AgSbSe2 and AgSb(S,Se)2 thin films for photovoltaic applications

International Nuclear Information System (INIS)

Garza, J.G.; Shaji, S.; Rodriguez, A.C.; Das Roy, T.K.; Krishnan, B.

2011-01-01

Silver antimony selenide (AgSbSe 2 ) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb 2 S 3 ), silver selenide (Ag 2 Se), selenium (Se) and silver (Ag). Sb 2 S 3 thin film was prepared from a chemical bath containing SbCl 3 and Na 2 S 2 O 3 , Ag 2 Se from a solution containing AgNO 3 and Na 2 SeSO 3 and Se thin films from an acidified solution of Na 2 SeSO 3 , at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10 -3 Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe 2 or AgSb(S,Se) 2 depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe 2 /Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V oc = 435 mV and J sc = 0.08 mA/cm 2 under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe 2 as an absorber material by a non-toxic selenization process is achieved.

Amorphous Si layers co-doped with B and Mn: Thin film growth and steering of magnetic properties

International Nuclear Information System (INIS)

Drera, G.; Mozzati, M.C.; Colombi, P.; Salvinelli, G.; Pagliara, S.; Visentin, D.; Sangaletti, L.

2015-01-01

Amorphous silicon thin films co-doped with manganese (5% at.) and boron (1.8% at.) have been prepared by RF sputtering on Al 2 O 3 substrates held at room temperature (RT). The films, with an average thickness of about 0.9 μm, were carefully characterized by micro-Raman and X-ray photoemission spectroscopies. A ferromagnetic (FM) behavior up to RT was observed. In order to discuss and possibly rule out extrinsic effects usually related to segregations of ferromagnetic impurities in the samples, magnetization measurements were carried out on the Al 2 O 3 substrates, as well as on Si:B and Si:Mn films grown with the same RF sputtering system. Only the Si:B:Mn films displayed a FM behavior up to RT. Since amorphous films doped with Mn alone did not display any signature of FM ordering, boron co-doping results to be crucial for the onset of the FM behavior. The conductivity of the samples is not affected by boron doping that, therefore, does not appear to significantly contribute to a possible carrier-mediated FM interaction between Mn ions by supplying extra charges to the system. On this basis, the capability of B to hinder the quenching of the Mn 3d magnetic moments has also to be regarded as a possible role of this co-dopant in the observed magnetization. - Highlights: • We successfully deposited amorphous silicon thin films co-doped with Mn and B. • Structural, electronic, and magnetic properties have been carefully characterized. • A ferromagnetic behavior up to room temperature was detected. • The extrinsic origin of magnetism is excluded. • Boron can play a relevant role to avoid quenching of magnetic moment in Mn ions

Amorphous Si layers co-doped with B and Mn: Thin film growth and steering of magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Drera, G. [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy); Mozzati, M.C. [CNISM, Dipartimento di Fisica, Università di Pavia, Via Bassi 6, 27100 Pavia (Italy); Colombi, P. [CSMT Gestione s.c.a.r.l, Via Branze 45, 25123 Brescia (Italy); Salvinelli, G.; Pagliara, S.; Visentin, D. [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy); Sangaletti, L., E-mail: sangalet@dmf.unicatt.it [I-LAMP, Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Via dei Musei 41, 25121 Brescia (Italy)

2015-09-01

Amorphous silicon thin films co-doped with manganese (5% at.) and boron (1.8% at.) have been prepared by RF sputtering on Al{sub 2}O{sub 3} substrates held at room temperature (RT). The films, with an average thickness of about 0.9 μm, were carefully characterized by micro-Raman and X-ray photoemission spectroscopies. A ferromagnetic (FM) behavior up to RT was observed. In order to discuss and possibly rule out extrinsic effects usually related to segregations of ferromagnetic impurities in the samples, magnetization measurements were carried out on the Al{sub 2}O{sub 3} substrates, as well as on Si:B and Si:Mn films grown with the same RF sputtering system. Only the Si:B:Mn films displayed a FM behavior up to RT. Since amorphous films doped with Mn alone did not display any signature of FM ordering, boron co-doping results to be crucial for the onset of the FM behavior. The conductivity of the samples is not affected by boron doping that, therefore, does not appear to significantly contribute to a possible carrier-mediated FM interaction between Mn ions by supplying extra charges to the system. On this basis, the capability of B to hinder the quenching of the Mn 3d magnetic moments has also to be regarded as a possible role of this co-dopant in the observed magnetization. - Highlights: • We successfully deposited amorphous silicon thin films co-doped with Mn and B. • Structural, electronic, and magnetic properties have been carefully characterized. • A ferromagnetic behavior up to room temperature was detected. • The extrinsic origin of magnetism is excluded. • Boron can play a relevant role to avoid quenching of magnetic moment in Mn ions.

Growth and in-plane magnetic anisotropy of inverse spinel Co{sub 2}MnO{sub 4} thin films

Energy Technology Data Exchange (ETDEWEB)

Koo, Taeyeong; Kim, Jaeyeong [Pohang University of Science and Technology, Pohang (Korea, Republic of); Song, Jonghyun [Chungnam National University, Daejeon (Korea, Republic of)

2014-11-15

Epitaxial Co{sub 2}MnO{sub 4} thin films were grown on Nb(0.1wt.)-doped SrTiO{sub 3} single-crystal substrates with (100) and (110) crystal orientations by using pulsed laser deposition. Their crystal structures and magnetic properties were investigated. Both samples exhibited ferrimagnetic transitions with enhanced transition temperatures. Isotropic M-H loops were observed on the in-plane surface of Co{sub 2}MnO{sub 4}(00l) grown on Nb(0.1wt)-doped SrTiO{sub 3}(100). Strong magnetic anisotropy was observed on the in-plane surface for Co{sub 2}MnO{sub 4} (ll0) grown on Nb(0.1wt)-doped SrTiO{sub 3}(110). A magnetic easy axis existed along the elongated tetragonal direction. This was attributed to the strong interplay between the spin and lattice degrees of freedom in the Co{sub 2}MnO{sub 4} thin film.

Leakage current behavior in lead-free ferroelectric (K,Na)NbO3-LiTaO3-LiSbO3 thin films

Science.gov (United States)

Abazari, M.; Safari, A.

2010-12-01

Conduction mechanisms in epitaxial (001)-oriented pure and 1 mol % Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrate were investigated. Temperature dependence of leakage current density was measured as a function of applied electric field in the range of 200-380 K. It was shown that the different transport mechanisms dominate in pure and Mn-doped thin films. In pure (KNN-LT-LS) thin films, Poole-Frenkel emission was found to be responsible for the leakage, while Schottky emission was the dominant mechanism in Mn-doped thin films at higher electric fields. This is a remarkable yet clear indication of effect of 1 mol % Mn on the resistive behavior of such thin films.

Preparation and Characterization of Sb2Te3 Thin Films by Coevaporation

Directory of Open Access Journals (Sweden)

Bin Lv

2010-01-01

Full Text Available Deposition of Sb2Te3 thin films on soda-lime glass substrates by coevaporation of Sb and Te is described in this paper. Sb2Te3 thin films were characterized by x-ray diffraction (XRD, x-ray fluorescence (XRF, atomic force microscopy (AFM, x-ray photoelectron spectroscopy (XPS, electrical conductivity measurements, and Hall measurements. The abnormal electrical transport behavior occurred from in situ electrical conductivity measurements. The results indicate that as-grown Sb2Te3 thin films are amorphous and undergo an amorphous-crystalline transition after annealing, and the posttreatment can effectively promote the formation of Sb-Te bond and prevent oxidation of thin film surface.

Voltage transients in thin-film InSb Hall sensor

Directory of Open Access Journals (Sweden)

Alexey Bardin

Full Text Available The work is reached to study temperature transients in thin-film Hall sensors. We experimentally study InSb thin-film Hall sensor. We find transients of voltage with amplitude about 10 μV on the sensor ports after current switching. We demonstrate by direct measurements that the transients is caused by thermo-e.m.f., and both non-stationarity and heterogeneity of temperature in the film. We find significant asymmetry of temperature field for different direction of the current, which is probably related to Peltier effect. The result can be useful for wide range of scientist who works with switching of high density currents in any thin semiconductor films. 2000 MSC: 41A05, 41A10, 65D05, 65D17, Keywords: Thin-films, Semiconductors, Hall sensor, InSb, thermo-e.m.f.

Sb/Mn co-doped oxyfluoride silicate glasses for potential applications in photosynthesis

Energy Technology Data Exchange (ETDEWEB)

Zhu, Chaofeng [Key Laboratory of Processing and Testing Technology of Glass & Functional Ceramics of Shandong Province, Qilu University of Technology, Jinan 250353 (China); Laboratoire des Verres et Céramiques, UMR-CNRS 6226, Université de Rennes 1, Rennes 35042 (France); Zhang, Xianghua, E-mail: xiang-hua.zhang@univ-rennes1.fr [Laboratoire des Verres et Céramiques, UMR-CNRS 6226, Université de Rennes 1, Rennes 35042 (France); Ma, Hongli [Laboratoire des Verres et Céramiques, UMR-CNRS 6226, Université de Rennes 1, Rennes 35042 (France)

2016-03-15

A series of Sb/Mn co-doped oxyfluoride silicate glasses were prepared via the melt-quenching method to explore red luminescent materials for potential applications in photosynthesis of green plants, and these glasses are investigated by means of luminescence decay curves, absorption, emission, and excitation spectra. We find that the as-prepared glasses are transparent in the visible region and can emit strong red light under ultraviolet, purple, and green light excitations. Furthermore, energy transfer from Sb{sup 3+} to Mn{sup 2+} ions occurs in Sb/Mn co-doped glasses. The results demonstrate that the as-prepared Sb/Mn co-doped oxyfluoride silicate glasses may serve as a potential candidate for developing glass greenhouse, which can enhance the utilization of solar energy for the photosynthesis of the green plants.

Linear and nonlinear optical properties of Sb-doped GeSe2 thin films

Science.gov (United States)

Zhang, Zhen-Ying; Chen, Fen; Lu, Shun-Bin; Wang, Yong-Hui; Shen, Xiang; Dai, Shi-Xun; Nie, Qiu-Hua

2015-06-01

Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb-Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices. Project supported by the National Key Basic Research Program of China (Grant No. 2012CB722703), the National Natural Science Foundation of China (Grant No. 61377061), the Young Leaders of Academic Climbing Project of the Education Department of Zhejiang Province, China (Grant No. pd2013092), the Program for Innovative Research Team of Ningbo City, China (Grant No. 2009B217), and the K. C. Wong Magna Fund in Ningbo University, China.

Chemically deposited Sb2S3 thin films for optical recording

International Nuclear Information System (INIS)

Shaji, S; Arato, A; Castillo, G Alan; Palma, M I Mendivil; Roy, T K Das; Krishnan, B; O'Brien, J J; Liu, J

2010-01-01

Laser induced changes in the properties of Sb 2 S 3 thin films prepared by chemical bath deposition are described in this paper. Sb 2 S 3 thin films of thickness 550 nm were deposited from a solution containing SbCl 3 and Na 2 S 2 O 3 at 27 0 C for 5 h. These thin films were irradiated by a 532 nm continuous wave laser beam under different conditions at ambient atmosphere. X-ray diffraction analysis showed amorphous to polycrystalline transformation due to laser exposure of these thin films. Morphology and composition of these films were described. Optical properties of these films before and after laser irradiation were analysed. The optical band gap of the material was decreased due to laser induced crystallization. The results obtained confirm that there is further scope for developing this material as an optical recording media.

AgSbSe{sub 2} and AgSb(S,Se){sub 2} thin films for photovoltaic applications

Energy Technology Data Exchange (ETDEWEB)

Garza, J.G. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Shaji, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Rodriguez, A.C.; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Krishnan, B., E-mail: kbindu_k@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

2011-10-01

Silver antimony selenide (AgSbSe{sub 2}) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb{sub 2}S{sub 3}), silver selenide (Ag{sub 2}Se), selenium (Se) and silver (Ag). Sb{sub 2}S{sub 3} thin film was prepared from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}, Ag{sub 2}Se from a solution containing AgNO{sub 3} and Na{sub 2}SeSO{sub 3} and Se thin films from an acidified solution of Na{sub 2}SeSO{sub 3}, at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10{sup -3} Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe{sub 2} or AgSb(S,Se){sub 2} depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe{sub 2}/Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V{sub oc} = 435 mV and J{sub sc} = 0.08 mA/cm{sup 2} under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe{sub 2} as an absorber material by a non-toxic selenization process is achieved.

Microstructure evolution in pulsed laser deposited epitaxial Ge-Sb-Te chalcogenide thin films

Energy Technology Data Exchange (ETDEWEB)

Ross, Ulrich; Lotnyk, Andriy, E-mail: andriy.lotnyk@iom-leipzig.de; Thelander, Erik; Rauschenbach, Bernd

2016-08-15

The thin film deposition and structure of highly oriented telluride compounds is of particular interest for phase-change applications in next-generation non-volatile memory such as heterostructure designs, as well as for the investigation of novel optical, thermoelectric and ferroelectric properties in layered telluride compounds. In this work, epitaxial Ge-Sb-Te thin films were successfully produced by pulsed laser deposition on silicon with and without amorphous SiO{sub x} interlayer at elevated process temperatures from a Ge{sub 2}Sb{sub 2}Te{sub 5} target. Aberration-corrected high-resolution scanning transmission electron microscopy (STEM) imaging reveals a distinct interface configuration of the trigonal phase connected by a quasi van der Waals gap (vacancy) to the Sb/Te-passivated single crystalline Si substrate, yet also an intermediate textured growth regime in which the substrate symmetry is only weakly coupled to the thin film orientation, as well as strong deviation of composition at high deposition temperatures. Textured growth of Ge-Sb-Te thin film was also observed on SiO{sub x}/Si substrate with no evidence of an intermediate Sb/Te surface layer on top of an SiO{sub x} layer. In addition, particular defect structures formed by local reorganization of the stacking sequence across the vacancy gap are observed and appear to be intrinsic to these van der Waals-layered compounds. Theoretical image simulations of preferred stacking sequences can be matched to individual building blocks in the Ge-Sb-Te grain. - Highlights: • Atomic-resolution Cs-corrected STEM imaging of PLD deposited Ge-Sb-Te thin films. • Changing of overall composition with increasing deposition temperature. • Direct imaging of surface passivation Sb/Te layer at the Ge-Sb-Te/Si(111) interface. • The Sb/Te passivation layer is not a prerequisite for highly oriented growth of Ge-Sb-Te thin films.

Multilayer SnSb4-SbSe Thin Films for Phase Change Materials Possessing Ultrafast Phase Change Speed and Enhanced Stability.

Science.gov (United States)

Liu, Ruirui; Zhou, Xiao; Zhai, Jiwei; Song, Jun; Wu, Pengzhi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-08-16

A multilayer thin film, comprising two different phase change material (PCM) components alternatively deposited, provides an effective means to tune and leverage good properties of its components, promising a new route toward high-performance PCMs. The present study systematically investigated the SnSb 4 -SbSe multilayer thin film as a potential PCM, combining experiments and first-principles calculations, and demonstrated that these multilayer thin films exhibit good electrical resistivity, robust thermal stability, and superior phase change speed. In particular, the potential operating temperature for 10 years is shown to be 122.0 °C and the phase change speed reaches 5 ns in the device test. The good thermal stability of the multilayer thin film is shown to come from the formation of the Sb 2 Se 3 phase, whereas the fast phase change speed can be attributed to the formation of vacancies and a SbSe metastable phase. It is also demonstrated that the SbSe metastable phase contributes to further enhancing the electrical resistivity of the crystalline state and the thermal stability of the amorphous state, being vital to determining the properties of the multilayer SnSb 4 -SbSe thin film.

Study of Sb2S3 thin films deposited by SILAR method

Science.gov (United States)

Deshpande, M. P.; Chauhan, Krishna; Patel, Kiran N.; Rajput, Piyush; Bhoi, Hiteshkumar R.; Chaki, S. H.

2018-05-01

In the present work, we deposited Sb2S3 thin films on glass slide by successive ionic layer adsorption and reaction (SILAR) technique with different time cycles. From EDAX, we could observe that the films were non-stoichiometric and contained few elements from glass slide. X-ray diffraction has shown that these films are orthorhombic in structure from where we have calculated the lattice parameter and crystallize size. SEM images shows that SILAR synthesized Sb2S3 thin films are homogenous and well distributed indicating the formation of uniform thin films at lower concentration. The room temperature Raman spectra of Sb2S3 thin films showed sharp peaks at 250 cm‑1 and 300 cm‑1 for all cases. Room temperature photoluminescence emission spectrum shows broad bands over 430–480 nm range with strong blue emission peak centered at same wavelength of 460 nm (2.70 eV) for all cases.

Stress-Induced Crystallization of Ge-Doped Sb Phase-Change Thin Films

NARCIS (Netherlands)

Eising, Gert; Pauza, Andrew; Kooi, Bart J.

The large effects of moderate stresses on the crystal growth rate in Ge-doped Sb phase-change thin films are demonstrated using direct optical imaging. For Ge6Sb94 and Ge7Sb93 phase-change films, a large increase in crystallization temperature is found when using a polycarbonate substrate instead of

The effect of disorder on electronic and magnetic properties of quaternary Heusler alloy CoFeMnSi with LiMgPbSb-type structure

International Nuclear Information System (INIS)

Feng, Yu; Chen, Hong; Yuan, Hongkuan; Zhou, Ying; Chen, Xiaorui

2015-01-01

Thin films based on Heusler alloy often lost their theoretical predicted ultra-high spin polarization owing to the appearance of disorder. Using the first-principles calculations within density functional theory (DFT), we investigate the effect of disorder including antisite and swap on electronic and magnetic properties of quaternary Heusler alloy CoFeMnSi with LiMgPbSb-type structure. Twelve kinds of antisites and six kinds of swap disorders are proposed and studied comprehensively. In our calculations, Co(Fe)-, Mn(Fe)-, Si(Mn)-antisite and Co–Fe swap disorders are most favorable due to their lowest formation energies. Moreover, the positive binding energies of Co–Fe, Co–Si, Fe–Si and Mn–Si swap disorders with respect to their corresponding antisite disorders indicate that these complex swap disorders are more stable compared with their corresponding isolated antisite disorders. The investigations on density of states (DOS) show that the spin down energy gap of disordered structures suffers contraction and their DOS entirely move towards lower zone. Besides, the 100% spin polarization is maintained in all structures with antisite and swap disorders except for those with Co(Mn)-, Co(Si)-antisite and Co–Mn, Co–Si swap disorders. Therefore, the half-metallicity of quaternary Heusler alloy CoFeMnSi is quite robust against interfering effects such as Si(Mn), Co(Fe) and Co–Fe disorders most possibly formed in the growth. - Highlights: • CoFeMnSi with LiMgPbSb-type structure is found to be a half-metallic ferromagnet. • Si(Mn), Co(Fe), Mn(Fe) antisites and Co–Fe swap disorders are most likely to form. • The half-metallicity of CoFeMnSi is robust against the most possible disorders. • The magnetic moments of the most possible disorders follow the Pauli-Slater rule

Pulsed laser deposition and thermoelectric properties of In-and Yb-doped CoSb3 skutterudite thin films

KAUST Repository

Sarath Kumar, S. R.

2011-07-29

In-and Yb-doped CoSb3 thin films were prepared by pulsed laser deposition. Process optimization studies revealed that a very narrow process window exists for the growth of single-phase skutterudite films. The electrical conductivity and Seebeck coefficient measured in the temperature range 300-700 K revealed an irreversible change on the first heating cycle in argon ambient, which is attributed to the enhanced surface roughness of the films or trace secondary phases. A power factor of 0.68 W m-1 K-1 was obtained at ∼700 K, which is nearly six times lower than that of bulk samples. This difference is attributed to grain boundary scattering that causes a drop in film conductivity. Copyright © Materials Research Society 2011.

Chemical vapor deposition and electric characterization of perovskite oxides LaMO3 (M=Co, Fe, Cr and Mn) thin films

International Nuclear Information System (INIS)

Ngamou, Patrick Herve Tchoua; Bahlawane, Naoufal

2009-01-01

Oxides with a perovskite structure are important functional materials often used for the development of modern devices. In view of extending their applicability, it is necessary to efficiently control their growth as thin films using technologically relevant synthesis methods. Pulsed spray evaporation CVD was used to grow several perovskite-type oxides on planar silicon substrates at temperatures ranging from 500 to 700 deg. C. The optimization of the process control parameters allows the attainment of the perovskite structure as a single phase. The electrical characterization using the temperature-dependent conductivity and thermopower indicates the p-type conduction of the grown films and shows a decreasing concentration of the charge carrier, mobility and band gap energy in the sequence LaCoO 3 >LaMnO 3 >LaCrO 3 >LaFeO 3 . The investigation of the electric properties of the obtained perovskite thin films shows the versatility of CVD as a method for the development of innovative devices. - Graphical abstract: We report a single step deposition of perovskite thin films LaMO 3 (M: Co, Mn, Cr, Fe) using pulsed spray evaporation chemical vapor deposition. Electrical and thermopower properties, similar to these of bulk materials, could promote the development of modern thermoelectric devices based on thin films technology.

NMR-ON on 60CoCo(fcc, hcp, thin film), 52MnCo(fcc), and 90NbCo(fcc)

International Nuclear Information System (INIS)

Zech, E.; Hagn, E.; Ernst, H.; Eska, G.

1978-01-01

With the NMR-ON method the magnetic hyperfine splitting constant of dilute impurities in a ferromagnetic host material (Fe, Ni, Co) can be determined with high accuracy (10 -3 ...10 -4 ). Only few NMR-ON experiments with Co as host lattice have been performed up to now. In constrast to Fe and Ni, two stable modifications exist for Co (fcc and hcp). In the hcp case the magnetic hyperfine field is expected to be anisotropic. Due to the electric field gradient, which is present in this case, a (small) guadrupole interaction is superimposed to the magnetic hyperfine interaction. For 60 CoCo measurements were done on a fcc foil, a hcp single crystal, and on thin films, which were prepared by evaporating Co into glass. For 52 MnCo and 90 NbCo measurements were performed for fcc Co. (Auth.)

AC plasma induced modifications in Sb{sub 2}S{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Calixto-Rodriguez, M; Martinez, H [Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apartado Postal 48-3, 62210, Cuernavaca, Morelos (Mexico); Castillo, F [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510, Mexico D. F. (Mexico); Pena, Y [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, N.L (Mexico); Sanchez-Juarez, A, E-mail: ciro@nucleares.unam.m [Centro de Investigacion en EnergIa, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n Col. Centro, Temixco, Morelos, C.P. 62580 (Mexico)

2010-01-01

Sb{sub 2}S{sub 3} thin films, deposited by the chemical bath deposition method, were treated with N{sub 2} plasma at 3.0 Torr during several minutes. The as-prepared Sb{sub 2}S{sub 3} thin films and films treated with N{sub 2} plasma have been characterized using several techniques. X-ray diffraction studies have shown that plasma treatment induced recrystallization on the as-prepared Sb{sub 2}S{sub 3}thin films. The band gap values decreased from 2.37 to 1.82 eV after plasma treatment, and the electrical conductivity increased from 10{sup 9} to 10{sup 7} ({Omega}cm){sup -1} due to the annealing effect.

Constructing anisotropic single-Dirac-cones in Bi(1-x)Sb(x) thin films.

Science.gov (United States)

Tang, Shuang; Dresselhaus, Mildred S

2012-04-11

The electronic band structures of Bi(1-x)Sb(x) thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness, and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi(1-x)Sb(x) thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band gap, which can be used in a general two-dimensional system that has a nonparabolic dispersion relation as in the Bi(1-x)Sb(x) thin film system. © 2012 American Chemical Society

Chemically deposited Sb{sub 2}S{sub 3} thin films for optical recording

Energy Technology Data Exchange (ETDEWEB)

Shaji, S; Arato, A; Castillo, G Alan; Palma, M I Mendivil; Roy, T K Das; Krishnan, B [Facultad de IngenierIa Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P- 66450 (Mexico); O' Brien, J J; Liu, J, E-mail: bkrishnan@fime.uanl.m [Center for Nanoscience and Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One Univ. Blvd., St. Louis, MO - 63121 (United States)

2010-02-24

Laser induced changes in the properties of Sb{sub 2}S{sub 3} thin films prepared by chemical bath deposition are described in this paper. Sb{sub 2}S{sub 3} thin films of thickness 550 nm were deposited from a solution containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3} at 27 {sup 0}C for 5 h. These thin films were irradiated by a 532 nm continuous wave laser beam under different conditions at ambient atmosphere. X-ray diffraction analysis showed amorphous to polycrystalline transformation due to laser exposure of these thin films. Morphology and composition of these films were described. Optical properties of these films before and after laser irradiation were analysed. The optical band gap of the material was decreased due to laser induced crystallization. The results obtained confirm that there is further scope for developing this material as an optical recording media.

Intrinsic quantum spin Hall and anomalous Hall effects in h-Sb/Bi epitaxial growth on a ferromagnetic MnO2 thin film.

Science.gov (United States)

Zhou, Jian; Sun, Qiang; Wang, Qian; Kawazoe, Yoshiyuki; Jena, Puru

2016-06-07

Exploring a two-dimensional intrinsic quantum spin Hall state with a large band gap as well as an anomalous Hall state in realizable materials is one of the most fundamental and important goals for future applications in spintronics, valleytronics, and quantum computing. Here, by combining first-principles calculations with a tight-binding model, we predict that Sb or Bi can epitaxially grow on a stable and ferromagnetic MnO2 thin film substrate, forming a flat honeycomb sheet. The flatness of Sb or Bi provides an opportunity for the existence of Dirac points in the Brillouin zone, with its position effectively tuned by surface hydrogenation. The Dirac points in spin up and spin down channels split due to the proximity effects induced by MnO2. In the presence of both intrinsic and Rashba spin-orbit coupling, we find two band gaps exhibiting a large band gap quantum spin Hall state and a nearly quantized anomalous Hall state which can be tuned by adjusting the Fermi level. Our findings provide an efficient way to realize both quantized intrinsic spin Hall conductivity and anomalous Hall conductivity in a single material.

Voltage transients in thin-film InSb Hall sensor

Science.gov (United States)

Bardin, Alexey; Ignatjev, Vyacheslav; Orlov, Andrey; Perchenko, Sergey

The work is reached to study temperature transients in thin-film Hall sensors. We experimentally study InSb thin-film Hall sensor. We find transients of voltage with amplitude about 10 μ V on the sensor ports after current switching. We demonstrate by direct measurements that the transients is caused by thermo-e.m.f., and both non-stationarity and heterogeneity of temperature in the film. We find significant asymmetry of temperature field for different direction of the current, which is probably related to Peltier effect. The result can be useful for wide range of scientist who works with switching of high density currents in any thin semiconductor films.

Polarity-dependent resistance switching in GeSbTe phase-change thin films : The importance of excess Sb in filament formation

NARCIS (Netherlands)

Pandian, Ramanathaswamy; Kooi, Bart J.; Oosthoek, Jasper L. M.; van den Dool, Pim; Palasantzas, George; Pauza, Andrew

2009-01-01

We show that polarity-dependent resistance switching in GeSbTe thin films depends strongly on Sb composition by comparing current-voltage characteristics in Sb-excess Ge(2)Sb(2+x)Te(5) and stoichiometric Ge(2)Sb(2)Te(5) samples. This type of switching in Ge(2)Sb(2+x)Te(5) films is reversible with

Nanoporous MnO{sub x} thin-film electrodes synthesized by electrochemical lithiation/delithiation for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Xia, Hui; Lai, Man On; Lu, Li [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

2011-02-15

Nanoporous MnO{sub x} thin-film electrodes are synthesized using a combination of pulsed laser deposition (PLD) and electrochemical lithiation/delithiation methods. A dense Mn{sub 3}O{sub 4} thin-film deposited by PLD can transform into a nanoporous MnO{sub x} thin-film after electrochemical lithiation/delithiation. A nanoporous MnO{sub x} thin-film electrode exhibits significantly improved supercapacitive performance compared with an as-deposited Mn{sub 3}O{sub 4} thin-film electrode. A MnO{sub x} thin-film finally transforms into a MnO{sub 2} thin-film through an electrochemical oxidation process during continuous cyclic voltammetry scanning. (author)

Engineering helimagnetism in MnSi thin films

Directory of Open Access Journals (Sweden)

S. L. Zhang

2016-01-01

Full Text Available Magnetic skyrmion materials have the great advantage of a robust topological magnetic structure, which makes them stable against the superparamagnetic effect and therefore a candidate for the next-generation of spintronic memory devices. Bulk MnSi, with an ordering temperature of 29.5 K, is a typical skyrmion system with a propagation vector periodicity of ∼18 nm. One crucial prerequisite for any kind of application, however, is the observation and precise control of skyrmions in thin films at room-temperature. Strain in epitaxial MnSi thin films is known to raise the transition temperature to 43 K. Here we show, using magnetometry and x-ray spectroscopy, that the transition temperature can be raised further through proximity coupling to a ferromagnetic layer. Similarly, the external field required to stabilize the helimagnetic phase is lowered. Transmission electron microscopy with element-sensitive detection is used to explore the structural origin of ferromagnetism in these Mn-doped substrates. Our work suggests that an artificial pinning layer, not limited to the MnSi/Si system, may enable room temperature, zero-field skyrmion thin-film systems, thereby opening the door to device applications.

Engineering helimagnetism in MnSi thin films

Science.gov (United States)

Zhang, S. L.; Chalasani, R.; Baker, A. A.; Steinke, N.-J.; Figueroa, A. I.; Kohn, A.; van der Laan, G.; Hesjedal, T.

2016-01-01

Magnetic skyrmion materials have the great advantage of a robust topological magnetic structure, which makes them stable against the superparamagnetic effect and therefore a candidate for the next-generation of spintronic memory devices. Bulk MnSi, with an ordering temperature of 29.5 K, is a typical skyrmion system with a propagation vector periodicity of ˜18 nm. One crucial prerequisite for any kind of application, however, is the observation and precise control of skyrmions in thin films at room-temperature. Strain in epitaxial MnSi thin films is known to raise the transition temperature to 43 K. Here we show, using magnetometry and x-ray spectroscopy, that the transition temperature can be raised further through proximity coupling to a ferromagnetic layer. Similarly, the external field required to stabilize the helimagnetic phase is lowered. Transmission electron microscopy with element-sensitive detection is used to explore the structural origin of ferromagnetism in these Mn-doped substrates. Our work suggests that an artificial pinning layer, not limited to the MnSi/Si system, may enable room temperature, zero-field skyrmion thin-film systems, thereby opening the door to device applications.

Engineering helimagnetism in MnSi thin films

Energy Technology Data Exchange (ETDEWEB)

Zhang, S. L.; Hesjedal, T., E-mail: Thorsten.Hesjedal@physics.ox.ac.uk [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, OX1 3PU (United Kingdom); Chalasani, R.; Kohn, A. [Department of Materials Science and Engineering, Tel Aviv University, Ramat Aviv 6997801, Tel Aviv (Israel); Baker, A. A. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, OX1 3PU (United Kingdom); Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE (United Kingdom); Steinke, N.-J. [ISIS, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0QX (United Kingdom); Figueroa, A. I.; Laan, G. van der [Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE (United Kingdom)

2016-01-15

Magnetic skyrmion materials have the great advantage of a robust topological magnetic structure, which makes them stable against the superparamagnetic effect and therefore a candidate for the next-generation of spintronic memory devices. Bulk MnSi, with an ordering temperature of 29.5 K, is a typical skyrmion system with a propagation vector periodicity of ∼18 nm. One crucial prerequisite for any kind of application, however, is the observation and precise control of skyrmions in thin films at room-temperature. Strain in epitaxial MnSi thin films is known to raise the transition temperature to 43 K. Here we show, using magnetometry and x-ray spectroscopy, that the transition temperature can be raised further through proximity coupling to a ferromagnetic layer. Similarly, the external field required to stabilize the helimagnetic phase is lowered. Transmission electron microscopy with element-sensitive detection is used to explore the structural origin of ferromagnetism in these Mn-doped substrates. Our work suggests that an artificial pinning layer, not limited to the MnSi/Si system, may enable room temperature, zero-field skyrmion thin-film systems, thereby opening the door to device applications.

Superlattice-like SnSb{sub 4}/Ga{sub 3}Sb{sub 7} thin films for ultrafast switching phase-change memory application

Energy Technology Data Exchange (ETDEWEB)

Hu, Yifeng [Tongji University, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Functional Materials Research Laboratory, School of Materials Science and Engineering, Shanghai (China); Jiangsu University of Technology, School of Mathematics and Physics, Changzhou (China); He, Zifang; Zhai, Jiwei [Tongji University, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Functional Materials Research Laboratory, School of Materials Science and Engineering, Shanghai (China); Wu, Pengzhi; Lai, Tianshu [Sun Yat-Sen University, State Key Laboratory of Optoelectronic Materials and Technology, Department of Physics, Guangzhou (China); Song, Sannian; Song, Zhitang [Chinese Academy of Sciences, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Shanghai (China)

2015-11-15

The carrier concentration of Sb-rich phase SnSb{sub 4}, Ga{sub 3}Sb{sub 7} and superlattice-like [SnSb{sub 4}(3.5 nm)/Ga{sub 3}Sb{sub 7}(4 nm)]{sub 7} (SLL-7) thin films as a function of annealing temperature was investigated to explain the reason of resistance change. The activation energy for crystallization was calculated with a Kissinger equation to estimate the thermal stability. In order to illuminate the transition mechanisms, the crystallization kinetics of SLL-7 were explored by using Johnson-Mehl-Avrami theory. The obtained values of Avrami indexes indicate that a one-dimensional growth-dominated mechanism is responsible for the set transition of SLL-7 thin film. X-ray diffractometer and Raman scattering spectra were recorded to investigate the change of crystalline structure. The measurement of atomic force microscopy indicated that SLL-7 thin film has a good smooth surface. A picosecond laser pump-probe system was used to test and verify phase-change speed of the SLL-7 thin film. (orig.)

Density functional study of BiSbTeSe{sub 2} topological insulator thin films

Energy Technology Data Exchange (ETDEWEB)

Mohammadpourrad, Zahra; Abolhassani, Mohammadreza [Department of Physics, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

2017-08-15

In this work, using density functional theory calculations, we have investigated the band topology of bulk BiSbTeSe{sub 2} and its thin film electronic properties in several thicknesses. It is one member of the quaternary compounds Bi{sub 2-x}Sb{sub x}Te{sub 3-y}Se{sub y} (BSTS) with the best intrinsic bulk insulating behavior. Based on our calculations we have found that a band inversion at Γ-point is induced when spin-orbit coupling is turned on, with an energy gap of about 0.318 eV. The film thickness has an effect on the surface states such that a gap opens at Dirac point in 6 quintuple-layers film and with decrease in thickness, the magnitude of the gap increases. The atomic contributions have been mapped out for the first few layers of thin films to demonstrate the surface states. The relative charge density has been calculated layer-wise and the penetration depth of the surface states into the bulk region is found to be about 2.5-3.5 quintuple layers, depending on the termination species of thin films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

InSb semiconductors and (In,Mn)Sb diluted magnetic semiconductors. Growth and properties

Energy Technology Data Exchange (ETDEWEB)

Tran, Lien

2011-04-13

This dissertation describes investigations of the growth by molecular beam epitaxy and the characterization of the semiconductor InSb as well as the diluted magnetic semiconductor (DMS) In{sub 1-x}Mn{sub x}Sb. The InSb films were grown on GaAs (001) substrate and Si (001) offcut by 4 toward (110) substrate up to a thickness of about 2 {mu}m, in spite of a large lattice mismatch between the epi-layer and substrate (14.6% between InSb and GaAs, and 19.3% between InSb and Si). After optimizing the growth conditions, the best InSb films grown directly on GaAs without any special technique results in a high crystal quality, low noise, and an electron mobility of 41100 cm{sup 2}/V s Vs with associated electron concentration of 2.9.10{sup 6} cm{sup -3} at 300 K. Such structures could be used, for example, for infrared detector structures. The growth of InSb on Si, however, is a challenge. In order to successfully grow InSb on Si, tilted substrates and the insertion of buffer layers were used, which helps to reduce the lattice mismatch as well as the formation of defects, and hence to improve the crystal quality. An electron mobility of 24000 cm{sup 2}/V s measured at 300 K, with an associated carrier concentration of 2.6.10{sup 1}6 cm{sup -3} is found for the best sample that was grown at 340 C with a 0.06 {mu}m-thick GaSb/AlSb superlattice buffer layer. The smaller value of electron mobility (compared to the best GaAsbased sample) is related to a higher density of microtwins and stacking faults as well as threading dislocations in the near-interface region as shown by transmission electron microscopy. Deep level noise spectra indicate the existence of deep levels in both GaAs and Si-based samples. The samples grown on Si exhibit the lowest Hooge factor at 300 K, lower than the samples grown on GaAs. Taking the optimized growth conditions of InSb/GaAs, the diluted magnetic semiconductor In{sub 1-x}Mn{sub x}Sb/GaAs (001) is prepared by adding a few percent of Mn into the

Growth dependent magnetization reversal in Co2MnAl full Heusler alloy thin films

Science.gov (United States)

Barwal, Vineet; Husain, Sajid; Behera, Nilamani; Goyat, Ekta; Chaudhary, Sujeet

2018-02-01

Angular dependent magnetization reversal has been investigated in Co2MnAl (CMA) full Heusler alloy thin films grown on Si(100) at different growth temperatures (Ts) by DC-magnetron sputtering. An M -shaped curve is observed in the in-plane angular (0°-360°) dependent coercivity (ADC) by magneto-optical Kerr effect measurements. The dependence of the magnetization reversal on Ts is investigated in detail to bring out the structure-property correlation with regards to ADC in these polycrystalline CMA thin films. This magnetization reversal ( M -shaped ADC behavior) is well described by the two-phase model, which is a combination of Kondorsky (domain wall motion) and Stoner Wohlfarth (coherent rotation) models. In this model, magnetization reversal starts with depinning of domain walls, with their gradual displacement explained by the Kondorsky model, and at a higher field (when the domain walls merge), the system follows coherent rotation before reaching its saturation following the Stoner Wohlfarth model. Further, the analysis of angular dependent squareness ratio (Mr/Ms) indicates that our films clearly exhibited twofold uniaxial anisotropy, which is related to self-steering effect arising due to the obliquely incident flux during the film-growth.

Preparation of LiMn2O4 cathode thin films for thin film lithium secondary batteries by a mist CVD process

International Nuclear Information System (INIS)

Tadanaga, Kiyoharu; Yamaguchi, Akihiro; Sakuda, Atsushi; Hayashi, Akitoshi; Tatsumisago, Masahiro; Duran, Alicia; Aparacio, Mario

2014-01-01

Highlights: • LiMn 2 O 4 thin films were prepared by using the mist CVD process. • An aqueous solution of lithium and manganese acetates is used for the precursor solution. • The cell with the LiMn 2 O 4 thin films exhibited a capacity of about 80 mAh/g. • The cell showed good cycling performance during 10 cycles. - Abstract: LiMn 2 O 4 cathode thin films for thin film lithium secondary batteries were prepared by using so-called the “mist CVD process”, employing an aqueous solution of lithium acetate and manganese acetate, as the source of Li and Mn, respectively. The aqueous solution of starting materials was ultrasonically atomized to form mist particles, and mists were transferred by nitrogen gas to silica glass substrate to form thin films. FE-SEM observation revealed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 750 nm were obtained. The electrochemical cell with the thin films obtained by sintering at 700 °C exhibited a capacity of about 80 mAh/g, and the cell showed good cycling performance during 10 cycles

Structural and optical properties of Sb65Se35-xGex thin films

Science.gov (United States)

Saleh, S. A.; Al-Hajry, A.; Ali, H. M.

2011-07-01

Sb65Se35-xGex (x=0-20 at.%) thin films, prepared by the electron beam evaporation technique on ultrasonically cleaned glass substrates at 300 K, were investigated. The amorphous structure of the thin films was confirmed by x-ray diffraction analysis. The structure was deduced from the Raman spectra measured for all germanium contents in the Sb-Se-Ge matrix. The absorption coefficient (α) of the films was determined by optical transmission measurements. The compositional dependence of the optical band gap is discussed in light of topological and chemical ordered network models.

Magnetic and electronic properties of SrMnO3 thin films

Science.gov (United States)

Mandal, Arup Kumar; Panchal, Gyanendra; Choudhary, R. J.; Phase, D. M.

2018-05-01

Single phase hexagonal bulk SrMnO3 (SMO) was prepared by solid state route and it was used for depositing thin films by pulsed laser deposition (PLD) technique on single crystalline (100) oriented SrTiO3 (STO) substrate. X-ray diffraction shows that the thin film is deposited in cubic SrMnO3 phase. From X-ray absorption at the Mn L edge we observed the mixed valency of Mn (Mn3+& Mn4+) due to strain induced by the lattice mismatching between SMO and STO. Due to this mixed valency of Mn ion in SMO film, the ferromagnetic nature is observed at lower temperature because of double exchange. After post annealing with very low oxygen partial pressure, magnetic and electronic property of SMO films are effectively modified.

Control of the magnetic in-plane anisotropy in off-stoichiometric NiMnSb

International Nuclear Information System (INIS)

Gerhard, F.; Schumacher, C.; Gould, C.; Molenkamp, L. W.

2014-01-01

NiMnSb is a ferromagnetic half-metal which, because of its rich anisotropy and very low Gilbert damping, is a promising candidate for applications in information technologies. We have investigated the in-plane anisotropy properties of thin, molecular beam epitaxy-grown NiMnSb films as a function of their Mn concentration. Using ferromagnetic resonance to determine the uniaxial and four-fold anisotropy fields, (2K U )/(M s ) and (2K 1 )/(M s ) , we find that a variation in composition can change the strength of the four-fold anisotropy by more than an order of magnitude and cause a complete 90° rotation of the uniaxial anisotropy. This provides valuable flexibility in designing new device geometries

Picosecond laser pulse-driven crystallization behavior of SiSb phase change memory thin films

International Nuclear Information System (INIS)

Huang Huan; Li Simian; Zhai Fengxiao; Wang Yang; Lai Tianshu; Wu Yiqun; Gan Fuxi

2011-01-01

Highlights: → We reported crystallization dynamics of a novel SiSb phase change material. → We measured optical constants of as-deposited and irradiated SiSb areas. → Optical properties of as-deposited and irradiated SiSb thin film were compared. → Crystallization of irradiated SiSb was confirmed by using AFM and micro-Raman spectra. → The heat conduction effect of lower metal layer of multi-layer films was studied. - Abstract: Transient phase change crystallization process of SiSb phase change thin films under the irradiation of picosecond (ps) laser pulse was studied using time-resolved reflectivity measurements. The ps laser pulse-crystallized domains were characterized by atomic force microscope, Raman spectra and ellipsometrical spectra measurements. A reflectivity contrast of about 15% can be achieved by ps laser pulse-induced crystallization. A minimum crystallization time of 11 ns was achieved by a low-fluence single ps laser pulse after pre-irradiation. SiSb was shown to be very promising for fast phase change memory applications.

Simultaneous ultra-long data retention and low power based on Ge10Sb90/SiO2 multilayer thin films

Science.gov (United States)

You, Haipeng; Hu, Yifeng; Zhu, Xiaoqin; Zou, Hua; Song, Sannian; Song, Zhitang

2018-02-01

In this article, Ge10Sb90/SiO2 multilayer thin films were prepared to improve thermal stability and data retention for phase change memory. Compared with Ge10Sb90 monolayer thin film, Ge10Sb90 (1 nm)/SiO2 (9 nm) multilayer thin film had higher crystallization temperature and resistance contrast between amorphous and crystalline states. Annealed Ge10Sb90 (1 nm)/SiO2 (9 nm) had uniform grain with the size of 15.71 nm. After annealing, the root-mean-square surface roughness for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film increased slightly from 0.45 to 0.53 nm. The amorphization time for Ge10Sb90 (1 nm)/SiO2 (9 nm) thin film (2.29 ns) is shorter than Ge2Sb2Te5 (3.56 ns). The threshold voltage of a cell based on Ge10Sb90 (1 nm)/SiO2 (9 nm) (3.57 V) was smaller than GST (4.18 V). The results indicated that Ge10Sb90/SiO2 was a promising phase change thin film with high thermal ability and low power consumption for phase change memory application.

Development of half metallicity within mixed magnetic phase of Cu1‑x Co x MnSb alloy

Science.gov (United States)

Bandyopadhyay, Abhisek; Neogi, Swarup Kumar; Paul, Atanu; Meneghini, Carlo; Bandyopadhyay, Sudipta; Dasgupta, Indra; Ray, Sugata

2018-05-01

Cubic half-Heusler Cu1‑x Co x MnSb () compounds have been investigated both experimentally and theoretically for their magnetic, transport and electronic properties in search of possible half metallic antiferromagnetism. The systems (Cu,Co)MnSb are of particular interest as the end member alloys CuMnSb and CoMnSb are semi metallic (SM) antiferromagnetic (AFM) and half metallic (HM) ferromagnetic (FM), respectively. Clearly, Co-doping at the Cu-site of CuMnSb introduces changes in the carrier concentration at the Fermi level that may lead to half metallic ground state but there remains a persistent controversy whether the AFM to FM transition occurs simultaneously. Our experimental results reveal that the AFM to FM magnetic transition occurs through a percolation mechanism where Co-substitution gradually suppresses the AFM phase and forces FM polarization around every dopant cobalt. As a result a mixed magnetic phase is realized within this composition range while a nearly HM band structure is developed already at the 10% Co-doping. Absence of T 2 dependence in the resistivity variation at low T-region serves as an indirect proof of opening up an energy gap at the Fermi surface in one of the spin channels. This is further corroborated by the ab initio electronic structure calculations that suggests that a nearly ferromagnetic half-metallic ground state is stabilized by Sb-p holes produced upon Co doping.

Preparation of LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries by a mist CVD process

Energy Technology Data Exchange (ETDEWEB)

Tadanaga, Kiyoharu, E-mail: tadanaga@chem.osakafu-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka, 599-8531 (Japan); Yamaguchi, Akihiro; Sakuda, Atsushi; Hayashi, Akitoshi; Tatsumisago, Masahiro [Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka, 599-8531 (Japan); Duran, Alicia; Aparacio, Mario [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas, Kelsen 5 (Campus de Cantoblanco), Madrid, 28049 (Spain)

2014-05-01

Highlights: • LiMn{sub 2}O{sub 4} thin films were prepared by using the mist CVD process. • An aqueous solution of lithium and manganese acetates is used for the precursor solution. • The cell with the LiMn{sub 2}O{sub 4} thin films exhibited a capacity of about 80 mAh/g. • The cell showed good cycling performance during 10 cycles. - Abstract: LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries were prepared by using so-called the “mist CVD process”, employing an aqueous solution of lithium acetate and manganese acetate, as the source of Li and Mn, respectively. The aqueous solution of starting materials was ultrasonically atomized to form mist particles, and mists were transferred by nitrogen gas to silica glass substrate to form thin films. FE-SEM observation revealed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 750 nm were obtained. The electrochemical cell with the thin films obtained by sintering at 700 °C exhibited a capacity of about 80 mAh/g, and the cell showed good cycling performance during 10 cycles.

Effects of Sb-doping on the grain growth of Cu(In, Ga)Se2 thin films fabricated by means of single-target sputtering

International Nuclear Information System (INIS)

Zhang, Shu; Wu, Lu; Yue, Ruoyu; Yan, Zongkai; Zhan, Haoran; Xiang, Yong

2013-01-01

To investigate the effects of Sb doping on the kinetics of grain growth in Cu(In,Ga)Se 2 (CIGS) thin films during annealing, CIGS thin films were sputtered onto Mo coated substrates from a single CIGS alloy target, followed by chemical bath deposition of Sb 2 S 3 thin layers on top of CIGS layers and subsequent annealing at different temperatures for 30 min in Se vapors. X-ray diffraction results showed that CIGS thin films were obtained directly using the single-target sputtering method. After annealing, the In/Ga ratio in Sb-doped CIGS thin films remained stable compared to undoped film, possibly because Sb can promote the incorporation of Ga into CIGS. The grain growth in CIGS thin films was enhanced after Sb doping, exhibiting significantly larger grains after annealing at 400 °C or 450 °C compared to films without Sb. In particular, the effect was strikingly significant in grain growth across the film thickness, resulting in columnar grain structure in Sb-doped films. This grain growth improvement may be led by the diffusion of Sb from the front surface to the CIGS-Mo back interface, which promoted the mass transport process in CIGS thin films. - Highlights: ► Cu(In,Ga)Se 2 (CIGS) thin films made by sputtering from a single CIGS target. ► Chemical bath deposition used to introduce antimony into CIGS absorber layers. ► In/Ga ratio decreases in Sb-doped annealed films, comparatively to undoped films. ► Sb-doped CIGS films are superior to undoped films in terms of grain-growth kinetics

Controlling compositional homogeneity and crystalline orientation in Bi0.8Sb0.2 thermoelectric thin films

Science.gov (United States)

Rochford, C.; Medlin, D. L.; Erickson, K. J.; Siegal, M. P.

2015-12-01

Compositional-homogeneity and crystalline-orientation are necessary attributes to achieve high thermoelectric performance in Bi1-xSbx thin films. Following deposition in vacuum, and upon air exposure, we find that 50%-95% of the Sb in 100-nm thick films segregates to form a nanocrystalline Sb2O3 surface layer, leaving the film bulk as Bi-metal. However, we demonstrate that a thin SiN capping layer deposited prior to air exposure prevents Sb-segregation, preserving a uniform film composition. Furthermore, the capping layer enables annealing in forming gas to improve crystalline orientations along the preferred trigonal axis, beneficially reducing electrical resistivity.

Controlling compositional homogeneity and crystalline orientation in Bi0.8Sb0.2 thermoelectric thin films

Directory of Open Access Journals (Sweden)

C. Rochford

2015-12-01

Full Text Available Compositional-homogeneity and crystalline-orientation are necessary attributes to achieve high thermoelectric performance in Bi1−xSbx thin films. Following deposition in vacuum, and upon air exposure, we find that 50%–95% of the Sb in 100-nm thick films segregates to form a nanocrystalline Sb2O3 surface layer, leaving the film bulk as Bi-metal. However, we demonstrate that a thin SiN capping layer deposited prior to air exposure prevents Sb-segregation, preserving a uniform film composition. Furthermore, the capping layer enables annealing in forming gas to improve crystalline orientations along the preferred trigonal axis, beneficially reducing electrical resistivity.

Structure and photoluminescence of Mn-passivated nanocrystalline ZnO:S thin films

International Nuclear Information System (INIS)

Tong, Y.H.; Tang, Q.X.; Liu, Y.C.; Shao, C.L.; Xu, C.S.; Liu, Y.X.

2005-01-01

Mn-passivated nanocrystalline ZnO:S thin films were fabricated by thermally oxidizing Mn-doped ZnS (ZnS:Mn) films prepared by electron beam evaporation. Mn was introduced to passivate the surface defects of ZnO and to improve the optical properties. X-ray diffraction (XRD) and photoluminescence (PL) spectra at 81.9 K indicated the S content in ZnO thin film gradually decreased with increasing annealing temperature. The fitted result of the temperature-dependent PL spectra in the range from 81.9 to 302.2 K showed that S dopant could broaden the optical band gap energy of ZnO. Room temperature PL spectra confirmed that the ultraviolet peak shifted to lower energy with the decrease of S content in the thin film because of the Burstein-Moss effect

Negative thermal expansion and magnetocaloric effect in Mn-Co-Ge-In thin films

Science.gov (United States)

Liu, Y.; Qiao, K. M.; Zuo, S. L.; Zhang, H. R.; Kuang, H.; Wang, J.; Hu, F. X.; Sun, J. R.; Shen, B. G.

2018-01-01

MnCoGe-based alloys with magnetostructural transition show giant negative thermal expansion (NTE) behavior and magnetocaloric effects (MCEs) and thus have attracted a lot of attention. However, the drawback of bad mechanical behavior in these alloys obstructs their practical applications. Here, we report the growth of Mn-Co-Ge-In films with thickness of about 45 nm on (001)-LaAlO3, (001)-SrTiO3, and (001)-Al2O3 substrates. The films grown completely overcome the breakable nature of the alloy and promote its multifunctional applications. The deposited films have a textured structure and retain first-order magnetostructural transition. NTE and MCE behaviors associated with the magnetostructural transition have been studied. The films exhibit a completely repeatable NTE around room temperature. NTE coefficient α can be continuously tuned from the ultra-low expansion (α ˜ -2.0 × 10-7/K) to α ˜ -6.56 × 10-6/K, depending on the growth and particle size of the films on different substrates. Moreover, the films exhibit magnetic entropy changes comparable to the well-known metamagnetic films. All these demonstrate potential multifunctional applications of the present films.

Effects of Mn doping on the ferroelectric properties of PZT thin films

International Nuclear Information System (INIS)

Zhang Qi

2004-01-01

The effects of Mn doping on the ferroelectric properties of Pb(Zr 0.3 Ti 0.7 )O 3 (PZT) thin films on Pt/Ti/SiO 2 /Si substrates have been investigated. The composition of the PZT and Mn doping level are Pb(Zr 0.3 Ti 0.7 ) 1-x Mn x O 3 (x = 0,0.2,0.5,1,2,4 mol%). The PZT thin films doped with a small amount of Mn 2+ (x ≤ 1) showed almost no hysteretic fatigue up to 10 10 switching bipolar pulse cycles, coupled with excellent retention properties. However, excessive additions of manganese made the fatigue behaviour worse. We propose that the addition of small amounts of Mn is able to reduce the oxygen vacancy concentration due to the combination of Mn 2+ and oxygen vacancies in PZT films, forming Mn 4+ ions. The interfacial layer between the Pt electrode and PZT films and Mn-doped PZT (x = 4) was detected by measuring the dielectric constant of thin films of different thickness. However, this interfacial layer was not detected in Mn-doped PZT (x = 1). These observations support the concept of the preferential electromigration of oxygen vacancies into sites in planes parallel to the electrodes, which is probably responsible for the hysteretic fatigue

Defect induced activation of Raman silent modes in rf co-sputtered Mn doped ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Yadav, Harish Kumar [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Sreenivas, K [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India); Katiyar, R S [Department of Physics, University of Puerto Rico, San Juan, PR 00931-3343 (Puerto Rico); Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

2007-10-07

We study the influence of Mn doping on the vibrational properties of rf sputtered ZnO thin films. Raman spectra of the Mn doped ZnO samples reveal two additional vibrational modes, in addition to the host phonon modes, at 252 and 524 cm{sup -1}. The intensity of the additional modes increases continuously with Mn concentration in ZnO and can be used as an indication of Mn incorporation in ZnO. The modes are assigned to the activation of ZnO silent modes due to relaxation of Raman selection rules produced by the breakdown of the translational symmetry of the crystal lattice with the incorporation of Mn at the Zn site. Furthermore, the A{sub 1} (LO) mode is observed with very high intensity in the Raman spectra of undoped ZnO thin film and is attributed to the built-in electric field at the grain boundaries.

Defect induced activation of Raman silent modes in rf co-sputtered Mn doped ZnO thin films

International Nuclear Information System (INIS)

Yadav, Harish Kumar; Sreenivas, K; Katiyar, R S; Gupta, Vinay

2007-01-01

We study the influence of Mn doping on the vibrational properties of rf sputtered ZnO thin films. Raman spectra of the Mn doped ZnO samples reveal two additional vibrational modes, in addition to the host phonon modes, at 252 and 524 cm -1 . The intensity of the additional modes increases continuously with Mn concentration in ZnO and can be used as an indication of Mn incorporation in ZnO. The modes are assigned to the activation of ZnO silent modes due to relaxation of Raman selection rules produced by the breakdown of the translational symmetry of the crystal lattice with the incorporation of Mn at the Zn site. Furthermore, the A 1 (LO) mode is observed with very high intensity in the Raman spectra of undoped ZnO thin film and is attributed to the built-in electric field at the grain boundaries

Direct observation of phase transition of GeSbTe thin films by Atomic Force Microscope

Energy Technology Data Exchange (ETDEWEB)

Yang Fei [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Xu Ling, E-mail: xuling@nju.edu.cn [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Zhang Rui; Geng Lei; Tong Liang; Xu Jun [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Su Weining; Yu Yao [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China); Ma Zhongyuan; Chen Kunji [National Laboratory of Solid State Microstructures and Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

2012-10-01

Graphical abstract: Nano-sized marks on GST thin film were fabricated using Conductive-AFM (Atomic Force Microscope). The AFM morphology images show that the marks are ablated at the center and a raised ring surrounding it. Highlights: Black-Right-Pointing-Pointer Microstructure of GeSbTe thin films was characterized by XRD and AFM. Black-Right-Pointing-Pointer Annealing and applying electrical field can induce crystallization on thin film. Black-Right-Pointing-Pointer Conductive-AFM was used to modify the surface of GeSbTe thin film. - Abstract: GeSbTe (GST) thin films were deposited on quartz substrates using electron beam evaporation system and then annealed in nitrogen atmosphere at different temperatures, ranging from 20 Degree-Sign C to 300 Degree-Sign C. X-ray diffraction (XRD) and Atomic Force microscope (AFM) measurements were used to characterize the as-deposited and post-annealed thin films. Annealing treatment was found to induce changes on microstructure, surface roughness and grain size, indicating that with the increase of annealing temperature, the amorphous GST films first changed to face-centered-cubic (fcc) phase and then the stable hexagonal (hex) phase. Meanwhile, conductive-AFM (C-AFM) was used to produce crystallized GST dots on thin films. I-V spectroscopy results show that GST films can switch from amorphous state to crystalline state at threshold voltage. After switching, I-V curve exhibits ohmic characteristic, which is usually observed in crystallized GST films. By applying repeated I-V spectroscopies on the thin films, crystallized nuclei were observed. As the times of I-V spectroscopies increases, the area of written dots increases, and the center of the mark begin to ablate. The AFM images show that the shape of marks is an ablated center with a raised ring surrounding it.

Simultaneous thermal stability and phase change speed improvement of Sn15Sb85 thin film through erbium doping

Science.gov (United States)

Zou, Hua; Zhu, Xiaoqin; Hu, Yifeng; Sui, Yongxing; Sun, Yuemei; Zhang, Jianhao; Zheng, Long; Song, Zhitang

2016-12-01

In general, there is a trade off between the phase change speed and thermal stability in chalcogenide phase change materials, which leads to sacrifice the one in order to ensure the other. For improving the performance, doping is a widely applied technological process. Here, we fabricated Er doped Sn15Sb85 thin films by magnetron sputtering. Compared with the pure Sn15Sb85, we show that Er doped Sn15Sb85 thin films exhibit simultaneous improvement over the thermal stability and the phase change speed. Thus, our results suggest that Er doping provides the opportunity to solve the contradiction. The main reason for improvement of both thermal stability and crystallization speed is due to the existence of Er-Sb and Er-Sn bonds in Er doped Sn15Sb85 films. Hence, Er doped Sn15Sb85 thin films are promising candidates for the phase change memory application, and this method could be extended to other lanthanide-doped phase change materials.

InSb semiconductors and (In,Mn)Sb diluted magnetic semiconductors: Growth and properties

International Nuclear Information System (INIS)

Tran, Lien

2011-01-01

This dissertation describes investigations of the growth by molecular beam epitaxy and the characterization of the semiconductor InSb as well as the diluted magnetic semiconductor (DMS) In 1-x Mn x Sb. The InSb films were grown on GaAs (001) substrate and Si (001) offcut by 4 toward (110) substrate up to a thickness of about 2 μm, in spite of a large lattice mismatch between the epi-layer and substrate (14.6% between InSb and GaAs, and 19.3% between InSb and Si). After optimizing the growth conditions, the best InSb films grown directly on GaAs without any special technique results in a high crystal quality, low noise, and an electron mobility of 41100 cm 2 /V s Vs with associated electron concentration of 2.9.10 6 cm -3 at 300 K. Such structures could be used, for example, for infrared detector structures. The growth of InSb on Si, however, is a challenge. In order to successfully grow InSb on Si, tilted substrates and the insertion of buffer layers were used, which helps to reduce the lattice mismatch as well as the formation of defects, and hence to improve the crystal quality. An electron mobility of 24000 cm 2 /V s measured at 300 K, with an associated carrier concentration of 2.6.10 1 6 cm -3 is found for the best sample that was grown at 340 C with a 0.06 μm-thick GaSb/AlSb superlattice buffer layer. The smaller value of electron mobility (compared to the best GaAsbased sample) is related to a higher density of microtwins and stacking faults as well as threading dislocations in the near-interface region as shown by transmission electron microscopy. Deep level noise spectra indicate the existence of deep levels in both GaAs and Si-based samples. The samples grown on Si exhibit the lowest Hooge factor at 300 K, lower than the samples grown on GaAs. Taking the optimized growth conditions of InSb/GaAs, the diluted magnetic semiconductor In 1-x Mn x Sb/GaAs (001) is prepared by adding a few percent of Mn into the host material InSb during growth. I have

Deposition and Characterization of CVD-Grown Ge-Sb Thin Film Device for Phase-Change Memory Application

Directory of Open Access Journals (Sweden)

C. C. Huang

2012-01-01

Full Text Available Germanium antimony (Ge-Sb thin films with tuneable compositions have been fabricated on SiO2/Si, borosilicate glass, and quartz glass substrates by chemical vapour deposition (CVD. Deposition takes place at atmospheric pressure using metal chloride precursors at reaction temperatures between 750 and 875°C. The compositions and structures of these thin films have been characterized by micro-Raman, scanning electron microscope (SEM with energy dispersive X-ray analysis (EDX and X-ray diffraction (XRD techniques. A prototype Ge-Sb thin film phase-change memory device has been fabricated and reversible threshold and phase-change switching demonstrated electrically, with a threshold voltage of 2.2–2.5 V. These CVD-grown Ge-Sb films show promise for applications such as phase-change memory and optical, electronic, and plasmonic switching.

AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films for solar cell applications

Energy Technology Data Exchange (ETDEWEB)

González, J.O. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); Shaji, S.; Avellaneda, D. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); Universidad Autónoma de Nuevo León-CIIDIT, Apodaca, Nuevo León, México (Mexico); Castillo, A.G.; Roy, T.K. Das [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); and others

2013-05-15

Highlights: ► AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films were formed by heating Na{sub 2}SeSO{sub 3} dipped Sb{sub 2}S{sub 3}/Ag layers. ► S/Se ratio was varied by changing the dipping time in Na{sub 2}SeSO{sub 3} solution. ► Characterized the films using XRD, XPS, SEM, Optical and electrical measurements. ► Band gap engineering of 1−1.1 eV for x = 0.51 and 0.52 respectively. ► PV Glass/FTO/CdS/AgSb(S{sub x}Se{sub 1−x}){sub 2}/C were prepared showing V{sub oc} = 410 mV, J{sub sc} = 5.7 mA/cm{sup 2}. - Abstract: Silver antimony sulfoselenide (AgSb(S{sub x}Se{sub 1−x}){sub 2}) thin films were prepared by heating glass/Sb{sub 2}S{sub 3}/Ag layers after selenization using sodium selenosulphate solution. First, Sb{sub 2}S{sub 3} thin films were deposited on glass substrates from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}. Then Ag thin films were thermally evaporated onto glass/Sb{sub 2}S{sub 3}, followed by selenization by dipping in an acidic solution of Na{sub 2}SeSO{sub 3}. The duration of selenium dipping was varied as 30 min and 2 h. The heating condition was at 350 °C for 1 h in vacuum. Analysis of X-ray diffraction pattern of the thin films formed after heating showed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Morphology and elemental analysis were done by scanning electron microscopy and energy dispersive X-ray detection. Depth profile of composition of the thin films was performed by X-ray Photoelectron Spectroscopy. The spectral study showed the presence of Ag, Sb, S, and Se, and the corresponding binding energy analysis confirmed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Photovoltaic structures (PV) were prepared using AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films as absorber and CdS thin films as window layers on FTO coated glass substrates. The PV structures were heated at 60–80 °C in air for 1 h to improve ohmic contact. Analysis of J–V characteristics of the PV structures showed V

Growth and characterization of chalcostibite CuSbSe2 thin films for photovoltaic application

Science.gov (United States)

Tiwari, Kunal J.; Vinod, Vijay; Subrahmanyam, A.; Malar, P.

2017-10-01

Bulk copper antimony selenide was synthesized using mechanical alloying from the elemental precursors. Phase formation in milled powders was studied using x-ray diffraction (XRD) and Raman spectroscopy studies. The synthesized bulk source after cold compaction was used as source material for thin film deposition by e-beam evaporation. Thin film deposition was carried out at various e-beam current values (Ib ∼30, 40 and 50 mA) and at a substrate temperature of 200 °C. Near stoichiometric CuSbSe2 thin films were obtained for Ib values closer to 50 mA and post annealing at a temperature of 380 °C for 1 h. Thin films deposited using above conditions were found to exhibit an absorption coefficient (α) values of >105 cm-1 and a band gap value ∼1.18 eV that is closer to the reported band gap for CuSbSe2 compound.

Structural transformation and multiferroic properties of single-phase Bi{sub 0.89}Tb{sub 0.11}Fe{sub 1−x}Mn{sub x}O{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Dong, Guohua; Tan, Guoqiang, E-mail: tan3114@163.com; Luo, Yangyang; Liu, Wenlong; Ren, Huijun; Xia, Ao

2014-01-30

Pure BiFeO{sub 3} (BFO) and Tb, Mn co-doped BiFeO{sub 3} (BTFMO) thin films were deposited on SnO{sub 2}: F (FTO)/glass substrates using a chemical solution deposition method. Detailed investigations were made on the influence of (Tb, Mn) co-doping on the structure change and the electric properties of the BFO films. With the co-doping of Tb and Mn, the structural transformation from rhombohedral R3c to triclinic P1 is confirmed through XRD, Rietveld refinement and Raman analysis. XPS analysis clarifies that (Tb, Mn) co-doping avails to decrease oxygen vacancy concentration, showing less Fe{sup 2+} ions in the co-doped BTFMO thin films than that of the pure BFO thin film. Among the co-doped thin films, the BTFM{sub 1}O film shows the highly enhanced ferroelectric properties with a giant remnant polarization value (2P{sub r} = 180.3 μC/cm{sup 2}). The structural transformation, the well-distributed fine grains and the reduction of leakage current favor enhanced ferroelectric property of (Tb, Mn) co-doped BFO films. It is also found that the BTFM{sub 1}O film shows the enhanced ferromagnetism with the saturated magnetization (M{sub s} = 2.5 emu/cm{sup 3}) as a result of the collapse of space modulated spin structure by the structure transformation.

Surfactant assisted electrodeposition of MnO2 thin films: Improved supercapacitive properties

International Nuclear Information System (INIS)

Dubal, D.P.; Kim, W.B.; Lokhande, C.D.

2011-01-01

Highlights: → Effect of Triton X-100 on physico-chemical properties of MnO 2 films. → High supercapacitance of 345 F g -1 . → Charge-discharge, impedance spectroscopy. - Abstract: In order to obtain a high specific capacitance, MnO 2 thin films have been electrodeposited in the presence of a neutral surfactant (Triton X-100). These films were further characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and contact angle measurement. The XRD studies revealed that the electrodeposited MnO 2 films are amorphous and addition of Triton X-100 does not change its amorphous nature. The electrodeposited films of MnO 2 in the presence of the Triton X-100 possess greater porosity and hence greater surface area in relation to the films prepared in the absence of the surfactant. Wettability test showed that the MnO 2 film becomes superhydrophilic from hydrophilic due to Triton X-100. Supercapacitance properties of MnO 2 thin films studied by cyclic voltammetry, galvanostatic charge-discharge cycling and impedance spectroscopy showed maximum supercapacitance for MnO 2 films deposited in presence of Triton X-100 is 345 F g -1 .

Optical Properties of Al- and Sb-Doped CdTe Thin Films

Directory of Open Access Journals (Sweden)

A. A. J. Al-Douri

2010-01-01

Full Text Available Nondoped and (Al, Sb-doped CdTe thin films with 0.5, 1.5, and 2.5  wt.%, respectively, were deposited by thermal evaporation technique under vacuum onto Corning 7059 glass at substrate temperatures ( of room temperature (RT and 423 K. The optical properties of deposited CdTe films such as band gap, refractive index (n, extinction coefficient (, and dielectric coefficients were investigated as function of Al and Sb wt.% doping, respectively. The results showed that films have direct optical transition. Increasing and the wt.% of both types of dopant, the band gap decrease but the optical is constant as n, and real and imaginary parts of the dielectric coefficient increase.

Defect mediated reversible ferromagnetism in Co and Mn doped zinc oxide epitaxial films

Energy Technology Data Exchange (ETDEWEB)

Mal, Siddhartha; Nori, Sudhakar; Narayan, J. [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Mula, Suhrit [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela 769008 (India); Prater, J. T. [Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States)

2012-12-01

We have introduced defects in ZnO (undoped and doped with Co and Mn) epitaxial thin films using laser irradiation from nanosecond laser pulses and thermal annealing in oxygen ambient. In contrast to the as grown samples, the laser irradiated films show a significant increase in conductivity, enhancement in UV emission, while maintaining the same wurtzite crystal structure. Room-temperature ferromagnetism (RTFM) is observed in laser-irradiated samples, which increased with the number of laser pulses up to a certain value where magnetic moment saturates. The induced ferromagnetism as well as the enhanced electrical conductivity can be reversed with thermal annealing in oxygen ambient. The magnetization in Co and Mn doped films was found to be strong function of growth conditions and defect concentration. X-ray diffraction and optical absorption experiments suggested a 2+ valance state and tetrahedral coordination for both Co and Mn ions. There is a simultaneous increase in n-type electrical conductivity with the number of laser pulses and continue to exhibit semiconducting behavior in both undoped and doped films. The saturation magnetization was found to be 0.08 {mu}{sub B}/Co and 0.05 {mu}{sub B}/Mn, much lower than 3.0 {mu}{sub B}/Co and 5.0 {mu}{sub B}/Mn, indicating the prominent role of intrinsic defects in RTFM with some contribution from Co{sup 2+}-oxygen vacancy complexes. We propose a unified mechanism based upon introduction of intrinsic defects to explain RTFM and n-type conductivity enhancements during pulsed laser and thermal annealing.

Structural, optical and magnetic properties of Mn doped ZnO thin films prepared by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Aravind, Arun, E-mail: aruncusat@gmail.com [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi 682 022, Kerala (India); Jayaraj, M.K., E-mail: mkj@cusat.ac.in [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kochi 682 022, Kerala (India); Kumar, Mukesh; Chandra, Ramesh [Nano Science Laboratory, Institute Instrumentation Centre, IIT Roorkee, Roorkee 247 667, Uttarakhand (India)

2012-08-01

Highlights: Black-Right-Pointing-Pointer Defect induced Raman active modes in Mn doped ZnO thin films. Black-Right-Pointing-Pointer Room temperature ferromagnetism. Black-Right-Pointing-Pointer Morphological variations of ZnO thin films with Mn doping. Black-Right-Pointing-Pointer Variation of refractive index of ZnO thin films with Mn doping. - Abstract: Zn{sub 1-x}Mn{sub x}O thin films were grown by pulsed laser deposition. The phase purity and the structure were confirmed by X-ray diffraction studies. The films have a transmittance more than 80% in the visible region. The refractive index of Zn{sub 0.90}Mn{sub 0.10}O films is found to be 1.77 at 550 nm. The presence of non-polar E{sub 2}{sup high} and E{sub 2}{sup low} Raman modes in thin films indicates that 'Mn' doping does not change the wurtzite structure of ZnO. Apart from the normal modes of ZnO the Zn{sub 1-x}Mn{sub x}O ceramic targets show two additional modes at 332 cm{sup -1} (I{sub 1}) and 524 cm{sup -1} (I{sub 2}). The broad Raman peaks (340-600 cm{sup -1}) observed Zn{sub 0.90}Mn{sub 0.10}O thin films can be deconvoluted into five peaks, denoted as P{sub 1}-P{sub 5}. The possible origins of Raman peaks in Zn{sub 1-x}Mn{sub x}O films are the structural disorder and morphological change caused by the Mn dopant. The B{sub 1}{sup low}, {sup 2}B{sub 1}{sup low}, B{sub 1}{sup high} and A{sub 1}{sup LO} modes as well as the surface phonon mode have been observed in heavily Mn-doped ZnO films. Zn{sub 0.98}Mn{sub 0.02}O thin film shows room temperature ferromagnetism. The saturation magnetic moment of the Zn{sub 0.98}Mn{sub 0.02}O thin film is 0.42{mu}{sub B}/Mn atom. The undoped ZnO film prepared under the same condition shows diamagnetic nature. At higher doping concentrations the formation of Mn clusters suppress the room temperature ferromagnetism in Zn{sub 1-x}Mn{sub x}O thin films and shows paramagnetism. XPS confirms the incorporation of Mn{sup 2+} into the ZnO lattice.

Influence of S/Mn molar ratio on the morphology and optical property of γ-MnS thin films prepared by microwave hydrothermal

International Nuclear Information System (INIS)

Yu, Xin; Li-yun, Cao; Jian-feng, Huang; Jia, Liu; Jie, Fei; Chun-yan, Yao

2013-01-01

Highlights: ► The influence of the precursor solution molar ratio of S/Mn. ► The degree of orientation of the γ-MnS film decrease slightly with increasing the S/Mn from 2.0 to 4.0. ► Film quality is strongly affected by the initial nucleation. ► The absorption edge obviously shifts to a higher wavelength with the increase of the S/Mn molar ratio from 2.0 to 4.0. - Abstract: Well crystallized γ-MnS thin films were successfully synthesized at low temperature and short processing time via a novel microwave hydrothermal (M-H) process without any complexing agent by using manganese chloride and thioacetamide as source materials. The influence of different S/Mn molar ratio in the precursor solution on the phase compositions, morphologies and optical properties of the as-deposited films was investigated. The as-deposited γ-MnS thin films were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and ultraviolet–visible (UV–vis). Results show that the wurtzite phase γ-MnS thin films with good crystallization can be achieved when S/Mn molar ratio is controlled at 2.0–4.0. The deposited γ-MnS thin films exhibit (1 0 0) orientation growth with the thickness of 300–500 nm. With the increase of S/Mn molar ratio from 2.0 to 4.0, the orientation growth is weakened while the dense and uniform of the as-deposited γ-MnS thin films are obviously improved and the corresponding band gap of the thin films increase from 3.88 to 3.97 eV.

Disorder dependence of the magnetic moment of the half-metallic ferromagnet NiMnSb from first principles

International Nuclear Information System (INIS)

Orgassa, D.; Fujiwara, H.; Schulthess, T. C.; Butler, W. H.

2000-01-01

Using half-metallic ferromagnets in spin-dependent devices, like spin valves and ferromagnetic tunnel junctions, is expected to increase the device performance. However, using the half-metallic ferromagnet NiMnSb in such devices led to much less than ideal results. One of the possible sources for this behavior is atomic disorder. First-principles calculations of the influence of atomic disorder on the electronic structure of NiMnSb underline the sensitivity of half-metallic properties in NiMnSb to atomic disorder. In this article, we report on the disorder dependence of the total magnetic moment calculated by applying the layer Korringa-Kohn-Rostoker method in conjunction with the coherent potential approximation. We consider the following types of disorder: (1) intermixing of Ni and Mn, (2) partial occupancy of a normally vacant lattice site by Ni and Mn, and (3) partial occupancy of this site by Mn and Sb. In all cases the composition is kept stoichiometric. All three types of disorder decrease the moment monotonically with increasing disorder levels. For the experimentally seen disorder of 5% Mn and 5% Sb on the normally vacant lattice site, the total moment is decreased by 4.1%. The results suggest that precise measurement of the saturation magnetization of NiMnSb thin films can give information on the disorder. (c) 2000 American Institute of Physics

Chemical states and optical properties of thermally evaporated Ge-Te and Ge-Sb-Te amorphous thin films

Energy Technology Data Exchange (ETDEWEB)

Kumar, S.; Singh, D.; Shandhu, S. [Semiconductor Laboratory, Department of Physics, Guru Nanak Dev University Amritsar (India); Thangaraj, R., E-mail: rthangaraj@rediffmail.com [Semiconductor Laboratory, Department of Physics, Guru Nanak Dev University Amritsar (India)

2012-07-15

Thin amorphous films of Ge{sub 22}Sb{sub 22}Te{sub 56} and Ge{sub 50}Te{sub 50} have been prepared from their respective polycrystalline bulk on glass substrates by thermal evaporation technique. The amorphous nature of the films was checked with X-ray diffraction studies. Amorphous-to-crystalline transition of the films has been induced by thermal annealing and the structural phases have been identified by X-ray diffraction. The phase transformation temperature of the films was evaluated by temperature dependent sheet resistance measurement. The chemical structure of the amorphous films has been investigated using X-ray photoelectron spectroscopy and the role of Sb in phase change Ge{sub 22}Sb{sub 22}Te{sub 56} film is discussed. Survey and core level (Ge 3d, Te 3d, Te 4d, Sb 3p, Sb 3d, O 1s, C 1s) band spectra has been recorded and analyzed. For optical studies, the transmittance and the reflectance spectra were measured over the wavelength ranges 400-2500 nm using UV-vis-NIR spectroscopy. The optical band gap, refractive index and extinction coefficient are also presented for thermally evaporated amorphous thin films.

Ferro electrical properties of GeSbTe thin films; Propiedades ferroelectricas de peliculas delgadas de GeSbTe

Energy Technology Data Exchange (ETDEWEB)

Gervacio A, J. J.; Prokhorov, E.; Espinoza B, F. J., E-mail: jgervacio@qro.cinvestav.m [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico)

2011-07-01

The aim of this work is to investigate and compare ferro electrical properties of thin GeSbTe films with composition Ge{sub 4}Sb{sub 1}Te{sub 5} (with well defined ferro electrical properties) and Ge{sub 2}Sb{sub 2}Te{sub 5} using impedance, optical reflection, XRD, DSc and Piezo response Force Microscopy techniques. The temperature dependence of the capacitance in both materials shows an abrupt change at the temperature corresponding to ferroelectric-paraelectric transition and the Curie-Weiss dependence. In Ge{sub 2}Sb{sub 2}Te{sub 5} films this transition corresponds to the end from a NaCl-type to a hexagonal transformation. Piezo response Force Microscopy measurements found ferroelectric domains with dimension approximately equal to the dimension of grains. (Author)

Magnetic neutron diffraction of MnO thin films

International Nuclear Information System (INIS)

Neubeck, W.; Vettier, C.; Mannix, D.; Bernhoeft, N.; Hiess, A.; Ranno, L.; Givord, D.

1999-01-01

We report on magnetic neutron diffraction carried out on various epitaxial MnO(III) thin films grown on sapphire and MgO substrates. In all samples, of masses between 5 and 50 μg, magnetic Bragg peaks have been observed. The films exhibit what appears to be continuous phase-transitions in contrast to the strongly discontinuous transition exhibited by bulk samples. In addition, the Neel temperature of films prepared on sapphire substrates is strongly enhanced above that of the bulk whilst that of the film grown on MgO is depressed. The possibility to measure magnetic excitations in such thin film systems is discussed in the light of promising test results obtained from an inelastic magnetic neutron scattering experiment on the IN8 spectrometer. (authors)

X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

Directory of Open Access Journals (Sweden)

L. J. Collins-McIntyre

2014-12-01

Full Text Available We report the growth of Mn-doped Bi2Se3 thin films by molecular beam epitaxy (MBE, investigated by x-ray diffraction (XRD, atomic force microscopy (AFM, SQUID magnetometry and x-ray magnetic circular dichroism (XMCD. Epitaxial films were deposited on c-plane sapphire substrates by co-evaporation. The films exhibit a spiral growth mechanism typical of this material class, as revealed by AFM. The XRD measurements demonstrate a good crystalline structure which is retained upon doping up to ∼7.5 atomic-% Mn, determined by Rutherford backscattering spectrometry (RBS, and show no evidence of the formation of parasitic phases. However an increasing interstitial incorporation of Mn is observed with increasing doping concentration. A magnetic moment of 5.1 μB/Mn is obtained from bulk-sensitive SQUID measurements, and a much lower moment of 1.6 μB/Mn from surface-sensitive XMCD. At ∼2.5 K, XMCD at the Mn L2,3 edge, reveals short-range magnetic order in the films and indicates ferromagnetic order below 1.5 K.

Surfactant assisted electrodeposition of MnO{sub 2} thin films: Improved supercapacitive properties

Energy Technology Data Exchange (ETDEWEB)

Dubal, D.P. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S.) (India); School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712 (Korea, Republic of); Kim, W.B. [School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712 (Korea, Republic of); Lokhande, C.D., E-mail: l_chandrakant@yahoo.com [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S.) (India)

2011-10-13

Highlights: > Effect of Triton X-100 on physico-chemical properties of MnO{sub 2} films. > High supercapacitance of 345 F g{sup -1}. > Charge-discharge, impedance spectroscopy. - Abstract: In order to obtain a high specific capacitance, MnO{sub 2} thin films have been electrodeposited in the presence of a neutral surfactant (Triton X-100). These films were further characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and contact angle measurement. The XRD studies revealed that the electrodeposited MnO{sub 2} films are amorphous and addition of Triton X-100 does not change its amorphous nature. The electrodeposited films of MnO{sub 2} in the presence of the Triton X-100 possess greater porosity and hence greater surface area in relation to the films prepared in the absence of the surfactant. Wettability test showed that the MnO{sub 2} film becomes superhydrophilic from hydrophilic due to Triton X-100. Supercapacitance properties of MnO{sub 2} thin films studied by cyclic voltammetry, galvanostatic charge-discharge cycling and impedance spectroscopy showed maximum supercapacitance for MnO{sub 2} films deposited in presence of Triton X-100 is 345 F g{sup -1}.

Facile Synthesis of Novel Nanostructured MnO2Thin Films and Their Application in Supercapacitors

Directory of Open Access Journals (Sweden)

Xia H

2009-01-01

Full Text Available Abstract Nanostructured α-MnO2thin films with different morphologies are grown on the platinum substrates by a facile solution method without any assistance of template or surfactant. Microstructural characterization reveals that morphology evolution from dandelion-like spheres to nanoflakes of the as-grown MnO2is controlled by synthesis temperature. The capacitive behavior of the MnO2thin films with different morphologies are studied by cyclic voltammetry. The α-MnO2thin films composed of dandelion-like spheres exhibit high specific capacitance, good rate capability, and excellent long-term cycling stability.

Optical and structural properties of natural MnSeO{sub 4} mineral thin film

Energy Technology Data Exchange (ETDEWEB)

Kariper, Ishak Afsin, E-mail: akariper@gmail.com [Erciyes University, Education Faculty, Kayseri (Turkey)

2017-05-15

Manganese selenite (MnSeO{sub 4}) crystalline thin film has been produced with chemical bath deposition on substrates (commercial glass). Properties of the thin film, such as transmittance, absorption, and optical band gap and refraction index have been investigated via UV/VIS Spectrum. The structural properties of orthorhombic form have been observed in XRD. The structural and optical properties of MnSeO{sub 4} thin films, deposited at different pH levels were analyzed. Some properties of the films have been changed with the change of pH level, which has been deeply investigated. The grain size of MnSeO{sub 4} thin film has reached its highest value at pH 9. The refraction index and extinction coefficient of MnSeO{sub 4} thin films were measured to be 1.53, 2.86, 2.07, 1.53 (refraction index) and 0.005, 0.029, 0.014, 0.005 (extinction coefficient) for grain sizes 21, 13, 26, and 5 nm respectively. The band gaps (Eg) of the films were measured to be 2.06, 2.57, 2.04, and 2.76 eV for the grain sizes mentioned above. The value of dielectric constant at pH 10 was calculated as 1.575. (author)

Simultaneous measurement of trace metal and oxyanion concentrations in water using diffusive gradients in thin films with a chelex-metsorb mixed binding layer

DEFF Research Database (Denmark)

Panther, Jared G.; Bennett, William W.; Welsh, David T.

2014-01-01

A new diffusive gradients in thin films (DGT) technique with a mixed binding layer (Chelex-100 and the titanium dioxide based adsorbent Metsorb) is described for the simultaneous measurement of labile trace metal (Mn, Co, Ni, Cu, Cd, and Pb) and oxyanion (V, As, Mo, Sb, W, and P) concentrations i...

Structure and composition of magnetocaloric Ni-Mn-In-Co thin films on the nanoscale - a TEM study

Energy Technology Data Exchange (ETDEWEB)

Erkartal, Burak; Schuermann, Ulrich; Kienle, Lorenz [Institute for Materials Science, Synthesis and Real Structure, Christian Albrechts University, Kiel (Germany); Duppel, Viola [Nanochemistry Max Planck Institute for Solid State Research, Stuttgart (Germany); Niemann, Robert; Schultz, Ludwig; Faehler, Sebastian [IFW Dresden (Germany)

2012-08-15

A complementary set of electron microscopy techniques is applied for the determination of structural and chemical segregation phenomena within a 300 nm thick metamagnetic Ni-Mn-In-Co thin film. The structure is predominantly composed of distinct modulated martensites of the 5M-, 6M-, 7M-, and 8M-type. Additionally these modulated structures exhibit twinning and stacking disordering. The nature of the disordering and the structural misfit at the twin interface were analyzed via high resolution micrographs. Next to an adhesion layer of Cr interdiffusion on the nanoscale was observed producing a penternary chemically and structurally homogeneous precipitate. The structure can be assigned to a twinned non-modulated pseudocubic model. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

In-Ga-Zn-oxide thin-film transistors with Sb2TeOx gate insulators fabricated by reactive sputtering using a metallic Sb2Te target

International Nuclear Information System (INIS)

Cheong, Woo-Seok

2011-01-01

Using reactive sputtering, we made transparent amorphous Sb 2 TeO x thin films from a metallic Sb 2 Te target in an oxidizing atmosphere. In-Ga-Zn-oxide thin-film transistors (IGZO TFTs) with Sb 2 TeO x gate insulators deposited at room temperature showed a large hysteresis with a counter clockwise direction, which was caused by mobile charges in the gate insulators. The problems of the mobile charges was solved by using Sb 2 TeO x films formed at 250 .deg. C. After the IGZO TFT had been annealed at 200 .deg. C for 1 hour in an O 2 ambient, the mobility of the IGZO TFT was 22.41 cm 2 /Vs, and the drain current on-off ratio was ∼10 8 .

Raman spectroscopy of ZnMnO thin films grown by pulsed laser deposition

Science.gov (United States)

Orozco, S.; Riascos, H.; Duque, S.

2016-02-01

ZnMnO thin films were grown by Pulsed Laser Deposition (PLD) technique onto Silicon (100) substrates at different growth conditions. Thin films were deposited varying Mn concentration, substrate temperature and oxygen pressure. ZnMnO samples were analysed by using Raman Spectroscopy that shows a red shift for all vibration modes. Raman spectra revealed that nanostructure of thin films was the same of ZnO bulk, wurzite hexagonal structure. The structural disorder was manifested in the line width and shape variations of E2(high) and E2(low) modes located in 99 and 434cm-1 respectively, which may be due to the incorporation of Mn ions inside the ZnO crystal lattice. Around 570cm-1 was found a peak associated to E1(LO) vibration mode of ZnO. 272cm-1 suggest intrinsic host lattice defects. Additional mode centred at about 520cm-1 can be overlap of Si and Mn modes.

Buried homojunction in CdS/Sb2Se3 thin film photovoltaics generated by interfacial diffusion

Science.gov (United States)

Zhou, Ying; Li, Yang; Luo, Jiajun; Li, Dengbing; Liu, Xinsheng; Chen, Chao; Song, Huaibing; Ma, Jingyuan; Xue, Ding-Jiang; Yang, Bo; Tang, Jiang

2017-07-01

Antimony selenide (Sb2Se3) emerges as a very promising non-toxic absorber material for thin film photovoltaics, and most of the devices, either in the superstrate or substrate configuration, employed CdS as the buffer layer. Due to the peculiar one-dimensional crystal structure of Sb2Se3, severe interfacial diffusion would be expected. In this letter, the interfacial diffusion in CdS/Sb2Se3 photovoltaics was carefully characterized from a combined material and device physics characterization. The results indicated that a buried homojunction located deep inside the Sb2Se3 absorber layer due to Cd diffusion, instead of the apparent CdS/Sb2Se3 heterojunction, dictated charge separation and device performance in Sb2Se3 thin film solar cells. Cd diffusion converted p-type Sb2Se3 into n-type by introducing a donor level with an activation energy of 0.22 eV. Our studies deepen the understanding of Sb2Se3 photovoltaics and shed light on their further performance optimization.

Strain induced ferromagnetism and large magnetoresistance of epitaxial La1.5Sr0.5CoMnO6 thin films

Science.gov (United States)

Krishna Murthy, J.; Jyotsna, G.; N, Nileena; Anil Kumar, P. S.

2017-08-01

In this study, the structural, magnetic, and magneto-transport properties of La1.5Sr0.5CoMnO6 (LSCMO) thin films deposited on a SrTiO3 (001) substrate were investigated. A normal θ/2θ x-ray diffraction, rocking curve, ϕ-scan, and reciprocal space mapping data showed that prepared LSCMO thin films are single phase and highly strained with epitaxial nature. Temperature vs. magnetization of LSCMO films exhibits strain-induced ferromagnetic ordering with TC ˜ 165 K. In contrast to the bulk samples, there was no exchange bias and canted type antiferromagnetic and spin glass behavior in films having thickness (t) ≤ 26 nm. Temperature dependent resistivity data were explained using Schnakenberg's model and the polaron hopping conduction process. The slope change in resistivity and magnetoresistance maximum (˜65%) around TC indicates the existence of a weak double exchange mechanism between the mixed valence states of transition metal ions. Suppression of spin dependent scattering with the magnetic field is attributed for the large negative magnetoresistance in LSCMO films.

Influence of the additive Ag for crystallization of amorphous Ge-Sb-Te thin films

Energy Technology Data Exchange (ETDEWEB)

Song, Ki-Ho; Kim, Sung-Won; Seo, Jae-Hee [Faculty of Applied Chemical Engineering, Chonnam National University, 300 Yongbong-dong, Kwangju 500-757 (Korea, Republic of); Lee, Hyun-Yong, E-mail: hyleee@chonnam.ac.k [Faculty of Applied Chemical Engineering, Chonnam National University, 300 Yongbong-dong, Kwangju 500-757 (Korea, Republic of)

2009-05-29

We have investigated the optical and amorphous-to-crystalline transition properties in four-types of chalcogenide thin films; Ge{sub 2}Sb{sub 2}Te{sub 5}, Ge{sub 8}Sb{sub 2}Te{sub 11}, Ag-Ge{sub 2}Sb{sub 2}Te{sub 5} and Ag-Ge{sub 8}Sb{sub 2}Te{sub 11}. Crystallization was caused by nano-pulse illumination ({lambda} = 658 nm) with power (P) of 1-17 mW and pulse duration (t) of 10-460 ns, and the morphologies of crystallized spots were observed by SEM and microscope. It was found that the crystallized spot nearby linearly increases in size with increasing the illuminating energy (E = P {center_dot} t) and eventually ablated out by over illumination. Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-vis-IR spectrophotometer. In addition, a speed of amorphous-to-crystalline transition was evaluated by detecting the reflection response signals for the nano-pulse scanning. Conclusively, the Ge{sub 8}Sb{sub 2}Te{sub 11} film has a faster crystallization speed than the Ge{sub 2}Sb{sub 2}Te{sub 5} film despite its higher crystallization temperature. The crystallization speed was largely improved by adding Ag in Ge{sub 2}Sb{sub 2}Te{sub 5} film but not in Ge{sub 8}Sb{sub 2}Te{sub 11} film. To explain these results, we considered a heat confinement by electron hopping.

Development of sputtered CuSbS2 thin films grown by sequential deposition of binary sulfides

Science.gov (United States)

Medina-Montes, M. I.; Vieyra-Brito, O.; Mathews, N. R.; Mathew, X.

2018-05-01

In this work, CuSbS2 thin films were developed by annealing binary precursors deposited sequentially by rf magnetron sputtering. The recrystallization process was optimized and the films were extensively characterized using a number of tools such as XRD, Raman, SEM, energy dispersive x-ray spectroscopy, atomic force microscopy, Hall, UV–vis spectroscopy, Ellipsometry, Seebeck, and photoresponse. The influence of annealing temperature on the structure, morphology, elemental composition, optical and electrical properties are reported. Annealing below 350 °C resulted in famatinite (Cu3SbS4) and chalcostibite (CuSbS2) ternaries as well as binary phases. Phase-pure chalcostibite was obtained in the range of 350 °C–375 °C. At 400 °C, although CuSbS2 was predominant, tetrahedrite phase (Cu12Sb4S13) appeared as an additional phase. The elemental composition of the films was slightly sulfur deficient, and the atomic percentages of Cu, Sb and S showed a dependence on annealing temperature. The material properties of the phase-pure CuSbS2 thin films are: optical band gap in the range of 1.5–1.62 eV, absorption coefficient close to 105 cm‑1, atomic ratios of Cu/Sb ∼1 and (Cu + Sb)/S ∼1.2, crystal size 18.3–24.5 nm and grain size 50–300 nm. The films were photo-sensitive, showed p-type semiconductor behavior. Electrical resistivity, carrier density and hole mobility were 94–459 Ω cm, 1.6–7.0 × 1015 cm‑3 and 8.4–9.5 cm2 V‑1 s respectively.

As-free pnictide LaNi{sub 1-x}Sb{sub 2} thin films grown by reactive molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Retzlaff, Reiner; Buckow, Alexander; Kurian, Jose; Alff, Lambert [Institute of Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, 64287 Darmstadt (Germany)

2012-07-01

We use reactive molecular beam epitaxy (RMBE) as synthesis technique for the search of arsenic free pnictide superconductors. Epitaxial thin films of LaNi{sub 1-x}Sb{sub 2} were grown on (100)MgO substrates from elemental sources by simultaneous evaporation of high purity La, Ni and Sb metals by e-gun. The LaNi{sub 1-x}Sb{sub 2} thin films grow epitaxially and are (00l) oriented with high crystalline quality, as evident from RHEED and X-Ray diffraction studies. The Ni deficient LaNi{sub 1-x}Sb{sub 2} thin films show metallic behavior with a room temperature resistivity of 110 {mu}{Omega} cm, while the stoichiometric compound is a semiconductor/insulator. The isostructural compound with Bi as pnictide shows a superconducting transition with a T{sub C}(0) of 3.1 K.

Elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys studied by the combinatorial thin film approach and ab initio calculations.

Science.gov (United States)

Reeh, S; Kasprzak, M; Klusmann, C D; Stalf, F; Music, D; Ekholm, M; Abrikosov, I A; Schneider, J M

2013-06-19

The elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys with additions of up to 8 at.% X were studied by combinatorial thin film growth and characterization and by ab initio calculations using the disordered local moments (DLM) approach. The lattice parameter and Young's modulus values change only marginally with X. The calculations and experiments are in good agreement. We demonstrate that the elastic properties of transition metal alloyed Fe-Mn can be predicted by the DLM model.

Structural, mechanical, electronic and magnetic properties of a new series of quaternary Heusler alloys CoFeMnZ (Z=Si, As, Sb): A first-principle study

Energy Technology Data Exchange (ETDEWEB)

Elahmar, M.H.; Rached, H.; Rached, D. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences, Université Djillali Liabès de SidiBel-Abbès, SidiBel-Abbès 22000 (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 (Algeria); Murtaza, G. [Materials Modeling Lab, Department of Physics, Islamia College Peshawar, KPK (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Ahmed, W.K. [ERU, College of Engineering, United Arab Emirates University, Al Ain, Abu Dhabi (United Arab Emirates)

2015-11-01

The structural, mechanical, electronic and magnetic properties of the series of Heusler alloys CoFeMnZ (Z=Si, As, and Sb) have been investigated theoretically. The objective is to seek for stable half-metallic ferromagnets materials with Curie temperatures higher than room temperature. The series of CoFeMnZ (Z=Si, As and Sb) is found to exhibit half-metallic ferromagnetism with high magnetic moment and the localized moment in these magnetic compounds resides at the Mn atom. It has been observed that all our compounds have high Curie temperatures with high spin polarizations. - Highlights: • Density functional calculations for CoFeMnZ (Z=Si, As, Sb) compounds are performed. • Half-metallic ferromagnetism in CoFeMnZ (Z=Si, As, Sb) compounds is established. • The magnetic and mechanical properties for CoFeMnZ (Z=As, Sb) are studied for the first time. • The studied compounds possess high Curie temperatures with high spin polarizations.

Engineering the microstructure and magnetism of La2CoMnO6−δ thin films by tailoring oxygen stoichiometry

International Nuclear Information System (INIS)

Galceran, R.; Frontera, C.; Balcells, Ll.; Cisneros-Fernández, J.; López-Mir, L.; Bozzo, B.; Pomar, A.; Sandiumenge, F.; Martínez, B.; Roqueta, J.; Santiso, J.; Bagués, N.

2014-01-01

We report on the magnetic and structural properties of ferromagnetic-insulating La 2 CoMnO 6−δ thin films grown on top of (001) SrTiO 3 substrates by means of RF sputtering technique. Careful structural analysis, by using synchrotron X-ray diffraction, allows identifying two different crystallographic orientations that are closely related to oxygen stoichiometry and to the features (coercive fields and remanence) of the hysteresis loops. Both Curie temperature and magnetic hysteresis turn out to be dependent on the oxygen stoichiometry. In situ annealing conditions allow tailoring the oxygen content of the films, therefore controlling their microstructure and magnetic properties

Volume magnetostriction at the AF-FRI metamagnetic transition in the itinerant-electron system Mn2-xTxSb (T=Co, Cr)

International Nuclear Information System (INIS)

Bartashevich, M.I.; Goto, T.; Baranov, N.V.; Gaviko, V.S.

2004-01-01

Mn 2 Sb is a ferrimagnet, and substitution of Co or Cr for Mn above the critical concentration results in the appearance of a spontaneous first-order magnetic phase transition from ferrimagnetic (FRI) to antiferromagnetic (AF) with decreasing temperature below T t . At T t a first-order field-induced AF-FRI transition is observed at a critical field B c . The spontaneous as well as the field induced AF-FRI transition is accompanied by a significant magnetovolume effect. Magnetization under high pressure up to 12 kbar, magnetostriction of Mn 1.8 Co 0.2 Sb and Mn 1.94 Cr 0.04 Sb as well as thermal expansion of the Mn 1-x Co x Sb system has been measured in order to clarify the origin of the contradictory experimental results on the pressure effect on B c and that on T t , implying opposite changes. The observed differences are explained by the found anomalous change of sign of the magnetovolume effect at the AF-FRI transition with decreasing temperature

Structural, morphological and optical properties of spray deposited Mn-doped CeO2 thin films

International Nuclear Information System (INIS)

Pavan Kumar, CH.S.S.; Pandeeswari, R.; Jeyaprakash, B.G.

2014-01-01

Highlights: • Spray deposited undoped and Mn-doped CeO 2 thin films were polycrystalline. • Complete changeover of surface morphology upon 4 wt% Mn doping. • 4 wt% Mn-doped CeO 2 thin film exhibited a hydrophobic nature. • Optical band-gap decreases beyond 2 wt% Mn doping. - Abstract: Cerium oxide and manganese (Mn) doped cerium oxide thin films on glass substrates were prepared by home built spray pyrolysis system. The effect of Mn doping on the structural, morphological and optical properties of CeO 2 films were studied. It was found that both the undoped and doped CeO 2 films were polycrystalline in nature but the preferential orientation and grain size changed upon doping. Atomic force micrograph showed a complete changeover of surface morphology from spherical to flake upon doping. A water contact angle result displayed the hydrophobic nature of the doped CeO 2 film. Optical properties indicated an increase in band-gap and a decrease in transmittance upon doping owing to Moss–Burstein effect and inverse Moss–Burstein effects. Other optical properties such as refractive index, extinction coefficient and dielectric constant as a function of doping were analysed and reported

Ab initio study of domain structures in half-metallic CoTi{sub 1−x}Mn{sub x}Sb and thermoelectric CoTi{sub 1−x}Sc{sub x}Sb half-Heusler alloys

Energy Technology Data Exchange (ETDEWEB)

Miranda Mena, Joaquin, E-mail: joaquin.miranda@uni-bayreuth.de; Schoberth, Heiko G.; Gruhn, Thomas; Emmerich, Heike

2015-11-25

We present first-principles calculations of the electronic density of state, the structures in CoTi{sub 1−x}Sc{sub x}Sb and CoTi{sub 1−x}Mn{sub x}Sb. In addition for the latter we calculate magnetic moments. Systems with different stoichiometries are compared and low energy configurations are determined using a cluster expansion procedure. For all studied manganese concentrations, x > 0, CoTi{sub 1−x}Mn{sub x}Sb is half-metallic and magnetic, which make it interesting for spintronic applications. In contrast, with increasing scandium concentration, the band gap of CoTi{sub x}Sc{sub 1-x}Sb closes continuously, while the material changes from a semiconductor to a non-magnetic metal. For low Sc doping this material is well suited for thermoelectric applications. The electronic states close to the Fermi energy are strongly influenced by the distribution of Ti and Mn (or Ti and Sc). This has important consequences for the usage of materials in application fields like spintronics and thermoelectrics. In general, a phase separation of the alloys into a Ti rich and a Ti poor phase is energetically favored. Using mean field theory we create a phase diagram that shows the coexistence and the spinodal region. A spontaneous demixing can be used for the creation of nanodomains within the material. In the case of CoTi{sub 1−x}Sc{sub x}Sb, the resulting reduced lattice thermal conductivity is beneficial for thermoelectric applications, while in CoTi{sub 1−x}Mn{sub x}Sb the nanodomains are detrimental for polarization.

Structural and Magnetic Properties of Mn doped ZnO Thin Film Deposited by Pulsed Laser Deposition

KAUST Repository

Baras, Abdulaziz

2011-07-01

Diluted magnetic oxide (DMO) research is a growing field of interdisciplinary study like spintronic devices and medical imaging. A definite agreement among researchers concerning the origin of ferromagnetism in DMO has yet to be reached. This thesis presents a study on the structural and magnetic properties of DMO thin films. It attempts to contribute to the understanding of ferromagnetism (FM) origin in DMO. Pure ZnO and Mn doped ZnO thin films have been deposited by pulsed laser deposition (PLD) using different deposition conditions. This was conducted in order to correlate the change between structural and magnetic properties. Structural properties of the films were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The superconducting quantum interference device (SQUID) was used to investigate the magnetic properties of these films. The structural characterizations showed that the quality of pure ZnO and Mn doped ZnO films increased as oxygen pressure (PO) increased during deposition. All samples were insulators. In Mn doped films, Mn concentration decreased as PO increased. The Mn doped ZnO samples were deposited at 600˚C and oxygen pressure from 50-500mTorr. All Mn doped films displayed room temperature ferromagnetism (RTFM). However, at 5 K a superparamagnetic (SPM) behavior was observed in these samples. This result was accounted for by the supposition that there were secondary phase(s) causing the superparamagnetic behavior. Our findings hope to strengthen existing research on DMO origins and suggest that secondary phases are the core components that suppress the ferromagnetism. Although RTFM and SPM at low temperature has been observed in other systems (e.g., Co doped ZnO), we are the first to report this behavior in Mn doped ZnO. Future research might extend the characterization and exploration of ferromagnetism in this system.

Fabrication of fully epitaxial magnetic tunnel junctions with a Co2MnSi thin film and a MgO tunnel barrier

International Nuclear Information System (INIS)

Kijima, H.; Ishikawa, T.; Marukame, T.; Matsuda, K.-I.; Uemura, T.; Yamamoto, M.

2007-01-01

Fully epitaxial magnetic tunnel junctions (MTJs) were fabricated with a Co-based full-Heusler alloy Co 2 MnSi (CMS) thin film having the ordered L2 1 structure as a lower electrode, a MgO tunnel barrier, and a Co 50 Fe 50 upper electrode. Reflection high-energy electron diffraction patterns observed in situ for each layer in the MTJ layer structure during fabrication clearly indicated that all layers of the CMS lower electrode, MgO tunnel barrier, and Co 50 Fe 50 upper electrode grew epitaxially. The microfabricated fully epitaxial CMS/MgO/Co 50 Fe 50 MTJs demonstrated relatively high tunnel magnetoresistance ratios of 90% at room temperature and 192% at 4.2 K

Biocorrosion investigation of two shape memory nickel based alloys: Ni-Mn-Ga and thin film NiTi.

Science.gov (United States)

Stepan, L L; Levi, D S; Gans, E; Mohanchandra, K P; Ujihara, M; Carman, G P

2007-09-01

Thin film nitinol and single crystal Ni-Mn-Ga represent two new shape memory materials with potential to be used as percutaneously placed implant devices. However, the biocompatibility of these materials has not been adequately assessed. Immersion tests were conducted on both thin film nitinol and single crystal Ni-Mn-Ga in Hank's balanced salt solution at 37 degrees C and pH 7.4. After 12 h, large pits were found on the Ni-Mn-Ga samples while thin film nitinol displayed no signs of corrosion. Further electrochemical tests on thin film nitinol samples revealed breakdown potentials superior to a mechanically polished nitinol disc. These results suggest that passivation or electropolishing of thin film nitinol maybe unnecessary to promote corrosion resistance.

Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

Directory of Open Access Journals (Sweden)

Hao-Min Xu

2016-11-01

Full Text Available Pure BiFeO3 and heterostructured BiFeO3/BiFe0.95Mn0.05O3 (5% Mn-doped BiFeO3 thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO3 films showed stable and strong response to photo illumination (open circuit potential kept −0.18 V, short circuit photocurrent density was −0.023 mA·cm−2. By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0.95Mn0.05O3 layer and an internal field being built in the BiFeO3/BiFe0.95Mn0.05O3 interface. BiFeO3/BiFe0.95Mn0.05O3 and BiFe0.95Mn0.05O3 thin films demonstrated poor photo activity compared with pure BiFeO3 films, which can be explained by the fact that Mn doping brought in a large amount of defects in the BiFe0.95Mn0.05O3 layers, causing higher carrier combination and correspondingly suppressing the photo response, and this negative influence was more considerable than the positive effects provided by the band modulation.

Growth behavior of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films on graphene substrate grown by plasma-enhanced chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Lee, Chang Wan [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of); Kim, Gun Hwan; Kang, Min A.; An, Ki-Seok; Lee, Young Kuk [Thin Film Materials Research Group, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of); Kang, Seong Gu [School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kim, Hyungjun [School of Electrical and Electronic Engineering, Yonsei University, Seoul (Korea, Republic of)

2017-03-15

A comparative study of the substrate effect on the growth mechanism of chalcogenide Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films was carried out. Obvious microstructural discrepancy in both the as-deposited Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films was observed when grown on graphene or SiO{sub 2}/Si substrate. Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} thin films deposited on the graphene substrate were observed to be grown epitaxially along c-axis and show very smooth surface compared to that on SiO{sub 2}/Si substrate. Based on the experimental results of this study, the initial adsorption sites on graphene substrate during deposition process, which had been discussed theoretically, could be demonstrated empirically. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Sb{sub 7}Te{sub 3}/ZnSb multilayer thin films for high thermal stability and long data retention phase-change memory

Energy Technology Data Exchange (ETDEWEB)

Chen, Shiyu; Wu, Weihua [Functional Materials Research Laboratory, School of Materials Science & Engineering, Tongji University, Shanghai 201804 (China); Zhai, Jiwei, E-mail: apzhai@tongji.edu.cn [Functional Materials Research Laboratory, School of Materials Science & Engineering, Tongji University, Shanghai 201804 (China); Song, Sannian; Song, Zhitang [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Science, Shanghai 200050 (China)

2017-04-15

Highlights: • Sb{sub 7}Te{sub 3} (ST) provides a fast crystallization speed, low melting temperature. • The Sb{sub 7}Te{sub 3}/ZnSb films exhibits faster crystallization speed, high thermal stability. • The calculated temperature for 10-year data retention is about 127 {sup o}C. • The Sb{sub 7}Te{sub 3}/ZnSb multilayer configuration with low power consumption. - Abstract: Phase-change memory is regard as one of the most promising candidates for the next-generation non-volatile memory. In this work, we proposed a Sb{sub 7}Te{sub 3}/ZnSb multilayer thin films to improve the thermal stability of Sb-rich Sb{sub 3}Te{sub 7}. The sheet resistance ratio between amorphous and crystalline states reached up to 4 orders of magnitude. With regard to the thermal stability, the calculated temperature for 10-year data retention is about 127 °C. The threshold current and threshold voltage of a cell based on Sb{sub 7}Te{sub 3}/ZnSb are 6.9 μA and 1.9 V, respectively. The lower RESET power is presented in the PCM cells of Sb{sub 7}Te{sub 3}/ZnSb films, benefiting from its high resistivity.

Synthesis and thin film growth of alkaline cobaltates Na{sub x}CoO{sub 2} and Li{sub x}CoO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Sandra

2013-02-18

In this study sol-gel synthesis was used to fabricate Na{sub x}CoO{sub 2}, LiNi{sub 1/2}Co{sub 1/2}O{sub 2} and LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2}. By using acetate precursors a lower process temperature was accessible, which has a positive effect on the sodium and lithium loss during synthesis. The lithium based powders were single phase and kept cation stoichiometry after sintering. A small grain size is favourable for battery applications. Sodium content was slightly reduced after temperature treatment compared to the initial cation mixture, due to the high volatility of Na. To fabricate thin films PLD was used for deposition. All films were deposited on SrTiO{sub 3} substrates. The growth mechanism of Na{sub x}CoO{sub 2} on SrTiO{sub 3} was investigated and an in-plane and out-of-plane relation between film an substrate was found. The films grow 15 and 45 rotated with respect to the ab-plane of the substrate and grow in c-axis direction out-of-plane. The sodium content and the crystallinity of the Na{sub x}CoO{sub 2} was investigated as a function of the post deposition treatment. A change of x between 0.38 and 0.84 can be achieved. The γ-phase was preserved in all films despite of the change of the sodium content. The in-situ variation of sodium stoichiometry, allows to tune the film properties in a wide range. This feature is an advantage compared to bulk Na{sub x}CoO{sub 2}, in which only certain stoichiometries can be stabilized. Fabrication of superconducting thin films Na{sub 0.33}CoO{sub 2}.1.3H{sub 2}O was challenging, since the superconducting phase is metastable and hardly to stabilize as a thin film. LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} and LiNi{sub 1/2}Co{sub 1/2}O{sub 2} thin films were grown by PLD in (104)-orientation. These thin film materials are promising candidates as cathode materials for the development of thin film batteries.

Direct Demonstration of the Emergent Magnetism Resulting from the Multivalence Mn in a LaMnO3 Epitaxial Thin Film System

DEFF Research Database (Denmark)

Niu, Wei; Liu, Wenqing; Gu, Min

2018-01-01

that play a decisive role in the emergence of ferromagnetism in the otherwise antiferromagnetic LaMnO3 thin films are found. Combining spatially resolved electron energy‐loss spectroscopy, X‐ray absorption spectroscopy, and X‐ray magnetic circular dichroism techniques, it is determined unambiguously...... provide a hitherto‐unexplored multivalence state of Mn on the emergent magnetism in undoped manganite epitaxial thin films, such as LaMnO3 and BiMnO3, and shed new light on all‐oxide spintronic devices....

Polarized Neutron Reflectivity Simulation of Ferromagnet/ Antiferromagnet Thin Films

Energy Technology Data Exchange (ETDEWEB)

Kim, Ki Yeon; Lee, Jeong Soo

2008-02-15

This report investigates the current simulating and fitting programs capable of calculating the polarized neutron reflectivity of the exchange-biased ferromagnet/antiferromagnet magnetic thin films. The adequate programs are selected depending on whether nonspin flip and spin flip reflectivities of magnetic thin films and good user interface are available or not. The exchange-biased systems such as Fe/Cr, Co/CoO, CoFe/IrMn/Py thin films have been simulated successfully with selected programs.

Influence of film thickness and Fe doping on LPG sensing properties of Mn3O4 thin film grown by SILAR method

Science.gov (United States)

Belkhedkar, M. R.; Ubale, A. U.

2018-05-01

Nanocrystalline Fe doped and undoped Mn3O4 thin films have been deposited by Successive Ionic Layer Adsorption and Reaction (SILAR) method onto glass substrates using MnCl2 and NaOH as cationic and anionic precursors. The grazing incidence X-ray diffraction (GIXRD) and field emission scanning electron microscopy (FESEM)) have been carried out to analyze structural and surface morphological properties of the films. The LPG sensing performance of Mn3O4thin films have been studied by varying temperature, concentration of LPG, thickness of the film and doping percentage of Fe. The LPG response of the Mn3O4thin films were found to be enhances with film thickness and decreases with increased Fe doping (0 to 8 wt. %) at 573 K temperature.

Magneto-transport properties of oriented Mn{sub 2}CoAl films sputtered on thermally oxidized Si substrates

Energy Technology Data Exchange (ETDEWEB)

Xu, G. Z.; Du, Y.; Zhang, X. M.; Liu, E. K.; Wang, W. H., E-mail: wenhong.wang@iphy.ac.cn; Wu, G. H. [State Key Laboratory for Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, H. G. [College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)

2014-06-16

Spin gapless semiconductors are interesting family of materials by embracing both magnetism and semiconducting due to their unique band structure. Its potential application in future spintronics requires realization in thin film form. In this Letter, we report fabrication and transport properties of spin gapless Mn{sub 2}CoAl films prepared on thermally oxidized Si substrates by magnetron sputtering deposition. The films deposited at 673 K are well oriented to (001) direction and display a uniform-crystalline surface. Magnetotransport measurements on the oriented films reveal a semiconducting-like resistivity, small anomalous Hall conductivity, and linear magnetoresistance representative of the transport signatures of spin gapless semiconductors. The magnetic properties of the films have also been investigated and compared to that of bulk Mn{sub 2}CoAl, showing small discrepancy induced by the composition deviation.

Characterization of nanostructured Mn3O4 thin films grown by SILAR method at room temperature

International Nuclear Information System (INIS)

Ubale, A.U.; Belkhedkar, M.R.; Sakhare, Y.S.; Singh, Arvind; Gurada, Chetan; Kothari, D.C.

2012-01-01

A novel successive ionic layer adsorption and reaction method has been successfully employed to grow nanostructured conducting nearly transparent thin films of Mn 3 O 4 on to glass substrates at room temperature using MnCl 2 and NaOH as cationic and anionic precursors. The structural and morphological characterizations of the as deposited Mn 3 O 4 films have been carried out by means of X-ray diffraction (XRD), Field Emission Scanning Electron Micrograph (FESEM), EDAX, Atomic Fore Microscopy (AFM) and Fourier Transform Infrared Spectrum (FTIR) analysis. The optical absorption and electrical resistivity measurements were carried out to investigate optical band gap and activation energy of Mn 3 O 4 films deposited by SILAR method. The optical band gap and activation energy of the as deposited film is found to be 2.70 and 0.14 eV respectively. The thermo-emf measurements of Mn 3 O 4 thin film confirm its p-type semiconducting nature. Highlights: ► Nanostructured Mn 3 O 4 thin film is prepared by SILAR method at room temperature. ► The film is nanocrystalline with orthorhombic structure of Mn 3 O 4 . ► The XRD, FTIR, FESEM, EDX and AFM characterization confirms nanocrystalline nature. ► Optical band gap, electrical resistivity and activation energy of film is reported. ► A thermo-emf measurement confirms p-type conductivity of Mn 3 O 4 films.

Improved electrochemical performances of oxygen plasma treated LiMn2O4 thin films

International Nuclear Information System (INIS)

Chen, C C; Chiu, K-F; Lin, K M; Lin, H C; Yang, C-R; Wang, F M

2007-01-01

LiMn 2 O 4 spinel thin films were deposited by radio frequency (rf) magnetron sputtering followed by annealing at 600 0 C in air.The films were then post-treated with an rf driven oxygen plasma. The crystallization and surface morphology of LiMn 2 O 4 thin films were seen to change with rf power. The treated samples were tested under harsh conditions such as deep discharge to 1.5 V and cycling at elevated temperature of 60 0 C to verify the electrochemical performances of LiMn 2 O 4 cathodes. The oxygen plasma treatments improved the electrochemical properties of LiMn 2 O 4 thin films significantly. As the cells were cycled in the range of 4.5-2.0 V at 60 0 C, the samples treated at a proper rf power of 50 W exhibited an initial capacity greater than ∼400 mAh g -1 with reasonable cycling stability. The results were attributed to the change of morphology and the formation of a surface layer induced by the oxygen plasma irradiation

Structural, optical and magnetic properties of Mn diffusion-doped CdS thin films prepared by vacuum evaporation

Energy Technology Data Exchange (ETDEWEB)

Aksu, S. [SoloPower, Inc., 5981 Optical Ct., San Jose, CA 95138 (United States); Bacaksiz, E., E-mail: eminb@ktu.edu.tr [Department of Physics, Karadeniz Technical University, 61080 Trabzon (Turkey); Parlak, M. [Department of Physics, Middle East Technical University, 06531 Ankara (Turkey); Yilmaz, S.; Polat, I.; Altunbas, M. [Department of Physics, Karadeniz Technical University, 61080 Trabzon (Turkey); Tuerksoy, M.; Topkaya, R. [Department of Physics, Gebze Institute of Technology, Gebze, 41400 Kocaeli (Turkey); Ozdogan, K. [Department of Physics, Yildiz Technical University, 34210 Istanbul (Turkey)

2011-10-17

Highlights: {yields} Cadmium sulphide thin films were deposited by vacuum evaporation. {yields} Elemental Mn was deposited onto CdS thin films by using electron beam evaporation and annealed under vacuum at different temperatures. {yields} Structural, optical and magnetic studies of Mn-doped CdS have been investigated. {yields} X-ray diffraction results showed that the undoped CdS film had a zinc-blende structure with a strong preferred orientation along the (1 1 1) direction. {yields} Magnetic measurements show that Mn-doped CdS thin films exhibit a ferromagnetism behavior at room temperature. - Abstract: The effect of Mn-doping on the vacuum deposited CdS thin films has been investigated by studying the changes in the structural, optical and magnetic properties of the films. A thin Mn layer evaporated on the CdS film surface served as the source layer for the diffusion doping. Doping was accomplished by annealing the CdS/Mn stack layers at the temperature range from 300 deg. C to 400 deg. C in step of 50 deg. C for 30 min under vacuum. The X-ray diffraction results showed that the undoped CdS film had a zinc-blende structure with a strong preferred orientation along the (1 1 1) direction. The incorporation of Mn did not cause any change in the texture but reduced the peak intensity and lead to a smaller crystallite size. Investigation of surface morphology using atomic force microscopy confirmed the decrease in the grain size with the Mn diffusion. In addition, a more uniform grain size distribution was observed in the doped films. X-ray photoelectron spectroscopy analysis showed that Mn atoms on the surface of the films were bounded to either sulphur or oxygen atoms. Auger electron spectroscopy of the diffusion-doped CdS sample at 350 deg. C indicated that the atomic Mn concentration was higher close to the surface region and Mn was distributed with a steadily decreasing profile through the bulk of the film with an average atomic concentration value around few

On the structure, morphology, and optical properties of chemical bath deposited Sb2S3 thin films

International Nuclear Information System (INIS)

Krishnan, B.; Arato, A.; Cardenas, E.; Roy, T.K. Das; Castillo, G.A.

2008-01-01

In the present paper, we have reported the room temperature growth of antimony sulphide (Sb 2 S 3 ) thin films by chemical bath deposition and detailed characterization of these films. The films were deposited from a chemical bath containing SbCl 3 and Na 2 S 2 O 3 at 27 deg. C. We have analysed the structure, morphology, composition and optical properties of as deposited Sb 2 S 3 films as well as those subjected to annealing in nitrogen atmosphere or in air. As-deposited films are amorphous to X-ray diffraction (XRD). However, the diffused rings in the electron diffraction pattern revealed the existence of nanocrystalline grains in these films. XRD analysis showed that upon annealing in nitrogen atmosphere these films transformed into polycrystalline with orthorhombic structure. Also, we have observed that during heating in air, Sb 2 S 3 first converts into orthorhombic form and then further heating results in the formation of Sb 2 O 3 crystallites. Optical bandgap energy of as deposited and annealed films was evaluated from UV-vis absorption spectra. The values obtained were 2.57 and 1.73 eV for the as-deposited and the annealed films respectively

Optical and structural properties of CuSbS2 thin films grown by thermal evaporation method

International Nuclear Information System (INIS)

Rabhi, A.; Kanzari, M.; Rezig, B.

2009-01-01

Structural, optical and electrical properties of CuSbS 2 thin films grown by thermal evaporation have been studied relating the effects of substrate heating conditions of these properties. The CuSbS 2 thin films were carried out at substrate temperatures in the temperature range 100-200 deg. C . The structure and composition were characterized by XRD, SEM and EDX. X-ray diffraction revealed that the films are (111) oriented upon substrate temperature 170 deg. C and amorphous for the substrate temperatures below 170 deg. C . No secondary phases are observed for all the films. The optical absorption coefficients and band gaps of the films were estimated by optical transmission and reflection measurements at room temperature. Strong absorption coefficients in the range 10 5 -10 6 cm -1 at 500 nm were found. The direct gaps Eg lie between 0.91-1.89 eV range. It is observed that there is a decrease in optical band gap Eg with increasing the substrate temperature. Resistivity of 0.03-0.96 Ω cm, in dependence on substrate temperature was characterized. The all unheated films exhibit p-type conductivity. The characteristics reported here also offer perspective for CuSbS 2 as an absorber material in solar cells applications

Temperature dependence of the Faraday rotation for CdMnCoTe films

International Nuclear Information System (INIS)

Ahn, J. Y.; Tanaka, M.; Imamura, M.

2001-01-01

The temperature dependence of magneto-optical property in the visible wavelength region has been studied on four-element semimagnetic semiconductor CdMnCoTe films deposited on quartz glass substrates by using MBE equipment. A large dispersion of Faraday rotation was observed, and the peak of the Faraday rotation was shifted to the higher photon energies with increasing Mn concentration at low temperatures. At 180 K, the value of the Faraday rotation observed for the Cd 0.647 Mn 0.34 Co 0.013 Te film on quartz glass was -0.36 deg/cmG at 630 nm. It is equivalent to the value of -0.36 deg/cmG observed at 77 K for the Cd 0.52 Mn 0.48 Te film on quartz glass. At 77 K, the Faraday rotation observed for the Cd 0.647 Mn 0.34 Co 0.013 Te film on quartz glass was -0.49 deg/cmG at 610 nm. The value is approximately two times larger than that of the Cd 0.52 Mn 0.48 Te film deposited on the same quartz glass substrate. The origin of the enhancement of Faraday rotation in CdMnCoTe films has been discussed in terms of the magnetic susceptibility χ. [copyright] 2001 American Institute of Physics

Cu2Sb thin film electrodes prepared by pulsed laser deposition f or lithium batteries

Energy Technology Data Exchange (ETDEWEB)

Song, Seung-Wan; Reade, Ronald P.; Cairns, Elton J.; Vaughey, Jack T.; Thackeray, Michael M.; Striebel, Kathryn A.

2003-08-01

Thin films of Cu2Sb, prepared on stainless steel and copper substrates with a pulsed laser deposition technique at room temperature, have been evaluated as electrodes in lithium cells. The electrodes operate by a lithium insertion/copper extrusion reaction mechanism, the reversibility of which is superior when copper substrates are used, particularly when electrochemical cycling is restricted to the voltage range 0.65-1.4 V vs. Li/Li+. The superior performance of Cu2Sb films on copper is attributed to the more active participation of the extruded copper in the functioning of the electrode. The continual and extensive extrusion of copper on cycling the cells leads to the isolation of Li3Sb particles and a consequent formation of Sb. Improved cycling stability of both types of electrodes was obtained when cells were cycled between 0.65 and 1.4 V. A low-capacity lithium-ion cell with Cu2Sb and LiNi0.8Co0.15Al0.05O2 electrodes, laminated from powders, shows excellent cycling stability over the voltage range 3.15 - 2.2 V, the potential difference corresponding to approximately 0.65-1.4 V for the Cu2Sb electrode vs. Li/Li+. Chemical self-discharge of lithiated Cu2Sb electrodes by reaction with the electrolyte was severe when cells were allowed to relax on open circuit after reaching a lower voltage limit of 0.1 V. The solid electrolyte interphase (SEI) layer formed on Cu2Sb electrodes after cells had been cycled between 1.4 and 0.65 V vs. Li/Li+ was characterized by Fourier-transform infrared spectroscopy; the SEI layer contributes to the large irreversible capacity loss on the initial cycle of these cells. The data contribute to a better understanding of the electrochemical behavior of intermetallic electrodes in rechargeable lithium batteries.

Strain-Induced Ferromagnetism in Antiferromagnetic LuMnO3 Thin Films

Science.gov (United States)

White, J. S.; Bator, M.; Hu, Y.; Luetkens, H.; Stahn, J.; Capelli, S.; Das, S.; Döbeli, M.; Lippert, Th.; Malik, V. K.; Martynczuk, J.; Wokaun, A.; Kenzelmann, M.; Niedermayer, Ch.; Schneider, C. W.

2013-07-01

Single phase and strained LuMnO3 thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1μB), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the antiferromagnetic order are coupled via an exchange field, therefore demonstrating strained rare-earth manganite thin films as promising candidate systems for new multifunctional devices.

Metal-semiconductor transition at a comparable resistivity level and positive magnetoresistance in Mn3Mn1-x Pd x N thin films

Science.gov (United States)

Xu, T.; Ji, G. P.; Cao, Z. X.; Ji, A. L.

2018-02-01

Thin films of antiperovskite Mn3Mn1-x Pd x N with x up to 0.36 were grown by reactive magnetron co-sputtering method. All the deposits exhibit a [1 0 0] preferential orientation, with the lattice constant slightly enlarged in samples with ever more Pd atoms partially substituting the MnI atoms in Mn3MnN matrix. The replacement of MnI atoms in antiperovskite structure by Pd atoms, besides reducing the saturation magnetization, also invokes a metal-semiconductor transition which occurs remarkably at a comparable resistivity level. Moreover, a positive magnetoresistance was observed in samples of a high Pd content. These tunable electrical and magnetic properties of ternary antiperovskite compounds might promise some ingenious applications in electronic industry.

Nanocrystalline LiMn2O4 thin film cathode material prepared by polymer spray pyrolysis method for Li-ion battery

International Nuclear Information System (INIS)

Karthick, S.N.; Richard Prabhu Gnanakan, S.; Subramania, A.; Kim, Hee-Je

2010-01-01

Nanocrystalline cubic spinel lithium manganese oxide thin film was prepared by a polymer spray pyrolysis method using lithium acetate and manganese acetate precursor solution and polyethylene glycol-4000 as a polymeric binder. The substrate temperature was selected from the thermogravimetric analysis by finding the complete crystallization temperature of LiMn 2 O 4 precursor sample. The deposited LiMn 2 O 4 thin films were annealed at 450, 500 and 600 o C for 30 min. The thin film annealed at 600 o C was found to be the sufficient temperature to form high phase pure nanocrystalline LiMn 2 O 4 thin film. The formation of cubic spinel thin film was confirmed by X-ray diffraction study. Scanning electron microscopy and atomic force microscopy analysis revealed that the thin film annealed at 600 o C was found to be nanocrystalline in nature and the surface of the films were uniform without any crack. The electrochemical charge/discharge studies of the prepared LiMn 2 O 4 film was found to be better compared to the conventional spray pyrolysed thin film material.

High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

Science.gov (United States)

Galanakis, I.

2015-03-01

Half-metallic Co2MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co2MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co2MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices.

Structural, morphological and optical properties of spray deposited Mn-doped CeO{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Pavan Kumar, CH.S.S.; Pandeeswari, R.; Jeyaprakash, B.G., E-mail: jp@ece.sastra.edu

2014-07-25

Highlights: • Spray deposited undoped and Mn-doped CeO{sub 2} thin films were polycrystalline. • Complete changeover of surface morphology upon 4 wt% Mn doping. • 4 wt% Mn-doped CeO{sub 2} thin film exhibited a hydrophobic nature. • Optical band-gap decreases beyond 2 wt% Mn doping. - Abstract: Cerium oxide and manganese (Mn) doped cerium oxide thin films on glass substrates were prepared by home built spray pyrolysis system. The effect of Mn doping on the structural, morphological and optical properties of CeO{sub 2} films were studied. It was found that both the undoped and doped CeO{sub 2} films were polycrystalline in nature but the preferential orientation and grain size changed upon doping. Atomic force micrograph showed a complete changeover of surface morphology from spherical to flake upon doping. A water contact angle result displayed the hydrophobic nature of the doped CeO{sub 2} film. Optical properties indicated an increase in band-gap and a decrease in transmittance upon doping owing to Moss–Burstein effect and inverse Moss–Burstein effects. Other optical properties such as refractive index, extinction coefficient and dielectric constant as a function of doping were analysed and reported.

Liquid flow deposited spinel (Ni,Mn){sub 3}O{sub 4} thin films for microbolometer applications

Energy Technology Data Exchange (ETDEWEB)

Le, Duc Thang, E-mail: ducthang36@skku.edu [Intelligent Electronic Component Team, Electronic Materials Convergence Division, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Jeon, Chang Jun; Lee, Kui Woong; Jeong, Young Hun; Yun, Ji Sun [Intelligent Electronic Component Team, Electronic Materials Convergence Division, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Yoon, Dae Ho, E-mail: dhyoon@skku.edu [School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Cho, Jeong Ho, E-mail: goedc@kicet.re.kr [Intelligent Electronic Component Team, Electronic Materials Convergence Division, Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of)

2015-03-01

Highlights: • Highly quality (Ni,Mn){sub 3}O{sub 4} thin films were grown using liquid flow deposited (LFD) technique. • It is possible to deposit multi–component manganite–oxide thin films by LFD at low temperatures. • Nickel–manganite films showed a good negative temperature coefficient (NTC) characteristic. • Liquid flow deposited (Ni,Mn){sub 3}O{sub 4} thin films are very potential for microbolometer applications. - Abstract: A liquid flow deposition (LFD) technique was initially used for the fabrication of single-component Mn{sub 3}O{sub 4} thin films onto Si wafer substrates at a range of substrate temperatures of 30–80 °C, with the introduction of an oxidizing reagent (H{sub 2}O{sub 2}). As a result, solid thin films were well formed from an aqueous solution. An X-ray diffraction (XRD) analysis showed typical characteristics of hausmannite Mn{sub 3}O{sub 4} with a spinel tetragonal phase. Field-emission scanning electron microscopy (FE-SEM) observations revealed nano-sized grains arranged uniformly on a dense and smooth surface for all of the as-deposited films. On the other hand, the LFD method was then extended to prepare two-component nickel–manganite films according to the binary chemical composition of Ni{sub x}Mn{sub 3−x}O{sub 4} with x = 0.02–0.2. The as-grown nickel–manganite films showed a surface with a good quality with a spherical bead-like architecture when x ≤ 0.10, while a conversion from spherical grains into highly porous nanowalls in the microstructure was noted in films when x ≥ 0.12. These results signify that it is possible to fabricate various multi-component manganite-oxide thin films at a low temperature. In addition, the dependences of the room-temperature electrical resistivity (ρ) and the temperature coefficient of resistance (TCR) on the Ni substitution level (x) were investigated on films annealed at 400 °C.

Engineering the microstructure and magnetism of La{sub 2}CoMnO{sub 6−δ} thin films by tailoring oxygen stoichiometry

Energy Technology Data Exchange (ETDEWEB)

Galceran, R.; Frontera, C.; Balcells, Ll.; Cisneros-Fernández, J.; López-Mir, L.; Bozzo, B.; Pomar, A.; Sandiumenge, F.; Martínez, B. [Institut de Ciència de Materials de Barcelona-CSIC, Campus UAB, E-08193 Bellaterra (Spain); Roqueta, J.; Santiso, J. [Institut Català de Nanociència i Nanotecnologia, ICN2-CSIC, Campus UAB, E-08193 Bellaterra (Spain); Bagués, N. [Institut de Ciència de Materials de Barcelona-CSIC, Campus UAB, E-08193 Bellaterra (Spain); Institut Català de Nanociència i Nanotecnologia, ICN2-CSIC, Campus UAB, E-08193 Bellaterra (Spain)

2014-12-15

We report on the magnetic and structural properties of ferromagnetic-insulating La{sub 2}CoMnO{sub 6−δ} thin films grown on top of (001) SrTiO{sub 3} substrates by means of RF sputtering technique. Careful structural analysis, by using synchrotron X-ray diffraction, allows identifying two different crystallographic orientations that are closely related to oxygen stoichiometry and to the features (coercive fields and remanence) of the hysteresis loops. Both Curie temperature and magnetic hysteresis turn out to be dependent on the oxygen stoichiometry. In situ annealing conditions allow tailoring the oxygen content of the films, therefore controlling their microstructure and magnetic properties.

Annealing effects on room temperature thermoelectric performance of p-type thermally evaporated Bi-Sb-Te thin films

Science.gov (United States)

Singh, Sukhdeep; Singh, Janpreet; Tripathi, S. K.

2018-05-01

Bismuth antimony telluride (Bi-Sb-Te) compounds have been investigated for the past many decades for thermoelectric (TE) power generation and cooling purpose. We synthesized this compound with a stoichiometry Bi1.2Sb0.8Te3 through melt cool technique and thin films of as synthesized material were deposited by thermal evaporation. The prime focus of the present work is to study the influence of annealing temperature on the room temperature (RT) power factor of thin films. Electrical conductivity and Seebeck coefficient were studied and power factors were calculated which showed a peak value at 323 K. The compounds performance is comparable to some very efficient Bi-Sb-Te reported stoichiometries at RT scale. The values observed show that material has an enormous potential for energy production at ambient temperature scales.

Structural, dielectric and AC conductivity study of Sb2O3 thin film ...

Indian Academy of Sciences (India)

52

However, to date, no reports have appeared on impedance spectroscopy, modulus behavior, electrical conductivity, dielectric relaxation and dielectric properties of crystalline Sb2O3 thin films. This paper deals for the first time with the frequency and temperature dependence of AC conductivity and complex electric modulus ...

Resistive switching properties of Ce and Mn co-doped BiFeO3 thin films for nonvolatile memory application

Directory of Open Access Journals (Sweden)

Zhenhua Tang

2013-12-01

Full Text Available The Ce and Mn co-doped BiFeO3 (BCFMO thin films were synthesized on Pt/Ti/SiO2/Si substrates using a sol-gel method. The unipolar resistive switching (URS and bipolar resistive switching (BRS behaviors were observed in the Pt/BCFMO/Pt device structure, which was attributed to the formation/rupture of metal filaments. The fabricated device exhibits a large ROFF/RON ratio (>80, long retention time (>105 s and low programming voltages (<1.5 V. Analysis of linear fitting current-voltage curves suggests that the space charge limited leakage current (SCLC and Schottky emission were observed as the conduction mechanisms of the devices.

Mn-doped Ge self-assembled quantum dots via dewetting of thin films

Energy Technology Data Exchange (ETDEWEB)

Aouassa, Mansour, E-mail: mansour.aouassa@yahoo.fr [LMON, Faculté des Sciences de Monastir, Avenue de l’environnement Monastir 5019 (Tunisia); Jadli, Imen [LMON, Faculté des Sciences de Monastir, Avenue de l’environnement Monastir 5019 (Tunisia); Bandyopadhyay, Anup [Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Kim, Sung Kyu [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Yuseong-daero 1689-gil, Yuseong-gu, Daejeon (Korea, Republic of); Department of Materials Science and Engineering, KAIST 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Karaman, Ibrahim [Department of Mechanical Engineering, Texas A& M University, College Station, TX 77843 (United States); Lee, Jeong Yong [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Yuseong-daero 1689-gil, Yuseong-gu, Daejeon (Korea, Republic of); Department of Materials Science and Engineering, KAIST 291 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of)

2017-03-01

Highlights: • We report the new fabrication approach for producing a self- assembled Mn dpoed Ge quantum dots (QDs) on SiO{sub 2} thin film with a Curie temperature above room temperature. These magnetic QDs are crystalline, monodisperse and have a well-defined shape and a controlled size. The investigation opens new routes for elaboration of self-assembled magnetic nanocrystals - Abstract: In this study, we demonstrate an original elaboration route for producing a Mn-doped Ge self-assembled quantum dots on SiO{sub 2} thin layer for MOS structure. These magnetic quantum dots are elaborated using dewetting phenomenon at solid state by Ultra-High Vacuum (UHV) annealing at high temperature of an amorphous Ge:Mn (Mn: 40%) nanolayer deposed at very low temperature by high-precision Solid Source Molecular Beam Epitaxy on SiO{sub 2} thin film. The size of quantum dots is controlled with nanometer scale precision by varying the nominal thickness of amorphous film initially deposed. The magnetic properties of the quantum-dots layer have been investigated by superconducting quantum interference device (SQUID) magnetometry. Atomic force microscopy (AFM), x-ray energy dispersive spectroscopy (XEDS) and transmission electron microscopy (TEM) were used to examine the nanostructure of these materials. Obtained results indicate that GeMn QDs are crystalline, monodisperse and exhibit a ferromagnetic behavior with a Curie temperature (TC) above room temperature. They could be integrated into spintronic technology.

From thermoelectric bulk to nanomaterials: Current progress for Bi2Te3 and CoSb3

International Nuclear Information System (INIS)

Peranio, N.; Eibl, O.; Baessler, S.; Nielsch, K.; Klobes, B.; Hermann, R.P.; Daniel, M.; Albrecht, M.; Goerlitz, H.; Pacheco, V.; Bedoya-Martinez, N.; Hashibon, A.; Elsaesser, C.

2016-01-01

Bi 2 Te 3 and CoSb 3 based nanomaterials were synthesized and their thermoelectric, structural, and vibrational properties analyzed to assess and reduce ZT-limiting mechanisms. The same preparation and/or characterization methods were applied in the different materials systems. Single-crystalline, ternary p-type Bi 15 Sb 29 Te 56 , and n-type Bi 38 Te 55 Se 7 nanowires with power factors comparable to nanostructured bulk materials were prepared by potential-pulsed electrochemical deposition in a nanostructured Al 2 O 3 matrix. p-type Sb 2 Te 3 , n-type Bi 2 Te 3 , and n-type CoSb 3 thin films were grown at room temperature using molecular beam epitaxy and were subsequently annealed at elevated temperatures. This yielded polycrystalline, single phase thin films with optimized charge carrier densities. In CoSb 3 thin films the speed of sound could be reduced by filling the cage structure with Yb and alloying with Fe yielded p-type material. Bi 2 (Te 0.91 Se 0.09 ) 3 /SiC and (Bi 0.26 Sb 0.74 ) 2 Te 3 /SiC nanocomposites with low thermal conductivities and ZT values larger than 1 were prepared by spark plasma sintering. Nanostructure, texture, chemical composition, as well as electronic and phononic excitations were investigated by X-ray diffraction, nuclear resonance scattering, inelastic neutron scattering, Moessbauer spectroscopy, and transmission electron microscopy. For Bi 2 Te 3 materials, ab-initio calculations together with equilibrium and non-equilibrium molecular dynamics simulations for point defects yielded their formation energies and their effect on lattice thermal conductivity, respectively. Current advances in thermoelectric Bi 2 Te 3 and CoSb 3 based nanomaterials are summarized. Advanced synthesis and characterization methods and theoretical modeling were combined to assess and reduce ZT-limiting mechanisms in these materials. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Thermoelectric properties of c-GeSb{sub 0.75}Te{sub 0.5} to h-GeSbTe{sub 0.5} thin films through annealing treatment effects

Energy Technology Data Exchange (ETDEWEB)

Vora-ud, Athorn, E-mail: athornvora-ud@snru.ac.th [Program of Physics, Faculty of Science and Technology, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Thermoelectrics Research Center, Research and Development Institution, Sakon Nakhon Rajabhat University, Mueang District, Sakon Nakhon 47000 (Thailand); Horprathum, Mati, E-mail: mati.horprathum@nectec.or.th [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Eiamchai, Pitak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Muthitamongkol, Pennapa; Chayasombat, Bralee; Thanachayanont, Chanchana [National Metal and Materials Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Pankiew, Apirak [National Electronics and Computer Technology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Klamchuen, Annop [National Nanotechnology Center, National Science and Technology Development Agency, Pathumthani 12120 (Thailand); Naenkieng, Daengdech; Plirdpring, Theerayuth; Harnwunggmoung, Adul [Thermoelectric and Nanotechnology Research Center, Faculty of Science and Technology, Rajamangala University of Technology Suvarnabhumi, Huntra Phranakhon, Si Ayutthaya 13000 (Thailand); Charoenphakdee, Anek [NANO-Thermoelectrics Research Center, Division of Applied Physics, Faculty of Sciences and Liberal Arts, Rajamangala University of Technology Isan, Mueng Nakorn Ratchasima 30000 Thailand (Thailand); Somkhunthot, Weerasak [Program of Physics, Faculty of Science and Technology, Loei Rajabhat University, Muang District, Loei 42000 (Thailand); and others

2015-11-15

Germanium–Antimony–Tellurium (Ge–Sb–Te) thin films were deposited on silicon wafers with 1-μm silicon dioxide (SiO{sub 2}/Si) by pulsed dc magnetron sputtering from a 99.99% GeSbTe target of 1:1:1 ratio at ambient temperature. The samples were annealed at 573, 623, 673, and 723 K for 3600 s in a vacuum state. The effects of the annealing treatment on phase identification, atomic composition, morphology and film thickness, carrier concentration, mobility, and Seebeck coefficient of the Ge–Sb–Te samples have been investigated by grazing-incidence X-ray diffraction, auger electron spectroscopy, field-emission scanning electron microscopy, Hall-effect measurements, and steady state method, respectively. The results demonstrated that the as-deposited Ge–Sb–Te sample was amorphous. Atomic composition of as-deposited and annealed films at 573 K and 623 K were GeSb{sub 0.75}Te{sub 0.5} while annealed films at 673 K and 723 K were GeSbTe{sub 0.5} due to Sb-rich GeSb{sub 0.75}Te{sub 0.5}. The samples annealed at 573 K and 623 K showed the crystal phases of cubic structure (c-GeSb{sub 0.75}Te{sub 0.5}) into hexagonal structure (h-GeSbTe{sub 0.5}) after annealing at 673 K and 723 K. The study demonstrated the insulating condition from the as-deposited GeSbTe film, and the changes towards the thermoelectric properties from the annealing treatments. The GeSbTe films annealed at 673 K yielded excellent thermoelectric properties with the electrical resistivity, Seebeck coefficient, and power factor at approximately 1.45 × 10{sup −5} Ωm, 71.07 μV K{sup −1}, and 3.48 × 10{sup −4} W m{sup −1} K{sup −2}, respectively. - Highlights: • GeSbTe thin films were successfully sputtered for thermoelectric properties. • GeSbTe films were examined among physical, electrical and thermoelectric properties. • Thermoelectric properties were discussed based on composition of the films.

Indium local geometry in In-Sb-Te thin films using XANES and DFT calculations

Science.gov (United States)

Bilovol, V.; Gil Rebaza, A. V.; Mudarra Navarro, A. M.; Errico, L.; Fontana, M.; Arcondo, B.

2017-12-01

In-Sb-Te when is a thin film presents a huge difference in its electrical resistivity when transform from the amorphous (insulating) to the crystalline (conducting) phase. This property made this system one of the main phase-change materials used in the data storage industry. The change in the electrical conductivity is probably associated to a change in the bonding geometry of some of its constituents. To explore this point, we present in this work an study of the bonding geometry of In atoms in In-Sb-Te films by means of In K-edge X-ray absorption near edge structure (XANES) spectroscopy using synchrotron radiation in both as deposited (amorphous) and crystalline thin films obtained as a result of resistance (R) vs temperature (T) measurements. Comparison of the XANES spectra obtained for ternary amorphous films and binary crystalline reference films suggests that in amorphous films the bonding geometry of In atoms is tetrahedral-like. After the thermal annealing has been carried out the differences in the XANES spectra of the as deposited and the annealed films indicate that the bonding geometry of In atoms changes. Based on X-ray diffraction results and ab initio calculations in the framework of the Density Functional Theory (DFT) we show that the new coordination geometry is associated with a tendency of In atoms towards octahedral-like.

Growth and transport properties of thin Co-based Heusler films; Wachstum und Transporteigenschaften duenner Co-basierter Heusler-Filme

Energy Technology Data Exchange (ETDEWEB)

Schneider, Horst

2010-07-01

During this work, thin films of Co-based Heusler compounds were deposited under optimized conditions, and their structural, magnetic, and transport properties were investigated. The growth of the thin film samples was accomplished by two different methods. At first Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al and Co{sub 2}FeSi were deposited by sputter deposition from stoichiometric targets. This is considered the standard technique for the preparation of thin Heusler films. Also for the compounds investigated here it resulted in samples with a high degree of L2{sub 1} ordering. An excess of Fe atoms on Si sites was discovered by a detailed X-ray analysis in conjunction with NMR spectroscopy. The choice of different substrates allowed the adjustment of the growth direction. On the other hand, bulk magnetometry revealed that these sputter deposited films exhibit only a reduced magnetic moment, which is an indication of a reduced spin asymmetry at the Fermi level. One source of this problem seems to be a high residual gas pressure, which leads to an increased sample contamination. To improve this situation, a pulsed laser deposition system was constructed and put into operation. The resulting film growth under ultra-high vacuum conditions led to a further improvement of the short-range crystallographic ordering and a clear enhancement of the magnetic properties. The additional use of a metallic buffer layer resulted in samples with a smooth surface. This opens the door for a number of further analytical experiments, such as tunneling spectroscopy or Brillouin light scattering. After this successful demonstration of this growth technique, an additional method for the flexible variation of the film stoichiometry was implemented. In this work, this method was successfully applied in the deposition of Co{sub 2}Mn{sub 1-x}Fe{sub x}Si films. All samples in this series show a high degree of atomic ordering. Their magnetization values are compatible with the Slater-Pauling rule for

Ab Initio Guided Low Temperature Synthesis Strategy for Smooth Face–Centred Cubic FeMn Thin Films

Directory of Open Access Journals (Sweden)

Friederike Herrig

2018-05-01

Full Text Available The sputter deposition of FeMn thin films with thicknesses in the range of hundred nanometres and beyond requires relatively high growth temperatures for the formation of the face-centred cubic (fcc phase, which results in high thin film roughness. A low temperature synthesis strategy, based on local epitaxial growth of a 100 nm thick fcc FeMn film as well as a Cu nucleation layer on an α-Al2O3 substrate at 160 °C, enables roughness values (Ra as low as ~0.6 nm, which is in the same order of magnitude as the pristine substrate (~0.1 nm. The synthesis strategy is guided by ab initio calculations, indicating very strong interfacial bonding of the Cu nucleation layer to an α-Al2O3 substrate (work of separation 5.48 J/m²—which can be understood based on the high Cu coordination at the interface—and between fcc FeMn and Cu (3.45 J/m². Accompanied by small lattice misfits between these structures, the strong interfacial bonding is proposed to enable the local epitaxial growth of a smooth fcc FeMn thin film. Based on the here introduced synthesis strategy, the implementation of fcc FeMn based thin film model systems for materials with interface dominated properties such as FeMn steels containing κ-carbide precipitates or secondary phases appears meaningful.

Molecular beam epitaxy growth of InSb1−xBix thin films

DEFF Research Database (Denmark)

Song, Yuxin; Wang, Shumin; Saha Roy, Ivy

2013-01-01

Molecular beam epitaxy growth for InSb1−xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are stu...

Quenching of surface traps in Mn doped ZnO thin films for enhanced optical transparency

International Nuclear Information System (INIS)

Ilyas, Usman; Rawat, R.S.; Roshan, G.; Tan, T.L.; Lee, P.; Springham, S.V.; Zhang, Sam; Fengji Li; Chen, R.; Sun, H.D.

2011-01-01

The structural and photoluminescence analyses were performed on un-doped and Mn doped ZnO thin films grown on Si (1 0 0) substrate by pulsed laser deposition (PLD) and annealed at different post-deposition temperatures (500-800 deg. C). X-ray diffraction (XRD), employed to study the structural properties, showed an improved crystallinity at elevated temperatures with a consistent decrease in the lattice parameter 'c'. The peak broadening in XRD spectra and the presence of Mn 2p3/2 peak at ∼640 eV in X-ray Photoelectron Spectroscopic (XPS) spectra of the doped thin films confirmed the successful incorporation of Mn in ZnO host matrix. Extended near band edge emission (NBE) spectra indicated the reduction in the concentration of the intrinsic surface traps in comparison to the doped ones resulting in improved optical transparency. Reduced deep level emission (DLE) spectra in doped thin films with declined PL ratio validated the quenching of the intrinsic surface traps thereby improving the optical transparency and the band gap, essential for optoelectronic and spintronic applications. Furthermore, the formation and uniform distribution of nano-sized grains with improved surface features of Mn-doped ZnO thin films were observed in Field Emission Scanning Electron Microscopy (FESEM) images.

Magnon dispersion in thin magnetic films

International Nuclear Information System (INIS)

Balashov, T; Wulfhekel, W; Buczek, P; Sandratskii, L; Ernst, A

2014-01-01

Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu 3 Au(1 0 0) and present new studies on Co and Ni thin films on Cu(1 0 0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1 0 0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations. (paper)

Magnon dispersion in thin magnetic films.

Science.gov (United States)

Balashov, T; Buczek, P; Sandratskii, L; Ernst, A; Wulfhekel, W

2014-10-01

Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu3Au(1 0 0) and present new studies on Co and Ni thin films on Cu(1 0 0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1 0 0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations.

Photoelectrochemical performance of Mn-TiO{sub 2} thin films mounted on FTO prepared by sol-gel spin coating

Energy Technology Data Exchange (ETDEWEB)

Chen, J.C.; Song, G.H. [National Central Univ., Taoyuan, Taiwan (China). Dept. of Mechanical Engineering; Lu, C.W. [Jen-Teh Junior College, Hou- Lung, Taiwan (China). Dept. of Information Management; Tseng, C.J. [National Central Univ., Chung-Li, Taoyuan County, Taiwan (China). Dept. of Mechanical Engineering; Cheng, K.W. [Chang Gung Univ., Tao-Yuan, Taiwan (China). Dept. of Chemical and Materials Engineering

2009-07-01

Tin oxide (TiO{sub 2}) sol-gels with Mn{sup 2+} molar ratios ranging from 0 to 0.1 per cent were used to form nano-structured Mn(x)Ti(1-x)O(2) thin films. A layer-by-layer spincoating (LLSC) technique was used, in which 10 very thin and uniform coating layers of Mn(x)Ti(1-x)O(2) were deposited on fluorine doped tin oxide (FTO) glass. Properties of the thin films were determined as a function of annealing temperature and molar ratio of the Mn{sup 2+} ions by X-ray diffraction (XRD), scanning electron microscopy (SEM), Atomic Force microscopy (AFM) and photoelectrochemical (PEC) measurements. The PEC measurements were obtained in a dry-type three-electrode cell consisting of sample, platinized and reference Ag/AgCl electrodes. The results revealed that the Mn(x)Ti(1-x)O(2) thin films have better structure and electrochemical characteristics when the annealing temperature is 550 degrees C. The TiO{sub 2} thin films with Mn{sup 2+} ions also had higher photocurrent than undoped TiO{sub 2}. The optimum Mn{sup 2+} loading in this study was found to be 0.1 ml per cent. The maximum photocurrent of Mn(0.1)Ti(0.9)O(2) thin films is about 0.68 mA/cm2 when the bias potential is 0.8 V (vs.Ag/AgCl).

Investigations on Ni-Co-Mn-Sn thin films: Effect of substrate temperature and Ar gas pressure on the martensitic transformations and exchange bias properties

Energy Technology Data Exchange (ETDEWEB)

Machavarapu, Ramudu, E-mail: macrams2@gmail.com; Jakob, Gerhard [Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, D-55128 Mainz (Germany)

2015-03-15

We report the effect of substrate temperature (T{sub S}) and Ar gas pressure (P{sub D}) on the martensitic transformations, magnetic and exchange bias (EB) properties in Heusler type Ni-Co-Mn-Sn epitaxial thin films. Martensitic transformation temperatures and EB fields at 5 K were found to increase with increasing T{sub S}. The observed maximum EB value of 320 Oe after field cooling in the film deposited at 650 {sup ∘}C is high among the values reported for Ni-Mn-Sn thin films which is attributed to the coexistence of ferromagnetic (FM) and antiferromagnetic (AF) phases in the martensitic state. In the case of P{sub D} variation, with increase in P{sub D}, martensitic transformation temperatures were increased and a sharp transformation was observed in the film deposited at 0.06 mbar. Magnetization values at 5 K were higher for increasing P{sub D}. These observations are attributed to the compositional shift. EB effect is also present in these films. Microstructural features observed using atomic force microscopy (AFM) shows a fine twinning and reduced precipitation with increase in P{sub D}, which is also confirmed from the scanning electron microscopy (SEM) images. EB effects in both series were confirmed from the training effect. Target ageing effect has been observed in the films deposited before and after ninety days of time interval. This has been confirmed both on substrate temperature and Ar gas pressure variations.

Chemically synthesis and characterization of MnS thin films by SILAR method

Science.gov (United States)

Yıldırım, M. Ali; Yıldırım, Sümeyra Tuna; Cavanmirza, İlke; Ateş, Aytunç

2016-03-01

MnS thin films were synthesized on glass substrates using SILAR method. The film thickness effect on structural, morphological, optical and electrical properties of the films was investigated. The X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) studies showed that all the films exhibited polycrystalline nature with β-MnS structure and were covered well on glass substrates. The bandgap and resistivity values of the films decreased from 3.39 eV to 2.92 eV and from 11.84 × 106 to 2.21 × 105 Ω-cm as the film thickness increased from 180 to 350 nm, respectively. The refractive index (n) and dielectric constants (ɛo, ɛ∞) values were calculated.

Remarkable strain-induced magnetic anisotropy in epitaxial Co2MnGa (0 0 1) films

International Nuclear Information System (INIS)

Pechan, Michael J.; Yu, Chengtao; Carr, David; Palmstroem, Chris J.

2005-01-01

Remarkably large, strain-induced anisotropy is observed in the thin-film Heusler alloy Co 2 MnGa. 30 nm Co 2 MnGa (0 0 1) films have been epitaxially grown on different interlayers/substrates with varied strain, and investigated with ferromagnetic resonance. The film grown on ErAs/InGaAs/InP experiences tension strain, resulting in an out-of-plane strain-induced anisotropy (∼1.1x10 6 erg/cm 3 ) adding to the effects of shape anisotropy. In contrast, the film grown on ScErAs/GaAs, experiences a compression strain, resulting in an out-of-plane strain-induced anisotropy (∼3.3x10 6 erg/cm 3 ) which almost totally cancels the effects of shape anisotropy, thus rendering the film virtually isotropic. This results in the formation of stripe domains in remanence. In addition, small, but well-defined 2-fold and 4-fold in-plane anisotropy coexist in each sample with weak, but interesting strain dependence. Transport measurement shows small (<1%) magnetoresistance effects in the compression film, but negligible magnetoresistance in the relaxed and tension strained samples

In situ X-ray diffraction study of crystallization process of GeSbTe thin films during heat treatment

International Nuclear Information System (INIS)

Kato, Naohiko; Konomi, Ichiro; Seno, Yoshiki; Motohiro, Tomoyoshi

2005-01-01

The crystallization processes of the Ge 2 Sb 2 Te 5 thin film used for PD and DVD-RAM were studied in its realistic optical disk film configurations for the first time by X-ray diffraction using an intense X-ray beam of a synchrotron orbital radiation facility (SPring-8) and in situ quick detection with a Position-Sensitive-Proportional-Counter. The dependence of the amorphous-to-fcc phase-change temperature T 1 on the rate of temperature elevation R et gave an activation energy E a : 0.93 eV much less than previously reported 2.2 eV obtained from a model sample 25-45 times thicker than in the real optical disks. The similar measurement on the Ge 4 Sb 1 Te 5 film whose large reflectance change attains the readability by CD-ROM drives gave E a : 1.13 eV with larger T 1 than Ge 2 Sb 2 Te 5 thin films at any R et implying a lower sensitivity in erasing as well as a better data stability of the phase-change disk

Effect of tungsten on the phase-change properties of Ge8Sb2Te11 thin films for the phase-change device

Science.gov (United States)

Park, Cheol-Jin; Kong, Heon; Lee, Hyun-Yong; Yeo, Jong-Bin

2017-07-01

In this study, the electrical, optical, and structural properties of tungsten (W)-doped Ge8Sb2Te11 thin films were investigated. Previously, GeSbTe alloys were doped with various materials in an attempt to improve the thermal stability. Ge8Sb2Te11 and W-doped Ge8Sb2Te11 films with a thickness of 200 nm were fabricated by using an RF magnetron reactive co-sputtering system at room temperature on Si ( p-type, 100) and glass substrate. The fabricated thin films were annealed in a furnace in the 0 - 400 ° C temperature range. The optical properties were analyzed using a UV-Vis-IR spectrophotometer, and by using Beer's Law equation, the optical-energy band gap ( E op ), slope B 1/2, and slope 1/ F were calculated. For the crystalline materials, an increase in the slope B 1/2 and 1/ F was observed, exhibiting a good effect on the thermal stability in the amorphous state after the phase change. The structural properties were analyzed by X-ray diffraction, and the result showed that the W-doped Ge8Sb2Te11 had a face-centered-cubic (fcc) crystalline structure increased crystallization temperature ( T c ). An increase in the T c increased the thermal stability in the amorphous state. The electrical properties were analyzed using a 4-point probe, exhibiting an increase in the sheet resistance ( R s ) in the amorphous and the crystalline states indicating a reduced programming current in the memory device.

Stress-induced metallic behavior under magnetic field in Pr1-xCaxMnO3 (x=0.5 and 0.4) thin films (invited)

International Nuclear Information System (INIS)

Prellier, W.; Simon, Ch.; Mercey, B.; Hervieu, M.; Haghiri-Gosnet, A. M.; Saurel, D.; Lecoeur, Ph.; Raveau, B.

2001-01-01

We have investigated the role of the stress induced by the presence of the substrate in thin films of colossal magnetoresistive manganites on structural, resistive, and magnetic properties. Because of the strong coupling between the small structural distortions related to the charge ordering (CO) and the resistive properties, the presence of the substrate prevents the full development of the charge ordering in Pr 0.5 Ca 0.5 MnO 3 , especially in the very thin films. For thicker films, the CO state exists, but is not fully developed. Correlatively, the magnetic field which is necessary to suppress the CO is decreased drastically from 25 T to about 5 T on SrTiO 3 substrates. We have also investigated the influence of the doping level by studying the case of Pr 0.6 Ca 0.4 MnO 3 . [copyright] 2001 American Institute of Physics

The structure and magnetic properties of β-(Ga0.96Mn0.04)2O3 thin film

Science.gov (United States)

Huang, Yuanqi; Chen, Zhengwei; Zhang, Xiao; Wang, Xiaolong; Zhi, Yusong; Wu, Zhenping; Tang, Weihua

2018-05-01

High quality epitaxial single phase (Ga0.96Mn0.04)2O3 and Ga2O3 thin films have been prepared on sapphire substrates by using laser molecular beam epitaxy (L-MBE). X-ray diffraction results indicate that the thin films have the monoclinic structure with a ≤ft( {\\bar 201} \\right) preferable orientation. Room temperature (RT) ferromagnetism appears and the magnetic properties of β-(Ga0.96Mn0.04)2O3 thin film are enhanced compared with our previous works. Experiments as well as the first principle method are used to explain the role of Mn dopant on the structure and magnetic properties of the thin films. The ferromagnetic properties are explained based on the concentration of transition element and the defects in the thin films. Project supported by the National Natural Science Foundation of China (Nos. 11404029, 51572033, 51172208) and the Fund of State Key Laboratory of Information Photonics and Optical Communications (BUPT).

Thin films on icosahedral AlPdMn quasicrystal

Energy Technology Data Exchange (ETDEWEB)

Longchamp, J.N.

2007-07-01

In this project, the oxidation at high temperature of the fivefold-symmetry surface of an icosahedral Al{sub 70}Pd{sub 20}M{sub 10} quasicrystal was principally investigated. The stoichiometry of the near-surface region was investigated by means of Auger electron spectroscopy and X-ray photoelectron spectroscopy and both confirmed the oxidation of only the Al atoms of the quasicrystalline substrate. The affinity of the two structures is illustrated by the CsCl-like AlPd domains observed, by means of secondary-electron imaging, after Ar{sup +}-sputtering of the quasicrystalline surface. In this project, we used the oxidized fivefold-symmetry surface of i-AlPdMn as substrate for the deposition of PbTe and CdTe. Diffraction patterns obtained from thin films of both materials exhibit, instead of the usual spots, diffraction rings. They are characteristics of nanocrystallites having a random azimuthal orientations but a well-defined polar orientation; the (001) face and the (111) face in case of PbTe and CdTe, respectively. From the diffraction patterns, average domain sizes of 35 Aa were deduced. Face-centered-cubic Al(111) domains with a similar average size are observed in this case. Angle-resolved photoemission spectroscopy investigations on the PbTe films were performed. We also performed angle-resolved photoemission spectroscopy measurements on Ag films deposited onto the fivefold-symmetry surface of icosahedral AlPdMn and onto the tenfold-symmetry surface of decagonal AlCoNi as model for confinement effects occurring due to the incompatible symmetries between the crystalline films and the quasicrystalline surfaces. By analyzing the Ag sp-derived quantum-well states, we assert that the interface with the quasiperiodic material constitutes an efficient barrier for electron propagation, due to lack of common point-group symmetries between Bloch-like and critical wave functions. Finally, the depositions of Si and Ge onto the fivefold-symmetry surface of icosahedral

Study of the circular photo-galvanic effect in electrically gated (Bi,Sb)2Te3 thin films

Science.gov (United States)

Pan, Yu; Pillsbury, Timothy; Richardella, Anthony; Flanagan, Thomas; Samarth, Nitin

Illumination with circularly polarized light is known to produce a helicity dependent photocurrent in topological insulators such as Bi2Se3 [Nature Nanotech. 7, 96 (2012)]. Symmetry considerations suggest that this ``circular photo-galvanic effect'' (CPGE) arises purely from the surface. However, whether or not the CPGE is directly related to optical excitations from the helical surface states is still under debate. To clarify the origin of the CPGE, we first compare the helicity dependent photocurrent in intrinsic (Bi,Sb)2Te3 to Cr doped (Bi,Sb)2Te3 thin films in which the Dirac surface states are perturbed by magnetic coupling. Secondly, we discuss the tunable CPGE in electrically gated (Bi,Sb)2Te3 thin films excited by optical excitations at different wavelengths. The dependence on the chemical potential and the photon energy of the excitation unveils the origin of the CPGE. Funded by ONR.

High spin-polarization in ultrathin Co2MnSi/CoPd multilayers

International Nuclear Information System (INIS)

Galanakis, I.

2015-01-01

Half-metallic Co 2 MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co 2 MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co 2 MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices. - Highlights: • Ab-initio study of ultrathin Co 2 MnSi/CoPd multilayers. • Large values of spin-polarization at the Fermi are retained. • Route for novel spintronic/magnetoelectronic devices

Effect of Mn content on structural, optical, opto-thermal and electrical properties of ZnO:Mn sprayed thin films compounds

International Nuclear Information System (INIS)

Mimouni, R.; Kamoun, O.; Yumak, A.; Mhamdi, A.; Boubaker, K.; Petkova, P.; Amlouk, M.

2015-01-01

Highlights: • Proposing an original explanation to the difference between manganese-doped zinc oxide and undoped behavior. • Presenting an original effective electrical and fluorescence-related calculation scheme. • Outlining original AC–DC investigation protocol. - Abstract: Manganese-doped zinc oxide thin films (ZnO:Mn) at different percentages (0–3%) were deposited on glass substrates using a chemical spray technique. The effects of manganese element content on structural, optical, opto-thermal and electrical conductivity of ZnO:Mn thin films were investigated by means of X-ray diffraction, optical measurement, Photoluminescence spectroscopy and impedance spectroscopy. XRD analysis revealed that all films consist of single phase ZnO and were well crystallized in würtzite phase with the crystallites preferentially oriented towards (0 0 2) direction parallel to c-axis. Doping manganese resulted in a slight decrease in the optical band gap energy of the films and a noticeably change in optical constants. The UV peak positions for ZnO:Mn samples slightly red shift to the longer wavelength in comparison with the pure ZnO which can be attributed to the change in the acceptor level induced by the substitutional Mn 2+ and the band-gap narrowing of ZnO with the Mn dopant. We have performed original AC and DC conductivity studies inspired from Jonscher and small polaron models. These studies helped establishing significant correlation between temperature and activation energy and Mn content. From the spectroscopy impedance analysis we investigated the frequency relaxation phenomenon and the circuit equivalent circuit of such thin films. Finally, all results have been discussed, as an objective of the actual work, in terms of the manganese doping concentration

Annealing effect on structural and optical properties of chemical bath deposited MnS thin film

Energy Technology Data Exchange (ETDEWEB)

Ulutas, Cemal, E-mail: cemalulutas@hakkari.edu.tr [Faculty of Education, Hakkari Universty, 30000, Hakkari (Turkey); Gumus, Cebrail [Faculty of Science and Letters, Cukurova University, 01330, Adana (Turkey)

2016-03-25

MnS thin film was prepared by the chemical bath deposition (CBD) method on commercial microscope glass substrate deposited at 30 °C. The as-deposited film was given thermal annealing treatment in air atmosphere at various temperatures (150, 300 and 450 °C) for 1 h. The MnS thin film was characterized by using X-ray diffraction (XRD), UV-vis spectrophotometer and Hall effect measurement system. The effect of annealing temperature on the structural, electrical and optical properties such as optical constants of refractive index (n) and energy band gap (E{sub g}) of the film was determined. XRD measurements reveal that the film is crystallized in the wurtzite phase and changed to tetragonal Mn{sub 3}O{sub 4} phase after being annealed at 300 °C. The energy band gap of film decreased from 3.69 eV to 3.21 eV based on the annealing temperature.

Characterization of nanostructured Mn{sub 3}O{sub 4} thin films grown by SILAR method at room temperature

Energy Technology Data Exchange (ETDEWEB)

Ubale, A.U., E-mail: ashokuu@yahoo.com [Nanostructure Thin Film Materials Laboratory, Department of Physics, Govt. Vidarbha Institute of Science and Humanities, VMV Road, Amravati 444604, Maharashtra (India); Belkhedkar, M.R. [Department of Physics, Shri Shivaji College, Akola 444003, Maharashtra (India); Sakhare, Y.S. [Nanostructure Thin Film Materials Laboratory, Department of Physics, Govt. Vidarbha Institute of Science and Humanities, VMV Road, Amravati 444604, Maharashtra (India); Singh, Arvind [National Centre for Nanomaterials and Nanotechnology, University of Mumbai, Santacruz, Mumbai, Maharashtra (India); Gurada, Chetan; Kothari, D.C. [Department of Physics, University of Mumbai, Santacruz, Mumbai, Maharashtra (India)

2012-10-15

A novel successive ionic layer adsorption and reaction method has been successfully employed to grow nanostructured conducting nearly transparent thin films of Mn{sub 3}O{sub 4} on to glass substrates at room temperature using MnCl{sub 2} and NaOH as cationic and anionic precursors. The structural and morphological characterizations of the as deposited Mn{sub 3}O{sub 4} films have been carried out by means of X-ray diffraction (XRD), Field Emission Scanning Electron Micrograph (FESEM), EDAX, Atomic Fore Microscopy (AFM) and Fourier Transform Infrared Spectrum (FTIR) analysis. The optical absorption and electrical resistivity measurements were carried out to investigate optical band gap and activation energy of Mn{sub 3}O{sub 4} films deposited by SILAR method. The optical band gap and activation energy of the as deposited film is found to be 2.70 and 0.14 eV respectively. The thermo-emf measurements of Mn{sub 3}O{sub 4} thin film confirm its p-type semiconducting nature. Highlights: Black-Right-Pointing-Pointer Nanostructured Mn{sub 3}O{sub 4} thin film is prepared by SILAR method at room temperature. Black-Right-Pointing-Pointer The film is nanocrystalline with orthorhombic structure of Mn{sub 3}O{sub 4}. Black-Right-Pointing-Pointer The XRD, FTIR, FESEM, EDX and AFM characterization confirms nanocrystalline nature. Black-Right-Pointing-Pointer Optical band gap, electrical resistivity and activation energy of film is reported. Black-Right-Pointing-Pointer A thermo-emf measurement confirms p-type conductivity of Mn{sub 3}O{sub 4} films.

Growth and magnetic properties of multiferroic LaxBi1-xMnO3 thin films

Science.gov (United States)

Gajek, M.; Bibes, M.; Wyczisk, F.; Varela, M.; Fontcuberta, J.; Barthélémy, A.

2007-05-01

A comparative study of LaxBi1-xMnO3 thin films grown on SrTiO3 substrates is reported. It is shown that these films grow epitaxially in a narrow pressure-temperature range. A detailed structural and compositional characterization of the films is performed within the growth window. The structure and the magnetization of this system are investigated. We find a clear correlation between the magnetization and the unit-cell volume that we ascribe to Bi deficiency and the resultant introduction of a mixed valence on the Mn ions. On these grounds, we show that the reduced magnetization of LaxBi1-xMnO3 thin films compared to the bulk can be explained quantitatively by a simple model, taking into account the deviation from nominal composition and the Goodenough-Kanamori-Anderson rules of magnetic interactions.

Structural and Electromagnetic Properties of Ni-Mn-Ga Thin Films Deposited on Si Substrates

Directory of Open Access Journals (Sweden)

Pereira M. J.

2014-07-01

Full Text Available Ni2MnGa thin films raise great interest due to their properties, which provide them with strong potential for technological applications. Ni2MnGa thin films were prepared by r.f. sputtering deposition on Si substrates at low temperature (400 ºC. Film thicknesses in the range 10-120 nm were obtained. A study of the structural, magnetic and electrical properties of the films is presented. We find that the deposited films show some degree of crystallinity, with coexisting cubic and tetragonal structural phases, the first one being preponderant over the latter, particularly in the thinner films. The films possess soft magnetic properties and their coercivity is thickness dependent in the range 15-200 Oe at 300K. Electrical resistivity measurements signal the structural transition and suggest the occurrence of avalanche and return-point memory effects, in temperature cycling through the magnetic/structural transition range.

Transport and magnetic properties of Ce-doped LaMnO3 thin films

International Nuclear Information System (INIS)

Yanagida, Takeshi; Kanki, Teruo; Vilquin, Bertrand; Tanaka, Hidekazu; Kawai, Tomoji

2005-01-01

Ce-doped LaMnO 3 epitaxial thin films were fabricated by a pulsed laser deposition method in consideration of thermodynamics. Oxygen- or argon-atmosphere post-annealed films showed a metal-insulator transition and ferromagnetic property, and the transition temperature T c was found to be significantly influenced by the post-annealing conditions at the T c ranging from 200 to 300 K. Moreover, the majority carriers within Ce-doped LaMnO 3 films were identified to be holes from Hall effect measurements

Effect of manganese doping on remnant polarization and leakage current in (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.10,Sb0.06)O3 epitaxial thin films on SrTiO3

Science.gov (United States)

Abazari, M.; Akdoǧan, E. K.; Safari, A.

2008-05-01

Single phase, epitaxial, ⟨001⟩ oriented, undoped and 1mol% Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.10,Sb0.06)O3 thin films of 400nm thickness were synthesized on SrRuO3 coated SrTiO3. Such films exhibit well saturated hysteresis loops and have a spontaneous polarization (Ps) of 10μC /cm2, which is a 150% higher over the Ps of the undoped composition. The coercive field of 1mol% Mn doped films is 13kV/cm. Mn-doping results in three orders of magnitude decrease in leakage current above 50kV/cm electric field, which we attribute to the suppression of intrinsic p-type conductivity of undoped films by Mn donors.

Growth of manganese sulfide (α-MnS) thin films by thermal vacuum evaporation: Structural, morphological and optical properties

Energy Technology Data Exchange (ETDEWEB)

Hannachi, Amira, E-mail: amira.hannachi88@gmail.com [MALTA-Consolider Team, Institut de Ciència dels Materials – Departamento de Fisica Aplicada, University of Valencia, E-46100 Burjassot, Valencia (Spain); Université de Tunis El-Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie Analytique et Electrochimie, LR99ES15, 2092 Tunis (Tunisia); Segura, Alfredo [MALTA-Consolider Team, Institut de Ciència dels Materials – Departamento de Fisica Aplicada, University of Valencia, E-46100 Burjassot, Valencia (Spain); Maghraoui-Meherzi, Hager [Université de Tunis El-Manar, Faculté des Sciences de Tunis, Laboratoire de Chimie Analytique et Electrochimie, LR99ES15, 2092 Tunis (Tunisia)

2016-09-15

MnS thin films have been successfully prepared by thermal evaporation method at different substrate temperatures using different masses of MnS powder. The prepared films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and UV–visible spectrophotometry. The XRD measurements show that the films crystallized in the pure α-MnS for substrate temperatures above 100 °C. The optical bandgap of thin films is found to be in the range of 3.2–3.3 eV. A factorial experimental design was used for determining the influence of the two experimental parameters on the films growth. - Highlights: • α-MnS films were deposited on glass and quartz substrates using the thermal evaporation technique. • The effect of substrate temperature on the properties of the MnS films has been studied. • The factorial design was used to determine the most influence parameters.

Effect of InSb/In0.9Al0.1Sb superlattice buffer layer on the structural and electronic properties of InSb films

Science.gov (United States)

Zhao, Xiaomeng; Zhang, Yang; Guan, Min; Cui, Lijie; Wang, Baoqiang; Zhu, Zhanping; Zeng, Yiping

2017-07-01

The effect of InSb/In0.9Al0.1Sb buffer layers on InSb thin films grown on GaAs (0 0 1) substrate by molecular beam epitaxy (MBE) is investigated. The crystal quality and the surface morphology of InSb are characterized by XRD and AFM. The carrier transport property is researched through variable temperature hall test. The sharp interface between InSb/In0.9Al0.1Sb is demonstrated important for the high quality InSb thin film. We try different superlattice buffer layers by changing ratios, 2-0.5, thickness, 300-450 nm, and periods, 20-50. According to the function of the dislocation density to the absolute temperature below 150 K with different periods of SL buffers, we can find that the number of periods of superlattice is a major factor to decrease the density of threading dislocations. With the 50 periods SL buffer layer, the electron mobility of InSb at the room temperature and liquid nitrogen cooling temperature is ∼63,000 and ∼4600 cm2/V s, respectively. We deduce that the interface in the SL structure works as a filter layer to prevent the dislocation propagating to the upper InSb thin films.

Effect of tungsten on the phase-change properties of Ge_8Sb_2Te_1_1 Thin Films for the Phase-change device

International Nuclear Information System (INIS)

Park, Cheol-Jin; Kong, Heon; Lee, Hyun-Yong; Yeo, Jong-Bin

2017-01-01

In this study, the electrical, optical, and structural properties of tungsten (W)-doped Ge_8Sb_2Te_1_1 thin films were investigated. Previously, GeSbTe alloys were doped with various materials in an attempt to improve the thermal stability. Ge_8Sb_2Te_1_1 and W-doped Ge_8Sb_2Te_1_1 films with a thickness of 200 nm were fabricated by using an RF magnetron reactive co-sputtering system at room temperature on Si (p-type, 100) and glass substrate. The fabricated thin films were annealed in a furnace in the ∼ 0 - 400 ℃ temperature range. The optical properties were analyzed using a UV-Vis-IR spectrophotometer, and by using Beer’s Law equation, the optical-energy band gap (E_o_p), slope B"1"/"2, and slope 1/F were calculated. For the crystalline materials, an increase in the slope B"1"/"2 and 1/F was observed, exhibiting a good effect on the thermal stability in the amorphous state after the phase change. The structural properties were analyzed by X-ray diffraction, and the result showed that the W-doped Ge_8Sb_2Te_1_1 had a face-centered-cubic (fcc) crystalline structure increased crystallization temperature (T_c). An increase in the T_c increased the thermal stability in the amorphous state. The electrical properties were analyzed using a 4-point probe, exhibiting an increase in the sheet resistance (R_s) in the amorphous and the crystalline states indicating a reduced programming current in the memory device.

Electrical properties and transport mechanisms in phase change memory thin films of quasi-binary-line GeTe–Sb{sub 2}Te{sub 3} chalcogenide semiconductors

Energy Technology Data Exchange (ETDEWEB)

Sherchenkov, A. A. [National Research University of Electronic Technology (Russian Federation); Kozyukhin, S. A., E-mail: sergkoz@igic.ras.ru [Russian Academy of Sciences, Kurnakov Institute of General and Inorganic Chemistry (Russian Federation); Lazarenko, P. I.; Babich, A. V. [National Research University of Electronic Technology (Russian Federation); Bogoslovskiy, N. A. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Sagunova, I. V.; Redichev, E. N. [National Research University of Electronic Technology (Russian Federation)

2017-02-15

The temperature dependences of the resistivity and current–voltage (I–V) characteristics of phase change memory thin films based on quasi-binary-line GeTe–Sb{sub 2}Te{sub 3} chalcogenide semiconductors Ge{sub 2}Sb{sub 2}Te{sub 5}, GeSb{sub 2}Te{sub 5}, and GeSb{sub 4}Te{sub 7} are investigated. The effect of composition variation along the quasibinary line on the electrical properties and transport mechanisms of the thin films is studied. The existence of three ranges with different I–V characteristics is established. The position and concentration of energy levels controlling carrier transport are estimated. The results obtained show that the electrical properties of the thin films can significantly change during a shift along the quasi-binary line GeTe–Sb{sub 2}Te{sub 3}, which is important for targeted optimization of the phase change memory technology.

Reversible electrical resistance switching in GeSbTe thin films : An electrolytic approach without amorphous-crystalline phase-change

NARCIS (Netherlands)

Pandian, Ramanathaswamy; Kooi, Bart J.; Palasantzas, George; De Hosson, Jeff Th. M.; Wouters, DJ; Hong, S; Soss, S; Auciello, O

2008-01-01

Besides the well-known resistance switching originating from the amorphous-crystalline phase-change in GeSbTe thin films, we demonstrate another switching mechanism named 'polarity-dependent resistance (PDR) switching'. 'Me electrical resistance of the film switches between a low- and high-state

In situ X-ray diffraction study of crystallization process of GeSbTe thin films during heat treatment

Energy Technology Data Exchange (ETDEWEB)

Kato, Naohiko [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan)]. E-mail: e0957@mosk.tytlabs.co.jp; Konomi, Ichiro [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan); Seno, Yoshiki [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan); Motohiro, Tomoyoshi [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan)

2005-05-15

The crystallization processes of the Ge{sub 2}Sb{sub 2}Te{sub 5} thin film used for PD and DVD-RAM were studied in its realistic optical disk film configurations for the first time by X-ray diffraction using an intense X-ray beam of a synchrotron orbital radiation facility (SPring-8) and in situ quick detection with a Position-Sensitive-Proportional-Counter. The dependence of the amorphous-to-fcc phase-change temperature T{sub 1} on the rate of temperature elevation R{sub et} gave an activation energy E{sub a}: 0.93 eV much less than previously reported 2.2 eV obtained from a model sample 25-45 times thicker than in the real optical disks. The similar measurement on the Ge{sub 4}Sb{sub 1}Te{sub 5} film whose large reflectance change attains the readability by CD-ROM drives gave E{sub a}: 1.13 eV with larger T{sub 1} than Ge{sub 2}Sb{sub 2}Te{sub 5} thin films at any R{sub et} implying a lower sensitivity in erasing as well as a better data stability of the phase-change disk.

Characterization of Cu3SbS3 thin films grown by thermally diffusing Cu2S and Sb2S3 layers

OpenAIRE

Hussain, Arshad; Ahmed, Rashid; Ali, N.; Shaari, A.; Luo, Jing-Ting; Fu, Yong Qing

2017-01-01

Copper antimony sulphide (Cu3SbS3) with a p-type conductivity and optical band gaps in the range of 1.38 to 1.84 eV is considered to be a promising solar harvesting material with non-toxic and economical elements. In this study, we reported the fabrication of Cu3SbS3 thin films using successive thermal evaporation of Cu2S and Sb2S3 layers followed by annealing in an argon atmosphere at a temperature range of 300-375°C. The structural and optical properties of the as-deposited and annealed fil...

Dependence of the constitution, microstructure and electrochemical behaviour of magnetron sputtered Li-Ni-Mn-Co-O thin film cathodes for lithium-ion batteries on the working gas pressure and annealing conditions

International Nuclear Information System (INIS)

Strafela, Marc; Fischer, Julian; Leiste, Harald; Rinke, Monika; Bergfeldt, Thomas; Seifert, Hans Juergen; Ulrich, Sven; Music, Denis; Chang, Keke; Schneider, Jochen

2017-01-01

Li(Ni 1/3 Mn 1/3 Co 1/3 )O 2 as a cathode material for lithium ion batteries shows good thermal stability, high reversible capacity (290 mAh g -1 ), good rate capability and better results in terms of environmental friendliness. In this paper thin film cathodes in the material system Li-Ni-Mn-Co-O were deposited onto silicon and stainless steel substrates, by non-reactive r.f. magnetron sputtering from a ceramic Li 1.18 (Ni 0.39 Mn 0.19 Co 0.35 )O 1.97 target at various argon working gas pressures between 0.2 Pa and 20 Pa. A comprehensive study on the composition and microstructure was carried out. The results showed that the elemental composition varies depending on argon working gas pressure. The elemental composition was determined by inductively coupled plasma optical emission spectroscopy in combination with carrier gas hot extraction. The films showed different grain orientations depending argon working gas pressures. The degree of cation order in the lattice structure of the films deposited at 0.5 Pa and 7 Pa argon working gas pressure, was increased by annealing in an argon/oxygen atmosphere at different pressures for one hour. The microstructure of the films varies with annealing gas pressure and is characterized using X-ray diffraction and unpolarized micro-Raman spectroscopy at room temperature. Electrochemical characterization of as-deposited and annealed films was carried out by galvanostatic cycling in Li-Ni-Mn-Co-O half-cells against metallic lithium. Correlations between process parameters, constitution, microstructure and electrochemical behaviour are discussed in detail.

MnSi nanostructures obtained from epitaxially grown thin films: magnetotransport and Hall effect

Science.gov (United States)

Schroeter, D.; Steinki, N.; Schilling, M.; Fernández Scarioni, A.; Krzysteczko, P.; Dziomba, T.; Schumacher, H. W.; Menzel, D.; Süllow, S.

2018-06-01

We present a comparative study of the (magneto)transport properties, including Hall effect, of bulk, epitaxially grown thin film and nanostructured MnSi. In order to set our results in relation to published data we extensively characterize our materials, this way establishing a comparatively good sample quality. Our analysis reveals that in particular for thin film and nanostructured material, there are extrinsic and intrinsic contributions to the electronic transport properties, which by modeling the data we separate out. Finally, we discuss our Hall effect data of nanostructured MnSi under consideration of the extrinsic contributions and with respect to the question of the detection of a topological Hall effect in a skyrmionic lattice.

Resistive switching properties of Ce and Mn co-doped BiFeO{sub 3} thin films for nonvolatile memory application

Energy Technology Data Exchange (ETDEWEB)

Tang, Zhenhua; Zeng, Jia; Tang, Minghua, E-mail: mhtang@xtu.edu.cn; Xu, Dinglin; Cheng, Chuanpin; Xiao, Yongguang; Zhou, Yichun [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan, Hunan, 411105 (China); Xiong, Ying [The School of Mathematics and Computational Science, Xiangtan University, Xiangtan, Hunan 411105 (China)

2013-12-15

The Ce and Mn co-doped BiFeO{sub 3} (BCFMO) thin films were synthesized on Pt/Ti/SiO{sub 2}/Si substrates using a sol-gel method. The unipolar resistive switching (URS) and bipolar resistive switching (BRS) behaviors were observed in the Pt/BCFMO/Pt device structure, which was attributed to the formation/rupture of metal filaments. The fabricated device exhibits a large R{sub OFF}/R{sub ON} ratio (>80), long retention time (>10{sup 5} s) and low programming voltages (<1.5 V). Analysis of linear fitting current-voltage curves suggests that the space charge limited leakage current (SCLC) and Schottky emission were observed as the conduction mechanisms of the devices.

Evidence for surface-generated photocurrent in (Bi,Sb)2Se3and(Bi,Sb)2Te3 thin films

Science.gov (United States)

Pan, Yu; Richardella, Anthony; Yao, Bing; Lee, Joon Sue; Flanagan, Thomas; Kandala, Abhinav; Samarth, Nitin; Yeats, Andrew; Mintun, Peter; Awschalom, David

2015-03-01

Illumination with circularly polarized light is known produce a helicity-dependent photocurrent in topological insulators such as Bi2Se3 [e.g. Nature Nanotech. 7, 96 (2012)]. However, the exact origin of this effect is still unclear since it is observed with photons well above the bulk band gap. We report measurements of the polarization-dependent photocurrent in a series of (Bi,Sb)2Se3 thin films with different carrier concentrations and find that the photocurrent is enhanced as we increase the population of the surface states. This finding is supported by a study of helicity-dependent photocurrents in back-gated (Bi,Sb)2Te3 thin films, where the chemical potential is varied electrostatically. By illuminating our samples at different wavelengths, we show that the helicity-dependent photocurrent is enhanced when the photon energy approaches the energy difference between the lowest and first excited (unoccupied) topological surface states. This leads us to attribute the helicity-dependent photocurrent in topological insulators to optical excitations between these two spin-textured surface states. We will also discuss experiments imaging the spatial variation of these helicity-dependent photocurrents. This work is supported by ONR.

Room temperature magnetocaloric effect in Ni-Mn-In-Cr ferromagnetic shape memory alloy thin films

Energy Technology Data Exchange (ETDEWEB)

Akkera, Harish Sharma [Functionalnanomaterials Research Lab, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand-247667 (India); Singh, Inderdeep [Mechanical and Industrial Engineering Department, Indian Institute of Technology Roorkee, Uttarakhand-24667 (India); Kaur, Davinder, E-mail: dkaurfph@iitr.ernet.in [Functionalnanomaterials Research Lab, Department of Physics, Indian Institute of Technology Roorkee, Uttarakhand-247667 (India)

2017-02-15

The influence of Cr substitution for In on the martensitic phase transformation and magnetocaloric effect (MCE) has been investigated in Ni-Mn-Cr-In ferromagnetic shape memory alloy (FSMA) thin films fabricated by magnetron sputtering. Temperature dependent magnetization (M-T) measurements demonstrated that the martensitic transformation temperatures (T{sub M}) monotonously increase with the increase of Cr content due to change in valence electron concentration (e/a) and cell volume. From the study of isothermal magnetization curves (M-H), magnetocaloric effect around the martensitic transformation has been investigated in these FSMA thin films. The magnetic entropy change ∆S{sub M} of 7.0 mJ/cm{sup 3}-K was observed in Ni{sub 51.1}Mn{sub 34.9}In{sub 9.5}Cr{sub 4.5} film at 302 K in an applied field of 2 T. Further, the refrigerant capacity (RC) was also calculated for all the films in an applied field of 2 T. These findings indicate that the Cr doped Ni-Mn-In FSMA thin films are potential candidates for room temperature micro-length-scale magnetic refrigeration applications. - Highlights: • The Cr content leads to an increase in the martensitic transformation temperature. • The ∆S{sub M} =7 mJ/cm{sup 3}-K at 302 K was observed in the Ni{sub 51.1}Mn{sub 34.9}In{sub 9.5}Cr{sub 4.5}. • The RC =39.2 mJ/K at 2 T was obtained in Ni{sub 51.1}Mn{sub 34.9}In{sub 9.5}Cr{sub 4.5} film.

Spin injection from epitaxial Heusler alloy thin films into InGaAs/GaAs quantum wells

DEFF Research Database (Denmark)

Damsgaard, Christian Danvad

2006-01-01

-stoichiometric crystals and crystals with site swapping defects. Significant decrease in the spin polarization has been predicted for disorder defects involving especially Co on Mn or Ga sites. From an estimate based on the calculated defect formation energies it is found that Mn on Co-sites are likely to exist...... no anisotropy is seen for near stoichiometry thin films on an ordinary GaAs surface. Typically thin films grown on GaAs show lower saturation magnetization than expected from bulk properties. The electrical characterizations have revealed resistivities around ρ = 350μΩcm at 300 K. Generally, the near...... to typically 0.02-0.1 Ωmm2 for Fe and Co contacts but two orders of magnitude higher for the Co2MnGa contacts. Point contact Andreev reflection measurements on an off-stoichiometric thin film (Co2.4Mn1.6Ga) show a spin polarization of P ≈ 50 %. Furthermore spin injection into a InGaAs/GaAs quantum well have...

Superconducting thin films of As-free pnictide LaPd{sub 1-x}Sb{sub 2} grown by reactive molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Retzlaff, Reiner; Buckow, Alexander; Kurian, Jose; Alff, Lambert [Institute of Materials Science, Technische Universitaet Darmstadt, Petersenstr. 23, 64287 Darmstadt (Germany)

2013-07-01

We use reactive molecular beam epitaxy as synthesis technique for the search of arsenic free pnictide superconductors. Epitaxial thin films of LaPd{sub 1-x}Sb{sub 2} were grown on (100) MgO substrates from elemental sources by simultaneous evaporation of high purity La, Pd and Sb metals by e-gun. LaPd{sub 1-x}Sb{sub 2} belongs to a novel class of pnictide superconductors with a peculiar pnictide square net layer. Previously, we have reported epitaxial growth of isostructural Bi based compounds. The substitution of Bi by Sb leads to thin films with metallic behavior and room temperature resistivity of about 85 μΩ cm. The highest observed transition temperature T{sub c} inLaPd{sub 1-x}Sb{sub 2} is 3.1 K and does not depend on x. We discuss strategies to increase T{sub c} in this pnictide subfamily.

Magnetic and magneto-optical characteristics of spin coated Co{sub 0.6}Zn{sub 0.4}Fe{sub 1.7}Mn{sub 0.3}O{sub 4} thin films on Pt (1 1 1) coated Si substrate

Energy Technology Data Exchange (ETDEWEB)

Gupta, Arti, E-mail: artigupta80@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi110007 (India); Dutta, Shankar [Solid State Physics Laboratory, DRDO, Lucknow Road, Timarpur, Delhi110054 (India); Tandon, Ram Pal [Department of Physics and Astrophysics, University of Delhi, Delhi110007 (India)

2016-05-15

Highlights: • Properties of Co{sub 0.6}Zn{sub 0.4}Mn{sub 0.3}Fe{sub 1.7}O{sub 4} thin films on Pt-Si substrate are reported. • Reduction in thickness ∼27% with increased annealing temperature was found. • Partial (3 3 3) plane textured orientation was noted for these films. - Abstract: This paper reports magnetic and magneto-optical properties of Co{sub 0.6}Zn{sub 0.4}Fe{sub 1.7}Mn{sub 0.3}O{sub 4} nanocrystalline thin films (thickness ∼140–200 nm) deposited on Pt (1 1 1)/Ti/SiO{sub 2}/Si substrates by spin coating technique. Deposited films are then annealed at 600 °C and 700 °C for 60 min (significant reduction in film thickness from 200 nm to 140 nm was noted with the increase in post deposition annealing temperature). The X ray diffraction patterns confirmed the spinel cubic structure of Co{sub 0.6}Zn{sub 0.4}Fe{sub 1.7}Mn{sub 0.3}O{sub 4} films with polycrystalline phase and also indicated a partial <3 3 3> texture orientation. Deposited films showed magnetic anisotropy as evidenced from magnetic and magneto-optical measurements. Higher in plane remnant magnetization and low coercivity values as compared to out of plane ones were observed for both samples, indicating in plane alignment of easy axis of magnetization.

Preparation and characterization of TiO[sub 2]/Sb thin films for solar energy applications

Energy Technology Data Exchange (ETDEWEB)

Badawy, W.A. (Dept. of Chemistry, Cairo Univ., Giza (Egypt))

1993-01-01

Pure and antimony-incorporated TiO[sub 2] thin films were prepared using a spray-CVD method. The method allows for convenient incorporation of foreign atoms into the oxide matrix during film growth. The foreign atoms in the oxide film affects both the photovoltaic and photoelectrochemical properties of the n-Si/oxide heterojunction. The characteristics of the prepared oxide films were affected significantly by the presence of antimony on the oxide matrix. The increased conductivity of the Sb-containing oxide layers is reflected in the improved photovoltaic properties of the prepared n-Si/TiO[sub 2]-Sb heterojunctions, e.g. fill factor and solar conversion efficiency. The photoelectrochemical properties of the prepared devices revealed that the charge transfer step at the oxide/electrolyte interface leads to a deterioration of the cell quality. However, this drawback has been offset by the improved properties of the heterojunction. (orig.)

Tuning of Transport and Magnetic Properties in Epitaxial LaMnO3+δ Thin Films

Directory of Open Access Journals (Sweden)

J. Chen

2014-01-01

Full Text Available The effect of compressive strain on the transport and magnetic properties of epitaxial LaMnO3+δ thin films has been investigated. It is found that the transport and magnetic properties of the LaMnO3+δ thin films grown on the LaAlO3 substrates can be tuned by the compressive strain through varying film thickness. And the insulator-metal transition, charge/orbital ordering transition, and paramagnetic-ferromagnetic transition are suppressed by the compressive strain. Consequently, the related electronic and magnetic transition temperatures decrease with an increase in the compressive strain. The present results can be explained by the strain-controlled lattice deformation and the consequent orbital occupation. It indicates that the lattice degree of freedom is crucial for understanding the transport and magnetic properties of the strongly correlated LaMnO3+δ.

Influence of the oxygen pressure on the preferred orientation and optical properties of the pulsed-laser deposited Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4±δ} thin films

Energy Technology Data Exchange (ETDEWEB)

Kong, Wenwen [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Gao, Bo [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Jiang, Chunping, E-mail: cpjiang2008@sinano.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics of CAS, Suzhou 215123 (China); Chang, Aimin, E-mail: changam@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China)

2015-11-25

Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4±δ} (MCN) thin films with different oxygen pressures (in the range of 2 × 10{sup −4} to 2 Pa) are prepared on Si(100)/SiO{sub x} substrates by pulsed laser deposition technique. Effects of oxygen pressures on the microstructure and optical properties of the prepared thin films are investigated in detail. The grain sizes of films gradually decrease and the preferential orientation of the MCN films change from (400) to (113) as the oxygen pressure increases. The x-ray photoelectron spectroscopy results show that the composition of these films is proximity to that of the bulk material. In addition, the Mn{sup 3+}/Mn{sup 4+} pairs increase with an increase in the oxygen pressures increase. From spectroscopic ellipsometer spectroscopy, it is found that both the refractive index n and extinction coefficient k of the (400)-oriented films have no obvious peaks, whereas in the (113)-oriented films, peaks are exist. This feature typically originates from a change in the crystal structure as oxygen pressures increase. Furthermore, the Raman active mode (around ca. 650 cm{sup −1}) of (400) films almost disappears, whilst the active mode in (113) films remain. - Highlights: • The Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4-δ} (MCN) spinel films are deposited by pulsed laser deposition process at different oxygen pressures. • The preferential orientation of the films changes from (400) plane to (113) as the oxygen pressure increases. • The E{sub g} of the (113) film is twice as large as that of the (400) film. • The Raman active mode (around ca. 650 cm{sup −1}) can be observed in the (113) films while not in the (400) film.

Magnetic domains in Ni-Mn-Ga martensitic thin films

International Nuclear Information System (INIS)

Chernenko, V A; Anton, R Lopez; Kohl, M; Ohtsuka, M; Orue, I; Barandiaran, J M

2005-01-01

A series of martensitic Ni 52 Mn 24 Ga 24 thin films deposited on alumina ceramic substrates has been prepared by using RF(radio-frequency) magnetron sputtering. The film thickness, d, varies from 0.1 to 5.0m. Magnetic domain patterns have been imaged by the MFM (magnetic force microscopy) technique. A maze domain structure is found for all studied films. MFM shows a large out-of-plane magnetization component and a rather uniform domain width for each film thickness. The domain width, δ, depends on the film thickness as δ∝√d in the whole studied range of film thickness. This dependence is the expected one for magnetic anisotropy and magnetostatic contributions in a perpendicular magnetic domain configuration. The proportionality coefficient is also consistent with the values of saturation magnetization and magnetic anisotropy determined in the samples

Study on the application of magnesium oxide adsorptive compound to preconcentrate trace elements (As, Cu, Co, Cr, Hg, Mn, Sb and Zn) in high salt water and neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Giang, Nguyen; Tam, Nguyen Thanh; Phuong Mai, Truong Thi; Ho Tran The Huu [Center for Analytical Techniques, Nuclear Research Institute, Dalat (Viet Nam)

2007-12-15

The project presents preconcentration neutron activation analysis techniques for determination of trace metals (As, Co, Cr Cu, Hg, Mn, Sb and Zn) in high salt water by adsorption of trace metals on magnesium oxide. Precipitate is collected on 0.45 {mu}m membrane filters and irradiated in pneumatic rabit system and Lazy Susan facility at flux 5.10{sup 12} n/cm{sup 2}.sec for As, Cu, Mn and 2.10{sup 12} n/cm{sup 2}.sec for Hg, Sb, Cr, Co and Zn. The radioactivities of {sup 76}As, {sup 60}Co, {sup 64}Cu, {sup 51}Cr, {sup 203}Hg, {sup 56}Mn, {sup 124}Sb and {sup 65}Zn were measured. {sup 76}As, {sup 60}Co, {sup 64}Cu, {sup 51}Cr, {sup 203}Hg, {sup 56}Mn, {sup 124}Sb and {sup 65}Zn radio traces were used to establish optimum conditions and to evaluate the chemical yield. Detection limits of this method are 0.019, 0.006, 0.044, 0.058, 0.021, 0.027, 0.012 and 0.094 {mu}g of As, Co, Cr, Cu, Hg, Mn, Sb and Zn respectively. (author)

Analysis of multiferroic properties in BiMnO3 thin films

International Nuclear Information System (INIS)

Grizalez, M; Mendoza, G A; Prieto, P

2009-01-01

Textured BiMnO 3 [111] thin films on SrTiO 3 (100) and Pt/TiO 2 /SiO 2 substrates were grown via r.f. magnetron sputtering (13.56 MHz). The XRD spectra confirmed a monoclinic structure and high-quality textured films for the BiMnO 3 films. The films grown on SrTiO 3 (100) showed higher crystalline quality than those developed on Pt/TiO 2 /SiO 2 . Through optimized oxygen pressure of 5x10 -2 mbar during the r.f. sputtering deposition, the crystalline orientation of the BiMnO 3 film was improved with respect to the previously reported value of 2x10 -1 mbar. The values of spontaneous polarization (P s ), remnant polarization (P r ), and coercive field (F c ) from ferroelectric hysteresis loops (P-E) at different temperatures were also obtained. Samples with higher crystalline order revealed better dielectric properties (high P s and P r values and a low F c ). For films on both types of substrates, the ferroelectric behavior was found to persist up to 400K. Measurements at higher temperatures were difficult to obtain given the increased conductivity of the films. Magnetic hysteresis loops from 5K to 120K were obtained for BiMnO 3 films grown on SrTiO 3 and Pt/TiO 2 /SiO 2 substrates. The results suggested that the coexistence of the magnetic and electric phases persists up to 120K.

High spin-polarization in ultrathin Co{sub 2}MnSi/CoPd multilayers

Energy Technology Data Exchange (ETDEWEB)

Galanakis, I., E-mail: galanakis@upatras.gr

2015-03-01

Half-metallic Co{sub 2}MnSi finds a broad spectrum of applications in spintronic devices either in the form of thin films or as spacer in multilayers. Using state-of-the-art ab-initio electronic structure calculations we exploit the electronic and magnetic properties of ultrathin Co{sub 2}MnSi/CoPd multilayers. We show that these heterostructures combine high values of spin-polarization at the Co{sub 2}MnSi spacer with the perpendicular magnetic anisotropy of binary compounds such as CoPd. Thus they could find application in spintronic/magnetoelectronic devices. - Highlights: • Ab-initio study of ultrathin Co{sub 2}MnSi/CoPd multilayers. • Large values of spin-polarization at the Fermi are retained. • Route for novel spintronic/magnetoelectronic devices.

Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films

Energy Technology Data Exchange (ETDEWEB)

Abazari, M; Safari, A [Glenn Howatt Electroceramics Laboratories, Department of Materials Science and Engineering, Rutgers-The state University of New Jersey, Piscataway, NJ 08854 (United States); Choi, T; Cheong, S-W [Rutgers Center for Emergent Materials, Department of Physics and Astronomy, Rutgers-The state University of New Jersey, Piscataway, NJ 08854 (United States)

2010-01-20

We report the observation of domain structure and piezoelectric properties of pure and Mn-doped (K{sub 0.44},Na{sub 0.52},Li{sub 0.04})(Nb{sub 0.84},Ta{sub 0.1},Sb{sub 0.06})O{sub 3} (KNN-LT-LS) thin films on SrTiO{sub 3} substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180{sup 0} domains. This was in accordance with the tetragonal structure of the films, confirmed by relative permittivity measurements and x-ray diffraction patterns. Effective piezoelectric coefficient (d{sub 33}) of the films were calculated using piezoelectric displacement curves and shown to be {approx}53 pm V{sup -1} for pure KNN-LT-LS thin films. This value is among the highest values reported for an epitaxial lead-free thin film and shows a great potential for KNN-LT-LS to serve as an alternative to PZT thin films in future applications.

Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films

Science.gov (United States)

Abazari, M.; Choi, T.; Cheong, S.-W.; Safari, A.

2010-01-01

We report the observation of domain structure and piezoelectric properties of pure and Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180° domains. This was in accordance with the tetragonal structure of the films, confirmed by relative permittivity measurements and x-ray diffraction patterns. Effective piezoelectric coefficient (d33) of the films were calculated using piezoelectric displacement curves and shown to be ~53 pm V-1 for pure KNN-LT-LS thin films. This value is among the highest values reported for an epitaxial lead-free thin film and shows a great potential for KNN-LT-LS to serve as an alternative to PZT thin films in future applications.

Dependence of the constitution, microstructure and electrochemical behaviour of magnetron sputtered Li-Ni-Mn-Co-O thin film cathodes for lithium-ion batteries on the working gas pressure and annealing conditions

Energy Technology Data Exchange (ETDEWEB)

Strafela, Marc; Fischer, Julian; Leiste, Harald; Rinke, Monika; Bergfeldt, Thomas; Seifert, Hans Juergen; Ulrich, Sven [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Applied Materials (IAM); Music, Denis; Chang, Keke; Schneider, Jochen [RWTH Aachen Univ. (Germany). Materials Chemistry

2017-11-15

Li(Ni{sub 1/3}Mn{sub 1/3}Co{sub 1/3})O{sub 2} as a cathode material for lithium ion batteries shows good thermal stability, high reversible capacity (290 mAh g{sup -1}), good rate capability and better results in terms of environmental friendliness. In this paper thin film cathodes in the material system Li-Ni-Mn-Co-O were deposited onto silicon and stainless steel substrates, by non-reactive r.f. magnetron sputtering from a ceramic Li{sub 1.18}(Ni{sub 0.39}Mn{sub 0.19}Co{sub 0.35})O{sub 1.97} target at various argon working gas pressures between 0.2 Pa and 20 Pa. A comprehensive study on the composition and microstructure was carried out. The results showed that the elemental composition varies depending on argon working gas pressure. The elemental composition was determined by inductively coupled plasma optical emission spectroscopy in combination with carrier gas hot extraction. The films showed different grain orientations depending argon working gas pressures. The degree of cation order in the lattice structure of the films deposited at 0.5 Pa and 7 Pa argon working gas pressure, was increased by annealing in an argon/oxygen atmosphere at different pressures for one hour. The microstructure of the films varies with annealing gas pressure and is characterized using X-ray diffraction and unpolarized micro-Raman spectroscopy at room temperature. Electrochemical characterization of as-deposited and annealed films was carried out by galvanostatic cycling in Li-Ni-Mn-Co-O half-cells against metallic lithium. Correlations between process parameters, constitution, microstructure and electrochemical behaviour are discussed in detail.

Sb-related defects in Sb-doped ZnO thin film grown by pulsed laser deposition

Science.gov (United States)

Luo, Caiqin; Ho, Lok-Ping; Azad, Fahad; Anwand, Wolfgang; Butterling, Maik; Wagner, Andreas; Kuznetsov, Andrej; Zhu, Hai; Su, Shichen; Ling, Francis Chi-Chung

2018-04-01

Sb-doped ZnO films were fabricated on c-plane sapphire using the pulsed laser deposition method and characterized by Hall effect measurement, X-ray photoelectron spectroscopy, X-ray diffraction, photoluminescence, and positron annihilation spectroscopy. Systematic studies on the growth conditions with different Sb composition, oxygen pressure, and post-growth annealing were conducted. If the Sb doping concentration is lower than the threshold ˜8 × 1020 cm-3, the as-grown films grown with an appropriate oxygen pressure could be n˜4 × 1020 cm-3. The shallow donor was attributed to the SbZn related defect. Annealing these samples led to the formation of the SbZn-2VZn shallow acceptor which subsequently compensated for the free carrier. For samples with Sb concentration exceeding the threshold, the yielded as-grown samples were highly resistive. X-ray diffraction results showed that the Sb dopant occupied the O site rather than the Zn site as the Sb doping exceeded the threshold, whereas the SbO related deep acceptor was responsible for the high resistivity of the samples.

Gracing incidence small angle neutron scattering of incommensurate magnetic structures in MnSi thin films

Energy Technology Data Exchange (ETDEWEB)

Wiedemann, Birgit; Pfleiderer, Christian; Boeni, Peter [Physik Department, Technische Universitaet Muenchen (Germany); Zhang, Shilei; Hesjedal, Thorsten [Clarendon Laboratory, Department of Physics, University of Oxford (United Kingdom); Khaydukov, Yury; Soltwedel, Olaf; Keller, Thomas [Max-Planck-Institut fuer Festkoerperforschung (Germany); Max Planck Society, Outstation at FRM-II (Germany); Muehlbauer, Sebastian [Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany); Chacon, Alfonso [Physik Department, Technische Universitaet Muenchen (Germany); Forschungsneutronenquelle Heinz Maier Leibnitz, Technische Universitaet Muenchen (Germany)

2015-07-01

The topological stability of skyrmions in bulk samples of MnSi and the observation of spin transfer torque effects at ultra-low current densities have generated great interest in skyrmions in chiral magnets as a new route towards next generation spintronics devices. Yet, the formation of skyrmions in MBE grown thin films of MnSi reported in the literature is highly controversial. We report gracing incidence small angle neutron scattering (GISANS) of the magnetic order in selected thin films of MnSi grown by state of the art MBE techniques. In combination with polarised neutron reflectometry (PNR) and magnetisation measurements of the same samples our data provide direct reciprocal space information of the incommensurate magnetic order, clarifying the nature of magnetic phase diagram.

Phase transformation in Mg—Sb3Te thin films

International Nuclear Information System (INIS)

Li Jun-Jian; Chen Yi-Min; Nie Qiu-Hua; Lü Ye-Gang; Wang Guo-Xiang; Shen Xiang; Dai Shi-Xun; Xu Tie-Feng

2014-01-01

Mg-doped Sb 3 Te films are proposed to improve the performance of phase-change memory (PCM). We prepare Mg-doped Sb 3 Te films and investigate their crystallization behaviors, structural, optical and electrical properties. We find that Mg-doping can increase the crystallization temperature, enhance the activation energy, and improve the 10-year data retention of Sb 3 Te. Especially Mg 25.19 (Sb 3 Te)74.81 shows higher T c (∼ 190 °C) and larger E a (∼ 3.49 eV), which results in a better data retention maintaining for 10 yr at ∼ 112 °C. Moreover R a /R c value is also improved. These excellent properties make Mg—Sb—Te material a promising candidate for the phase-change memory (PCM). (special topic — international conference on nanoscience and technology, china 2013)

Onset of magnetic interface exchange interactions in epitaxially grown Mn-Co(001)

NARCIS (Netherlands)

Kohlhepp, J.T.; Wieldraaijer, H.; Jonge, de W.J.M.

2007-01-01

Manganese (Mn) grows in a metastable expanded (c/a > 1) face-centered-tetragonal (fct) phase on thin fct-Co(001) template films. A layer-by-layer growth mode is obsd. for small Mn thicknesses. Antiferromagnetism (AFM) of fct-Mn is evidenced by the observation of shifted magnetization loops

Thermochromic effect at room temperature of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Boileau, A.; Capon, F.; Barrat, S.; Pierson, J. F. [Universite de Lorraine, Institut Jean Lamour, Departement CP2S, UMR CNRS 7198, Nancy, F-54042 (France); Laffez, P. [Groupe de Recherche Electronique, Materiaux, Acoustique, Nanoscience (GREMAN), Universite Francois Rabelais de Tours, UMR CNRS 7347, IUT de Blois, 15 rue de la Chocolaterie, Blois, F-41000 (France)

2012-06-01

Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3} thermochromic thin films were synthesized using dc reactive magnetron co-sputtering and subsequent annealing in air. The film structure was studied by x-ray diffraction analysis. To validate the thermochromic potentiality of Sm{sub 0.5}Ca{sub 0.5}MnO{sub 3}, electrical resistivity and infrared transmittance spectra were recorded for temperatures ranging from 77 K to 420 K. The temperature dependence of the optical band gap was estimated in the near infrared range. Upon heating, the optical transmission decreases in the infrared domain showing a thermochromic effect over a wide wavelength range at room temperature.

Control of the magnetic properties of LaMnO3 epitaxial thin films grown by Pulsed Laser Deposition

Science.gov (United States)

Martinez, Benjamin; Roqueta, Jaume; Pomar, Alberto; Balcells, Lluis; Frontera, Carlos; Konstantinovic, Zorica; Sandiumenge, Felip; Santiso, Jose; Advanced materials characterization Team; Thin films growth Team

2015-03-01

LaMnO3 (LMO), the parent compound of colossal magnetoresistance based manganites has gained renewed attention as a building block in heterostructures with unexpected properties. In its bulk phase, stoichiometric LMO is an A-type antiferromagnetic (AFM) insulator (TN = 140K) with orthorhombic structure that easily accommodate an oxygen excess by generating cationic (La or Mn) vacancies. As a result, a fraction of Mn 3+ changes to Mn 4+ leading to a double-exchange mediated ferromagnetic (FM) behavior. In thin films the AFM phase has been elusive up to now and thin films with FM ordering are usually reported. In this work, we have systematically studied the growth process of LaMnO3 thin films by pulsed laser deposition on SrTiO3 (001) substrates under different oxygen partial pressures (PO2) . A close correlation between the structure (explored by XRD) and the magnetic properties (SQUID measurements) of the films with PO2 has been identified. At high PO2 FM behavior is observed. In contrast, at very low PO2, the results obtained for unit cell volume (close to stoichiometric bulk values) and magnetic moment (0.2 μB/Mn) strongly indicate antiferromagnetic ordering. We acknowledge financial support from the Spanish MINECO (MAT2012-33207).

Metallic transport and large anomalous Hall effect at room temperature in ferrimagnetic Mn4N epitaxial thin film

International Nuclear Information System (INIS)

Shen, Xi; Shigematsu, Kei; Chikamatsu, Akira; Fukumura, Tomoteru; Hirose, Yasushi; Hasegawa, Tetsuya

2014-01-01

We report the electrical transport properties of ferrimagnetic Mn 4 N (001) epitaxial thin films grown by pulsed laser deposition on MgO (001) substrates. The Mn 4 N thin films were tetragonally distorted with a ratio of out-of-plane to in-plane lattice constants of 0.987 and showed perpendicular magnetic anisotropy with an effective magnetic anisotropy constant of 0.16 MJ/m 3 , which is comparable with that of a recently reported molecular-beam-epitaxy-grown film. The thin films exhibited metallic transport with a room temperature resistivity of 125 μΩ cm in addition to a large anomalous Hall effect with a Hall angle tangent of 0.023.

Effect of post-annealing on the magnetic properties of sputtered Mn56Al44 thin films

Science.gov (United States)

Gupta, Nanhe Kumar; Husain, Sajid; Barwal, Vineet; Behera, Nilamani; Chaudhary, Sujeet

2018-05-01

Mn56Al44 (MnAl) thin films of constant thickness (˜30nm) were grown on naturally oxidized Si substrates using DC-magnetron sputtering. Effect of deposition parameters such as sputtering power, substrate temperature (Ts), and post-annealing temperature have been systematically invstigated. X-ray diffraction patterns revealed the presence of mixed phases, namely the τ- and β-MnAl. The highest saturation magnetization (MS) was found to be 65emu/cc using PPMS-VSM in film grown at Ts=500°C. The magnetic ordering was found to get significantly improved by performing post-annealing of these as-grwon at 400°C for 1 hr in the presence of out-of-plane magnetic field of ˜1500Oe in vacuum. In particular, at room temperature (RT), the MS got enhanced after magnetic annealing from 65emu/cc to 500 emu/cc in MnAl films grown at Ts=500°C. This sample exhibited a magneto-resistance of ˜1.5% at RT. The tuning of the structural and magnetic properties of MnAl binary alloy thin films as established here by varying the growth parameters is critical with regards to the prospective applications of MnAl, a metastable ferromagnetic system which possesses the highest perpendicular magnetic anisotropy at RT till date.

Study of structural and morphological properties of thermally evaporated Sn{sub 2}Sb{sub 6}S{sub 11} thin films

Energy Technology Data Exchange (ETDEWEB)

Ben Mehrez, N., E-mail: najia.benmehrez@gmail.com [Université Tunis El Manar, Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, ENIT, BP 37, Le belvédère, 1002 Tunis (Tunisia); Khemiri, N. [Université Tunis El Manar, Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, ENIT, BP 37, Le belvédère, 1002 Tunis (Tunisia); Kanzari, M. [Université Tunis El Manar, Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, ENIT, BP 37, Le belvédère, 1002 Tunis (Tunisia); Institut Préparatoire aux Etudes d’Ingénieurs de Tunis Montfleury, Université de Tunis (Tunisia)

2016-10-01

In this study, we report the structural and morphological properties of the new material Sn{sub 2}Sb{sub 6}S{sub 11} thin films prepared on glass substrates by vacuum thermal evaporation at various substrate temperatures (30, 60, 100, 140, 180 and 200 °C). Sn{sub 2}Sb{sub 6}S{sub 11} ingot was synthesized by the horizontal Bridgman technique. The structural properties of Sn{sub 2}Sb{sub 6}S{sub 11} powder were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The films were characterized for their structural properties by using XRD. All films were polycrystalline in nature. The variations of the structural parameters of the films with the substrate temperature were investigated. The results show that the crystallite sizes increase as the substrate temperature increases. The morphological properties of the films were analyzed by atomic force microscopy (AFM). The roughness and the topography of the surface of the films strongly depend on the substrate temperature. - Highlights: • Sn{sub 2}Sb{sub 6}S{sub 11} powder was successfully synthesized by the horizontal Bridgman technique. • Sn{sub 2}Sb{sub 6}S{sub 11} films were grown by thermal evaporation at different substrate temperatures. • Structural properties of Sn{sub 2}Sb{sub 6}S{sub 11} powder were investigated. • The effect of the substrate temperature on structural and morphological of Sn{sub 2}Sb{sub 6}S{sub 11} films properties was studied.

Thermoelectric power of Bi and Bi{sub 1{minus}x}Sb{sub x} alloy thin films and superlattices grown by MBE

Energy Technology Data Exchange (ETDEWEB)

Cho, S; DiVenere, A; Wong, G K; Ketterson, J B; Meyer, J R; Hoffman, C A

1997-07-01

The authors have measured the thermoelectric power (TEP) of MBE-grown epitaxial Bi and Bi{sub 1{minus}x} alloy thin films and superlattices as a function of temperature in the range 20--300 K. They have observed that the TEP of a Bi thin film of 1 {micro}m thickness is in good agreement with the bulk single crystal value and that the TEPs for superlattices with 400 {angstrom} and 800 {angstrom} Bi well thicknesses are enhanced over the bulk values. For x = 0.072 and 0.088 in Bi{sub 1{minus}x}Sb{sub x} thin films showing semiconducting behavior, TEP enhancement was observed by a factor of two. However as Bi or Bi{sub 1{minus}x}Sb{sub x} well thickness decreases in superlattice geometry, the TEP decreases, which may be due to unintentional p-type doping.

A novel chemical synthesis and characterization of Mn{sub 3}O{sub 4} thin films for supercapacitor application

Energy Technology Data Exchange (ETDEWEB)

Dubal, D.P.; Dhawale, D.S.; Salunkhe, R.R. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S) (India); Pawar, S.M. [Photonic and Electronic Thin Film Laboratory, Department of Materials Science and Engineering, Chonnam National University, 300 Yongbong-Dong, Puk-Gu, Gwangju 500-757 (Korea, Republic of); Lokhande, C.D., E-mail: l_chandrakant@yahoo.com [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (M.S) (India)

2010-05-01

Mn{sub 3}O{sub 4} thin films have been prepared by novel chemical successive ionic layer adsorption and reaction (SILAR) method. Further these films were characterized for their structural, morphological and optical properties by means of X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), field emission scanning electron microscopy (FESEM), wettability test and optical absorption studies. The XRD pattern showed that the Mn{sub 3}O{sub 4} films exhibit tetragonal hausmannite structure. Formation of manganese oxide compound was confirmed from FTIR studies. The optical absorption showed existence of direct optical band gap of energy 2.30 eV. Mn{sub 3}O{sub 4} film surface showed hydrophilic nature with water contact angle of 55{sup o}. The supercapacitive properties of Mn{sub 3}O{sub 4} thin film investigated in 1 M Na{sub 2}SO{sub 4} electrolyte showed maximum supercapacitance of 314 F g{sup -1} at scan rate 5 mV s{sup -1}.

Structural transformation of sputtered o-LiMnO2 thin-film cathodes induced by electrochemical cycling

International Nuclear Information System (INIS)

Fischer, J.; Chang, K.; Ye, J.; Ulrich, S.; Ziebert, C.; Music, D.; Hallstedt, B.; Seifert, H.J.

2013-01-01

Orthorhombic LiMnO 2 (o-LiMnO 2 ) thin films were produced by non-reactive r.f. magnetron sputtering in combination with thermal post-annealing. Oxide phase formation was investigated by X-ray diffraction and Raman spectroscopy. In order to assign the X-ray signals and estimate the grain size, a simulation of the diffraction pattern was performed and compared with experimental data. The density of the films was determined to be 3.39 g/cm 3 using X-ray reflectivity. Electrochemical characterization was carried out by galvanostatic cycling and cyclic voltammetry of Li/o-LiMnO 2 half cells. There are distinct redox reactions at approx. 3 V and 4 V, whereas the latter splits into multiple peaks. Using ab initio calculations and thermodynamic models, Gibbs energies of o-LiMnO 2 and c-LiMn 2 O 4 were determined. The relation between these energies explains the irreversible phase transformation that has been observed during the cycling of the Li/o-LiMnO 2 half cell. - Highlights: • Quantitative, thermodynamic modeling of the o-LiMnO 2 /c-LiMn 2 O 4 phase transformation • First CV-investigations on magnetron sputtered nanocrystalline o-LiMnO 2 thin films • Synthesis of o-LiMnO 2 planar model systems for protective coating and SEI development

Epitaxial growth of Sb-doped nonpolar a-plane ZnO thin films on r-plane sapphire substrates by RF magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Chen, Hou-Guang, E-mail: houguang@isu.edu.tw [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan (China); Hung, Sung-Po [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 840, Taiwan (China)

2014-02-15

Highlights: ► Sb-doped nonpolar a-plane ZnO layers were epitaxially grown on sapphire substrates. ► Crystallinity and electrical properties were studied upon growth condition and doping concentration. ► The out-of-plane lattice spacing of ZnO films reduces monotonically with increasing Sb doping level. ► The p-type conductivity of ZnO:Sb film is closely correlated with annealing condition and Sb doping level. -- Abstract: In this study, the epitaxial growth of Sb-doped nonpolar a-plane (112{sup ¯}0) ZnO thin films on r-plane (11{sup ¯}02) sapphire substrates was performed by radio-frequency magnetron sputtering. The influence of the sputter deposition conditions and Sb doping concentration on the microstructural and electrical properties of Sb-doped ZnO epitaxial films was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and the Hall-effect measurement. The measurement of the XRD phi-scan indicated that the epitaxial relationship between the ZnO:Sb layer and sapphire substrate was (112{sup ¯}0){sub ZnO}//(11{sup ¯}02){sub Al{sub 2O{sub 3}}} and [11{sup ¯}00]{sub ZnO}//[112{sup ¯}0]{sub Al{sub 2O{sub 3}}}. The out-of-plane a-axis lattice parameter of ZnO films was reduced monotonically with the increasing Sb doping level. The cross-sectional transmission electron microscopy (XTEM) observation confirmed the absence of any significant antimony oxide phase segregation across the thickness of the Sb-doped ZnO epitaxial film. However, the epitaxial quality of the films deteriorated as the level of Sb dopant increased. The electrical properties of ZnO:Sb film are closely correlated with post-annealing conditions and Sb doping concentrations.

Drastic effect of the Mn-substitution in the strongly correlated semiconductor FeSb2.

Science.gov (United States)

Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki

2017-06-01

We report the effects of Mn substitution, corresponding to hole doping, on the electronic properties of the narrow gap semiconductor, FeSb2, using single crystals of Fe1- x Mn x Sb2 grown by the Sb flux method. The orthorhombic Pnnm structure was confirmed by powder X-ray diffraction (XRD) for the pure and Mn-substituted samples. Their crystal structure parameters were refined using the Rietveld method. The chemical composition was investigated by wavelength-dispersive X-ray spectroscopy (WDX). The solubility limit of Mn in FeSb2 is x max ˜ 0.05 and the lattice constants change monotonically with increasing the actual Mn concentration. A drastic change from semiconducting to metallic electronic transports was found at very low Mn concentration at x ˜ 0.01. Our experimental results and analysis indicate that the substitution of a small amount of Mn changes drastically the electronic state in FeSb2 as well as the Co-substitution does: closing of the narrow gap and emergence of the density of states (DOS) at the Fermi level.

Effect of Mn doping on the structural and optical properties of ZrO2 thin films prepared by sol–gel method

International Nuclear Information System (INIS)

Berlin, I. John; Lekshmy, S. Sujatha; Ganesan, V.; Thomas, P.V.; Joy, K.

2014-01-01

Homogeneous and transparent Mn doped ZrO 2 thin films were prepared by sol–gel dip coating method. The films were annealed in air atmosphere at 500 °C. The X-ray diffraction pattern of the undoped ZrO 2 thin film revealed a mixed phase of tetragonal and monoclinic ZrO 2 with preferred orientations along T(111) and M(− 111). Grazing Incidence X-ray Diffraction of Mn doped ZrO 2 thin films reveals the introduction of Mn interstitial in ZrO 2 which stabilize the mixed phase of ZrO 2 into tetragonal phase. Atomic force microscope image shows the addition of catalyst (Mn) which stops isotropic agglomeration of particles, instead of anisotropic agglomeration that occurred resulting in growth of particles in certain direction. Average transmittances of > 70% (in UV–vis region) were observed for all samples. The optical band gap decreased from 5.72 to 4.52 eV with increase in Mn doping concentration. The reduced band gap is due to the introduction of impurity levels in the band gap, by incorporation of the metal ions into the ZrO 2 lattice. The d-electron of Mn (t 2g level) can easily overlap with the ZrO 2 's valence band (VB) because t 2g of Mn is very close to VB of ZrO 2 . This overlap caused a wide VB and consequently decreases the band gap of ZrO 2 . The photoluminescence (PL) spectrum of undoped zirconia thin film exhibits an intense near band edge emission peak at 392.5 nm (3.15 eV) and weak emission peaks at 304 (4.07 eV), 604 nm (2.05 eV) and 766 nm (1.61 eV). Additional PL peaks were observed for Mn doped ZrO 2 located at around 420, 447 (blue), 483 (blue) and 529 (green) nm respectively. These peaks were due to the redox properties of various valence state of Mn in ZrO 2 . The prepared Mn doped ZrO 2 thin films can be applied in optical devices. - Highlights: • Mn-doped ZrO 2 thin films were prepared by sol–gel dip coating method. • Introduction of Mn interstitial in ZrO 2 stabilizes ZrO 2 into tetragonal phase. • The optical band gap

Defect Structure of High-Temperature-Grown GaMnSb/GaSb

International Nuclear Information System (INIS)

Romanowski, P.; Bak-Misiuk, J.; Dynowska, E.; Domagala, J.Z.; Wojciechowski, T.; Jakiela, R.; Sadowski, J.; Barcz, A.; Caliebe, W.

2010-01-01

GaMnSb/GaSb(100) layers with embedded MnSb inclusions have been grown at 720 K using MBE technique. This paper presents the investigation of the defect structure of Ga1-xMnxSb layers with different content of manganese (up to x = 0.07). X-ray diffraction method using conventional and synchrotron radiation was applied. Dimensions and shapes of inclusions were detected by scanning electron microscopy. Depth profiles of elements were measured using secondary ion mass spectroscopy technique. (authors)

Preparation and evaluation of Mn3GaN1-x thin films with controlled N compositions

Science.gov (United States)

Ishino, Sunao; So, Jongmin; Goto, Hirotaka; Hajiri, Tetsuya; Asano, Hidefumi

2018-05-01

Thin films of antiperovskite Mn3GaN1-x were grown on MgO (001) substrates by reactive magnetron sputtering, and their structural, magnetic, and magneto-optical properties were systematically investigated. It was found that the combination of the deposition rate and the N2 gas partial pressure could produce epitaxial films with a wide range of N composition (N-deficiency) and resulting c/a values (0.93 - 1.0). While the films with c/a = 0.992 - 1.0 were antiferromagnetic, the films with c/a = 0.93 - 0.989 showed perpendicular magnetic anisotropy (PMA) with the maximum PMA energy up to 1.5×106 erg/cm3. Systematic dependences of the energy spectra of the polar Kerr signals on the c/a ratio were observed, and the Kerr ellipticity was as large as 2.4 deg. at 1.9 eV for perpendicularly magnetized ferromagnetic thin films with c/a = 0.975. These results highlight that the tetragonal distortion plays an important role in magnetic and magneto-optical properties of Mn3GaN1-x thin films.

Hole-dominated transport in InSb nanowires grown on high-quality InSb films

Energy Technology Data Exchange (ETDEWEB)

Algarni, Zaina; George, David; Singh, Abhay; Lin, Yuankun; Philipose, U., E-mail: usha.philipose@unt.edu [University of North Texas, Department of Physics (United States)

2016-12-15

We have developed an effective strategy for synthesizing p-type indium antimonide (InSb) nanowires on a thin film of InSb grown on glass substrate. The InSb films were grown by a chemical reaction between Sb{sub 2}S{sub 3} and In and were characterized by structural, compositional, and optical studies. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies reveal that the surface of the substrate is covered with a polycrystalline InSb film comprised of sub-micron sized InSb islands. Energy dispersive X-ray (EDX) results show that the film is stoichiometric InSb. The optical constants of the InSb film, characterized using a variable-angle spectroscopic ellipsometer (VASE) shows a maximum value for refractive index at 3.7 near 1.8 eV, and the extinction coefficient (k) shows a maximum value 3.3 near 4.1 eV. InSb nanowires were subsequently grown on the InSb film with 20 nm sized Au nanoparticles functioning as the metal catalyst initiating nanowire growth. The InSb nanowires with diameters in the range of 40–60 nm exhibit good crystallinity and were found to be rich in Sb. High concentrations of anions in binary semiconductors are known to introduce acceptor levels within the band gap. This un-intentional doping of the InSb nanowire resulting in hole-dominated transport in the nanowires is demonstrated by the fabrication of a p-channel nanowire field effect transistor. The hole concentration and field effect mobility are estimated to be ≈1.3 × 10{sup 17} cm{sup −3} and 1000 cm{sup 2} V{sup −1} s{sup −1}, respectively, at room temperature, values that are particularly attractive for the technological implications of utilizing p-InSb nanowires in CMOS electronics.

Cation vacancies and electrical compensation in Sb-doped thin-film SnO2 and ZnO

International Nuclear Information System (INIS)

Korhonen, E; Prozheeva, V; Tuomisto, F; Bierwagen, O; Speck, J S; White, M E; Galazka, Z; Liu, H; Izyumskaya, N; Avrutin, V; Özgür, Ü; Morkoç, H

2015-01-01

We present positron annihilation results on Sb-doped SnO 2 and ZnO thin films. The vacancy types and the effect of vacancies on the electrical properties of these intrinsically n-type transparent semiconducting oxides are studied. We find that in both materials low and moderate Sb-doping leads to formation of vacancy clusters of variable sizes. However, at high doping levels cation vacancy defects dominate the positron annihilation signal. These defects, when at sufficient concentrations, can efficiently compensate the n-type doping produced by Sb. This is the case in ZnO, but in SnO 2 the concentrations appear too low to cause significant compensation. (invited article)

Cation vacancies and electrical compensation in Sb-doped thin-film SnO2 and ZnO

Science.gov (United States)

Korhonen, E.; Prozheeva, V.; Tuomisto, F.; Bierwagen, O.; Speck, J. S.; White, M. E.; Galazka, Z.; Liu, H.; Izyumskaya, N.; Avrutin, V.; Özgür, Ü.; Morkoç, H.

2015-02-01

We present positron annihilation results on Sb-doped SnO2 and ZnO thin films. The vacancy types and the effect of vacancies on the electrical properties of these intrinsically n-type transparent semiconducting oxides are studied. We find that in both materials low and moderate Sb-doping leads to formation of vacancy clusters of variable sizes. However, at high doping levels cation vacancy defects dominate the positron annihilation signal. These defects, when at sufficient concentrations, can efficiently compensate the n-type doping produced by Sb. This is the case in ZnO, but in SnO2 the concentrations appear too low to cause significant compensation.

Thin Co films with tunable ferromagnetic resonance frequency

International Nuclear Information System (INIS)

Maklakov, Sergey S.; Maklakov, Sergey A.; Ryzhikov, Ilya A.; Rozanov, Konstantin N.; Osipov, Alexey V.

2012-01-01

The tailored production of thin Co films of 50 nm thick with ferromagnetic resonance frequency in a range from 2.9 to 7.3 GHz using the DC magnetron sputtering is reported. The ferromagnetic resonance frequency, coercivity, effective magnetic field and nanocrystalline structure parameters are shown to be governed by the Co deposition rate. For this investigation, FMR, VSM and TEM techniques were used. - Highlights: ► Thin Co films with FMR frequency in a range from 2.9 to 7.3 GHz are obtained. ► The films' properties are governed by the deposition rate during DC magnetron sputtering. ► FMR, VSM and TEM techniques were used during the study.

Optical band gap study of a-Se and Se-Sb thin films

International Nuclear Information System (INIS)

Kaur, Ramandeep; Singh, Palwinder; Thakur, Anup

2016-01-01

Amorphous selenium (a-Se) and a-Se_9_5Sb_5 alloy were prepared using melt quenching technique. X-ray diffraction (XRD) pattern confirmed the amorphous nature of the prepared samples. Composition of the prepared samples has been determined using Energy dispersive X-ray fluorescence (EDXRF) technique. Differential thermal analysis (DTA) confirmed the glassy nature of the prepared samples. Thin films of the prepared samples were deposited on glass substrate using thermal evaporation method. Amorphous nature of the deposited films was confirmed using XRD. Optical properties of these films were obtained from the UV-VIS transmission spectra, at normal incidence, over 200-1100 nm spectral range. The optical absorption edge was described by using the model given by the Tauc. Optical band gap of the deposited films was calculated using Tauc plot. Optical characterization showed that average transmission and optical band gap decreased with the addition of antinomy.

The origin of magnetism in transition metal-doped ZrO2 thin films: Experiment and theory

KAUST Repository

Hong, Nguyenhoa

2013-10-04

We have investigated the magnetic properties of Fe/Co/Ni-doped ZrO 2 laser ablated thin films in comparison with the known results of Mn-doped ZrO2, which is thought to be a promising material for spintronics applications. It is found that doping with a transition metal can induce room temperature ferromagnetism in \\'fake\\' diamond. Theoretical analysis based on density functional theory confirms the experimental measurements, by revealing that the magnetic moments of Mn- and Ni-doped ZrO2 thin films are much larger than that of Fe- or Co-doped ZrO2 thin films. Most importantly, our calculations confirm that Mn- and Ni-doped ZrO2 show a ferromagnetic ground state in comparison to Co- and Fe-doped ZrO 2, which favor an antiferromagnetic ground state. © 2013 IOP Publishing Ltd.

Giant magnetoresistance and magnetostriction in Mn1.8Co0.2Sb

International Nuclear Information System (INIS)

Kushwaha, Pallavi; Lakhani, Archna; Rawat, R.

2007-01-01

We have studied the first order ferrimagnetic (FRI) to antiferromagnetic (AFM) transition in Mn l.8 Co 0.2 Sb by resistivity, magneto resistance and magnetostriction. With the application of magnetic field FRI to AFM transition temperature (T N ) decreases monotonically and hysteresis across the transition increases. Below T N FRI to AFM transition can be induced with the application of magnetic field which results in giant magnetoresistance and magnetostriction. The magnetostriction is found to be anomalous in this compound showing a small negative minimum close to critical field required for AFM to FRI transition. (author)

Red electroluminescent process excited by hot holes in SrGa2S4:Ce, Mn thin film

International Nuclear Information System (INIS)

Tanaka, Katsu; Okamoto, Shinji

2009-01-01

This paper reports the first observation of red electroluminescence (EL) in SrGa 2 S 4 :Ce, Mn thin film. The EL spectrum consists of single broad emission band having a peak wavelength of 665 nm. The dominant EL decay time was 31 μs. The relationship between the applied voltage and the EL waveform was measured in single insulating thin film electroluminescent (TFEL) devices. An asymmetric EL waveform was observed in SrGa 2 S 4 :Ce, Mn TFEL devices under a rectangular applied voltage. The polarity of the EL waveform in these devices was different from the waveform in manganese-activated zinc sulfide ZnS:Mn devices. This indicates that hot holes excite the Mn 2+ ions to cause the red EL.

Hole-dominated transport in InSb nanowires grown on high-quality InSb films

Science.gov (United States)

Algarni, Zaina; George, David; Singh, Abhay; Lin, Yuankun; Philipose, U.

2016-12-01

We have developed an effective strategy for synthesizing p-type indium antimonide (InSb) nanowires on a thin film of InSb grown on glass substrate. The InSb films were grown by a chemical reaction between S b 2 S 3 and I n and were characterized by structural, compositional, and optical studies. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies reveal that the surface of the substrate is covered with a polycrystalline InSb film comprised of sub-micron sized InSb islands. Energy dispersive X-ray (EDX) results show that the film is stoichiometric InSb. The optical constants of the InSb film, characterized using a variable-angle spectroscopic ellipsometer (VASE) shows a maximum value for refractive index at 3.7 near 1.8 eV, and the extinction coefficient (k) shows a maximum value 3.3 near 4.1 eV. InSb nanowires were subsequently grown on the InSb film with 20 nm sized Au nanoparticles functioning as the metal catalyst initiating nanowire growth. The InSb nanowires with diameters in the range of 40-60 nm exhibit good crystallinity and were found to be rich in Sb. High concentrations of anions in binary semiconductors are known to introduce acceptor levels within the band gap. This un-intentional doping of the InSb nanowire resulting in hole-dominated transport in the nanowires is demonstrated by the fabrication of a p-channel nanowire field effect transistor. The hole concentration and field effect mobility are estimated to be ≈1.3 × 1017 cm-3 and 1000 cm2 V-1 s-1, respectively, at room temperature, values that are particularly attractive for the technological implications of utilizing p-InSb nanowires in CMOS electronics.

Growth of different phases and morphological features of MnS thin films by chemical bath deposition: Effect of deposition parameters and annealing

Energy Technology Data Exchange (ETDEWEB)

Hannachi, Amira, E-mail: amira.hannachi88@gmail.com; Maghraoui-Meherzi, Hager

2017-03-15

Manganese sulfide thin films have been deposited on glass slides by chemical bath deposition (CBD) method. The effects of preparative parameters such as deposition time, bath temperature, concentration of precursors, multi-layer deposition, different source of manganese, different complexing agent and thermal annealing on structural and morphological film properties have been investigated. The prepared thin films have been characterized using the X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). It exhibit the metastable forms of MnS, the hexagonal γ-MnS wurtzite phase with preferential orientation in the (002) plane or the cubic β-MnS zinc blende with preferential orientation in the (200) plane. Microstructural studies revealed the formation of MnS crystals with different morphologies, such as hexagons, spheres, cubes or flowers like. - Graphical Abstract: We report the preparation of different phases of manganese sulfide thin films (γ, β and α-MnS) by chemical bath deposition method. The effects of deposition parameters such as deposition time and temperature, concentrations of precursors and multi-layer deposition on MnS thin films structure and morphology were investigated. The influence of thermal annealing under nitrogen atmosphere at different temperature on MnS properties was also studied. Different manganese precursors as well as different complexing agent were also used. - Highlights: • γ and β-MnS films were deposited on substrate using the chemical bath deposition. • The effect of deposition parameters on MnS film properties has been investigated. • Multi-layer deposition was also studied to increase film thickness. • The effect of annealing under N{sub 2} at different temperature was investigated.

Enhanced Charge Extraction of Li-Doped TiO2 for Efficient Thermal-Evaporated Sb2S3 Thin Film Solar Cells

Science.gov (United States)

Lan, Chunfeng; Luo, Jingting; Lan, Huabin; Fan, Bo; Peng, Huanxin; Zhao, Jun; Sun, Huibin; Zheng, Zhuanghao; Liang, Guangxing; Fan, Ping

2018-01-01

We provided a new method to improve the efficiency of Sb2S3 thin film solar cells. The TiO2 electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb2S3 solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO2 films. Compared with the undoped TiO2, Li-doped mesoporous TiO2 dramatically improved the photo-voltaic performance of the thermal-evaporated Sb2S3 thin film solar cells, with the average power conversion efficiency (PCE) increasing from 1.79% to 4.03%, as well as the improved open-voltage (Voc), short-circuit current (Jsc) and fill factors. The best device based on Li-doped TiO2 achieved a power conversion efficiency up to 4.42% as well as a Voc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb2S3 solar cells. This study showed that Li-doping on TiO2 can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb2S3-based solar cells. PMID:29495612

Enhanced Charge Extraction of Li-Doped TiO2 for Efficient Thermal-Evaporated Sb2S3 Thin Film Solar Cells

Directory of Open Access Journals (Sweden)

Chunfeng Lan

2018-02-01

Full Text Available We provided a new method to improve the efficiency of Sb2S3 thin film solar cells. The TiO2 electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb2S3 solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO2 films. Compared with the undoped TiO2, Li-doped mesoporous TiO2 dramatically improved the photo-voltaic performance of the thermal-evaporated Sb2S3 thin film solar cells, with the average power conversion efficiency (PCE increasing from 1.79% to 4.03%, as well as the improved open-voltage (Voc, short-circuit current (Jsc and fill factors. The best device based on Li-doped TiO2 achieved a power conversion efficiency up to 4.42% as well as a Voc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb2S3 solar cells. This study showed that Li-doping on TiO2 can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb2S3-based solar cells.

Metallic transport and large anomalous Hall effect at room temperature in ferrimagnetic Mn{sub 4}N epitaxial thin film

Energy Technology Data Exchange (ETDEWEB)

Shen, Xi; Shigematsu, Kei [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Chikamatsu, Akira, E-mail: chikamatsu@chem.s.u-tokyo.ac.jp; Fukumura, Tomoteru [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033 (Japan); Hirose, Yasushi; Hasegawa, Tetsuya [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)

2014-08-18

We report the electrical transport properties of ferrimagnetic Mn{sub 4}N (001) epitaxial thin films grown by pulsed laser deposition on MgO (001) substrates. The Mn{sub 4}N thin films were tetragonally distorted with a ratio of out-of-plane to in-plane lattice constants of 0.987 and showed perpendicular magnetic anisotropy with an effective magnetic anisotropy constant of 0.16 MJ/m{sup 3}, which is comparable with that of a recently reported molecular-beam-epitaxy-grown film. The thin films exhibited metallic transport with a room temperature resistivity of 125 μΩ cm in addition to a large anomalous Hall effect with a Hall angle tangent of 0.023.

Electroless plating of low-resistivity Cu–Mn alloy thin films with self-forming capacity and enhanced thermal stability

Energy Technology Data Exchange (ETDEWEB)

Chen, Sung-Te, E-mail: stchen@mail.hust.edu.tw [Department of Electronic Engineering, Hsiuping University of Science and Technology, Dali 412, Taichung, Taiwan (China); Chen, Giin-Shan [Department of Materials Science and Engineering, Feng Chia University, Seatwen 407, Taichung, Taiwan (China)

2015-11-05

Previous studies have typically used sputter deposition to fabricate Cu–Mn alloy thin films with concentrated solute additions which have exceeded several atomic percentages, and the electrical resistivity values of the resultant films from previous studies are relatively high, ranging from 2.5 to 3.5 μΩ-cm. Herein, we proposed a different approach by using electroless process to plate dilute Cu–Mn (0.1 at.%) alloy thin films on dielectric layers (SiO{sub 2}). Upon forming-gas annealing, the Mn incorporated into Cu–Mn films was segregated toward the SiO{sub 2} side, eventually converting itself into a few atomic layer thickness at the Cu/SiO{sub 2} interface, and forming films with a low level of resistivity the same as that of pure Cu films (2.0 μΩ-cm). The interfacial layer served as not only a diffusion barrier, but also an adhesion promoter that prevented the film’s agglomeration during annealing at elevated temperatures. The mechanism for the dual-function performance by the Mn addition was elucidated by interfacial bonding analysis, as well as dynamic (adhesive strength) and thermodynamic (surface-tension) measurements. - Highlights: • Electroless plating is proposed to grow dilute (0.1%) Cu–Mn films on SiO{sub 2} layers. • Adequate annealing results in a self-forming of MnO{sub x} at the Cu/SiO{sub 2} interface. • The role of interfacial MnO{sub x} as a barrier and adhesion promoter is demonstrated. • The treated dilute film has a low ρ level of pure Cu, in contrast to concentrated films. • Its potential as a single entity replacement of Cu interconnect is presented.

Noncollinear antiferromagnetic Mn3Sn films

Science.gov (United States)

Markou, A.; Taylor, J. M.; Kalache, A.; Werner, P.; Parkin, S. S. P.; Felser, C.

2018-05-01

Noncollinear hexagonal antiferromagnets with almost zero net magnetization were recently shown to demonstrate giant anomalous Hall effect. Here, we present the structural and magnetic properties of noncollinear antiferromagnetic Mn3Sn thin films heteroepitaxially grown on Y:ZrO2 (111) substrates with a Ru underlayer. The Mn3Sn films were crystallized in the hexagonal D 019 structure with c -axis preferred (0001) crystal orientation. The Mn3Sn films are discontinuous, forming large islands of approximately 400 nm in width, but are chemical homogeneous and characterized by near perfect heteroepitaxy. Furthermore, the thin films show weak ferromagnetism with an in-plane uncompensated magnetization of M =34 kA/m and coercivity of μ0Hc=4.0 mT at room temperature. Additionally, the exchange bias effect was studied in Mn3Sn /Py bilayers. Exchange bias fields up to μ0HEB=12.6 mT can be achieved at 5 K. These results show Mn3Sn films to be an attractive material for applications in antiferromagnetic spintronics.

Perpendicular magnetic anisotropy in Mn2VIn (001) films: An ab initio study

Science.gov (United States)

Zipporah, Muthui; Robinson, Musembi; Julius, Mwabora; Arti, Kashyap

2018-05-01

First principles study of the magnetic anisotropy of Mn2VIn (001) films show perpendicular magnetic anisotropy (PMA), which increases as a function of the thickness of the film. Density functional theory (DFT) as implemented in the Vienna Ab initio simulation package (VASP) is employed here to perform a comprehensive theoretical investigation of the structural, electronic and magnetic properties of the Mn2VIn(001) films of varying thickness. Our calculations were performed on fully relaxed structures, with five to seventeen mono layers (ML). The degree of spin polarization is higher in the (001) Mn2VIn thin films as compared to the bulk in contrast to what is usually the case and as in Mn2VAl, which is isoelectronic to Mn2VIn as well as inCo2VIn (001) films studied for comparison. Tetragonal distortions are found in all the systems after relaxation. The distortion in the Mn2VIn system persists even for the 17ML thin film, resulting in PMA in the Mn2VIn system. This significant finding has potential to contribute to spin transfer torque (STT) and magnetic random access memory MRAM applications, as materials with PMA derived from volume magnetocrystalline anisotropy are being proposed as ideal magnetic electrodes.

Growth of metastable fcc Mn thin film on GaAs(001) and its electronic structure studied by photoemission with synchrotron radiation

International Nuclear Information System (INIS)

Chen Yan; Dong Guosheng; Zhang Ming

1995-01-01

The epitaxial growth of metastable fcc Mn thin films on GaAs(001) surface has been achieved at a substrate temperature of 400 K. The development of the fcc Mn thin films as a function of coverage is studied by photoemission with synchrotron radiation. The electron density of states below the Fermi edge of the fcc Mn phase is measured. A significant difference of the electronic structures is observed between the metastable fcc Mn phase and the thermodynamically stable α-Mn phase. Possible mechanisms are proposed to interpret the experimental result

Effect of tungsten on the phase-change properties of Ge{sub 8}Sb{sub 2}Te{sub 11} Thin Films for the Phase-change device

Energy Technology Data Exchange (ETDEWEB)

Park, Cheol-Jin; Kong, Heon; Lee, Hyun-Yong; Yeo, Jong-Bin [Chonnam National University, Gwangju (Korea, Republic of)

2017-07-15

In this study, the electrical, optical, and structural properties of tungsten (W)-doped Ge{sub 8}Sb{sub 2}Te{sub 11} thin films were investigated. Previously, GeSbTe alloys were doped with various materials in an attempt to improve the thermal stability. Ge{sub 8}Sb{sub 2}Te{sub 11} and W-doped Ge{sub 8}Sb{sub 2}Te{sub 11} films with a thickness of 200 nm were fabricated by using an RF magnetron reactive co-sputtering system at room temperature on Si (p-type, 100) and glass substrate. The fabricated thin films were annealed in a furnace in the ∼ 0 - 400 ℃ temperature range. The optical properties were analyzed using a UV-Vis-IR spectrophotometer, and by using Beer’s Law equation, the optical-energy band gap (E{sub op}), slope B{sup 1/2}, and slope 1/F were calculated. For the crystalline materials, an increase in the slope B{sup 1/2} and 1/F was observed, exhibiting a good effect on the thermal stability in the amorphous state after the phase change. The structural properties were analyzed by X-ray diffraction, and the result showed that the W-doped Ge{sub 8}Sb{sub 2}Te{sub 11} had a face-centered-cubic (fcc) crystalline structure increased crystallization temperature (T{sub c}). An increase in the T{sub c} increased the thermal stability in the amorphous state. The electrical properties were analyzed using a 4-point probe, exhibiting an increase in the sheet resistance (R{sub s}) in the amorphous and the crystalline states indicating a reduced programming current in the memory device.

Effects of doping on ferroelectric properties and leakage current behavior of KNN-LT-LS thin films on SrTiO3 substrate

Science.gov (United States)

Abazari, M.; Safari, A.

2009-05-01

We report the effects of Ba, Ti, and Mn dopants on ferroelectric polarization and leakage current of (K0.44Na0.52Li0.04)(Nb0.84Ta0.1Sb0.06)O3 (KNN-LT-LS) thin films deposited by pulsed laser deposition. It is shown that donor dopants such as Ba2+, which increased the resistivity in bulk KNN-LT-LS, had an opposite effect in the thin film. Ti4+ as an acceptor B-site dopant reduces the leakage current by an order of magnitude, while the polarization values showed a slight degradation. Mn4+, however, was found to effectively suppress the leakage current by over two orders of magnitude while enhancing the polarization, with 15 and 23 μC/cm2 remanent and saturated polarization, whose values are ˜70% and 82% of the reported values for bulk composition. This phenomenon has been associated with the dual effect of Mn4+ in KNN-LT-LS thin film, by substituting both A- and B-site cations. A detailed description on how each dopant affects the concentrations of vacancies in the lattice is presented. Mn-doped KNN-LT-LS thin films are shown to be a promising candidate for lead-free thin films and applications.

Thin films of copper antimony sulfide: A photovoltaic absorber material

Energy Technology Data Exchange (ETDEWEB)

Ornelas-Acosta, R.E. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450 (Mexico); Shaji, S. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450 (Mexico); Universidad Autónoma de Nuevo León-CIIDIT, Apodaca, Nuevo León (Mexico); Avellaneda, D.; Castillo, G.A.; Das Roy, T.K. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450 (Mexico); Krishnan, B., E-mail: kbindu_k@yahoo.com [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450 (Mexico); Universidad Autónoma de Nuevo León-CIIDIT, Apodaca, Nuevo León (Mexico)

2015-01-15

Highlights: • CuSbS{sub 2} thin films were prepared by heating Sb{sub 2}S{sub 3}/Cu layers. • Analyzed the structure, composition, optical, and electrical properties. • PV structures: glass/SnO{sub 2}:F/n-CdS/p-CuSbS{sub 2}/C/Ag were formed at different conditions. • The PV parameters (J{sub sc}, V{sub oc}, and FF) were evaluated from the J–V characteristics. • J{sub sc}: 0.52–3.20 mA/cm{sup 2}, V{sub oc}:187–323 mV, FF: 0.27–0.48 were obtained. - Abstract: In this work, we report preparation and characterization of CuSbS{sub 2} thin films by heating glass/Sb{sub 2}S{sub 3}/Cu layers and their use as absorber material in photovoltaic structures: glass/SnO{sub 2}:F/n-CdS/p-CuSbS{sub 2}/C/Ag. The Sb{sub 2}S{sub 3} thin films of 600 nm were prepared by chemical bath deposition on which copper thin films of 50 nm were thermally evaporated, and the glass/Sb{sub 2}S{sub 3}/Cu multilayers were heated in vacuum at different temperatures. X-ray diffraction analysis showed the formation of orthorhombic CuSbS{sub 2} after heating the precursor layers. Studies on identification and chemical state of the elements were done using X-ray photoelectron spectroscopy. The optical band gap of the CuSbS{sub 2} thin films was 1.55 eV and the thin films were photoconductive. The photovoltaic parameters of the devices using CuSbS{sub 2} as absorber and CdS as window layer were evaluated from the J–V curves, yielding J{sub sc}, V{sub oc}, and FF values in the range of 0.52–3.20 mA/cm{sup 2}, 187–323 mV, and 0.27–0.48, respectively, under illumination of AM1.5 radiation.

Structural properties of calcogenic thin films and alloys subjected to synchrotron light

International Nuclear Information System (INIS)

Moura, P.R.; Almeida, D.P.; Lima, J.C. de; Campos, C.E.M.; Ponciano, C.R.

2009-01-01

Results on structural characterization of Sb 50 Te 50 and Te 24 In 38 Sb 38 alloys prepared as powder and after deposited as a thin films are presented. For that x ray diffraction and energy dispersive X-ray fluorescence were used. The nanocrystalline phases Sb 2 Te 2 and Sb 24 Te 9 were nucleated in both Sb 50 Te 50 and Te 24 In 38 Sb 38 alloys, respectively. The thin films of both binary and ternary alloys are mainly amorphous. According to X-ray fluorescence results the chemical composition inside the ultraviolet irradiated region on one of the binary thin film become different than that outside irradiation marks, suggesting Sb migration. (author)

Magnetic and exchange bias properties of YCo thin films and IrMn/YCo bilayers

Science.gov (United States)

Venkat Narayana, M.; Manivel Raja, M.; Jammalamadaka, S. Narayana

2018-02-01

We report on the structural and magnetic properties of YCo thin films and IrMn/YCo bilayers. X-ray diffraction infer that all the films are amorphous in nature. Magnetization versus magnetic field measurements reveal room temperature soft ferromagnetism in all the YCo films. Thin films which were grown at 100 W sputter power with growth rates of 0.677, 0.694 and 0.711 Å/sec show better morphology and composition than 50 W (0.333, 0.444 and 0.277 Å/sec) grown films. Perpendicular exchange bias in as deposited bilayers is evident for IrMn/YCo bilayers. Exchange bias (EB) decreases in case of in plane measurements and enhances for out of plane measurements after perpendicular field annealing. EB is more in case of out of plane direction due to large perpendicular anisotropy in comparison with in plane direction. Above the critical thickness, EB variation is explained on the basis of random field model in the Heisenberg regime, which has been proposed by Malozemoff. Indeed there exists an inverse relationship between EB and IrMn layer thickness. Evidenced vertical shift apart from the horizontal shift for magnetization loops is attributed to frozen magnetic moments in one of the layers at the interface. Present results would prove to be helpful in spintronic device applications.

Facile chemical synthesis of nanoporous layered δ-MnO{sub 2} thin film for high-performance flexible electrochemical capacitors

Energy Technology Data Exchange (ETDEWEB)

Hu, Yu; Wang, Jun; Jiang, Xionghua; Zheng, Yanfeng [The Key Laboratory of Low-Carbon Chemistry and Energy Conservation of Guangdong Province, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Chen, Zhenxing, E-mail: chenzx65@mail.sysu.edu.cn [The Key Laboratory of Low-Carbon Chemistry and Energy Conservation of Guangdong Province, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

2013-04-15

Layered δ-MnO{sub 2} thin films with a three-dimensional nanostructure are successfully fabricated on stainless steel foil substrates for flexible electrochemical capacitors by a facile and effective chemical bath deposition technology from ethanol and potassium permanganate solution at 15 °C. The as-prepared thin films display nanoporous morphology and a water contact angle of 20°. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses reveal that the thin films are composed of δ-MnO{sub 2}. Electrochemical data demonstrate that the δ-MnO{sub 2} thin film electrodes can deliver a high special capacitance of 447 F/g at 2 mV/s, and provide a good capacitance retention ratio of 87% after 1000 continuous cycles at 10 mV/s in 0.5 M Na{sub 2}SO{sub 4}. Compressive and tensile bending tests show that the as-prepared electrodes can steadily work over a wide range of applied curvatures between −2.5 cm{sup −1} (tension) and 2.5 cm{sup −1} (compression). Only a small decrease in special capacitance (0.9% at a curvature of 2.5 cm{sup −1} under compressive strain, or 1.2% at a curvature of −2.5 cm{sup −1} under tensile strain) is observed even after bending for 200 cycles, indicating the excellent mechanical flexibility and electrochemical stability of the δ-MnO{sub 2} thin film electrodes.

Refractive index modulation of Sb70Te30 phase-change thin films by multiple femtosecond laser pulses

International Nuclear Information System (INIS)

Lei, Kai; Wang, Yang; Jiang, Minghui; Wu, Yiqun

2016-01-01

In this study, the controllable effective refractive index modulation of Sb 70 Te 30 phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.

Changes of optical, dielectric, and structural properties of Si15Sb85 phase change memory thin films under different initializing laser power

International Nuclear Information System (INIS)

Huang Huan; Zhang Lei; Wang Yang; Han Xiaodong; Wu Yiqun; Zhang Ze; Gan Fuxi

2011-01-01

Research highlights: → We study the optical, dielectric, and structural characteristics of Si 15 Sb 85 phase change memory thin films under a moving continuous-wave laser initialization. → The optical and dielectric constants, absorption coefficient of Si 15 Sb 85 change regularly with the increasing laser power. → The optical band gaps of Si 15 Sb 85 irradiated upon different power lasers were calculated. → HRTEM images of the samples were observed and the changes of optical and dielectric constants are determined by crystalline structures changes of the films. - Abstract: The optical, dielectric, and structural characteristics of Si 15 Sb 85 phase change memory thin films under a moving continuous-wave laser initialization are studied by using spectroscopic ellipsometry and high-resolution transmission electron microscopy. The dependence of complex refractive index, dielectric functions, absorption coefficient, and optical band gap of the films on its crystallization extents formed by the different initialization laser power are analyzed in detail. The structural change from as-deposited amorphous phase to distorted rhombohedra-Sb-like crystalline structure with the increase of initialization laser power is clearly observed with sub-nanometer resolution. The optical and dielectric constants, the relationship between them, and the local atomic arrangements of this new phase change material can help explain the phase change mechanism and design the practical phase change memory devices.

Magnetic domain structure of MnAs thin films as a function of temperature

International Nuclear Information System (INIS)

Mizuguchi, Masaki; Manago, Takashi; Akinaga, Hiroyuki; Kuramochi, Hiromi; Okabayashi, Jun

2003-01-01

We have investigate magnetic domain structures of MnAs thin films grown on GaAs substrates by a magnetic force microscope. We observed, by an atomic force microscope, rectangular defects along GaAs [110] direction which disperse randomly on the surface of MnAs/GaAs(001). The Curie temperature of MnAs is 45degC, and it is successfully confirmed directly by the variable temperature magnetic force microscope observation. We also investigated magnetic domain structures of MnAs/GaAs(111)B, and no apparent relation was observed between the topographic structure and the magnetic domain structure. (author)

Composition, structure and magnetic properties of sputter deposited Ni-Mn-Ga ferromagnetic shape memory thin films

Energy Technology Data Exchange (ETDEWEB)

Annadurai, A.; Nandakumar, A.K.; Jayakumar, S.; Kannan, M.D. [Thin Film Center, Department of Physics, PSG College of Technology, Coimbatore 641004 (India); Manivel Raja, M.; Bysak, S. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad, Andhra Pradesh 500 058 (India); Gopalan, R. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad, Andhra Pradesh 500 058 (India)], E-mail: rg_gopy@yahoo.com; Chandrasekaran, V. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad, Andhra Pradesh 500 058 (India)

2009-03-15

Polycrystalline Ni-Mn-Ga thin films were deposited by the d.c. magnetron sputtering on well-cleaned substrates of Si(1 0 0) and glass at a constant sputtering power of 36 W. We report the influence of sputtering pressure on the composition, structure and magnetic properties of the sputtered thin films. These films display ferromagnetic behaviour only after annealing at an elevated temperature and a maximum saturation magnetization of 335 emu/cc was obtained for the films investigated. Evolution of martensitic microstructure was observed in the annealed thin films with the increase of sputtering pressure. The thermo-magnetic curves exhibited only magnetic transition in the temperature range of 339-374 K. The thin film deposited at high sputtering pressure of 0.025 mbar was found to be ordered L2{sub 1} austenitic phase.

Semiclassical electronic transport in MnAs thin films

International Nuclear Information System (INIS)

Helman, C.; Milano, J.; Steren, L.; Llois, A.M.

2008-01-01

Magneto-transport experiments have been recently performed on MnAs thin films. Hall effect and transverse magnetoresistance measurements have shown interesting and, until now, unknown results. For instance, the transverse magnetoresistance shows no saturation in the presence of very high magnetic fields. In order to understand the contribution of the electronic band structure to the non-saturating magnetoresistance, we perform ab initio calculations, using the Wien2K code and analyze the magneto-transport properties within the semiclassical approximation. We show that non-saturation may be due to the presence of open orbits on the majority Fermi surface

Semiclassical electronic transport in MnAs thin films

Energy Technology Data Exchange (ETDEWEB)

Helman, C. [Dpto de Fisica, ' Juan Jose Giambiagi' , Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Unidad de Actividad Fisica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Buenos Aires (Argentina)], E-mail: helman@tandar.cnea.gov.ar; Milano, J.; Steren, L. [Departamento de Fisica, Centro Atomico Bariloche, Comision Nacional de Energia Atomica, S.C. Bariloche (Argentina); Llois, A.M. [Dpto de Fisica, ' Juan Jose Giambiagi' , Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires (Argentina); Unidad de Actividad Fisica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Buenos Aires (Argentina)

2008-07-15

Magneto-transport experiments have been recently performed on MnAs thin films. Hall effect and transverse magnetoresistance measurements have shown interesting and, until now, unknown results. For instance, the transverse magnetoresistance shows no saturation in the presence of very high magnetic fields. In order to understand the contribution of the electronic band structure to the non-saturating magnetoresistance, we perform ab initio calculations, using the Wien2K code and analyze the magneto-transport properties within the semiclassical approximation. We show that non-saturation may be due to the presence of open orbits on the majority Fermi surface.

Oxygen incorporation effects in annealed epitaxial La(1-x)SrxMnO3 thin films

International Nuclear Information System (INIS)

Petrisor, T.; Gabor, M. S.; Tiusan, C.; Boulle, A.; Bellouard, C.; Pana, O.; Petrisor, T.

2011-01-01

This paper presents our results regarding oxygen incorporation effects in epitaxial La (1-x) Sr x MnO 3 thin films, deposited on SrTiO 3 (001) single crystal substrates, by annealing in different gas mixtures of argon and oxygen. A particular emphasis is placed on the correlation of structural properties with the magnetic properties of the films, Curie temperature, and coercive field. In this sense, we demonstrate that the evolution of the diffuse part of the ω-scans performed on the films are due to oxygen excess in the film lattice, which creates cationic vacancies within the films. Also, we show that two regimes of oxygen incorporation in the films exist, one in which the films evolve toward a single phase and oxygen stoichiometry is recovered, and a second one dominated by oxygen over-doping effects. In order to support our study, XPS measurements were performed, from which we have evaluated the Mn 3+ /Mn 4+ ionic ratio.

Magnetic phase change in Mn-doped ZnSnAs2 thin films depending on Mn concentration

Science.gov (United States)

Uchitomi, Naotaka; Hidaka, Shiro; Saito, Shin; Asubar, Joel T.; Toyota, Hideyuki

2018-04-01

The relationship between Mn concentration and Curie temperature (TC) is studied for Mn-doped ZnSnAs2 ferromagnetic semiconductors, epitaxially grown on InP substrates by molecular beam epitaxy. In the ferromagnetic phase, Mn distributions in a (Zn,Mn,Sn)As2 thin film with 7.2 cation percent (cat. %) Mn are investigated using three-dimensional atom probe tomography. The results indicate an inhomogeneous distribution which spreads to a relatively high Mn concentration of 9.0 at. % (at. %). In the paramagnetic phase, it is found that the paramagnetic to ferromagnetic transition takes place sharply with a TC of 334 K when the Mn doping concentration increases to about 4 cat. % Mn, which corresponds to a magnetic percolation threshold for ferromagnetism in (Zn,Mn,Sn)As2. An effective Curie temperature ⟨TC⟩ is considered to bridge the Curie temperatures obtained experimentally to those calculated theoretically in inhomogeneous magnetic semiconductors. The behavior of magnetism in Mn-doped ZnSnAs2 can be explained by three different phases within the present framework.

Multi-level storage and ultra-high speed of superlattice-like Ge50Te50/Ge8Sb92 thin film for phase-change memory application.

Science.gov (United States)

Wu, Weihua; Chen, Shiyu; Zhai, Jiwei; Liu, Xinyi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-10-06

Superlattice-like Ge 50 Te 50 /Ge 8 Sb 92 (SLL GT/GS) thin film was systematically investigated for multi-level storage and ultra-fast switching phase-change memory application. In situ resistance measurement indicates that SLL GT/GS thin film exhibits two distinct resistance steps with elevated temperature. The thermal stability of the amorphous state and intermediate state were evaluated with the Kissinger and Arrhenius plots. The phase-structure evolution revealed that the amorphous SLL GT/GS thin film crystallized into rhombohedral Sb phase first, then the rhombohedral GeTe phase. The microstructure, layered structure, and interface stability of SLL GT/GS thin film was confirmed by using transmission electron microscopy. The transition speed of crystallization and amorphization was measured by the picosecond laser pump-probe system. The volume variation during the crystallization was obtained from x-ray reflectivity. Phase-change memory (PCM) cells based on SLL GT/GS thin film were fabricated to verify the multi-level switching under an electrical pulse as short as 30 ns. These results illustrate that the SLL GT/GS thin film has great potentiality in high-density and high-speed PCM applications.

Analysis of multiferroic properties in BiMnO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Grizalez, M [Universidad de la Amazonia, Florencia (Colombia); Mendoza, G A [Department of Physics, Universidad Nacional de Colombia, Bogota (Colombia); Prieto, P, E-mail: pprieto@calima.univalle.edu.c [Center of Excellence on Novel Materials - CENM (Colombia)

2009-05-01

Textured BiMnO{sub 3} [111] thin films on SrTiO{sub 3} (100) and Pt/TiO{sub 2}/SiO{sub 2} substrates were grown via r.f. magnetron sputtering (13.56 MHz). The XRD spectra confirmed a monoclinic structure and high-quality textured films for the BiMnO{sub 3} films. The films grown on SrTiO{sub 3} (100) showed higher crystalline quality than those developed on Pt/TiO{sub 2}/SiO{sub 2}. Through optimized oxygen pressure of 5x10{sup -2} mbar during the r.f. sputtering deposition, the crystalline orientation of the BiMnO{sub 3} film was improved with respect to the previously reported value of 2x10{sup -1} mbar. The values of spontaneous polarization (P{sub s}), remnant polarization (P{sub r}), and coercive field (F{sub c}) from ferroelectric hysteresis loops (P-E) at different temperatures were also obtained. Samples with higher crystalline order revealed better dielectric properties (high P{sub s} and P{sub r} values and a low F{sub c}). For films on both types of substrates, the ferroelectric behavior was found to persist up to 400K. Measurements at higher temperatures were difficult to obtain given the increased conductivity of the films. Magnetic hysteresis loops from 5K to 120K were obtained for BiMnO{sub 3} films grown on SrTiO{sub 3} and Pt/TiO{sub 2}/SiO{sub 2} substrates. The results suggested that the coexistence of the magnetic and electric phases persists up to 120K.

On Some Physical Properties of GeSe3-Sb2Se3-ZnSe Thin Films and Their Radiation Response

International Nuclear Information System (INIS)

Hosni, H.M.M.A.

2010-01-01

Thin films of the chalcogenides GeSe 3 , Sb 2 Se 3 , ZnSe, (GeSe 3 )80(Sb 2 Se 3 )20 and (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20, are prepared by thermal evaporation onto glass substrates. The effect of ZnSe incorporation with both GeSe 3 , Sb 2 Se 3 results in amorphous (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 composition as obtained from the X-ray analysis. Electrical measurements reveal a decrease in dc activation energy, ΔEdc, and an increase in ac activation energy, ΔEac, for (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 as compared with (GeSe 3 )80(Sb 2 Se 3 )20. Optical energy gap, Eg, and band tail width, Ee, are estimated in UV/VIS spectral region for fresh and γ-irradiated films, revealing a decrease in Eg and an increase in Ee for ZnSe and (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 compositions, with irradiation dose.

Electrical Transport and Magnetoresistance Properties of Tensile-Strained CaMnO3 Thin Films

Science.gov (United States)

Ullery, Dustin; Lawson, Bridget; Zimmerman, William; Neubauer, Samuel; Chaudhry, Adeel; Hart, Cacie; Yong, Grace; Smolyaninova, Vera; Kolagani, Rajeswari

We will present our studies of the electrical transport and magnetoresistance properties of tensile strained CaMnO3 thin films. We observe that the resistivity decreases significantly as the film thickness decreases which is opposite to what is observed in thin films of hole doped manganites. The decrease in resistivity is more pronounced in the films on (100) SrTiO3, with resistivity of the thinnest films being about 3 orders of magnitude lower than that of bulk CaMnO3. Structural changes accompanying resistivity changes cannot be fully explained as due to tensile strain, and indicate the presence of oxygen vacancies. These results also suggest a coupling between tensile strain and oxygen deficiency, consistent with predictions from models based on density functional theory calculations. We observe a change in resistance under the application of moderate magnetic field. Experiments are underway to understand the origin of the magnetoresistance and its possible relation to the tensile strain effects. We acknowledge support from: Towson Office of University Undergraduate Research, Fisher Endowment Grant and Undergraduate Research Grants from the Fisher College of Science and Mathematics, and Seed Funding Grant from the School of Emerging technologies.

A green and facile hydrothermal approach for the synthesis of high-quality semi-conducting Sb{sub 2}S{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Liu, Meng; Gong, Yongshuai; Li, Zhilin; Dou, Meiling, E-mail: douml@mail.buct.edu.cn; Wang, Feng, E-mail: wangf@mail.buct.edu.cn

2016-11-30

Highlights: • A green and facile hydrothermal approach for Sb{sub 2}S{sub 3} films was developed. • The film possessed a relatively ideal S/Sb atomic ratio and a compact surface. • The grain size of Sb{sub 2}S{sub 3} was increased by high temperature annealing. • The film annealed at 450 °C showed the improved optical and electrical performance. - Abstract: High-quality semi-conducting antimony sulfide (Sb{sub 2}S{sub 3}) thin films were directly deposited on the indium tin oxide (ITO) substrates by a green and facile one-step approach based on a hydrothermal reaction and post-annealing process without any assistance of complexing agents. The obtained Sb{sub 2}S{sub 3} films possessed a relatively ideal S/Sb atomic ratio and a compact and continuous surface as the grain size of Sb{sub 2}S{sub 3} was increased by high temperature annealing. The Sb{sub 2}S{sub 3} film annealed at 450 °C exhibited the improved optical and electrical performances, with a narrow band gap of 1.63 eV, an electrical resistivity of 1.3 × 10{sup 4} Ω cm, a carrier concentration of 7.3 × 10{sup 13} cm{sup −3} and a carrier mobility of 6.4 cm{sup 2} V{sup −1} s{sup −1}. This environmentally friendly synthetic route is promising for the preparation of high-quality Sb{sub 2}S{sub 3} films to be used as absorber layer materials for high-performance solar cells.

Demonstration of thin film pair distribution function analysis (tfPDF for the study of local structure in amorphous and crystalline thin films

Directory of Open Access Journals (Sweden)

Kirsten M. Ø. Jensen

2015-09-01

Full Text Available By means of normal-incidence, high-flux and high-energy X-rays, total scattering data for pair distribution function (PDF analysis have been obtained from thin films (tf, suitable for local structure analysis. By using amorphous substrates as support for the films, the standard Rapid Acquisition PDF setup can be applied and the scattering signal from the film can be isolated from the total scattering data through subtraction of an independently measured background signal. No angular corrections to the data are needed, as would be the case for grazing incidence measurements. The `tfPDF' method is illustrated through studies of as-deposited (i.e. amorphous and crystalline FeSb3 films, where the local structure analysis gives insight into the stabilization of the metastable skutterudite FeSb3 phase. The films were prepared by depositing ultra-thin alternating layers of Fe and Sb, which interdiffuse and after annealing crystallize to form the FeSb3 structure. The tfPDF data show that the amorphous precursor phase consists of corner-sharing FeSb6 octahedra with motifs highly resembling the local structure in crystalline FeSb3. Analysis of the amorphous structure allows the prediction of whether the final crystalline product will form the FeSb3 phase with or without excess Sb present. The study thus illustrates how analysis of the local structure in amorphous precursor films can help to understand crystallization processes of metastable phases and opens for a range of new local structure studies of thin films.

Co-sputtered ZnO:Si thin films as transparent conductive oxides

Energy Technology Data Exchange (ETDEWEB)

Faure, C. [CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F33600 Pessac (France); Clatot, J. [LRCS, 33 Rue St Leu, F-80039 Amiens (France); Teule-Gay, L.; Campet, G. [CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F33600 Pessac (France); Labrugere, C. [CeCaMA, Universite de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, Pessac, F-33608 (France); Nistor, M. [National Institute for Lasers, Plasmas and Radiation Physics, L22, PO Box MG-36, 77125 Bucharest-Magurele (Romania); Rougier, A., E-mail: rougier@icmcb-bordeaux.cnrs.fr [CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F33600 Pessac (France)

2012-12-01

Silicon doped Zinc Oxide thin films, so-called SZO, were deposited at room temperature on glass and plastic substrates by co-sputtering of ZnO and SiO{sub 2} targets. The influence of the SiO{sub 2} target power supply (from 30 to 75 W) on the SZO thin film composition and crystallinity is discussed. Si/Zn atomic ratio, determined by X-ray microprobe, increases from 1.2 to 8.2 at.%. For Si/Zn ratio equal and lower than 3.9%, SZO (S{sub 3.9}ZO) thin films exhibit the Wurzite structure with the (0 0 2) preferred orientation. Larger Si content leads to a decrease in crystallinity. With Si addition, the resistivity decreases down to 3.5 Multiplication-Sign 10{sup -3} Ohm-Sign {center_dot}cm for SZO thin film containing 3.9 at.% of Si prior to an increase. The mean transmittance of S{sub 3.9}ZO thin film on glass substrate approaches 80% (it is about 90% for the film itself) in the visible range (from 400 to 750 nm). Co-sputtered SZO thin films are suitable candidates for large area transparent conductive oxides. - Highlights: Black-Right-Pointing-Pointer Si doped ZnO thin films by co-sputtering of ZnO and SiO{sub 2} targets. Black-Right-Pointing-Pointer Minimum of resistivity for Si doped ZnO thin films containing 3.9% of Si. Black-Right-Pointing-Pointer Si and O environments by X-ray Photoelectron Spectroscopy.

The anomalous low temperature resistivity of thermally evaporated α-Mn thin film

International Nuclear Information System (INIS)

Ampong, F.K.; Boakye, F.; Nkum, R.K.

2010-01-01

Electrical resistivity measurements have been carried out on thermally evaporated α-Mn thin film between 300 and 1.4 K using the van der Pauw four probe technique. The film was grown on a glass substrate held at a temperature of 373 K, in an ambient pressure of 5x10 -6 Torr. The results show a resistance minimum, a notable characteristic of α-Mn but at a (rather high) temperature of 194±1 K. Below the resistivity maximum which corresponds to 70 K, the resistivity drops by only 0.02 μΩm indicating a rather short range magnetic ordering. The low temperature results show a tendency towards saturation of the resistivity as the temperature approaches zero suggesting a Kondo scattering.

The anomalous low temperature resistivity of thermally evaporated alpha-Mn thin film

Energy Technology Data Exchange (ETDEWEB)

Ampong, F.K., E-mail: kampxx@yahoo.co [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana); Boakye, F.; Nkum, R.K. [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana)

2010-08-15

Electrical resistivity measurements have been carried out on thermally evaporated alpha-Mn thin film between 300 and 1.4 K using the van der Pauw four probe technique. The film was grown on a glass substrate held at a temperature of 373 K, in an ambient pressure of 5x10{sup -6} Torr. The results show a resistance minimum, a notable characteristic of alpha-Mn but at a (rather high) temperature of 194+-1 K. Below the resistivity maximum which corresponds to 70 K, the resistivity drops by only 0.02 muOMEGAm indicating a rather short range magnetic ordering. The low temperature results show a tendency towards saturation of the resistivity as the temperature approaches zero suggesting a Kondo scattering.

Structural transformation of sputtered o-LiMnO{sub 2} thin-film cathodes induced by electrochemical cycling

Energy Technology Data Exchange (ETDEWEB)

Fischer, J., E-mail: Julian.Fischer@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials – Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Chang, K. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 52074 Aachen (Germany); Ye, J.; Ulrich, S.; Ziebert, C. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials – Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Music, D.; Hallstedt, B. [RWTH Aachen University, Materials Chemistry, Kopernikusstrasse 10, 52074 Aachen (Germany); Seifert, H.J. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials – Applied Materials Physics (IAM-AWP), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2013-12-31

Orthorhombic LiMnO{sub 2} (o-LiMnO{sub 2}) thin films were produced by non-reactive r.f. magnetron sputtering in combination with thermal post-annealing. Oxide phase formation was investigated by X-ray diffraction and Raman spectroscopy. In order to assign the X-ray signals and estimate the grain size, a simulation of the diffraction pattern was performed and compared with experimental data. The density of the films was determined to be 3.39 g/cm{sup 3} using X-ray reflectivity. Electrochemical characterization was carried out by galvanostatic cycling and cyclic voltammetry of Li/o-LiMnO{sub 2} half cells. There are distinct redox reactions at approx. 3 V and 4 V, whereas the latter splits into multiple peaks. Using ab initio calculations and thermodynamic models, Gibbs energies of o-LiMnO{sub 2} and c-LiMn{sub 2}O{sub 4} were determined. The relation between these energies explains the irreversible phase transformation that has been observed during the cycling of the Li/o-LiMnO{sub 2} half cell. - Highlights: • Quantitative, thermodynamic modeling of the o-LiMnO{sub 2}/c-LiMn{sub 2}O{sub 4} phase transformation • First CV-investigations on magnetron sputtered nanocrystalline o-LiMnO{sub 2} thin films • Synthesis of o-LiMnO{sub 2} planar model systems for protective coating and SEI development.

Molecular beam epitaxy growth of InSb_1-xBi_x thin films

DEFF Research Database (Denmark)

Yuxin Song; Shumin Wang; Saha Roy, Ivy

2013-01-01

Molecular beam epitaxy growth for InSb1-xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are stu...

Low temperature growth of Co{sub 2}MnSi films on diamond semiconductors by ion-beam assisted sputtering

Energy Technology Data Exchange (ETDEWEB)

Nishiwaki, M.; Ueda, K., E-mail: k-ueda@numse.nagoya-u.ac.jp; Asano, H. [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

2015-05-07

High quality Schottky junctions using Co{sub 2}MnSi/diamond heterostructures were fabricated. Low temperature growth at ∼300–400 °C by using ion-beam assisted sputtering (IBAS) was necessary to obtain abrupt Co{sub 2}MnSi/diamond interfaces. Only the Co{sub 2}MnSi films formed at ∼300–400 °C showed both saturation magnetization comparable to the bulk values and large negative anisotropic magnetoresistance, which suggests half-metallic nature of the Co{sub 2}MnSi films, of ∼0.3% at 10 K. Schottky junctions formed using the Co{sub 2}MnSi films showed clear rectification properties with rectification ratio of more than 10{sup 7} with Schottky barrier heights of ∼0.8 eV and ideality factors (n) of ∼1.2. These results indicate that Co{sub 2}MnSi films formed at ∼300–400 °C by IBAS are a promising spin source for spin injection into diamond semiconductors.

Domain wall conductivity in semiconducting hexagonal ferroelectric TbMnO3 thin films

International Nuclear Information System (INIS)

Kim, D J; Gruverman, A; Connell, J G; Seo, S S A

2016-01-01

Although enhanced conductivity of ferroelectric domain boundaries has been found in BiFeO 3 and Pb(Zr,Ti)O 3 films as well as hexagonal rare-earth manganite single crystals, the mechanism of the domain wall conductivity is still under debate. Using conductive atomic force microscopy, we observe enhanced conductance at the electrically-neutral domain walls in semiconducting hexagonal ferroelectric TbMnO 3 thin films where the structure and polarization direction are strongly constrained along the c-axis. This result indicates that domain wall conductivity in ferroelectric rare-earth manganites is not limited to charged domain walls. We show that the observed conductivity in the TbMnO 3 films is governed by a single conduction mechanism, namely, the back-to-back Schottky diodes tuned by the segregation of defects. (paper)

Codoping of Sb2Te3 thin films with V and Cr

Science.gov (United States)

Duffy, L. B.; Figueroa, A. I.; van der Laan, G.; Hesjedal, T.

2017-11-01

Magnetically doped topological insulators (TIs) are key to realizing the quantum anomalous Hall (QAH) effect, with the prospect of enabling dissipationless electronic devices in the future. Doping of the well-established three-dimensional TIs of the (Bi,Sb) 2(Se,Te) 3 family with the transition metals Cr and V is now an established approach for observing the QAH state at very low temperatures. While the magnetic transition temperatures of these materials are on the order of tens of degrees Kelvin, full quantization of the QAH state is achieved below ˜100 mK, governed by the size of the magnetic gap and thus the out-of-plane magnetic moment. In an attempt to raise the size of the magnetic moment and transition temperature, we carried out a structural and magnetic investigation of codoped (V,Cr):Sb2Te3 thin films. Starting from singly doped Cr:Sb2Te3 films, free of secondary phases and with a transition temperature of ˜72 K, we introduced increasing fractions of V and found a doubling of the transition temperature, while the magnetic moment decreases. In order to separate the properties and contributions of the two transition metals in the complex doping scenario independently, we employed spectroscopic x-ray techniques. Surprisingly, already small amounts of V lead to the formation of the secondary phase Cr2Te3 . No V was detectable in the Sb2Te3 matrix. Instead, it acts as a surfactant and can be found in the near-surface layers at the end of the growth. Our paper highlights the importance of x-ray-based studies for the doping of van der Waals systems, for which the optimization of magnetic moment or transition temperature alone is not necessarily a good strategy.

Above room temperature ferromagnetism in Si:Mn and TiO(2-delta)Co.

Science.gov (United States)

Granovsky, A; Orlov, A; Perov, N; Gan'shina, E; Semisalova, A; Balagurov, L; Kulemanov, I; Sapelkin, A; Rogalev, A; Smekhova, A

2012-09-01

We present recent experimental results on the structural, electrical, magnetic, and magneto-optical properties of Mn-implanted Si and Co-doped TiO(2-delta) magnetic oxides. Si wafers, both n- and p-type, with high and low resistivity, were used as the starting materials for implantation with Mn ions at the fluencies up to 5 x 10(16) cm(-2). The saturation magnetization was found to show the lack of any regular dependence on the Si conductivity type, type of impurity and the short post-implantation annealing. According to XMCD Mn impurity in Si does not bear any appreciable magnetic moment at room temperature. The obtained results indicate that above room temperature ferromagnetism in Mn-implanted Si originates not from Mn impurity but rather from structural defects in Si. The TiO(2-delta):Co thin films were deposited on LaAlO3 (001) substrates by magnetron sputtering in the argon-oxygen atmosphere at oxygen partial pressure of 2 x 10(-6)-2 x 10(-4) Torr. The obtained transverse Kerr effect spectra at the visible and XMCD spectra indicate on intrinsic room temperature ferromagnetism in TiO(2-delta):Co thin films at low (< 1%) volume fraction of Co.

Crystallization behavior of Ge-doped eutectic Sb70Te30 films in optical disks

International Nuclear Information System (INIS)

Khulbe, Pramod K.; Hurst, Terril; Mansuripur, Masud; Horie, Michikazu

2002-01-01

We report laser-induced crystallization behavior of binary Sb-Te and ternary Ge-doped eutectic Sb70Te30 thin film samples in a typical quadrilayer stack as used in phase-change optical disk data storage. Several experiments have been conducted on a two-laser static tester in which one laser operating in pulse mode writes crystalline marks on amorphous film or amorphous marks on crystalline film, while the second laser operating at low-power cw mode simultaneously monitors the progress of the crystalline or amorphous mark formation in real time in terms of the reflectivity variation. The results of this study show that the crystallization kinetics of this class of film is strongly growth dominant, which is significantly different from the crystallization kinetics of stochiometric Ge-Sb-Te compositions. In Sb-Te and Ge-doped eutectic Sb70Te30 thin-film samples, the crystallization behavior of the two forms of amorphous states, namely, as-deposited amorphous state and melt-quenched amorphous state, remains approximately same. We have also presented experiments showing the effect of the variation of the Sb/Te ratio and Ge doping on the crystallization behavior of these films

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.

Magnetic properties changes of MnAs thin films irradiated with highly charged ions

OpenAIRE

Trassinelli , Martino; Gafton , V.; Eddrief , Mahmoud; Etgens , Victor H.; Hidki , S.; Lacaze , Emmanuelle; Lamour , Emily; Luo , X.; Marangolo , Massimiliano; Merot , Jacques; Prigent , Christophe; Reuschl , Regina; Rozet , Jean-Pierre; Steydli , S.; Vernhet , Dominique

2013-01-01

International audience; We present the first investigation on the effect of highly charged ion bombardment on a manganese arsenide thin film. The MnAs films, 150~nm thick, are irradiated with 90 keV Ne$^{9+}$ ions with a dose varying from $1.6\\times10^{12}$ to $1.6\\times10^{15}$~ions/cm$^2$. The structural and magnetic properties of the film after irradiation are investigated using different techniques, namely, X-ray diffraction, magneto-optic Kerr effect and magnetic force microscope. Prelim...

A highly selective and wide range ammonia sensor—Nanostructured ZnO:Co thin film

International Nuclear Information System (INIS)

Mani, Ganesh Kumar; Rayappan, John Bosco Balaguru

2015-01-01

Graphical abstract: - Highlights: • Cobalt doped nanostructured ZnO thin films were spray deposited on glass substrates. • Co-doped ZnO film was highly selective towards ammonia than ethanol, methanol, etc. • The range of ammonia detection was improved significantly by doping cobalt in ZnO. - Abstract: Ammonia sensing characteristics of undoped and cobalt (Co)-doped nanostructured ZnO thin films were investigated. Polycrystalline nature with hexagonal wurtzite structure and high crystalline quality with dominant (0 0 2) plane orientation of Co-doped ZnO film were confirmed by the X-ray diffractogram. Scanning electron micrographs of the undoped film demonstrated the uniform deposition of sphere-shaped grains. But, smaller particles with no clear grain boundaries were observed for Co-doped ZnO thin film. Band gap values were found to be 3.26 eV and 3.22 eV for undoped and Co-doped ZnO thin films. Ammonia sensing characteristics of Co-doped ZnO film at room temperature were investigated in the concentration range of 15–1000 ppm. Variation in the sensing performances of Co-doped and pure ZnO thin films has been analyzed and compared

Electronic transport properties of nanostructured MnSi-films

Science.gov (United States)

Schroeter, D.; Steinki, N.; Scarioni, A. Fernández; Schumacher, H. W.; Süllow, S.; Menzel, D.

2018-05-01

MnSi, which crystallizes in the cubic B20 structure, shows intriguing magnetic properties involving the existence of skyrmions in the magnetic phase diagram. Bulk MnSi has been intensively investigated and thoroughly characterized, in contrast to MnSi thin film, which exhibits widely varying properties in particular with respect to electronic transport. In this situation, we have set out to reinvestigate the transport properties in MnSi thin films by means of studying nanostructure samples. In particular, Hall geometry nanostructures were produced to determine the intrinsic transport properties.

Thickness and temperature dependence of electrical resistivity of p-type Bi0.5Sb1.5Te3 thin films prepared by flash evaporation method

International Nuclear Information System (INIS)

Duan Xingkai; Yang Junyou; Zhu, W; Fan, X A; Bao, S Q

2006-01-01

P-type Bi 0.5 Sb 1.5 Te 3 thin films with thicknesses in the range 80-320 nm have been deposited by the flash evaporation method on glass substrates at 473 K. XRD and field emission scanning electron microscope were performed to characterize the thin films. The results show that the thin films are polycrystalline and the grain size of the thin films increases with increasing thickness of the thin films. Compositional analysis of the thin films was also carried out by energy-dispersive x-ray analysis. A near linear relationship was observed between the electrical resistivity and the inverse thickness of the annealed thin films, and it agrees with Tellier's model. Electrical resistivity of the annealed thin films was studied in the temperature range 300-350 K, and their thermal activation behaviour was characterized, the activation energy for conduction decreases with increasing thickness of the thin films

Enhanced moments in bcc Co{sub 1−x}Mn{sub x} on MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Snow, R.J.; Bhatkar, H. [Department of Physics, Montana State University, Bozeman, MT 59715 (United States); N' Diaye, A.T.; Arenholz, E. [Advanced Light Source, Lawrence Berkeley Nat. Labs, Berkeley, CA 94720 (United States); Idzerda, Y.U., E-mail: Idzerda@montana.edu [Department of Physics, Montana State University, Bozeman, MT 59715 (United States)

2016-12-01

A 40% enhancement of the Co magnetic moment has been found for thin films of bcc Co{sub 1−x}Mn{sub x} grown by molecular beam epitaxy on a 2 nm bcc Fe buffer layer on MgO(001). Although the bcc phase cannot be stabilized in the bulk, we confirm that it is stable as an epitaxial film in the composition range x=0–0.7. Using X-ray absorption spectroscopy and X-ray magnetic circular dichroism, we show that the Co moment is a maximum of 2.38 μ{sub B} at x=0.24, while the net Mn moment remains roughly constant until x=0.24, then drops steadily. Mn is found to align parallel with Co for all ferromagnetic concentrations, up to x=0.7, where the total moment of the film abruptly collapses to zero, most likely due to the onset of the observed structural instability. - Highlights: • Stabilization of bcc Co{sub 1−x}Mn{sub x} films in the composition range of x=0 to 0.7. • Enhancement of Co moment by 40% from pure bcc Co. • Parallel alignment of Mn moment and Co moment. • Measured the elemental moment of Co and Mn as a function of composition.

Stress analysis, structure and magnetic properties of sputter deposited Ni-Mn-Ga ferromagnetic shape memory thin films

Energy Technology Data Exchange (ETDEWEB)

Annadurai, A. [Department of Physics, PSG College of Technology, Coimbatore 641004 (India); Manivel Raja, M., E-mail: mraja@dmrl.drdo.in [Defense Metallurgical Research Laboratory, Hyderabad 500058 (India); Prabahar, K.; Kumar, Atul [Defense Metallurgical Research Laboratory, Hyderabad 500058 (India); Kannan, M.D.; Jayakumar, S. [Department of Physics, PSG College of Technology, Coimbatore 641004 (India)

2011-11-15

The residual stress instituted in Ni-Mn-Ga thin films during deposition is a key parameter influencing their shape memory applications by affecting its structural and magnetic properties. A series of Ni-Mn-Ga thin films were prepared by dc magnetron sputtering on Si(1 0 0) and glass substrates at four different sputtering powers of 25, 45, 75 and 100 W for systematic investigation of the residual stress and its effect on structure and magnetic properties. The residual stresses in thin films were characterized by a laser scanning technique. The as-deposited films were annealed at 600 deg. C for 1 h in vacuum for structural and magnetic ordering. The compressive stresses observed in as-deposited films transformed into tensile stresses upon annealing. The annealed films were found to be crystalline and possess mixed phases of both austenite and martensite, exhibiting good soft magnetic properties. It was found that the increase of sputtering power induced coarsening in thin films. Typical saturation magnetization and coercivity values were found to be 330 emu/cm{sup 3} and 215 Oe, respectively. The films deposited at 75 and 100 W display both structural and magnetic transitions above room temperature. - Highlights: > Compressive stresses observed in as-deposited films transformed into tensile stresses upon annealing. > Annealed films were found to be crystalline and possess mixed phases of both austenite and martensite, exhibiting good soft magnetic properties. > The highest Curie transition in the films was observed at 365 K. > The films deposited at 75 and 100 W display both structural and magnetic transitions above room temperature.

A comparative investigation on structure and multiferroic properties of bismuth ferrite thin films by multielement co-doping

Energy Technology Data Exchange (ETDEWEB)

Dong, Guohua; Tan, Guoqiang, E-mail: tan3114@163.com; Luo, Yangyang; Liu, Wenlong; Xia, Ao; Ren, Huijun

2014-12-15

Highlights: • Multielement (Tb, Cr and Mn) co-doped BiFeO{sub 3} films were fabricated by CSD method. • Multielement co-doping induces a structural transition. • It is found effective to stabilize the valence of Fe ions at +3 by the strategy. • The co-doping at A/B-sites gives rise to the superior multiferroic properties. - Abstract: (Tb, Cr and Mn) multielement co-doped BiFeO{sub 3} (BTFCMO) thin films were prepared by the chemical solution deposition method on fluorine doped tin oxide (FTO) substrates. X-ray diffraction, Rietveld refinement and Raman analyses revealed that a phase transition from rhombohedral to triclinic structure occurs in the multielement co-doped BiFeO{sub 3} films. It is found that the doping is conducive to stabilizing the valence of Fe ions and reducing leakage current. In addition, the highly enhanced ferroelectric properties with a huge remanent polarization (2P{sub r}) of 239.6 μC/cm{sup 2} and a low coercive field (2E{sub c}) of 615.6 kV/cm are ascribed to the well film texture, the structure transition and the reduced leakage current by the co-doping. Moreover, the structure transition is the dominant factor resulting in the significant enhancement observed in magnetization (M{sub s} ∼ 10.5 emu/cm{sup 3}), owing to the collapse of the space-modulated spin structure. In this contribution, these results demonstrate that the multielement co-doping is in favor of the enhanced multiferroic properties of the BFO films for possible multifunctional applications.

Effect of visible light on the optical properties of a-(Ge2Sb2Te5)90Ag10 thin film

Science.gov (United States)

Singh, Palwinder; Thakur, Anup

2018-05-01

(Ge2Sb2Te5)90Ag10 (GST-Ag) bulk alloy was prepared using melt quenching technique. GST-Ag thin film was deposited on glass substrate using thermal evaporation method. The prepared thin films were exposed to visible light (intensity of 105 Lux for 2, 8, 20 and 30 hours) using 25W LED lamp. Transmission spectra were taken using UV-vis-NIR spectrophotometer in the wavelength range 800-3200 nm. Optical band gap of as-deposited and light exposed thin films was determined using Tauc's plot. Optical band gap was found to be decreasing on light exposure upto 8 hours and after that no significant change was observed.

Physical processes in thin-film electroluminescent structures based on ZnS:Mn showing self-organized patterns

International Nuclear Information System (INIS)

Zuccaro, S.; Raker, Th.; Niedernostheide, F.-J.; Kuhn, T.; Purwins, H.-G.

2003-01-01

Physical processes in thin ZnS:Mn films and their relation to the formation of dynamical patterns in the electroluminescence of AC driven films are investigated. The technique of photo-depolarization-spectroscopy is used to investigate defect states in these films and it is shown that specific features in the spectra correlate with the observed self-organized patterns. Furthermore, the time dependence of the dissipative current is measured at the same samples and compared with current waveforms obtained from numerical simulations of a drift-diffusion model. The results are used to discuss the origin of the self-organized processes in ZnS:Mn-films

Device design of GaSb/CdS thin film thermal photovoltaic solar cells%基于GaSb/CdS薄膜热光伏电池的器件设计∗

Institute of Scientific and Technical Information of China (English)

吴限量; 张德贤; 蔡宏琨; 周严; 倪牮; 张建军

2015-01-01

基于GaSb薄膜热光伏器件是降低热光伏系统成本的有效途径之一，本文主要针对GaSb/CdS薄膜热光伏器件结构进行理论分析.采用AFORS-HET软件进行模拟仿真，分析GaSb和CdS两种材料各自的缺陷态密度、界面态对电池性能的影响.根据软件模拟可以得知，吸收层GaSb的缺陷态密度以及GaSb与CdS之间的界面态密度是影响电池性能的重要因素.当GaSb缺陷态增加时，主要影响电池的填充因子，电池效率明显下降.而作为窗口层的CdS缺陷态密度对电池性能影响不明显，当CdS缺陷态密度上升4个数量级时，电池效率仅下降0.11%.%Enthusiasm in the research of thermo-photovoltaic (TPV) cells has been aroused because the low bandwidth semi-conductors of III-V family are coming into use. GaSb, as a member of III-V family, has many merits such as high absorption coeffcient, and low band gap of 0.725 eV at 300 K etc.. At present thermo-photovoltaic cells are usually based on GaSb wafer, and it can be manufactured by the vertical Bridgeman method. Thermo-photovoltaic cell based on GaSb films is one of the effective ways to reduce the cost of the thermo-photovoltaic system. GaSb polycrystalline films can be grown by physical vapor deposition (PVD) which has advantages in using fewer materials and energy, and also in doing little harm to the environment. Because of residual acceptor defects VGaGaSb, GaSb thin film is usually of p-type semiconductor. So we should find n-type semiconductor material to form pn junction. We choose CdS as the emission layer of a cell structure. CdS belongs to n-type semiconductor with a narrow band gap of 2.4 eV and high light transmissivity. CdS thin film grown by chemical bath deposition (CBD) has passivation properties for GaSb. CdS layers can remove native oxides from GaSb surface and reduce the surface recombination velocity of GaSb. This paper focuses on theoretical analysis of GaSb/CdS thin film photovoltaic

Effect of doping concentration on the structural, morphological, optical and electrical properties of Mn-doped CdO thin films

Directory of Open Access Journals (Sweden)

Manjula N.

2015-12-01

Full Text Available Thin films of manganese-doped cadmium oxide (CdO:Mn with different Mn-doping levels (0, 1, 2, 3 and 4 at.% were deposited on glass substrates by employing an inexpensive, simplified spray technique using a perfume atomizer at 375 °C. The influence of Mn incorporation on the structural, morphological, optical and electrical properties of CdO films has been studied. All the films exhibit cubic crystal structure with a (1 1 1 preferential orientation. Mn-doping causes a slight shift of the (1 1 1 diffraction peak towards higher angle. The crystallite size of the films is found to decrease from 34.63 nm to 17.68 nm with an increase in Mn doping concentration. The CdO:Mn film coated with 1 at.% Mn exhibit a high transparency of nearly 90 % which decreases for higher doping concentration. The optical band gap decreases with an increase in Mn doping concentration. All the films have electrical resistivity of the order of 10−4 Ω·cm.

Effect of Cr addition on the structural, magnetic and mechanical properties of magnetron sputtered Ni-Mn-In ferromagnetic shape memory alloy thin films

Energy Technology Data Exchange (ETDEWEB)

Akkera, Harish Sharma [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Lab, Department of Physics, Roorkee, Uttarakhand (India); Madanapalle Institute of Technology and Science, Department of Physics, Madanapalle, Chittoor, Andhra Pradesh (India); Kaur, Davinder [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Lab, Department of Physics, Roorkee, Uttarakhand (India)

2016-12-15

The effect of Cr substitution for In on the structural, martensitic phase transformation and mechanical properties of Ni-Mn-In ferromagnetic shape memory alloy (FSMA) thin films was systematically investigated. X-ray diffraction results revealed that the Ni-Mn-In-Cr thin films possessed purely austenitic cubic L2{sub 1} structure at lower content of Cr, whereas higher Cr content, the Ni-Mn-In-Cr thin films exhibited martensitic structure at room temperature. The temperature-dependent magnetization (M-T) and resistance (R-T) results confirmed that the monotonous increase in martensitic transformation temperatures (T{sub M}) with the addition of Cr content. Further, the room temperature nanoindentation studies revealed the mechanical properties such as hardness (H), elastic modulus (E), plasticity index (H/E) and resistance to plastic deformation (H{sup 3}/E {sup 2}) of all the samples. The addition of Cr content significantly enhanced the hardness (28.2 ± 2.4 GPa) and resistance to plastic deformation H{sup 3}/E{sup 2} (0.261) of Ni{sub 50.4}Mn{sub 34.96}In{sub 13.56}Cr{sub 1.08} film as compared with pure Ni-Mn-In film. As a result, the appropriate addition of Cr significantly improved the mechanical properties with a decrease in grain size, which could be further attributed to the grain boundary strengthening mechanism. These findings indicate that the Cr-doped Ni-Mn-In FSMA thin films are potential candidates for microelectromechanical systems applications. (orig.)

Magnetic structure of the YbMn2SbBi compound

International Nuclear Information System (INIS)

Morozkin, A.V.; Manfrinetti, P.

2011-01-01

Graphical abstract: Display Omitted Research highlights: → A neutron diffraction investigation in zero applied field of La 2 O 2 S-type YbMn 2 SbBi shows antiferromagnetic ordering below 138(3) K and ferrimagnetic ordering below 112(3) K. → Between 138 and 112 K, the magnetic structure of YbMn 2 SbBi consists of antiferromagnetically coupled ab-plane magnetic moments of the manganese atoms (D 1d magnetic point group). → Below 112(3) K, the magnetic structure of YbMn 2 SbBi becames the sum antiferromagnetic component with D 1d magnetic point group and ferromagnetic one with C 2 magnetic point group. → The magnitude of Yb and Mn magnetic moments in YbMn 2 SbBi at 2 K (M Yb = 3.6(2) μ B , M Mn = 3.5(2) μ B ) correspond to the trivalent state of the Yb ions and tetravalent state of the Mn ions. - Abstract: A neutron diffraction investigation has been carried out on the trigonal La 2 O 2 S-type (hP5, space group P3-bar ml, No. 164; also CaAl 2 Si 2 -type) YbMn 2 SbBi intermetallic compound. The YbMn 2 SbBi presents antiferromagnetic ordering below 138(3) K and ferrimagnetic ordering below 112(3) K. Between 138 and 112 K, the magnetic structure of YbMn 2 SbBi consists of antiferromagnetically coupled ab-plane magnetic moments of the manganese atoms (D 1d magnetic point group). Below 112(3) K, the ferromagnetic components of Yb and Mn begin to develop, and the magnetic structure of YbMn 2 SbBi becames the sum antiferromagnetic component with D 1d magnetic point group and ferromagnetic one with C 2 magnetic point group. The magnitude of Yb and Mn magnetic moments in YbMn 2 SbBi at 2 K (M Yb = 3.6(2) μ B , M Mn = 3.5(2) μ B ) correspond to the trivalent state of the Yb ions and tetravalent state of the Mn ions.

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

International Nuclear Information System (INIS)

Shaji, S.; Garcia, L.V.; Loredo, S.L.; Krishnan, B.

2017-01-01

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb_2S_3) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb_2S_3 thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb_2S_3 thin films for optoelectronic applications.

Antimony sulfide thin films prepared by laser assisted chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Garcia, L.V. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); Loredo, S.L. [Centro de Investigación en Materiales Avanzados (CIMAV), Unidad Monterrey, PIIT, Apodaca, Nuevo León (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); and others

2017-01-30

Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb{sub 2}S{sub 3}) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb{sub 2}S{sub 3} thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb{sub 2}S{sub 3} thin films for optoelectronic applications.

Preparation of electrochromic thin films by transformation of manganese(II) carbonate

Science.gov (United States)

Stojkovikj, Sasho; Najdoski, Metodija; Koleva, Violeta; Demiri, Sani

2013-10-01

A new chemical bath method for deposition of manganese(II) carbonate thin film on electroconductive FTO glass substrates is designed. The homogeneous thin films with thickness in the range of 70 to 500 nm are deposited at about 98 °C from aqueous solution containing urea and MnCl2. The chemical process is based on a low temperature hydrolysis of the manganese complexes with urea. Three types of films are under consideration: as-deposited, annealed and electrochemically transformed thin films. The structure of the films is studied by XRD, IR and Raman spectroscopy. Electrochemical and optical properties are examined in eight different electrolytes (neutral and alkaline) and the best results are achieved in two component aqueous solution of 0.1 M KNO3 and 0.01 M KOH. It is established that the as-deposited MnCO3 film undergoes electrochemically transformation into birnessite-type manganese(IV) oxide films, which exhibit electrochromic color changes (from bright brown to pale yellow and vice versa) with 30% difference in the transmittance of the colored and bleached state at 400 nm.

Magneto-transport and thermoelectric properties of epitaxial FeSb{sub 2} thin film on MgO substrate

Energy Technology Data Exchange (ETDEWEB)

Duong, Anh Tuan; Rhim, S. H., E-mail: sonny@ulsan.ac.kr; Shin, Yooleemi; Nguyen, Van Quang; Cho, Sunglae, E-mail: slcho@ulsan.ac.kr [Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749 (Korea, Republic of)

2015-01-19

We report magneto-transport and thermoelectric properties of FeSb{sub 2} thin film epitaxially grown on the MgO substrate using molecular beam epitaxy. The film exhibits compressive strain of 1.74% owing to large lattice mismatch, whose physical consequences are nontrivial. Magnetic phase has been changed from diamagnetic in bulk, as evidenced by anomalous Hall effect (AHE) and negative magneto-resistance (MR). The FeSb{sub 2} film is semiconducting without any metallic transition unlike the bulk counterpart. In particular, hysteresis in MR with distinct feature of AHE is evident with coercive field of 500 and 110 Oe for T = 20 and 50 K, respectively. Furthermore, from the Seebeck coefficients and temperature dependence of the resistivity, it is evident that the film is semiconducting with small band gap: 3.76 meV for T < 40 K and 13.48 meV for T > 40 K, respectively, where maximum thermoelectric power factor of 12 μV/cm·K at T = 50 K.

Anomalous aging and strain induced time dependent phenomena in ultra-thin La0.65Ca0.35MnO3 films

International Nuclear Information System (INIS)

Egilmez, M.; Saber, M.M.; Abdelhadi, M.; Chow, K.H.; Jung, J.

2011-01-01

We have shown that ultra-thin La 0.65 Ca 0.35 MnO 3 films exhibit strong metastable behavior. The resistance can vary with time significantly, suggesting that a state of dynamic phase separation exists whereby one phase grows at the expense of another. Physical properties associated with the metastable behavior have been investigated on the films grown on different substrates. We have found that ultra-thin films age much faster than the thicker counterparts and more interestingly the metastability in the resistance of these films enhanced when aged. -- Highlights: → Ultra-thin La 0.67 Ca 0.33 MnO 3 films exhibit metastable behavior. → Physical properties associated with metastable behavior have been investigated. → The metastability in resistance of the films enhanced when films are aged. → Relaxation rates were used as a relative measure the metastability. → The metastable behavior is sensitive to the strain state of the film.

Nanometric thin film membranes manufactured on square meter scale: ultra-thin films for CO 2 capture

KAUST Repository

Yave, Wilfredo

2010-09-01

Miniaturization and manipulation of materials at nanometer scale are key challenges in nanoscience and nanotechnology. In membrane science and technology, the fabrication of ultra-thin polymer films (defect-free) on square meter scale with uniform thickness (<100 nm) is crucial. By using a tailor-made polymer and by controlling the nanofabrication conditions, we developed and manufactured defect-free ultra-thin film membranes with unmatched carbon dioxide permeances, i.e. >5 m3 (STP) m-2 h -1 bar-1. The permeances are extremely high, because the membranes are made from a CO2 philic polymer material and they are only a few tens of nanometers thin. Thus, these thin film membranes have potential application in the treatment of large gas streams under low pressure like, e.g., carbon dioxide separation from flue gas. © 2010 IOP Publishing Ltd.

Growth of LiMn{sub 2}O{sub 4} thin films by pulsed-laser deposition and their electrochemical properties in lithium microbatteries

Energy Technology Data Exchange (ETDEWEB)

Julien, C. [Univ. Pierre et Marie Curie, Paris (France). LMDH; Haro-Poniatowski, E. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico); Camacho-Lopez, M.A. [LMDH, UMR 7603, Universite Pierre et Marie Curie, 4 place Jussieu, 75252, Paris (France); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico (Mexico); Jimenez-Jarquin, J. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico)

2000-03-01

Films of LiMn{sub 2}O{sub 4} were grown by pulsed-laser deposition (PLD) onto silicon wafers using sintered targets which consisted in the mixture of LiMn{sub 2}O{sub 4} and Li{sub 2}O powders. The film formation has been studied as a function of the preparation conditions, i.e. composition of the target, substrate temperature, and oxygen partial pressure in the deposition chamber. Composition, morphology and structural properties of PLD films have been investigated using Rutherford backscattering spectroscopy, scanning electron microscopy, X-ray diffraction and Raman scattering spectroscopy. The films deposited from target LiMn{sub 2}O{sub 4}+15% Li{sub 2}O have an excellent crystallinity when deposited onto silicon substrate maintained at 300 C in an oxygen partial pressure of 100 mTorr. It is found that such a film crystallizes in the spinel structure (Fd3m symmetry) as evidenced by X-ray diffraction. Well-textured polycrystalline films exhibit crystallite size of 300 nm. Pulsed-laser deposited LiMn{sub 2}O{sub 4} thin films obtained with a polycrystalline morphology were successfully used as cathode materials in lithium microbatteries. The Li//LiMn{sub 2}O{sub 4} thin film cells have been tested by cyclic voltammetry and galvanostatic charge-discharge techniques in the potential range 3.0-4.2 V. Specific capacity as high as 120 mC/cm{sup 2} {mu}m was measured on polycrystalline films. The chemical diffusion coefficients for the Li{sub x}Mn{sub 2}O{sub 4} thin films appear to be in the range of 10{sup -11}-10{sup -12} cm{sup 2}/s. Electrochemical measurements show a good cycleability of PLD films when cells are charged-discharged at current densities of 5-25 {mu}A/cm{sup 2}. (orig.)

On the Novel Biaxial Strain Relaxation Mechanism in Epitaxial Composition Graded La1−xSrxMnO3 Thin Film Synthesized by RF Magnetron Sputtering

Directory of Open Access Journals (Sweden)

Yishu Wang

2015-11-01

Full Text Available We report on a novel method to fabricate composition gradient, epitaxial La1−xSrxMnO3 thin films with the objective to alleviate biaxial film strain. In this work, epitaxial, composition gradient La1−xSrxMnO3, and pure LaMnO3 and La0.67Sr0.33MnO3 thin films were deposited by radio frequency (RF magnetron sputtering. The crystalline and epitaxy of all films were first studied by symmetric θ–2θ X-ray diffraction (XRD and low angle XRD experiments. Detailed microstructural characterization across the film thickness was conducted by high-resolution transmission electron microscopy and electron diffraction. Four compositional gradient domains were observed in the La1−xSrxMnO3 film ranging from LaMnO3 rich to La0.67Sr0.33MnO3 at the surface. A continuous reduction in the lattice parameter was observed accompanied by a significant reduction in the out-of-plane strain in the film. Fabrication of the composition gradient La1−xSrxMnO3 thin film was found to be a powerful method to relieve biaxial strain under critical thickness. Besides, the coexistence of domains with a composition variance is opening up various new possibilities of designing new nanoscale structures with unusual cross coupled properties.

Structural evolution of bias sputtered LiNi0.5Mn1.5O4 thin film cathodes for lithium ion batteries

International Nuclear Information System (INIS)

Su, Shih-Hsuan; Chiu, Kuo-Feng; Leu, Hoang-Jyh

2014-01-01

LiNi 0.5 Mn 1.5 O 4 (LNMO) thin films have been deposited on stainless steel substrates using radio frequency (f = 13.56 MHz) magnetron sputtering, followed by thermal annealing in ambient atmosphere. Various negative biases were applied on the substrates during deposition. The structural evolution of LNMO thin films under different negative biases has been investigated and characterized by X-ray diffraction. All of the deposited films exhibit a crystalline spinel structure with a space group of Fd-3m, which is a so-called disordered phase. The results also indicate that particle size decreases with increasing negative bias. The electrochemical properties of the LNMO thin films as cathode materials for lithium ion batteries were investigated. Two distinctive voltage plateaus at ∼ 4.7 V and at ∼ 4.0 V (vs. Li + /Li) can be observed in the discharge curves, corresponding to the reactions of the disordered phase. The capacity of LNMO thin film electrodes under suitable negative bias can be optimized. - Highlights: • LiNi 0.5 Mn 1.5 O 4 thin films have been deposited on stainless steel substrates. • Various negative biases were applied on the substrates during deposition. • The particle sizes of LNMO thin films decrease with increasing negative bias

A comparative study of the physical properties of Sb2S3 thin films treated with N2 AC plasma and thermal annealing in N2

International Nuclear Information System (INIS)

Calixto-Rodriguez, M.; Martinez, H.; Pena, Y.; Flores, O.; Esparza-Ponce, H.E.; Sanchez-Juarez, A.; Campos-Alvarez, J.; Reyes, P.

2010-01-01

As-deposited antimony sulfide thin films prepared by chemical bath deposition were treated with nitrogen AC plasma and thermal annealing in nitrogen atmosphere. The as-deposited, plasma treated, and thermally annealed antimony sulfide thin films have been characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, UV-vis spectroscopy, and electrical measurements. The results have shown that post-deposition treatments modify the crystalline structure, the morphology, and the optoelectronic properties of Sb 2 S 3 thin films. X-ray diffraction studies showed that the crystallinity of the films was improved in both cases. Atomic force microscopy studies showed that the change in the film morphology depends on the post-deposition treatment used. Optical emission spectroscopy (OES) analysis revealed the plasma etching on the surface of the film, this fact was corroborated by the energy dispersive X-ray spectroscopy analysis. The optical band gap of the films (E g ) decreased after post-deposition treatments (from 2.36 to 1.75 eV) due to the improvement in the grain sizes. The electrical resistivity of the Sb 2 S 3 thin films decreased from 10 8 to 10 6 Ω-cm after plasma treatments.

Electrical and structural properties of La0.8Sr0.2Mn0.5Co0.5O3±δ films produced by pulsed laser deposition

DEFF Research Database (Denmark)

Pryds, Nini; Christensen, Bo Toftmann; Schou, Jørgen

2005-01-01

La0.8Sr0.2Mn0.5Co0.5O3 (LSMCO) films for the use as contact layers or protective coatings in solid oxide fuel cells (SOFC) have been deposited on glass substrates by pulsed laser deposition (PLD). PLD is an obvious technique for thin film production of complex oxides, because of the ability...

High absorption coefficients of the CuSb(Se,Te2 and CuBi(S,Se2 alloys enable high-efficient 100 nm thin-film photovoltaics

Directory of Open Access Journals (Sweden)

Chen Rongzhen

2017-01-01

Full Text Available We demonstrate that the band-gap energies Eg of CuSb(Se,Te2 and CuBi(S,Se2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1−xTex2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω for CuSb(Se1−xTex2 is at ħω = Eg + 1 eV as much as 5–7 times larger than α(ω for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 − 150 nm, and the efficiency increases to ∼30% if the Auger effect is diminished.

High absorption coefficients of the CuSb(Se,Te)2 and CuBi(S,Se)2 alloys enable high-efficient 100 nm thin-film photovoltaics

Science.gov (United States)

Chen, Rongzhen; Persson, Clas

2017-06-01

We demonstrate that the band-gap energies Eg of CuSb(Se,Te)2 and CuBi(S,Se)2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1-xTex)2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω) for CuSb(Se1-xTex)2 is at ħω = Eg + 1 eV as much as 5-7 times larger than α(ω) for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 - 150 nm, and the efficiency increases to ˜30% if the Auger effect is diminished.

Surface and magnetic characteristics of Ni-Mn-Ga/Si (100) thin film

Energy Technology Data Exchange (ETDEWEB)

Kumar, S. Vinodh; Pandyan, R. Kodi; Mahendran, M., E-mail: manickam-mahendran@tce.edu, E-mail: perialangulam@gmail.com [Smart Materials Lab, Department of Physics, Thiagarajar College of Engineering, Madurai – 625 015 (India); Raja, M. Manivel [Defence Metallurgical Research Laboratory, Hyderabad – 500 058 (India); Pandi, R. Senthur [School of Advanced Sciences, VIT University, Vellore – 632 014 (India)

2016-05-23

Polycrystalline Ni-Mn-Ga thin films have been deposited on Si (100) substrate with different film thickness. The influence of film thickness on the phase structure and magnetic domain of the films has been examined by scanning electron microscope, atomic force microscopy and magnetic force microscopy. Analysis of structural parameters indicates that the film at lower thickness exhibits the coexistence of both austenite and martensite phase, whereas at higher thickness L1{sub 2} cubic non magnetic phase is noticed. The grains size and the surface roughness increase along with the film thickness and attain the maximum of 45 nm and 34.96 nm, respectively. At lower film thickness, the magnetic stripe domain is found like maze pattern with dark and bright images, while at higher thickness the absence of stripe domains is observed. The magnetic results reveal that the films strongly depend on their phase structure and microstructure which influence by the film thickness.

Properties of antimony doped ZnO thin films deposited by spray pyrolysis technique

Energy Technology Data Exchange (ETDEWEB)

Sadananda Kumar, N., E-mail: sadanthara@gmail.com; Bangera, Kasturi V.; Shivakumar, G. K. [National Institute of Technology Karnataka, Surathkal, Thin Films Laboratory, Department of Physics (India)

2015-07-15

Antimony (Sb) doped zinc oxide (ZnO) thin films were deposited on the glass substrate at 450°C using spray pyrolysis technique. Effect of Sb doping on surface morphology structural, optical and electrical properties were studied. X-ray diffraction (XRD) analysis showed that both the undoped and doped ZnO thin films are polycrystalline in nature with (101) preferred orientation. SEM analysis showed a change in surface morphology of Sb doped ZnO thin films. Doping results in a marked increase in conductivity without affecting the transmittance of the films. ZnO films prepared with 3 at % Sb shows the lowest resistivity of 0.185 Ohm cm with a Hall mobility of 54.05 cm{sup 2} V{sup –1} s{sup –1}, and a hole concentration of 6.25 × 10{sup 17} cm{sup –3}.

Characteristics of rapid-thermal-annealed LiCoO2 cathode film for an all-solid-state thin film microbattery

International Nuclear Information System (INIS)

Kim, Han-Ki; Yoon, Young Soo

2004-01-01

We report on the fabrication of a LiCoO 2 film for an all-solid-state thin film microbattery by using a rapid-thermal-annealing (RTA) process. The LiCoO 2 films were grown by rf magnetron sputtering using a synthesized LiCoO 2 target in a [O 2 /(Ar+O 2 )] ratio of 10%. Scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) analysis results showed that the surface layer on the as-deposited LiCoO 2 film was completely removed by rapid thermal annealing process in oxygen ambient for 20 min. In addition, the thin film microbattery fabricated with the annealed LiCoO 2 film shows fairly stable cyclability with a specific discharge capacity of 56.49 μAh/cm2 μm. These results show the possibility of the RTA LiCoO 2 film and rapid thermal annealing process being a promising cathode material and annealing process for thin film microbatteries, respectively

Refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films by multiple femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Lei, Kai; Wang, Yang, E-mail: ywang@siom.ac.cn; Jiang, Minghui; Wu, Yiqun [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2016-05-07

In this study, the controllable effective refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.

Narrow-band tunable terahertz emission from ferrimagnetic Mn{sub 3-x}Ga thin films

Energy Technology Data Exchange (ETDEWEB)

Awari, N. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); University of Groningen, 9747 AG Groningen (Netherlands); Kovalev, S., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Fowley, C., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Green, B.; Yildirim, O.; Lindner, J.; Fassbender, J.; Deac, A. M.; Gensch, M. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); Rode, K., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Lau, Y.-C.; Betto, D.; Thiyagarajah, N.; Coey, J. M. D. [CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Gallardo, R. A. [Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123 Valparíso (Chile)

2016-07-18

Narrow-band terahertz emission from coherently excited spin precession in metallic ferrimagnetic Mn{sub 3-x}Ga Heusler alloy nanofilms has been observed. The efficiency of the emission, per nanometer film thickness, is comparable or higher than that of classical laser-driven terahertz sources based on optical rectification. The center frequency of the emission from the films can be tuned precisely via the film composition in the range of 0.20–0.35 THz, making this type of metallic film a candidate for efficient on-chip terahertz emitters. Terahertz emission spectroscopy is furthermore shown to be a sensitive probe of magnetic properties of ultra-thin films.

Highly polarized single-c-domain single-crystal Pb(Mn,Nb)O(3)-PZT thin films.

Science.gov (United States)

Wasa, Kiyotaka; Adachi, Hideaki; Nishida, Ken; Yamamoto, Takashi; Matsushima, Tomoaki; Kanno, Isaku; Kotera, Hidetoshi

2012-01-01

In-plane unstrained single-c-domain/single-crystal thin films of PZT-based ternary ferroelectric perovskite, ξPb(Mn,Nb)O3-(1 - ξ)PZT, were grown on SrRuO(3)/Pt/MgO substrates using magnetron sputtering followed by quenching. The sputtered unstrained thin films exhibit unique ferroelectric properties: high coercive field, Ec > 180 kV/cm, large remanent polarization, P(r) = 100 μC/cm(2), small relative dielectric constants, ε* = 100 to 150, high Curie temperature, Tc = ~600 °C, and bulk-like large transverse piezoelectric constants, e31,f = -12.0 C/m(2) for PZT(48/52) at ξ = 0.06. The unstrained thin films are an ideal structure to extract the bulk ferroelectric properties. Their micro-structures and ferroelectric properties are discussed in relation to the potential applications for piezoelectric MEMS. © 2012 IEEE

Soft Magnetic Properties of High-Entropy Fe-Co-Ni-Cr-Al-Si Thin Films

Directory of Open Access Journals (Sweden)

Pei-Chung Lin

2016-08-01

Full Text Available Soft magnetic properties of Fe-Co-Ni-Al-Cr-Si thin films were studied. As-deposited Fe-Co-Ni-Al-Cr-Si nano-grained thin films showing no magnetic anisotropy were subjected to field-annealing at different temperatures to induce magnetic anisotropy. Optimized magnetic and electrical properties of Fe-Co-Ni-Al-Cr-Si films annealed at 200 °C are saturation magnetization 9.13 × 105 A/m, coercivity 79.6 A/m, out-of-plane uniaxial anisotropy field 1.59 × 103 A/m, and electrical resistivity 3.75 μΩ·m. Based on these excellent properties, we employed such films to fabricate magnetic thin film inductor. The performance of the high entropy alloy thin film inductors is superior to that of air core inductor.

Synthesis and characterization of NaSbS2 thin film for potential photodetector and photovoltaic application

Institute of Scientific and Technical Information of China (English)

Zhe Xia; Jiang Tang; Feng-Xin Yu; Shuai-Cheng Lu; Ding-Jiang Xue; Yi-Su He; Bo Yang; Chong Wang; Rui-Qing Ding; Jie Zhong

2017-01-01

Solution-processed semiconductors such as perovskite compounds have attracted tremendous attention to photovoltaic research due to the significantly higher energy conversion efficiencies and lower processing costs.However,concerns over stability and the toxicity on lead in CH3NH3PbI3 create the need for still easily-accessible but more stable and environmentally friendly materials.Here,we present NaSbS2 as a non-toxic,earth-abundant promising material consisting of densely packed (1/∞) [SbS2-] polymeric chains and sodium ions.The ionic nature makes it sharing the similar dissolution superiority with perovskite,providing great potential for low-cost and large-scale fabrication.Phase pure NaSbS2 thin film was successfully fabricated using spray-pyrolysis method,and its photovoltaic relevant material,optical and electrical properties were carefully studied.Finally,a prototype NaSbS2-based thinfilm solar cell has been successfully demonstrated,yielding a power conversion efficiency of 0.13％.The systematic experimental and theoretical investigations,combined with proof-of-principle device results,indicate that NaSbS2 is indeed very promising for photovoltaic application.

Constructing a large variety of Dirac-cone materials in the Bi(1-x)Sb(x) thin film system.

Science.gov (United States)

Tang, Shuang; Dresselhaus, Mildred S

2012-12-21

We theoretically predict that a large variety of Dirac-cone materials can be constructed in Bi(1-x)Sb(x) thin films and we here show how to construct single-, bi- and tri-Dirac-cone materials with various amounts of wave vector anisotropy. These different types of Dirac cones can be of special interest to electronic device design, quantum electrodynamics and other fields.

Temperature-dependent phase separation during annealing of Ge{sub 2}Sb{sub 2}Te{sub 5} thin films in vacuum

Energy Technology Data Exchange (ETDEWEB)

Zhang Zheng [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore117602 (Singapore); Pan Jisheng, E-mail: js-pan@imre.a-star.edu.sg [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore117602 (Singapore); Fang, Lina Wei-Wei; Yeo, Yee-Chia [Department of Electrical and Computer Engineering, National University of Singapore (NUS), Singapore 119260 (Singapore); Foo, Yong Lim [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore117602 (Singapore); Zhao Rong; Shi Luping [Data Storage Institute, A-STAR (Agency for Science, Technology and Research), DSI Building, 5 Engineering Drive 1, Singapore 117608 (Singapore); Tok, Eng Soon [Institute of Materials Research and Engineering, A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore117602 (Singapore); Department of Physics, National University of Singapore (NUS), Singapore 119260 (Singapore)

2012-06-01

Thermal stability of 100 nm Ge{sub 2}Sb{sub 2}Te{sub 5} thin film during annealing from room temperature to 240 Degree-Sign C inside a UHV chamber was studied in situ by X-ray photoelectron spectroscopy (XPS) and ex situ by X-ray diffraction (XRD) and atomic force microscopy (AFM). Ge species are found to diffuse preferentially to the surface when GST film is annealed from 25 Degree-Sign C to 100 Degree-Sign C. This process is accompanied by a change of phase whereby the amorphous film completely becomes face-center-cubic (FCC) phase at 100 Degree-Sign C. From 100 Degree-Sign C to 200 Degree-Sign C, both Sb and Te species are observed to diffuse more to the surface. The FCC phase is partially changed into hexagonal-close-pack (HCP) phase at 200 Degree-Sign C. At 220 Degree-Sign C, FCC phase is completely transformed into HCP phase. Loss of Sb and Te are also detected from the surface and this is attributed to desorption due to their high vapor pressures. At 240 Degree-Sign C, Sb and Te species are found to have desorbed completely from the surface, and leave behind Ge-rich 3D droplets on the surface. The separation of Ge{sub 2}Sb{sub 2}Te{sub 5} into Sb,Te-rich phase and Ge-rich phase is thus the main mechanism to account for the failure of Ge{sub 2}Sb{sub 2}Te{sub 5}-based phase change memory devices under thermal stress.

Preparation and luminescence of green-emitting ZnAl{sub 2}O{sub 4}:Mn{sup 2+} phosphor thin films

Energy Technology Data Exchange (ETDEWEB)

Huang, Ing-Bang [Department of Materials Science and Engineering, National Formosa University, Huwei, Yunlin 632, Taiwan (China); Chang, Yee-Shin [Department of Electronic Engineering, National Formosa University, Huwei, Yunlin 632, Taiwan (China); Chen, Hao-Long [Department of Electronic Engineering, Kao Yuan University, Lujhu, Kaohsiung 821, Taiwan (China); Hwang, Ching Chiang [Department of Biotechnology, Mingdao University, Chang-Hua 52345, Taiwan (China); Jian, Chen-Jhu; Chen, Yu-Shiang [Department of Materials Science and Engineering, National Formosa University, Huwei, Yunlin 632, Taiwan (China); Tsai, Mu-Tsun, E-mail: mttsai@ms23.hinet.net [Department of Materials Science and Engineering, National Formosa University, Huwei, Yunlin 632, Taiwan (China)

2014-11-03

Nanocrystalline Mn{sup 2+}-doped zinc spinel (ZnAl{sub 2}O{sub 4}:Mn{sup 2+}) green-emitting phosphor films were deposited on silicon substrate by sol–gel spin coating and subsequent heat treatment up to 1000 °C. The effects of dopant concentration and heat treatment on the optical and structural properties were investigated. The variations in sol viscosity with time, film thickness with number of layers were also examined. Thin films were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray microscopy, atomic force microscopy, and photoluminescence spectrum. Single-phase ZnAl{sub 2}O{sub 4} started to crystallize at around 600 °C, with a normal spinel structure. On annealing at 1000 °C, the films had smooth surfaces with a nanocrystalline structure. Under UV or visible light excitation, the phosphor films exhibited an intense green emission band peaking at around 512 nm, corresponding to the typical {sup 4}T{sub 1} → {sup 6}A{sub 1} transition of tetrahedral Mn{sup 2+} ions. The most intense green emission was obtained by exciting at 456 nm. The emission intensity of films was highly dependent upon the excitation wavelength, crystallinity, dopant content, and deposition conditions. The results show that the ZnAl{sub 2}O{sub 4}:Mn{sup 2+} films have good potential for use as a green phosphor for displays and/or white light-emitting diodes. - Highlights: • ZnAl2O4:Mn2 + thin film phosphors have been synthesized by a sol–gel process. • The most intense green emission was obtained by exciting at 456 nm. • Photoluminescence is highly dependent on the crystallinity and doping content. • Emission intensity can also be modulated by controlling the film thickness.

Spin wave propagation detected over 100 μm in half-metallic Heusler alloy Co2MnSi

Science.gov (United States)

Stückler, Tobias; Liu, Chuanpu; Yu, Haiming; Heimbach, Florian; Chen, Jilei; Hu, Junfeng; Tu, Sa; Alam, Md. Shah; Zhang, Jianyu; Zhang, Youguang; Farrell, Ian L.; Emeny, Chrissy; Granville, Simon; Liao, Zhi-Min; Yu, Dapeng; Zhao, Weisheng

2018-03-01

The field of magnon spintronics offers a charge current free way of information transportation by using spin waves (SWs). Compared to forward volume spin waves for example, Damon-Eshbach (DE) SWs need a relatively weak external magnetic field which is suitable for small spintronic devices. In this work we study DE SWs in Co2MnSi, a half-metallic Heusler alloy with significant potential for magnonics. Thin films have been produced by pulsed laser deposition. Integrated coplanar waveguide (CPW) antennas with different distances between emitter and detection antenna have been prepared on a Co2MnSi film. We used a vector network analyzer to measure spin wave reflection and transmission. We observe spin wave propagation up to 100 μm, a new record for half-metallic Heusler thin films.

Structural and magnetic characterization of martensitic Ni-Mn-Ga thin films deposited on Mo foil

International Nuclear Information System (INIS)

Chernenko, V.A.; Anton, R. Lopez; Kohl, M.; Barandiaran, J.M.; Ohtsuka, M.; Orue, I.; Besseghini, S.

2006-01-01

Three martensitic Ni 51.4 Mn 28.3 Ga 20.3 thin films sputter-deposited on a Mo foil were investigated with regard to their crystal and magnetic domain structures, as well as their magnetic and magnetostrain properties. The film thicknesses, d, were 0.1, 0.4 and 1.0μm. X-ray and electron diffraction patterns revealed a tetragonal modulated martensitic phase (10M) in the films. The surface topography and micromagnetic structure were studied by scanning probe microscopy. A maze magnetic domain structure featuring a large out-of-plane magnetization component was found in all films. The domain width, δ, depends on the film thickness as δ∼d. The thickness dependencies of the saturation magnetization, saturation magnetic field and magnetic anisotropy were clarified. Beam cantilever tests on the Ni-Mn-Ga/Mo composite as a function of magnetic field showed reversible strains, which are larger than ordinary magnetostriction

Synthesis of electro-active manganese oxide thin films by plasma enhanced chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Merritt, Anna R. [Energetics Research Division, Naval Air Warfare Center Weapons Division, China Lake, CA 93555 (United States); Rajagopalan, Ramakrishnan [Department of Engineering, The Pennsylvania State University, Dubois, PA 15801 (United States); Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Carter, Joshua D. [Energetics Research Division, Naval Air Warfare Center Weapons Division, China Lake, CA 93555 (United States)

2014-04-01

The good stability, cyclability and high specific capacitance of manganese oxide (MnO{sub x}) has recently promoted a growing interest in utilizing MnO{sub x} in asymmetric supercapacitor electrodes. Several literature reports have indicated that thin film geometries of MnO{sub x} provide specific capacitances that are much higher than bulk MnO{sub x} powders. Plasma enhanced chemical vapor deposition (PECVD) is a versatile technique for the production of metal oxide thin films with high purity and controllable thickness. In this work, MnO{sub x} thin films deposited by PECVD from a methylcyclopentadienyl manganese tricarbonyl precursor are presented and the effect of processing conditions on the quality of MnO{sub x} films is described. The film purity and oxidation state of the MnO{sub x} films were studied by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Preliminary electrochemical testing of MnO{sub x} films deposited on carbon fiber electrodes in aqueous electrolytes indicates that the PECVD synthesized films are electrochemically active. - Highlights: • Plasma enhanced chemical vapor deposition of manganese oxide thin films. • Higher plasma power and chamber pressure increase deposition rate. • Manganese oxide thin films are electrochemically active. • Best electrochemical performance observed for pure film with low stress • Lower capacitance observed at higher scan rates despite thin film geometry.

Mechanism of manganese (mono and di) telluride thin-film formation and properties

Science.gov (United States)

Sharma, Raj Kishore; Singh, Gurmeet; Shul, Yong Gun; Kim, Hansung

2007-03-01

Mechanistic studies on the electrocrystallization of manganese telluride (MnTe) thin film are reported using aqueous acidic solution containing MnSO 4 and TeO 2. Tartaric acid was used for the inhibition of hydrated manganese oxide anodic growth at counter electrode. A detailed study on the mechanistic aspect of electrochemical growth of MnTe using cyclic voltametry is carried out. Conditions for electrochemical growth of manganese mono and di telluride thin films have been reported using cyclic voltammetric scans for Mn 2+, Te 4+ and combined Mn 2+ and Te 4+. X-ray diffraction showed the formation of polycrystalline MnTe films with cubic, hexagonal and orthorhombic mixed phases. MnTe film morphology was studied using scanning electron microscope. Susceptibility and electrical characterization supports the anti-ferromagnetic behavior of the as-deposited MnTe thin film.

Properties of CoSb{sub 3} films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Christen, H M; Mandrus, D G; Norton, D P; Boatner, L A; Sales, B C

1997-07-01

Polycrystalline CoSb{sub 3} films were grown on a variety of electrically insulating substrates by pulsed laser ablation from a stoichiometric hot-pressed target. These films are fully crystallized in the skutterudite structure, and the grains exhibit a strongly preferred alignment of the cubic [310]-axis perpendicular to the substrate surface. The film quality is studied for different single-crystal substrates and as a function of growth temperature and background gas. Hall measurements show that the films are p-type semiconducting with a room-temperature carrier density of 3 x 10{sup 20} holes/cm{sup 3}. The Hall mobility is found to be 50 to 60 cm{sup 2}/Vs, which is high for such a heavily-doped material. The Seebeck coefficient and the resistivity are measured as a function of temperature and are compared to bulk measurements.

Thermoelectric properties of bismuth antimony tellurium thin films through bilayer annealing prepared by ion beam sputtering deposition

Energy Technology Data Exchange (ETDEWEB)

Zheng, Zhuang-hao [College of Physics Science and Technology, Shenzhen University, 518060 (China); Shenzhen Key Laboratory of Sensor Technology, Shenzhen 518060 (China); Fan, Ping, E-mail: fanping308@126.com [College of Physics Science and Technology, Shenzhen University, 518060 (China); Shenzhen Key Laboratory of Sensor Technology, Shenzhen 518060 (China); Luo, Jing-ting [College of Physics Science and Technology, Shenzhen University, 518060 (China); Shenzhen Key Laboratory of Sensor Technology, Shenzhen 518060 (China); Cai, Xing-min; Liang, Guang-xing; Zhang, Dong-ping [College of Physics Science and Technology, Shenzhen University, 518060 (China); Ye, Fan [Shenzhen Key Laboratory of Sensor Technology, Shenzhen 518060 (China)

2014-07-01

Bismuth antimony tellurium is one of the most important tellurium-based materials for high-efficient thermoelectric application. In this paper, ion beam sputtering was used to deposit Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} bilayer thin films on borosilicate substrates at room-temperature. Then the bismuth antimony tellurium thin films were synthesized via post thermal treatment of the Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} bilayer thin films. The effect of annealing temperature and compositions on the thermoelectric properties of the thin films was investigated. After the thin films were annealed from 150 °C to 350 °C for 1 h in the high vacuum condition, the Seebeck coefficient changed from a negative sign to a positive sign. The X-ray diffraction results showed that the synthesized tellurium-based thermoelectric thin film exhibited various alloys phases, which contributed different thermoelectricity conductivity to the synthesized thin film. The overall Seebeck coefficient of the synthesized thin film changed from negative sign to positive sign, which was due to the change of the primary phase of the tellurium-based materials at different annealing conditions. Similarly, the thermoelectric properties of the films were also associated with the grown phase. High-quality thin film with the Seebeck coefficient of 240 μV K{sup −1} and the power factor of 2.67 × 10{sup −3} Wm{sup −1} K{sup −2} showed a single Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} phase when the Sb/Te thin film sputtering time was 40 min. - Highlights: • Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} thermoelectric thin films synthesized via bilayer annealing • The film has single Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} phase with best thermoelectric performance. • The film has high thermoelectric properties comparable with other best results.

Thin Film Microbatteries

International Nuclear Information System (INIS)

Dudney, Nancy J.

2008-01-01

aerosol spray coating, for one or more components of the battery. The active materials used for the thin film cathodes and anodes are familiar intercalation compounds, but the microstructures and often the cycling properties of the thin films may be quite distinct from those of battery electrodes formed from powders. The thin film cathodes are dense and homogeneous with no added phases such as binders or electrolytes. When deposited at ambient temperatures, the films of cathodes, such as LiCoO 2 , V 2 O 5 , LiMn 2 O4 , LiFePO 4 are amorphous or nanocrystalline. But even in this form, they often act as excellent cathodes with large specific capacities and good stability for hundreds to thousands of cycles. Annealing the cathode films at temperatures of 300 to 800 C may be used to induce crystallization and grain growth of the desired intercalation compound. Crystallizing the cathode film generally improves the Li chemical diffusivity in the electrode material, and hence the power delivered by the battery, by 1-2 orders of magnitude. The microstructure is also tailored by the deposition and heat treatment. Figure 3 shows a fracture edge of an annealed LiCoO 2 cathode film on an alumina substrate. The columnar microstructure, which is typical of a vapor deposited film, sinters at high temperatures leaving small fissures between the dense columns. Such crystalline films also may have a preferred crystallographic orientation. For LiCoO 2 films the crystallographic texture differs for films deposited by sputtering versus pulse laser ablation processes. To improve the manufacturability of the thin film batteries, it would be beneficial to eliminate or minimize the temperature or duration of the annealing step. Several efforts have lead to low temperature fabrication of thin film batteries on polyimide substrates, but the battery capacity and rate are lower than those treated at high temperatures. For the battery anode, many designs use a vapor-deposited metallic lithium film as

Electronic and magnetic structures of ferrimagnetic Mn{sub 2}Sb compound

Energy Technology Data Exchange (ETDEWEB)

Masrour, R., E-mail: rachidmasrour@hotmail.com [Laboratory of Materials, Processes, Environment and Quality, Cady Ayyed University, National School of Applied Sciences, 63 46000 Safi (Morocco); LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Hamedoun, M. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Benyoussef, A. [LMPHE (URAC 12), Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco); Hassan II Academy of Science and Technology, Rabat (Morocco); Mounkachi, O.; El moussaoui, H. [Institute of Nanomaterials and Nanotechnologies, MAScIR, Rabat (Morocco)

2015-01-15

The Self-consistent ab initio calculations, based on DFT (Density Functional Theory) approach and using FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the Mn{sub 2}Sb compound. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn{sub 1} and Mn{sub 2} atoms. Magnetic moment considered to lie along (0 0 1) axes are computed. The antiferromagnetic energy of Mn{sub 2}Sb systems is obtained. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The exchange interactions between the magnetic atoms Mn{sub 1}−Mn{sub 2} in Mn{sub 2}Sb are given by using the mean field theory. The HTSEs of the magnetic susceptibility of with the magnetic moments in Mn{sub 2}Sb (m{sub Mn{sub 1}}and m{sub Mn{sub 2}}) through Ising model is given up to tenth order series in (x=J(Mn{sub 1}−Mn{sub 2})/k{sub B}T). The Néel temperature T{sub N}(K) is obtained by HTSEs applied to the magnetic susceptibility series combined with the Padé approximant method. The critical exponent γ associated with the magnetic susceptibility is deduced as well. - Highlights: • Ab initio calculations is using to investigate both electronic and magnetic properties of the Mn{sub 2}Sb compound. • Obtained data from ab initio calculations are used as input for the HTSEs. • The Néel temperature is obtained for Mn{sub 2}Sb compound.

Deposition of antimony telluride thin film by ECALE

Institute of Scientific and Technical Information of China (English)

GAO; Xianhui; YANG; Junyou; ZHU; Wen; HOU; Jie; BAO; Siqian; FAN; Xi'an; DUAN; Xingkai

2006-01-01

The process of Sb2Te3 thin film growth on the Pt substrate by electrochemical atomic layer epitaxy (ECALE) was studied. Cyclic voltammetric scanning was performed to analyze the electrochemical behavior of Te and Sb on the Pt substrate. Sb2Te3 film was formed using an automated flow deposition system by alternately depositing Te and Sb atomic layers for 400 circles. The deposited Sb2Te3 films were characterized by XRD, EDX, FTIR and FESEM observation. Sb2Te3 compound structure was confirmed by XRD pattern and agreed well with the results of EDX quantitative analysis and coulometric analysis. FESEM micrographs showed that the deposit was composed of fine nano particles with size of about 20 nm. FESEM image of the cross section showed that the deposited films were very smooth and dense with thickness of about 190 nm. The optical band gap of the deposited Sb2Te3 film was determined as 0.42 eV by FTIR spectroscopy, and it was blue shifted in comparison with that of the bulk Sb2Te3 single crystal due to its nanocrystalline microstructure.

Resistance switching in epitaxial SrCoOx thin films

Science.gov (United States)

Tambunan, Octolia T.; Parwanta, Kadek J.; Acharya, Susant K.; Lee, Bo Wha; Jung, Chang Uk; Kim, Yeon Soo; Park, Bae Ho; Jeong, Huiseong; Park, Ji-Yong; Cho, Myung Rae; Park, Yun Daniel; Choi, Woo Seok; Kim, Dong-Wook; Jin, Hyunwoo; Lee, Suyoun; Song, Seul Ji; Kang, Sung-Jin; Kim, Miyoung; Hwang, Cheol Seong

2014-08-01

We observed bipolar switching behavior from an epitaxial strontium cobaltite film grown on a SrTiO3 (001) substrate. The crystal structure of strontium cobaltite has been known to undergo topotactic phase transformation between two distinct phases: insulating brownmillerite (SrCoO2.5) and conducting perovskite (SrCoO3-δ) depending on the oxygen content. The current-voltage characteristics of the strontium cobaltite film showed that it could have a reversible insulator-to-metal transition triggered by electrical bias voltage. We propose that the resistance switching in the SrCoOx thin film could be related to the topotactic phase transformation and the peculiar structure of SrCoO2.5.

Resistance switching in epitaxial SrCoOx thin films

International Nuclear Information System (INIS)

Tambunan, Octolia T.; Parwanta, Kadek J.; Acharya, Susant K.; Lee, Bo Wha; Jung, Chang Uk; Kim, Yeon Soo; Park, Bae Ho; Jeong, Huiseong; Park, Ji-Yong; Cho, Myung Rae; Park, Yun Daniel; Choi, Woo Seok; Kim, Dong-Wook; Jin, Hyunwoo; Lee, Suyoun; Song, Seul Ji; Kang, Sung-Jin; Kim, Miyoung; Hwang, Cheol Seong

2014-01-01

We observed bipolar switching behavior from an epitaxial strontium cobaltite film grown on a SrTiO 3 (001) substrate. The crystal structure of strontium cobaltite has been known to undergo topotactic phase transformation between two distinct phases: insulating brownmillerite (SrCoO 2.5 ) and conducting perovskite (SrCoO 3−δ ) depending on the oxygen content. The current–voltage characteristics of the strontium cobaltite film showed that it could have a reversible insulator-to-metal transition triggered by electrical bias voltage. We propose that the resistance switching in the SrCoO x thin film could be related to the topotactic phase transformation and the peculiar structure of SrCoO 2.5

Structural characterization of half-metallic Heusler compound NiMnSb

Energy Technology Data Exchange (ETDEWEB)

Nowicki, L. E-mail: lech.nowicki@fuw.edu.pl; Abdul-Kader, A.M.; Bach, P.; Schmidt, G.; Molenkamp, L.W.; Turos, A.; Karczewski, G

2004-06-01

High resolution X-ray diffraction (HRXRD) and Rutherford backscattering/channeling (RBS/c) techniques were used to characterize layers of NiMnSb grown by molecular beam epitaxy (MBE) on InP with a In{sub x}Ga{sub 1-x}As buffer. Angular scans in the channeling mode reveal that the crystal structure of NiMnSb is tetragonally deformed with c/a=1.010{+-}0.002, in agreement with HRXRD data. Although HRXRD demonstrates the good quality of the pseudomorphic NiMnSb layers the channeling studies show that about 20% of atoms in the layers do not occupy lattice sites in the [0 0 1] rows of NiMnSb. The possible mechanisms responsible for the observed disorder are discussed.

Structural and magnetic properties of La0.7Sr0.3MnO3 ferromagnetic thin film grown on PMN-PT by sol–gel method

Directory of Open Access Journals (Sweden)

Jing Zhang

2017-08-01

Full Text Available We report the preparation of epitaxial La0.7Sr0.3MnO3 thin films grown on (001-oriented 0.72Pb(Mg1∕3Nb2∕3O3-0.28PbTiO3 substrates by the sol–gel technique. The phase structure, magnetic properties and magnetoresistance of the samples are investigated by using high solution X-ray diffraction, atomic force microscopy, physical property measurement system, respectively. The La0.7Sr0.3MnO3 thin films display a well-defined hysteresis loop and typical ferromagnetism behavior at lower temperature. High magnetoresistance at 5T of 42% appears at 227K for La0.7Sr0.3MnO3 thin film.

Co+ -ion implantation induced doping of nanocrystalline CdS thin films: structural, optical, and vibrational properties