrode for symmetric rechargeable lithium-ion batteries

    Science.gov (United States)

    Wang, Yuesheng; Feng, Zimin; Yang, Shi-Ze; Gagnon, Catherine; Gariépy, Vincent; Laul, Dharminder; Zhu, Wen; Veillette, René; Trudeau, Michel L.; Guerfi, Abdelbast; Zaghib, Karim

    2018-02-01

    High-performance and long-cycling rechargeable lithium-ion batteries have been in steadily increasing demand for the past decades. Nevertheless, the two dominant anodes at the moment, graphite and L4T5O12, suffer from a safety issue of lithium plating (operating voltage at ∼ 0.1 V vs. Li+/Li) and low capacity (175 mAh/g), respectively. Here, we report LiNi1/3Co1/3Mn1/3O2 as an alternative anode material which has a working voltage of ∼1.1 V and a capacity as high as 330 mAh/g at the current rate of C/15. Symmetric cells with both electrodes containing LiNi1/3Co1/3Mn1/3O2 can deliver average discharge voltage of 2.2 V. In-situ XRD, HRTEM and first principles calculations indicate that the reaction mechanism of a LiNi1/3Co1/3Mn1/3O2 anode is comprised mainly of conversion. Both the fundamental understanding and practical demonstrations suggest that LiNi1/3Co1/3Mn1/3O2 is a promising negative electrode material for lithium-ion batteries.

  3. Kinetic buffers.

    Science.gov (United States)

    Alibrandi, Giuseppe; Fabbrizzi, Luigi; Licchelli, Maurizio; Puglisi, Antonio

    2015-01-12

    This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. An evaluation of phase separated, self-assembled LaMnO3-MgO nanocomposite films directly on IBAD-MgO as buffer layers for flux pinning enhancements in YBa2YCu3O7-& coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Ozgur [ORNL; Aytug, Tolga [ORNL; Paranthaman, Mariappan Parans [ORNL; Leonard, Keith J [ORNL; Lupini, Andrew R [ORNL; Pennycook, Stephen J [ORNL; Meyer III, Harry M [ORNL; Kim, Kyunghoon [ORNL; Qiu, Xiaofeng [ORNL; Cook, Sylvester W [ORNL; Thompson, James R [ORNL; Christen, David K [ORNL; Goyal, Amit [ORNL; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Xiong, X. [SuperPower Incorporated, Schenectady, New York

    2010-01-01

    Technological applications of high temperature superconductors (HTS) require high critical current density, Jc, under operation at high magnetic field strengths. This requires effective flux pinning by introducing artificial defects through creative processing. In this work, we evaluated the feasibility of mixed-phase LaMnO3:MgO (LMO:MgO) films as a potential cap buffer layer for the epitaxial growth and enhanced performance of YBa2Cu3O7-d (YBCO) films. Such composite films were sputter deposited directly on IBAD-MgO templates (with no additional homo-epitaxial MgO layer) and revealed the formation of two phase-separated, but at the same time vertically aligned, self-assembled composite nanostructures that extend throughout the entire thickness of the film. The YBCO coatings deposited on these nanostructured cap layers showed correlated c-axis pinning and improved in-field Jc performance compared to those of YBCO films fabricated on standard LMO buffers. Microstructural characterization revealed additional extended disorder in the YBCO matrix. The present results demonstrate the feasibility of novel and potentially practical approaches in the pursuit of more efficient, economical, and high performance superconducting devices.

  5. Electrically Conductive Anodized Aluminum Surfaces

    Science.gov (United States)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  6. Structural study of ZnSe films grown on substrate with In{sub x}Ga{sub 1-x}As and Al{sub 1-x}Ga{sub x}As buffer layers: strain, relaxation and lattice parameter

    Energy Technology Data Exchange (ETDEWEB)

    Perez Ladron de Guevara, H.; Gaona-Couto, A.; Vidal, M.A. [Instituto de Investigacion En Comunicacion Optica (IICO), Universidad Autonoma de San Luis Potosi, San Luis Potosi (Mexico)]. E-mail: mavidal@cactus.iico.uaslp.mx; Luyo Alvarado, J.; Melendez Lira, M.; Lopez-Lopez, M. [Departamento de Fisica, Centro de Investigacion y Estudios Avanzados del IPN, Mexico DF (Mexico)

    2002-06-21

    ZnSe layers of various thickness were grown on (001) GaAs substrates, using In{sub x}Ga{sub 1-x}As or Al{sub 1-x}Ga{sub x}As as buffer layers by molecular beam epitaxy and were studied by high-resolution x-ray diffraction. The principal structural characteristics of ZnSe layer and buffer layer were determined using several reflections, such as (004) and two pairs of coupled asymmetric reflections, namely (224), (-2-24) and (115) (-1-15). In order to evaluate their validity, the experimental data obtained from these reflections were handled by means of two known expressions found in the literature. We have found the relaxation process of ZnSe layers is well described by a geometrical model including the thermal strain and small strain due to work hardening. The relaxation process is faster for ZnSe grown on ternary buffer layers despite the fact that, some buffer layers are pseudomorphically grown to the substrate; therefore we conclude that not only the lattice mismatches have effect on the relaxation process but also the surface state of the buffer layer has an influence in this process. (author)

  7. Interface characteristics of spin-on-dielectric SiOx-buffered passivation layers for AlGaN/GaN high electron mobility transistors

    International Nuclear Information System (INIS)

    Ko, Pil-Seok; Park, Kyoung-Seok; Yoon, Yeo-Chang; Sheen, Mi-Hyang; Kim, Sam-Dong

    2015-01-01

    To reveal the cause for significant enhancement of dc current performance of the AlGaN/GaN high electron mobility transistors (HEMTs) with the spin-on-dielectric (SOD) SiO x -buffered passivation structure compared to the conventional Si 3 N 4 passivation deposited by plasma-enhanced vapor deposition (PECVD), we characterized the passivation interfaces using the cross-sectional transmission electron microscopy, cathodoluminescence, capacitance–voltage (C–V) characterizations, and Hall-effect measurements. The interface state density of PECVD Si 3 N 4 passivation was in the range of 10 12 –10 13 cm −2 eV −1 , which is one-order higher than that of the SOD (10 11 –10 12 cm −2 eV −1 ) as measured by C–V measurements from the metal–insulator–semiconductor capacitors. Higher density of effective oxide charge density (especially dominant contribution of ionic mobile charge) was also derived from the PECVD Si 3 N 4 passivation. A well-resolved reduction of the electron Hall mobility of the Si 3 N 4 passivation compared to that of the perhydropolysilazane SOD passivation, which can be due to the higher-density interface states and trap charges, can answer the relative dc current collapse of our HEMT devices. - Highlights: • Spin-on-dielectric (SOD)-buffered passivation for AlGaN/GaN HEMTs • Characterize the charge density and interface states using the C–V measurements • SOD-buffered passivation minimizes surface states at the interface. • DC performance of SOD-buffered structure is due to the interface characteristics

  8. Interface characteristics of spin-on-dielectric SiO{sub x}-buffered passivation layers for AlGaN/GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Pil-Seok; Park, Kyoung-Seok; Yoon, Yeo-Chang [Division of Electronics and Electrical Engineering, Dongguk University, 100-715 Seoul (Korea, Republic of); Sheen, Mi-Hyang [Department of Materials Science Engineering, Seoul National University, 151-742 Seoul (Korea, Republic of); Kim, Sam-Dong, E-mail: samdong@dongguk.edu [Division of Electronics and Electrical Engineering, Dongguk University, 100-715 Seoul (Korea, Republic of)

    2015-08-31

    To reveal the cause for significant enhancement of dc current performance of the AlGaN/GaN high electron mobility transistors (HEMTs) with the spin-on-dielectric (SOD) SiO{sub x}-buffered passivation structure compared to the conventional Si{sub 3}N{sub 4} passivation deposited by plasma-enhanced vapor deposition (PECVD), we characterized the passivation interfaces using the cross-sectional transmission electron microscopy, cathodoluminescence, capacitance–voltage (C–V) characterizations, and Hall-effect measurements. The interface state density of PECVD Si{sub 3}N{sub 4} passivation was in the range of 10{sup 12}–10{sup 13} cm{sup −2} eV{sup −1}, which is one-order higher than that of the SOD (10{sup 11}–10{sup 12} cm{sup −2} eV{sup −1}) as measured by C–V measurements from the metal–insulator–semiconductor capacitors. Higher density of effective oxide charge density (especially dominant contribution of ionic mobile charge) was also derived from the PECVD Si{sub 3}N{sub 4} passivation. A well-resolved reduction of the electron Hall mobility of the Si{sub 3}N{sub 4} passivation compared to that of the perhydropolysilazane SOD passivation, which can be due to the higher-density interface states and trap charges, can answer the relative dc current collapse of our HEMT devices. - Highlights: • Spin-on-dielectric (SOD)-buffered passivation for AlGaN/GaN HEMTs • Characterize the charge density and interface states using the C–V measurements • SOD-buffered passivation minimizes surface states at the interface. • DC performance of SOD-buffered structure is due to the interface characteristics.

  9. N-doped carbon coated anatase TiO2 nanoparticles as superior Na-ion battery anodes.

    Science.gov (United States)

    Wang, Jin; Liu, Guiyu; Fan, Kaili; Zhao, Dan; Liu, Beibei; Jiang, Jianbo; Qian, Dong; Yang, Chunming; Li, Junhua

    2018-05-01

    N-doped carbon coated TiO 2 nanoparticles (TiO 2 @NC) were synthesized through a simple two-step route, in which dopamine was simultaneously utilized as both nitrogen and carbon sources. With TiO 2 @NC applied in the Na-ion battery (SIB) anodes, the continuous and uniform N-doped carbon layer can not only enhance the electrical conductivity of TiO 2 and facilitate the surface pseudocapacitive process, but also serve as a buffer layer to accommodate the volume expansion during the sodiation-desodiation processes. The as-prepared TiO 2 @NC exhibits excellent electrochemical performance when utilized as the SIB anodes, which delivers a remarkably high reversible capacity of 250.2 mAh g -1 at a rate of 0.25C (84 mA g -1 ) after 200 cycles and still retains 122.1 mAh g -1 at 10C (3.35 A g -1 ) even after 3000 cycles accompanied with a 95.3% retention of the maximum capacity, outperforming most of the reported TiO 2 /C-based composites as SIB anodes. To our best knowledge, the preparation of TiO 2 @NC with dopamine as both nitrogen and carbon sources and its application in the SIB anodes are reported for the first time. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Photocatalytic effect of anodic titanium oxide nanotubes on various cell culture media

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Chun-Kang; Hu, Kan-Hung; Wang, Shing-Hoa [National Taiwan Ocean University, Center for Marine Bioenvironment and Biotechnology, Keelung (China); National Taiwan Ocean University, Department of Mechanical and Mechatronic Engineering, Keelung (China); Hsu, Todd [National Taiwan Ocean University, Center for Marine Bioenvironment and Biotechnology, Keelung (China); National Taiwan Ocean University, Institute of Bioscience and Biotechnology, Keelung (China); Tsai, Huei-Ting [National Taiwan Ocean University, Institute of Bioscience and Biotechnology, Keelung (China); Chen, Chien-Chon [National United University, Department of Energy and Resources, Miaoli (China); Liu, Shiu-Mei [National Taiwan Ocean University, Center for Marine Bioenvironment and Biotechnology, Keelung (China); National Taiwan Ocean University, Institute of Marine Biology, Keelung (China); Lin, Tai-Yuan [National Taiwan Ocean University, Institute of Optoelectronic Sciences, Keelung (China); Chen, Chin-Hsing [National Chiao Tong University, Department of Applied Chemistry, Hsinchu (China)

    2011-02-15

    The use of titanium dioxide (TiO{sub 2}) in photodynamic therapy for the treatment of cancer cells has been proposed following studies of cultured cancer cells. In this work, an ordered channel array of anodic titanium oxide (ATO) was fabricated by anodizing titanium foil. The ATO layer of nanotubes with diameters of 100 nm was made in NH{sub 4}F electrolyte by anodization. The photocatalytic effect of ATO was examined on various culture media by ultraviolet A (UV-A) (366 nm) irradiation. After UV-A irradiation of the ATO layer, redox potential of Tris-HCl buffer (pH 7.5) and dilute acrylamide solution increased instantaneously. The redox potential of the serum-containing RPMI1640 medium also increased dramatically, while that of serum-containing MEM and DMEM media increased slightly. The UVA-induced high redox potential was correlated with the greater ability to break down plasmid DNA strands. These phenomena suggest that a culture medium, such as RPMI1640, with a greater ability to produce free radical may be associated with a stronger photocatalytic effect of ATO on cultured cancer cells reported previously. (orig.)

  11. Terahertz radiation in In{sub 0.38}Ga{sub 0.62}As grown on a GaAs wafer with a metamorphic buffer layer under femtosecond laser excitation

    Energy Technology Data Exchange (ETDEWEB)

    Ponomarev, D. S., E-mail: ponomarev-dmitr@mail.ru; Khabibullin, R. A.; Yachmenev, A. E.; Maltsev, P. P. [Russian Academy of Sciences, Institute of Ultrahigh Frequency Semiconductor Electronics (Russian Federation); Grekhov, M. M. [National Research Nuclear University “MEPhI” (Russian Federation); Ilyakov, I. E.; Shishkin, B. V.; Akhmedzhanov, R. A. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2017-04-15

    The results of time-domain spectroscopy of the terahertz (THz) generation in a structure with an In{sub 0.38}Ga{sub 0.62}As photoconductive layer are presented. This structure grown by molecular-beam epitaxy on a GaAs substrate using a metamorphic buffer layer allows THz generation with a wide frequency spectrum (to 6 THz). This is due to the additional contribution of the photo-Dember effect to THz generation. The measured optical-to-terahertz conversion efficiency in this structure is 10{sup –5} at a rather low optical fluence of ~40 μJ/cm{sup 2}, which is higher than that in low-temperature grown GaAs by almost two orders of magnitude.

  12. UV-ozone-treated MoO3 as the hole-collecting buffer layer for high-efficiency solution-processed SQ:PC71BM photovoltaic devices

    Science.gov (United States)

    Yang, Qian-Qian; Yang, Dao-Bin; Zhao, Su-Ling; Huang, Yan; Xu, Zheng; Gong, Wei; Fan, Xing; Liu, Zhi-Fang; Huang, Qing-Yu; Xu, Xu-Rong

    2014-03-01

    The enhanced performance of a squaraine compound, with 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine as the donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor, in solution-processed organic photovoltaic devices is obtained by using UV-ozone-treated MoO3 as the hole-collecting buffer layer. The optimized thickness of the MoO3 layer is 8 nm, at which the device shows the best power conversion efficiency (PCE) among all devices, resulting from a balance of optical absorption and charge transport. After being treated by UV-ozone for 10 min, the transmittance of the MoO3 film is almost unchanged. Atomic force microscopy results show that the treated surface morphology is improved. A high PCE of 3.99% under AM 1.5 G illumination (100 mW/cm2) is obtained.

  13. Novel oxide buffer approach for GaN integration on Si(111) platform through Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} bi-layer

    Energy Technology Data Exchange (ETDEWEB)

    Tarnawska, Lidia

    2012-12-19

    Motivation: Preparation of GaN virtual substrates on large-scale Si wafers is intensively pursued as a cost-effective approach for high power/high frequency electronics (HEMT's etc.) and optoelectronic applications (LED, LASER). However, the growth of high quality GaN layers on Si is hampered by several difficulties mainly related to a large lattice mismatch (-17%) and a huge difference in the thermal expansion coefficient (56%). As a consequence, GaN epitaxial layers grown on Si substrates show a high number of defects (threading dislocations etc.), which severely deteriorate the overall quality of the GaN films. Additionally, due to the different thermal expansion coefficients of the substrate and the film, um-thick GaN layers crack during post-growth cooling. To solve these integration problems, different semiconducting (e.g. AlN, GaAs, ZnO, HfN) and insulating (e.g. Al{sub 2}O{sub 3}, MgO, LiGaO{sub 2}) buffer layers, separating the Si substrate from the GaN film, are applied. Goal: In this thesis, a novel buffer approach for the integration of GaN on Si is proposed and investigated. The new approach employs Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} bilayer templates as a step-graded buffer to reduce the lattice mismatch between GaN and the Si(111) substrate. According to the bulk crystal lattices, since the Y{sub 2}O{sub 3} has an in-plane lattice misfit of -2% to Si, Sc{sub 2}O{sub 3} -7% to Y{sub 2}O{sub 3}, the lattice misfit between GaN and the substrate can be theoretically reduced by about 50% from -17% (GaN/Si) to -8% (GaN/Sc{sub 2}O{sub 3}). Experimental: The GaN/Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) heterostructures are prepared in a multichamber molecular beam epitaxy system on 4 inch Si(111) wafers. In order to obtain complete information on the structural quality of the oxide buffer as well as the GaN layer, synchrotron- and laboratory-based X-ray diffraction, transmission electron microscopy and photoluminescence measurements are performed. The

  14. Amorphous silicon-carbon based nano-scale thin film anode materials for lithium ion batteries

    International Nuclear Information System (INIS)

    Datta, Moni Kanchan; Maranchi, Jeffrey; Chung, Sung Jae; Epur, Rigved; Kadakia, Karan; Jampani, Prashanth; Kumta, Prashant N.

    2011-01-01

    Research highlights: → Thin film amorphous C/Si. Good cycling response validates carbon matrix for Silicon anodes. → Thin film amorphous C/Si/C. Good cycling response validates carbon as an interface and matrix. - Abstract: The buffering effect of carbon on the structural stability of amorphous silicon films, used as an anode for lithium ion rechargeable batteries, has been studied during long term discharge/charge cycles. To this extent, the electrochemical performance of a prototype material consisting of amorphous Si thin film (∼250 nm) deposited by radio frequency magnetron sputtering on amorphous carbon (∼50 nm) thin films, denoted as a-C/Si, has been investigated. In comparison to pure amorphous Si thin film (a-Si) which shows a rapid fade in capacity after 30 cycles, the a-C/Si exhibits excellent capacity retention displaying ∼0.03% fade in capacity up to 50 cycles and ∼0.2% after 50 cycles when cycled at a rate of 100 μA/cm 2 (∼C/2) suggesting that the presence of thin amorphous C layer deposited between the Cu substrate and a-Si acts as a buffer layer facilitating the release of the volume induced stresses exhibited by pure a-Si during the charge/discharge cycles. This structural integrity combined with microstructural stability of the a-C/Si thin film during the alloying/dealloying process with lithium has been confirmed by scanning electron microscopy (SEM) analysis. The buffering capacity of the thin amorphous carbon layer lends credence to its use as the likely compliant matrix to curtail the volume expansion related cracking of silicon validating its choice as the matrix for bulk and thin film battery systems.

  15. Anodic etching of GaN based film with a strong phase-separated InGaN/GaN layer: Mechanism and properties

    International Nuclear Information System (INIS)

    Gao, Qingxue; Liu, Rong; Xiao, Hongdi; Cao, Dezhong; Liu, Jianqiang; Ma, Jin

    2016-01-01

    Highlights: • GaN film with a strong phase-separated InGaN/GaN layer was etched by electrochemical etching. • Vertically aligned nanopores in n-GaN films were buried underneath the InGaN/GaN structures. • The relaxation of compressive stress in the MQW structure was found by PL and Raman spectra. - Abstract: A strong phase-separated InGaN/GaN layer, which consists of multiple quantum wells (MQW) and superlattices (SL) layers and can produce a blue wavelength spectrum, has been grown on n-GaN thin film, and then fabricated into nanoporous structures by electrochemical etching method in oxalic acid. Scanning electron microscopy (SEM) technique reveals that the etching voltage of 8 V leads to a vertically aligned nanoporous structure, whereas the films etched at 15 V show branching pores within the n-GaN layer. Due to the low doping concentration of barriers (GaN layers) in the InGaN/GaN layer, we observed a record-low rate of etching (<100 nm/min) and nanopores which are mainly originated from the V-pits in the phase-separated layer. In addition, there exists a horizontal nanoporous structure at the interface between the phase-separated layer and the n-GaN layer, presumably resulting from the high transition of electrons between the barrier and the well (InGaN layer) at the interface. As compared to the as-grown MQW structure, the etched MQW structure exhibits a photoluminescence (PL) enhancement with a partial relaxation of compressive stress due to the increased light-extracting surface area and light-guiding effect. Such a compressive stress relaxation can be further confirmed by Raman spectra.

  16. Anodic etching of GaN based film with a strong phase-separated InGaN/GaN layer: Mechanism and properties

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Qingxue [School of Physics, Shandong University, Jinan, 250100 (China); Liu, Rong [Department of Fundamental Theories, Shandong Institute of Physical Education and Sports, Jinan 250063 (China); Xiao, Hongdi, E-mail: hdxiao@sdu.edu.cn [School of Physics, Shandong University, Jinan, 250100 (China); Cao, Dezhong; Liu, Jianqiang; Ma, Jin [School of Physics, Shandong University, Jinan, 250100 (China)

    2016-11-30

    Highlights: • GaN film with a strong phase-separated InGaN/GaN layer was etched by electrochemical etching. • Vertically aligned nanopores in n-GaN films were buried underneath the InGaN/GaN structures. • The relaxation of compressive stress in the MQW structure was found by PL and Raman spectra. - Abstract: A strong phase-separated InGaN/GaN layer, which consists of multiple quantum wells (MQW) and superlattices (SL) layers and can produce a blue wavelength spectrum, has been grown on n-GaN thin film, and then fabricated into nanoporous structures by electrochemical etching method in oxalic acid. Scanning electron microscopy (SEM) technique reveals that the etching voltage of 8 V leads to a vertically aligned nanoporous structure, whereas the films etched at 15 V show branching pores within the n-GaN layer. Due to the low doping concentration of barriers (GaN layers) in the InGaN/GaN layer, we observed a record-low rate of etching (<100 nm/min) and nanopores which are mainly originated from the V-pits in the phase-separated layer. In addition, there exists a horizontal nanoporous structure at the interface between the phase-separated layer and the n-GaN layer, presumably resulting from the high transition of electrons between the barrier and the well (InGaN layer) at the interface. As compared to the as-grown MQW structure, the etched MQW structure exhibits a photoluminescence (PL) enhancement with a partial relaxation of compressive stress due to the increased light-extracting surface area and light-guiding effect. Such a compressive stress relaxation can be further confirmed by Raman spectra.

  17. Ellipsometry of anodic film growth

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.G.

    1978-08-01

    An automated computer interpretation of ellisometer measurements of anodic film growth was developed. Continuous mass and charge balances were used to utilize more fully the time dependence of the ellipsometer data and the current and potential measurements. A multiple-film model was used to characterize the growth of films which proceeds via a dissolution--precipitation mechanism; the model also applies to film growth by adsorption and nucleation mechanisms. The characteristic parameters for film growth describe homogeneous and heterogeneous crystallization rates, film porosities and degree of hydration, and the supersaturation of ionic species in the electrolyte. Additional descriptions which may be chosen are patchwise film formation, nonstoichiometry of the anodic film, and statistical variations in the size and orientation of secondary crystals. Theories were developed to describe the optical effects of these processes. An automatic, self-compensating ellipsometer was used to study the growth in alkaline solution of anodic films on silver, cadmium, and zinc. Mass-transport conditions included stagnant electrolyte and forced convection in a flow channel. Multiple films were needed to characterize the optical properties of these films. Anodic films grew from an electrolyte supersatuated in the solution-phase dissolution product. The degree of supersaturation depended on transport conditions and had a major effect on the structure of the film. Anodic reaction rates were limited by the transport of charge carriers through a primary surface layer. The primary layers on silver, zinc, and cadmium all appeared to be nonstoichiometric, containing excess metal. Diffusion coefficients, transference numbers, and the free energy of adsorption of zinc oxide were derived from ellipsometer measurements. 97 figures, 13 tables, 198 references.

  18. Anodization and Optical Appearance of Sputter Deposited Al-Zr Coatings

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara

    2014-01-01

    Anodized Al alloy components are extensively used in various applications like architectural, decorative and automobiles for corrosion protection and/or decorative optical appearance. However, tailoring the anodized layer for specific optical appearance is limited due to variation in composition...

  19. FLUORINE CELL ANODE ASSEMBLY

    Science.gov (United States)

    Cable, R.E.; Goode, W.B. Jr.; Henderson, W.K.; Montillon, G.H.

    1962-06-26

    An improved anode assembly is deslgned for use in electrolytlc cells ln the productlon of hydrogen and fluorlne from a moIten electrolyte. The anode assembly comprises a copper post, a copper hanger supported by the post, a plurality of carbon anode members, and bolt means for clamplng half of the anode members to one slde of the hanger and for clamplng the other half of the anode members to the other slde of the hanger. The heads of the clamplng bolts are recessed withln the anode members and carbon plugs are inserted ln the recesses above the bolt heads to protect the boIts agalnst corroslon. A copper washer is provided under the head of each clamplng boIt such that the anode members can be tightly clamped to the hanger with a resultant low anode jolnt resistance. (AEC)

  20. Uncovering a new quasi-2D CuO2 plane between the YBa2Cu3O7 and CeO2 buffer layer of coated conductors

    Science.gov (United States)

    Li, Zhi-Xin; Cao, Jin-Jin; Gou, Xiao-Fan; Wang, Tian-Ge; Xue, Feng

    2018-01-01

    We report a discovery of the quasi-two-dimensional (quasi-2D) CuO2 plane between the superconductor YBa2Cu3O7 (YBCO) and CeO2 buffer layer (mostly used in the fabrication) of coated conductors through the atomistic computer simulations with the molecular dynamics (MD) and first-principle calculations. For an YBCO coated conductor with multilayer structures, the buffer layers deposited onto a substrate are mainly considered to transfer a strong biaxial texture from the substrate to the YBCO layer. To deeply understand the tuning mechanism of the texture transfer, exploring the complete atomic-level picture of the structure between the YBa2Cu3O7/CeO2 interfaces is firstly required. However, the related observation data have not been available due to some big challenges of experimental techniques. With the MD simulations, having tested the accuracy of the potential functions for the YBa2Cu3O7/CeO2 interface, we constructed a total of 54 possible atom stacking models of the interface and identified its most appropriate and stable structure according to the criterion of the interface adhesion energy and the coherent characterization. To further verify the stability of the identified structure, we performed the first-principle calculations to obtain the adhesion energy and developed the general knowledge of the interface structure. Finally, a coherent interface formed with a new built quasi-2D CuO2 plane that is structurally similar to the CuO2 plane inside bulk YBCO was determined.

  1. Development of all chemical solution derived Ce0.9La0.1O2−y/Gd2Zr2O7 buffer layer stack for coated conductors: influence of the post-annealing process on surface crystallinity

    International Nuclear Information System (INIS)

    Zhao, Y; Li, X-F; He, D; Andersen, N H; Grivel, J-C; Khoryushin, A; Hansen, J B

    2012-01-01

    Preparation and characterization of a biaxially textured Gd 2 Zr 2 O 7 and Ce 0.9 La 0.1 O 2−y (CLO, cap)/Gd 2 Zr 2 O 7 (GZO, barrier) buffer layer stack by the metal–organic deposition route are reported. YBa 2 Cu 3 O 7−d (YBCO) superconductor films were deposited by the pulsed-laser deposition (PLD) technique to assess the efficiency of such a novel buffer layer stack. Biaxial texture quality and morphology of the buffer layers and the YBCO superconductor films were fully characterized. The surface crystallinity of the buffer layers is studied by the electron backscatter diffraction technique. It is revealed that post-annealing GZO films in 2% H 2 in Ar is an effective way to improve the surface crystallinity. As a result, a highly textured CLO film can grow directly on the GZO film at a lower crystallization temperature. The critical current density of a YBCO PLD film is higher than 1 MA cm −2 (77 K, in self-field), demonstrating that the novel CLO/GZO stack is very promising for further development of low cost buffer layer architectures for coated conductors.

  2. Controlling Piezoelectric Responses in Pb(Zr0.52Ti0.48)O3 Films through Deposition Conditions and Nanosheet Buffer Layers on Glass

    NARCIS (Netherlands)

    Nguyen, Minh D.; Houwman, Evert P.; Yuan, Huiyu; Wylie- Van Eerd, Benjamin; Dekkers, Matthijn; Koster, Gertjan; Ten Elshof, Johan E.; Rijnders, Guus

    2017-01-01

    Nanosheet Ca2Nb3O10 (CNOns) layers were deposited on ultralow expansion glass substrates by the Langmuir-Blodgett method to obtain preferential (001)-oriented growth of Pb(Zr0.52Ti0.48)O3 (PZT) thin films using pulsed laser deposition (PLD) to enhance the ferroelectric and piezoelectric properties

  3. Electro-optic properties of epitaxial Sr0.6Ba0.4Nb2O6 films grown on MgO substrates using LixNi2-xO buffer layer

    Science.gov (United States)

    Li, X. T.; Du, P. Y.; Ye, H.; Mak, C. L.; Wong, K. H.

    2008-08-01

    Textured LixNi2-xO (LNO) thin films have been fabricated on (001)MgO substrates by pulsed laser deposition technique. The as-deposited LNO films shows a conductivity of 2.5×10-3 Ω m and possess a transmittance of about 35% in the visible region. Subsequent deposition of Sr0.6Ba0.4Nb2O6 (SBN60) thin film on these LNO-coated MgO substrates resulted in a textured SBN layer with a orientation perpendicular to the substrate plane. Phi scans on the (221) plane of the SBN layer indicated that the films have two in-plane orientations with respect to the substrate. The SBN unit cells were rotated in the plane of the film by ± 8.2° as well as ± 45° with respect to the LNO/MgO substrate. Besides the highly (00l)-orientation, the SBN films also exhibited a dense microstructure as shown by scanning electron microscopy. The electro-optic coefficient (r33) of the SBN film was measured to be 186 pm/V. On the basis of our results, we have demonstrated that the LNO film can be used as a buffer layer as well as a transparent bottom electrode for waveguide applications. The SBN/LNO heterostructure is also a suitable candidate for integrated electro-optics devices.

  4. Battery, especially for portable devices, has an anode containing silicon

    OpenAIRE

    Kan, S.Y.

    2002-01-01

    The anode (2) contains silicon. A battery with a silicon-containing anode is claimed. An Independent claim is also included for a method used to make the battery, comprising the doping of a silicon substrate (1) with charge capacity-increasing material (preferably boron, phosphorous or arsenic), etching the doped substrate layer in order to increase its porosity, and applying a cathode (3) in the form of a lithium oxide compound onto the resulting anode and applying an electrolyte (4) to the ...

  5. Buffer layer ZnO-assistant fabrication of c-axis GaN films by using pulsed laser deposition on Si(111) substrate: annealing effects in ammonia ambience

    Science.gov (United States)

    Man, B. Y.; Wei, J.; Yang, C.; Chen, C. S.; Liu, M.

    2009-09-01

    ZnO buffer layers have been used to fabricate GaN thin films by using pulsed laser deposition on Si (111) substrates. c-axis GaN thin films were obtained by annealing in NH3 atmosphere at 950°C for 15 min. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) have been used for the characterizations of the crystalline quality, composition, and surface morphology of the films. The annealing in ammonia (NH3) atmosphere markedly affects the preparation of GaN films and the least annealing time is 15 min under our experimental conditions. The mechanism of the effects of the ZnO buffer layers was studied. In the beginning, Zn-O bonds are destroyed in the interface of the films; a few O and Zn atoms depart from their positions, while N and Ga atoms fill in the empty positions and form a hexagonal structure of a special component. Many bonds (such as Ga-O bonds, Zn-N bonds) existed then. The number of Zn-O bonds decreases and the number of Ga-N bonds increases in the films with increasing of the annealing time. Many other bonds (such as Ga-O bonds, Zn-N bonds) also decreased and more Ga-N bonds formed with annealing time increasing. After having been annealed for 15 min under our experimental conditions, the quality of the hexagonal structure GaN films was markedly improved by the destroying of the Zn-O bonds during high-temperature annealing.

  6. Single layers of WS2 nanoplates embedded in nitrogen-doped carbon nanofibers as anode materials for lithium-ion batteries

    Science.gov (United States)

    Yu, Sunmoon; Jung, Ji-Won; Kim, Il-Doo

    2015-07-01

    Single layers of WS2 nanoplates are uniformly embedded in nitrogen-doped carbon nanofibers (WS2@NCNFs) via a facile electrospinning method. Crystallization of the single-layered WS2 nanoplates and in situ nitrogen doping into the carbon nanofibers were simultaneously accomplished during a two-step heat treatment. The distinctive structure of the WS2@NCNFs enables outstanding electrochemical performances.Single layers of WS2 nanoplates are uniformly embedded in nitrogen-doped carbon nanofibers (WS2@NCNFs) via a facile electrospinning method. Crystallization of the single-layered WS2 nanoplates and in situ nitrogen doping into the carbon nanofibers were simultaneously accomplished during a two-step heat treatment. The distinctive structure of the WS2@NCNFs enables outstanding electrochemical performances. Electronic supplementary information (ESI) available: Experimental section, SEM images of WS2 powder and ground WS2 powder, TEM image and SAED pattern of the WS2 powder, Raman spectra of the WS2 powder, CV curves of the WS2 powder, voltage profiles of the WS2 powder, schematic diagram of WS2@NCNFs undergoing lithium storage reactions, electrochemical performance of NCNFs, morphologies and EDS mapping of WS2@NCNFs after cycling, and a table of contributions of NCNFs to the specific capacity. See DOI: 10.1039/c5nr02425k

  7. Enhanced photocatalytic activity of hydrogenated and vanadium doped TiO2 nanotube arrays grown by anodization of sputtered Ti layers

    Science.gov (United States)

    Motola, Martin; Satrapinskyy, Leonid; Čaplovicová, Mária; Roch, Tomáš; Gregor, Maroš; Grančič, Branislav; Greguš, Ján; Čaplovič, Ľubomír; Plesch, Gustav

    2018-03-01

    TiO2 nanotube (TiNT) arrays were grown on silicon substrate via electrochemical anodization of titanium films sputtered by magnetron. To improve the photocatalytic activity of arrays annealed in air (o-TiNT), doping of o-TiNT with vanadium was performed (o-V/TiNT). These non-doped and doped TiNT arrays were also hydrogenated in H2/Ar atmosphere to r-TiNT and r-V/TiNT samples, respectively. Investigation of composition and morphology by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS) showed the presence of well-ordered arrays of anatase nanotubes with average diameter and length of 100 nm and 1.3 μm, respectively. In both oxidized and reduced V-doped samples, vanadium is partly dissolved in the structure of anatase and partly deposited in form of oxide on the nanotube surface. Vanadium-doped and reduced samples exhibited higher rates in the photodegradation of organic dyes (compared to non-modified o-TiNT sample) and this is caused by limitation of electron-hole recombination rates and by shift of the energy gap into visible region. The photocatalytic activity was measured under UV, sunlight and visible irradiation, and the corresponding efficiency increased in the order (o-TiNT) < (r-TiNT) < (o-V/TiNT) < (r-V/TiNT). Under visible light, only r-TiNT and r-V/TiNT showed significant photocatalytic activity.

  8. Electrometallurgy of copper refinery anode slimes

    Science.gov (United States)

    Scott, J. D.

    1990-08-01

    High-selenium copper refinery anode slimes form two separate and dynamically evolving series of compounds with increasing electrolysis time. In one, silver is progressively added to non-stoichiometric copper selenides, both those originally present in the anode and those formed subsequently in the slime layer, and in the other, silver-poor copper selenides undergo a dis-continuous crystallographic sequence of anodic-oxidative transformations. The silver-to-selenium molar ratio in the as-cast anode and the current density of electrorefining can be used to construct predominance diagrams for both series and, thus, to predict the final bulk “mineralogy” of the slimes. Although totally incorrect in detail, these bulk data are sufficiently accurate to provide explanations for several processing problems which have been experienced by Kidd Creek Division, Falconbridge Ltd., in its commercial tankhouse. They form the basis for a computer model which predicts final cathode quality from chemical analyses of smelter feed.

  9. LaNiO{sub 3} buffer layers for high critical current density YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} films

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-10-01

    We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5 K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both {ital a}-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. {copyright} {ital 1999 American Institute of Physics.}

  10. Carbon nanotubes-bridged molybdenum trioxide nanosheets as high performance anode for lithium ion batteries

    Science.gov (United States)

    Sun, Haiyan; Hanlon, Damien; Dinh, Duc Anh; Boland, John B.; Esau Del Rio Castillo, Antonio; Di Giovanni, Carlo; Ansaldo, Alberto; Pellegrini, Vittorio; Coleman, Jonathan N.; Bonaccorso, Francesco

    2018-01-01

    The search for novel nanomaterials driving the development of high-performance electrodes in lithium ion batteries (LIBs) is at the cutting edge of research in the field of energy storage. Here, we report on the synthesis of single wall carbon nanotube (SWNT)-bridged molybdenum trioxide (MoO3) nanosheets as anode material for LIBs. We exploit liquid phase exfoliation of layered MoO3 crystallites to produce multilayer MoO3 nanosheets dispersed in isopropanol, which are then mixed with solution processed SWNTs in the same solvent. The addition of SWNTs to the MoO3 nanosheets provides the conductive framework for electron transport, as well as a bridge structure, which buffers the volume expansion upon lithiation/de-lithiation. We demonstrate that the hybrid SWNT-bridged MoO3 structure is beneficial for both the mechanical stability and the electrochemical characteristics of the anodes leading to a specific capacity of 865 mAh g‑1 at 100 mA g‑1 after 100 cycles, with a columbic efficiency approaching 100% and a capacity fading of 0.02% per cycle. The low-cost, non-toxic, binder-free hybrid MoO3/SWNT here developed represents a step forward for the applicability of exfoliated MoO3 in LIB anodes, delivering high energy and power densities as well as long lifetime.

  11. Performance evaluation of platinum-molybdenum carbide nanocatalysts with ultralow platinum loading on anode and cathode catalyst layers of proton exchange membrane fuel cells

    Science.gov (United States)

    Saha, Shibely; Cabrera Rodas, José Andrés; Tan, Shuai; Li, Dongmei

    2018-02-01

    An alternative catalyst platform, consisting of a phase-pure transition carbide (TMC) support and Pt nanoparticles (NPs) in the range of subnanometer to idealized disk electrode screening tests, few to none have been applied in a realistic fuel cell membrane electrode assembly (MEA). We recently reported that β-Mo2C hollow nanotubes modified with Pt NPs via atomic layer deposition (ALD) possess better activity and durability than 20% Pt/C. This paper presents systematic evaluation of the Pt/Mo2C catalysts in a MEA, investigating effects of different MEA preparation techniques, gas diffusion layers (GDL) and various Pt loadings in the ultralow range (hydrogen (H2) and oxygen (O2). Accelerated degradation tests (ADT) on Pt/Mo2C catalysts show 111% higher power density than commercial 20% Pt/C after the vigorous ADT.

  12. Structural and optical studies of GaN pn-junction with AlN buffer layer grown on Si (111) by RF plasma enhanced MBE

    Energy Technology Data Exchange (ETDEWEB)

    Yusoff, Mohd Zaki Mohd; Hassan, Zainuriah; Woei, Chin Che; Hassan, Haslan Abu; Abdullah, Mat Johar [Nano-Optoelectronics Research and Technology Laboratory School of Physics, Universiti Sains Malaysia, 11800 Penang, Malaysia and Department of Applied Sciences Universiti Teknologi MARA (UiTM) 13500 Permatang Pauh, Penang (Malaysia); Department of Applied Sciences Universiti Teknologi MARA (UiTM) 13500 Permatang Pauh, Penang (Malaysia)

    2012-06-29

    GaN pn-junction grown on silicon substrates have been the focus in a number of recent reports and further effort is still necessary to improve its crystalline quality for practical applications. GaN has the high n-type background carrier concentration resulting from native defects commonly thought to be nitrogen vacancies. In this work, we present the growth of pn-junction of GaN on Si (111) substrate using RF plasma-enhanced molecular beam epitaxy (MBE). Both of the layers show uniformity with an average thickness of 0.709 {mu}m and 0.095 {mu}m for GaN and AlN layers, respectively. The XRD spectra indicate that no sign of cubic phase of GaN are found, so it is confirmed that the sample possessed hexagonal structure. It was found that all the allowed Raman optical phonon modes of GaN, i.e. the E2 (low), E1 (high) and A1 (LO) are clearly visible.

  13. Recent advances in polymer solar cells: realization of high device performance by incorporating water/alcohol-soluble conjugated polymers as electrode buffer layer.

    Science.gov (United States)

    He, Zhicai; Wu, Hongbin; Cao, Yong

    2014-02-01

    This Progress Report highlights recent advances in polymer solar cells with special attention focused on the recent rapid-growing progress in methods that use a thin layer of alcohol/water-soluble conjugated polymers as key component to obtain optimized device performance, but also discusses novel materials and device architectures made by major prestigious institutions in this field. We anticipate that due to drastic improvements in efficiency and easy utilization, this method opens up new opportunities for PSCs from various material systems to improve towards 10% efficiency, and many novel device structures will emerge as suitable architectures for developing the ideal roll-to-roll type processing of polymer-based solar cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A mesoporous WO3−X/graphene composite as a high-performance Li-ion battery anode

    International Nuclear Information System (INIS)

    Liu, Fei; Kim, Jong Gu; Lee, Chul Wee; Im, Ji Sun

    2014-01-01

    Graphical abstract: The highly flexible and conductive graphene layer can enhance electron transfer, protect metal oxides against disintegration and aggregation and buffer the strain induced by volume expansion during cycles. The mesoporous surface layer provides an open network for Li+ diffusion. - Highlights: • Novel cocktail effects of 2D mesoporous WO 3−X /graphene for lithium ion battery. • New approach for lithium ion battery by easy and unique synthesis method. • Mechanism study with proper data for understanding a reaction on anode surface. - Abstract: A novel mesoporous WO 3−X /graphene composite was developed. This material allowed rapid electron and Li + ion diffusion when used as a Li-ion battery (LIB) anode material. Remarkably, the graphene support protected WO 3−X from changing volume during the electrochemical cycling process; this process generally induces capacity loss. The current work describes a high-performance anode material for LIB that has highly dense WO 3−X , as well as high capacity, rate capability and stability

  15. Consequences of Anode Interfacial Layer Deletion. HCl-Treated ITO in P3HT:PCBM-Based Bulk-Heterojunction Organic Photovoltaic Devices

    Science.gov (United States)

    2010-01-01

    an overall increase in light-to-power conversion efficiency (Eff) of 70% to 5.0% with an active layer composed of poly- (3-hexylthiophene) ( P3HT ) and...electrical homogenization. This suggests that an interface capable ofOhmic contact to the P3HT electron donor for loss-less charge collection might be...Device Fabrication. A clean, dry 10 mL Schlenk flask was charged with P3HT (20 mg), PCBM (20 mg), and a stir bar. The flask was cycled N2/vacuum

  16. Biodegradable neural cell culture sheet made of poly(lactic-co-glycolic acid) thin film with micropatterns of Dulbecco’s phosphate-buffered saline (‑) containing laminin layers

    Science.gov (United States)

    Nakamura, Yuki; Horiuchi, Shunpu; Nishioka, Yasushiro

    2018-02-01

    In the regenerative medicine field of nervous systems, techniques used to fabricate microstructures of neurons on flexible and biodegradable substrates have attracted attention. In this research, biodegradable and flexible neuron culture thin films that enable the selective axonal outgrowth of neurons were fabricated using poly(lactic-co-glycolic acid) (PLGA) thin films with micropatterns of Dulbecco’s phosphate-buffered saline (D-PBS) (‑) containing laminin layers. The 100-µm-thick PLGA thin films were fabricated by diluting PLGA in acetone (5% w/w) and the solution was distributed onto a poly(dimethylsiloxane) (PDMS) mold. D-PBS (‑) micropatterns containing laminin layers with widths of 10–150 µm were fabricated by micromolding in capillaries (MIMIC) and the microstencil method. Rat neurons were selectively cultured for 3 d on the laminin micropatterns; using the MIMIC method, the cells properly adhered to a pattern wider than 30 µm, while with the microstencil method, the necessary pattern width for proper adhesion was more than 50 µm.

  17. Buffer Zone Fact Sheets

    Science.gov (United States)

    New requirements for buffer zones and sign posting contribute to soil fumigant mitigation and protection for workers and bystanders. The buffer provides distance between the pesticide application site and bystanders, reducing exposure risk.

  18. Perpendicular magnetic anisotropy in Mo/Co2FeAl0.5Si0.5/MgO/Mo multilayers with optimal Mo buffer layer thickness

    Science.gov (United States)

    Saravanan, L.; Raja, M. Manivel; Prabhu, D.; Pandiyarasan, V.; Ikeda, H.; Therese, H. A.

    2018-05-01

    Perpendicular Magnetic Anisotropy (PMA) was realized in as-deposited Mo(10)/Co2FeAl0.5Si0.5(CFAS)(3)/MgO(0.5)/Mo multilayer stacks with large perpendicular magnetic anisotropy energy (Keff). PMA of this multilayer is found to be strongly dependent on the thickness of the individual CFAS (tCFAS), Mo (tMo) and MgO (tMgO) layers and annealing temperatures. The interactions at the Mo/CFAS/MgO interfaces are critical to induce PMA and are tuned by the interfacial oxidation. The major contribution to PMA is due to iron oxide at the CFAS/MgO interface. X-ray diffraction (XRD) and infrared spectroscopic (FT-IR) studies further ascertain this. However, an adequate oxidation of MgO and the formation of (0 2 4) and (0 1 8) planes of α-Fe2O3 at the optimal Mo buffer layer thickness is mainly inducing PMA in Mo/CFAS/MgO/Mo stack. Microstructural changes in the films are observed by atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) demonstrates the oxidation of CFAS/MgO interface and the formation of Fe-O bonds confirming that the real origin of PMA in Mo/CFAS/MgO is due to hybridization of Fe (3dz2) and O (2pz) orbitals and the resulted spin-orbit interaction at their interface. The half-metallic nature CFAS with Mo layer exhibiting PMA can be a potential candidate as p-MTJs electrodes for the new generation spintronic devices.

  19. Arc attachment at HID anodes: measurements and interpretation

    International Nuclear Information System (INIS)

    Redwitz, M; Dabringhausen, L; Lichtenberg, S; Langenscheidt, O; Heberlein, J; Mentel, J

    2006-01-01

    Anodes for high intensity discharge lamps made of cylindrical tungsten rods and the plasma in front of them are investigated in a special lamp filled with argon and other noble gases at pressures of 0.1-1 MPa. The arc attachment on these anodes takes place in a constricted mode. The temperature is measured pyrometrically along the electrode axis and the anode fall electrically. The electron temperature, T e , and the electron density, n e , within the anodic boundary layer are determined spectroscopically with high spatial resolution. It is found that the power input into the anode increases nearly linearly with the arc current. The proportionality constant is mainly determined by the work function of the electrode material and T e but is independent of the electrically measured anode fall and scarcely dependent on the electrode dimensions. The constriction is more pronounced in cold anodes, with maxima of T e and n e in front of the electrode surface, than on hot anodes with thermionic electron emission and vaporization of the electrode material. The distances of the T e - and n e -maxima from the anode surface are increased and T e is reduced in front of the anode with increasing anode temperature. The experimental findings may be explained by a model of the anodic boundary layer consisting of a thin sheath in front of the surface and a more extended constriction zone. The current and voltage are anti-parallel within the sheath. The power which is needed to sustain the sheath is supplied by an enhanced electrical power input into the constriction zone

  20. Layered Lepidocrocite Type Structure Isolated by Revisiting the Sol–Gel Chemistry of Anatase TiO 2 : A New Anode Material for Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jiwei [Sorbonne Universités,; Reeves, Kyle G. [Sorbonne Universités,; Porras Gutierrez, Ana-Gabriela [Sorbonne Universités,; Body, Monique [Université; Legein, Christophe [Université; Kakinuma, Katsuyoshi [Fuel; Borkiewicz, Olaf J. [X-ray; Chapman, Karena W. [X-ray; Groult, Henri [Sorbonne Universités,; Salanne, Mathieu [Sorbonne Universités,; Réseau; Dambournet, Damien [Sorbonne Universités,; Réseau

    2017-09-19

    Searches for new electrode materials for batteries must comply on financial and environmental costs to be useful in practical devices. The sol-gel chemistry has been widely used to design and implemented new concepts for the emergence of advanced materials such as hydride organic-inorganic composites. Here, we show that the simple reaction system including titanium alkoxide and water can be used to stabilize a new class of electrode materials. By investigating the crystallization path of anatase TiO2, an X-ray amorphous intermediate phase has been identified whose local structure probed by the pair distribution function, 1H solid-state NMR and DFT calculations, consists of a layered-type structure as found in the lepido-crocite. This phase presents the following general formula Ti2-xxO4-4x(OH)4x.nH2O (x ~ 0.5) where the substitution of oxide by hydroxide anions leads to the formation of titanium vacancies (•) and H2O molecules are located in interlayers. Solid-state 1H NMR has enabled to characterize three main hydroxide environments that are Ti⟂-OH, Ti22-OH and Ti3⟂-OH and layered H2O molecules. The electrochemical properties of this phase were further investigated versus lithium and is shown to be very promising with reversible capacities of around 200 mAh.g-1 and an operating voltage of 1.55 V. We further showed that the lithium intercalation proceeds via a solid-solution mechanism. 7Li solid-state NMR and DFT calculations allowed to identify lithium host sites that are located at the titanium vacancies and interlayer space with lithium being solvated by structural water molecules. The easy fabrication, the absence of lithium and easier recycling and the encouraging properties makes this class of materials very attractive for competitive electrodes for batteries. We thus demonstrate that the revisit of an “old” chemistry with

  1. Anodized dental implant surface

    Directory of Open Access Journals (Sweden)

    Sunil Kumar Mishra

    2017-01-01

    Full Text Available Purpose: Anodized implants with moderately rough surface were introduced around 2000. Whether these implants enhanced biologic effect to improve the environment for better osseointegration was unclear. The purpose of this article was to review the literature available on anodized surface in terms of their clinical success rate and bone response in patients till now. Materials and Methods: A broad electronic search of MEDLINE and PubMed databases was performed. A focus was made on peer-reviewed dental journals. Only articles related to anodized implants were included. Both animal and human studies were included. Results: The initial search of articles resulted in 581 articles on anodized implants. The initial screening of titles and abstracts resulted in 112 full-text papers; 40 animal studies, 16 studies on cell adhesion and bacterial adhesion onto anodized surfaced implants, and 47 human studies were included. Nine studies, which do not fulfill the inclusion criteria, were excluded. Conclusions: The long-term studies on anodized surface implants do favor the surface, but in most of the studies, anodized surface is compared with that of machined surface, but not with other surfaces commercially available. Anodized surface in terms of clinical success rate in cases of compromised bone and immediately extracted sockets has shown favorable success.

  2. Modeling of anodic dissolution of U Pu Zr ternary alloy in the molten LiCl KCl electrolyte

    Science.gov (United States)

    Iizuka, Masatoshi; Kinoshita, Kensuke; Koyama, Tadafumi

    2005-02-01

    The metallic fuel anode in the molten salt electrorefining step for the pyrometallurgical reprocessing was modeled based on the findings from the anodic dissolution tests using a U Pu Zr ternary alloy. This anode model simulates selective dissolution of uranium and plutonium at lower anode potential, growth of a diffusion controlling layer consisting of a mixture of the molten salt electrolyte and the remaining zirconium metal, and simultaneous dissolution of all the constituents at higher anode potential. The calculation with this model reproduced well the actual anodic behavior of the U Pu Zr ternary alloy such as two-step rapid rise in the anode potential.

  3. Solution-processed vanadium oxide as a hole collection layer on an ITO electrode for high-performance polymer solar cells.

    Science.gov (United States)

    Tan, Zhan'ao; Zhang, Wenqing; Cui, Chaohua; Ding, Yuqin; Qian, Deping; Xu, Qi; Li, Liangjie; Li, Shusheng; Li, Yongfang

    2012-11-14

    A solution-processed vanadium oxide (s-VO(x)) anode buffer layer on an indium-tin-oxide (ITO) electrode was used instead of PEDOT:PSS for improving the stability and photovoltaic performance of the polymer solar cells (PSCs). The s-VO(x) layer was prepared by spin-coating a vanadyl acetylacetonate (VO(acac)(2)) isopropyl alcohol solution on the ITO electrode and then thermal annealing at 150 °C for 10 min. The s-VO(x) oxide layer is highly transparent in the visible range and shows effective hole collection property. The photovoltaic performance of the s-VO(x) buffer layer was studied by fabricating the PSCs based on poly(3-hexylthiophene) (P3HT) as an electron donor and four soluble fullerene derivatives, [6,6]-phenyl-C(61)-butyric acid methyl ester (PC(60)BM), [6,6]-phenyl-C(71)-butyric acid methyl ester (PC(70)BM), indene-C(60) bisadduct (IC(60)BA), and indene-C(70) bisadduct (IC(70)BA), as electron acceptors. The PSCs with the s-VO(x) buffer layer show improved performance in comparison with the traditional devices with the PEDOT:PSS buffer layer on ITO, no matter which fullerene derivative was used as an acceptor. The power conversion efficiency of the PSC based on P3HT:IC(70)BA (1 : 1, w/w) with the s-VO(x) anode buffer layer reached 6.35% under the illumination of AM1.5G 100 mW cm(-2).

  4. Effect of organic-buffer-layer on electrical property and environmental reliability of Ga-doped ZnO films prepared by RF plasma assisted DC magnetron sputtering on plastic substrate

    International Nuclear Information System (INIS)

    Hinoki, Toshio; Kyuhara, Chika; Agura, Hideaki; Yazawa, Kenji; Kinoshita, Kentaro; Ohmi, Koutoku; Kishida, Satoru

    2010-01-01

    Ga-doped ZnO (GZO) transparent conductive films have been prepared by RF plasma assisted DC magnetron sputtering under a reductive atmosphere on organic-buffer-layer (OBL) coated polyethylene telephthalate (PET) substrates without intentionally heating substrates. Electrical and optical properties, crystallinity, and environmental reliability of the GZO films have been investigated. The distributional characteristic of resistivity is observed in the GZO film deposited on the OBL-coated PET substrates. The high resistivity at facing the erosion area in the source target is reduced by providing the RF plasma and H 2 gas near the substrate, resulting in a uniform distribution of the sheet resistance. It has been also found that the increase of resistivity by an accelerated aging test performed under a storage condition at 60 o C and at a relative humidity of 95% is suppressed by employing the OBL. The OBL suppresses the formation of cracks, which are induced by the aging test. These facts are thought to contribute to a high environmental reliability of GZO films on PET substrates. Values of resistivity, Hall mobility and carrier concentration are obtained: 5.0-20 x 10 -3 Ω cm, 4.0 cm 2 /Vs, and 3.8 x 10 20 cm -3 , respectively. An average transmittance of the GZO film including OBL and PET substrate is 78% in a visible region. The OBL enables to realize the practical use of GZO films on PET sheets.

  5. Epitaxial growth and dielectric properties of Bi sub 2 VO sub 5 sub . sub 5 thin films on TiN/Si substrates with SrTiO sub 3 buffer layers

    CERN Document Server

    Lee, H Y; Choi, B C; Jeong, J H; Joseph, M; Tabata, H; Kawai, T

    2000-01-01

    Bi sub 2 VO sub 5 sub . sub 5 (BVO) thin films were epitaxially grown on SrTiO sub 3 /TiN/Si substrates by using pulsed laser ablation. A TiN thin film was prepared at 700 .deg. C as a bottom electrode. The TiN film exhibited a high alpha axis orientation and a very smooth morphology. Before the preparation of the BVO thin film, a crystallized SrTiO sub 3 thin film was deposited as a buffer layer on TiN/Si. The BVO thin film grown at a substrate temperature at 700 .deg. C and an oxygen pressure of 50 mTorr was found to be epitaxial along the c-axis. Also, BVO films were observed to have flat surfaces and the step-flow modes. The dielectric constant of the BVO film on STO/TiN/Si was constant at about 8 approx 4 in the applied frequency range between 10 sup 2 and 10 sup 6 Hz.

  6. Redox Buffer Strength

    Science.gov (United States)

    de Levie, Robert

    1999-04-01

    The proper functioning of enzymes in bodily fluids requires that the pH be maintained within rather narrow limits. The first line of defense against large pH fluctuations in such fluids is the passive control provided by the presence of pH buffers. The ability of pH buffers to stabilize the pH is indicated by the buffer value b introduced in 1922 by van Slyke. It is equally important for many enzymes that the redox potential is kept within a narrow range. In that case, stability of the potential is most readily achieved with a redox buffer. In this communication we define the redox buffer strength by analogy with acid-base buffer strength.

  7. Organellar Calcium Buffers

    Science.gov (United States)

    Prins, Daniel; Michalak, Marek

    2011-01-01

    Ca2+ is an important intracellular messenger affecting many diverse processes. In eukaryotic cells, Ca2+ storage is achieved within specific intracellular organelles, especially the endoplasmic/sarcoplasmic reticulum, in which Ca2+ is buffered by specific proteins known as Ca2+ buffers. Ca2+ buffers are a diverse group of proteins, varying in their affinities and capacities for Ca2+, but they typically also carry out other functions within the cell. The wide range of organelles containing Ca2+ and the evidence supporting cross-talk between these organelles suggest the existence of a dynamic network of organellar Ca2+ signaling, mediated by a variety of organellar Ca2+ buffers. PMID:21421925

  8. Anodic oxidation of Ta/Fe alloys

    International Nuclear Information System (INIS)

    Mato, S.; Alcala, G.; Thompson, G.E.; Skeldon, P.; Shimizu, K.; Habazaki, H.; Quance, T.; Graham, M.J.; Masheder, D.

    2003-01-01

    The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V -1 . Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface

  9. Effect of a CGO buffer layer on the performance of (La0.6Sr0.40.995Co0.2Fe0.8O3-δ cathode in YSZ-Based SOFC

    Directory of Open Access Journals (Sweden)

    Ruiz-Morales, J. C.

    2010-02-01

    Full Text Available The electrochemical properties of (La0.6Sr0.40.995Co0.2Fe0.8O3-s (LSCF and LSCF-gadolinium-doped ceria (CGO composite electrodes towards oxygen reduction were studied by impedance spectroscopy in a symmetric cell configuration using yttriastabilised zirconia (YSZ as electrolyte and a CGO buffer layer between the electrode and the electrolyte materials. The best polarisation resistance values were obtained for a LSCF-CGO (60/40, wt.% composite with values ranging between 0.07 and 0.4 Ωcm2 in the temperature range of 650-775ºC. The effect of the CGO buffer on the polarisation resistance of the LSCF electrode and the series resistance of the symmetrical LSCF/YSZ cell was also investigated. In addition, X-ray diffraction analysis was carried out to study the chemical compatibility between LSCF, YSZ and CGO materials.Las propiedades electroquímicas de los electrodos (La0.6Sr0.40.995Co0.2Fe0.8O3-δ (LSCF y composites de LSCF con ceria dopada con gadolinio (CGO, respecto la reacción de reducción del oxígeno, fueron estudiadas mediante espectroscopía de impedancia usando una configuración de celda simétrica, con circonia estabilizada con itria (YSZ como electrolito y CGO como capa de protección entre el material de electrodo y electrolito. Los mejores valores de resistencia de polarización fueron obtenidos para el composite LSCF-CGO (60/40, % en peso con valores comprendidos entre 0,07 y 0,4 Ωcm2 para el rango de temperaturas de 650-775ºC. El efecto de la capa intermedia de CGO sobre la resistencia de polarización del electrodo LSCF y la resistencia en serie de la celda simétrica LSCF/YSZ fue también investigado. La compatibilidad química de LSCF, YSZ y CGO se ha estudiado mediante difracción de rayos X.

  10. Rapid screening buffer layers in photovoltaics

    Science.gov (United States)

    List, III, Frederick Alyious; Tuncer, Enis

    2014-09-09

    An apparatus and method of testing electrical impedance of a multiplicity of regions of a photovoltaic surface includes providing a multi-tipped impedance sensor with a multiplicity of spaced apart impedance probes separated by an insulating material, wherein each impedance probe includes a first end adapted for contact with a photovoltaic surface and a second end in operable communication with an impedance measuring device. The multi-tipped impedance sensor is used to contact the photovoltaic surface and electrical impedance of the photovoltaic material is measured between individual first ends of the probes to characterize the quality of the photovoltaic surface.

  11. Organic photovoltaic device with interfacial layer and method of fabricating same

    Science.gov (United States)

    Marks, Tobin J.; Hains, Alexander W.

    2013-03-19

    An organic photovoltaic device and method of forming same. In one embodiment, the organic photovoltaic device has an anode, a cathode, an active layer disposed between the anode and the cathode; and an interfacial layer disposed between the anode and the active layer, the interfacial layer comprising 5,5'-bis[(p-trichlorosilylpropylphenyl)phenylamino]-2,2'-bithiophene (PABTSi.sub.2).

  12. Anode Support Creep

    DEFF Research Database (Denmark)

    2015-01-01

    Initial reduction temperature of an SOC is kept higher than the highest intended operation temperature of the SOC to keep the electrolyte under compression by the Anode Support at all temperatures equal to and below the maximum intended operation temperature.......Initial reduction temperature of an SOC is kept higher than the highest intended operation temperature of the SOC to keep the electrolyte under compression by the Anode Support at all temperatures equal to and below the maximum intended operation temperature....

  13. Liquid Silicon Pouch Anode

    Science.gov (United States)

    2017-09-06

    collector 18 can be made from nickel; however, other high conductivity metals and alloys can be used for this such as gold, silver , platinum, alloys of...The conductive particles can be carbon such as carbon black or graphite. These particles can also be metals such as copper, nickel, silver , gold...anode cycling characteristics, higher battery capacity, and longer cycle life. [0005] Rechargeable batteries with lithium metal anodes have been

  14. Aspects of the SrO-CuO-TiO2 Ternary System Related to the Deposition of SrTiO3 and Copper-Doped SrTiO3 Thin-Film Buffer Layers

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, Alicia [Univ. of New Mexico, Albuquerque, NM (United States)

    2004-12-20

    YBa2Cu3O27-δ (YBCO) coated conductors are promising materials for large-scale superconductivity applications. One version of a YBCO coated conductor is based on ion beam assisted deposition (IBAD) of magnesium oxide (MgO) onto polycrystalline metal substrates. SrTiO3 (STO) is often deposited by physical vapor deposition (PVD) methods as a buffer layer between the YBCO and IBAD MgO due to its chemical stability and lattice mismatch of only ~1.5% with YBCO. In this work, some aspects of the stability of STO with respect to copper (Cu) and chemical solution deposition of STO on IBAD MgO templates were examined. Solubility limits of Cu in STO were established by processing Cu-doped STO powders by conventional bulk preparation techniques. The maximum solubility of Cu in STO was ~1% as determined by transmission electron microscopy (TEM) and Rietveld refinements of x-ray diffraction (XRD) data. XRD analysis, performed in collaboration with NIST, on powder compositions on the STO/SrCuO2 tie line did not identify any ternary phases. SrCu0.10T0.90Oy buffer layers were prepared by pulsed laser deposition (PLD) and CSD on IBAD MgO flexible metallic textured tapes. TEM analysis of a ~100 nm thick SrCu0.10Ti0.90Oy buffer layer deposited by PLD showed a smooth Cu-doped STO/MgO interface. A ~600 nm thick YBCO film, deposited onto the SrCu0.10Ti0.90Oy buffer by PLD, exhibited a Tc of 87 K and critical current density (Jc) of ~1 MA/cm2. STO and Cu-doped STO thin films by CSD were ~30 nm thick. The in plane alignment (FWHM) after deposition of the STO improved by ~1° while it degraded by ~2° with the SrCu0.05TiOy buffer. YBCO was deposited by PLD on the STO and SrCu0.05TiOy buffers. The in plane alignment (FWHM) of the YBCO with the STO buffer layer

  15. Growth and Characterization of (211)B Cadmium Telluride Buffer Layer Grown by Metal-organic Vapor Phase Epitaxy on Nanopatterned Silicon for Mercury Cadmium Telluride Based Infrared Detector Applications

    Science.gov (United States)

    Shintri, Shashidhar S.

    Mercury cadmium telluride (MCT or Hg1-xCdxTe) grown by molecular beam epitaxy (MBE) is presently the material of choice for fabricating infrared (IR) detectors used in night vision based military applications. The focus of MCT epitaxy has gradually shifted since the last decade to using Si as the starting substrate since it offers several advantages. But the ˜19 % lattice mismatch between MCT and Si generates lots of crystal defects some of which degrade the performance of MCT devices. Hence thick CdTe films are used as buffer layers on Si to accommodate the defects. However, growth of high quality single crystal CdTe on Si is challenging and to date, the best MBE CdTe/Si reportedly has defects in the mid-105 cm -2 range. There is a critical need to reduce the defect levels by at least another order of magnitude, which is the main motivation behind the present work. The use of alternate growth technique called metal-organic vapor phase epitaxy (MOVPE) offers some advantages over MBE and in this work MOVPE has been employed to grow the various epitaxial films. In the first part of this work, conditions for obtaining high quality (211)B CdTe epitaxy on (211)Si were achieved, which also involved studying the effect of having additional intermediate buffer layers such as Ge and ZnTe and incorporation of in-situ thermal cyclic annealing (TCA) to reduce the dislocation density. A critical problem of Si cross-contamination due to 'memory effect' of different reactant species was minimized by introducing tertiarybutylArsine (TBAs) which resulted in As-passivation of (211)Si. The best 8-10 µm thick CdTe films on blanket (non-patterned) Si had dislocations around 3×105 cm-2, which are the best reported by MOVPE till date and comparable to the highest quality films available by MBE. In the second part of the work, nanopatterned (211)Si was used to study the effect of patterning on the crystal quality of epitaxial CdTe. In one such study, patterning of ˜20 nm holes in SiO2

  16. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application.

    Science.gov (United States)

    Slaughter, Gymama; Stevens, Brian

    2015-11-16

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 mW/ cm² in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm², respectively.

  17. Quantitative relationship between nanotube length and anodizing current during constant current anodization

    International Nuclear Information System (INIS)

    Zhang, Yulian; Cheng, Weijie; Du, Fei; Zhang, Shaoyu; Ma, Weihua; Li, Dongdong; Song, Ye; Zhu, Xufei

    2015-01-01

    Highlights: • Ti anodization was performed by constant current rather than constant voltage. • The nanotube length was controlled by ionic current rather than dissolution current. • Electronic current can be estimated by the nanotube length and the anodizing current. • Dissolution reaction hardly contributes electric current across the barrier layer. - Abstract: The growth kinetics of anodic TiO 2 nanotubes (ATNTs) still remains unclear. ATNTs are generally fabricated under potentiostatic conditions rather than galvanostatic ones. The quantitative relationship between nanotube length and anodizing current (J total ) is difficult to determine, because the variable J total includes ionic current (J ion ) (also called oxide growth current J grow =J ion ) and electronic current (J e ), which cannot be separated from each other. One successful approach to achieve this objective is to use constant current anodization rather than constant voltage anodization, that is, through quantitative comparison between the nanotube length and the known J total during constant current anodization, we can estimate the relative magnitudes of J grow and J e . The nanotubes with lengths of 1.24, 2.23, 3.51 and 4.70 μm, were formed under constant currents (J total ) of 15, 20, 25 and 30 mA, respectively. The relationship between nanotube length (y) and anodizing current (x =J total =J grow +J e ) can be expressed by a fitting equation: y=0.23(x-10.13), from which J grow (J grow = x -10.13) and J e (∼10.13 mA) could be inferred under the present conditions. Meanwhile, the same conclusion could also be deduced from the oxide volume data. These results indicate that the nanotube growth is attributed to the oxide growth current rather than the dissolution current.

  18. How effective are slurry storage, cover or catch crops, woodland creation, controlled trafficking or break-up of compacted layers, and buffer strips as on-farm mitigation measures for delivering an improved water environment?

    Directory of Open Access Journals (Sweden)

    Randall Nicola P

    2012-10-01

    Full Text Available Abstract Background Agriculture has intensified over the last 50 years resulting in increased usage of fertilizers and agrochemicals, changes in cropping practices, land drainage and increased stocking rates. In Europe, this has resulted in declines in the quality of soils and waters due to increased run off and water pollution. Fifty percent of nitrates in European rivers are derived from agricultural sources in the UK this value is as high as 70%, where agriculture also contributes to approximately 28% of phosphates and 76% of sediments recorded in rivers. Catchments dominated by agricultural land use have increased levels of pesticides and bacterial pathogens. European member states have a policy commitment to tackle water pollution through the Water Framework Directive. An analysis of the effectiveness of water pollution mitigation measures should enable decision makers and delivery agencies to better facilitate catchment planning. The aim of this systematic review is to assess the effectiveness of slurry storage, cover/catch crops, woodland creation, controlled trafficking/break-up of compacted layers and buffer strips, as on farm mitigation measures, for delivering an improved water environment. Methods The systematic review will consist of a searchable systematic map database for all the named interventions. Where possible, quantitative analysis will be used to assess the effectiveness of interventions. Electronic databases, the internet, and organisational websites will be searched, and stakeholders will be contacted for studies that investigate the impact of the on-farm mitigation measures on water quality. All studies found will be assessed for suitability for inclusion in the next stage. Inclusion criteria will be based on subject, intervention, comparator and outcome. The details of included studies will be incorporated into the systematic map database, and studies scored for effectiveness of intervention and study design. Where

  19. Improvement in direct methanol fuel cell performance by treating the anode at high anodic potential

    Science.gov (United States)

    Joghee, Prabhuram; Pylypenko, Svitlana; Wood, Kevin; Corpuz, April; Bender, Guido; Dinh, Huyen N.; O'Hayre, Ryan

    2014-01-01

    This work investigates the effect of a high anodic potential treatment protocol on the performance of a direct methanol fuel cell (DMFC). DMFC membrane electrode assemblies (MEAs) with PtRu/C (Hi-spec 5000) anode catalyst are subjected to anodic treatment (AT) at 0.8 V vs. DHE using potentiostatic method. Despite causing a slight decrease in the electrochemical surface area (ECSA) of the anode, associated with ruthenium dissolution, AT results in significant improvement in DMFC performance in the ohmic and mass transfer regions and increases the maximum power density by ∼15%. Furthermore, AT improves the long-term DMFC stability by reducing the degradation of the anode catalyst. From XPS investigation, it is hypothesized that the improved performance of AT-treated MEAs is related to an improved interface between the catalyst and Nafion ionomer. Among potential explanations, this improvement may be caused by incorporation of the ionomer within the secondary pores of PtRu/C agglomerates, which generates a percolating network of ionomer between PtRu/C agglomerates in the catalyst layer. Furthermore, the decreased concentration of hydrophobic CF2 groups may help to enhance the hydrophilicity of the catalyst layer, thereby increasing the accessibility of methanol and resulting in better performance in the high current density region.

  20. Fabrication of 5 cm long epitaxial Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9-x} single buffer layer on textured Ni-5%W substrate for YBCO coated conductors via dip-coating PACSD method

    Energy Technology Data Exchange (ETDEWEB)

    Lei, M.; Wang, W.T.; Pu, M.H.; Yang, X.S.; He, L.J. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [Science and Engineering, University of New South Wales, Sydney 2052, New South Wales (Australia); Zhao, Y., E-mail: yzhao@home.swjtu.edu.cn [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)] [Science and Engineering, University of New South Wales, Sydney 2052, New South Wales (Australia)

    2011-11-15

    Epitaxial Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9-x} single buffer layer for YBCO coated conductors was deposited via fluorine-free dip-coating CSD. Flat, dense and crack-free SCO films with sharp (2 0 0) c-axis texture were obtained by carefully controlling the processing. YBCO thin films with a homogeneous surface microstructure were deposited on the SCO-buffered NiW substrate via CSD approach. Five centimeters long epitaxial Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9-x} (SCO) single buffer layer for YBCO coated conductors was deposited via dip-coating polymer-assisted chemical solution deposition (PACSD) approach on bi-axially textured Ni-5%W (2 0 0) alloy substrate. The film formation and texture evolution were investigated using X-ray diffraction and scanning electron microscopy. Flat, dense and crack-free SCO films with sharp (2 0 0) c-axis texture were obtained by way of carefully controlling the concentration of precursor solution, withdrawing speed, annealing temperature and dwelling time. On consideration of both microstructure and texture, epitaxial SCO single buffer layers were fabricated using precursor solution of 0.3 M cationic concentration, the withdrawing speed of 10 mm/min and heat treatment at 1100 deg. C in Ar-5%H{sub 2} mixture gas for 0.5 h. Epitaxial YBCO thin films with a homogeneous surface microstructure were deposited on the SCO-buffered NiW substrate via dip-coating PACSD approach. The PACSD approach was a promising way to fabricate long and low-cost YBCO coated conductors.

  1. FRICTION BUFFER STOP DESIGN

    Directory of Open Access Journals (Sweden)

    Petr Guziur

    2017-08-01

    Full Text Available Friction buffer stops are the favoured construction of buffer stop, mainly due to its high resistance and variety of layout. Last but not least is its manner of deceleration induced upon impact and during the braking what makes it smart solution in railway transport safety. The general approach of designing buffer stops is via usage of the kinetic energy and its conversion into work. Paper describes input parameters such as train velocity or buffer stop vicinity which is expressed by the safety coefficient implanted within the calculation. Furthermore, the paper shows the principle of calculation the friction buffer stop work, or to be more precise, the work of its braking jaws and optionally the work of additional braking jaws located behind the buffer stop. Last section of the paper is focused on the examples of designing friction buffer stops, points out the main complications and shows the charts of relation amongst braking distance, kinetic energy and braking force and the charts of relation between deceleration rate and braking distance.

  2. The stochastic nuclide transport model for buffer/backfill materials

    International Nuclear Information System (INIS)

    Ma Liping; Han Yongguo

    2014-01-01

    Currently, study on nuclide migration law in geological disposal repository of high level waste is assumed buffer/backfill layer to be continuous medium, utilized the continuity equation, equation of state, the equations of motion, etc, formed a set of theory and method to estimate nuclide concentration distribution in buffer/backfill layer, and provided an important basis for nuclide migration rules of repository. However, it is necessary to study the buffer/backfill layer microstructure and subtly describe the pore structure and fracture system of the buffer/backfill layer, and reflect the changes in connectivity and in different directions of the buffer/backfill layer. Through using random field theory, the nuclide transport for the buffer/backfill layer in geological disposal repository of nuclear waste is described in the paper. This paper mainly includes that, t represents the time, ξ t ⊂ Z d = d represents the integer lattice, Z represents collectivity integers, d = l, 2, 3, for instance, d = 2, Z d = {(m, n) : m, n ∈ Z} the state point of ξ t is typically considered to be occupied by the nuclide concentration values of the buffer/backfill layer, ξ t also represents random set in the diagram of two dimensional integer lattice, namely, t ∈ [0, T], {ξ t ,0 ≤ t ≤ ⊂ T} Consequently, according to the stochastic process obtained above, the changes of the nuclide concentration values of the buffer/backfill layer or the buffer/backfill laboratory materials in the repository with the time can be known. (authors)

  3. Fuel cell anode configuration for CO tolerance

    Science.gov (United States)

    Uribe, Francisco A.; Zawodzinski, Thomas A.

    2004-11-16

    A polymer electrolyte fuel cell (PEFC) is designed to operate on a reformate fuel stream containing oxygen and diluted hydrogen fuel with CO impurities. A polymer electrolyte membrane has an electrocatalytic surface formed from an electrocatalyst mixed with the polymer and bonded on an anode side of the membrane. An anode backing is formed of a porous electrically conductive material and has a first surface abutting the electrocatalytic surface and a second surface facing away from the membrane. The second surface has an oxidation catalyst layer effective to catalyze the oxidation of CO by oxygen present in the fuel stream where at least the layer of oxidation catalyst is formed of a non-precious metal oxidation catalyst selected from the group consisting of Cu, Fe, Co, Tb, W, Mo, Sn, and oxides thereof, and other metals having at least two low oxidation states.

  4. Development of all chemical solution derived Ce0.9La0.1O2 − y/Gd2Zr2O7 buffer layer stack for coated conductors: influence of the post-annealing process on surface crystallinity

    DEFF Research Database (Denmark)

    Yue, Zhao; Li, Xiaofen; Khoryushin, Alexey

    2012-01-01

    Preparation and characterization of a biaxially textured Gd2Zr2O7 and Ce0.9La0.1O2 − y (CLO, cap)/Gd2Zr2O7 (GZO, barrier) buffer layer stack by the metal–organic deposition route are reported. YBa2Cu3O7 − d (YBCO) superconductor films were deposited by the pulsed-laser deposition (PLD) technique ...

  5. Manufacturing of anode supported SOFCs: Processing parameters and their influence

    DEFF Research Database (Denmark)

    Ramousse, Severine; Menon, Mohan; Brodersen, Karen

    2007-01-01

    The establishment of low cost, highly reliable and reproducible manufacturing processes has been focused for commercialization of SOFC technology. A major challenge in the production chain is the manufacture of anode-supported planar SOFC's single cells in which each layer in a layered structure...

  6. Lithium batteries, anodes, and methods of anode fabrication

    KAUST Repository

    Li, Lain-Jong

    2016-12-29

    Prelithiation of a battery anode carried out using controlled lithium metal vapor deposition. Lithium metal can be avoided in the final battery. This prelithiated electrode is used as potential anode for Li- ion or high energy Li-S battery. The prelithiation of lithium metal onto or into the anode reduces hazardous risk, is cost effective, and improves the overall capacity. The battery containing such an anode exhibits remarkably high specific capacity and a long cycle life with excellent reversibility.

  7. Microstructure and optical appearance of anodized friction stir processed Al - Metal oxide surface composites

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Jensen, Flemming; Bordo, Kirill

    2014-01-01

    Multiple-pass friction stir processing (FSP) was employed to impregnate Ti, Y and Ce oxide powders into the surface of an Aluminium alloy. The FSP processed surface composite was subsequently anodized with an aim to develop optical effects in the anodized layer owing to the presence of incorporated...... oxide particles which will influence the scattering of light. This paper presents the investigations on relation between microstructure of the FSP zone and optical appearance of the anodized layer due to incorporation of metal oxide particles and modification of the oxide particles due to the anodizing...

  8. A buffer diverter system

    Science.gov (United States)

    Foster, J. C., Jr.

    1985-07-01

    The prevention of sympathetic detonations between donor and acceptor bombs, which are stored lying horizontally lying parallel to each other, is accomplished using a buffer diverter system. One example of a buffer diverter system is a pair of molded concrete bases, each supporting a horizontal bomb and conforming to the shape of its respective bomb up to its horizontal centerline. In the first example, the entire space between the two molded concrete bases and bombs is filled in with a buffer which has sufficient width to attenuate the shock of detonation down pressure levels below a pressure threshold needed to induce an acceptor bomb to sympathetically detonate. In another example of a buffer diverter system, the buffer is replaced with a diverter. The diverter is an I-beam which abuts each bomb at its horizontal centerline and runs the length of the two bombs. The I-beam has the same width as the buffer, but its surface area presented to each bomb is nearly the minimum required to deflect fragments from the silhouette of the acceptor bomb.

  9. Buffer architecture for biaxially textured structures and method of fabricating same

    Science.gov (United States)

    Norton, David P.; Park, Chan; Goyal, Amit

    2004-04-06

    The invention relates to an article with an improved buffer layer architecture comprising a substrate having a metal surface, and an epitaxial buffer layer on the surface of the substrate. The epitaxial buffer layer comprises at least one of the group consisting of ZrO.sub.2, HfO.sub.2, and compounds having at least one of Ca and a rare earth element stabilizing cubic phases of ZrO.sub.2 and/or HfO.sub.2. The article can also include a superconducting layer deposited on the epitaxial buffer layer. The article can also include an epitaxial capping layer between the epitaxial buffer layer and the superconducting layer. A method for preparing an epitaxial article comprises providing a substrate with a metal surface, depositing on the metal surface an epitaxial buffer layer comprising at least one material selected from the group consisting of ZrO.sub.2, HfO.sub.2, and compounds having at least one of Ca and a rare earth element stabilizing cubic phases of at least one of ZrO.sub.2 and HfO.sub.2. The epitaxial layer depositing step occurs in a vacuum with a background pressure of no more than 1.times.10.sup.-5 Torr. The method can further comprise depositing a superconducting layer on the epitaxial layer, and depositing an epitaxial capping layer between the epitaxial buffer layer and the superconducting layer.

  10. Improved performance of organic light-emitting diode with vanadium pentoxide layer on the FTO surface

    Science.gov (United States)

    Saikia, D.; Sarma, R.

    2017-06-01

    Vanadium pentoxide layer deposited on the fluorine-doped tin oxide (FTO) anode by vacuum deposition has been investigated in organic light-emitting diode (OLED). With 12 nm optimal thickness of V2O5, the luminance efficiency is increased by 1.66 times compared to the single FTO-based OLED. The improvement of current efficiency implies that there is a better charge injection and better controlling of hole current. To investigate the performance of OLED by the buffer layer, V2O5 films of different thicknesses were deposited on the FTO anode and their J- V and L- V characteristics were studied. Further analysis was carried out by measuring sheet resistance, optical transmittance and surface morphology with the FE-SEM images. This result indicates that the V2O5 (12 nm) buffer layer is a good choice for increasing the efficiency of FTO-based OLED devices within the tunnelling region. Here the maximum value of current efficiency is found to be 2.83 cd / A.

  11. Inert Anode Report

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1999-07-01

    This ASME report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issues associated with these technologies from a technical, environmental, and economic viewpoint.

  12. Anodes for alkaline electrolysis

    Science.gov (United States)

    Soloveichik, Grigorii Lev [Latham, NY

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  13. Movable anode x-ray source with enhanced anode cooling

    Science.gov (United States)

    Bird, C.R.; Rockett, P.D.

    1987-08-04

    An x-ray source is disclosed having a cathode and a disc-shaped anode with a peripheral surface at constant radius from the anode axis opposed to the cathode. The anode has stub axle sections rotatably carried in heat conducting bearing plates which are mounted by thermoelectric coolers to bellows which normally bias the bearing plates to a retracted position spaced from opposing anode side faces. The bellows cooperate with the x-ray source mounting structure for forming closed passages for heat transport fluid. Flow of such fluid under pressure expands the bellows and brings the bearing plates into heat conducting contact with the anode side faces. A worm gear is mounted on a shaft and engages serrations in the anode periphery for rotating the anode when flow of coolant is terminated between x-ray emission events. 5 figs.

  14. Buffer design 2012

    International Nuclear Information System (INIS)

    Juvankoski, M.

    2013-08-01

    Posiva's spent nuclear fuel disposal is based on the KBS-3V concept and on the characteristics of the Olkiluoto site. In this concept single canisters containing spent nuclear fuel surrounded by a bentonite buffer are emplaced in individual vertical boreholes drilled in the floor of deposition tunnels in bedrock at about 420 m depth below ground level. Disk type bentonite blocks are installed at the bottom of the hole and on the top of the disposal canister. Ring type bentonite blocks surround the canisters. This report describes the detailed design of the buffer for a KBS-3V repository. The report presents the design basis, the reference design, and summarises the performance analyses carried out for the design. This report addresses aspects concerning the manufacture, quality control, mechanical strength, chemical resistance, thermal dimensioning, handling of buffer components and material ageing phenomena including the effect of radiation. Interaction of buffer and other engineered barriers are included in the study. The long-term evolution of the repository and its effective drivers are considered if they have an impact on the buffer performance but operational safety aspects are also included because they may affect long-term safety. (orig.)

  15. Theory and simulation of anode spots in low pressure plasmas

    Science.gov (United States)

    Scheiner, Brett; Barnat, Edward V.; Baalrud, Scott D.; Hopkins, Matthew M.; Yee, Benjamin T.

    2017-11-01

    When electrodes are biased above the plasma potential, electrons accelerated through the associated electron sheath can dramatically increase the ionization rate of neutrals near the electrode surface. It has previously been observed that if the ionization rate is great enough, a double layer separates a luminous high-potential plasma attached to the electrode surface (called an anode spot or fireball) from the bulk plasma. Here, results of the first 2D particle-in-cell simulations of anode spot formation are presented along with a theoretical model describing the formation process. It is found that ionization leads to the build-up of an ion-rich layer adjacent to the electrode, forming a narrow potential well near the electrode surface that traps electrons born from ionization. It is shown that anode spot onset occurs when a quasineutral region is established in the potential well and the density in this region becomes large enough to violate the steady-state Langmuir condition, which is a balance between electron and ion fluxes across the double layer. A model for steady-state properties of the anode spot is also presented, which predicts values for the anode spot size, double layer potential drop, and form of the sheath at the electrode by considering particle, power, and current balance. These predictions are found to be consistent with the presented simulation and previous experiments.

  16. Molecular beam deposition and polymerization of parylene-N ultrathin films: Effective buffers in organic light emitting diodes

    International Nuclear Information System (INIS)

    Hu, Y.M.; Li, R.H.; He, Y.; Zhang, X.Q.; Li, M.Q.; Zhu, Y.; Yi, J.H.; Fu, R.Ch.

    2014-01-01

    Highlights: • Parylene-N (PPXN) films prepared by using a home-made Knudsen Cell were identified and characterized. • 1 nm PPXN thin films were inserted at different locations in the hole transport layers of organic light emitting diodes. • For an optimized PPXN inserted organic light emitting diodes, current efficiency improvement of 11% was achieved. • The device current efficiency improvement and the current density variation under operation were discussed. - Abstract: Ultrathin Parylene-N (PPXN) films were prepared by using a home-made Knudsen Cell (KC). The PPXN films were identified by infrared (IR) spectra. The morphology and insulativity of PPXN films were measured by atomic force microscope (AFM) and current density versus voltage (j–V) characteristics. Well controlled 1-nm-thick PPXN thin films were inserted at different locations in the N′-bis(naphthalene-1-yl)-N, N′-bis(phenyl) benzidine (NPB) layers of organic light emitting diodes (OLEDs) with the structure of ITO/NPB/tris (8-hydroxyquinolato) aluminum (Alq 3 )/LiF/Al. For an optimized PPXN inserted structure, curr