Stability of nanocrystalline electrochemically deposited layers

DEFF Research Database (Denmark)

Pantleon, Karen; Somers, Marcel A. J.

2009-01-01

have different microstructure and properties compared to bulk materials and the thermodynamic non-equilibrium state of as-deposited layers frequently results in changes of the microstructure as a function of time and/or temperature. The evolving microstructure affects the functionality and reliability......The technological demand for manufacturing components with complex geometries of micrometer or sub-micrometer dimensions and ambitions for ongoing miniaturization have attracted particular attention to electrochemical deposition methods. Thin layers of electrochemically deposited metals and alloys...... of electrodeposited components, which can be beneficial, as for the electrical conductivity of copper interconnect lines, or detrimental, as for reduced strength of nickel in MEMS applications. The present work reports on in-situ studies of the microstructure stability of as-deposited nanocrystalline Cu-, Ag- and Ni...

Chemical vapor deposition of nanocrystalline diamond films

International Nuclear Information System (INIS)

Vyrovets, I.I.; Gritsyna, V.I.; Dudnik, S.F.; Opalev, O.A.; Reshetnyak, O.M.; Strel'nitskij, V.E.

2008-01-01

The brief review of the literature is devoted to synthesis of nanocrystalline diamond films. It is shown that the CVD method is an effective way for deposition of such nanostructures. The basic technological methods that allow limit the size of growing diamond crystallites in the film are studied.

Porous nanostructured ZnO films deposited by picosecond laser ablation

International Nuclear Information System (INIS)

Sima, Cornelia; Grigoriu, Constantin; Besleaga, Cristina; Mitran, Tudor; Ion, Lucian; Antohe, Stefan

2012-01-01

Highlights: ► We deposite porous nanostructured ZnO films by picoseconds laser ablation (PLA). ► We examine changes of the films structure on the experimental parameter deposition. ► We demonstrate PLA capability to produce ZnO nanostructured films free of particulates. - Abstract: Porous nanostructured polycrystalline ZnO films, free of large particulates, were deposited by picosecond laser ablation. Using a Zn target, zinc oxide films were deposited on indium tin oxide (ITO) substrates using a picosecond Nd:YVO 4 laser (8 ps, 50 kHz, 532 nm, 0.17 J/cm 2 ) in an oxygen atmosphere at room temperature (RT). The morpho-structural characteristics of ZnO films deposited at different oxygen pressures (150–900 mTorr) and gas flow rates (0.25 and 10 sccm) were studied. The post-deposition influence of annealing (250–550 °C) in oxygen on the film characteristics was also investigated. At RT, a mixture of Zn and ZnO formed. At substrate temperatures above 350 °C, the films were completely oxidized, containing a ZnO wurtzite phase with crystallite sizes of 12.2–40.1 nm. At pressures of up to 450 mTorr, the porous films consisted of well-distinguished primary nanoparticles with average sizes of 45–58 nm, while at higher pressures, larger clusters (3.1–14.7 μm) were dominant, leading to thicker films; higher flow rates favored clustering.

Carbon doped ZnO: Synthesis, characterization and interpretation

International Nuclear Information System (INIS)

Mishra, D.K.; Mohapatra, J.; Sharma, M.K.; Chattarjee, R.; Singh, S.K.; Varma, Shikha; Behera, S.N.; Nayak, Sanjeev K.; Entel, P.

2013-01-01

A novel thermal plasma in-flight technique has been adopted to synthesize nanocrystalline ZnO and carbon doped nanocrystalline ZnO matrix. Transmission electron microscopy (TEM) studies on these samples show the average particle sizes to be around 32 nm for ZnO and for carbon doped ZnO. An enhancement of saturation magnetization in nanosized carbon doped ZnO matrix by a factor of 3.8 has been found in comparison to ZnO nanoparticles at room temperature. Raman measurement clearly indicates the presence of Zn–C complexes surrounded by ZnO matrix in carbon doped ZnO. This indicates that the ferromagnetic signature in carbon doped ZnO arises from the creation of defects or the development of oxy-carbon clusters, in the carbon doped ZnO system. Theoretical studies based on density functional theory also support the experimental analyses. - Highlights: ► Synthesis of nanocrystalline ZnO and carbon doped ZnO matrix by inflight thermal plasma reactor. ► Enhancement of ferromagnetism in nanosized carbon doped ZnO in comparison to ZnO nanoparticles. ► Raman measurement indicates the presence of Zn–C complexes surrounded by ZnO matrix. ► Ferromagnetic signature in carbon doped ZnO arises from the development of oxy-carbon clusters. ► DFT supports experimental evidence of ferromagnetism in C doped ZnO nanoparticles.

Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

OpenAIRE

Meilkhova, O.; Čížek, J.; Lukáč,, F.; Vlček, M.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

2013-01-01

ZnO films with thickness of ~80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects...

Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

International Nuclear Information System (INIS)

Melikhova, O.; Čížek, J.; Lukáč, F.; Vlček, M.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

2013-01-01

Highlights: ► Thin ZnO films and high quality ZnO crystal were electrochemically doped with hydrogen. ► Hydrogen absorbed in ZnO causes plastic deformation both in ZnO crystal and thin films. ► In ZnO crystal a sub-surface region with very high density of defects was formed. ► Moreover, plastic deformation causes specific surface modification of ZnO crystal. ► In ZnO films hydrogen-induced plastic deformation introduced defects in the whole film. -- Abstract: ZnO films with thickness of ∼80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects than the film deposited on amorphous FS substrate most probably due to a dense network of misfit dislocations. The ZnO films and the reference ZnO crystal were subsequently loaded with hydrogen by electrochemical cathodic charging. SPIS characterizations revealed that absorbed hydrogen introduces new defects into ZnO

Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Melikhova, O., E-mail: oksivmel@yahoo.com [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Praha 8 (Czech Republic); Čížek, J.; Lukáč, F.; Vlček, M. [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Praha 8 (Czech Republic); Novotný, M.; Bulíř, J.; Lančok, J. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Anwand, W.; Brauer, G. [Institut für Strahlenphysik, Helmholtz-Zentrum Dresden-Rossendorf, PO Box 510 119, D-01314 Dresden (Germany); Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P. [National Centre for Plasma Science and Technology, School of Physical Sciences, Glasnevin, Dublin 9 (Ireland)

2013-12-15

Highlights: ► Thin ZnO films and high quality ZnO crystal were electrochemically doped with hydrogen. ► Hydrogen absorbed in ZnO causes plastic deformation both in ZnO crystal and thin films. ► In ZnO crystal a sub-surface region with very high density of defects was formed. ► Moreover, plastic deformation causes specific surface modification of ZnO crystal. ► In ZnO films hydrogen-induced plastic deformation introduced defects in the whole film. -- Abstract: ZnO films with thickness of ∼80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects than the film deposited on amorphous FS substrate most probably due to a dense network of misfit dislocations. The ZnO films and the reference ZnO crystal were subsequently loaded with hydrogen by electrochemical cathodic charging. SPIS characterizations revealed that absorbed hydrogen introduces new defects into ZnO.

Magnetic study of nanocrystalline 0.95MnO/0.05ZnO

International Nuclear Information System (INIS)

Guskos, N.; Dudek, M.; Zolnierkiewicz, G.; Typek, J.; Berczynski, P.; Lendzion-Bielun, Z.; Sibera, D.; Narkiewicz, U.

2013-01-01

Nanocrystalline 0.95MnO/0.05ZnO sample has been prepared by coprecipitation and calcination processes. X-ray diffraction showed the presence of Mn 3 O 4 nanocrystallites with an average size of 43 nm. Magnetic properties of the 0.95MnO/0.05ZnO sample have been investigated by dc magnetization and magnetic resonances (electron paramagnetic resonance (EPR), ferromagnetic resonance (FMR)) methods. The magnetization study has shown the presence of dominating Mn 3 O 4 paramagnetic and ferrimagnetic (below 46 K) phases. The blocking temperature determined from magnetization measurements was 41 K. An FMR study has shown the evidence of the spread of nanoparticles sizes. An EPR signal from paramagnetic phase of Mn 3 O 4 was observed at temperatures above 45 K and from defects/spurious phases in the low temperature range (T<16 K). Magnetic anisotropies of the sample in the FMR spectra were taken into account by fitting the observed spectra by two lines corresponding to parallel and perpendicular orientations of nanoparticles in an applied magnetic field. - Highlights: ► Magnetic properties of 0.95MnO/0.05ZnO have been studied by dc magnetization and magnetic resonance. ► FMR and EPR spectra were identified and attributed to various spin systems. ► From the spread of blocking temperatures obtained from magnetic resonance the spread of nanoparticles sizes was estimated.

Enhancement of gas sensor response of nanocrystalline zinc oxide for ammonia by plasma treatment

International Nuclear Information System (INIS)

Hou, Yue; Jayatissa, Ahalapitiya H.

2014-01-01

The effect of oxygen plasma treatment on nanocrystalline ZnO thin film based gas sensor was investigated. ZnO thin films were synthesized on alkali-free glass substrates by a sol–gel process. ZnO thin films were treated with oxygen plasma to change the number of vacancies/defects in ZnO. The effect of oxygen plasma on the structural, electrical, optical and gas sensing properties was investigated as a function of plasma treatment time. The results suggest that the microstructure and the surface morphology can be tuned by oxygen plasma treatment. The optical transmission in the visible range varies after the oxygen plasma treatment. Moreover, it is found that the oxygen plasma has significant impact on the electrical properties of ZnO thin films indicating a variation of resistivity. The oxygen plasma treated ZnO thin film exhibits an enhanced sensing response towards NH 3 in comparison with that of the as-deposited ZnO sensor. When compared with the as-deposited ZnO film, the sensing response was improved by 50% for the optimum oxygen plasma treatment time of 8 min. The selectivity of 8 min plasma treated ZnO sensor was also examined for an important industrial gas mixture of H 2 , CH 4 and NH 3 .

Characterisation of nanocrystalline CdS thin films deposited by CBD

International Nuclear Information System (INIS)

Devi, R.; Sarma, B.K.

2006-01-01

Nanocrystalline thin films of CdS are deposited on glass substrates by chemical bath deposition using polyvinyl alcohol (PVA) matrix solution. Crystallite sizes of the films are determined from X-ray diffraction and are found to vary from 5.4 nm to 7 nm. The band gaps of the nanocrystalline material is determined from the U-V spectrograph and are found to be within the range from 2.6 eV to 2.8 eV as grain size decreases. The band gaps are also determined from the dependence of electrical conductivity of the films with temperature. An increase of molarity decreases the grain size which in turn increases the band gap. (author)

Photoluminescence of spray pyrolysis deposited ZnO nanorods

Directory of Open Access Journals (Sweden)

Mikli Valdek

2011-01-01

Full Text Available Abstract Photoluminescence of highly structured ZnO layers comprising well-shaped hexagonal rods is presented. The ZnO rods (length 500-1,000 nm, diameter 100-300 nm were grown in air onto a preheated soda-lime glass (SGL or ITO/SGL substrate by low-cost chemical spray pyrolysis method using zinc chloride precursor solutions and growth temperatures in the range of 450-550°C. We report the effect of the variation in deposition parameters (substrate type, growth temperature, spray rate, solvent type on the photoluminescence properties of the spray-deposited ZnO nanorods. A dominant near band edge (NBE emission is observed at 300 K and at 10 K. High-resolution photoluminescence measurements at 10 K reveal fine structure of the NBE band with the dominant peaks related to the bound exciton transitions. It is found that all studied technological parameters affect the excitonic photoluminescence in ZnO nanorods. PACS: 78.55.Et, 81.15.Rs, 61.46.Km

Doped nanocrystalline ZnO powders for non-linear resistor applications by spray pyrolysis method.

Science.gov (United States)

Hembram, Kaliyan; Vijay, R; Rao, Y S; Rao, T N

2009-07-01

Homogeneous and doped nanocrystalline ZnO powders (30-200 nm) were synthesized by spray pyrolysis technique. The spray pyrolysed powders were calcined in the temperature range of 500-750 degrees C. Formation of insulating pyrochlore phase started from 700 degrees C during the calcination itself. The calcined powders were compacted and sintered at different temperatures ranging from 900-1200 degrees C for 0.5-4 h. The densification behavior was found to be dependent on calcination temperature of the nanopowder. The resulting discs were found to have density (5.34-5.62 g/cc) in the range of 96-99% of theoretical density. The breakdown voltage value obtained for the nanopowder based non-linear resistor is 10.3 kV/cm with low leakage current density of 0.7 microA/cm2 and coefficient of nonlinearity as high as 193. The activation energy for grain growth of the doped ZnO nanopowder powders is 449.4 +/- 15 kJ/mol.

A comparative study of physico-chemical properties of CBD and SILAR grown ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Jambure, S.B.; Patil, S.J.; Deshpande, A.R.; Lokhande, C.D., E-mail: l_chandrakant@yahoo.com

2014-01-01

Graphical abstract: Schematic model indicating ZnO nanorods by CBD (Z{sub 1}) and nanograins by SILAR (Z{sub 2}). - Highlights: • Simple methods for the synthesis of ZnO thin films. • Comparative study of physico-chemical properties of ZnO thin films prepared by CBD and SILAR methods. • CBD outperforms SILAR method. - Abstract: In the present work, nanocrystalline zinc oxide (ZnO) thin films have been successfully deposited onto glass substrates by simple and economical chemical bath deposition (CBD) and successive ionic layer adsorption reaction (SILAR) methods. These films were further characterized for their structural, optical, surface morphological and wettability properties. The X-ray diffraction (XRD) patterns for both CBD and SILAR deposited ZnO thin films reveal the highly crystalline hexagonal wurtzite structure. From optical studies, band gaps obtained are 2.9 and 3.0 eV for CBD and SILAR deposited thin films, respectively. The scanning electron microscope (SEM) patterns show growth of well defined randomly oriented nanorods and nanograins on the CBD and SILAR deposited samples, respectively. The resistivity of CBD deposited films (10{sup 2} Ω cm) is lower than that of SILAR deposited films (10{sup 5} Ω cm). Surface wettability studies show hydrophobic nature for both films. From the above results it can be concluded that CBD grown ZnO thin films show better properties as compared to SILAR method.

A comparative study of physico-chemical properties of CBD and SILAR grown ZnO thin films

International Nuclear Information System (INIS)

Jambure, S.B.; Patil, S.J.; Deshpande, A.R.; Lokhande, C.D.

2014-01-01

Graphical abstract: Schematic model indicating ZnO nanorods by CBD (Z 1 ) and nanograins by SILAR (Z 2 ). - Highlights: • Simple methods for the synthesis of ZnO thin films. • Comparative study of physico-chemical properties of ZnO thin films prepared by CBD and SILAR methods. • CBD outperforms SILAR method. - Abstract: In the present work, nanocrystalline zinc oxide (ZnO) thin films have been successfully deposited onto glass substrates by simple and economical chemical bath deposition (CBD) and successive ionic layer adsorption reaction (SILAR) methods. These films were further characterized for their structural, optical, surface morphological and wettability properties. The X-ray diffraction (XRD) patterns for both CBD and SILAR deposited ZnO thin films reveal the highly crystalline hexagonal wurtzite structure. From optical studies, band gaps obtained are 2.9 and 3.0 eV for CBD and SILAR deposited thin films, respectively. The scanning electron microscope (SEM) patterns show growth of well defined randomly oriented nanorods and nanograins on the CBD and SILAR deposited samples, respectively. The resistivity of CBD deposited films (10 2 Ω cm) is lower than that of SILAR deposited films (10 5 Ω cm). Surface wettability studies show hydrophobic nature for both films. From the above results it can be concluded that CBD grown ZnO thin films show better properties as compared to SILAR method

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.

Growth of ZnO nanocrystals in silica by rf co-sputter deposition and post-annealing

International Nuclear Information System (INIS)

Siva Kumar, V.V.; Singh, F.; Kumar, Amit; Avasthi, D.K.

2006-01-01

Thin films with ZnO nanocrystals in silica were synthesized by rf reactive magnetron co-sputter deposition and post-annealing. The films were deposited from a ZnO/Si composite target in an rf oxygen plasma. The deposited films were annealed in air/vacuum at high temperatures to grow ZnO nanocrystals. The deposited and annealed films were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), uv-vis spectroscopy (UV-VIS) and photoluminescence (PL) measurements. FT-IR results of the films show the vibrational features of Si-O-Si and Zn-O bonds. UV-VIS spectra of the deposited film shows the band edge of ZnO. The XRD results of the films annealed at 750 deg. C and 1000 deg. C indicate the growth of ZnO nanocrystals with average crystallite sizes between 7 nm and 26 nm. PL measurements of the deposited film show a broad visible luminescence peak which can be due to ZnO. These results suggest the growth of ZnO nanocrystals in silica matrix

Atomic layer deposition of Al-doped ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

2013-01-15

Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al{sub 2}O{sub 3} on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al{sub 2}O{sub 3} phase and no further carrier doping of ZnO is observed.

Resistivity of atomic layer deposition grown ZnO: The influence of deposition temperature and post-annealing

Energy Technology Data Exchange (ETDEWEB)

Laube, J., E-mail: laube@imtek.de; Nübling, D.; Beh, H.; Gutsch, S.; Hiller, D.; Zacharias, M.

2016-03-31

Conductive zinc oxide (ZnO) films deposited by atomic layer deposition were studied as function of post-annealing treatments. Effusion experiments were conducted on ZnO films deposited at different temperatures. The influence of different annealing atmospheres on the resistivity of the films was investigated and compared to reference samples. It was found that the influence of the deposition temperature on the resistivity is much higher than that of subsequent annealings. This leads to the conclusion that reduction of the resistivity by diffusion of different gases, such as oxygen and hydrogen, into annealed ZnO films is unlikely. - Highlights: • Conformal growth of ZnO-ALD over a temperature range of 25 °C up to 300 °C. • Post-annealing in different atmospheres (H{sub 2}, O{sub 2}, vacuum) and temperatures. • Analysis of film-conductivity and effusion characteristic.

Effect of annealing on electrical properties of plasmatron deposited ZnO films

International Nuclear Information System (INIS)

Joa, Sang Beom; Penkov, Oteksiy V.; Plaksin, Vadim Yu; Mansur, Rakib; Kim, Ji Hun; Lee, Heon Ju

2009-01-01

Transparent conductive zinc oxide (ZnO) has been extensively studied in recent several years because they have very interesting properties. Besides this, zinc oxide is non-poisonous, abundant and cheap material. ZnO films are employed in different applications like transparent conductive layers in solar cells, protective coatings and so on. Wide industrial application of the ZnO films requires of development of cheap, effective and scalable technology. Typically used technology like RF sputtering, pyrolysis and metal-organic CVD don't completely satisfy the industrial requirements. In our previous publications the new perspective ZnO deposition technology based DC Arc Plasmatron was described. This technology has several advantages (low cost, high deposition rate, low substrate temperature). Currently, films deposited using this technology has can be used only as protective or insulation coatings because of very high resistance. Applying of plasmatron technology in the microelectronics or solar cell production requires the improvement of electrical properties of the films. This can be achieved by optimization of deposition parameters, using of doping, or by post-deposition treatment such as annealing, or by combination of mentioned. It was shown that proposed technology can be used for the deposition of pure ZnO film with good electrical and optical properties. Proposed technology has several disadvantages which can be overcome in the near-term outlook

Enhancement of photo sensor properties of nanocrystalline ZnO thin film by swift heavy ion irradiation

Energy Technology Data Exchange (ETDEWEB)

Mahajan, S. V.; Upadhye, D. S.; Bagul, S. B. [Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-431004 (India); Shaikh, S. U.; Birajadar, R. B.; Siddiqui, F. Y.; Huse, N. P. [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-431004 (India); Sharma, R. B., E-mail: ramphalsharma@yahoo.com, E-mail: rps.phy@gmail.com [Thin film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-431004 (India); Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-431004 (India)

2015-06-24

Nanocrystalline Zinc Oxide (ZnO) thin film prepared by Low cost Successive Ionic Layer Adsorption and Reaction (SILAR) method. This film was irradiated by 120 MeV Ni{sup 7+} ions with the fluence of 5x10{sup 12}ions/cm{sup 2}. The X-ray diffraction study was shows polycrystalline nature with wurtzite structure. The optical properties as absorbance were determined using UV-Spectrophotometer and band gap was also calculated. The Photo Sensor nature was calculated by I-V characteristics with different sources of light 40W, 60W and 100W.

ZnO: Hydroquinone superlattice structures fabricated by atomic/molecular layer deposition

International Nuclear Information System (INIS)

Tynell, Tommi; Karppinen, Maarit

2014-01-01

Here we employ atomic layer deposition in combination with molecular layer deposition to deposit crystalline thin films of ZnO interspersed with single layers of hydroquinone in an effort to create hybrid inorganic–organic superlattice structures. The ratio of the ZnO and hydroquinone deposition cycles is varied between 199:1 and 1:1, and the structure of the resultant thin films is verified with X-ray diffraction and reflectivity techniques. Clear evidence of the formation of a superlattice-type structure is observed in the X-ray reflectivity patterns and the presence of organic bonds in the films corresponding to the structure of hydroquinone is confirmed with Fourier transform infrared spectroscopy measurements. We anticipate that hybrid superlattice structures such as the ones described in this work have the potential to be of great importance for future applications where the precise control of different inorganic and organic layers in hybrid superlattice materials is required. - Highlights: • Inorganic–organic superlattices can be made by atomic/molecular layer deposition. • This is demonstrated here for ZnO and hydroquinone (HQ). • The ratio of the ZnO and HQ layers is varied between 199:1 and 14:1. • The resultant thin films are crystalline

ZnO: Hydroquinone superlattice structures fabricated by atomic/molecular layer deposition

Energy Technology Data Exchange (ETDEWEB)

Tynell, Tommi; Karppinen, Maarit, E-mail: maarit.karppinen@aalto.fi

2014-01-31

Here we employ atomic layer deposition in combination with molecular layer deposition to deposit crystalline thin films of ZnO interspersed with single layers of hydroquinone in an effort to create hybrid inorganic–organic superlattice structures. The ratio of the ZnO and hydroquinone deposition cycles is varied between 199:1 and 1:1, and the structure of the resultant thin films is verified with X-ray diffraction and reflectivity techniques. Clear evidence of the formation of a superlattice-type structure is observed in the X-ray reflectivity patterns and the presence of organic bonds in the films corresponding to the structure of hydroquinone is confirmed with Fourier transform infrared spectroscopy measurements. We anticipate that hybrid superlattice structures such as the ones described in this work have the potential to be of great importance for future applications where the precise control of different inorganic and organic layers in hybrid superlattice materials is required. - Highlights: • Inorganic–organic superlattices can be made by atomic/molecular layer deposition. • This is demonstrated here for ZnO and hydroquinone (HQ). • The ratio of the ZnO and HQ layers is varied between 199:1 and 14:1. • The resultant thin films are crystalline.

Characterization of nanocrystalline ZnO:Al films by sol-gel spin coating method

Energy Technology Data Exchange (ETDEWEB)

Gareso, P. L., E-mail: pgareso@gmail.com; Rauf, N., E-mail: pgareso@gmail.com; Juarlin, E., E-mail: pgareso@gmail.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Hasanuddin University, Makassar 90245 (Indonesia); Sugianto,; Maddu, A. [Department of Physics, Faculty of Mathematics and Natural Sciences, Bogor Institute of Culture, IPB Bogor (Indonesia)

2014-09-25

Nanocrystalline ZnO films doped with aluminium by sol-gel spin coating method have been investigated using optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. ZnO films were prepared using zinc acetate dehydrate (Zn(CH{sub 3}COO){sub 2}@@‡2H{sub 2}O), ethanol, and diethanolamine (DEA) as a starting material, solvent, and stabilizer, respectively. For doped films, AlCl{sub 3} was added to the mixture. The ZnO:Al films were deposited on a transparent conductive oxide (TCO) substrate using spin coating technique at room temperature with a rate of 3000 rpm in 30 sec. The deposited films were annealed at various temperatures from 400°C to 600°C during 60 minutes. The transmittance UV-Vis measurement results showed that after annealing at 400°C, the energy band gap profile of nanocrystalline ZnO:Al film was a blue shift. This indicated that the band gap of ZnO:Al increased after annealing due to the increase of crystalline size. As the annealing temperature increased the bandgap energy was a constant. In addition to this, there was a small oscillation occurring after annealing compared to the as–grown samples. In the case of X-RD measurements, the crystalinity of the films were amorphous before annealing, and after annealing the crystalinity became enhance. Also, X-RD results showed that structure of nanocrystalline ZnO:Al films were hexagonal polycrystalline with lattice parameters are a = 3.290 Å and c = 5.2531 Å.

Photoinduced Effects in the ZnO Luminescence Spectra

Science.gov (United States)

Akopyan, I. Kh.; Labzovskaya, M. E.; Novikov, B. V.; Lisachenko, A. A.; Serov, A. Yu.; Filosofov, N. G.

2018-02-01

The effect of intense UV irradiation on the photoluminescence (PL) spectra of ZnO powders and nanocrystalline films obtained by atomic layer deposition (ALD) was investigated. At room temperature, the behavior of the spectra under continuous UV irradiation in multiple vacuum-atmosphere cycles was studied. The changes in the intensities of exciton radiation and radiation in the "green" band region, associated with the phenomena of oxygen photodesorption and photoadsorption, are discussed. In the temperature range of 5-300 K, the effect of strong UV irradiation on the near-edge luminescence spectrum of ZnO films was studied. The nature of a new line arising in the photoluminescence spectra of an irradiated film in the region of emission of bound excitons is discussed.

Performance of inverted polymer solar cells with randomly oriented ZnO nanorods coupled with atomic layer deposited ZnO

Energy Technology Data Exchange (ETDEWEB)

Zafar, Muhammad [School of Chemical Engineering, Chonnam National University, 300 Youngbong-dong, Gwangju 500-757 (Korea, Republic of); Yun, Ju-Young [Center for Vacuum, Korea Research Institute of Standards and Science, 267 Gajeong-ro, Daejeon 305-600 (Korea, Republic of); Kim, Do-Heyoung, E-mail: kdhh@chonnam.ac.kr [School of Chemical Engineering, Chonnam National University, 300 Youngbong-dong, Gwangju 500-757 (Korea, Republic of)

2017-03-15

Highlights: • Hydrothermally grown, randomly oriented, and low areal density ZnO nanorods have been successfully adopted as the electron transport layer in inverted organic solar cells. • The addition of atomic layer deposited ZnO on the ZnO nanorods effectively enhance the photovoltaic performances of inverted organic solar cells. • The inverted organic solar cells with 5 nm thick-ALD ZnO showed the highest power conversion efficiency of 3.08%, which is an enhancement of approximately 80% compared to the cells without the ALD ZnO layer (PCE = 1.67%). - Abstract: Nanostructuring of the electron transport layer (ETL) in organic photovoltaic cells (OPV) is of great interest because it increases the surface area of the cell and electron transport. In this work, hydrothermally grown, randomly oriented, and low areal density ZnO nanorods (NRs) have been adopted as the ETL, and the effect of adding atomic layer deposited (ALD) ZnO on the ZnO NRs on the inverted organic solar cell performance has been investigated. The fabricated inverted organic solar cell with 5-nm-thick ALD-ZnO grown on the ZnO NRs showed the highest power conversion efficiency (PCE) of 3.08%, which is an enhancement of 85% from that of the cell without ALD-ZnO (PCE = 1.67%). The ultrathin ALD-ZnO was found to act as a curing layer of the surface defects on the hydrothermally grown ZnO NRs, resulting in an improvement in photovoltaic performance.

Performance of inverted polymer solar cells with randomly oriented ZnO nanorods coupled with atomic layer deposited ZnO

International Nuclear Information System (INIS)

Zafar, Muhammad; Yun, Ju-Young; Kim, Do-Heyoung

2017-01-01

Highlights: • Hydrothermally grown, randomly oriented, and low areal density ZnO nanorods have been successfully adopted as the electron transport layer in inverted organic solar cells. • The addition of atomic layer deposited ZnO on the ZnO nanorods effectively enhance the photovoltaic performances of inverted organic solar cells. • The inverted organic solar cells with 5 nm thick-ALD ZnO showed the highest power conversion efficiency of 3.08%, which is an enhancement of approximately 80% compared to the cells without the ALD ZnO layer (PCE = 1.67%). - Abstract: Nanostructuring of the electron transport layer (ETL) in organic photovoltaic cells (OPV) is of great interest because it increases the surface area of the cell and electron transport. In this work, hydrothermally grown, randomly oriented, and low areal density ZnO nanorods (NRs) have been adopted as the ETL, and the effect of adding atomic layer deposited (ALD) ZnO on the ZnO NRs on the inverted organic solar cell performance has been investigated. The fabricated inverted organic solar cell with 5-nm-thick ALD-ZnO grown on the ZnO NRs showed the highest power conversion efficiency (PCE) of 3.08%, which is an enhancement of 85% from that of the cell without ALD-ZnO (PCE = 1.67%). The ultrathin ALD-ZnO was found to act as a curing layer of the surface defects on the hydrothermally grown ZnO NRs, resulting in an improvement in photovoltaic performance.

Room-temperature deposition of crystalline patterned ZnO films by confined dewetting lithography

International Nuclear Information System (INIS)

Sepulveda-Guzman, S.; Reeja-Jayan, B.; De la Rosa, E.; Ortiz-Mendez, U.; Reyes-Betanzo, C.; Cruz-Silva, R.; Jose-Yacaman, M.

2010-01-01

In this work patterned ZnO films were prepared at room-temperature by deposition of ∼5 nm size ZnO nanoparticles using confined dewetting lithography, a process which induces their assembly, by drying a drop of ZnO colloidal dispersion between a floating template and the substrate. Crystalline ZnO nanoparticles exhibit a strong visible (525 nm) light emission upon UV excitation (λ = 350 nm). The resulting films were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). The method described herein presents a simple and low cost method to prepare crystalline ZnO films with geometric patterns without additional annealing. Such transparent conducting films are attractive for applications like light emitting diodes (LEDs). As the process is carried out at room temperature, the patterned crystalline ZnO films can even be deposited on flexible substrates.

Room-temperature deposition of crystalline patterned ZnO films by confined dewetting lithography

Energy Technology Data Exchange (ETDEWEB)

Sepulveda-Guzman, S., E-mail: selene.sepulvedagz@uanl.edu.mx [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia. UANL, PIIT Monterrey, CP 66629, Apodaca NL (Mexico); Reeja-Jayan, B. [Texas Materials Institute, University of Texas at Austin, Austin, TX 78712 (United States); De la Rosa, E. [Centro de Investigacion en Optica, Loma del Bosque 115 Col. Lomas del Campestre C.P. 37150 Leon, Gto. Mexico (Mexico); Ortiz-Mendez, U. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia. UANL, PIIT Monterrey, CP 66629, Apodaca NL (Mexico); Reyes-Betanzo, C. [Instituto Nacional de Astrofisica Optica y Electronica, Calle Luis Enrique Erro No. 1, Santa Maria Tonanzintla, Puebla. Apdo. Postal 51 y 216, C.P. 72000 Puebla (Mexico); Cruz-Silva, R. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, UAEM. Av. Universidad 1001, Col. Chamilpa, CP 62210 Cuernavaca, Mor. (Mexico); Jose-Yacaman, M. [Physics and Astronomy Department University of Texas at San Antonio 1604 campus San Antonio, TX 78249 (United States)

2010-03-15

In this work patterned ZnO films were prepared at room-temperature by deposition of {approx}5 nm size ZnO nanoparticles using confined dewetting lithography, a process which induces their assembly, by drying a drop of ZnO colloidal dispersion between a floating template and the substrate. Crystalline ZnO nanoparticles exhibit a strong visible (525 nm) light emission upon UV excitation ({lambda} = 350 nm). The resulting films were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM). The method described herein presents a simple and low cost method to prepare crystalline ZnO films with geometric patterns without additional annealing. Such transparent conducting films are attractive for applications like light emitting diodes (LEDs). As the process is carried out at room temperature, the patterned crystalline ZnO films can even be deposited on flexible substrates.

Vertical resistivity in nanocrystalline ZnO and amorphous InGaZnO

Science.gov (United States)

McCandless, Jonathan P.; Leedy, Kevin D.; Schuette, Michael L.

2018-02-01

The goal is to gain additional insight into physical mechanisms and the role of microstructure on the formation of ohmic contacts and the reduction of contact resistance. We have measured a decreasing film resistivity in the vertical direction with increasing thickness of pulsed-laser deposited ZnO and IGZO. As the ZnO thickness increases from 122 nm to 441 nm, a reduction in resistivity from 3.29 Ω-cm to 0.364 Ω-cm occurred. The IGZO resistivity changes from 72.4 Ω-cm to 0.642 Ω-cm as the film is increased from 108nm to 219 nm. In the ZnO, the size of nanocolumnar grains increase with thickness resulting in fewer grain boundaries, and in the amorphous IGZO, the thicker region exhibits tunnel-like artifacts which may contribute to the reduced resistivity.

Improvement in Performance of ZnO based DSC Prepared by Spraying Method

Directory of Open Access Journals (Sweden)

Rangga Winantyo

2013-09-01

Full Text Available This paper reports the effect of TiCl4 on the performance of ZnO based DSC. ZnO was used due to its stability against photo-corrosion  and  photochemical  properties  similar  to  TiO2.  Thin  films  of  nanocrystalline  ZnO  were  deposited  on transparent conducting oxide glass using spray  method. The ZnO  films  were treated using TiCl4. The cell’s efficiency was found to be 2.5% with TiCl4 post-treatment and 1.9% without TiCl4 post-treatment.

Sims Characterisation of ZnO Layer Prepared By Pulsed Laser Deposition

Directory of Open Access Journals (Sweden)

Andrej Vincze

2005-01-01

Full Text Available New material development requires new technologies to create and prepare basic material for semiconductor industry and device applications. Materials have given properties, which exhibit particulary small tolerances. One of the most important and promising material is recently ZnO. ZnO has specific properties for near UV emission and absorption optical devices. The pulsed laser deposition (PLD is one of the methods to prepare this type of material. The aim of this paper is to compare properties of ZnO layers deposited from pure Zn target in oxygen atmosphere and the analysis of their surface properties by secondary ion mass spectroscopy (SIMS, atomic force microscopy (AFM and scanning electron microscopy (SEM.

Solution precursor plasma deposition of nanostructured ZnO coatings

International Nuclear Information System (INIS)

Tummala, Raghavender; Guduru, Ramesh K.; Mohanty, Pravansu S.

2011-01-01

Highlights: → The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. → It is highly capable of developing tailorable nanostructures. → This technique can be employed to spray the coatings on any kind of substrates including polymers. → The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance (∼65-80%) and reflectivity (∼65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 mΩ cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

Solution precursor plasma deposition of nanostructured ZnO coatings

Energy Technology Data Exchange (ETDEWEB)

Tummala, Raghavender [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Guduru, Ramesh K., E-mail: rkguduru@umich.edu [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States); Mohanty, Pravansu S. [Department of Mechanical Engineering, University of Michigan - Dearborn, MI 48128 (United States)

2011-08-15

Highlights: {yields} The solution precursor route employed is an inexpensive process with capability to produce large scale coatings at fast rates on mass scale production. {yields} It is highly capable of developing tailorable nanostructures. {yields} This technique can be employed to spray the coatings on any kind of substrates including polymers. {yields} The ZnO coatings developed via solution precursor plasma spray process have good electrical conductivity and reflectivity properties in spite of possessing large amount of particulate boundaries, porosity and nanostructured grains. -- Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material that has various applications including optical, electronic, biomedical and corrosion protection. It is usually synthesized via processing routes, such as vapor deposition techniques, sol-gel, spray pyrolysis and thermal spray of pre-synthesized ZnO powders. Cheaper and faster synthesis techniques are of technological importance due to increased demand in alternative energy applications. Here, we report synthesis of nanostructured ZnO coatings directly from a solution precursor in a single step using plasma spray technique. Nanostructured ZnO coatings were deposited from the solution precursor prepared using zinc acetate and water/isopropanol. An axial liquid atomizer was employed in a DC plasma spray torch to create fine droplets of precursor for faster thermal treatment in the plasma plume to form ZnO. Microstructures of coatings revealed ultrafine particulate agglomerates. X-ray diffraction confirmed polycrystalline nature and hexagonal Wurtzite crystal structure of the coatings. Transmission electron microscopy studies showed fine grains in the range of 10-40 nm. Observed optical transmittance ({approx}65-80%) and reflectivity ({approx}65-70%) in the visible spectrum, and electrical resistivity (48.5-50.1 m{Omega} cm) of ZnO coatings are attributed to ultrafine particulate morphology of the coatings.

Atomic layer deposition of B-doped ZnO using triisopropyl borate as the boron precursor and comparison with Al-doped ZnO

NARCIS (Netherlands)

Garcia - Alonso, D.; Potts, S.E.; Helvoirt, van C.A.A.; Verheijen, M.A.; Kessels, W.M.M.

2015-01-01

Doped ZnO films are an important class of transparent conductive oxides, with many applications demanding increased growth control and low deposition temperatures. Therefore, the preparation of B-doped ZnO films by atomic layer deposition (ALD) at 150 °C was studied. The B source was triisopropyl

Structural characterization of ZnO thin films grown on various substrates by pulsed laser deposition

International Nuclear Information System (INIS)

Novotný, M; Bulíř, J; Lančok, J; Čížek, J; Kužel, R; Connolly, J; McCarthy, E; Krishnamurthy, S; Mosnier, J-P; Anwand, W; Brauer, G

2012-01-01

ZnO thin films were grown by pulsed laser deposition on three different substrates: sapphire (0 0 0 1), MgO (1 0 0) and fused silica (FS). The structure and morphology of the films were characterized by x-ray diffraction and scanning electron microscopy and defect studies were carried out using slow positron implantation spectroscopy (SPIS). Films deposited on all substrates studied in this work exhibit the wurtzite ZnO structure and are characterized by an average crystallite size of 20-100 nm. However, strong differences in the microstructure of films deposited on various substrates were found. The ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit local epitaxy, i.e. a well-defined relation between film crystallites and the substrate. Domains with different orientation relationships with the substrate were found in both films. On the other hand, the film deposited on the FS substrate exhibits fibre texture with random lateral orientation of crystallites. Extremely high compressive in-plane stress of σ ∼ 14 GPa was determined in the film deposited on the MgO substrate, while the film deposited on sapphire is virtually stress-free, and the film deposited on the FS substrate exhibits a tensile in-plane stress of σ ∼ 0.9 GPa. SPIS investigations revealed that the concentration of open-volume defects in the ZnO films is substantially higher than that in a bulk ZnO single crystal. Moreover, the ZnO films deposited on MgO and sapphire single-crystalline substrates exhibit a significantly higher density of defects than the film deposited on the amorphous FS substrate. (paper)

Effect of different solutions on electrochemical deposition of ZnO

International Nuclear Information System (INIS)

Asil, H.; Chinar, K.; Gur, E.; Tuzemen, S.

2010-01-01

ZnO thin films were grown by electrochemical deposition (ECD) onto indium tin oxide using different compounds such as Zn(NO 3 ) 2 , Zn(C 2 H 3 O 2 ) 2 , ZnCl 2 , Zn(ClO 4 ) 2 and different solvents such as dimethylsulfoxide (DMSO) and 18 M deionized water. Furthermore, solutions were prepared using different electrolytes and concentrations in order to determine the optimum deposition parameters of ZnO. All the grown films were characterized by X-ray diffraction, optical absorption and photoluminescence measurement techniques. It is indicated that films grown by using Zn(ClO 4 ) 2 show high crystallinity and optical quality. The X-ray diffraction analysis showed that ZnO thin films which were grown electrochemically in a non-aqueous solution (DMSO) prepared by Zn(ClO 4 ) 2 have highly c-axis preferential orientation. PL measurements showed that ZnO thin films grown in Zn(ClO 4 ) 2 indicates high quality emission characteristics compared to the thin films grown by other solutions

ZnO crystal growth on microelectrode by electrochemical deposition method

International Nuclear Information System (INIS)

Kondo, Y; Ashida, A; Nouzu, N; Fujimura, N

2011-01-01

Zinc Oxide crystals were grown by constant potential electrochemical deposition method on the substrate with the Pt working electrode which consists of Pt film with large area and μm-sized line and space structured area. In case of depositions with cathodic potential of -0.3V, ZnO crystal is not observed on the micro electrode, but observed on the electrode with large area (0.2 cm 2 ). By using electrolyte with higher pH, ZnO crystal grows on both areas. In case of lower pH, ZnO crystal does not grow on either. From these results, the pH range for growth of ZnO on the microelectrode seems to be higher than that on the electrode with large area. And, it is expected that the pH just on the surface of μm-sized electrode is lower than that in the bulk of electrolyte. Based on these results, it can be concluded that control of the pH in vicinity of the surface is very important to ECD method for micro- and nano-scaled devices.

Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

Energy Technology Data Exchange (ETDEWEB)

Garcés, F.A., E-mail: felipe.garces@santafe-conicet.gov.ar [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Budini, N. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Schmidt, J.A.; Arce, R.D. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, Santa Fe S3000AOM (Argentina)

2016-04-30

Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties. - Highlights: • Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained. • Mosaicity between crystalline domains increased with film thickness. • Lattice parameters a and c diminished linearly as a function of Al concentration. • First steps for developing porous silicon/doped ZnO heterojunctions were presented.

Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

International Nuclear Information System (INIS)

Garcés, F.A.; Budini, N.; Schmidt, J.A.; Arce, R.D.

2016-01-01

Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties. - Highlights: • Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained. • Mosaicity between crystalline domains increased with film thickness. • Lattice parameters a and c diminished linearly as a function of Al concentration. • First steps for developing porous silicon/doped ZnO heterojunctions were presented.

Effect of different sol concentrations on the properties of nanocrystalline ZnO thin films grown on FTO substrates by sol-gel spin-coating

International Nuclear Information System (INIS)

Kim, Ikhyun; Kim, Younggyu; Nam, Giwoong; Kim, Dongwan; Park, Minju; Kim, Haeun; Lee, Wookbin; Leem, Jaeyoung; Kim, Jongsu; Kim, Jin Soo

2014-01-01

Nanocrystalline ZnO thin films grown on fluorine-doped tinoxide (FTO) substrates were fabricated using the spin-coating method. The structural and the optical properties of the ZnO thin films prepared using different sol concentrations were investigated by using field-emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), photoluminescence (PL) measurements, and ultraviolet-visible (UV-vis) spectrometry. The surface morphology of the ZnO thin films, as observed in the SEM images, exhibited a mountain-chain structure. XRD results indicated that the thin films were preferentially orientated along the direction of the c-axis and that the grain size of the ZnO thin films increased with increasing sol concentration. The PL spectra showed a strong ultraviolet emission peak at 3.22 eV and a broad orange emission peak at 2.0 eV. The intensities of deep-level emission (DLE) gradually increased with increasing sol concentration from 0.4 to 1.0 M. The transmittance spectra of the ZnO thin films showed that the ZnO thin films were transparent (∼85%) in the visible region and exhibited sharp absorption edges at 375 nm. Thus, The Urbach energy of ZnO thin films decreased with increasing sol concentration.

A hierarchically assembled mesoporous ZnO hemisphere array and hollow microspheres for photocatalytic membrane water filtration.

Science.gov (United States)

Pan, Jia Hong; Zhang, Xiwang; Du, Alan J; Bai, Hongwei; Ng, Jiawei; Sun, Darren

2012-05-28

A mesoporous ZnO hemisphere array has been prepared via a topotactic transition of Zn(4)(OH)(6)CO(3)·H(2)O (ZCHH) by chemical bath deposition. Each hemisphere is comprised of a radially oriented nanoflake shell grown on the hemispherical interior. Reaction time-dependent SEM analysis shows that the morphological formation of ZCHH involves a deposition-growth-secondary growth-redeposition procedure. Upon calcination, ZCHH readily decomposes to nanocrystalline wurtzite-phase ZnO without significant change in morphology, and the release of CO(2) and H(2)O from ZCHH creates an additional mesoporous structure in both hemispherical interior and nanoflake shell. A similar process but without using a substrate has been developed for synthesis of mesoporous ZnO hollow microspheres in powder form. Both the elaborated superstructured photocatalysts consisting of mesoporous nanoflakes have been demonstrated to exhibit excellent performances in the photocatalytic membrane filtration.

Superhydrophobic nanostructured ZnO thin films on aluminum alloy substrates by electrophoretic deposition process

Energy Technology Data Exchange (ETDEWEB)

Huang, Ying; Sarkar, D.K., E-mail: dsarkar@uqac.ca; Chen, X-Grant

2015-02-01

Graphical abstract: - Highlights: • Fabrication of superhydrophobic ZnO thin films surfaces by electrophoretic deposition process on aluminum substrates. • Effect of bath temperature on the physical and superhydrophobic properties of thin films. • The water contact angle of 155° ± 3 with roll off property has been observed on the film that was grown at bath temperatures of 50 °C. • The activation energy for electrophoretic deposition of SA-functionalized ZnO nanoparticle is calculated to be 0.50 eV. - Abstract: Superhydrophobic thin films have been fabricated on aluminum alloy substrates by electrophoretic deposition (EPD) process using stearic acid (SA) functionalized zinc oxide (ZnO) nanoparticles suspension in alcohols at varying bath temperatures. The deposited thin films have been characterized using both X-ray diffraction (XRD) and infrared (IR) spectroscopy and it is found that the films contain low surface energy zinc stearate and ZnO nanoparticles. It is also observed that the atomic percentage of Zn and O, roughness and water contact angle of the thin films increase with the increase of the deposited bath temperature. Furthermore, the thin film deposited at 50 °C, having a roughness of 4.54 ± 0.23 μm, shows superhydrophobic properties providing a water contact angle of 155 ± 3° with rolling off properties. Also, the activation energy of electrophoretic deposition of stearic-acid-functionalized ZnO nanoparticles is calculated to be 0.5 eV.

Chemical bath deposited PbS thin films on ZnO nanowires for photovoltaic applications

Energy Technology Data Exchange (ETDEWEB)

Gertman, Ronen [Dept of Chemistry, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Osherov, Anna; Golan, Yuval [Dept of Materials Engineering, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Visoly-Fisher, Iris, E-mail: irisvf@bgu.ac.il [Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Be' er Sheva 84105 (Israel); Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Sede Boqer Campus 84990 (Israel)

2014-01-01

Photovoltaic devices usually exploit mid-range band-gap semiconductors which absorb in the visible range of the solar spectrum. However, much energy is lost in the IR and near-IR range. We combined the advantages of small band-gap, bulk-like PbS deposited by facile, cheap and direct chemical bath deposition (CBD), with the good electronic properties of ZnO and the large surface area of nanowires, towards low cost photovoltaic devices utilizing IR and near-IR light. Surprisingly, CBD of PbS on ZnO, and particularly on ZnO nanowires, was not studied hitherto. Therefore, the mechanism of PbS growth by chemical bath deposition on ZnO nanowires was studied in details. A visible proof is shown for a growth mechanism starting from amorphous Pb(OH){sub 2} layer, that evolved into the ‘ion-by-ion’ growth mechanism. The growth mechanism and the resulting morphology at low temperatures were controlled by the thiourea concentration. The grain size affected the magnitude of the band-gap and was controlled by the deposition temperatures. Deposition above 40 °C resulted in bulk-like PbS with an optical band-gap of 0.4 eV. Methods were demonstrated for achieving complete PbS coverage of the complex ZnO NW architecture, a crucial requirement in optoelectronic devices to prevent shorts. Measurements of photocurrents under white and near-IR (784 nm) illumination showed that despite a 200 meV barrier for electron transfer at the PbS/ZnO interface, extraction of photo-electrons from PbS to the ZnO was feasible. The ability to harvest electrons from a narrow band-gap semiconductor deposited on a large surface-area electrode can advance the field towards high efficiency, low cost IR and near-IR sensors and third generation solar cells. - Highlights: • PbS was deposited on ZnO nanowires using chemical bath deposition. • At 50 °C the growth mechanism starts from an amorphous Pb(OH){sub 2} layer. • At 5 °C the growth mechanism of PbS can be controlled by thiourea concentrations

Al-doped ZnO seed layer-dependent crystallographic control of ZnO nanorods by using electrochemical deposition

Energy Technology Data Exchange (ETDEWEB)

Son, Hyo-Soo; Choi, Nak-Jung [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of); Kim, Kyoung-Bo [Department of Metallurgical and Materials Engineering, Inha Technical College, Incheon 402-752 (Korea, Republic of); Kim, Moojin [Department of Renewable Energy, Jungwon University, Goesan-gun, Chungbuk 367-805 (Korea, Republic of); Lee, Sung-Nam, E-mail: snlee@kpu.ac.kr [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of)

2016-10-15

Highlights: • Polar and semipolar ZnO NRs were successfully achieved by hydrothermal synthesis. • Semipolar and polar ZnO NRs were grown on ZnO and AZO/m-sapphire, respectively. • Al % of AZO/m-sapphire enhanced the lateral growth rate of polar ZnO NRs. - Abstract: We investigated the effect of an Al-doped ZnO film on the crystallographic direction of ZnO nanorods (NRs) using electrochemical deposition. From high-solution X-ray diffraction measurements, the crystallographic plane of ZnO NRs grown on (1 0 0) ZnO/m-plane sapphire was (1 0 1). The surface grain size of the (100) Al-doped ZnO (AZO) film decreased with increasing Al content in the ZnO seed layer, implying that the Al dopant accelerated the three-dimensional (3D) growth of the AZO film. In addition, it was found that with increasing Al doping concentration of the AZO seed layer, the crystal orientation of the ZnO NRs grown on the AZO seed layer changed from [1 0 1] to [0 0 1]. With increasing Al content of the nonpolar (1 0 0) AZO seed layer, the small surface grains with a few crystallographic planes of the AZO film changed from semipolar (1 0 1) ZnO NRs to polar (0 0 1) ZnO NRs due to the increase of the vertical [0 0 1] growth rate of the ZnO NRs owing to excellent electrical properties.

Suppression of the green photoluminescence band in ZnO embedded into porous opal by spray pyrolysis

International Nuclear Information System (INIS)

Abrarov, S.M.; Yuldashev, Sh.U.; Lee, S.B.; Kang, T.W.

2004-01-01

The photoluminescence (PL) and transmittance characteristics of the zinc oxide embedded into voids of FCC sub-micron packed silicon dioxide spheres by using technologically simple and inexpensive spray pyrolysis are reported. The uniform formation of ZnO nanocrystalline particles inside of the porous opal takes place after deposition in aqueous solution with zinc nitrite hexahydride precursor followed by thermal annealing. The decrease of green PL is observed due to the inhibition of spontaneous emission through oxygen vacancies in ZnO. The strong red shift of the transmittance characteristics signifies the essential filling of voids in the opal matrix

Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

International Nuclear Information System (INIS)

Shinde, S.S.; Shinde, P.S.; Sapkal, R.T.; Oh, Y.W.; Haranath, D.; Bhosale, C.H.; Rajpure, K.Y.

2012-01-01

Highlights: ► Influence of substrate temperature onto the physico-chemical properties. ► Photochemical, structural, luminescent, optoelectrical and thermal properties. ► The kinetics of oxalic acid degradation with reaction mechanism. ► Extent of mineralization by COD and TOC. - Abstract: The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV–Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (I sc = 0.357 mA) and open circuit voltage (V oc = 0.48 V). Direct band gap calculated by considering R and T values of ZnO thin films increases from 3.14–3.21 eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

ZnO based nanowires grown by chemical vapour deposition for selective hydrogenation of acetylene alcohols

NARCIS (Netherlands)

Protasova, L.N.; Rebrov, E.; Choy, K.L.; Pung, S.Y.; Engels, V.; Cabaj, M.; Wheatley, A.E.H.; Schouten, J.C.

2011-01-01

Vertically aligned ZnO nanowires (NWs) with a length of 1.5–10 µm and a mean diameter of ca. 150 nm were grown by chemical vapour deposition onto a c-oriented ZnO seed layer which was deposited by atomic layer deposition on Si substrates. The substrates were then spin-coated with an ethanol solution

Low-temperature processed ZnO and CdS photodetectors deposited by pulsed laser deposition

International Nuclear Information System (INIS)

Hernandez-Como, N; Moreno, S; Mejia, I; Quevedo-Lopez, M A

2014-01-01

UV-VIS photodetectors using an interdigital configuration, with zinc oxide (ZnO) and cadmium sulfide (CdS) semiconductors deposited by pulsed laser deposition, were fabricated with a maximum processing temperature of 100 °C. Without any further post-growth annealing, the photodetectors are compatible with flexible and transparent substrates. Aluminum (Al) and indium tin oxide (ITO) were investigated as contacts. Focusing on underwater communications, the impact of metal contact (ITO versus Al) was investigated to determine the maximum responsivity using a laser with a 405 nm wavelength. As expected, the responsivity increases for reduced metal finger separation. This is a consequence of reduced carrier transit time for shorter finger separation. For ITO, the highest responsivities for both films (ZnO and CdS) were ∼3 A W −1 at 5 V. On the other hand, for Al contacts, the maximum responsivities at 5 V were ∼0.1 A W −1 and 0.7 A W −1 for CdS and ZnO, respectively. (paper)

Oxidant-Dependent Thermoelectric Properties of Undoped ZnO Films by Atomic Layer Deposition

KAUST Repository

Kim, Hyunho

2017-02-27

Extraordinary oxidant-dependent changes in the thermoelectric properties of undoped ZnO thin films deposited by atomic layer deposition (ALD) have been observed. Specifically, deionized water and ozone oxidants are used in the growth of ZnO by ALD using diethylzinc as a zinc precursor. No substitutional atoms have been added to the ZnO films. By using ozone as an oxidant instead of water, a thermoelectric power factor (σS) of 5.76 × 10 W m K is obtained at 705 K for undoped ZnO films. In contrast, the maximum power factor for the water-based ZnO film is only 2.89 × 10 W m K at 746 K. Materials analysis results indicate that the oxygen vacancy levels in the water- and ozone-grown ZnO films are essentially the same, but the difference comes from Zn-related defects present in the ZnO films. The data suggest that the strong oxidant effect on thermoelectric performance can be explained by a mechanism involving point defect-induced differences in carrier concentration between these two oxides and a self-compensation effect in water-based ZnO due to the competitive formations of both oxygen and zinc vacancies. This strong oxidant effect on the thermoelectric properties of undoped ZnO films provides a pathway to improve the thermoelectric performance of this important material.

Investigation of the pulsed electrochemical deposition of ZnO

International Nuclear Information System (INIS)

Dunkel, Christian; Lüttich, Franziska; Graaf, Harald; Oekermann, Torsten; Wark, Michael

2012-01-01

The influence of pulse parameters on the morphology of ZnO prepared by pulsed cathodic electrodeposition from oxygen-saturated aqueous ZnCl 2 solution on ITO (indium tin oxide)/glass substrates was investigated. It was found that the ratio between the pulse and the pause duration has a crucial influence on the crystal growth, reaching the highest density of the films with pause/pulse-ratios between 0.25 and 1. Longer pauses cause an Ostwald-like ripening of the ZnO crystals and therewith a strong change in the crystal morphology from roundly shaped to hexagonal. Also the hydrophilicity of the substrate resulting from pre-treatment has a crucial influence on the deposited films, leading to films only consisting of few large and separately grown ZnO crystals for highly hydrophilic substrates and an increasing fraction of small densely grown ZnO crystals with increasing hydrophobicity.

Nanostructured Zn and ZnO nanowire thin films for mechanical and self-cleaning applications

Energy Technology Data Exchange (ETDEWEB)

Shaik, Ummar Pasha [Advanced Centre of Research in High Energy Materials, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); Purkayastha, Debarun Dhar, E-mail: ddebarun@yahoo.com [Department of Physics, National Institute of Technology Nagaland, Chumukedima, Dimapur 797103 (India); Krishna, M. Ghanashyam [Advanced Centre of Research in High Energy Materials, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); School of Physics, University of Hyderabad, Prof. C R Rao Road, Gachibowli, Hyderabad 500046 (India); Madhurima, V. [Department of Physics, Central University of Tamil Nadu, Thiruvarur 610004 (India)

2015-03-01

Highlights: • Zn metal films were deposited by thermal evaporation, on various substrates. • Upon annealing Zn there is transformation of the Zn nanosheets into ZnO nanowires. • ZnO nanowires are superhydrophobic and exhibit wetting transition on UV exposure. • ZnO will be useful in self-cleaning, mechanical and oxidation resistance surfaces. - Abstract: Nanostructured Zn metal films were deposited by thermal evaporation, on borosilicate glass, Quartz, sapphire, lanthanum aluminate and yttria stabilized zirconia substrates. The as-deposited films are nanocrystalline and show a morphology that consists of triangular nanosheets. The films are hydrophobic with contact angles between 102° and 120° with hardness and Young's modulus between 0.15–0.8 GPa and 18–300 GPa, respectively. Thermal annealing of the films at 500 °C results only in partial oxidation of Zn to ZnO, which indicates good oxidation resistance. Annealing also causes transformation of the Zn nanosheets into ZnO nanowires that are polycrystalline in nature. The ZnO nanowires are superhydrophobic with contact angles between 159° and 162°, contact angle hysteresis between 5° and 10° and exhibit a reversible superhydrophobic–hydrophilic transition under UV irradiation. The nanowires are much softer than the as-deposited Zn metal films, with hardness between 0.02 and 0.4 GPa and Young's modulus between 3 and 35 GPa. The current study thus demonstrates a simple process for fabrication of nanostructured Zn metal films followed by a one-step transformation to nanowires with properties that will be very attractive for mechanical and self-cleaning applications.

Pulsed-laser deposited ZnO for device applications

NARCIS (Netherlands)

King, S.L.; Gardeniers, Johannes G.E.; Boyd, I.W.

1996-01-01

The study investigates the growth by pulsed-laser deposition (PLD) of ZnO thin films for the eventual incorporation into piezo-electric actuators and other sensors being developed at the University of Twente. All films are purely c-axis oriented, and results are presented which suggest the

Growth of aligned ZnO nanowires via modified atmospheric pressure chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yuping; Li, Chengchen [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Mingming, E-mail: andychain@live.cn [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Yu, Xiao; Chang, Yunwei [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Anqi [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Zhu, Hai, E-mail: zhuhai5@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Tang, Zikang, E-mail: zktang@umac.mo [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); The Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau (China)

2016-12-09

In this work, we report the growth of high-quality aligned ZnO nanowires via a facile atmospheric pressure chemical vapor deposition (CVD) method. The CVD reactor chamber used was more complicated than a conventional one due to the quartz boats loaded with sources (ZnO/C) and substrates being inserted into a semi-open quartz tube, and then placed inside the CVD reactor. The semi-open quartz tube played a very important role in growing the ZnO nanowires, and demonstrated that the transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber. Aligned ZnO nanowires were successfully obtained, though they were only found at substrates located upstream. The very high crystalline quality of the obtained ZnO nanowires was demonstrated by high-resolution transmission electron microscopy and room temperature photoluminescence investigations. Such ZnO nanowires with high crystalline quality may provide opportunities for the fabrication of ZnO-based nano-devices in future. - Highlights: • High-quality aligned ZnO nanowires were obtained via modified chemical vapor deposition under atmospheric pressure. • The semi-open quartz tube plays very important roles in growing ZnO nanowires. • The transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber.

Growth of aligned ZnO nanowires via modified atmospheric pressure chemical vapor deposition

International Nuclear Information System (INIS)

Zhao, Yuping; Li, Chengchen; Chen, Mingming; Yu, Xiao; Chang, Yunwei; Chen, Anqi; Zhu, Hai; Tang, Zikang

2016-01-01

In this work, we report the growth of high-quality aligned ZnO nanowires via a facile atmospheric pressure chemical vapor deposition (CVD) method. The CVD reactor chamber used was more complicated than a conventional one due to the quartz boats loaded with sources (ZnO/C) and substrates being inserted into a semi-open quartz tube, and then placed inside the CVD reactor. The semi-open quartz tube played a very important role in growing the ZnO nanowires, and demonstrated that the transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber. Aligned ZnO nanowires were successfully obtained, though they were only found at substrates located upstream. The very high crystalline quality of the obtained ZnO nanowires was demonstrated by high-resolution transmission electron microscopy and room temperature photoluminescence investigations. Such ZnO nanowires with high crystalline quality may provide opportunities for the fabrication of ZnO-based nano-devices in future. - Highlights: • High-quality aligned ZnO nanowires were obtained via modified chemical vapor deposition under atmospheric pressure. • The semi-open quartz tube plays very important roles in growing ZnO nanowires. • The transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber.

Synthesis and characterization of electrochemically deposited nanocrystalline CdTe thin films

Energy Technology Data Exchange (ETDEWEB)

Singh, Ragini Raj, E-mail: raginirajsingh@gmail.com [Department of Physics, Bhopal University, Bhopal-462026 (India); Department of Physical Electronics, Iby and Aladar Fleishman Faculty of Engineering, Tel-Aviv University, Tel-Aviv-69978 (Israel); Painuly, Diksha [Centre for Nanoscience and Nanotechnology, University of Kerala, Thiruanantpuram, Kerala (India); Pandey, R.K. [Department of Physics, Bhopal University, Bhopal-462026 (India)

2009-07-15

Electrodeposition is emerging as a method for the synthesis of semiconductor thin films and nanostructures. In this work we prepared the nanocrystalline CdTe thin films on indium tin oxide coated glass substrate from aqueous acidic bath at the deposition temperature 50 {+-} 1 deg. C. The films were grown potentiostatically from -0.60 V to -0.82 V with respect to saturated calomel reference electrode. The structural, compositional, morphological and optical properties were investigated using X-ray diffraction (XRD), energy dispersive analysis by X-rays (EDAX), atomic force microscopy (AFM), and UV-vis spectroscopy respectively and cyclic voltammetery. The structural and optical studies revealed that films are nanocrystalline in nature and possess cubic phase, also the films are preferentially oriented along the cubic (1 1 1) plane. The effect of cadmium composition on the deposited morphology was also investigated. The size dependent blue shift in the experimentally determined absorption edge has been compared with the theoretical predictions based on the effective mass approximation and tight binding approximation. It is shown that the experimentally determined absorption edges depart from the theoretically calculated values.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Gas sensing based on detection of light radiation from a region of modified cladding (nanocrystalline ZnO) of an optical fiber

Science.gov (United States)

Devendiran, S.; Sastikumar, D.

2017-03-01

A new type of fiber optic gas sensor is proposed by detecting a light radiated from a region of cladding modified with metal oxide (nanocrystalline ZnO). The intensity of radiated light is found to vary with different gasses and concentrations. Sensing characteristics are studied for ammonia, methanol, ethanol and acetone gasses. Gas sensitivity of the proposed sensor is compared with clad-modified fiber optic gas sensor. The new sensor exhibits enhanced sensitivity. Time response characteristics of the sensor are reported.

Enhancement of the corrosion protection of electroless Ni–P coating by deposition of sonosynthesized ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sharifalhoseini, Zahra [Sonochemical Research Center, Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, 91779 Mashhad (Iran, Islamic Republic of); Entezari, Mohammad H., E-mail: entezari@um.ac.ir [Sonochemical Research Center, Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, 91779 Mashhad (Iran, Islamic Republic of); Environmental Chemistry Research Center, Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, 91779 Mashhad (Iran, Islamic Republic of)

2015-10-01

Graphical abstract: Enhancement of the corrosion protection of electroless Ni–P layer by ZnO nanoparticles deposition and the comparison with the classical and sonochemical Ni–P coatings. - Highlights: • Unique effects of ultrasound were investigated on the anticorrosive performance of electroless Ni–P coating. • Sonoynthesis of ZnO NPs and its deposition were performed on the surface of Ni–P coating. • ZnO as an anticorrosive has a critical role in the multifunctional surfaces. • Electrochemical properties of all fabricated samples were compared with each other. - Abstract: Ni–P coatings were deposited through electroless nickel plating in the presence and absence of ultrasound. The simultaneous synthesis of ZnO nanoparticle and its deposition under ultrasound were also carried out on the surface of Ni–P layer prepared by the classical method. The morphology of the surfaces and the chemical composition were determined by scanning electron microscopy(SEM) and energy dispersive spectroscopy (EDS), respectively. Electrochemical techniques were applied for the corrosion behavior studies. The Ni–P layer deposited by ultrasound showed a higher anticorrosive property than the layer deposited by the classical method. The ZnO nanoparticles deposited on the surface of Ni–P layer significantly improved the corrosion resistance.

ZnO thin films on single carbon fibres fabricated by Pulsed Laser Deposition (PLD)

Energy Technology Data Exchange (ETDEWEB)

Krämer, André; Engel, Sebastian [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Sangiorgi, Nicola [Institute of Science and Technology for Ceramics – National Research Council of Italy (CNR-ISTEC), via Granarolo 64, 48018 Faenza, RA (Italy); Department of Chemical Science and Technologies, University of Rome Tor Vergata, via della Ricerca Scientifica, 00133 Rome (Italy); Sanson, Alessandra [Institute of Science and Technology for Ceramics – National Research Council of Italy (CNR-ISTEC), via Granarolo 64, 48018 Faenza, RA (Italy); Bartolomé, Jose F. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), C/Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain); Gräf, Stephan, E-mail: stephan.graef@uni-jena.de [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Müller, Frank A. [Otto Schott Institute of Materials Research (OSIM), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany); Center for Energy and Environmental Chemistry Jena (CEEC Jena), Friedrich Schiller University Jena, Philosophenweg 7a, 07743 Jena (Germany)

2017-03-31

Highlights: • Carbon fibres were entirely coated with thin films consisting of aligned ZnO crystals. • A Q-switched CO2 laser was utilised as radiation source. • Suitability of ZnO thin films on carbon fibres as photo anodes for DSSC was studied. - Abstract: Single carbon fibres were 360° coated with zinc oxide (ZnO) thin films by pulsed laser deposition using a Q-switched CO{sub 2} laser with a pulse duration τ ≈ 300 ns, a wavelength λ = 10.59 μm, a repetition frequency f{sub rep} = 800 Hz and a peak power P{sub peak} = 15 kW in combination with a 3-step-deposition technique. In a first set of experiments, the deposition process was optimised by investigating the crystallinity of ZnO films on silicon and polished stainless steel substrates. Here, the influence of the substrate temperature and of the oxygen partial pressure of the background gas were characterised by scanning electron microscopy and X-ray diffraction analyses. ZnO coated carbon fibres and conductive glass sheets were used to prepare photo anodes for dye-sensitised solar cells in order to investigate their suitability for energy conversion devices. To obtain a deeper insight of the electronic behaviour at the interface between ZnO and substrate I–V measurements were performed.

Structural, Optical, and Vibrational Properties of ZnO Microrods Deposited on Silicon Substrate

Science.gov (United States)

Lahlouh, Bashar I.; Ikhmayies, Shadia J.; Juwhari, Hassan K.

2018-03-01

Zinc oxide (ZnO) microrod films deposited by spray pyrolysis on silicon substrate at 350 ± 5°C have been studied and evaluated, and compared with thin films deposited by electron beam to confirm the identity of the studied samples. The films were characterized using different techniques. The microrod structure was studied and confirmed by scanning electron microscopy. Fourier-transform infrared (FTIR) spectroscopy and x-ray diffraction analysis confirmed successful deposition of ZnO thin films with the expected wurtzite structure. Reflectance data showed a substantial drop across the whole studied wavelength range. The photoluminescence (PL) spectra of the studied samples showed a peak at ˜ 360 nm, representing a signature of ZnO. The shift in the PL peak position is due to defects and other species present in the films, as confirmed by FTIR and energy-dispersive x-ray spectroscopy results.

Structural, optical and magnetic properties of nanocrystalline Co-doped ZnO thin films grown by sol-gel

Energy Technology Data Exchange (ETDEWEB)

Kayani, Zohra Nazir; Shah, Iqra; Zulfiqar, Bareera; Sabah, Aneeqa [Lahore College for Women Univ., Lahore (Pakistan); Riaz, Saira; Naseem, Shahzad [Univ. of the Punjab, Lahore (Pakistan). Centre of Excellence in Solid State Physics

2018-04-01

Cobalt-doped ZnO thin films have been deposited using a sol-gel route by changing the number of coats on the substrate from 6 to 18. This project deals with various film thicknesses by increasing the number of deposited coats. The effect of thickness on structural, magnetic, surface morphology and optical properties of Co-doped ZnO thin film was studied. The crystal structure of the Co-doped ZnO films was investigated by X-ray diffraction. The films have polycrystalline wurtzite hexagonal structures. A Co{sup 2+} ion takes the place of a Zn{sup 2+} ion in the lattice without creating any distortion in its hexagonal wurtzite structure. An examination of the optical transmission spectra showed that the energy band gap of the Co-doped ZnO films increased from 3.87 to 3.97 eV with an increase in the number of coatings on the substrate. Ferromagnetic behaviour was confirmed by measurements using a vibrating sample magnetometer. The surface morphology of thin films was assessed by scanning electron microscope. The grain size on the surface of thin films increased with an increase in the number of coats.

Effect of the electrochemical technique on nanocrystalline ZnO electrodeposition, its structural, morphological and photoelectrochemical properties

Energy Technology Data Exchange (ETDEWEB)

Chettah, Hamdane; Abdi, Djamila, E-mail: naimadjam@hotmail.com

2013-06-30

This article reports the influence of the electrochemical technique on the electrodeposition of nanoscopic zinc oxide from aqueous mixed bath of zinc nitrate and potassium chloride at 70 °C onto fluorine doped tin oxide coated glass substrates. ZnO thin films were elaborated via cyclic voltamperometry and chronoamperometry techniques. This study shows structural and morphological differences in films deposited according to both methods. Thin and adherent films obtained via cyclic voltamperometry have been obtained after 100 cycles, and those obtained using the chronoampermetric method grown at potential of − 1 V vs. Ag/AgCl during 1 h. The structural characterisation of such films was performed using X-ray diffraction, which showed the most important peaks of ZnO wurtzite structure with preferential orientation along the (002) axis for deposits obtained via cyclic voltamperometry presenting nanometric grain sizes (42 nm). Atomic force microscopy was used to study surface morphology and estimate the surface roughness factor for two deposits. Photoelectrochemical study indicates that both kinds of films had n-type electrical conductivity and presents high photoanodic-generated currents. - Highlights: • Zinc oxide films were electrodeposited on fluorine doped tin oxide substrates at 70 °C. • Two electrochemical techniques were used cyclic voltamperometry and chronoamperometry. • X-ray diffraction showed the most important peaks of ZnO wurtzite structure. • Preferential orientation along the (002) axis for cyclic voltamperometry films. • Deposits had n-type electrical conductivity and high photoanodic-generated currents.

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Optical and mechanical properties of nanocrystalline ZrC thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Craciun, D., E-mail: doina.craciun@inflpr.ro [Laser Department, National Institute for Laser, Plasma, and Radiation Physics, Magurele (Romania); Socol, G. [Laser Department, National Institute for Laser, Plasma, and Radiation Physics, Magurele (Romania); Lambers, E. [Major Analytical Instrumentation Center, College of Engineering, University of Florida, Gainesville, FL 32611 (United States); McCumiskey, E.J.; Taylor, C.R. [Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States); Martin, C. [Ramapo College of New Jersey (United States); Argibay, N. [Materials Science and Engineering Center, Sandia National Laboratories, Albuquerque, NM 87123 (United States); Tanner, D.B. [Physics Department, University of Florida, Gainesville, FL 32611 (United States); Craciun, V. [Laser Department, National Institute for Laser, Plasma, and Radiation Physics, Magurele (Romania)

2015-10-15

Highlights: • Nanocrystalline ZrC thin film were grown on Si by pulsed laser deposition technique. • Structural properties weakly depend on the CH{sub 4} pressure used during deposition. • The optimum deposition pressure for low resistivity is around 2 × 10{sup −5} mbar CH{sub 4}. • ZrC films exhibited friction coefficients around 0.4 and low wear rates. - Abstract: Thin ZrC films (<500 nm) were grown on (100) Si substrates at a substrate temperature of 500 °C by the pulsed laser deposition (PLD) technique using a KrF excimer laser under different CH{sub 4} pressures. Glancing incidence X-ray diffraction showed that films were nanocrystalline, while X-ray reflectivity studies found out films were very dense and exhibited a smooth surface morphology. Optical spectroscopy data shows that the films have high reflectivity (>90%) in the infrared region, characteristic of metallic behavior. Nanoindentation results indicated that films deposited under lower CH{sub 4} pressures exhibited slightly higher nanohardness and Young modulus values than films deposited under higher pressures. Tribological characterization revealed that these films exhibited relatively high wear resistance and steady-state friction coefficients on the order of μ = 0.4.

In situ formation deposited ZnO nanoparticles on silk fabrics under ultrasound irradiation.

Science.gov (United States)

Khanjani, Somayeh; Morsali, Ali; Joo, Sang W

2013-03-01

Deposition of zinc(II) oxide (ZnO) nanoparticles on the surface of silk fabrics was prepared by sequential dipping steps in alternating bath of potassium hydroxide and zinc nitrate under ultrasound irradiation. This coating involves in situ generation and deposition of ZnO in a one step. The effects of ultrasound irradiation, concentration and sequential dipping steps on growth of the ZnO nanoparticles have been studied. Results show a decrease in the particles size as increasing power of ultrasound irradiation. Also, increasing of the concentration and sequential dipping steps increase particle size. The physicochemical properties of the nanoparticles were determined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and wavelength dispersive X-ray (WDX). Copyright © 2012 Elsevier B.V. All rights reserved.

Annealing Temperature Dependence of ZnO Nanostructures Grown by Facile Chemical Bath Deposition for EGFET pH Sensors

Science.gov (United States)

Bazilah Rosli, Aimi; Awang, Zaiki; Sobihana Shariffudin, Shafinaz; Herman, Sukreen Hana

2018-03-01

Zinc Oxide (ZnO) nanostructures were deposited using chemical bath deposition (CBD) technique in water bath at 95 °C for 4 h. Post-deposition heat treatment in air ambient at various temperature ranging from 200-600 °C for 30 min was applied in order to enhance the electrical properties of ZnO nanostructures as the sensing membrane of extended-gate field effect transistor (EGFET) pH sensor. The as-deposited sample was prepared for comparison. The samples were characterized in terms of physical and sensing properties. FESEM images showed that scattered ZnO nanorods were formed for the as-deposited sample, and the morphology of the ZnO nanorods changed to ZnO nanoflowers when the heat treatment was applied from 200-600 °C. For sensing properties, the samples heated at 300 °C showed the higher sensitivity which was 39.9 mV/pH with the linearity of 0.9792. The sensing properties was increased with the increasing annealing treatment temperature up to 300 °C before decreased drastically.

Near band edge emission characteristics of sputtered nano-crystalline ZnO films

International Nuclear Information System (INIS)

Kunj, Saurabh; Sreenivas, K.

2016-01-01

Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O_2) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

Near band edge emission characteristics of sputtered nano-crystalline ZnO films

Science.gov (United States)

Kunj, Saurabh; Sreenivas, K.

2016-05-01

Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O2) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

Near band edge emission characteristics of sputtered nano-crystalline ZnO films

Energy Technology Data Exchange (ETDEWEB)

Kunj, Saurabh; Sreenivas, K. [Department of Physics & Astrophysics, University of Delhi, Delhi 110007 INDIA (India)

2016-05-06

Sputtered zinc oxide (ZnO) thin films deposited on unheated glass substrate under different sputtering gas mixtures (Ar+O{sub 2}) have been investigated using X-ray diffraction and photo luminescence spectroscopy. Earlier reported studies on ZnO films prepared by different techniques exhibit either a sharp/broad near band edge (NBE) emission peak depending on the crystalline quality of the film. In the present study zinc oxide films, grown on unheated substrates, are seen to possess a preferred (002) orientation with a microstructure consisting of clustered nano-sized crystallites. The splitting in the near band edge emission (NBE) into three characteristic peaks is attributed to quantum confinement effect, and is observed specifically under an excitation of 270 nm. Deep level emission (DLE) in the range 400 to 700 nm is not observed indicating absence of deep level radiative defects.

Granular nanocrystalline zirconia electrolyte layers deposited on porous SOFC cathode substrates

International Nuclear Information System (INIS)

Seydel, Johannes; Becker, Michael; Ivers-Tiffee, Ellen; Hahn, Horst

2009-01-01

Thin granular yttria-stabilized zirconia (YSZ) electrolyte layers were prepared by chemical vapor synthesis and deposition (CVD/CVS) on a porous substoichiometric lanthanum-strontium-manganite (ULSM) solid oxide fuel cell cathode substrate. The substrate porosity was optimized with a screen printed fine porous buffer layer. Structural analysis by scanning electron microscopy showed a homogeneous, granular nanocrystalline layer with a microstructure that was controlled via reactor settings. The CVD/CVS gas-phase process enabled the deposition of crack-free granular YSZ films on porous ULSM substrates. The electrolyte layers characterized with impedance spectroscopy exhibited enhanced grain boundary conductivity.

Characterization and device applications of ZnO films deposited by high power impulse magnetron sputtering (HiPIMS)

Science.gov (United States)

Partridge, J. G.; Mayes, E. L. H.; McDougall, N. L.; Bilek, M. M. M.; McCulloch, D. G.

2013-04-01

ZnO films have been reactively deposited on sapphire substrates at 300 °C using a high impulse power magnetron sputtering deposition system and characterized structurally, optically and electronically. The unintentionally doped n-type ZnO films exhibit high transparency, moderate carrier concentration (˜5 × 1018 cm-3) and a Hall mobility of 8.0 cm2 V-1 s-1, making them suitable for electronic device applications. Pt/ZnO Schottky diodes formed on the HiPIMS deposited ZnO exhibited rectification ratios up to 104 at ±2 V and sensitivity to UV light.

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

Science.gov (United States)

Klingsporn, M.; Kirner, S.; Villringer, C.; Abou-Ras, D.; Costina, I.; Lehmann, M.; Stannowski, B.

2016-06-01

Nanocrystalline silicon suboxides (nc-SiOx) have attracted attention during the past years for the use in thin-film silicon solar cells. We investigated the relationships between the nanostructure as well as the chemical, electrical, and optical properties of phosphorous, doped, nc-SiO0.8:H fabricated by plasma-enhanced chemical vapor deposition. The nanostructure was varied through the sample series by changing the deposition pressure from 533 to 1067 Pa. The samples were then characterized by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, Raman spectroscopy, aberration-corrected high-resolution transmission electron microscopy, selected-area electron diffraction, and a specialized plasmon imaging method. We found that the material changed with increasing pressure from predominantly amorphous silicon monoxide to silicon dioxide containing nanocrystalline silicon. The nanostructure changed from amorphous silicon filaments to nanocrystalline silicon filaments, which were found to cause anisotropic electron transport.

Preparation and characterization of ALD deposited ZnO thin films studied for gas sensors

Energy Technology Data Exchange (ETDEWEB)

Boyadjiev, S.I., E-mail: boiajiev@gmail.com [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Georgieva, V. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Yordanov, R. [Department of Microelectronics, Technical University of Sofia, 8 Kliment Ohridski Blvd., 1756 Sofia (Bulgaria); Raicheva, Z. [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Szilágyi, I.M. [MTA-BME Technical Analytical Chemistry Research Group, Szent Gellért tér 4, Budapest, H-1111 (Hungary); Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry, Szent Gellért tér 4, Budapest, H-1111 (Hungary)

2016-11-30

Highlights: • For the first time the gas sensing towards NO{sub 2} of very thin ALD ZnO films is studied. • The very thin ALD ZnO films showed excellent sensitivity to NO{sub 2} at room temperature. • These very thin film ZnO-based QCM sensors very well register even low concentrations. • The sensors have fully reversible sorption and are able to be recovered in short time. • Described fast and cost-effective ALD deposition of ZnO thin films for QCM gas sensor. - Abstract: Applying atomic layer deposition (ALD), very thin zinc oxide (ZnO) films were deposited on quartz resonators, and their gas sensing properties were studied using the quartz crystal microbalance (QCM) method. The gas sensing of the ZnO films to NO{sub 2} was tested in the concentration interval between 10 and 5000 ppm. On the basis of registered frequency change of the QCM, for each concentration the sorbed mass was calculated. Further characterization of the films was carried out by various techniques, i.e. by SEM-EDS, XRD, ellipsometry, and FTIR spectroscopy. Although being very thin, the films were gas sensitive to NO{sub 2} already at room temperature and could register very well as low concentrations as 100 ppm, while the sorption was fully reversible. Our results for very thin ALD ZnO films show that the described fast, simple and cost-effective technology could be implemented for producing gas sensors working at room temperature and being capable to detect in real time low concentrations of NO{sub 2}.

Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

DEFF Research Database (Denmark)

Sun, Jie; Lindvall, Niclas; Cole, Matthew T.

2012-01-01

Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinholes...

Characterization of homoepitaxial and heteroepitaxial ZnO films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Chen, Z.Q. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)]. E-mail: chenzq@taka.jaeri.go.jp; Yamamoto, S. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Kawasuso, A. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Xu, Y. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Sekiguchi, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

2005-05-15

Homo- and heteroepitaxial ZnO films were grown on ZnO (0001) and Al{sub 2}O{sub 3} (1-bar 1-bar 2-bar -bar 0) substrates by using pulsed laser deposition. The X-ray diffraction and Raman measurements for these films show good correspondence with the bulk ZnO substrate, which confirms successful growth of c-axis oriented ZnO layer. Strong UV emission was also observed in these films, indicating good optical quality. However, the surface roughness differs very much for the homo- and heteroepitaxial film, that is, much less for the homoepitaxial layer. Positron annihilation measurements reveal a higher vacancy concentration in the homoepitaxial layer.

Boron doped nanostructure ZnO films deposited by ultrasonic spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Karakaya, Seniye, E-mail: seniyek@ogu.edu.tr; Ozbas, Omer

2015-02-15

Highlights: • Nanostructure undoped and boron doped ZnO films were deposited by USP technique. • Influences of doping on the surface and optical properties of the ZnO films were investigated. • XRD spectra of the films exhibited a variation in crystalline quality depending on the B content. - Abstract: ZnO is an II–VI compound semiconductor with a wide direct band gap of 3.3 eV at room temperature. Doped with group III elements (B, Al or Ga), it becomes an attractive candidate to replace tin oxide (SnO{sub 2}) or indium tin oxide (ITO) as transparent conducting electrodes in solar cell devices and flat panel display due to competitive electrical and optical properties. In this work, ZnO and boron doped ZnO (ZnO:B) films have been deposited onto glass substrates at 350 ± 5 °C by a cost-efficient ultrasonic spray pyrolysis technique. The optical, structural, morphological and electrical properties of nanostructure undoped and ZnO:B films have been investigated. Electrical resistivity of films has been analyzed by four-probe technique. Optical properties and thicknesses of the films have been examined in the wavelength range 1200–1600 nm by using spectroscopic ellipsometry (SE) measurements. The optical constants (refractive index (n) and extinction coefficient (k)) and the thicknesses of the films have been fitted according to Cauchy model. The optical method has been used to determine the band gap value of the films. Transmission spectra have been taken by UV spectrophotometer. It is found that both ZnO and ZnO:B films have high average optical transmission (≥80%). X-ray diffraction (XRD) patterns indicate that the obtained ZnO has a hexagonal wurtzite type structure. The morphological properties of the films were studied by atomic force microscopy (AFM). The surface morphology of the nanostructure films is found to depend on the concentration of B. As a result, ZnO:B films are promising contender for their potential use as transparent window layer and

CdTe deposition by successive ionic layer adsorption and reaction (SILAR) technique onto ZnO nanowires

Energy Technology Data Exchange (ETDEWEB)

Salazar, Raul; Delamoreanu, Alexandru; Saidi, Bilel; Ivanova, Valentina [CEA, LETI, MINATEC Campus, 17 Rue des Martyrs, 38054, Grenoble (France); Levy-Clement, Claude [CNRS, Institut de Chimie et des Materiaux de Paris-Est, 94320, Thiais (France)

2014-09-15

In this study is reported CdTe deposition by Successive Ionic Layer Adsorption and reaction (SILAR) at room temperature onto ZnO nanowires (NWs). The as-deposited CdTe layer exhibits poor crystalline quality and not well defined optical transition which is probably result of its amorphous nature. The implementation of an annealing step and chemical treatment by CdCl{sub 2} to the classical SILAR technique improved significantly the CdTe film quality. The XRD analysis showed that the as treated layers are crystallized in the cubic zinc blende structure. The full coverage of ZnO nanowires and thickness of the CdTe shell, composed of small crystallites, was confirmed by STEM and TEM analysis. The layer thickness could be controlled by the number of SILAR cycles. The sharper optical transitions for the annealed and CdCl{sub 2} treated heterostructures additionally proves the enhancement of the layer crystalline quality. For comparison CdTe was also deposited by close space sublimation (CSS) method onto ZnO nanowires. It is shown that the SILAR deposited CdTe exhibits equal crystalline and optical properties to that prepared by CSS. These results demonstrate that SILAR technique is more suitable for conformal thin film deposition on nanostructures. CdTe extremely thin film deposited by SILAR method onto ZnO nanowire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

CdTe deposition by successive ionic layer adsorption and reaction (SILAR) technique onto ZnO nanowires

International Nuclear Information System (INIS)

Salazar, Raul; Delamoreanu, Alexandru; Saidi, Bilel; Ivanova, Valentina; Levy-Clement, Claude

2014-01-01

In this study is reported CdTe deposition by Successive Ionic Layer Adsorption and reaction (SILAR) at room temperature onto ZnO nanowires (NWs). The as-deposited CdTe layer exhibits poor crystalline quality and not well defined optical transition which is probably result of its amorphous nature. The implementation of an annealing step and chemical treatment by CdCl 2 to the classical SILAR technique improved significantly the CdTe film quality. The XRD analysis showed that the as treated layers are crystallized in the cubic zinc blende structure. The full coverage of ZnO nanowires and thickness of the CdTe shell, composed of small crystallites, was confirmed by STEM and TEM analysis. The layer thickness could be controlled by the number of SILAR cycles. The sharper optical transitions for the annealed and CdCl 2 treated heterostructures additionally proves the enhancement of the layer crystalline quality. For comparison CdTe was also deposited by close space sublimation (CSS) method onto ZnO nanowires. It is shown that the SILAR deposited CdTe exhibits equal crystalline and optical properties to that prepared by CSS. These results demonstrate that SILAR technique is more suitable for conformal thin film deposition on nanostructures. CdTe extremely thin film deposited by SILAR method onto ZnO nanowire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Defect studies of ZnO films prepared by pulsed laser deposition on various substrates

International Nuclear Information System (INIS)

Melikhova, O; Čížek, J; Procházka, I; Kužel, R; Novotný, M; Bulír, J; Lancok, J; Anwand, W; Brauer, G; Connolly, J; McCarthy, E; Krishnamurthy, S; Mosnier, J-P

2013-01-01

ZnO thin films deposited on various substrates were characterized by slow positron implantation spectroscopy (SPIS) combined with X-ray diffraction (XRD). All films studied exhibit wurtzite structure and crystallite size 20–100 nm. The mosaic spread of crystallites is relatively small for the films grown on single crystalline substrates while it is substantial for the film grown on amorphous substrate. SPIS investigations revealed that ZnO films deposited on single crystalline substrates exhibit significantly higher density of defects than the film deposited on amorphous substrate. This is most probably due to a higher density of misfit dislocations, which compensate for the lattice mismatch between the film and the substrate.

Pure and Sn-doped ZnO films produced by pulsed laser deposition

DEFF Research Database (Denmark)

Holmelund, E.; Schou, Jørgen; Tougaard, S.

2002-01-01

A new technique, metronome doping, has been used for doping of films during pulsed laser deposition (PLD). This technique makes it possible to dope continuously during film growth with different concentrations of a dopant in one deposition sequence. Films of pure and doped ZnO have been produced...

Synthesis and characterization of nanocrystalline zinc ferrite

DEFF Research Database (Denmark)

Jiang, J.S.; Yang, X.L.; Gao, L.

1999-01-01

Nanocrystalline zinc ferrite powders with a partially inverted spinel structure were synthesized by high-energy ball milling in a closed container at ambient temperature from a mixture of alpha-Fe2O3 and ZnO crystalline powders in equimolar ratio. From low-temperature and in-field Mossbauer...

Low-temperature deposition of ZnO thin films on PET and glass substrates by DC-sputtering technique

International Nuclear Information System (INIS)

Banerjee, A.N.; Ghosh, C.K.; Chattopadhyay, K.K.; Minoura, Hideki; Sarkar, Ajay K.; Akiba, Atsuya; Kamiya, Atsushi; Endo, Tamio

2006-01-01

The structural, optical and electrical properties of ZnO thin films (260 - 490 nm thick) deposited by direct-current sputtering technique, at a relatively low-substrate temperature (363 K), onto polyethylene terephthalate and glass substrates have been investigated. X-ray diffraction patterns confirm the proper phase formation of the material. Optical transmittance data show high transparency (80% to more than 98%) of the films in the visible portion of solar radiation. Slight variation in the transparency of the films is observed with a variation in the deposition time. Electrical characterizations show the room-temperature conductivity of the films deposited onto polyethylene terephthalate substrates for 4 and 5 h around 0.05 and 0.25 S cm -1 , respectively. On the other hand, for the films deposited on glass substrates, these values are 8.5 and 9.6 S cm -1 for similar variation in the deposition time. Room-temperature conductivity of the ZnO films deposited on glass substrates is at least two orders of magnitude higher than that of ZnO films deposited onto polyethylene terephthalate substrates under identical conditions. Hall-measurements show the maximum carrier concentration of the films on PET and glass substrate around 2.8 x 10 16 and 3.1 x 10 2 cm -3 , respectively. This report will provide newer applications of ZnO thin films in flexible display technology

Synthesis and Characterization of Molybdenum Doped ZnO Thin Films by SILAR Deposition Method

Science.gov (United States)

Radha, R.; Sakthivelu, A.; Pradhabhan, D.

2016-08-01

Molybdenum (Mo) doped zinc oxide (ZnO) thin films were deposited on the glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) deposition method. The effect of Mo dopant concentration of 5, 6.6 and 10 mol% on the structural, morphological, optical and electrical properties of n-type Mo doped ZnO films was studied. The X-ray diffraction (XRD) results confirmed that the Mo doped ZnO thin films were polycrystalline with wurtzite structure. The field emission scanning electron microscopy (FESEM) studies shows that the surface morphology of the films changes with Mo doping. A blue shift of the optical band gap was observed in the optical studies. Effect of Mo dopant concentration on electrical conductivity was studied and it shows comparatively high electrical conductivity at 10 mol% of Mo doping concentration.

Cycling behaviour of sponge-like nanostructured ZnO as thin-film Li-ion battery anodes

International Nuclear Information System (INIS)

Garino, Nadia; Lamberti, Andrea; Gazia, Rossana; Chiodoni, Angelica; Gerbaldi, Claudio

2014-01-01

Highlights: • Zn is thermally oxidized in ambient air to obtain sponge-like ZnO film. • Polycrystalline, transparent, porous thin film is obtained. • Film exhibits stabile specific capacity (∼300 mAh g −1 ) after prolonged cycling. • Sponge-like ZnO film shows promising prospects as Li-ion battery anode. - Abstract: Single phase wurtzitic porous ZnO thin films are obtained by a simple two-step method, involving the sputtering deposition of a sponge-like metallic Zn layer, followed by a moderately low temperature treatment for the complete zinc oxidation. Thanks to its 3D nanostructuration, the superimposition of small branches able to grow in length almost isotropically and forming a complex topography, sponge-like ZnO can combine the fast transport properties of one dimensional material and the high surface area usually provided by nanocrystalline electrodes. When galvanostatically tested in lithium cell, after the initial decay, it can provide an almost stable specific capacity higher than 50 μAh cm −2 after prolonged cycling at estimated 0.7 C, with very high Coulombic efficiency

Cycling behaviour of sponge-like nanostructured ZnO as thin-film Li-ion battery anodes

Energy Technology Data Exchange (ETDEWEB)

Garino, Nadia, E-mail: nadia.garino@iit.it [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Lamberti, Andrea; Gazia, Rossana; Chiodoni, Angelica [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); Gerbaldi, Claudio, E-mail: claudio.gerbaldi@polito.it [Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento, 21, 10129 Turin (Italy); GAME Lab, Department of Applied Science and Technology – DISAT, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Turin (Italy)

2014-12-05

Highlights: • Zn is thermally oxidized in ambient air to obtain sponge-like ZnO film. • Polycrystalline, transparent, porous thin film is obtained. • Film exhibits stabile specific capacity (∼300 mAh g{sup −1}) after prolonged cycling. • Sponge-like ZnO film shows promising prospects as Li-ion battery anode. - Abstract: Single phase wurtzitic porous ZnO thin films are obtained by a simple two-step method, involving the sputtering deposition of a sponge-like metallic Zn layer, followed by a moderately low temperature treatment for the complete zinc oxidation. Thanks to its 3D nanostructuration, the superimposition of small branches able to grow in length almost isotropically and forming a complex topography, sponge-like ZnO can combine the fast transport properties of one dimensional material and the high surface area usually provided by nanocrystalline electrodes. When galvanostatically tested in lithium cell, after the initial decay, it can provide an almost stable specific capacity higher than 50 μAh cm{sup −2} after prolonged cycling at estimated 0.7 C, with very high Coulombic efficiency.

Growth and characterization of polar and nonpolar ZnO film grown on sapphire substrates by using atomic layer deposition

International Nuclear Information System (INIS)

Kim, Ki-Wook; Son, Hyo-Soo; Choi, Nak-Jung; Kim, Jihoon; Lee, Sung-Nam

2013-01-01

We investigated the electrical and the optical properties of polar and nonpolar ZnO films grown on sapphire substrates with different crystallographic planes. High resolution X-ray results revealed that polar c-plane (0001), nonpolar m-plane (10-10) and a-plane (11-20) ZnO thin films were grown on c-plane, m- and r-sapphire substrates by atomic layer deposition, respectively. Compared with the c-plane ZnO film, nonpolar m-plane and a-plane ZnO films showed smaller surface roughness and anisotropic surface structures. Regardless of ZnO crystal planes, room temperature photoluminescence spectra represented two emissions which consisted of the near bandedge (∼ 380 nm) and the deep level emission (∼ 500 nm). The a-plane ZnO films represented better optical and electrical properties than c-plane ZnO, while m-plane ZnO films exhibited poorer optical and electrical properties than c-plane ZnO. - Highlights: • Growth and characterization of a-, c- and m-plane ZnO film by atomic layer deposition. • The a-plane ZnO represented better optical and electrical properties than c-plane ZnO. • The m-plane ZnO exhibited poorer optical and electrical properties than c-plane ZnO

Microstructure and optical properties of nanocrystalline ZnO and ZnO:(Li or Al) thin films

Energy Technology Data Exchange (ETDEWEB)

Oral, A. Yavuz [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey)]. E-mail: aoral@gyte.edu.tr; Bahsi, Z. Banu [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze 41400 (Turkey); Aslan, M. Hasan [Department of Physics, Gebze Institute of Technology, Gebze 41400 (Turkey)

2007-03-15

Zinc oxide thin films (ZnO, ZnO:Li, ZnO:Al) were deposited on glass substrates by a sol-gel technique. Zinc acetate, lithium acetate, and aluminum chloride were used as metal ion sources in the precursor solutions. XRD analysis revealed that Li doped and undoped ZnO films formed single phase zincite structure in contrast to Al:ZnO films which did not fully crystallize at the annealing temperature of 550 deg. C. Crystallized films had a grain size under 50 nm and showed c-axis grain orientation. All films had a very smooth surface with RMS surface roughness values between 0.23 and 0.35 nm. Surface roughness and optical band tail values increased by Al doping. Compared to undoped ZnO films, Li doping slightly increased the optical band gap of the films.

Parametric study of self-forming ZnO Nanowall network with honeycomb structure by Pulsed Laser Deposition

KAUST Repository

El Zein, B.

2014-02-01

The successful synthesis of catalyst free zinc oxide (ZnO) Nanowall networks with honeycomb like structure by Pulsed Laser Deposition (PLD) is demonstrated in this paper. The synthesis was conducted directly on Silicon (Si) (1 0 0) and Glass-ITO substrates without the intermediate of metal catalyst, template or chemical etching. Kinetic of growth and effects of gas pressure and substrate temperature were studied by depositing ZnO films on P type Si (1 0 0) substrates with different deposition parameters. The optimized growth parameters were found as: 10 mTorr oxygen pressure, 600 C substrate temperature, and deposition duration equal or higher than 10 min. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Photoluminescence (PL) measurements were used to investigate structural, microstructural and optical properties of ZnO Nanowall networks produced. They exhibit a non-uniform size high quality honeycomb structure with low deep level defects. © 2013 Elsevier B.V.

Photoelectrochemical water splitting under visible light over anti-photocorrosive In2O3-coupling ZnO nanorod arrays photoanode

International Nuclear Information System (INIS)

Zhang, Yan; Zhang, Jinqiu; Nie, Mengyan; Sun, Kai; Li, Chunhu; Yu, Jianqiang

2015-01-01

In 2 O 3 quantum dots with a high crystallinity were deposited on the surface of ZnO nanorods through a chemistry bath method. The resulting In 2 O 3 -sensitizing ZnO nanorod arrays not only exhibited enhanced photoelectrochemical activity for water splitting under visible-light irradiation, but also possessed anti-photocorrosion property. The photo-induced charge-transfer property of In 2 O 3 could be improved greatly by coupling with ZnO. This observation demonstrated that the heterojunction at the interface between In 2 O 3 and ZnO could efficiently reduce the recombination of photo-induced electron–hole pairs and increase the lifetime of charge carriers and therefore enhance the photo-to-current efficiency of the In 2 O 3 –ZnO nanocrystalline arrays. It reveals that the heterojunction construction between two different semiconductors plays a very important role in determining the dynamic properties of their photogenerated charge carriers and their photo-to-current conversion efficiency

Non-vacuum, single-step conductive transparent ZnO patterning by ultra-short pulsed laser annealing of solution-deposited nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lee, Daeho; Pan, Heng; Kim, Eunpa; Grigoropoulos, Costas P. [University of California, Department of Mechanical Engineering, Berkeley, CA (United States); Ko, Seung Hwan [Korea Advanced Institute of Science and Technology (KAIST), Department of Mechanical Engineering, Daejeon (Korea, Republic of); Park, Hee K. [AppliFlex LLC, Sunnyvale, CA (United States)

2012-04-15

A solution-processable, high-concentration transparent ZnO nanoparticle (NP) solution was successfully synthesized in a new process. A highly transparent ZnO thin film was fabricated by spin coating without vacuum deposition. Subsequent ultra-short-pulsed laser annealing at room temperature was performed to change the film properties without using a blanket high temperature heating process. Although the as-deposited NP thin film was not electrically conductive, laser annealing imparted a large conductivity increase and furthermore enabled selective annealing to write conductive patterns directly on the NP thin film without a photolithographic process. Conductivity enhancement could be obtained by altering the laser annealing parameters. Parametric studies including the sheet resistance and optical transmittance of the annealed ZnO NP thin film were conducted for various laser powers, scanning speeds and background gas conditions. The lowest resistivity from laser-annealed ZnO thin film was about 4.75 x 10{sup -2} {omega} cm, exhibiting a factor of 10{sup 5} higher conductivity than the previously reported furnace-annealed ZnO NP film and is even comparable to that of vacuum-deposited, impurity-doped ZnO films within a factor of 10. The process developed in this work was applied to the fabrication of a thin film transistor (TFT) device that showed enhanced performance compared with furnace-annealed devices. A ZnO TFT performance test revealed that by just changing the laser parameters, the solution-deposited ZnO thin film can also perform as a semiconductor, demonstrating that laser annealing offers tunability of ZnO thin film properties for both transparent conductors and semiconductors. (orig.)

Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

International Nuclear Information System (INIS)

Nam, Chang-Yong; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

2015-01-01

We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ∼10 19  cm −3 carrier density, and ∼0.1 cm 2 V −1 s −1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices

Electrodeposition of ZnO nano-wires lattices with a controlled morphology; Electrodepot de reseaux de nanofils de ZnO a morphologie controlee

Energy Technology Data Exchange (ETDEWEB)

Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C. [Centre National de la Recherche Scientifique (CNRS), Lab. de Chimie Metallurgique des Terres Rares, UPR 209, 94 - Thiais (France)

2006-07-01

In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO{sub 2}. Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

Fast vertical growth of ZnO nanorods using a modified chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Lee, Tae-hyun [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, Hyukhyun, E-mail: hhryu@inje.ac.kr [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Lee, Won-Jae [Department of Materials and Components Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of)

2014-06-01

Highlights: • We grew vertical ZnO nanorods by a modified CBD process with a fast growth rate. • We studied the effects of the CBD process by varying growth temperature, time, and concentration. • The ZnO nanorods grown by the modified CBD showed good morphological and structural properties. - Abstract: In this study, we grew vertical ZnO nanorods on seeded Si (1 0 0) substrates using a modified chemical bath deposition (CBD). We investigated the effects of the growth temperature, growth time and concentration on the morphological and structural properties of the ZnO nanorods using field emission gun scanning electron microscopy (FEG-SEM) and X-ray diffraction. This modified CBD method shows improved results over conventional CBD. ZnO nanorods with good structural XRD properties were grown with a very fast growth rate in a wide range of growth conditions and did not require post-growth annealing.

Formation mechanisms of metallic Zn nanodots by using ZnO thin films deposited on n-Si substrates

International Nuclear Information System (INIS)

Yuk, J. M.; Lee, J. Y.; Kim, Y.; No, Y. S.; Kim, T. W.; Choi, W. K.

2010-01-01

High-resolution transmission electron microscopy and energy dispersive x-ray spectroscopy results showed that metallic Zn nanodots (NDs) were fabricated through transformation of ZnO thin films by deposition of SiO x on ZnO/n-Si (100) heterostructures. The Zn NDs with various sizes and densities were formed due to the occurrence of the mass diffusion of atoms along the grain boundaries in the ZnO thin films. The fabrication mechanisms of metallic Zn NDs through transformation of ZnO thin films deposited on n-Si substrates are described on the basis of the experimental results.

Facing-target sputtering deposition of ZnO films with Pt ultra-thin layers for gas-phase photocatalytic application

International Nuclear Information System (INIS)

Zhang Zhonghai; Hossain, Md. Faruk.; Arakawa, Takuya; Takahashi, Takakazu

2010-01-01

In this paper, various zinc oxide (ZnO) films are deposited by a versatile and effective dc-reactive facing-target sputtering method. The ratios of Ar to O 2 in the mixture gas are varied from 8:2 to 6:4 at a fixed sputtering pressure of 1.0 Pa. X-ray diffraction, spectrophotometer and scanning electron microscope are used to study the crystal structure, optical property and surface morphology of the as-deposited films. The Pt ultra-thin layer, ∼2 nm thick, is deposited on the surface of ZnO film by dc diode sputtering with a mesh mask controlling the coated area. The photocatalytic activity of ZnO films and Pt-ZnO films is evaluated by decomposition of methanol under UV-vis light irradiation. The variation of photocatalytic activity depends on the ratios of Ar to O 2 , which is mainly attributed to the different grain size and carrier mobility. Though the pure ZnO film normally shows a low gas-phase photocatalytic activity, its activity is significantly enhanced by depositing Pt ultra-thin layer.

Mn{sup 2+} ions distribution in doped sol–gel deposited ZnO films

Energy Technology Data Exchange (ETDEWEB)

Stefan, Mariana, E-mail: mstefan@infim.ro [National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele (Romania); Ghica, Daniela; Nistor, Sergiu V.; Maraloiu, Adrian V. [National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele (Romania); Plugaru, Rodica [National Institute for R & D in Microtechnologies (IMT), Erou Iancu Nicolae Str. 126A, 077190 Bucharest (Romania)

2017-02-28

Highlights: • Several Mn{sup 2+} centers observed by EPR in sol–gel ZnO films. • Mn{sup 2+} ions localized at Zn{sup 2+} sites in ZnO grains and disordered ZnO phase. • Sixfold coordinated Mn{sup 2+} ions localized in inter-grain region. • Aggregated Mn in insular-like regions between ZnO grains in the ZnO:5%Mn film. • Aggregated Mn phase presence and distribution observed by EPR and EDX-STEM. - Abstract: The localization and distribution of the Mn{sup 2+} ions in two sol–gel deposited ZnO films doped with different manganese concentrations were investigated by electron paramagnetic resonance spectroscopy and analytical transmission electron microscopy. In the lightly doped sample the Mn{sup 2+} ions are mainly localized substitutionally at isolated tetrahedrally coordinated Zn{sup 2+} sites in both crystalline ZnO nanograins (34%) and surrounding disordered ZnO (52%). In the highly doped ZnO film, a much smaller proportion of manganese substitutes Zn{sup 2+} in the crystalline and disordered ZnO (10%). The main amount (85%) of manganese aggregates in a secondary phase as an insular-like distribution between the ZnO nanograins. The remaining Mn{sup 2+} ions (14% and 5% at low and high doping levels, respectively) are localized at isolated, six-fold coordinated sites, very likely in the disordered intergrain region. Annealing at 600 °C induced changes in the Mn{sup 2+} ions distribution, reflecting the increase of the ZnO crystallization degree, better observed in the lightly doped sample.

Improving the conductance of ZnO thin film doping with Ti by using a cathodic vacuum arc deposition process

International Nuclear Information System (INIS)

Wu, Chun-Sen; Lin, Bor-Tsuen; Jean, Ming-Der

2011-01-01

The Ti-doped ZnO films compared to un-doped ZnO films were deposited onto Corning XG glass substrates by using a cathodic vacuum arc deposition process in a mixture of oxygen and argon gases. The structural, electrical and optical properties of un-doped and Ti-doped ZnO films have been investigated. When the Ti target power is about 750 W, the incorporation of titanium atoms into zinc oxide films is obviously effective. Additionally, the resistivity of un-doped ZnO films is high and reduces to a value of 3.48 x 10 -3 Ω-cm when Ti is incorporated. The Ti doped in the ZnO films gave rise to the improvement of the conductivity of the films obviously. The Ti-doped ZnO films have > 85% transmittance in a range of 400-700 nm.

Effect of Zn(NO3)2 concentration in hydrothermal-electrochemical deposition on morphology and photoelectrochemical properties of ZnO nanorods

Science.gov (United States)

Yilmaz, Ceren; Unal, Ugur

2016-04-01

Zn(NO3)2 concentration had been reported to be significantly influential on electrodeposition of ZnO structures. In this work, this issue is revisited using hydrothermal-electrochemical deposition (HED). Seedless, cathodic electrochemical deposition of ZnO films is carried out on ITO electrode at 130 °C in a closed glass reactor with varying Zn(NO3)2 concentration. Regardless of the concentration of Zn2+ precursor (0.001-0.1 M) in the deposition solution, vertically aligned 1-D ZnO nanorods are obtained as opposed to electrodepositions at lower temperatures (70-80 °C). We also report the effects of high bath temperature and pressure on the photoelectrochemical properties of the ZnO films. Manipulation of precursor concentration in the deposition solution allows adjustment of the aspect ratio of the nanorods and the degree of texturation along the c-axis; hence photoinduced current density. HED is shown to provide a single step synthesis route to prepare ZnO rods with desired aspect ratio specific for the desired application just by controlling the precursor concentration.

X-ray diffraction study of thermal stress relaxation in ZnO films deposited by magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Conchon, F. [Institut P' , Universite de Poitiers-Ensma-UPR CNRS 3346, 86962 Futuroscope (France); Renault, P.O., E-mail: pierre.olivier.renault@univ-poitiers.f [Institut P' , Universite de Poitiers-Ensma-UPR CNRS 3346, 86962 Futuroscope (France); Le Bourhis, E.; Krauss, C.; Goudeau, P. [Institut P' , Universite de Poitiers-Ensma-UPR CNRS 3346, 86962 Futuroscope (France); Barthel, E.; Grachev, S. Yu.; Sondergard, E. [Lab. Surface du Verre et Interfaces (SVI), UMR 125, 93303 Aubervilliers (France); Rondeau, V.; Gy, R. [Lab. Recherche de Saint-Gobain (SGR), 93303 Aubervilliers (France); Lazzari, R.; Jupille, J. [Institut des Nanosciences de Paris (INSP), UMR 7588, 75015 Paris (France); Brun, N. [Lab. Physique des Solides (LPS), UMR 8502, 91405 Orsay (France)

2010-12-30

X-ray diffraction stress analyses have been performed on two different thin films deposited onto silicon substrate: ZnO and ZnO encapsulated into Si{sub 3}N{sub 4} layers. We showed that both as-deposited ZnO films are in a high compressive stress state. In situ X-ray diffraction measurements inside a furnace revealed a relaxation of the as-grown stresses at temperatures which vary with the atmosphere in the furnace and change with Si{sub 3}N{sub 4} encapsulation. The observations show that Si{sub 3}N{sub 4} films lying on both sides of the ZnO film play an important role in the mechanisms responsible for the stress relaxation during heat treatment. The different temperatures observed for relaxation in ambient and argon atmospheres suggest that the thermally activated stress relaxation may be attributed to a variation of the stoichiometry of the ZnO films. The present observations pave the way to fine tuning of the residual stresses through thermal treatment parameters.

Formation Process of Eosin Y-Adsorbing ZnO Particles by Electroless Deposition and Their Photoelectric Conversion Properties.

Science.gov (United States)

Nagaya, Satoshi; Nishikiori, Hiromasa; Mizusaki, Hideaki; Wagata, Hajime; Teshima, Katsuya

2015-06-03

The thin films consisting of crystalline ZnO particles were prepared on fluorine-doped tin oxide electrodes by electroless deposition. The particles were deposited from an aqueous solution containing zinc nitrate, dimethyamine-borane, and eosin Y at 328 K. As the Pd particles were adsorbed on the substrate, not only the eosin Y monomer but also the dimer and debrominated species were rapidly adsorbed on the spherical ZnO particles, which were aggregated and formed secondary particles. On the other hand, in the absence of the Pd particles, the monomer was adsorbed on the flake-shaped ZnO particles, which vertically grew on the substrate surface and had a high crystallinity. The photoelectric conversion efficiency was higher for the ZnO electrodes containing a higher amount of the monomer during light irradiation.

Improvement of ZnO TCO film growth for photovoltaic devices by reactive plasma deposition (RPD)

International Nuclear Information System (INIS)

Iwata, K.; Sakemi, T.; Yamada, A.; Fons, P.; Awai, K.; Yamamoto, T.; Shirakata, S.; Matsubara, K.; Tampo, H.; Sakurai, K.; Ishizuka, S.; Niki, S.

2005-01-01

Reactive plasma deposition (RPD) is a technique for depositing a thin film on a substrate using a pressure-slope type plasma ion gun. This method offers the advantage of low-ion damage, low deposition temperature, large area deposition and high growth rates. Ga-doped zinc oxide (ZnO) thin film was grown on a moving glass substrate by RPD. Evaporation of very small quantity of tungsten from anode electrode by plasma collision lets the resistivity of grown ZnO transparent conductive oxide (TCO) film to increase. However, no reduction of carrier concentration was observed but only reduction of carrier mobility. It indicates that reduction of evaporation of tungsten from anode electrode induces increase of carrier mobility without any increase of carrier concentration. After installation of an anode cooling system in order to avoid the tungsten evaporation, increase of the mobility (37 cm 2 /Vsec) was observed and the lowest resistivity (2.0x10 -4 no. OMEGAno. cm) film was obtained from large size grown ZnO TCO of 200x200 mm at low growth temperature of 200 deg. C with high growth rate of 24 no. muno. m/h

Structural and Optical Properties of Eu Doped ZnO Nanorods prepared by Pulsed Laser Deposition

KAUST Repository

Alarawi, Abeer

2014-06-23

Nano structured wide band gap semiconductors have attracted attention of many researchers due to their potential electronic and optoelectronic applications. In this thesis, we report successful synthesis of well aligned Eu doped ZnO nano-rods prepared, for the first time to our knowledge, by pulsed laser deposition (PLD) without any catalyst. X-ray diffraction (XRD) patterns shows that these Eu doped ZnO nanorods are grown along the c-axis of ZnO wurtzite structure. We have studied the effect of the PLD growth conditions on forming vertically aligned Eu doped ZnO nanorods. The structural properties of the material are investigated using a -scanning electron microscope (SEM). The PLD parameters must be carefully controlled in order to obtain c-axis oriented ZnO nanorods on sapphire substrates, without the use of any catalyst. The experiments conducted in order to identify the optimal growth conditions confirmed that, by adjusting the target-substrate distance, substrate temperature, laser energy and deposition duration, the nanorod size could be successfully controlled. Most importantly, the results indicated that the photoluminescence (PL) properties reflect the quality of the ZnO nanorods. These parameters can change the material’s structure from one-dimensional to two-dimensional however the laser energy and frequency affect the size and the height of the nanorods; the xygen pressure changes the density of the nanorods.

Defect studies in annealed ZnO by positron annihilation spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sanyal, D; Roy, Tapatee Kundu; Chakrabarti, Mahuya; Dechoudhury, Siddhartha; Bhowmick, Debasis; Chakrabarti, Alok [Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata 700064 (India)

2008-01-30

Coincidence Doppler broadening of the positron annihilation technique has been employed to identify the defects in thermally annealed 'as-received' ZnO and thermally annealed ball-milled nanocrystalline ZnO. Results indicate that a significant amount of oxygen vacancy has been created in ZnO due to annealing at about 500 deg. C and above. The results also indicate that the Zn vacancy created during the ball milling process can be easily removed by annealing the sample at about 500 deg. C and above. The defect characterization has also been correlated with the magnetic properties of ZnO.

Defect studies in annealed ZnO by positron annihilation spectroscopy

International Nuclear Information System (INIS)

Sanyal, D; Roy, Tapatee Kundu; Chakrabarti, Mahuya; Dechoudhury, Siddhartha; Bhowmick, Debasis; Chakrabarti, Alok

2008-01-01

Coincidence Doppler broadening of the positron annihilation technique has been employed to identify the defects in thermally annealed 'as-received' ZnO and thermally annealed ball-milled nanocrystalline ZnO. Results indicate that a significant amount of oxygen vacancy has been created in ZnO due to annealing at about 500 deg. C and above. The results also indicate that the Zn vacancy created during the ball milling process can be easily removed by annealing the sample at about 500 deg. C and above. The defect characterization has also been correlated with the magnetic properties of ZnO

X-ray diffraction analysis of thermally-induced stress relaxation in ZnO films deposited by magnetron sputtering on (100) Si substrates

Energy Technology Data Exchange (ETDEWEB)

Conchon, F., E-mail: florineconchon@gmail.co [Laboratoire de Physique des Materiaux (PHYMAT) UMR 6630, Universite de Poitiers, 86962 Futuroscope-Chasseneuil (France); Renault, P.O.; Goudeau, P.; Le Bourhis, E. [Laboratoire de Physique des Materiaux (PHYMAT) UMR 6630, Universite de Poitiers, 86962 Futuroscope-Chasseneuil (France); Sondergard, E.; Barthel, E.; Grachev, S. [Laboratoire de Surface du Verre et Interfaces (SVI), UMR 125, 93303 Aubervilliers (France); Gouardes, E.; Rondeau, V.; Gy, R. [Laboratoire de Recherche de Saint-Gobain (SGR), 93303 Aubervilliers (France); Lazzari, R.; Jupille, J. [Institut des Nanosciences de Paris (INSP), UMR 7588, 75015 Paris (France); Brun, N. [Laboratoire de Physique des Solides (LPS), UMR 8502, 91405 Orsay (France)

2010-07-01

Residual stresses in sputtered ZnO films on Si are determined and discussed. By means of X-ray diffraction, we show that as-deposited ZnO films are highly compressively stressed. Moreover, a transition of stress is observed as a function of the post-deposition annealing temperature. After an 800 {sup o}C annealing, ZnO films are tensily stressed while ZnO films encapsulated by Si{sub 3}N{sub 4} are stress-free. With the aid of in-situ X-ray diffraction under ambient and argon atmosphere, we argue that this thermally activated stress relaxation may be attributed to a variation of the stoichiometry of the ZnO films.

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}.

A comparative study of ultraviolet photoconductivity relaxation in zinc oxide (ZnO) thin films deposited by different techniques

International Nuclear Information System (INIS)

Yadav, Harish Kumar; Gupta, Vinay

2012-01-01

Photoresponse characteristics of ZnO thin films deposited by three different techniques namely rf diode sputtering, rf magnetron sputtering, and electrophoretic deposition has been investigated in the metal-semiconductor-metal (MSM) configuration. A significant variation in the crystallinity, surface morphology, and photoresponse characteristics of ZnO thin film with change in growth kinetics suggest that the presence of defect centers and their density govern the photodetector relaxation properties. A relatively low density of traps compared to the true quantum yield is found very crucial for the realization of practical ZnO thin film based ultraviolet (UV) photodetector.

A comparative study of ultraviolet photoconductivity relaxation in zinc oxide (ZnO) thin films deposited by different techniques

Energy Technology Data Exchange (ETDEWEB)

Yadav, Harish Kumar; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110 007 (India)

2012-05-15

Photoresponse characteristics of ZnO thin films deposited by three different techniques namely rf diode sputtering, rf magnetron sputtering, and electrophoretic deposition has been investigated in the metal-semiconductor-metal (MSM) configuration. A significant variation in the crystallinity, surface morphology, and photoresponse characteristics of ZnO thin film with change in growth kinetics suggest that the presence of defect centers and their density govern the photodetector relaxation properties. A relatively low density of traps compared to the true quantum yield is found very crucial for the realization of practical ZnO thin film based ultraviolet (UV) photodetector.

Effect of Zn(NO{sub 3}){sub 2} concentration in hydrothermal–electrochemical deposition on morphology and photoelectrochemical properties of ZnO nanorods

Energy Technology Data Exchange (ETDEWEB)

Yilmaz, Ceren, E-mail: ceryilmaz@ku.edu.tr [Koc University, Department of Chemistry, Rumelifeneri yolu, Sariyer 34450, Istanbul (Turkey); Unal, Ugur [Koc University, Department of Chemistry, Rumelifeneri yolu, Sariyer 34450, Istanbul (Turkey); Graduate School of Science and Engineering, Koc University, Rumelifeneri yolu, Sariyer 34450, Istanbul (Turkey); Koc University Surface Science and Technology Center (KUYTAM), Rumelifeneri yolu, Sariyer 34450, Istanbul (Turkey)

2016-04-15

Graphical abstract: - Highlights: • Combined hydrothermal–electrochemical deposition was used to grow ZnO films. • 1-D ZnO NRs are obtained even at high Zn(NO{sub 3}){sub 2} concentrations (1 mM < [Zn{sup 2+}] < 0.1 M). • Aspect ratio and alignment of ZnO NRs can be controlled by initial [Zn(NO{sub 3}){sub 2}]. • [Zn{sup 2+}] dependent structural and photoelectrochemical properties have been studied. • Photocurrent density exhibited by ZnO NRs increases with increasing aspect ratio. - Abstract: Zn(NO{sub 3}){sub 2} concentration had been reported to be significantly influential on electrodeposition of ZnO structures. In this work, this issue is revisited using hydrothermal–electrochemical deposition (HED). Seedless, cathodic electrochemical deposition of ZnO films is carried out on ITO electrode at 130 °C in a closed glass reactor with varying Zn(NO{sub 3}){sub 2} concentration. Regardless of the concentration of Zn{sup 2+} precursor (0.001–0.1 M) in the deposition solution, vertically aligned 1-D ZnO nanorods are obtained as opposed to electrodepositions at lower temperatures (70–80 °C). We also report the effects of high bath temperature and pressure on the photoelectrochemical properties of the ZnO films. Manipulation of precursor concentration in the deposition solution allows adjustment of the aspect ratio of the nanorods and the degree of texturation along the c-axis; hence photoinduced current density. HED is shown to provide a single step synthesis route to prepare ZnO rods with desired aspect ratio specific for the desired application just by controlling the precursor concentration.

Effects of preannealing temperature of ZnO thin films on the performance of dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Kao, M.C.; Chen, H.Z.; Young, S.L. [Hsiuping Institute of Technology, Department of Electronic Engineering, Taichung (China)

2010-03-15

The preferred (002) orientation zinc oxide (ZnO) nanocrystalline thin films have been deposited on FTO-coated glass substrates by sol-gel spin-coating technology and rapid thermal annealing for use in dye-sensitized solar cells (DSSC). The effects of preannealing temperature (100 and 300 C) on the microstructure, morphology and optical properties of ZnO thin films were studied. The ZnO thin films were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM) and Brunauer-Emmett-Teller (BET) analysis. The photoelectric performance of DSSC was studied by I-V curve and the incident photon-to-current conversion efficiency (IPCE), respectively. From the results, the intensities of (002) peaks of ZnO thin films increases with increasing preannealing temperature from 100 C to 300 C. The increase in pore size and surface area of ZnO films crystallized at the increased preannealing temperature contributed to the improvement on the absorption of N3 dye onto the films, the short-circuit photocurrent (J{sub sc}) and open-circuit voltage (V{sub oc}) of DSSC. The higher efficiency ({eta}) of 2.5% with J{sub sc} and V{sub oc} of 8.2 mA/cm{sup 2} and 0.64 V, respectively, was obtained by the ZnO film preannealed at 300 C. (orig.)

Investigation on structural aspects of ZnO nano-crystal using radio-active ion beam and PAC

Energy Technology Data Exchange (ETDEWEB)

Ganguly, Bichitra Nandi, E-mail: bichitra.ganguly@saha.ac.in [Saha Institute of Nuclear Physics, Kolkata 700064 (India); Dutta, Sreetama; Roy, Soma [Saha Institute of Nuclear Physics, Kolkata 700064 (India); Röder, Jens [Physics Department, ISOLDE/CERN, Geneva (Switzerland); Physical Chemistry, RWTH-Aachen, Aachen (Germany); Johnston, Karl [Physics Department, ISOLDE/CERN, Geneva (Switzerland); Experimental Physics, University of the Saarland, Saarbrücken (Germany); Martin, Manfred [Physical Chemistry, RWTH-Aachen, Aachen (Germany)

2015-11-01

Nano-crystalline ZnO has been studied with perturbed angular correlation using {sup 111m}Cd, implanted at ISOLDE/CERN and X-ray diffraction using Rietveld analysis. The data show a gradual increase in the crystal size and stress for a sample annealed at 600 °C, and reaching nearly properties of standard ZnO with tempering at 1000 °C. The perturbed angular correlation data show a broad frequency distribution at low annealing temperatures and small particle sizes, whereas at high annealing temperature and larger crystal sizes, results similar to bulk ZnO have been obtained. The ZnO nano-crystalline samples were initially prepared through a wet chemical route, have been examined by Fourier Transform Infrared Spectroscopy (FT-IR) and chemical purity has been confirmed with Energy Dispersive X-ray (EDAX) analysis as well as Transmission Electron Microscopy (TEM).

Antibacterial and barrier properties of oriented polymer films with ZnO thin films applied with atomic layer deposition at low temperatures

International Nuclear Information System (INIS)

Vähä-Nissi, Mika; Pitkänen, Marja; Salo, Erkki; Kenttä, Eija; Tanskanen, Anne; Sajavaara, Timo; Putkonen, Matti; Sievänen, Jenni; Sneck, Asko; Rättö, Marjaana; Karppinen, Maarit; Harlin, Ali

2014-01-01

Concerns on food safety, and need for high quality and extended shelf-life of packaged foods have promoted the development of antibacterial barrier packaging materials. Few articles have been available dealing with the barrier or antimicrobial properties of zinc oxide thin films deposited at low temperature with atomic layer deposition (ALD) onto commercial polymer films typically used for packaging purposes. The purpose of this paper was to study the properties of ZnO thin films compared to those of aluminum oxide. It was also possible to deposit ZnO thin films onto oriented polylactic acid and polypropylene films at relatively low temperatures using ozone instead of water as an oxidizing precursor for diethylzinc. Replacing water with ozone changed both the structure and the chemical composition of films deposited on silicon wafers. ZnO films deposited with ozone contained large grains covered and separated probably by a more amorphous and uniform layer. These thin films were also assumed to contain zinc salts of carboxylic acids. The barrier properties of a 25 nm ZnO thin film deposited with ozone at 100 °C were quite close to those obtained earlier with ALD Al 2 O 3 of similar apparent thickness on similar polymer films. ZnO thin films deposited at low temperature indicated migration of antibacterial agent, while direct contact between ZnO and Al 2 O 3 thin films and bacteria promoted antibacterial activity. - Highlights: • Thin films were grown from diethylzinc also with ozone instead of water at 70 and 100 °C. • ZnO films deposited with diethylzinc and ozone had different structures and chemistries. • Best barrier properties obtained with zinc oxide films close to those obtained with Al 2 O 3 • Ozone as oxygen source provided better barrier properties at 100 °C than water. • Both aluminum and zinc oxide thin films showed antimicrobial activity against E. coli

Antibacterial and barrier properties of oriented polymer films with ZnO thin films applied with atomic layer deposition at low temperatures

Energy Technology Data Exchange (ETDEWEB)

Vähä-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Pitkänen, Marja; Salo, Erkki; Kenttä, Eija [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Tanskanen, Anne, E-mail: Anne.Tanskanen@aalto.fi [Aalto University, School of Chemical Technology, Department of Chemistry, Laboratory of Inorganic Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Sajavaara, Timo, E-mail: timo.sajavaara@jyu.fi [University of Jyväskylä, Department of Physics, P.O. Box 35, FI-40014 Jyväskylä (Finland); Putkonen, Matti; Sievänen, Jenni; Sneck, Asko; Rättö, Marjaana [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland); Karppinen, Maarit, E-mail: Maarit.Karppinen@aalto.fi [Aalto University, School of Chemical Technology, Department of Chemistry, Laboratory of Inorganic Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Harlin, Ali [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044, VTT (Finland)

2014-07-01

Concerns on food safety, and need for high quality and extended shelf-life of packaged foods have promoted the development of antibacterial barrier packaging materials. Few articles have been available dealing with the barrier or antimicrobial properties of zinc oxide thin films deposited at low temperature with atomic layer deposition (ALD) onto commercial polymer films typically used for packaging purposes. The purpose of this paper was to study the properties of ZnO thin films compared to those of aluminum oxide. It was also possible to deposit ZnO thin films onto oriented polylactic acid and polypropylene films at relatively low temperatures using ozone instead of water as an oxidizing precursor for diethylzinc. Replacing water with ozone changed both the structure and the chemical composition of films deposited on silicon wafers. ZnO films deposited with ozone contained large grains covered and separated probably by a more amorphous and uniform layer. These thin films were also assumed to contain zinc salts of carboxylic acids. The barrier properties of a 25 nm ZnO thin film deposited with ozone at 100 °C were quite close to those obtained earlier with ALD Al{sub 2}O{sub 3} of similar apparent thickness on similar polymer films. ZnO thin films deposited at low temperature indicated migration of antibacterial agent, while direct contact between ZnO and Al{sub 2}O{sub 3} thin films and bacteria promoted antibacterial activity. - Highlights: • Thin films were grown from diethylzinc also with ozone instead of water at 70 and 100 °C. • ZnO films deposited with diethylzinc and ozone had different structures and chemistries. • Best barrier properties obtained with zinc oxide films close to those obtained with Al{sub 2}O{sub 3} • Ozone as oxygen source provided better barrier properties at 100 °C than water. • Both aluminum and zinc oxide thin films showed antimicrobial activity against E. coli.

Synthesis of cadmium oxide doped ZnO nanostructures using electrochemical deposition

International Nuclear Information System (INIS)

Singh, Trilok; Pandya, D.K.; Singh, R.

2011-01-01

Research highlights: → Ternary ZnCdO alloy semiconductor nanostructures were grown using electrochemical deposition. → X-ray diffraction measurements showed that the nanostructures were of wurtzite structure and possessed a compressive stress along the c-axis direction. → The cut-off wavelength shifted from blue to red on account of the Cd incorporation in the ZnO and the average transmittance decreased by ∼31%. → The bandgap tuning for 4-16 at% Cd in the initial solution was achieved in the range of 3.08-3.32 eV (up to 0.24 eV). - Abstract: Ternary ZnCdO alloy semiconductor nanostructures were grown using electrochemical deposition. Crystalline nanostructures/nanorods with cadmium concentration ranging from 4 to 16 at% in the initial solution were electrodeposited on tin doped indium oxide (ITO) conducting glass substrates at a constant cathodic potential -0.9 V and subsequently annealed in air at 300 deg. C. X-ray diffraction measurements showed that the nanostructures were of wurtzite structure and possessed a compressive stress along the c-axis direction. The elemental composition of nanostructures was confirmed by energy dispersive spectroscopy (EDS). ZnO nanostructures were found to be highly transparent and had an average transmittance of 85% in the visible range of the spectrum. After the incorporation of Cd content into ZnO the average transmittance decreased and the bandgap tuning was also achieved.

Effect of atomic layer deposition temperature on the performance of top-down ZnO nanowire transistors

Science.gov (United States)

2014-01-01

This paper studies the effect of atomic layer deposition (ALD) temperature on the performance of top-down ZnO nanowire transistors. Electrical characteristics are presented for 10-μm ZnO nanowire field-effect transistors (FETs) and for deposition temperatures in the range 120°C to 210°C. Well-behaved transistor output characteristics are obtained for all deposition temperatures. It is shown that the maximum field-effect mobility occurs for an ALD temperature of 190°C. This maximum field-effect mobility corresponds with a maximum Hall effect bulk mobility and with a ZnO film that is stoichiometric. The optimized transistors have a field-effect mobility of 10 cm2/V.s, which is approximately ten times higher than can typically be achieved in thin-film amorphous silicon transistors. Furthermore, simulations indicate that the drain current and field-effect mobility extraction are limited by the contact resistance. When the effects of contact resistance are de-embedded, a field-effect mobility of 129 cm2/V.s is obtained. This excellent result demonstrates the promise of top-down ZnO nanowire technology for a wide variety of applications such as high-performance thin-film electronics, flexible electronics, and biosensing. PMID:25276107

ZnO film deposition by DC magnetron sputtering: Effect of target configuration on the film properties

Energy Technology Data Exchange (ETDEWEB)

Arakelova, E.; Khachatryan, A.; Kteyan, A.; Avjyan, K.; Grigoryan, S.

2016-08-01

Ballistic transport model for target-to-substrate atom transfer during magnetron sputter deposition was used to develop zinc target (cathode) configuration that enabled growth of uniform zinc oxide films on extensive surfaces and provided reproducibility of films characteristics irrespective of the cathode wear-out. The advantage of the developed target configuration for high-quality ZnO film deposition was observed in the sputtering pressure range of 5− 50 mTorr, and in the range of cathode-to-substrate distances 7–20 cm. Characteristics of the deposited films were demonstrated by using X-ray diffraction analysis, as well as optical and electrical measurements. - Highlights: • Change of target configuration for optimization of magnetron sputtering deposition is proposed. • Improvement of ZnO film properties due to use of this target is demonstrated. • This configuration provided reproducibility of the deposited films properties.

Atomic Layer Deposition of ZnO on Multi-walled Carbon Nanotubes and Its Use for Synthesis of CNT–ZnO Heterostructures

Directory of Open Access Journals (Sweden)

Li C

2010-01-01

Full Text Available Abstract In this article, direct coating of ZnO on PECVD-grown multi-walled carbon nanotubes (MWCNTs is achieved using atomic layer deposition (ALD. Transmission electron microscopy investigation shows that the deposited ZnO shell is continuous and uniform, in contrast to the previously reported particle morphology. The ZnO layer has a good crystalline quality as indicated by Raman and photoluminescence (PL measurements. We also show that such ZnO layer can be used as seed layer for subsequent hydrothermal growth of ZnO nanorods, resulting in branched CNT–inorganic hybrid nanostructures. Potentially, this method can also apply to the fabrication of ZnO-based hybrid nanostructures on other carbon nanomaterials.

Exploring the potential of laser assisted flow deposition grown ZnO for photovoltaic applications

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, J., E-mail: joana.catarina@ua.pt [Departamento de Física & I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Cerqueira, A.F.R.; Sousa, M.G.; Santos, N.F. [Departamento de Física & I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Pimentel, A.; Fortunato, E. [CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Cunha, A.F. da; Monteiro, T.; Costa, F.M. [Departamento de Física & I3N, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal)

2016-07-01

Zinc oxide (ZnO) is a widely studied wide band gap semiconductor with applications in several fields, namely to enhance solar cells efficiency. Its ability to be grown in a wide variety of nanostructured morphologies, allowing the designing of the surface area architecture constitutes an important advantage over other semiconductors. Laser assisted flow deposition (LAFD) is a recently developed growth method, based on a vapour-solid mechanism, which proved to be a powerful approach in the production of ZnO micro/nanostructures with different morphologies as well as high crystallinity and optical quality. In the present work we report the use of the LAFD technique to grow functional ZnO nanostructures (nanoparticles and tetrapods) working as nano templates to improve the dye-sensitized solar cells (DSSCs) efficiency. The structural and morphological characterization of the as-grown ZnO crystals were performed by X-ray diffraction and electron microscopy, respectively, and the optical quality was assessed by photoluminescence spectroscopy. DSSCs were produced using a combination of these nanostructures, which were subsequently sensitized with N719 dye. An efficiency of ∼3% was achieved under simulated AM 1.5 illumination conditions for a dye loading time of 1 h. - Highlights: • Laser assisted flow deposition proved to be an efficient technique to produce high quality ZnO. • Active layer formed by an interconnected network of tetrapods and a small amount of nanoparticles. • Efficiency of ∼3% obtained under simulated AM 1.5 illumination conditions.

Optoelectronic Characterization of Ta-Doped ZnO Thin Films by Pulsed Laser Deposition.

Science.gov (United States)

Koo, Horng-Show; Peng, Jo-Chi; Chen, Mi; Chin, Hung-I; Chen, Jaw-Yeh; Wu, Maw-Kuen

2015-11-01

Transparent conductive oxide of Ta-doped ZnO (TZO) film with doping amount of 3.0 wt% have been deposited on glass substrates (Corning Eagle XG) at substrate temperatures of 100 to 500 degrees C by the pulsed laser deposition (PLD) technique. The effect of substrate temperature on the structural, optical and electronic characteristics of Ta-doped ZnO (TZO) films with 3.0 wt% dopant of tantalum oxide (Ta2O5) was measured and demonstrated in terms of X-ray diffraction (XRD), ultraviolet-visible spectrometer (UV-Vis), four-probe and Hall-effect measurements. X-ray diffraction pattern shows that TZO films grow in hexagonal crystal structure of wurtzite phase with a preferred orientation of the crystallites along (002) direction and exhibits better physical characteristics of optical transmittance, electrical conductivity, carrier concentration and mobility for the application of window layer in the optoelectronic devices of solar cells, OLEDs and LEDs. The lowest electrical resistivity (ρ) and the highest carrier concentration of the as-deposited film deposited at 300 degrees C are measured as 2.6 x 10(-3) Ω-cm and 3.87 x 10(-20) cm(-3), respectively. The highest optical transmittance of the as-deposited film deposited at 500 degrees C is shown to be 93%, compared with another films deposited below 300 degrees C. It is found that electrical and optical properties of the as-deposited TZO film are greatly dependent on substrate temperature during laser ablation deposition.

Nanocrystalline transparent SnO{sub 2}-ZnO films fabricated at lower substrate temperature using a low-cost and simplified spray technique

Energy Technology Data Exchange (ETDEWEB)

Ravichandran, K.; Sakthivel, B.; Philominathan, P. [P. G. and Research Department of Physics, AVVM. Sri Pushpam College, Poondi, Thanjavur, Tamilnadu 613503 (India)

2010-03-15

Nanocrystalline and transparent conducting SnO{sub 2}- ZnO films were fabricated by employing an inexpensive, simplified spray technique using a perfume atomizer at relatively low substrate temperature (360{+-}5 C) compared with conventional spray method. The structural studies reveal that the SnO{sub 2}-ZnO films are polycrystalline in nature with preferential orientation along the (101) plane. The dislocation density is very low (1.48 x 10{sup 15}lines/m{sup 2}), indicating the good crystallinity of the films. The crystallite size of the films was found to be in the range of 26-34 nm. The optical transmittance in the visible range and the optical band gap are 85% and 3.6 eV respectively. The sheet resistance increases from 8.74 k{omega}/{open_square} to 32.4 k{omega}/{open_square} as the zinc concentration increases from 0 to 40 at.%. The films were found to have desirable figure of merit (1.63 x 10{sup -2} ({omega}/{open_square}){sup -1}), low temperature coefficient of resistance (-1.191/K) and good thermal stability. This simplified spray technique may be considered as a promising alternative to conventional spray for the massive production of economic SnO{sub 2} - ZnO films for solar cells, sensors and opto-electronic applications. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Obtaining ZnO nanocrystalline through methods of combustion and precipitation

International Nuclear Information System (INIS)

Garcia, A.P.; Guaglianoni, W.C.; Cunha, M.A.; Basegio, T.M.; Bergmann, C.P.

2012-01-01

Zinc oxide is important technological applications in rubber and industrial paints. The chemical properties and microstructure of ZnO powder depends on the synthesis method employed. In this work, it was obtained nanosized ZnO using different synthesis processes, such as solution combustion and precipitation, varying the concentrations of reactants and the working temperature. The obtained powders were characterized by SEM, BET, XRD, crystallite size determination and thermal analysis (TGA and DTA). It was possible to obtain nanosized ZnO with the methods used. (author)

DFT calculations on electronic properties of ZnO thin films deposited by spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Cordeiro, J.M.; Reynoso, V.C.; Azevedo, D.H.M. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil)

2016-07-01

Full text: Introduction - Thin films of Zinc oxide (ZnO) has a wide range of technological applications, as transparent conducting electrodes in solar cells, flat panel displays, and sensors, for example. More recently applications in optoelectronics, like light emitter diodes and laser diodes, due to its large band gap, are been explored. Studies of ZnO thin films are important for these applications. Methodology - In this study thin films of ZnO have been deposited by spray pyrolysis on glass substrate. The films were characterized by XRD and UV-VIS techniques and the electronic properties as a function of the film thickness have been investigated by DFT calculations with B3LYP hybrid potential implemented in the CRYSTAL09 code. Results - The diffractograms obtained for the ZnO thin films as a function of the thickness are shown. The films exhibit a hexagonal wurtzite structure with preferred c-axis orientation in (002) direction of ZnO crystal. A quantum mechanical approach based on the periodic Density Functional Theory (DFT), with B3LYP hybrid potential was used to investigate the electronic structure of the films as a function of the thickness. The CRYSTAL09 code has been used for the calculations on the wurtzite hexagonal structure of ZnO - spatial group P63mc. For optimizing the geometry of the pure ZnO crystal, the experimental lattice parameters were got as follows: a= 0.325 nm, b= 0.325 nm, c= 0.5207 nm with c/a= 1.602. Considering to the calculations of the band structure, it is suggested that the semiconducting properties of ZnO arises from the overlapping of the 4s orbital of the conducting band of Zn and the 2p orbital of the top of valence band of O. Conclusions - The structure of ZnO thin film deposited on glass substrate present preferential orientation in (002) direction. Variation in the optical properties as a function of the film thickness was observed. The band gap energy was determined from optical analysis to be ∼ 3.27 eV. The refractive

Thermally and optically stimulated luminescence of new ZnO nano phosphors exposed to beta radiation

International Nuclear Information System (INIS)

Cruz V, C.; Burruel I, S.E.; Grijalva M, H.; Chernov, V.; Bernal, R.

2006-01-01

In this work, we report the thermoluminescence (TL) and the optically stimulated luminescence (OSL) of ZnO nano phosphors obtained by thermal annealing of ZnS powders synthesized by precipitation in a chemical bath deposition reaction. To obtain nanocrystalline ZnO, ZnS pellet-shaped samples were subjected to a sintering process at 700 C during 24 under air atmosphere. Some samples were exposed to beta particles in the 0.15-10.15 kGy dose range and the integrated thermoluminescence as a function of dose increased as dose increased, with no saturation clue for the tested doses. Computerized glow-curve deconvolution of the experimental TL curves in individual peaks revealed a second order kinetics. In order to test the BOSL (Blue Optically Stimulated Luminescence) response, samples were beta irradiated with doses up to 600 Gy, showing an increasing OSL intensity as dose increases. From the experimental results that we have obtained, we conclude that the new ZnO phosphors under investigation are good candidates to be used as dosimetric materials. (Author)

Electrophoretic deposition of nanocrystalline TiO2 films on Ti substrates for use in flexible dye-sensitized solar cells

International Nuclear Information System (INIS)

Tan Weiwei; Yin Xiong; Zhou Xiaowen; Zhang Jingbo; Xiao Xurui; Lin Yuan

2009-01-01

Nanocrystalline TiO 2 films were prepared on flexible Ti-metal sheets by electrophoretic deposition followed by chemical treatment with tetra-n-butyl titanate (TBT) and sintering at 450 deg. C. X-ray diffraction (XRD) analysis indicates that TBT treatment led to the formation of additional anatase TiO 2 , which plays an important role in improving the interconnection between TiO 2 particles, as well as the adherence of the film to the substrate, and in modifying the surface properties of the nanocrystalline particles. The effect of TBT treatment on the electron transport in the nanocrystalline films was studied by intensity-modulated photocurrent spectroscopy (IMPS). An increase in the conversion efficiency was obtained for the dye-sensitized solar cells with TBT-treated nanocrystalline TiO 2 films. The cell performance was further optimized by designing nanocrystalline TiO 2 films with a double-layer structure composed of a light-scattering layer and a transparent layer. The light-scattering effect of the double-layer nanocrystalline films was evaluated by diffuse reflectance spectra. Employing the double-layer nanocrystalline films as the photoelectrodes resulted in a significant improvement in the incident photo-to-current conversion efficiency of the corresponding cells due to enhanced solar absorption by light scattering. A high conversion efficiency of 6.33% was measured under illumination with 100 mW cm -2 (AM 1.5) simulated sunlight.

Increased charge storage capacity of titanium nitride electrodes by deposition of boron-doped nanocrystalline diamond films

DEFF Research Database (Denmark)

Meijs, Suzan; McDonald, Matthew; Sørensen, Søren

2015-01-01

The aim of this study was to investigate the feasibility of depositing a thin layer of boron-doped nanocrystalline diamond (B-NCD) on titanium nitride (TiN) coated electrodes and the effect this has on charge injection properties. The charge storage capacity increased by applying the B-NCD film...

Electrodeposition of ZnO nano-wires lattices with a controlled morphology

International Nuclear Information System (INIS)

Elias, J.; Tena-Zaera, R.; Katty, A.; Levy-Clement, C.

2006-01-01

In this work, it is shown that the electrodeposition is a changeable low cost method which allows, according to the synthesis conditions, to obtain not only plane thin layers of ZnO but different nano-structures too. In a first part, are presented the formation conditions of a compact thin layer of nanocrystalline ZnO electrodeposited on a conducing glass substrate. This layer plays a buffer layer role for the deposition of a lattice of ZnO nano-wires. The step of nano-wires nucleation is not only determined by the electrochemical parameters but by the properties of the buffer layer too as the grain sizes and its thickness. In this context, the use of an electrodeposition method in two steps allows to control the nano-wires length and diameter and their density. The morphology and the structural and optical properties of these nano-structures have been analyzed by different techniques as the scanning and transmission electron microscopy, the X-ray diffraction and the optical spectroscopy. These studies show that ZnO nano-structures are formed of monocrystalline ZnO nano-wires, presenting a great developed surface and a great optical transparency in the visible. These properties make ZnO a good material for the development of nano-structured photovoltaic cells as the extremely thin absorber cells (PV ETA) or those with dye (DSSC) which are generally prepared with porous polycrystalline TiO 2 . Its replacement by a lattice of monocrystalline ZnO nano-wires allows to reduce considerably the number of grain boundaries and in consequence to improve the transport of the electrons. The results are then promising for the PV ETA cells with ZnO nano-wires. (O.M.)

Characterization of n and p-type ZnO thin films grown by pulsed filtered cathodic vacuum arc system

International Nuclear Information System (INIS)

Kavak, H.; Erdogan, E.N.; Ozsahin, I.; Esen, R.

2010-01-01

Full text : Semiconductor ZnO thin films with wide band gap attract much interest due to their properties such as chemical stability in hydrogen plasma, high optical transparency in the visible and nearinfrared region. Due to these properties ZnO oxide is a promising materials for electronic or optoelectronic applications such as solar cell (as an antireflecting coating and a transparent conducting material), gas sensors, surface acoustic wave devices. The purpose of this research is to improve the properties of n and p-type ZnO thin films for device applications. Polycrystalline ZnO is naturally n-type and very difficult to dope to make p-type. Therefore nowadays hardly produced p-type ZnO attracts a lot of attention. Nitrogen considered as the best dopant for p-type ZnO thin films.The transparent, conductive and very precise thickness controlled n and p-type semiconducting nanocrystalline ZnO thin films were prepared by pulsed filtered cathodic vacuum arc deposition (PFCVAD) method. Structural, optical and electrical properties of these films were investigated. And also photoluminescence properties of these films were investigated. Transparent p-type ZnO thin films were produced by oxidation of PFCVAD deposited zinc nitride. Zinc nitride thin films were deposited with various thicknesses and under different oxygen pressures on glass substrates. Zinc nitride thin films, which were deposited at room temperatures, were amorphous and the optical transmission was below 70%. For oxidation zinc nitride, the sample was annealed in air starting from 350 degrees Celsium up to 550 degrees Celsium for one hour duration. These XRD patterns imply that zinc nitride thin films converted to zinc oxide thin films with the same hexagonal crystalline structures of ZnO. The optical measurements were made for each annealing temperature and the optical transmissions of ZnO thin films were found better than 90 percent in visible range after annealing over 350 degrees Celsium. By

Biofunctionalization of carbon nanotubes/chitosan hybrids on Ti implants by atom layer deposited ZnO nanostructures

Energy Technology Data Exchange (ETDEWEB)

Zhu, Yizhou; Liu, Xiangmei [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei Key Laboratory of Polymer Materials, School of Materials Science & Engineering, Hubei University, Wuhan 430062 (China); Yeung, Kelvin W.K. [Division of Spine Surgery, Department of Orthopaedics & Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong (China); Chu, Paul K. [Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Wu, Shuilin, E-mail: shuilin.wu@gmail.com [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei Key Laboratory of Polymer Materials, School of Materials Science & Engineering, Hubei University, Wuhan 430062 (China)

2017-04-01

Highlights: • Carbon naonotubes/chitosan/ZnO coating was first constructed on Ti implants. • This system endowed Ti implants with excellent self-antibacterial activity. • The amount of Zn could be precisely controlled by atom layer deposition. • This system could regulate cell behaviors on metallic implants. - Abstract: One-dimensional (1D) nanostructures of ZnO using atomic layer deposition (ALD) on chitosan (CS) modified carbon nanotubes (CNTs) were first introduced onto the surfaces of biomedical implants. When the content of ZnO is not sufficient, CNTs can strengthen the antibacterial activity against E. coli and S. aureus by 8% and 39%, respectively. CS can improve the cytocompatibility of CNTs and ZnO. The amount of Zn content can be controlled by changing the cycling numbers of ALD processes. This hybrid coating can not only endow medical implants with high self-antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of over 73% and 98%, respectively, but also regulate the proliferation and osteogenic differentiation of osteoblasts by controlling the amount of ZnO.

Biofunctionalization of carbon nanotubes/chitosan hybrids on Ti implants by atom layer deposited ZnO nanostructures

International Nuclear Information System (INIS)

Zhu, Yizhou; Liu, Xiangmei; Yeung, Kelvin W.K.; Chu, Paul K.; Wu, Shuilin

2017-01-01

Highlights: • Carbon naonotubes/chitosan/ZnO coating was first constructed on Ti implants. • This system endowed Ti implants with excellent self-antibacterial activity. • The amount of Zn could be precisely controlled by atom layer deposition. • This system could regulate cell behaviors on metallic implants. - Abstract: One-dimensional (1D) nanostructures of ZnO using atomic layer deposition (ALD) on chitosan (CS) modified carbon nanotubes (CNTs) were first introduced onto the surfaces of biomedical implants. When the content of ZnO is not sufficient, CNTs can strengthen the antibacterial activity against E. coli and S. aureus by 8% and 39%, respectively. CS can improve the cytocompatibility of CNTs and ZnO. The amount of Zn content can be controlled by changing the cycling numbers of ALD processes. This hybrid coating can not only endow medical implants with high self-antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) of over 73% and 98%, respectively, but also regulate the proliferation and osteogenic differentiation of osteoblasts by controlling the amount of ZnO.

Preparation of nanocrystalline ZnS by a new chemical bath deposition route

Energy Technology Data Exchange (ETDEWEB)

Sartale, S.D. [Department of Heterogeneous Material Systems (SE2), Hahn-Meitner-Institut, Glienicker Strasse 100, D-14109, Berlin (Germany); Sankapal, B.R. [Department of Heterogeneous Material Systems (SE2), Hahn-Meitner-Institut, Glienicker Strasse 100, D-14109, Berlin (Germany); Lux-Steiner, M. [Department of Heterogeneous Material Systems (SE2), Hahn-Meitner-Institut, Glienicker Strasse 100, D-14109, Berlin (Germany); Ennaoui, A. [Department of Heterogeneous Material Systems (SE2), Hahn-Meitner-Institut, Glienicker Strasse 100, D-14109, Berlin (Germany)]. E-mail: ennaoui@hmi.de

2005-06-01

We report a new chemical bath deposition route for the preparation of dense, compact and uniform nanocrystalline ZnS thin films, where thiourea acts as a complexing agent as well as a source of sulfide ions. The structural and morphological characterizations suggest that the film and the residual powder in the bath are formed by the aggregation of clusters of ZnS, namely cluster-by-cluster growth mechanism. X-ray diffraction (XRD) and HRTEM analyses indicate that the film and powder formed in the bath have cubic zinkblende structure. The films have high transmittance of about 75% in the visible region. Post-deposition annealing in Ar slightly improves the crystallinity and decreases the optical bandgap with increasing the annealing temperature.

Preparation of nanocrystalline ZnS by a new chemical bath deposition route

International Nuclear Information System (INIS)

Sartale, S.D.; Sankapal, B.R.; Lux-Steiner, M.; Ennaoui, A.

2005-01-01

We report a new chemical bath deposition route for the preparation of dense, compact and uniform nanocrystalline ZnS thin films, where thiourea acts as a complexing agent as well as a source of sulfide ions. The structural and morphological characterizations suggest that the film and the residual powder in the bath are formed by the aggregation of clusters of ZnS, namely cluster-by-cluster growth mechanism. X-ray diffraction (XRD) and HRTEM analyses indicate that the film and powder formed in the bath have cubic zinkblende structure. The films have high transmittance of about 75% in the visible region. Post-deposition annealing in Ar slightly improves the crystallinity and decreases the optical bandgap with increasing the annealing temperature

Detailed microstructure analysis of as-deposited and etched porous ZnO films

International Nuclear Information System (INIS)

Shang, Congcong; Thimont, Yohann; Barnabé, Antoine; Presmanes, Lionel; Pasquet, Isabelle; Tailhades, Philippe

2015-01-01

Graphical abstract: - Highlights: • Porous ZnO thin films were deposited by rf magnetron sputtering. • Surface enhancement factors were deduced from geometrical considerations. • Enlargement of the inter-grain spaces have been achieved by HCl chemical etching. • Microstructural parameters were deduced from SEM, AFM and optical measurements. - Abstract: ZnO nanostructured materials in thin film forms are of particular interest for photovoltaic or photocatalysis processes but they suffer from a lack of simple methods for optimizing their microstructure. We have demonstrated that microporous ZnO thin films with optimized inter grain accessibility can be produce by radio frequency magnetron sputtering process and chemical etching with 2.75 mM HCl solution for different duration. The as-deposited ZnO thin films were first characterized in terms of structure, grain size, inter grain space, open cavity depth and total thickness of the film by XRD, AFM, SEM, profilometry and optical measurements. A specific attention was dedicated to the determination of the surface enhancement factor (SEF) by using basic geometrical considerations and images treatments. In addition, the porous fraction and its distribution in the thickness have been estimated thanks to the optical simulation of the experimental UV–Visible–IR spectrums using the Bruggeman dielectric model and cross section SEM images analysis respectively. This study showed that the microstructure of the as-deposited films consists of a dense layer covered by a porous upper layer developing a SEF of 12–13 m 2 m −2 . This two layers architecture is not modified by the etching process. The etching process only affects the upper porous layer in which the overall porosity and the inter-grain space increase with the etching duration. Column diameter and total film thickness decrease at the same time when the films are soaked in the HCl bath. The microporous structure obtained after the etching process could

Properties of In–N codoped p-type ZnO nanorods grown through a two-step chemical route

Energy Technology Data Exchange (ETDEWEB)

Duta, M.; Mihaiu, S.; Munteanu, C. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Anastasescu, M., E-mail: manastasescu@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Osiceanu, P.; Marin, A.; Preda, S. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Nicolescu, M., E-mail: mnicolescu2006@yahoo.com [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania); Modreanu, M. [Tyndall National Institute, University College, Cork (Ireland); Zaharescu, M.; Gartner, M. [Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest (Romania)

2015-07-30

Highlights: • p-Type ZnO film codoped with In, N on glass substrate was obtained. • The films were prepared by sol–gel followed by hydrothermal method. • Influence of annealing regimes on opto-electrical properties was studied. • Thin films morphology consists of interconnected, randomly oriented nanorods. • 3.31 × 10{sup 17} cm{sup −3}carrier concentration and 85% transmission were obtained at 500 °C. - Abstract: By codoping with a donor–acceptor pair through a two-step chemical method we have succeed to obtain p-type ZnO thin films on glass. Firstly, a thin undoped ZnO seed layer was deposited by sol–gel method followed by the deposition of In–N codoped ZnO film obtained through the hydrothermal technique. The influence of post-deposition annealing temperature (100 °C, 300 °C and 500 °C) on the samples was investigated from a structural, chemical, morphological and optoelectrical point of view. X-ray diffractometry (XRD), infrared ellipsometry and X-ray photoelectron spectroscopy (XPS) analyses have confirmed the codoped nature of the ZnO thin films. The XRD pattern analysis has established the films have wurtzite nanocrystalline structure, the crystallite sizes varying between 10 nm and 13 nm with the annealing temperature. Continuous and homogenous films with nanorods surface morphology has been obtained, as visualized by scanning electron microscopy measurements. Hall Effect measurements have established that all samples, regardless of annealing temperature, showed p-type conduction due to the successful incorporation of nitrogen in the film, with the highest carrier concentration registered at 500 °C. This is in good correlation with the nitrogen content in the films as revealed from XPS. In all samples, the XPS depth profiling has shown a nitrogen gradient with higher elemental concentration at the surface.

Photocatalytic efficiency of reusable ZnO thin films deposited by sputtering technique

International Nuclear Information System (INIS)

Ahumada-Lazo, R.; Torres-Martínez, L.M.; Ruíz-Gómez, M.A.; Vega-Becerra, O.E.

2014-01-01

Graphical abstract: - Highlights: • Decolorization of Orange G dye using highly c-axis-oriented ZnO thin films. • The flake-shaped film shows superior and stable photoactivity at a wide range of pH. • The highest photodecolorization was achieved at pH of 7. • The exposure of (101) and (100) facets enhanced the photoactivity. • ZnO thin films exhibit a promising performance as recyclable photocatalysts. - Abstract: The photocatalytic activity of ZnO thin films with different physicochemical characteristics deposited by RF magnetron sputtering on glass substrate was tested for the decolorization of orange G dye aqueous solution (OG). The crystalline phase, surface morphology, surface roughness and the optical properties of these ZnO films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV–visible spectroscopy (UV–Vis), respectively. The dye photodecolorization process was studied at acid, neutral and basic pH media under UV irradiation of 365 nm. Results showed that ZnO films grow with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a (002) preferential crystalline orientation. A clear relationship between surface morphology and photocatalytic activity was observed for ZnO films. Additionally, the recycling photocatalytic abilities of the films were also evaluated. A promising photocatalytic performance has been found with a very low variation of the decolorization degree after five consecutive cycles at a wide range of pH media

Photocatalytic efficiency of reusable ZnO thin films deposited by sputtering technique

Energy Technology Data Exchange (ETDEWEB)

Ahumada-Lazo, R.; Torres-Martínez, L.M. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450, México (Mexico); Ruíz-Gómez, M.A. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Civil, Departamento de Ecomateriales y Energía, Av. Universidad S/N Ciudad Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450, México (Mexico); Departmento de Física Aplicada, CINVESTAV-IPN, Antigua Carretera a Progreso km 6, Mérida, Yucatán 97310, México (Mexico); Vega-Becerra, O.E. [Centro de Investigación en Materiales Avanzados S.C, Alianza norte 202, Parque de Investigación e Innovación Tecnológica, C.P. 66600 Apodaca Nuevo León, México (Mexico); and others

2014-12-15

Graphical abstract: - Highlights: • Decolorization of Orange G dye using highly c-axis-oriented ZnO thin films. • The flake-shaped film shows superior and stable photoactivity at a wide range of pH. • The highest photodecolorization was achieved at pH of 7. • The exposure of (101) and (100) facets enhanced the photoactivity. • ZnO thin films exhibit a promising performance as recyclable photocatalysts. - Abstract: The photocatalytic activity of ZnO thin films with different physicochemical characteristics deposited by RF magnetron sputtering on glass substrate was tested for the decolorization of orange G dye aqueous solution (OG). The crystalline phase, surface morphology, surface roughness and the optical properties of these ZnO films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV–visible spectroscopy (UV–Vis), respectively. The dye photodecolorization process was studied at acid, neutral and basic pH media under UV irradiation of 365 nm. Results showed that ZnO films grow with an orientation along the c-axis of the substrate and exhibit a wurtzite crystal structure with a (002) preferential crystalline orientation. A clear relationship between surface morphology and photocatalytic activity was observed for ZnO films. Additionally, the recycling photocatalytic abilities of the films were also evaluated. A promising photocatalytic performance has been found with a very low variation of the decolorization degree after five consecutive cycles at a wide range of pH media.

Electrochemical and hydrothermal deposition of ZnO on silicon: from continuous films to nanocrystals

International Nuclear Information System (INIS)

Balucani, M.; Nenzi, P.; Chubenko, E.; Klyshko, A.; Bondarenko, V.

2011-01-01

This article presents the study of the electrochemical deposition of zinc oxide from the non-aqueous solution based on dimethyl sulfoxide and zinc chloride into the porous silicon matrix. The features of the deposition process depending on the thickness of the porous silicon layer are presented. It is shown that after deposition process the porous silicon matrix is filled with zinc oxide nanocrystals with a diameter of 10–50 nm. The electrochemically deposited zinc oxide layers on top of porous silicon are shown to have a crystalline structure. It is also shown that zinc oxide crystals formed by hydrothermal method on the surface of electrochemically deposited zinc oxide film demonstrate ultra-violet luminescence. The effect of the porous silicon layer thickness on the morphology of the zinc oxide is shown. The structures obtained demonstrated two luminescence bands peaking at the 375 and 600 nm wavelengths. Possible applications of ZnO nanostructures, porous and continuous polycrystalline ZnO films such as gas sensors, light-emitting diodes, photovoltaic devices, and nanopiezo energy generators are considered. Aspects of integration with conventional silicon technology are also discussed.

Propeller-Shaped ZnO Nano structures Obtained by Chemical Vapor Deposition: Photoluminescence and Photo catalytic Properties

International Nuclear Information System (INIS)

Wang, S.L.; Zhu, H.W.; Li, P.G.; Tang, W.H.

2012-01-01

Propeller-shaped and flower-shaped ZnO nano structures on Si substrates were prepared by a one-step chemical vapor deposition technique. The propeller-shaped ZnO nano structure consists of a set of axial nano rod (50 nm in tip, 80 nm in root and 1μm in length), surrounded by radial-oriented nano ribbons (20-30 nm in thickness and 1.5μm in length). The morphology of flower-shaped ZnO nano structure is similar to that of propeller-shaped ZnO, except the shape of leaves. These nano rods leaves (30?nm in diameter and 1-1.5μm in length) are aligned in a radial way and pointed toward a common center. The flower-shaped ZnO nano structures show sharper and stronger UV emission at 378 nm than the propeller-shaped ZnO, indicating a better crystal quality and fewer structural defects in flower-shaped ZnO. In comparison with flower-shaped ZnO nano structures, the propeller-shaped ZnO nano structures exhibited a higher photo catalytic property for the photo catalytic degradation of Rhodamine B under UV-light illumination.

Nano-Crystalline Diamond Films with Pineapple-Like Morphology Grown by the DC Arcjet vapor Deposition Method

Science.gov (United States)

Li, Bin; Zhang, Qin-Jian; Shi, Yan-Chao; Li, Jia-Jun; Li, Hong; Lu, Fan-Xiu; Chen, Guang-Chao

2014-08-01

A nano-crystlline diamond film is grown by the dc arcjet chemical vapor deposition method. The film is characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and Raman spectra, respectively. The nanocrystalline grains are averagely with 80 nm in the size measured by XRD, and further proven by Raman and HRTEM. The observed novel morphology of the growth surface, pineapple-like morphology, is constructed by cubo-octahedral growth zones with a smooth faceted top surface and coarse side surfaces. The as-grown film possesses (100) dominant surface containing a little amorphous sp2 component, which is far different from the nano-crystalline film with the usual cauliflower-like morphology.

Characterizations of multilayer ZnO thin films deposited by sol-gel spin coating technique

Directory of Open Access Journals (Sweden)

M.I. Khan

Full Text Available In this work, zinc oxide (ZnO multilayer thin films are deposited on glass substrate using sol-gel spin coating technique and the effect of these multilayer films on optical, electrical and structural properties are investigated. It is observed that these multilayer films have great impact on the properties of ZnO. X-ray Diffraction (XRD confirms that ZnO has hexagonal wurtzite structure. Scanning Electron Microscopy (SEM showed the crack-free films which have uniformly distributed grains structures. Both micro and nano particles of ZnO are present on thin films. Four point probe measured the electrical properties showed the decreasing trend between the average resistivity and the number of layers. The optical absorption spectra measured using UV–Vis. showed the average transmittance in the visible region of all films is 80% which is good for solar spectra. The performance of the multilayer as transparent conducting material is better than the single layer of ZnO. This work provides a low cost, environment friendly and well abandoned material for solar cells applications. Keywords: Multilayer films, Semiconductor, ZnO, XRD, SEM, Optoelectronic properties

Effect of the substrate surface topology and temperature on the structural properties of ZnO layers obtained by plasma enhanced chemical vapour deposition

Energy Technology Data Exchange (ETDEWEB)

Kitova, S; Danev, G, E-mail: skitova@clf.bas.b [Acad. J .Malinowski Central Laboratory of Photoprocesses, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.109, 1113 Sofia (Bulgaria)

2010-04-01

In this work thin ZnO layers were grown by metal-organic PECVD (RF 13.56 MHz) on Si wafers. Zn acetylacetonate was used as a precursor and oxygen as oxidant. A system for dosed injection of the precursor and oxidant into the plasma reactor was developed. The influence of the substrate surface topology and temperature on the structural properties of the deposited layers was studied. ZnO and graphite powder dispersions were used to modify the silicon wafers before starting the deposition process of the layers. Some of the ZnO layers were deposited on the back, unpolished, side of Si wafers. Depositions at 400 {sup 0}C were performed to examine the effect of the substrate temperatures on the layer growth. The film structure was examined by XRD and SEM. The results show that all layers are crystalline with hexagonal wurtzite structure. The crystallites are preferentially oriented along the c-axis direction perpendicular to the substrate surfaces. ZnO layers deposited on thin ZnO seed films and clean Si surface exhibit well-developed grain structures and more c-axis preferred phase with better crystal quality than that of the layers deposited on graphite seed layer or rough, unpolished Si wafer.

Polystyrene sphere monolayer assisted electrochemical deposition of ZnO nanorods with controlable surface density

Energy Technology Data Exchange (ETDEWEB)

Ramirez, D., E-mail: daniel.ramirez@ucv.c [Laboratorio de Electroquimica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Gomez, H. [Laboratorio de Electroquimica, Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Lincot, D. [Institute de Recherche et Developpement sur l' Energie Photovoltaique-IRDEP, 6 Quai Watier 78401, Chatou Cedex (France)

2010-02-15

In this paper we report the zinc oxide nanorods (ZnO NRs) growth by electrochemical deposition onto polycrystalline gold electrodes modified with assemblies of polystyrene sphere monolayers (PSSMs). Growth occurs through the interstitial spaces between the hexagonally close packed spheres. ZnO NRs nucleate in the region where three adjacent spheres leave a space, being able to grow and projected over the PSSMs. The nanorod surface density (N{sub NR}) shows a linear dependence with respect to a PS sphere diameter selected. XRD analysis shows these ZnO NRs are highly oriented along the (0 0 2) plane (c-axis). This open the possibility to have electronic devices with mechanically supported nanometric materials.

Characterization of ZnO film grown on polycarbonate by atomic layer deposition at low temperature

Energy Technology Data Exchange (ETDEWEB)

Lee, Gyeong Beom; Han, Gwon Deok; Shim, Joon Hyung; Choi, Byoung-Ho, E-mail: bhchoi@korea.ac.kr [School of Mechanical Engineering, Korea University, Seoul 136-707 (Korea, Republic of)

2015-01-15

ZnO is an attractive material for use in various technological products such as phosphors, gas sensors, and transparent conductors. Recently, aluminum-doped zinc oxide has received attention as a potential replacement for indium tin oxide, which is one of the transparent conductive oxides used in flat panel displays, organic light-emitting diodes, and organic solar cells. In this study, the characteristics of ZnO films deposited on polycarbonate (PC) substrates by atomic layer deposition (ALD) are investigated for various process temperatures. The growth mechanism of these films was investigated at low process temperatures using x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). XRD and XPS were used to determine the preferred orientation and chemical composition of the films, respectively. Furthermore, the difference of the deposition mechanisms on an amorphous organic material, i.e., PC substrate and an inorganic material such as silicon was discussed from the viewpoint of the diffusion and deposition of precursors. The structure of the films was also investigated by chemical analysis in order to determine the effect of growth temperature on the films deposited by ALD.

Carbon-coated ZnO mat passivation by atomic-layer-deposited HfO2 as an anode material for lithium-ion batteries.

Science.gov (United States)

Jung, Mi-Hee

2017-11-01

ZnO has had little consideration as an anode material in lithium-ion batteries compared with other transition-metal oxides due to its inherent poor electrical conductivity and large volume expansion upon cycling and pulverization of ZnO-based electrodes. A logical design and facile synthesis of ZnO with well-controlled particle sizes and a specific morphology is essential to improving the performance of ZnO in lithium-ion batteries. In this paper, a simple approach is reported that uses a cation surfactant and a chelating agent to synthesize three-dimensional hierarchical nanostructured carbon-coated ZnO mats, in which the ZnO mats are composed of stacked individual ZnO nanowires and form well-defined nanoporous structures with high surface areas. In order to improve the performance of lithium-ion batteries, HfO 2 is deposited on the carbon-coated ZnO mat electrode via atomic layer deposition. Lithium-ion battery devices based on the carbon-coated ZnO mat passivation by atomic layer deposited HfO 2 exhibit an excellent initial discharge and charge capacities of 2684.01 and 963.21mAhg -1 , respectively, at a current density of 100mAg -1 in the voltage range of 0.01-3V. They also exhibit cycle stability after 125 cycles with a capacity of 740mAhg -1 and a remarkable rate capability. Copyright © 2017 Elsevier Inc. All rights reserved.

Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition

Directory of Open Access Journals (Sweden)

Adib Abou Chaaya

2013-10-01

Full Text Available A study of transmittance and photoluminescence spectra on the growth of oxygen-rich ultra-thin ZnO films prepared by atomic layer deposition is reported. The structural transition from an amorphous to a polycrystalline state is observed upon increasing the thickness. The unusual behavior of the energy gap with thickness reflected by optical properties is attributed to the improvement of the crystalline structure resulting from a decreasing concentration of point defects at the growth of grains. The spectra of UV and visible photoluminescence emissions correspond to transitions near the band-edge and defect-related transitions. Additional emissions were observed from band-tail states near the edge. A high oxygen ratio and variable optical properties could be attractive for an application of atomic layer deposition (ALD deposited ultrathin ZnO films in optical sensors and biosensors.

Photoelectrochemical water splitting under visible light over anti-photocorrosive In{sub 2}O{sub 3}-coupling ZnO nanorod arrays photoanode

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yan, E-mail: zhangyanchem@qdu.edu.cn [Oceanology University of China, College of Chemistry and Chemical Engineering (China); Zhang, Jinqiu [Qingdao University, Faculty of Chemical Science and Engineering (China); Nie, Mengyan [University of Southampton, National Centre for Advanced Tribology at Southampton, School of Engineering Sciences (United Kingdom); Sun, Kai [Qingdao University, Faculty of Chemical Science and Engineering (China); Li, Chunhu [Oceanology University of China, College of Chemistry and Chemical Engineering (China); Yu, Jianqiang [Qingdao University, Faculty of Chemical Science and Engineering (China)

2015-07-15

In{sub 2}O{sub 3} quantum dots with a high crystallinity were deposited on the surface of ZnO nanorods through a chemistry bath method. The resulting In{sub 2}O{sub 3}-sensitizing ZnO nanorod arrays not only exhibited enhanced photoelectrochemical activity for water splitting under visible-light irradiation, but also possessed anti-photocorrosion property. The photo-induced charge-transfer property of In{sub 2}O{sub 3} could be improved greatly by coupling with ZnO. This observation demonstrated that the heterojunction at the interface between In{sub 2}O{sub 3} and ZnO could efficiently reduce the recombination of photo-induced electron–hole pairs and increase the lifetime of charge carriers and therefore enhance the photo-to-current efficiency of the In{sub 2}O{sub 3}–ZnO nanocrystalline arrays. It reveals that the heterojunction construction between two different semiconductors plays a very important role in determining the dynamic properties of their photogenerated charge carriers and their photo-to-current conversion efficiency.

Synthesis and self-assembly of dumbbell shaped ZnO sub-micron structures using low temperature chemical bath deposition technique

Energy Technology Data Exchange (ETDEWEB)

Borade, P. [National Centre for Nanoscience and Nanotechnology, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098 (India); Joshi, K.U. [Anton-Paar India Pvt. Ltd., Thane (W), 400607 (India); Gokarna, A.; Lerondel, G. [Laboratoire de Nanotechnologie et D' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 Rue Marie Curie, BP 2060, 10010 Troyes (France); Walke, P. [National Centre for Nanoscience and Nanotechnology, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098 (India); Late, D. [National Chemical Laboratory (NCL), Pune 400027 (India); Jejurikar, S.M., E-mail: jejusuhas@gmail.com [National Centre for Nanoscience and Nanotechnology, University of Mumbai, Kalina Campus, Santacruz (E), Mumbai 400098 (India)

2016-02-01

We report well dispersed horizontal growth of ZnO sub-micron structures using simplest technique ever known i.e. chemical bath deposition (CBD). A set of samples were prepared under two different cases A) dumbbell shaped ZnO grown in CBD bath and B) tubular ZnO structures evolved from dumbbell shaped structures by dissolution mechanism. Single phase wurtzite ZnO formation is confirmed using X-ray diffraction (XRD) technique in both cases. From the morphological investigations performed using scanning electron microscopy (SEM), sample prepared under case A indicate formation of hex bit tool (HBT) shaped ZnO crystals, which observed to self-organize to form dumbbell structures. Further these microstructures are then converted into tubular structures as a fragment of post CBD process. The possible mechanism responsible for the self-assembly of HBT units to form dumbbell structures is discussed. Observed free excitonic peak located at 370 nm in photoluminescence (PL) spectra recorded at 18 K indicate that the micro/nanostructures synthesized using CBD are of high optical quality. - Highlights: • Controlled growth of Dumbbell shaped ZnO using Chemical Bath Deposition (CBD). • Growth mechanism of dumbbell shaped ZnO by self-assembling was discussed. • Quick Transformation of ZnO dumbbell structures in to tubular structures by dissolution. • Sharp UV Emission at 370 nm from both dumbbell and tubular structures.

Effect of plasma composition on nanocrystalline diamond layers deposited by a microwave linear antenna plasma-enhanced chemical vapour deposition system

Czech Academy of Sciences Publication Activity Database

Taylor, Andrew; Ashcheulov, Petr; Čada, Martin; Fekete, Ladislav; Hubík, Pavel; Klimša, Ladislav; Olejníček, Jiří; Remeš, Zdeněk; Jirka, Ivan; Janíček, P.; Bedel-Pereira, E.; Kopeček, Jaromír; Mistrík, J.; Mortet, Vincent

2015-01-01

Roč. 212, č. 11 (2015), s. 2418-2423 ISSN 1862-6300 R&D Projects: GA ČR GA13-31783S; GA MŠk LO1409 Grant - others:FUNBIO(XE) CZ.2.16/3.1.00/21568 Institutional support: RVO:68378271 ; RVO:61388955 Keywords : diamond * electrical conductivity * nanocrystalline materials * optical emission spectroscopy * plasma enhanced chemical vapour deposition * SiC Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.648, year: 2015

Fabrication of Well-Aligned ZnO Nanorods Using a Composite Seed Layer of ZnO Nanoparticles and Chitosan Polymer.

Science.gov (United States)

Khun, Kimleang; Ibupoto, Zafar Hussain; AlSalhi, Mohamad S; Atif, Muhammad; Ansari, Anees A; Willander, Magnus

2013-09-30

In this study, by taking the advantage of both inorganic ZnO nanoparticles and the organic material chitosan as a composite seed layer, we have fabricated well-aligned ZnO nanorods on a gold-coated glass substrate using the hydrothermal growth method. The ZnO nanoparticles were characterized by the Raman spectroscopic techniques, which showed the nanocrystalline phase of the ZnO nanoparticles. Different composites of ZnO nanoparticles and chitosan were prepared and used as a seed layer for the fabrication of well-aligned ZnO nanorods. Field emission scanning electron microscopy, energy dispersive X-ray, high-resolution transmission electron microscopy, X-ray diffraction, and infrared reflection absorption spectroscopic techniques were utilized for the structural characterization of the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods on a gold-coated glass substrate. This study has shown that the ZnO nanorods are well-aligned, uniform, and dense, exhibit the wurtzite hexagonal structure, and are perpendicularly oriented to the substrate. Moreover, the ZnO nanorods are only composed of Zn and O atoms. An optical study was also carried out for the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods, and the obtained results have shown that the fabricated ZnO nanorods exhibit good crystal quality. This study has provided a cheap fabrication method for the controlled morphology and good alignment of ZnO nanorods, which is of high demand for enhancing the working performance of optoelectronic devices.

Fabrication of Well-Aligned ZnO Nanorods Using a Composite Seed Layer of ZnO Nanoparticles and Chitosan Polymer

Directory of Open Access Journals (Sweden)

Anees A. Ansari

2013-09-01

Full Text Available In this study, by taking the advantage of both inorganic ZnO nanoparticles and the organic material chitosan as a composite seed layer, we have fabricated well-aligned ZnO nanorods on a gold-coated glass substrate using the hydrothermal growth method. The ZnO nanoparticles were characterized by the Raman spectroscopic techniques, which showed the nanocrystalline phase of the ZnO nanoparticles. Different composites of ZnO nanoparticles and chitosan were prepared and used as a seed layer for the fabrication of well-aligned ZnO nanorods. Field emission scanning electron microscopy, energy dispersive X-ray, high-resolution transmission electron microscopy, X-ray diffraction, and infrared reflection absorption spectroscopic techniques were utilized for the structural characterization of the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods on a gold-coated glass substrate. This study has shown that the ZnO nanorods are well-aligned, uniform, and dense, exhibit the wurtzite hexagonal structure, and are perpendicularly oriented to the substrate. Moreover, the ZnO nanorods are only composed of Zn and O atoms. An optical study was also carried out for the ZnO nanoparticles/chitosan seed layer-coated ZnO nanorods, and the obtained results have shown that the fabricated ZnO nanorods exhibit good crystal quality. This study has provided a cheap fabrication method for the controlled morphology and good alignment of ZnO nanorods, which is of high demand for enhancing the working performance of optoelectronic devices.

Structural, nanomechanical and variable range hopping conduction behavior of nanocrystalline carbon thin films deposited by the ambient environment assisted filtered cathodic jet carbon arc technique

Energy Technology Data Exchange (ETDEWEB)

Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Rawal, Ishpal; Tripathi, R.K. [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Srivastava, A.K. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Kumar, Mahesh [Ultrafast Opto-Electronics and Tetrahertz Photonics Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India)

2015-04-15

Highlights: • Nanocrystalline carbon thin films are grown by filtered cathodic jet carbon arc process. • Effect of gaseous environment on the properties of carbon films has been studied. • The structural and nanomechanical properties of carbon thin films have been studied. • The VRH conduction behavior in nanocrystalline carbon thin films has been studied. - Abstract: This paper reports the deposition and characterization of nanocrystalline carbon thin films by filtered cathodic jet carbon arc technique assisted with three different gaseous environments of helium, nitrogen and hydrogen. All the films are nanocrystalline in nature as observed from the high resolution transmission electron microscopic (HRTEM) measurements, which suggests that the nanocrystallites of size ∼10–50 nm are embedded though out the amorphous matrix. X-ray photoelectron spectroscopic studies suggest that the film deposited under the nitrogen gaseous environment has the highest sp{sup 3}/sp{sup 2} ratio accompanied with the highest hardness of ∼18.34 GPa observed from the nanoindentation technique. The film deposited under the helium gaseous environment has the highest ratio of the area under the Raman D peak to G peak (A{sub D}/A{sub G}) and the highest conductivity (∼2.23 S/cm) at room temperature, whereas, the film deposited under the hydrogen environment has the lowest conductivity value (2.27 × 10{sup −7} S/cm). The temperature dependent dc conduction behavior of all the nanocrystalline carbon thin films has been analyzed in the light of Mott’s variable range hopping (VRH) conduction mechanism and observed that all the films obey three dimension VRH conduction mechanism for the charge transport.

Room-temperature synthesis of ultraviolet-emitting nanocrystalline GaN films using photochemical vapor deposition

International Nuclear Information System (INIS)

Yamazaki, Shunsuke; Yatsui, Takashi; Ohtsu, Motoichi; Kim, Taw-Won; Fujioka, Hiroshi

2004-01-01

We fabricated UV-emitting nanocrystalline gallium nitride (GaN) films at room temperature using photochemical vapor deposition (PCVD). For the samples synthesized at room temperature with V/III ratios exceeding 5.0x10 4 , strong photoluminescence peaks at 3.365 and 3.310 eV, which can be ascribed to transitions in a mixed phase of cubic and hexagonal GaN, were observed at 5 K. A UV emission spectrum with a full width at half-maximum of 100 meV was observed, even at room temperature. In addition, x-ray photoelectron spectroscopy measurement revealed that the film deposited by PCVD at room temperature was well nitridized

Controlling the quality of nanocrystalline silicon made by hot-wire chemical vapor deposition by using a reverse H2 profiling technique

NARCIS (Netherlands)

Li, H. B. T.; Franken, R.H.; Stolk, R.L.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

2008-01-01

Hydrogen profiling, i.e., decreasing the H2 dilution during deposition, is a well-known technique to maintain a proper crystalline ratio of the nanocrystalline (nc-Si:H) absorber layers of plasma-enhanced chemical vapor-deposited (PECVD) thin film solar cells. With this technique a large increase in

Giant magneto-impedance effect on nanocrystalline microwires with conductive layer deposit

International Nuclear Information System (INIS)

Wang, R.L.; Zhao, Z.J.; Liu, L.P.; Yuan, W.Z.; Yang, X.L.

2005-01-01

In this study, the giant magneto-impedance effect on Fe-based glass-coated nanocrystalline microwires with and without an additional outer copper layer was investigated. Experiment results showed that the magneto-impedance ratio of the wires with a layer of deposited copper is higher at low frequencies and lower at high frequencies (above 50 MHz), as compared to that of the microwires without an outer copper layer. The peak MI magnetic field, corresponding to the maximum of the magneto-impedance ratio shifts towards higher field values with increasing coating thickness of copper layer. The results are explained in terms of electro-magnetic interactions between the conductive layer and the ferromagnetic core

Crystalline nanostructured Cu doped ZnO thin films grown at room temperature by pulsed laser deposition technique and their characterization

Energy Technology Data Exchange (ETDEWEB)

Drmosh, Qasem A. [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Rao, Saleem G.; Yamani, Zain H. [Laser Research Group, Department of Physics, Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Gondal, Mohammed A., E-mail: magondal@kfupm.edu.sa [Laser Research Group, Department of Physics, Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

2013-04-01

We report structural and optical properties of Cu doped ZnO (ZnO:Cu) thin films deposited on glass substrate at room temperature by pulsed laser deposition (PLD) method without pre and post annealing contrary to all previous reports. For preparation of (ZnO:Cu) composites pure Zn and Cu targets in special geometrical arrangements were exposed to 248 nm radiations generated by KrF exciter laser. The laser energy was 200 mJ with 10 Hz frequency and 20 ns pulse width. The effect of Cu concentration on crystal structure, morphology, and optical properties were investigated by XRD, FESEM and photoluminescence spectrometer respectively. A systematic shift in ZnO (0 0 2) peak with Cu concentration observed in XRD spectra demonstrated that Cu ion has been incorporated in ZnO lattice. Uniform film with narrow size range grains were observed in FESEM images. The photoluminescence (PL) spectra measured at room temperature revealed a systematic red shift in ZnO emission peak and decrease in the band gap with the increase in Cu concentration. These results entail that PLD technique can be realized to deposit high quality crystalline ZnO and ZnO:Cu thin films without pre and post heat treatment which is normally practiced worldwide for such structures.

Synthesis of Colloidal ZnO Nanoparticles and Deposit of Thin Films by Spin Coating Technique

Directory of Open Access Journals (Sweden)

Jose Alberto Alvarado

2013-01-01

Full Text Available ZnO colloidal nanoparticles were synthesized, the average size of these nanoparticles is around 25 nm with hexagonal form. It was noted that stabilization depends directly on the purifying process; in this work we do not change the nature of the solution as a difference from Meulekamp's method, and we do not use any alkanes to remove the byproducts; only a centrifuge to remove those ones was used, thereby the stabilization increases up to 24 days. It is observed from the results that only three times of washing is enough to prevent the rapid aging process. The effect of annealing process on the composition, size, and geometrical shape of ZnO nanoparticles was studied in order to know whether the annealing process affects the crystallization and growth of the nanoparticles. After the synthesis, the colloidal nanoparticles were deposited by spin coating technique showing that the formed nanoparticles have no uniformly deposition pattern. But is possible to deposit those ones in glass substrates. A possible deposition process of the nanoparticles is proposed.

Nanostructured ZnO thin films by chemical bath deposition in basic aqueous ammonia solutions for photovoltaic applications

Energy Technology Data Exchange (ETDEWEB)

Chu, J.B.; Huang, S.M.; Zhang, D.W.; Bian, Z.Q.; Li, X.D.; Sun, Z. [East China Normal University, Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, Shanghai (China); Yin, X.J. [Singapore Polytechnic, Advanced Materials Technology Center, Singapore (Singapore)

2009-06-15

This paper presents further insights and observations of the chemical bath deposition (CBD) of ZnS thin films using an aqueous medium involving Zn-salt, ammonium sulfate, aqueous ammonia, and thiourea. Results on physical and chemical properties of the grown layers as a function of ammonia concentration are reported. Physical and chemical properties were analyzed using scanning electron microscopy (SEM), X-ray energy dispersive (EDX), and X-ray diffraction (XRD). Rapid growth of nanostructured ZnO films on fluorine-doped SnO{sub 2} (FTO) glass substrates was developed. ZnO films crystallized in a wurtzite hexagonal structure and with a very small quantity of Zn(OH){sub 2} and ZnS phases were obtained for the ammonia concentration ranging from 0.75 to 2.0 M. Flower-like and columnar nanostructured ZnO films were deposited in two ammonia concentration ranges, respectively: one between 0.75 and 1.0 M and the other between 1.4 and 2.0 M. ZnS films were formed with a high ammonia concentration of 3.0 M. The formation mechanisms of ZnO, Zn(OH){sub 2}, and ZnS phases were discussed in the CBD process. The developed technique can be used to directly and rapidly grow nanostructured ZnO film photoanodes. Annealed ZnO nanoflower and columnar nanoparticle films on FTO substrates were used as electrodes to fabricate the dye sensitized solar cells (DSSCs). The DSSC based on ZnO-nanoflower film showed an energy conversion efficiency of 0.84%, which is higher compared to that (0.45%) of the cell being constructed using a photoanode of columnar nanoparticle ZnO film. The results have demonstrated the potential applications of CBD nanostructured ZnO films for photovoltaic cells. (orig.)

Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

Science.gov (United States)

Singh, Ajaib; Schipmann, Susanne; Mathur, Aakash; Pal, Dipayan; Sengupta, Amartya; Klemradt, Uwe; Chattopadhyay, Sudeshna

2017-08-01

The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2-7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

Structural, optical and magnetic characterization of Ru doped ZnO nanorods

International Nuclear Information System (INIS)

Kumar, Sanjeev; Kaur, Palvinder; Chen, C.L.; Thangavel, R.; Dong, C.L.; Ho, Y.K.; Lee, J.F.; Chan, T.S.; Chen, T.K.; Mok, B.H.; Rao, S.M.; Wu, M.K.

2014-01-01

Graphical abstract: Ruthenium (Ru = 0%, 1% and 2%) doped nano-crystalline zinc oxide (ZnO) nanorods were synthesized by using well-known sol–gel technique. X-ray diffraction (XRD) results show that Ru (0%, 1% and 2%) doped ZnO nanorods crystallized in the wurtzite structure having space group C 3v (P6 3 mc). Williamson and Hall plot reveal that in the nanoscale dimensions, incorporation of Ru induced the tensile strain in ZnO host matrix. Photoluminescence (PL) and Raman studies of Ru doped ZnO nanorods show the formation of singly ionized oxygen vacancies which may account for the observed room temperature ferromagnetism (RTFM) in 2% Ru doped ZnO. X-ray absorption spectroscopy (XAS) reveals that Ru replace the Zn atoms in the host lattice and maintain the crystal symmetry with slightly lattice distortion. Highlights: • Ru doped ZnO nanorods crystallized in the wurtzite structure having space group C 3v (P6 3 mc). • PL and Raman studies show the formation of singly ionized oxygen vacancies in 2% Ru doped ZnO. • XAS reveals that Ru replace the Zn atoms in the host lattice with slightly lattice distortion. • Doping of Ru in ZnO nanostructures gives rise to RTFM ordering. -- Abstract: Ruthenium (Ru = 0%, 1% and 2%) doped nano-crystalline zinc oxide (ZnO) nanorods were synthesized by using well-known sol–gel technique. X-ray diffraction (XRD) results show that Ru (0%, 1% and 2%) doped ZnO nanorods crystallized in the wurtzite structure having space group C 3v (P6 3 mc). Williamson and Hall plot reveal that in the nanoscale dimensions, incorporation of Ru induced the tensile strain in ZnO host matrix. Photoluminescence (PL) and Raman studies of Ru doped ZnO nanorods show the formation of singly ionized oxygen vacancies which may account for the observed room temperature ferromagnetism (RTFM) in 2% Ru doped ZnO. X-ray absorption spectroscopy (XAS) reveals that Ru replace the Zn atoms in the host lattice and maintain the crystal symmetry with slightly lattice

Growth of vertically aligned ZnO nanorods using textured ZnO films

Directory of Open Access Journals (Sweden)

Meléndrez Manuel

2011-01-01

Full Text Available Abstract A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100 substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.

Bipolar resistive switching characteristics of low temperature grown ZnO thin films by plasma-enhanced atomic layer deposition

International Nuclear Information System (INIS)

Zhang Jian; Yang Hui; Zhang Qilong; Dong Shurong; Luo, J. K.

2013-01-01

ZnO films deposited by plasma-enhanced atomic layer deposition (PEALD) have been used to investigate resistive memory behavior. The bipolar resistance switching properties were observed in the Al/PEALD-ZnO/Pt devices. The resistance ratio for the high and low resistance states (HRS/LRS) is more than 10 3 , better than ZnO devices deposited by other methods. The dominant conduction mechanisms of HRS and LRS are trap-controlled space charge limited current and Ohmic behavior, respectively. The resistive switching behavior is induced upon the formation/disruption of conducting filaments. This study demonstrated that the PEALD-ZnO films have better properties for the application in 3D resistance random access memory.

Superhydrophobic multi-scale ZnO nanostructures fabricated by chemical vapor deposition method.

Science.gov (United States)

Zhou, Ming; Feng, Chengheng; Wu, Chunxia; Ma, Weiwei; Cai, Lan

2009-07-01

The ZnO nanostructures were synthesized on Si(100) substrates by chemical vapor deposition (CVD) method. Different Morphologies of ZnO nanostructures, such as nanoparticle film, micro-pillar and micro-nano multi-structure, were obtained with different conditions. The results of XRD and TEM showed the good quality of ZnO crystal growth. Selected area electron diffraction analysis indicates the individual nano-wire is single crystal. The wettability of ZnO was studied by contact angle admeasuring apparatus. We found that the wettability can be changed from hydrophobic to super-hydrophobic when the structure changed from smooth particle film to single micro-pillar, nano-wire and micro-nano multi-scale structure. Compared with the particle film with contact angle (CA) of 90.7 degrees, the CA of single scale microstructure and sparse micro-nano multi-scale structure is 130-140 degrees, 140-150 degrees respectively. But when the surface is dense micro-nano multi-scale structure such as nano-lawn, the CA can reach to 168.2 degrees . The results indicate that microstructure of surface is very important to the surface wettability. The wettability on the micro-nano multi-structure is better than single-scale structure, and that of dense micro-nano multi-structure is better than sparse multi-structure.

Residual stress and bending strength of ZnO films deposited on polyimide sheet by RF sputtering system

Energy Technology Data Exchange (ETDEWEB)

Kusaka, Kazuya, E-mail: kusaka@tokushima-u.ac.jp [Institute of Technology and Science, Tokushima University, 2-1, Minamijosanjima, Tokushima, Tokushima 7708506 (Japan); Maruoka, Yutaka, E-mail: ymaruoka1116@gmail.com [Graduate School of Advanced Technology and Science, Tokushima University, 2-1, Minamijosanjima, Tokushima, Tokushima 7708506 (Japan); Matsue, Tatsuya, E-mail: tmatsue@mat.niihama-nct.ac.jp [Department of Environmental Materials Engineering National Institute of Technology, NIIHAMA College, 7-1, Yakumo-cho, Niihama, Ehime 7928580 (Japan)

2016-05-15

Zinc oxide (ZnO) films were deposited on a soft polyimide sheet substrate by radio frequency sputtering with a ZnO powder target, and the films' crystal orientations and residual stress were investigated using x-ray diffraction as a function of substrate temperature. C-axis oriented ZnO films were achieved using this ZnO powder target method. The ZnO films exhibited high compressive residual stresses between −0.7 and −1.4 GPa. Finally, the authors examined the strength of the obtained film by applying tensile bending loads. No cracks were observed on the surfaces of the ZnO films after a bending test using cylinders with diameters >25 mm. After a bending test using a cylinder with a diameter of 19 mm, large cracks were formed on the films. Therefore, the authors concluded that the tensile bending strength of the obtained films was greater than ∼420 MPa.

Sputter deposited gallium doped ZnO for TCO applications

Energy Technology Data Exchange (ETDEWEB)

Dietrich, Marc; Kronenberger, Achim; Polity, Angelika; Meyer, Bruno [I. Physikalisches Institut, Justus Liebig Universitaet Giessen (Germany); Blaesing, Juergen; Krost, Alois [FNW/IEP/AHE, Otto-von-Guericke Universitaet Magdeburg (Germany)

2010-07-01

Transparent conducting oxides to be used for flat panel or display applications should exhibit low electrical resistivity in line with a high optical transmission in the visible spectral range. Today indium-tin-oxide is the material which meets these requirements best. However, the limited availability of indium makes it useful to search for alternatives and ZnO doped with group III elements are promising candidates. While the Al doping in high concentrations causes problems due to the formation of insulating Al-oxides, Gallium related oxides are typically n-type conducting wide band gap semiconductors. Therefore we deposited Gallium doped ZnO thin films on quartz and sapphire substrates by radio frequency magnetron sputtering with a ZnO/Ga{sub 2}O{sub 3}(3at%) composite target. The substrate temperature and the oxygen flow during the sputtering process were varied to optimise the layer properties. Introducing oxygen to the sputtering gas allowed to vary the resistivity of the films by three orders of magnitude from about 1 {omega}cm down to less than 1 m{omega}cm.

Silver film on nanocrystalline TiO{sub 2} support: Photocatalytic and antimicrobial ability

Energy Technology Data Exchange (ETDEWEB)

Vukoje, Ivana D., E-mail: ivanav@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Tomašević-Ilić, Tijana D., E-mail: tommashev@gmail.com [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Zarubica, Aleksandra R., E-mail: zarubica2000@yahoo.com [Department of Chemistry, Faculty of Science and Mathematics, University of Niš, Višegradska 33, 18000 Niš (Serbia); Dimitrijević, Suzana, E-mail: suzana@tmf.bg.ac.rs [Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade (Serbia); Budimir, Milica D., E-mail: mickbudimir@gmail.com [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Vranješ, Mila R., E-mail: mila@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Šaponjić, Zoran V., E-mail: saponjic@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia); Nedeljković, Jovan M., E-mail: jovned@vinca.rs [Vinča Institute of Nuclear Sciences, University of Belgrade, P.O. Box 522, 11000 Belgrade (Serbia)

2014-12-15

Highlights: • Simple photocatalytic rout for deposition of Ag on nanocrystalline TiO{sub 2} films. • High antibactericidal efficiency of deposited Ag on TiO{sub 2} support. • Improved photocatalytic performance of TiO{sub 2} films in the presence of deposited Ag. - Abstract: Nanocrystalline TiO{sub 2} films were prepared on glass slides by the dip coating technique using colloidal solutions consisting of 4.5 nm particles as a precursor. Photoirradiation of nanocrystalline TiO{sub 2} film modified with alanine that covalently binds to the surface of TiO{sub 2} and at the same time chelate silver ions induced formation of metallic silver film. Optical and morphological properties of thin silver films on nanocrystalline TiO{sub 2} support were studied by absorption spectroscopy and atomic force microscopy. Improvement of photocatalytic performance of nanocrystalline TiO{sub 2} films after deposition of silver was observed in degradation reaction of crystal violet. Antimicrobial ability of deposited silver films on nanocrystalline TiO{sub 2} support was tested in dark as a function of time against Escherichia coli, Staphylococcus aureus, and Candida albicans. The silver films ensured maximum cells reduction of both bacteria, while the fungi reduction reached satisfactory 98.45% after 24 h of contact.

Direct Coating of Nanocrystalline Diamond on Steel

Science.gov (United States)

Tsugawa, Kazuo; Kawaki, Shyunsuke; Ishihara, Masatou; Hasegawa, Masataka

2012-09-01

Nanocrystalline diamond films have been successfully deposited on stainless steel substrates without any substrate pretreatments to promote diamond nucleation, including the formation of interlayers. A low-temperature growth technique, 400 °C or lower, in microwave plasma chemical vapor deposition using a surface-wave plasma has cleared up problems in diamond growth on ferrous materials, such as the surface graphitization, long incubation time, substrate softening, and poor adhesion. The deposited nanocrystalline diamond films on stainless steel exhibit good adhesion and tribological properties, such as a high wear resistance, a low friction coefficient, and a low aggression strength, at room temperature in air without lubrication.

Direct deposition of patterned nanocrystalline CVD diamond using an electrostatic self-assembly method with nanodiamond particles

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung-Koo; Kim, Jong-Hoon; Jeong, Min-Goon; Lim, Dae-Soon [Department of Materials Science and Engineering, Korea University, Anam-Dong 5-1, Seoungbuk-Ku, Seoul 136-713 (Korea, Republic of); Song, Min-Jung, E-mail: dslim@korea.ac.kr [Center for Advanced Device Materials, Korea University, Anam-Dong 5-1, Seoungbuk-Ku, Seoul 136-713 (Korea, Republic of)

2010-12-17

Micron-sized and precise patterns of nanocrystalline CVD diamond were fabricated successfully on substrates using dispersed nanodiamond particles, charge connection by electrostatic self-assembly, and photolithography processes. Nanodiamond particles which had been dispersed using an attritional milling system were attached electrostatically on substrates as nuclei for diamond growth. In this milling process, poly sodium 4-styrene sulfonate (PSS) was added as an anionic dispersion agent to produce the PSS/nanodiamond conjugates. Ultra dispersed nanodiamond particles with a {zeta}-potential and average particle size of - 60.5 mV and {approx} 15 nm, respectively, were obtained after this milling process. These PSS/nanodiamond conjugates were attached electrostatically to a cationic polyethyleneimine (PEI) coated surface on to which a photoresist had been patterned in an aqueous solution of the PSS/nanodiamond conjugated suspension. A selectively seeded area was formed successfully using the above process. A hot filament chemical vapor deposition system was used to synthesize the nanocrystalline CVD diamond on the seeded area. Micron-sized, thin and precise nanocrystalline CVD diamond patterns with a high nucleation density (3.8 {+-} 0.4 x 10{sup 11} cm{sup -2}) and smooth surface were consequently fabricated.

Direct deposition of patterned nanocrystalline CVD diamond using an electrostatic self-assembly method with nanodiamond particles

International Nuclear Information System (INIS)

Lee, Seung-Koo; Kim, Jong-Hoon; Jeong, Min-Goon; Lim, Dae-Soon; Song, Min-Jung

2010-01-01

Micron-sized and precise patterns of nanocrystalline CVD diamond were fabricated successfully on substrates using dispersed nanodiamond particles, charge connection by electrostatic self-assembly, and photolithography processes. Nanodiamond particles which had been dispersed using an attritional milling system were attached electrostatically on substrates as nuclei for diamond growth. In this milling process, poly sodium 4-styrene sulfonate (PSS) was added as an anionic dispersion agent to produce the PSS/nanodiamond conjugates. Ultra dispersed nanodiamond particles with a ζ-potential and average particle size of - 60.5 mV and ∼ 15 nm, respectively, were obtained after this milling process. These PSS/nanodiamond conjugates were attached electrostatically to a cationic polyethyleneimine (PEI) coated surface on to which a photoresist had been patterned in an aqueous solution of the PSS/nanodiamond conjugated suspension. A selectively seeded area was formed successfully using the above process. A hot filament chemical vapor deposition system was used to synthesize the nanocrystalline CVD diamond on the seeded area. Micron-sized, thin and precise nanocrystalline CVD diamond patterns with a high nucleation density (3.8 ± 0.4 x 10 11 cm -2 ) and smooth surface were consequently fabricated.

The influence of annealing in nitrogen atmosphere on the electrical, optical and structural properties of spray- deposited ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Ikhmayies, S.J. [Applied Science Private Univ., Amman (Jordan). Dept. of Physics; Abu El-Haija, N.M.; Ahmad-Bitar, R.N. [Jordan Univ., Amman (Jordan). Dept. of Physics

2009-07-01

Thin-film zinc oxide (ZnO) has many applications in solar cell technology and is considered to be a candidate for the substitution of indium tin oxide and tin oxide. ZnO thin films can be prepared by thermal evaporation, rf-sputtering, atomic layer deposition, chemical vapor deposition, sol-gel, laser ablation and spray pyrolysis technique. Spray pyrolysis has received much attention because of its simplicity and low cost. In this study, large area and highly uniform polycrystalline ZnO thin films were produced by spray pyrolysis using a home-made spraying system on glass substrates at 450 degrees C. The electrical, optical and structural properties of the ZnO films were enhanced by annealing the thin films in nitrogen atmosphere. X-ray diffraction revealed that the films are polycrystalline with a hexagonal wurtzite structure. The preferential orientation did not change with annealing, but XRD patterns revealed that some very weak lines had grown. There was no noticeable increase in the grain size. The transmittance of the films increased as a result of annealing. It was concluded that post-deposition annealing is essential to improve the quality of the ZnO thin films. The electrical properties improved due to a decrease in resistivity. 13 refs., 5 figs.

Luminescence property and large-scale production of ZnO nanowires by current heating deposition

International Nuclear Information System (INIS)

Singjai, P.; Jintakosol, T.; Singkarat, S.; Choopun, S.

2007-01-01

Large-scale production for ZnO nanowires has been demonstrated by current heating deposition. Based on the use of a solid-vapor phase carbothermal sublimation technique, a ZnO-graphite mixed rod was placed between two copper bars and gradually heated by passing current through it under constant flowing of argon gas at atmospheric pressure. The product seen as white films deposited on the rod surface was separated for further characterizations. The results have shown mainly comb-like structures of ZnO nanowires in diameter ranging from 50 to 200 nm and length up to several tens micrometers. From optical testing, ionoluminescence spectra of as-grown and annealed samples have shown high green emission intensities centered at 510 nm. In contrast, the small UV peak centered at 390 nm was observed clearly in the as-grown sample which almost disappeared after the annealing treatment

Thermal stability of grain boundaries in nanocrystalline Zn studied by positron lifetime spectroscopy

International Nuclear Information System (INIS)

Zhou Kai; Li Hui; Pang Jinbiao; Wang Zhu

2012-01-01

Nanocrystalline Zn prepared by compacting nanoparticles with mean grain size about 55 nm at 15 MPa has been studied by positron lifetime spectroscopy. For the bulk Zn sample, the vacancy defect is annealed out at about 350 °C, but for the nanocrystalline Zn sample, the vacancy cluster in grain boundaries is quite difficult to be annealed out even at very high temperature (410 °C). In the grain boundaries of nanocrystalline Zn, the small free volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ 1 ). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τ av ), which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. This stabilization is very important for the nanocrystalline materials using as radiation resistant materials.

Defect dynamics in Li substituted nanocrystalline ZnO: A spectroscopic analysis

Science.gov (United States)

Ghosh, S.; Nambissan, P. M. G.; Thapa, S.; Mandal, K.

2014-12-01

Very recently, vacancy-type defects have been found to play a major role in stabilizing d0 ferromagnetism in various low dimensional ZnO systems. In this context, the evolution of vacancy-type defects within the ZnO nanocrystals due to the doping of ZnO by alkali metal lithium (Li) is investigated using X-ray photoelectron (XPS), photoluminescence (PL) and positron annihilation spectroscopy (PAS). Li-doping is found to have significant effects in modifying the vacancy-type defects, especially the Zn vacancy (VZn) defects within the ZnO lattice. XPS measurement indicated that initially the Li1+ ions substitute at Zn2+ sites, but when Li concentration exceeds 7 at%, excess Li starts to move through the interstitial sites. The increase in positron lifetime components and the lineshape S-parameter obtained from coincident Doppler broadening spectra with Li-doping indicated an enhancement of VZn defect concentration within the doped ZnO lattice. The vacancy type defects, initially of the predominant configuration VZn+O+Zn got reduced to neutral ZnO divacancies due to the partial recombination by the doped Li1+ ions but, when the doping concentration exceeded 7 at% and Li1+ ions started migrating to the interstitials, positron diffusion is partly impeded and this results in reduced probability of annihilation. PL spectra have shown intense green and yellow-orange emission due to the stabilization of a large number of VZn defects and Li substitutional (LiZn) defects respectively. Hence Li can be a very useful dopant in stabilizing and modifying significant amount of Zn vacancy-defects which can play a useful role in determining the material behavior.

Defect dynamics in Li substituted nanocrystalline ZnO: A spectroscopic analysis

International Nuclear Information System (INIS)

Ghosh, S.; Nambissan, P.M.G.; Thapa, S.; Mandal, K.

2014-01-01

Very recently, vacancy-type defects have been found to play a major role in stabilizing d 0 ferromagnetism in various low dimensional ZnO systems. In this context, the evolution of vacancy-type defects within the ZnO nanocrystals due to the doping of ZnO by alkali metal lithium (Li) is investigated using X-ray photoelectron (XPS), photoluminescence (PL) and positron annihilation spectroscopy (PAS). Li-doping is found to have significant effects in modifying the vacancy-type defects, especially the Zn vacancy (V Zn ) defects within the ZnO lattice. XPS measurement indicated that initially the Li 1+ ions substitute at Zn 2+ sites, but when Li concentration exceeds 7 at%, excess Li starts to move through the interstitial sites. The increase in positron lifetime components and the lineshape S-parameter obtained from coincident Doppler broadening spectra with Li-doping indicated an enhancement of V Zn defect concentration within the doped ZnO lattice. The vacancy type defects, initially of the predominant configuration V Zn+O+Zn got reduced to neutral ZnO divacancies due to the partial recombination by the doped Li 1+ ions but, when the doping concentration exceeded 7 at% and Li 1+ ions started migrating to the interstitials, positron diffusion is partly impeded and this results in reduced probability of annihilation. PL spectra have shown intense green and yellow-orange emission due to the stabilization of a large number of V Zn defects and Li substitutional (Li Zn ) defects respectively. Hence Li can be a very useful dopant in stabilizing and modifying significant amount of Zn vacancy-defects which can play a useful role in determining the material behavior

Electrospray Deposition of ZnO Thin Films and Its Application to Gas Sensors

Directory of Open Access Journals (Sweden)

Wenwang Li

2018-02-01

Full Text Available Electrospray is a simple and cost-effective method to fabricate micro-structured thin films. This work investigates the electrospray process of ZnO patterns. The effects of experimental parameters on jet characteristics and electrosprayed patterns are studied. The length of stable jets increases with increasing applied voltage and flow rate, and decreases with increasing nozzle-to-substrate distance, while electrospray angles exhibit an opposite trend with respect to the stable jet lengths. The diameter of electrosprayed particles decreases with increasing applied voltage, and increases with flow rate. Furthermore, an alcohol gas sensor is presented. The ZnAc is calcined into ZnO, which reveals good repeatability and stability of response in target gas. The sensing response, defined as the resistance ratio of R0/Rg, where R0 and Rg are resistance of ZnO in air and alcohol gas, increases with the concentration of alcohol vapors and electrospray deposition time.

Growth and characterization of ZnO films deposited by chemical bath and annealed by microwaves (CBD-A{mu}W)

Energy Technology Data Exchange (ETDEWEB)

DIaz-Reyes, J [CIBA-IPN, Ex-Hacienda de San Juan Molino, Km. 1.5, Tepetitla, Tlaxcala, 90700 (Mexico); Martinez-Juarez, J; Garcia, M L; Galeazzi, R [CIDS-ICUAP, BUAP, 14 Sur y San Claudio S/N, CU. Edif. No. 137, Col. San Manuel, Puebla, Puebla 72570 (Mexico); Juarez, G, E-mail: jdiazr2001@yahoo.com [DIE-SEES, CINVESTAV-IPN, A. P. 14-740, Mexico, D. F. 07000 (Mexico)

2010-06-15

A study of the growth and the physical properties of ZnO films deposited by chemical bath technique and annealed by microwave are presented. For the deposition solution the molar ratio between zinc nitrate and urea is varied in a range of 1:1... 1:10. By X-ray obtains that layers have hexagonal polycrystalline wurtzite type unitary cell. The Raman spectra show the first order experimental Raman spectra of ZnO. The first order Raman modes are identified in the ZnO Raman spectra. The 300K photoluminescence shows radiative bands labelled by red, yellow, green and violet bands, which are associated to defects of oxygen and zinc vacancies. By EDS measurements determined their stoichiometry, which allows relating it with the intensity of radiative bands associated to oxygen and zinc vacancies.

Morphology development and oriented growth of single crystalline ZnO nanorod

International Nuclear Information System (INIS)

Wu Lili; Wu Youshi; Lue Wei; Wei Huiying; Shi Yuanchang

2005-01-01

Single crystalline ZnO nanorods were achieved by the assembly of nanocrystallines in tens of nanometer under hydrothermal conditions with the assistance of surfactant cetyltrimethylammonium bromide (CTAB). The obtained nanorod has rough surface as a result of oriented attachment growth. Transmission electron microscope (TEM) images showed the morphology evolution of the nanorod at different reaction time. Defects were observed and porous structure was left after the assembly of hundreds of nanocrystalline building blocks. Effect of pH condition on the morphology of the nanorod was also investigated

Morphological and optical properties changes in nanocrystalline Si (nc-Si) deposited on porous aluminum nanostructures by plasma enhanced chemical vapor deposition for Solar energy applications

Energy Technology Data Exchange (ETDEWEB)

Ghrib, M., E-mail: mondherghrib@yahoo.fr [Laboratoire de Photovoltaique (L.P.V.), Centre de Recherche et des Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia); Gaidi, M.; Ghrib, T.; Khedher, N. [Laboratoire de Photovoltaique (L.P.V.), Centre de Recherche et des Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia); Ben Salam, M. [L3M, Department of Physics, Faculty of Sciences of Bizerte, 7021 Zarzouna (Tunisia); Ezzaouia, H. [Laboratoire de Photovoltaique (L.P.V.), Centre de Recherche et des Technologies de l' Energie, BP 95, Hammam-Lif 2050 (Tunisia)

2011-08-15

Photoluminescence (PL) spectroscopy was used to determine the electrical band gap of nanocrystalline silicon (nc-Si) deposited by plasma enhancement chemical vapor deposition (PECVD) on porous alumina structure by fitting the experimental spectra using a model based on the quantum confinement of electrons in Si nanocrystallites having spherical and cylindrical forms. This model permits to correlate the PL spectra to the microstructure of the porous aluminum silicon layer (PASL) structure. The microstructure of aluminum surface layer and nc-Si films was systematically studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD). It was found that the structure of the nanocrystalline silicon layer (NSL) is dependent of the porosity (void) of the porous alumina layer (PAL) substrate. This structure was performed in two steps, namely the PAL substrate was prepared using sulfuric acid solution attack on an Al foil and then the silicon was deposited by plasma enhanced chemical vapor deposition (PECVD) on it. The optical constants (n and k as a function of wavelength) of the deposited films were obtained using variable angle spectroscopic ellipsometry (SE) in the UV-vis-NIR regions. The SE spectrum of the porous aluminum silicon layer (PASL) was modeled as a mixture of void, crystalline silicon and aluminum using the Cauchy model approximation. The specific surface area (SSA) was estimated and was found to decrease linearly when porosity increases. Based on this full characterization, it is demonstrated that the optical characteristics of the films are directly correlated to their micro-structural properties.

Morphological and optical properties changes in nanocrystalline Si (nc-Si) deposited on porous aluminum nanostructures by plasma enhanced chemical vapor deposition for Solar energy applications

International Nuclear Information System (INIS)

Ghrib, M.; Gaidi, M.; Ghrib, T.; Khedher, N.; Ben Salam, M.; Ezzaouia, H.

2011-01-01

Photoluminescence (PL) spectroscopy was used to determine the electrical band gap of nanocrystalline silicon (nc-Si) deposited by plasma enhancement chemical vapor deposition (PECVD) on porous alumina structure by fitting the experimental spectra using a model based on the quantum confinement of electrons in Si nanocrystallites having spherical and cylindrical forms. This model permits to correlate the PL spectra to the microstructure of the porous aluminum silicon layer (PASL) structure. The microstructure of aluminum surface layer and nc-Si films was systematically studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffraction (XRD). It was found that the structure of the nanocrystalline silicon layer (NSL) is dependent of the porosity (void) of the porous alumina layer (PAL) substrate. This structure was performed in two steps, namely the PAL substrate was prepared using sulfuric acid solution attack on an Al foil and then the silicon was deposited by plasma enhanced chemical vapor deposition (PECVD) on it. The optical constants (n and k as a function of wavelength) of the deposited films were obtained using variable angle spectroscopic ellipsometry (SE) in the UV-vis-NIR regions. The SE spectrum of the porous aluminum silicon layer (PASL) was modeled as a mixture of void, crystalline silicon and aluminum using the Cauchy model approximation. The specific surface area (SSA) was estimated and was found to decrease linearly when porosity increases. Based on this full characterization, it is demonstrated that the optical characteristics of the films are directly correlated to their micro-structural properties.

Annealed Ce{sup 3+}-doped ZnO flower-like morphology synthesized by chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Koao, Lehlohonolo F., E-mail: koaolf@ufs.ac.za [Department of Physics, University of the Free State (Qwa Qwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, Francis B.; Tsega, Moges [Department of Physics, University of the Free State (Qwa Qwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, Hendrik C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

2016-01-01

We have successfully synthesized ZnO:xmol% Ce{sup 3+} (0≤x≤10 mol%) doped nanopowders via the chemical bath deposition method (CBD) technique at low temperature (80 °C) and annealed in air at 700 °C. The X-ray diffraction patterns showed that all the undoped and Ce-doped ZnO nanopowders have a hexagonal wurtzite polycrystalline structure with an average crystallite size of about 46 nm. Weak diffraction peaks related mainly to cerium oxide were also detected at higher concentrations of Ce{sup 3+} (x=5–10 mol%). The scanning electron microscopy study revealed that the nanopowder samples were assembled in flower-shaped undoped ZnO and pyramid-shaped Ce{sup 3+}-doped ZnO nanostructures. The UV–vis spectra showed that the absorption edges shifted slightly to the longer wavelengths with the increase in the Ce{sup 3+} ions concentration. Moreover, the photoluminescence (PL) results showed a relative weak visible emission for the Ce{sup 3+}-doped ZnO nanoparticles compared to the undoped ZnO. The effects of Ce{sup 3+}-doping on the structure and PL of ZnO nanopowders are discussed in detail.

Fabrication of ZnO nanorod using spray-pyrolysis and chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Ramadhani, Muhammad F., E-mail: brian@tf.itb.ac.id; Pasaribu, Maruli A. H., E-mail: brian@tf.itb.ac.id; Yuliarto, Brian, E-mail: brian@tf.itb.ac.id; Nugraha, E-mail: brian@tf.itb.ac.id [Advanced Functional Materials Laboratory, Engineering Physics Department Faculty of Industrial Technology, Institut Teknologi Bandung (Indonesia)

2014-02-24

ZnO thin films with nanorod structure were deposited using Ultrasonic Spray Pyrolysis method for seed growth, and Chemical Bath Deposition (CBD) for nanorod growth. High purity Zn-hydrate and Urea are used to control Ph were dissolved in ethanol and aqua bidest in Ultrasonic Spray Pyrolysis process. Glass substrate was placed above the heater plate of reaction chamber, and subsequently sprayed with the range duration of 5, 10 and 20 minutes at the temperatures of 3500 C. As for the Chemical Bath Deposition, the glass substrate with ZnO seed on the surface was immerse to Zn-hydrate, HMTA (Hexa Methylene Tetra Amine) and deionized water solution for duration of 3, 5 and 7 hour and temperatures of 600 C, washed in distilled water, dried, and annealed at 3500 C for an hour. The characterization of samples was carried out to reveal the surface morphology using Scanning Electron Microscopy (SEM). From the data, the combination of 5 minutes of Ultrasonic Spray Pyrolysis process and 3 hour of CBD has showed the best structure of nanorod. Meanwhile the longer Spraying process and CBD yield the bigger nanorod structure that have been made, and it makes the films more dense which make the nanorod collide each other and as a result produce unsymetric nanorod structure.

Defect dynamics in Li substituted nanocrystalline ZnO: A spectroscopic analysis

Energy Technology Data Exchange (ETDEWEB)

Ghosh, S., E-mail: sghoshphysics@gmail.com [Department of Material Science, Indian Association for the Cultivation of Science, 2A and 2B Raja S.C. Mullick Road, Jadavpur, Kolkata 700032 (India); Nambissan, P.M.G.; Thapa, S. [Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, Sector 1, Block AF, Bidhannagar, Kolkata 700064 (India); Mandal, K. [Department of Condensed Matter Physics and Material Sciences, S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India)

2014-12-01

Very recently, vacancy-type defects have been found to play a major role in stabilizing d{sup 0} ferromagnetism in various low dimensional ZnO systems. In this context, the evolution of vacancy-type defects within the ZnO nanocrystals due to the doping of ZnO by alkali metal lithium (Li) is investigated using X-ray photoelectron (XPS), photoluminescence (PL) and positron annihilation spectroscopy (PAS). Li-doping is found to have significant effects in modifying the vacancy-type defects, especially the Zn vacancy (V{sub Zn}) defects within the ZnO lattice. XPS measurement indicated that initially the Li{sup 1+} ions substitute at Zn{sup 2+} sites, but when Li concentration exceeds 7 at%, excess Li starts to move through the interstitial sites. The increase in positron lifetime components and the lineshape S-parameter obtained from coincident Doppler broadening spectra with Li-doping indicated an enhancement of V{sub Zn} defect concentration within the doped ZnO lattice. The vacancy type defects, initially of the predominant configuration V{sub Zn+O+Zn} got reduced to neutral ZnO divacancies due to the partial recombination by the doped Li{sup 1+} ions but, when the doping concentration exceeded 7 at% and Li{sup 1+} ions started migrating to the interstitials, positron diffusion is partly impeded and this results in reduced probability of annihilation. PL spectra have shown intense green and yellow-orange emission due to the stabilization of a large number of V{sub Zn} defects and Li substitutional (Li{sub Zn}) defects respectively. Hence Li can be a very useful dopant in stabilizing and modifying significant amount of Zn vacancy-defects which can play a useful role in determining the material behavior.

Thermal conductivity and nanocrystalline structure of platinum deposited by focused ion beam

KAUST Repository

Alaie, Seyedhamidreza

2015-02-04

Pt deposited by focused ion beam (FIB) is a common material used for attachment of nanosamples, repair of integrated circuits, and synthesis of nanostructures. Despite its common use little information is available on its thermal properties. In this work, Pt deposited by FIB is characterized thermally, structurally, and chemically. Its thermal conductivity is found to be substantially lower than the bulk value of Pt, 7.2 W m-1 K-1 versus 71.6 W m-1 K-1 at room temperature. The low thermal conductivity is attributed to the nanostructure of the material and its chemical composition. Pt deposited by FIB is shown, via aberration corrected TEM, to be a segregated mix of nanocrystalline Pt and amorphous C with Ga and O impurities. Ga impurities mainly reside in the Pt while O is homogeneously distributed throughout. The Ga impurity, small grain size of the Pt, and the amorphous carbon between grains are the cause for the low thermal conductivity of this material. Since Pt deposited by FIB is a common material for affixing samples, this information can be used to assess systematic errors in thermal characterization of different nanosamples. This application is also demonstrated by thermal characterization of two carbon nanofibers and a correction using the reported thermal properties of the Pt deposited by FIB.

The electrical properties of low pressure chemical vapor deposition Ga doped ZnO thin films depending on chemical bonding configuration

Energy Technology Data Exchange (ETDEWEB)

Jung, Hanearl [School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Kim, Doyoung [School of Electrical and Electronic Engineering, Ulsan College, 57 Daehak-ro, Nam-gu, Ulsan 680-749 (Korea, Republic of); Kim, Hyungjun, E-mail: hyungjun@yonsei.ac.kr [School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

2014-04-01

Highlights: • Undoped and Ga doped ZnO thin films were deposited using DEZ and TMGa. • Effects of Ga doping using TMGa in Ga doped ZnO were investigated. • Degraded properties from excessive doping were analyzed using chemical bondings. - Abstract: The electrical and chemical properties of low pressure chemical vapor deposition (LP-CVD) Ga doped ZnO (ZnO:Ga) films were systematically investigated using Hall measurement and X-ray photoemission spectroscopy (XPS). Diethylzinc (DEZ) and O{sub 2} gas were used as precursor and reactant gas, respectively, and trimethyl gallium (TMGa) was used as a Ga doping source. Initially, the electrical properties of undoped LP-CVD ZnO films depending on the partial pressure of DEZ and O{sub 2} ratio were investigated using X-ray diffraction (XRD) by changing partial pressure of DEZ from 40 to 140 mTorr and that of O{sub 2} from 40 to 80 mTorr. The resistivity was reduced by Ga doping from 7.24 × 10{sup −3} Ω cm for undoped ZnO to 2.05 × 10{sup −3} Ω cm for Ga doped ZnO at the TMG pressure of 8 mTorr. The change of electric properties of Ga doped ZnO with varying the amount of Ga dopants was systematically discussed based on the structural crystallinity and chemical bonding configuration, analyzed by XRD and XPS, respectively.

Sonicated sol–gel preparation of nanoparticulate ZnO thin films with various deposition speeds: The highly preferred c-axis (0 0 2) orientation enhances the final properties

International Nuclear Information System (INIS)

Malek, M.F.; Mamat, M.H.; Khusaimi, Z.; Sahdan, M.Z.; Musa, M.Z.; Zainun, A.R.; Suriani, A.B.; Md Sin, N.D.; Abd Hamid, S.B.; Rusop, M.

2014-01-01

Highlights: • Minimum stress of highly c-axis oriented ZnO was grown at suitable deposition speed. • The ZnO crystal orientation was influenced by strain/stress of the film. • Minimum stress/strain of ZnO film leads to lower defects. • Bandgap and defects were closely intertwined with strain/stress. • We report additional optical and electrical properties based on deposition speed. -- Abstract: Zinc oxide (ZnO) thin films have been deposited onto glass substrates at various deposition speeds by a sonicated sol–gel dip-coating technique. This work studies the effects of deposition speed on the crystallisation behaviour and optical and electrical properties of the resulting films. X-ray diffraction (XRD) analysis showed that thin films were preferentially oriented along the (0 0 2) c-axis direction of the crystal. The transformation sequence of strain and stress effects in ZnO thin films has also been studied. The films deposited at a low deposition speed exhibited a large compressive stress of 0.78 GPa, which decreased to 0.43 GPa as the deposition speed increased to 40 mm/min. Interestingly, the enhancement in the crystallinity of these films led to a significant reduction in compressive stress. All films exhibited an average transmittance of greater than 90% in the visible region, with absorption edges at ∼380 nm. The photoluminescence (PL) measurements indicated that the intensity of the emission peaks varied significantly with deposition speed. The optical band gap energy (E g ) was evaluated as 3.276–3.289 eV, which increased with decreasing compressive stress along the c-axis. The energy band gap of the resulting ZnO films was found to be strongly influenced by the preferred c-axis (0 0 2) orientation

Preparation and characterization of nanocrystalline ITO thin films on glass and clay substrates by ion-beam sputter deposition method

International Nuclear Information System (INIS)

Venkatachalam, S.; Nanjo, H.; Kawasaki, K.; Wakui, Y.; Hayashi, H.; Ebina, T.

2011-01-01

Nanocrystalline indium tin oxide (ITO) thin films were prepared on clay-1 (Clay-TPP-LP-SA), clay-2 (Clay-TPP-SA) and glass substrates using ion-beam sputter deposition method. X-ray diffraction (XRD) patterns showed that the as-deposited ITO films on both clay-1 and clay-2 substrates were a mixture of amorphous and polycrystalline. But the as-deposited ITO films on glass substrates were polycrystalline. The surface morphologies of as-deposited ITO/glass has smooth surface; in contrast, ITO/clay-1 has rough surface. The surface roughnesses of ITO thin films on glass and clay-1 substrate were calculated as 4.3 and 83 nm, respectively. From the AFM and SEM analyses, the particle sizes of nanocrystalline ITO for a film thickness of 712 nm were calculated as 19.5 and 20 nm, respectively. Optical study showed that the optical transmittance of ITO/clay-2 was higher than that of ITO/clay-1. The sheet resistances of as-deposited ITO/clay-1 and ITO/clay-2 were calculated as 76.0 and 63.0 Ω/□, respectively. The figure of merit value for as-deposited ITO/clay-2 (12.70 x 10 -3 /Ω) was also higher than that of ITO/clay-1 (9.6 x 10 -3 /Ω), respectively. The flexibilities of ITO/clay-1 and ITO/clay-2 were evaluated as 13 and 12 mm, respectively. However, the ITO-coated clay-2 substrate showed much better optical and electrical properties as well as flexibility as compared to clay-1.

Microstructural, chemical and textural characterization of ZnO nanorods synthesized by aerosol assisted chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Fuentes-Cobas, L.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C. [Centro de Investigación en Materiales Avanzados, S.C., Chihuahua, Chihuahua 31109 (Mexico); Pérez-García, S.A. [Centro de Investigación en Materiales Avanzados, S.C., Unidad Monterrey, Apodaca, Nuevo León 66600 (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, S.C., Chihuahua, Chihuahua 31109 (Mexico)

2014-12-15

ZnO nanorods were synthesized by aerosol assisted chemical vapor deposition onto TiO{sub 2} covered borosilicate glass substrates. Deposition parameters were optimized and kept constant. Solely the effect of different nozzle velocities on the growth of ZnO nanorods was evaluated in order to develop a dense and uniform structure. The crystalline structure was characterized by conventional X-ray diffraction in grazing incidence and Bragg–Brentano configurations. In addition, two-dimensional grazing incidence synchrotron radiation diffraction was employed to determine the preferred growth direction of the nanorods. Morphology and growth characteristics analyzed by electron microscopy were correlated with diffraction outcomes. Chemical composition was established by X-ray photoelectron spectroscopy. X-ray diffraction results and X-ray photoelectron spectroscopy showed the presence of wurtzite ZnO and anatase TiO{sub 2} phases. Morphological changes noticed when the deposition velocity was lowered to the minimum, indicated the formation of relatively vertically oriented nanorods evenly distributed onto the TiO{sub 2} buffer film. By coupling two-dimensional X-ray diffraction and computational modeling with ANAELU it was proved that a successful texture determination was achieved and confirmed by scanning electron microscopy analysis. Texture analysis led to the conclusion of a preferred growth direction in [001] having a distribution width Ω = 20° ± 2°. - Highlights: • Uniform and pure single-crystal ZnO nanorods were obtained by AACVD technique. • Longitudinal and transversal axis parallel to the [001] and [110] directions, respectively. • Texture was determined by 2D synchrotron diffraction and electron microscopy analysis. • Nanorods have its [001] direction distributed close to the normal of the substrate. • Angular spread about the preferred orientation is 20° ± 2°.

High-pressure condition of SiH{sub 4}+Ar+H{sub 2} plasma for deposition of hydrogenated nanocrystalline silicon film

Energy Technology Data Exchange (ETDEWEB)

Parashar, A.; Kumar, Sushil; Dixit, P.N.; Gope, Jhuma; Rauthan, C.M.S. [Plasma Processed Materials Group, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Hashmi, S.A. [Department of Physics and Astro Physics, University of Delhi, Delhi 110007 (India)

2008-10-15

The characteristics of 13.56-MHz discharged SiH{sub 4}+Ar+H{sub 2} plasma at high pressure (2-8 Torr), used for the deposition of hydrogenated nanocrystalline silicon (nc-Si:H) films in a capacitively coupled symmetric PECVD system, has been investigated. Plasma parameters such as average electron density, sheath field and bulk field are extracted from equivalent circuit model of the plasma using outputs (current, voltage and phase) of RF V-I probe under different pressure conditions. The conditions of growth in terms of plasma parameters are correlated with properties of the hydrogenated nanocrystalline silicon films characterized by Raman, AFM and dc conductivity. The film deposited at 4 Torr of pressure, where relatively low sheath/bulk field ratio is observed, exhibits high crystallinity and conductivity. The crystalline volume fraction of the films estimated from the Raman spectra is found to vary from 23% to 79%, and the trend of variation is similar to the RF real plasma impedance data. (author)

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

Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

Energy Technology Data Exchange (ETDEWEB)

Singh, Ajaib [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Schipmann, Susanne [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Mathur, Aakash; Pal, Dipayan [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Sengupta, Amartya [Department of Physics, Indian Institute of Technology Delhi, Delhi 110016 (India); Klemradt, Uwe [II. Insatitute of Physics and JARA-FIT, RWTH Aachen University, 52056 Aachen (Germany); Chattopadhyay, Sudeshna, E-mail: sudeshna@iiti.ac.in [Discipline of Metallurgy Engineering and Materials Science, Indian Institute of Technology Indore, Indore 453552 (India); Discipline of Physics, Indian Institute of Technology Indore, Indore 453552 (India); Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore 453552 (India)

2017-08-31

Highlights: • Ultra-thin ZnO films grown on confined polymeric (polystyrene, PS) template. • XRR and GISAXS explore the surface/interfaces structure and morphology of ZnO/PS. • Insights into the growth mechanism of magnetron sputtered ZnO thin film on PS template. • Nucleated disk-like cylindrical particles are the basis of the formation of ZnO layers. • Effect of ZnO film thickness on room temperature PL spectra in ZnO/PS systems. - Abstract: The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2R{sub g} film thickness, where R{sub g} ∼ 20 nm (R{sub g} is the unperturbed radius of gyration of polystyrene, defined by R{sub g} = 0.272 √M{sub 0}, and M{sub 0} is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2–7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

Temperature dependent dual hydrogen sensor response of Pd nanoparticle decorated Al doped ZnO surfaces

Energy Technology Data Exchange (ETDEWEB)

Gupta, D.; Barman, P. B.; Hazra, S. K., E-mail: surajithazra@yahoo.co.in [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh-173234 (India); Dutta, D. [IC Design and Fabrication Centre, Department of Electronics and Telecommunication Engineering, Jadavpur University, Kolkata-700032 (India); Kumar, M.; Som, T. [SUNAG Laboratory, Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

2015-10-28

Sputter deposited Al doped ZnO (AZO) thin films exhibit a dual hydrogen sensing response in the temperature range 40 °C–150 °C after surface modifications with palladium nanoparticles. The unmodified AZO films showed no response in hydrogen in the temperature range 40 °C–150 °C. The operational temperature windows on the low and high temperature sides have been estimated by isolating the semiconductor-to-metal transition temperature zone of the sensor device. The gas response pattern was modeled by considering various adsorption isotherms, which revealed the dominance of heterogeneous adsorption characteristics. The Arrhenius adsorption barrier showed dual variation with change in hydrogen gas concentration on either side of the semiconductor-to-metal transition. A detailed analysis of the hydrogen gas response pattern by considering the changes in nano palladium due to hydrogen adsorption, and semiconductor-to-metal transition of nanocrystalline Al doped ZnO layer due to temperature, along with material characterization studies by glancing incidence X-ray diffraction, atomic force microscopy, and transmission electron microscopy, are presented.

Chemical Bath Deposition of PbS:Hg2+ Nanocrystalline Thin Films

Directory of Open Access Journals (Sweden)

R. Palomino-Merino

2013-01-01

Full Text Available Nanocrystalline PbS thin films were prepared by Chemical Bath Deposition (CBD at 40 ± 2°C onto glass substrates and their structural and optical properties modified by in-situ doping with Hg. The morphological changes of the layers were analyzed using SEM and the X-rays spectra showing growth on the zinc blende (ZB face. The grain size determined by using X-rays spectra for undoped samples was found to be ~36 nm, whereas with the doped sample was 32–20 nm. Optical absorption spectra were used to calculate the Eg, showing a shift in the range 1.4–2.4 eV. Raman spectroscopy exhibited an absorption band ~135 cm−1 displaying only a PbS ZB structure.

Parametric study of self-forming ZnO Nanowall network with honeycomb structure by Pulsed Laser Deposition

KAUST Repository

El Zein, B.; Boulfrad, Samir; Jabbour, Ghassan E.; Doghè che, Elhadj Hadj

2014-01-01

The successful synthesis of catalyst free zinc oxide (ZnO) Nanowall networks with honeycomb like structure by Pulsed Laser Deposition (PLD) is demonstrated in this paper. The synthesis was conducted directly on Silicon (Si) (1 0 0) and Glass

A study of the effects of aligned vertically growth time on ZnO nanorods deposited for the first time on Teflon substrate

Science.gov (United States)

Farhat, O. F.; Halim, M. M.; Ahmed, Naser M.; Oglat, Ammar A.; Abuelsamen, A. A.; Bououdina, M.; Qaeed, M. A.

2017-12-01

In this study, ZnO nanorods (NRs) were well deposited on Teflon substrates (PTFE) via a chemical bath deposition (CBD) method at low temperature. The consequences of growth time (1 h-4 h) on the structural and optical properties of the aligned ZnO (NRs) were investigated through X-ray diffraction, field-emission scanning electron microscopy (FESEM), and photoluminescence (PL) analyses. The results show that the ZnO (NRs) were preferred to grew aligned along the c-axis as hexagonal wurtzite structure as proved by the sharp and strong ZnO (002) peaks of the ZnO (NRs). Irrespective of the growth continuation, FESEM photos confirmed that the ZnO nanorods arrays were fit to be aligned along the c-axis and perpendicular to (PTFE) substrates. The ZnO nanorods that exhibited the sharper stand most intense PL peaks among the sample were grown for 3hs as demonstrated by PL spectra. The device further showed a sensitivity of 4068 to low-power (1.25 mW/cm2) 375 nm light pulses without an external bias. The measurements of photoresponse demonstrated the highly reproducible characteristics of the fabricated UV detector with rapid response and baseline recovery times of 48.05 ms. Thus, this work introduced a simple, low-cost method of fabricating rapid-response, and highly photosensitive UV detectors with zero power consumption on Teflon substrates.

Defects and the optical absorption in nanocrystalline ZnO

International Nuclear Information System (INIS)

Dutta, Sreetama; Chattopadhyay, Sanjay; Sutradhar, Manas; Sarkar, Anindya; Chakrabarti, Mahuya; Sanyal, Dirtha; Jana, Debnarayan

2007-01-01

The correlation between the structural and optical properties of mechanically milled high purity ZnO powder is reported in the present work. Reduction of average grain size and enhancement of strain as a result of milling have been estimated from the broadening of x-ray powder diffraction patterns. After milling, the optical bandgap, revealed from absorption spectroscopy, has been red-shifted and the width of the localized states, calculated from the analysis of the Urbach tail below the absorption edge, has been extended more and more into the bandgap. Moreover, the band tailing parameter is seen to vary exponentially with the inverse of the grain size. Finally, the positron annihilation technique has been employed to identify the nature of defects present (or generated due to milling) in the system and thereby to correlate the defect mediated modification of optical absorption in ZnO

Defects and the optical absorption in nanocrystalline ZnO

Energy Technology Data Exchange (ETDEWEB)

Dutta, Sreetama [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Chattopadhyay, Sanjay [Department of Physics, Taki Government College, Taki 743429 (India); Sutradhar, Manas [Department of Chemistry, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Sarkar, Anindya [Department of Physics, Bangabasi Morning College, 19 Rajkumar Chakraborty Sarani, Kolkata 700 009 (India); Chakrabarti, Mahuya [Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata 700 064 (India); Sanyal, Dirtha [Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata 700 064 (India); Jana, Debnarayan [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India)

2007-06-13

The correlation between the structural and optical properties of mechanically milled high purity ZnO powder is reported in the present work. Reduction of average grain size and enhancement of strain as a result of milling have been estimated from the broadening of x-ray powder diffraction patterns. After milling, the optical bandgap, revealed from absorption spectroscopy, has been red-shifted and the width of the localized states, calculated from the analysis of the Urbach tail below the absorption edge, has been extended more and more into the bandgap. Moreover, the band tailing parameter is seen to vary exponentially with the inverse of the grain size. Finally, the positron annihilation technique has been employed to identify the nature of defects present (or generated due to milling) in the system and thereby to correlate the defect mediated modification of optical absorption in ZnO.

The effect of different molarities of precursor Zn(NO3)2.6H2O to the growth of ZnO by solution-immersion deposited on ZnO seeded template

International Nuclear Information System (INIS)

Afaah, A N; Asib, N A M; Aadila, A; Eswar, K A; Mahmud, M R; Khusaimi, Z; Alrokayan, Salman A H; Khan, Haseeb A; Mohamed, R; Rusop, M

2015-01-01

ZnO films were grown on glass substrates by mist-atomization, with the growth temperature of 300 °C to form ZnO seeded template. The ZnO seeded template then undergo second deposition method, which is solution-immersion method to grow ZnO on the ZnO seeded template thin film. The thin films were immersed in different molarities of starting materials; which are zinc nitrate hexahydrate and HMTA. The molarities were varied from 0.05, 0.10, 0.20 and 0.40 M. As a control to the study, the ZnO seeded template which undergoes mist-atomization only, denoted as MA only is prepared for comparison studies to the other samples. The properties of the products were examined by photoluminescence (PL) spectrophotometer, Raman spectrophotometer, and ultraviolet-visible (UV-Vis) spectrophotometer. From the PL measurement, it shows that 0.40 M sample have highest UV emission and from Raman measurements, it was found that the sample immersed in 0.40 M precursor have high crystal quality. From UV-Vis measurements, sharp UV emission at ∼378 nm is observed and 0.40 M ZnO thin film shows a better absorption properties. (paper)

An Optoelectronic Sensor Configuration Using ZnO Thick Film for Detection of Methanol

Directory of Open Access Journals (Sweden)

Shobhna DIXIT

2007-08-01

Full Text Available In the present paper sensitivity of a nanocrystalline ZnO thick film to methanol vapors is reported. The sensing mechanism is the modulation in the intensity of light reflected from glass film interface. Modulation occurs due to the change in refractive index of ZnO film upon adsorption of vapor molecules. The film has been characterized by XRD, SEM, and optical transmission studies. XRD pattern reveals polycrystalline structure of the film with grain size 33.5 nm.

Negative permittivity of ZnO thin films prepared from aluminum and gallium doped ceramics via pulsed-laser deposition

DEFF Research Database (Denmark)

Bodea, M. A.; Sbarcea, G.; Naik, G. V.

2013-01-01

Aluminum and gallium doped zinc oxide thin films with negative dielectric permittivity in the near infrared spectral range are grown by pulsed laser deposition. Composite ceramics comprising ZnO and secondary phase Al2O3 or Ga2O3 are employed as targets for laser ablation. Films deposited on glass...

Metalorganic chemical vapor deposition and characterization of ZnO materials

Science.gov (United States)

Sun, Shangzu; Tompa, Gary S.; Hoerman, Brent; Look, David C.; Claflin, Bruce B.; Rice, Catherine E.; Masaun, Puneet

2006-04-01

Zinc oxide is attracting growing interest for potential applications in electronics, optoelectronics, photonics, and chemical and biochemical sensing, among other applications. We report herein our efforts in the growth and characterization of p- and n-type ZnO materials by metalorganic chemical vapor deposition (MOCVD), focusing on recent nitrogen-doped films grown using diethyl zinc as the zinc precursor and nitric oxide (NO) as the dopant. Characterization results, including resistivity, Hall measurements, photoluminescence, and SIMS, are reported and discussed. Electrical behavior was observed to be dependent on illumination, atmosphere, and heat treatment, especially for p-type material.

Role of chlorine in the nanocrystalline silicon film formation by rf plasma-enhanced chemical vapor deposition of chlorinated materials

International Nuclear Information System (INIS)

Shirai, Hajime

2004-01-01

We demonstrate the disorder-induced low-temperature crystallization in the nanocrystalline silicon film growth by rf plasma-enhanced chemical vapor deposition of H 2 -diluted SiH 2 Cl 2 and SiCl 4 . The combination of the chemical reactivity of SiCld (d: dangling bond) and SiHCl complexes and the release of the disorder-induced stress near the growing surface tightly correlate with the phase transitionity of SiCld and SiHCl complexes near the growing surface with the aid of atomic hydrogen, which induce higher degree of disorder in the a-Si network. These features are most prominent in the SiCl 4 compared with those of SiH 2 Cl 2 and SiH 4 , which preferentially enhance the nanocrystalline Si formation

Texture-dependent twin formation in nanocrystalline thin Pd films

International Nuclear Information System (INIS)

Wang, B.; Idrissi, H.; Shi, H.; Colla, M.S.; Michotte, S.; Raskin, J.P.; Pardoen, T.; Schryvers, D.

2012-01-01

Nanocrystalline Pd films were produced by electron-beam evaporation and sputter deposition. The electron-beam-evaporated films reveal randomly oriented nanograins with a relatively high density of growth twins, unexpected in view of the high stacking fault energy of Pd. In contrast, sputter-deposited films show a clear 〈1 1 1〉 crystallographic textured nanostructure without twins. These results provide insightful information to guide the generation of microstructures with enhanced strength/ductility balance in high stacking fault energy nanocrystalline metallic thin films.

Preparation of nanocrystalline Ni doped ZnS thin films by ammonia-free chemical bath deposition method and optical properties

Energy Technology Data Exchange (ETDEWEB)

Sahraei, Reza, E-mail: r.sahraei@ilam.ac.ir; Darafarin, Soraya

2014-05-01

Nanocrystalline Ni doped ZnS thin films were deposited on quartz, silicon, and glass substrates using chemical bath deposition method in a weak acidic solution containing ethylenediamine tetra acetic acid disodium salt (Na{sub 2}EDTA) as a complexing agent for zinc ions and thioacetamide (TAA) as a sulfide source at 80 °C. The films were characterized by energy-dispersive X-ray spectrometer (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform-infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible spectrophotometry, and photoluminescence (PL) spectroscopy. UV–vis transmission data showed that the films were transparent in the visible region. The X-ray diffraction analysis showed a cubic zinc blend structure. FE-SEM revealed a homogeneous morphology and dense nanostructures. The PL spectra of the ZnS:Ni films showed two characteristic bands, one broad band centered at 430 and another narrow band at 523 nm. Furthermore, concentration quenching effect on the photoluminescence intensity has been observed. - Highlights: • Nanocrystalline ZnS:Ni thin films were prepared by the chemical bath deposition method. • The size of ZnS:Ni nanocrystals was less than 10 nm showing quantum size effect. • SEM images demonstrated a dense and uniform surface that was free of pinholes. • The deposited films were highly transparent (>70%) in the visible region. • The PL spectra of ZnS:Ni thin films showed two emission peaks at 430 and 523 nm.

Pulsed laser deposited Al-doped ZnO thin films for optical applications

Directory of Open Access Journals (Sweden)

Gurpreet Kaur

2015-02-01

Full Text Available Highly transparent and conducting Al-doped ZnO (Al:ZnO thin films were grown on glass substrates using pulsed laser deposition technique. The profound effect of film thickness on the structural, optical and electrical properties of Al:ZnO thin films was observed. The X-ray diffraction depicts c-axis, plane (002 oriented thin films with hexagonal wurtzite crystal structure. Al-doping in ZnO introduces a compressive stress in the films which increase with the film thickness. AFM images reveal the columnar grain formation with low surface roughness. The versatile optical properties of Al:ZnO thin films are important for applications such as transparent electromagnetic interference (EMI shielding materials and solar cells. The obtained optical band gap (3.2–3.08 eV was found to be less than pure ZnO (3.37 eV films. The lowering in the band gap in Al:ZnO thin films could be attributed to band edge bending phenomena. The photoluminescence spectra gives sharp visible emission peaks, enables Al:ZnO thin films for light emitting devices (LEDs applications. The current–voltage (I–V measurements show the ohmic behavior of the films with resistivity (ρ~10−3 Ω cm.

Study of nanocluster-assembled ZnO thin films by nanocluster-beam deposition

Energy Technology Data Exchange (ETDEWEB)

Zhao, Zhiwei; Lei, Wei; Zhang, Xiaobing [School of Electronic Science and Engieering, Southeast University, Nanjing (China); Tay, Beng Kang [School of Electronical and Electronic Engineering, Nanyang Technological University, Nanyang (Singapore)

2012-01-15

Nanocluster-assembled ZnO thin films were obtained by nanocluster-beam deposition, in which nanoclusters were produced by a magnetron sputtering gas aggregation source. Two kinds of ZnO thin films were obtained using this method with the one grown under the on-line heating temperature of 700 C, and the other grown without on-line heating. Film microstructure and optical properties are investigated by various diagnostic techniques. It was found that both of film microstructure of ZnO thin films keep wurtzite structure as that of ZnO bulk materials. The averaged particle size for the film grown without on-line heating is around 6 nm, which is a little lower than that grown with the on-line heating. It was also found that as increasing the wavelength, both of the absorbance spectra for the films decrease sharply near ultra-visible to extend slowly to the visible and infrared wavelength range. For the film grown without on-line heating, the bandgap energy was estimated to 3.77 eV, while for the film grown with on-line heating, the bandgap energy was redshift to 3.71 eV. Similar behavior was also found for PL spectra analysis, where PL spectrum exhibited a peak centered at 3.31 eV without on-line heating, while it redshift to 3.20 eV with on-line heating. The mechanisms behind these behaviors were presented in this article. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Phase diagram of interfacial growth modes by vapor deposition and its application for ZnO nanostructures

Science.gov (United States)

Shu, Da-Jun; Xiong, Xiang; Liu, Ming; Wang, Mu

2017-09-01

Interfacial growth from vapor has been extensively studied. However, a straightforward picture of the growth mode under different growth conditions is still lacking. In this paper, we develop a comprehensive interfacial growth theory based on the stochastic approach. Using a critical interisland separation, we construct a general phase diagram of the growth modes. It has been revealed that if the Ehrlich-Schwoebel barrier EES is smaller than a critical value, the interfacial growth proceeds in a layer-by-layer (LBL) mode at any deposition rate. However, if EES is larger than the critical value, LBL growth occurs only at very small or very large deposition rates relative to the intralayer hopping rate, and multilayer (ML) growth occurs at a moderate deposition rate. Experiments with zinc oxide growth by chemical vapor deposition have been designed to qualitatively demonstrate the theoretical model. By changing the flux of the carrier gas (nitrogen gas) in chemical vapor deposition, we realize LBL, ML, and then reentrance of LBL homoepitaxial growth of ZnO successively. Moreover, we find that surface kinetics of ZnO is suppressed by decreasing oxygen partial pressure by comparing the experimental observations and theoretical models, which is supported by our recent first-principles calculations. Since the influence of the substrate and the growth species on growth can approximately be represented by binding energy and surface kinetics, we suggest that the phase diagram is essential for interfacial growth of different materials by vapor deposition.

Role of VI/II ratio on the growth of ZnO nanostructures using chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Urgessa, Z.N., E-mail: zelalem.urgessa@nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Oluwafemi, O.S. [Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag XI, 5117 (South Africa); Botha, J.R. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

2012-05-15

In this paper the growth process and morphological evolution of ZnO nanostructures were investigated in a series of experiments using chemical bath deposition. The experimental results indicate that the morphological evolution depends on the reaction conditions, particularly on OH{sup -} to Zn{sup 2+} ratio (which directly affects the pH). For low VI/II ratios, quasi-spherical nanoparticles of an average diameter 30 nm are obtained, whereas for larger VI/II ratios, nanorods with an average diameter less than 100 nm are produced, which indicates that by systematically controlling the VI/II ratio, it is possible to produce different shapes and sizes of ZnO nanostructures. A possible mechanism for the nanostructural change of the as-synthesized ZnO from particle to rod was elucidated based on the relative densities of H{sup +} and OH{sup -} in the solution.

Role of VI/II ratio on the growth of ZnO nanostructures using chemical bath deposition

International Nuclear Information System (INIS)

Urgessa, Z.N.; Oluwafemi, O.S.; Botha, J.R.

2012-01-01

In this paper the growth process and morphological evolution of ZnO nanostructures were investigated in a series of experiments using chemical bath deposition. The experimental results indicate that the morphological evolution depends on the reaction conditions, particularly on OH − to Zn 2+ ratio (which directly affects the pH). For low VI/II ratios, quasi-spherical nanoparticles of an average diameter 30 nm are obtained, whereas for larger VI/II ratios, nanorods with an average diameter less than 100 nm are produced, which indicates that by systematically controlling the VI/II ratio, it is possible to produce different shapes and sizes of ZnO nanostructures. A possible mechanism for the nanostructural change of the as-synthesized ZnO from particle to rod was elucidated based on the relative densities of H + and OH − in the solution.

Gum Tragacanth-Mediated Synthesis of Nanocrystalline ZnO Powder for Use in Varistors

Science.gov (United States)

Liu, Ting-Ting; Wang, Mao-Hua; Su, Hang; Chen, Xi; Chen, Chao; Zhang, Ruo-Chen

2015-10-01

Zinc oxide nanopowders were synthesized by a sol-gel method with gum tragacanth and zinc nitrate as raw materials. Gum tragacanth was used as stabilizer to control the mobility of zinc cations and the growth of the nanopowders. Thermo-gravimetric analysis, x-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, and scanning electron microscopy were used to characterize the as-prepared samples. Zinc oxide (ZnO) nanoparticles calcined at different temperatures had a hexagonal wurtzite structure with average particle size ranging from 32.29 nm to 42.83 nm. The crystallinity of ZnO nanoparticles was improved by increasing the calcination temperature. The density of ZnO varistor ceramics sintered at 1150°C for 2 h in air was 5.46 g/cm3, which was 97.5% of the theoretical density, their breakdown voltage was 4572 V/cm, and their nonlinear coefficient was ~16.8. This method can be used as an excellent alternative method for synthesis of ZnO nanoparticles with a plant extract as a raw material. Our experimental results show our method had the advantage of improving the electrical performance of ZnO varistors.

Microstructures and photocatalytic properties of porous ZnO films synthesized by chemical bath deposition method

International Nuclear Information System (INIS)

Wang Huihu; Dong, Shijie; Chang Ying; Zhou Xiaoping; Hu Xinbin

2012-01-01

Different porous ZnO film structures on the surface of alumina substrates were prepared through a simple chemical bath deposition method in the methanolic zinc acetate solution. The surface morphology and phase structure of porous ZnO film were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Both initial zinc acetate concentration and sintering temperature have great impact on the final film structures. With the increase of initial zinc acetate concentration, the porous structures can be finely tuned from circular nest like assemblies composed film into successive nest like film, and finally to globular aggregates composed film. By increasing the sintering temperature, the porous structure of successive nest like film can be further controlled. Furthermore, the crystallinity of photocatalysts also can be greatly improved. The photodegradation results of Methyl Orange revealed that porous ZnO film with successive nest like structure sintered at 500 °C exhibited the highest photocatalytic activity under UV illumination.

Effect of Annealing on the Structural and Optical Properties of Nano Fiber ZnO Films Deposited by Spray Pyrolysis

Directory of Open Access Journals (Sweden)

M. R. Islam

2011-11-01

Full Text Available Nano fiber ZnO films have been deposited on to glass substrate at 200 °C by a simple spray pyrolysis technique under atmospheric pressure. The effect of annealing temperature on the structural and optical properties of the as grown films has been studied by Scanning Electron Microscopy (SEM attached with an EDX, powder X-ray diffraction and UV visible spectroscopy. The atomic weight % of Zinc and Oxygen were found to be 49.22 % and 49.62 % respectively. The SEM micrographs show nano fiber structure and uniform deposition on the substrate. Average grain size of ZnO thin film was found in the range of 21 to 27 nm. The lattice constant a and c of ZnO thin film are determined at different annealing temperatures and values are found slightly larger than those of JCPDS data and lower for the sample annealed at 600 °C. The lattice parameters a and c decrease with increasing temperature. It reveals that the samples are poly-crystalline and having with low densities. Band gap energy of ZnO was found in the range of 3.33 to 3.17 eV and decreases with the increase of the annealing temperature.

Anti-microbial surfaces: An approach for deposition of ZnO nanoparticles on PVA-Gelatin composite film by screen printing technique

Energy Technology Data Exchange (ETDEWEB)

Meshram, J.V.; Koli, V.B.; Phadatare, M.R.; Pawar, S.H., E-mail: shpawar1946@gmail.com

2017-04-01

Initially micro-organisms get exposed to the surfaces, this demands development of anti-microbial surfaces to inhibit their proliferation. Therefore, herein, we attempt screen printing technique for development of PVA-GE/ZnO nanocomposite (PG/ZnO) films. The synthesis of PG/ZnO nanocomposite includes two steps as: (i) Coating of Zinc Oxide nanoparticles (ZnO NPs) by poly ethylene glycol in order to be compatible with organic counterparts. (ii) Deposition of coated nanoparticles on the PG film surface. The results suggest the enhancement in anti-microbial activity of PG/ZnO nanocomposite over pure ZnO NPs against both Gram positive Bacillus subtilis and Gram negative Escherichia coli from zone of inhibition. The uniformity in deposition is further confirmed by scanning electron microscopy (SEM) images. The phase identification of ZnO NPs and formation of PG/ZnO nanocomposite has been confirmed by X-ray diffraction (XRD) analysis and UV–vis spectroscopy (UV–vis). The Attenuated total reflection Spectroscopy (ATR) analysis indicates the ester bond between PVA and gelatin molecules. The thermal stability of nanocomposite is studied by thermogravimetric analysis (TGA) revealing increase in crystallinity due to ZnO NPs which could be utilized to inhibit the growth of micro-organisms. The tensile strength is found to be higher and percent elongation is double of PG/ZnO nanocomposite than PG composite film. - Highlights: • Synthesis of PG/ZnO nanocomposite by screen printing technique • Antimicrobial activity is due presence of ZnO nanoparticles on PG composite. • Improved tensile strength due to ZnO nanoparticles.

Effect of deposition rate on the microstructure of electron beam evaporated nanocrystalline palladium thin films

Energy Technology Data Exchange (ETDEWEB)

Amin-Ahmadi, B., E-mail: behnam.amin-ahmadi@ua.ac.be [Electron Microscopy for Materials Science (EMAT), Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Idrissi, H. [Electron Microscopy for Materials Science (EMAT), Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Galceran, M. [Université Libre de Bruxelles, Matters and Materials Department, 50 Av. FD Roosevelt CP194/03, 1050 Brussels (Belgium); Colla, M.S. [Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, Place Sainte Barbe 2, B-1348 Louvain-la-Neuve (Belgium); Raskin, J.P. [Information and Communications Technologies, Electronics and Applied Mathematics (ICTEAM), Microwave Laboratory, Université catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Pardoen, T. [Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, Place Sainte Barbe 2, B-1348 Louvain-la-Neuve (Belgium); Godet, S. [Université Libre de Bruxelles, Matters and Materials Department, 50 Av. FD Roosevelt CP194/03, 1050 Brussels (Belgium); Schryvers, D. [Electron Microscopy for Materials Science (EMAT), Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

2013-07-31

The influence of the deposition rate on the formation of growth twins in nanocrystalline Pd films deposited by electron beam evaporation is investigated using transmission electron microscopy. Statistical measurements prove that twin boundary (TB) density and volume fraction of grains containing twins increase with increasing deposition rate. A clear increase of the dislocation density was observed for the highest deposition rate of 5 Å/s, caused by the increase of the internal stress building up during deposition. Based on crystallographic orientation indexation using transmission electron microscopy, it can be concluded that a {111} crystallographic texture increases with increasing deposition rate even though the {101} crystallographic texture remains dominant. Most of the TBs are fully coherent without any residual dislocations. However, for the highest deposition rate (5 Å/s), the coherency of the TBs decreases significantly as a result of the interaction of lattice dislocations emitted during deposition with the growth TBs. The analysis of the grain boundary character of different Pd films shows that an increasing fraction of high angle grain boundaries with misorientation angles around 55–65° leads to a higher potential for twin formation. - Highlights: • Fraction of twinned grains and twin boundary density increase with deposition rate. • Clear increase of dislocation density was observed for the highest deposition rate. • A moderate increase of the mean grain size with increase of deposition rate is found. • For the highest deposition rate, the twin boundaries lose their coherency. • Fraction of high angle grain boundary (55–65) increases with deposition rate.

Enhanced photocatalytic reduction of CO2 to methanol by ZnO nanoparticles deposited on ZnSe nanosheet

Science.gov (United States)

Zhang, Shuangfang; Yin, Xiaohong; Zheng, Yinan

2018-02-01

In this work ZnO/ZnSe composites were successfully synthesized via solvothermal method and characterized by a series of experiments for investigating into their compositions, morphologies, microstructures and the activities of photocatalytic reduction of CO2. The methanol rates of bare ZnO and ZnSe respectively were 763.9 μmol/gcat/h and 503.88 μmol/gcat/h. However, the sample of 3 wt% ZnO/ZnSe performed better photocatalytic activity up 1581.82 μmol/gcat/h compared to bare ZnO and ZnSe. In the as-prepared photocatalyst the nanosheet of ZnSe benefited the light harvest; suitable deposition of ZnO on the ZnSe nanosheet constructed a type II heterojunction for transferring the photo-generated electron to reduce CO2.

Two-step deposition of Al-doped ZnO on p-GaN to form ohmic contacts

Science.gov (United States)

Su, Xi; Zhang, Guozhen; Wang, Xiao; Chen, Chao; Wu, Hao; Liu, Chang

2017-07-01

Al-doped ZnO (AZO) thin films were deposited directly on p-GaN substrates by using a two-step deposition consisting of polymer assisted deposition (PAD) and atomic layer deposition (ALD) methods. Ohmic contacts of the AZO on p-GaN have been formed. The lowest sheet resistance of the two-step prepared AZO films reached to 145 Ω/sq, and the specific contact resistance reduced to 1.47 × 10-2 Ω·cm2. Transmittance of the AZO films remained above 80% in the visible region. The combination of PAD and ALD technique can be used to prepare p-type ohmic contacts for optoelectronics.

ZnO nanowall network grown by chemical vapor deposition technique

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, Amrita, E-mail: but.then.perhaps@gmail.com; Dhar, Subhabrata [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India)

2015-06-24

Network of wedge shaped ZnO nanowalls are grown on c-sapphire by Chemical Vapor Deposition (CVD) technique. Structural studies using x-ray diffraction show much better crystallinity in the nanowall sample as compared to the continuous film. Moreover, the defect related broad green luminescence is found to be suppressed in the nanowall sample. The low temperature photoluminescence study also suggests the quantum confinement of carriers in nanowall sample. Electrical studies performed on the nanowalls show higher conductivity, which has been explained in terms of the reduction of scattering cross-section as a result of 1D quantum confinement of carriers on the tip of the nanowalls.

Atomic Layer Deposition of Nickel on ZnO Nanowire Arrays for High-Performance Supercapacitors.

Science.gov (United States)

Ren, Qing-Hua; Zhang, Yan; Lu, Hong-Liang; Wang, Yong-Ping; Liu, Wen-Jun; Ji, Xin-Ming; Devi, Anjana; Jiang, An-Quan; Zhang, David Wei

2018-01-10

A novel hybrid core-shell structure of ZnO nanowires (NWs)/Ni as a pseudocapacitor electrode was successfully fabricated by atomic layer deposition of a nickel shell, and its capacitive performance was systemically investigated. Transmission electron microscopy and X-ray photoelectron spectroscopy results indicated that the NiO was formed at the interface between ZnO and Ni where the Ni was oxidized by ZnO during the ALD of the Ni layer. Electrochemical measurement results revealed that the Ti/ZnO NWs/Ni (1500 cycles) electrode with a 30 nm thick Ni-NiO shell layer had the best supercapacitor properties including ultrahigh specific capacitance (∼2440 F g -1 ), good rate capability (80.5%) under high current charge-discharge conditions, and a relatively better cycling stability (86.7% of the initial value remained after 750 cycles at 10 A g -1 ). These attractive capacitive behaviors are mainly attributed to the unique core-shell structure and the combined effect of ZnO NW arrays as short charge transfer pathways for ion diffusion and electron transfer as well as conductive Ni serving as channel for the fast electron transport to Ti substrate. This high-performance Ti/ZnO NWs/Ni hybrid structure is expected to be one of a promising electrodes for high-performance supercapacitor applications.

Influence of substrate temperature and Zn-precursors on atomic layer deposition of polycrystalline ZnO films on glass

International Nuclear Information System (INIS)

Makino, Hisao; Miyake, Aki; Yamada, Takahiro; Yamamoto, Naoki; Yamamoto, Tetsuya

2009-01-01

Influence of substrate temperature and Zn-precursors on growth rate, crystal structure, and electrical property of undoped ZnO thin films grown by atomic layer deposition (ALD) have been studied. Differences between dimethylzinc (DMeZn) and diethylzinc (DEtZn) used as Zn-precursors were examined. The ZnO films grown using DMeZn showed higher electrical resistivity compared to that grown using DEtZn. However, the higher resistivity in the case of DMeZn was owing to much amount of residual impurities incorporated during the ALD growth

Gasochromic response of nanocrystalline vanadium pentoxide films deposited from ethanol dispersions

International Nuclear Information System (INIS)

Rizzo, G.; Arena, A.; Bonavita, A.; Donato, N.; Neri, G.; Saitta, G.

2010-01-01

Vanadium pentoxide (V 2 O 5 ) nanocrystals having few tens nanometers average size, are obtained from ammonium metavanadate (NH 4 VO 3 ) in the presence of oleic acid, and treating the reaction product at 400 o C. Nanocrystalline films, deposited from stable ethanol suspensions of the V 2 O 5 nanopowder, adhere strongly to different kinds of substrates, without the need of any thermal post processing. At room temperature, the films are found to bleach when exposed to ammonia. Bleaching originates from the formation of ammonium metavandate, and is reversible, as after annealing in air at 350 o C, ammonium metavanadate converts back to V 2 O 5 . Formation of ammonium metavanadate, clearly evidenced by remarkable changes in infrared spectrum of V 2 O 5 films exposed to ammonia, is a valuable detection mechanism, promising in view of developing highly selective ammonia sensors operating at room temperature.

Nanocrystalline zinc oxide for the decontamination of sarin

Energy Technology Data Exchange (ETDEWEB)

Mahato, T.H. [Defense R and D Establishment, Jhansi Road, 474002, Gwalior, MP (India); Prasad, G.K., E-mail: gkprasad@lycos.com [Defense R and D Establishment, Jhansi Road, 474002, Gwalior, MP (India); Singh, Beer; Acharya, J.; Srivastava, A.R.; Vijayaraghavan, R. [Defense R and D Establishment, Jhansi Road, 474002, Gwalior, MP (India)

2009-06-15

Nanocrystalline zinc oxide materials were prepared by sol-gel method and were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry, nitrogen adsorption and infrared spectroscopy techniques. The data confirmed the formation of zinc oxide materials of zincite phase with an average crystallite size of {approx}55 nm. Obtained material was tested as destructive adsorbent for the decontamination of sarin and the reaction was followed by GC-NPD and GC-MS techniques. The reaction products were characterized by GC-MS and the data explored the role of hydrolysis reaction in the detoxification of sarin. Sarin was hydrolyzed to form surface bound non-toxic phosphonate on the surface of nano-zinc oxide. The data also revealed the values of rate constant and half-life to be 4.12 h{sup -1} and 0.16 h in the initial stages of the reaction and 0.361 h{sup -1} and 1.9 h at the final stages of the reaction for the decontamination reaction on nanocrystalline ZnO.

Nanocrystalline zinc oxide for the decontamination of sarin

International Nuclear Information System (INIS)

Mahato, T.H.; Prasad, G.K.; Singh, Beer; Acharya, J.; Srivastava, A.R.; Vijayaraghavan, R.

2009-01-01

Nanocrystalline zinc oxide materials were prepared by sol-gel method and were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry, nitrogen adsorption and infrared spectroscopy techniques. The data confirmed the formation of zinc oxide materials of zincite phase with an average crystallite size of ∼55 nm. Obtained material was tested as destructive adsorbent for the decontamination of sarin and the reaction was followed by GC-NPD and GC-MS techniques. The reaction products were characterized by GC-MS and the data explored the role of hydrolysis reaction in the detoxification of sarin. Sarin was hydrolyzed to form surface bound non-toxic phosphonate on the surface of nano-zinc oxide. The data also revealed the values of rate constant and half-life to be 4.12 h -1 and 0.16 h in the initial stages of the reaction and 0.361 h -1 and 1.9 h at the final stages of the reaction for the decontamination reaction on nanocrystalline ZnO.

Fabrication and photovoltaic properties of ZnO nanorods/perovskite solar cells

Energy Technology Data Exchange (ETDEWEB)

Shirahata, Yasuhiro; Tanaike, Kohei; Akiyama, Tsuyoshi; Fujimoto, Kazuya; Suzuki, Atsushi; Balachandran, Jeyadevan; Oku, Takeo, E-mail: oku@mat.usp.ac.jp [Department of Materials Science, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

2016-02-01

ZnO nanorods/perovskite solar cells with different lengths of ZnO nanorods were fabricated. The ZnO nanorods were prepared by chemical bath deposition and directly confirmed to be hexagon-shaped nanorods. The lengths of the ZnO nanorads were controlled by deposition condition of ZnO seed layer. Photovoltaic properties of the ZnO nanorods/CH{sub 3}NH{sub 3}PbI{sub 3} solar cells were investigated by measuring current density-voltage characteristics and incident photon to current conversion efficiency. The highest conversion efficiency was obtained in ZnO nanorods/CH{sub 3}NH{sub 3}PbI{sub 3} with the longest ZnO nanorods.

Preliminary viability studies of fibroblastic cells cultured on microcrystalline and nanocrystalline diamonds produced by chemical vapour deposition method

Directory of Open Access Journals (Sweden)

Ana Amélia Rodrigues

2013-02-01

Full Text Available Implant materials used in orthopedics surgery have demonstrated some disadvantages, such as metallic corrosion processes, generation of wear particles, inflammation reactions and bone reabsorption in the implant region. The diamond produced through hot-filament chemical vapour deposition method is a new potential biomedical material due to its chemical inertness, extreme hardness and low coefficient of friction. In the present study we analysis two samples: the microcrystalline diamond and the nanocrystalline diamond. The aim of this study was to evaluate the surface properties of the diamond samples by scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Cell viability and morphology were assessed using thiazolyl blue tetrazolium bromide, cytochemical assay and scanning electron microscopy, respectively. The results revealed that the two samples did not interfere in the cell viability, however the proliferation of fibroblasts cells observed was comparatively higher with the nanocrystalline diamond.

Evaluation of Alternative Atomistic Models for the Incipient Growth of ZnO by Atomic Layer Deposition

Energy Technology Data Exchange (ETDEWEB)

Chu, Manh-Hung; Tian, Liang; Chaker, Ahmad; Skopin, Evgenii; Cantelli, Valentina; Ouled, Toufik; Boichot, Raphaël; Crisci, Alexandre; Lay, Sabine; Richard, Marie-Ingrid; Thomas, Olivier; Deschanvres, Jean-Luc; Renevier, Hubert; Fong, Dillon; Ciatto, Gianluca

2017-03-20

ZnO thin films are interesting for applications in several technological fields, including optoelectronics and renewable energies. Nanodevice applications require controlled synthesis of ZnO structures at nanometer scale, which can be achieved via atomic layer deposition (ALD). However, the mechanisms governing the initial stages of ALD had not been addressed until very recently. Investigations into the initial nucleation and growth as well as the atomic structure of the heterointerface are crucial to optimize the ALD process and understand the structure-property relationships for ZnO. We have used a complementary suite of in situ synchrotron x-ray techniques to investigate both the structural and chemical evolution during ZnO growth by ALD on two different substrates, i.e., SiO2 and Al2O3, which led us to formulate an atomistic model of the incipient growth of ZnO. The model relies on the formation of nanoscale islands of different size and aspect ratio and consequent disorder induced in the Zn neighbors' distribution. However, endorsement of our model requires testing and discussion of possible alternative models which could account for the experimental results. In this work, we review, test, and rule out several alternative models; the results confirm our view of the atomistic mechanisms at play, which influence the overall microstructure and resulting properties of the final thin film.

Infrared absorption study of hydrogen incorporation in thick nanocrystalline diamond films

International Nuclear Information System (INIS)

Tang, C.J.; Neves, A.J.; Carmo, M.C.

2005-01-01

We present an infrared (IR) optical absorbance study of hydrogen incorporation in nanocrystalline diamond films. The thick nanocrystalline diamond films were synthesized by microwave plasma-assisted chemical vapor deposition and a high growth rate about 3.0 μm/h was achieved. The morphology, phase quality, and hydrogen incorporation were assessed by means of scanning electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). Large amount of hydrogen bonded to nanocrystalline diamond is clearly evidenced by the huge CH stretching band in the FTIR spectrum. The mechanism of hydrogen incorporation is discussed in light of the growth mechanism of nanocrystalline diamond. This suggests the potential of nanocrystalline diamond for IR electro-optical device applications

Effects of Annealing Temperature on Properties of Ti-Ga-Doped ZnO Films Deposited on Flexible Substrates.

Science.gov (United States)

Chen, Tao-Hsing; Chen, Ting-You

2015-11-03

An investigation is performed into the optical, electrical, and microstructural properties of Ti-Ga-doped ZnO films deposited on polyimide (PI) flexible substrates and then annealed at temperatures of 300 °C, 400 °C, and 450 °C, respectively. The X-ray diffraction (XRD) analysis results show that all of the films have a strong (002) Ga doped ZnO (GZO) preferential orientation. As the annealing temperature is increased to 400 °C, the optical transmittance increases and the electrical resistivity decreases. However, as the temperature is further increased to 450 °C, the transmittance reduces and the resistivity increases due to a carbonization of the PI substrate. Finally, the crystallinity of the ZnO film improves with an increasing annealing temperature only up to 400 °C and is accompanied by a smaller crystallite size and a lower surface roughness.

High rate (∼7 nm/s), atmospheric pressure deposition of ZnO front electrode for Cu(In,Ga)Se2 thin-film solar cells with efficiency beyond 15%

NARCIS (Netherlands)

Illiberi, A.; Grob, F.; Frijters, C.; Poodt, P.; Ramachandra, R.; Winands, H.; Simor, M.; Bolt, P.J.

2013-01-01

Undoped zinc oxide (ZnO) films have been grown on a moving glass substrate by plasma-enhanced chemical vapor deposition at atmospheric pressure. High deposition rates of ∼7 nm/s are achieved at low temperature (200°C) for a substrate speed from 20 to 60 mm/min. ZnO films are highly transparent in

Nanocystalline ZnO films prepared via polymeric precursor method (Pechini)

Energy Technology Data Exchange (ETDEWEB)

Sanchez, C.; Doria, J.; Paucar, C.; Hernandez, M. [Laboratorio de Materiales Ceramicos y Vitreos, Universidad Nacional de Colombia, Sede Medellin, A.A. 568, Medellin (Colombia); Mosquera, A.; Rodriguez, J.E. [Grupo CYTEMAC, Universidad del Cauca, Calle 5 No 4-70, Popayan (Colombia); Gomez, A. [Departamento de Ingenieria de Materiales, Universidad Nacional de Colombia, sede Medellin, A.A. 568, Medellin (Colombia); Baca, E. [Grupo de Ingenieria de Nuevos Materiales, Universidad del Valle, A.A. 25360 Cali (Colombia); Moran, O., E-mail: omoranc@unal.edu.c [Laboratorio de Materiales Ceramicos y Vitreos, Universidad Nacional de Colombia, Sede Medellin, A.A. 568, Medellin (Colombia)

2010-09-01

The polymeric precursor method (Pechini) was employed to prepare high-quality nanocrystalline zinc oxide (ZnO) films. Briefly, the process started off with the preparation of a coating solution by the Pechini process followed by a coating of the glass substrates by a dip-coating technique and subsequent heat-treatment of the as-deposited films up to 550 {sup o}C for 30 min. The Rietveld profile analysis of the X-ray diffraction (XRD) spectra revealed the wuerzite structure as expected for ZnO with a P6{sub 3}mc symmetry. No additional peaks were observed that would correspond to any secondary crystalline phase. The average crystallites size was 20 nm as calculated by Sherrer's equation. UV-vis spectroscopy showed sharp ultraviolet absorption edges at {approx}380 nm. The absorption edge analysis yielded optical band gap energy of 3.24 eV with electronic transition of the direct transition type. The Fourier transform infrared (FTIR) analysis showed asymmetric and symmetric stretching modes of the carboxyl group (C=O). Scanning electron microscope (SEM) analysis revealed a crack-free surface morphology indicating that coating of the amorphous glass substrates was homogeneous on large surface areas. The temperature dependent conductivity featured a typical semiconducting-like behavior with resistivity approaching 3x10{sup -1} {Omega} cm at 220 K.

Morphology dependent dye-sensitized solar cell properties of nanocrystalline zinc oxide thin films

Energy Technology Data Exchange (ETDEWEB)

Sharma, S.K., E-mail: sanjeevlrs732000@yahoo.co.in [Department of Information and Communication, Cheju Halla College, Jeju City 690 708 (Korea, Republic of); Inamdar, A.I.; Im, Hyunsik [Department of Semiconductor Science, Dongguk University, Seoul 100 715 (Korea, Republic of); Kim, B.G. [Department of Information and Communication, Cheju Halla College, Jeju City 690 708 (Korea, Republic of); Patil, P.S. [Thin Film Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)

2011-02-03

Research highlights: > Nano-crystalline zinc oxide thin films were electrosynthesized from an aqueous zinc acetate [Zn(CH{sub 3}COO){sub 2}.2H{sub 2}O] solution onto FTO coated conducting glass substrates using two different electrochemical routes, namely (i) without an organic surfactant and (ii) with an organic surfactant, viz. PVA (poly-vinyl alcohol) or SDS (sodium dodecyl sulfate). > The reproducibility of the catalytic activity of the SDS and PVA surfactants in the modification of the morphologies was observed. > Vertically aligned nest-like and compact structures were observed from the SDS and PVA mediated films, respectively, while the grain size in the ZnO thin films without an organic surfactant was observed to be {approx}150 nm. > The dye sensitized ZnO electrodes displayed excellent properties in the conversion process from light to electricity. The efficiencies of the surfactant mediated nanocrystalline ZnO thin films, viz. ZnO:SDS and ZnO:PVA, sensitized with ruthenium-II (N3) dye were observed to be 0.49% and 0.27%, respectively. - Abstract: Nano-crystalline zinc oxide thin films were electrosynthesized with an aqueous zinc acetate [Zn(CH{sub 3}COO){sub 2}.2H{sub 2}O] solution on to FTO coated glass substrates. Two different electrochemical baths were used, namely (i) without an organic surfactant and (ii) with an organic surfactant, viz. PVA (poly-vinyl alcohol) and SDS (sodium dodecyl sulfate). The organic surfactants played an important role in modifying the surface morphology, which influenced the size of the crystallites and dye-sensitized solar cell (DSSC) properties. The vertically aligned thin and compact hexagonal crystallites were observed with SDS mediated films, while the grain size in the films without an organic surfactant was observed to be {approx}150 nm. The conversion efficiencies of the ZnO:SDS:Dye and ZnO:PVA:Dye thin films were observed to be 0.49% and 0.27%, respectively.

Characterization of nanostructured ZnO thin films deposited through vacuum evaporation

Directory of Open Access Journals (Sweden)

Jose Alberto Alvarado

2015-04-01

Full Text Available This work presents a novel technique to deposit ZnO thin films through a metal vacuum evaporation technique using colloidal nanoparticles (average size of 30 nm, which were synthesized by our research group, as source. These thin films had a thickness between 45 and 123 nm as measured by profilometry. XRD patterns of the deposited thin films were obtained. According to the HRSEM micrographs worm-shaped nanostructures are observed in samples annealed at 600 °C and this characteristic disappears as the annealing temperature increases. The films obtained were annealed from 25 to 1000 °C, showing a gradual increase in transmittance spectra up to 85%. The optical band gaps obtained for these films are about 3.22 eV. The PL measurement shows an emission in the red and in the violet region and there is a correlation with the annealing process.

Self-limiting growth of ZnO films on (0 0 0 1) sapphire substrates by atomic layer deposition at low temperatures using diethyl-zinc and nitrous oxide

International Nuclear Information System (INIS)

Lin, Yen-Ting; Chung, Ping-Han; Lai, Hung-Wei; Su, Hsin-Lun; Lyu, Dong-Yuan; Yen, Kuo-Yi; Lin, Tai-Yuan; Kung, Chung-Yuan; Gong, Jyh-Rong

2009-01-01

Atomic layer deposition (ALD) of zinc oxide (ZnO) films on (0 0 0 1) sapphire substrates was conducted at low temperatures by using diethyl-zinc (DEZn) and nitrous oxide (N 2 O) as precursors. It was found that a monolayer-by-monolayer growth regime occurred at 300 deg. C in a range of DEZn flow rates from 5.7 to 8.7 μmol/min. Furthermore, the temperature self-limiting process window for the ALD-grown ZnO films was also observed ranging from 290 to 310 deg. C. A deposition mechanism is proposed to explain how saturated growth of ZnO is achieved by using DEZn and N 2 O. Transmission spectroscopic studies of the ZnO films prepared in the self-limiting regime show that the transmittances of ZnO films are as high as 80% in visible and near infrared spectra. Experimental results indicate that ZnO films with high optical quality can be achieved by ALD at low temperatures using DEZn and N 2 O precursors.

Effects of intermittent atomization on the properties of Al-doped ZnO thin films deposited by aerosol-assisted chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Liu, Linjie; Wang, Lixin [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); Qin, Xiujuan, E-mail: qinxj@ysu.edu.cn [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); Cui, Li [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); Shao, Guangjie [Hebei Key Laboratory of Applied Chemistry, Yanshan University, Qinhuangdao 066004 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)

2016-04-30

Al-doped ZnO (AZO) thin films were prepared on glass substrates with different atomization interval times by aerosol-assisted chemical vapor deposition method. The structure, morphology, and optical and electrical properties were investigated by X-ray diffractometer, atomic force microscope, UV-vis double beam spectrophotometer and 4 point probe method. ZnO thin films exhibited strong growth orientation along the (002) plane and the crystalline was affected by the atomization interval time. All the films had high transmittance and the films with interval times of 2 min and 4 min had good haze values for the transparent conducting oxide silicon solar cell applications. The AZO thin film had the best optical and electrical properties when the atomization interval time was 4 min. This is very important for the optoelectronic device applications. The surface morphology of AZO films depended on the atomization interval time. - Highlights: • Intermittent atomization is proved to be an effective measure. • Atomization interval time has an important influence on the crystallinity of films. • The surface morphology of ZnO films depends on atomization interval time. • Different hazes can be obtained by changing the atomization interval time.

Effects of intermittent atomization on the properties of Al-doped ZnO thin films deposited by aerosol-assisted chemical vapor deposition

International Nuclear Information System (INIS)

Liu, Linjie; Wang, Lixin; Qin, Xiujuan; Cui, Li; Shao, Guangjie

2016-01-01

Al-doped ZnO (AZO) thin films were prepared on glass substrates with different atomization interval times by aerosol-assisted chemical vapor deposition method. The structure, morphology, and optical and electrical properties were investigated by X-ray diffractometer, atomic force microscope, UV-vis double beam spectrophotometer and 4 point probe method. ZnO thin films exhibited strong growth orientation along the (002) plane and the crystalline was affected by the atomization interval time. All the films had high transmittance and the films with interval times of 2 min and 4 min had good haze values for the transparent conducting oxide silicon solar cell applications. The AZO thin film had the best optical and electrical properties when the atomization interval time was 4 min. This is very important for the optoelectronic device applications. The surface morphology of AZO films depended on the atomization interval time. - Highlights: • Intermittent atomization is proved to be an effective measure. • Atomization interval time has an important influence on the crystallinity of films. • The surface morphology of ZnO films depends on atomization interval time. • Different hazes can be obtained by changing the atomization interval time.

Atomic layer deposition grown composite dielectric oxides and ZnO for transparent electronic applications

International Nuclear Information System (INIS)

Gieraltowska, S.; Wachnicki, L.; Witkowski, B.S.; Godlewski, M.; Guziewicz, E.

2012-01-01

In this paper, we report on transparent transistor obtained using laminar structure of two high-k dielectric oxides (hafnium dioxide, HfO 2 and aluminum oxide, Al 2 O 3 ) and zinc oxide (ZnO) layer grown at low temperature (60 °C–100 °C) using Atomic Layer Deposition (ALD) technology. Our research was focused on the optimization of technological parameters for composite layers Al 2 O 3 /HfO 2 /Al 2 O 3 for thin film transistor structures with ZnO as a channel and a gate layer. We elaborate on the ALD growth of these oxides, finding that the 100 nm thick layers of HfO 2 and Al 2 O 3 exhibit fine surface flatness and required amorphous microstructure. Growth parameters are optimized for the monolayer growth mode and maximum smoothness required for gating.

Relative Humidity Sensing Properties Of Cu2O Doped ZnO Nanocomposite

International Nuclear Information System (INIS)

Pandey, N. K.; Tiwari, K.; Tripathi, A.; Roy, A.; Rai, A.; Awasthi, P.

2009-01-01

In this paper we report application of Cu 2 O doped ZnO composite prepared by solid state reaction route as humidity sensor. Pellet samples of ZnO-Cu 2 O nanocrystalline powders with 2, 5 and 10 weight% of Cu 2 O in ZnO have been prepared. Pellets have been annealed at temperatures of 200-500 deg. C and exposed to humidity. It is observed that as relative humidity increases, resistance of the pellet decreases for the humidity from 10% to 90%. Sample with 5% of Cu 2 O doped in ZnO and annealed at 500 deg. C shows best results with sensitivity of 1.50 MΩ/%RH. In this case the hysteresis is low and the reproducibility high, making it the suitable candidate for humidity sensing.

ZnO nanorod arrays prepared by chemical bath deposition combined with rapid thermal annealing: structural, photoluminescence and field emission characteristics

International Nuclear Information System (INIS)

Chen, Hung-Wei; He, Hsin-Min; Lee, Yi-Mu; Yang, Hsi-Wen

2016-01-01

ZnO nanorod arrays were prepared by low temperature chemical bath deposition (CBD) combined with rapid thermal annealing (RTA) under different ambient conditions. The structure and morphology of the synthesized ZnO have been characterized by field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). The obtained ZnO samples are highly crystalline with a hexagonal wurtzite phase and also display well-aligned array structure. A pronounced effect on increased nanorod length was found for the RTA-treated ZnO as compared to the as-grown ZnO. Analysis of XRD indicates that the (0 0 2) feature peak of the as-grown ZnO was shifted towards a lower angle as compared to the peaks of RTA-treated ZnO samples due to the reduction of tensile strain along the c-axis by RTA. Photoluminescence (PL) studies reveal that the ZnO nanorod arrays receiving RTA in an O 2 environment have the sharpest UV emission band and greatest intensity ratio of near band-edge emission (NBE) to deep level emission (DLE). Additionally, the effects of RTA on the field emission properties were evaluated. The results demonstrate that RTA an O 2 environment can lower the turn-on field and improve the field enhancement factor. The stability of the field emission current was also tested for 4 h. (paper)

Catalyst growth of single crystal aligned ZnO nanorods on ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Zhao, Dongxu; Andreazza, Caroline; Andreazza, Pascal [Centre de Recherche sur la Matiere Divisee, CNRS-Universite d' Orleans, 1b rue de la Ferollerie, 45071 Orleans cedex 2 (France)

2005-02-01

One dimensional ZnO nanorods were successfully fabricated on Si substrates via a simple physical vapor-phase transport method at 950 C. A ZnO shell covered Au/Zn alloy is assumed as the nucleation site, then ZnO nanorods grow following a vapor-solid (VS) process. In order to guide the nanorod growth a c-axis oriented ZnO thin film and Au catalyst were first deposited on Si (100) surface. SEM images show nanorods grown on this substrate are vertical to the substrate surface. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effects of oxide distributed in grain boundaries on microstructure stability of nanocrystalline metals

Science.gov (United States)

Zhou, Kai; Li, Hui; Biao Pang, Jin; Wang, Zhu

2013-06-01

Nanocrystalline copper and zinc prepared by high-pressure compaction method have been studied by positron lifetime spectroscopy associated with X-ray diffraction. For nanocrystalline Cu, mean grain sizes of the samples decrease after being annealed at 900 °C and increase during aging at 180 °C, revealing that the atoms exchange between the two regions. The positron lifetime results indicate that the vacancy clusters formed in the annealing process are unstable and decomposed at the aging time below 6 hours. In addition, the partially oxidized surfaces of the nanoparticles hinder the grain growth during the ageing at 180 °C, and the vacancy clusters inside the disorder regions which are related to Cu2O need longer aging time to decompose. In the case of nanocrystalline Zn, the open volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ1). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τav) during the annealing, which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. For both nanocrystalline copper and zinc, the oxides in grain boundaries enhance the thermal stability of the microstucture, in spite of their different crystal structures. This effect is very important for the nanocrystalline materials using as radiation resistant materials.

Effects of oxide distributed in grain boundaries on microstructure stability of nanocrystalline metals

International Nuclear Information System (INIS)

Zhou Kai; Li Hui; Pang Jinbiao; Wang Zhu

2013-01-01

Nanocrystalline copper and zinc prepared by high-pressure compaction method have been studied by positron lifetime spectroscopy associated with X-ray diffraction. For nanocrystalline Cu, mean grain sizes of the samples decrease after being annealed at 900 °C and increase during aging at 180 °C, revealing that the atoms exchange between the two regions. The positron lifetime results indicate that the vacancy clusters formed in the annealing process are unstable and decomposed at the aging time below 6 hours. In addition, the partially oxidized surfaces of the nanoparticles hinder the grain growth during the ageing at 180 °C, and the vacancy clusters inside the disorder regions which are related to Cu 2 O need longer aging time to decompose. In the case of nanocrystalline Zn, the open volume defect (not larger than divacancy) is dominant according to the high relative intensity for the short positron lifetime (τ 1 ). The oxide (ZnO) inside the grain boundaries has been found having an effect to hinder the decrease of average positron lifetime (τ av ) during the annealing, which probably indicates that the oxide stabilizes the microstructure of the grain boundaries. For both nanocrystalline copper and zinc, the oxides in grain boundaries enhance the thermal stability of the microstucture, in spite of their different crystal structures. This effect is very important for the nanocrystalline materials using as radiation resistant materials.

Optical band gap of ZnO thin films deposited by electron beam evaporation

International Nuclear Information System (INIS)

Nadeem, M. Y.; Ali, S. L.; Wasiq, M. F.; Rana, A. M.

2006-01-01

Optical band gap of ZnO thin films deposited by electron beam evaporation at evaporation rates ranging 5 As/sup -1/ to 15 As /sup -1/ and thickness ranging 1000A to 3000A is presented. Deposited films were annealed at 573K for one and half hour. The variations in the optical band gap were observed and showed decreasing behavior from 3.15 eV, 3.05 eV, from 3.18 eV to 3.10 eV and from 3.19 eV to 3.18 eV for films with respective thickness 1000A, 2000 A, 3000 A on increasing the evaporation rate from 5 As/sup-1/ to As/sup -1/ by keeping thickness constant. (author)

Characterization of nanostructures of ZnO and ZnMnO films deposited by successive ionic layer adsorption and reaction method

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Garcia, F.N. [Departamento de Fisica y Matematicas, Universidad Autonoma de Manizales, Antigua Estacion del Ferrocarril, Manizales, Caldas (Colombia); Departamento de Fisica y Quimica, Universidad Nacional de Colombia, Sede Manizales, Campus la Nubia, Manizales, Caldas (Colombia); Espinosa-Arbelaez, D.G. [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Blv. Juriquilla 3001, Juriquilla, Queretaro, C.P. 76230 (Mexico); Posgrado en Ciencia e Ingenieria Materiales, Instituto de Investigacion en Materiales, Universidad Nacional Autonoma de Mexico, Mexico DF (Mexico); Vargas-Hernandez, C. [Departamento de Fisica y Quimica, Universidad Nacional de Colombia, Sede Manizales, Campus la Nubia, Manizales, Caldas (Colombia); Real, A. del [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Blv. Juriquilla 3001, Juriquilla, Queretaro, C.P. 76230 (Mexico); Rodriguez-Garcia, M.E., E-mail: marioga@fata.unam.mx [Departamento de Nanotecnologia, Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Blv. Juriquilla 3001, Juriquilla, Queretaro, C.P. 76230 (Mexico)

2011-09-01

ZnO and ZnMnO thin films were obtained by the successive ionic layer adsorption and reaction (SILAR) method. All thin films were deposited on glass microscope slide. A precursor solution of 0.1 M of ZnCl{sub 2} complexed with ammonium hydroxide and water close to boiling point (92 deg. C) as a second solution was used for the ZnO films. An uncomplexed bath comprised of 0.1 M ZnCl{sub 2}, 0.1 M MnCl{sub 2,} and a second solution of 0.1 ml of NH{sub 4}OH with water close to boiling point was used for the ZnMnO films. The film samples were deposited by the SILAR method and annealed at 200 deg. C for 15 min. These samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (EDS), and Atomic Force Microscope. Atomic absorption was used to determine quantitatively the amount of Mn incorporated into the films. According to the XRD patterns these films were polycrystalline with wurtzite hexagonal structure. The morphology of the ZnO films constituted by rice-like and flower-like structures changed significantly to nanosheet structures with the Mn incorporation. The Mn inclusion in a ZnO structure was less than 4% according to the results from EDS, XRD, and atomic absorption.

Characterization of nanostructures of ZnO and ZnMnO films deposited by successive ionic layer adsorption and reaction method

International Nuclear Information System (INIS)

Jimenez-Garcia, F.N.; Espinosa-Arbelaez, D.G.; Vargas-Hernandez, C.; Real, A. del; Rodriguez-Garcia, M.E.

2011-01-01

ZnO and ZnMnO thin films were obtained by the successive ionic layer adsorption and reaction (SILAR) method. All thin films were deposited on glass microscope slide. A precursor solution of 0.1 M of ZnCl 2 complexed with ammonium hydroxide and water close to boiling point (92 deg. C) as a second solution was used for the ZnO films. An uncomplexed bath comprised of 0.1 M ZnCl 2 , 0.1 M MnCl 2, and a second solution of 0.1 ml of NH 4 OH with water close to boiling point was used for the ZnMnO films. The film samples were deposited by the SILAR method and annealed at 200 deg. C for 15 min. These samples were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (EDS), and Atomic Force Microscope. Atomic absorption was used to determine quantitatively the amount of Mn incorporated into the films. According to the XRD patterns these films were polycrystalline with wurtzite hexagonal structure. The morphology of the ZnO films constituted by rice-like and flower-like structures changed significantly to nanosheet structures with the Mn incorporation. The Mn inclusion in a ZnO structure was less than 4% according to the results from EDS, XRD, and atomic absorption.

Crystallinity improvement of ZnO nanorods by optimization of low-cost electrodeposition technique

Energy Technology Data Exchange (ETDEWEB)

Özdal, Teoman, E-mail: teomanozdal@hotmail.com; Taktakoğlu, Renna; Özdamar, Havva; Esen, Mehmet; Takçı, Deniz Kadir; Kavak, Hamide

2015-10-01

Extremely low-cost electrodeposition technique was developed to deposit ZnO nanorods. The growth process was performed using standard DC power supply, milliammeter and two-electrode electrochemical cell. The deposition was carried out on indium tin oxide (ITO) coated glass substrates by changing deposition parameters such as cathodic deposition current and time, solution molarity and temperature. The parameters varied to obtain optimum transparent semiconductor material for optoelectronic applications. Structural characterizations by X-ray diffraction (XRD) indicate the formation of polycrystalline phase ZnO with strong c-axis orientation and were sensitive to deposition temperatures and molarity as well. Average optical transmittance for the best two ZnO nanorod series was around 60% and 42%, respectively. The optical energy band gap of the ZnO nanorods decreased from 3.24 eV to 3.21 eV as the deposition time increased. All the nanorods were n-type with a high carrier concentration of 1 × 10{sup 20} cm{sup −3} and low 1–2 × 10{sup −3} Ωcm resistivity. - Highlights: • n-Type ZnO nanorods were electrochemically deposited employing standard DC power supply and milliammeter. • ZnO nanorods show very good polycrystalline and electrical properties consistent with the literature. • ZnO nanorod structures are hexagonal wurtzite and highly oriented along the c-axis perpendicular to the substrates. • Produced ZnO nanorod structures show good transparent conductive oxide properties.

Nanocrystalline Ni-Co Alloy Synthesis by High Speed Electrodeposition

OpenAIRE

Idris, Jamaliah; Christian, Chukwuekezie; Gaius, Eyu

2013-01-01

Electrodeposition of nanocrystals is economically and technologically viable production path for the synthesis of pure metals and alloys both in coatings and bulk form. The study presents nanocrystalline Ni-Co alloy synthesis by high speed electrodeposition. Nanocrystalline Ni-Co alloys coatings were prepared by direct current (DC) and deposited directly on steel and aluminum substrates without any pretreatment, using high speed electrodeposition method. The influence of the electrolysis par...

Enhanced Performance of Nanowire-Based All-TiO2 Solar Cells using Subnanometer-Thick Atomic Layer Deposited ZnO Embedded Layer

International Nuclear Information System (INIS)

Ghobadi, Amir; Yavuz, Halil I.; Ulusoy, T. Gamze; Icli, K. Cagatay; Ozenbas, Macit; Okyay, Ali K.

2015-01-01

In this paper, the effect of angstrom-thick atomic layer deposited (ALD) ZnO embedded layer on photovoltaic (PV) performance of Nanowire-Based All-TiO 2 solar cells has been systematically investigated. Our results indicate that by varying the thickness of ZnO layer the efficiency of the solar cell can be significantly changed. It is shown that the efficiency has its maximum for optimal thickness of 1 ALD cycle in which this ultrathin ZnO layer improves device performance through passivation of surface traps without hampering injection efficiency of photogenerated electrons. The mechanisms contributing to this unprecedented change in PV performance of the cell have been scrutinized and discussed

Effect of ion beam irradiation on the structure of ZnO films deposited by a dc arc plasmatron.

Science.gov (United States)

Penkov, Oleksiy V; Lee, Heon-Ju; Plaksin, Vadim Yu; Ko, Min Gook; Joa, Sang Beom; Yim, Chan Joo

2008-02-01

The deposition of polycrystalline ZnO film on a cold substrate was performed by using a plasmatron in rough vacuum condition. Low energy oxygen ion beam generated by a cold cathode ion source was introduced during the deposition process. The change of film property on the ion beam energy was checked. It is shown that irradiation by 200 eV ions improves crystalline structure of the film. Increasing of ion beam energy up to 400 eV leads to the degradation of a crystalline structure and decreases the deposition rate.

Structure and Properties of Al and Ga- Doped ZnO

Science.gov (United States)

Temizer, Namik Kemal

Recently there is tremendous interest in Transparent conducting oxide (TCO) research due to the unlimited and exciting application areas. Current research is mostly focused on finding alternative low cost and sustainable materials in order to replace indium tin oxide (ITO), which caused serious concern due to the increasing cost of indium and chemical stability issues of ITO. The primary aim of this research is to develop alternative TCO materials with superior properties in order to increase the efficiency in optoelectronic applications, as well as to study the properties of these materials to fully characterize them. We have grown Al and Ga-doped ZnO films with an optimized composition under different deposition conditions in order to understand the effect of processing parameters on the film properties. We report a detailed investigation on the structure-property correlations in Ga and Al codoped ZnO films on c-sapphire substrates where the thin film microstructure varies from nanocrystalline to single crystal. We have achieved highly epitaxial films with very high optical transmittance (close to 90%) and low resistivity (˜110muO-cm) values. The films grown in an ambient oxygen partial pressure (PO2 ) of 50 mTorr and at growth temperatures from room temperature to 600°C showed semiconducting behavior, whereas samples grown at a Po2 of 1 mTorr showed metallic nature. The most striking feature is the occurrence of resistivity minima at relatively high temperatures around 110 K in films deposited at high temperatures. The structure-property correlations reveal that point defects play an important role in modifying the structural, optical, electrical and magnetic properties and such changes in physical properties are controlled predominantly by the defect content. To gain a better understanding of the conduction processes in doped ZnO thin films, we have studied the temperature variation of resistivity of some selected samples that showed some interesting behavior

Photoluminescence study of novel phosphorus-doped ZnO nanotetrapods synthesized by chemical vapour deposition

International Nuclear Information System (INIS)

Yu Dongqi; Hu Lizhong; Qiao Shuangshuang; Zhang Heqiu; Fu Qiang; Chen Xi; Sun Kaitong; Len, Song-En Andy; Len, L K

2009-01-01

Novel phosphorus-doped and undoped single crystal ZnO nanotetrapods were fabricated on sapphire by a simple chemical vapour deposition method, using phosphorus pentoxide (P 2 O 5 ) as the dopant source. The optical properties of the samples were investigated by photoluminescence (PL) spectroscopy. Low-temperature PL measurements of phosphorus-doped and undoped samples were compared, and the results indicated a decrease in deep level defects due to the incorporation of a phosphorus acceptor dopant. The PL spectrum of the phosphorus-doped sample at 10 K exhibited several acceptor-bound exciton related emission peaks. The effect of phosphorus doping on the optical characteristics of the samples was investigated by excitation intensity and temperature dependent PL spectra. The acceptor-binding energies of the phosphorus dopant were estimated to be about 120 meV, in good agreement with the corresponding theoretical and experimental values in phosphorus-doped ZnO films and nanowires.

Tuning of Ag doped core−shell ZnO NWs/Cu2O grown by electrochemical deposition

International Nuclear Information System (INIS)

Makhlouf, Houssin; Messaoudi, Olfa; Souissi, Ahmed; Ben Assaker, Ibtissem; Oueslati, Mihrez; Bechelany, Mikhael; Chtourou, Radhouane

2015-01-01

ZnO nanowires (NWs)/Cu 2 O–Ag core–shell nanostructures (NSs) have been synthesized by electrochemical deposition method on ITO-coated glass substrates in order to improve the efficiency of the type-II transition of core–shell ZnO NWs/Cu 2 O–Ag NSs. The morphologies of the obtained NSs were studied by scanning electron microscopy confirming the presence of core–shell NSs. The crystalline proprieties were analyzed by x-ray diffraction and micro-Raman measurement: wurtzite ZnO and cuprit Cu 2 O phase were founded. The presence of Ag content in core–shell NS was detected by EDX. Optical measurement reveals an additional contribution δE at about 1.72 eV attributed to the type-II interfacial transition between the valance band of cuprit−Cu 2 O and the conduction band of W−ZnO. The effect of the Ag doping into the type-II transition was investigated. A red shift of the type-II transition was detected according to the Ag concentration. These materials could have potential applications in photocatalytic and photovoltaic fields. (paper)

Effect of plating time on growth of nanocrystalline Ni–P from ...

Indian Academy of Sciences (India)

Nanocrystalline nickel phosphorus (NC-Ni–P) deposits from sulphate/glycine bath using a simple electroless deposition process is demonstrated. In the present investigation, nanoporous alumina films are formed on the aluminium surface by anodization process followed by deposition of nickel onto the pores by electroless ...

ZnO films grown by pulsed-laser deposition on soda lime glass substrates for the ultraviolet inactivation of Staphylococcus epidermidis biofilms

Directory of Open Access Journals (Sweden)

Jean-Paul Mosnier, Richard J O'Haire, Enda McGlynn, Martin O Henry, Stephen J McDonnell, Maria A Boyle and Kevin G McGuigan

2009-01-01

Full Text Available We found that a ZnO film of 2 μm thickness which was laser-deposited at room temperature onto a plain soda lime glass substrate, exhibits notable antibacterial activity against a biofilm of Staphylococcus epidermidis when back-illuminated by a UVA light source with a peak emission wavelength of about 365 nm. X-ray diffraction (XRD, scanning electron microscopy (SEM, atomic force microscopy (AFM, UV-visible absorption spectroscopy, Raman spectroscopy and x-ray photoemission spectroscopy (XPS were used to characterize the ZnO films before and after the interactions with the biofilm and the ultraviolet light, respectively. The as-deposited film was highly textured with the wurtzite (0002 in-plane orientation (c-axis perpendicular to ZnO surface and had a surface rms roughness of 49.7 nm. In the as-deposited film, the Zn to O ratio was 1 to 0.95. After the UV and biofilm treatments, the ZnO film surface had become rougher (rms roughness 68.1 nm and presented uniform micron-sized pitting randomly distributed, while the zinc to oxygen ratio had become 1 to 2.2. In this case, both the UV-visible and Raman spectra pointed to degradation of the structural quality of the material. On the strength of these data, we propose a model for the mediation of the bactericidal activity in which the photogeneration of highly oxidizing species and the presence of active surface defect sites both play an important role. This study is of particular interest for the acute problem of disinfection of pathogenic biofilms which form on medical device/implant surfaces.

Effect of reaction time on structural, morphology and optical properties of ZnO nanoflakes prepared by chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Molefe, F.V.; Koao, L.F., E-mail: koaolf@qwa.ufs.ac.za; Dolo, J.J.; Dejene, B.F.

2014-04-15

ZnO nanoflakes have been successfully synthesized by the chemical bath deposition (CBD) method for different reaction times. X-ray diffraction (XRD) results confirm the initial formation of the cubic ZnO structure. However, increasing the reaction time resulted into the emergence of the well-known hexagonal wurtzite structure of ZnO. Scanning electron microscopy images showed the presence of agglomerated nanoflakes. The morphology was found not to depend on synthesis time. UV–vis spectra showed a partially increase in the percentage reflectance and the absorption edges red shifted to the higher wavelength with an increase in synthesis time. The highest band gap energy was obtained for ZnO synthesized for 1 min, with its estimated band gap energy of 3.91±0.08 eV. The estimated band gap decreased with an increase in the reaction time. The photoluminescent intensity of the emission peak at 473 nm decreased with an increase in reaction time.

Synthesis and microstructural characterization of growth direction controlled ZnO nanorods using a buffer layer

International Nuclear Information System (INIS)

Park, Dong Jun; Kim, Dong Chan; Lee, Jeong Yong; Cho, Hyung Koun

2006-01-01

The growth direction and morphology of one-dimensional ZnO nanostructures grown by metal-organic chemical vapour deposition (MOCVD) were modulated by changing the growth temperature of previously deposited ZnO buffer layers that were used as a template. The ZnO nanorods grown on the low-temperature deposited buffer layer were regularly inclined with respect to the substrate surface and show in-plane alignment with azimuthally six-fold symmetry. In contrast, deposition of the buffer layer at higher growth temperature led to the formation of vertically well-aligned ZnO nanorods. In addition, the ZnO nanorods grown on the buffer layer deposited at low growth temperature show a growth direction of [1 0 1-bar 0], unlike the conventional ZnO nanorods showing a growth direction of [0001]. The microstructural analysis and atomic modelling of the formation of regularly inclined nanorods using transmission electron microscopy are presented

Mg-doped ZnO thin films deposited by the atomic layer chemical vapor deposition for the buffer layer of CIGS solar cell

Energy Technology Data Exchange (ETDEWEB)

Li, Zhao-Hui [Department of Electronics Engineering, Gachon University, Soojung-gu, Seongnam city 461-701, Gyunggi-do (Korea, Republic of); Center for Photovoltaic and Solar Energy, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen city 518055 (China); Cho, Eou-Sik [Department of Electronics Engineering, Gachon University, Soojung-gu, Seongnam city 461-701, Gyunggi-do (Korea, Republic of); Kwon, Sang Jik, E-mail: sjkwon@gachon.ac.kr [Department of Electronics Engineering, Gachon University, Soojung-gu, Seongnam city 461-701, Gyunggi-do (Korea, Republic of)

2014-09-30

Highlights: • Mg-doped ZnO film as CIGS buffer was prepared by ALD process. • The grain size of ZnO-like hexagonal phase decreased with Mg content. • The transmittance and crystallinity increased but the band gap decreased with temperature. - Abstract: Mg-doped ZnO [(Zn, Mg)O] thin films were prepared by atomic layer chemical vapor deposition (ALCVD) process with different Mg content, using diethyl zinc, biscyclopentadienyl magnesium, and water as the metal and oxygen sources, respectively. The ratio of Mg to Zn was varied by changing the pulse ratio of MgCp{sub 2} to DEZn precursor to study its effect on the properties of (Zn, Mg)O thin films. From the experimental results, it was shown that the grain size of the ZnO-like hexagonal phase (Zn, Mg)O decreased as the Mg content increased. But the transmittance and optical band gap of (Zn, Mg)O films increased with the increase of the Mg content. In addition, the effect of the substrate temperature on the properties of (Zn, Mg)O films was also investigated. The deposition rate, transmittance, and crystallinity of (Zn, Mg)O films increased as the substrate temperature increased. But its band gap decreased slightly with the increase of substrate temperature.

Phosphorus acceptor doped ZnO nanowires prepared by pulsed-laser deposition

International Nuclear Information System (INIS)

Cao, B Q; Lorenz, M; Rahm, A; Wenckstern, H von; Czekalla, C; Lenzner, J; Benndorf, G; Grundmann, M

2007-01-01

Phosphorus-doped ZnO (ZnO:P) nanowires were successfully prepared by a novel high-pressure pulsed-laser deposition process using phosphorus pentoxide as the dopant source. Detailed cathodoluminescence studies of single ZnO:P nanowires revealed characteristic phosphorus acceptor-related peaks: neutral acceptor-bound exciton emission (A 0 , X, 3.356 eV), free-to-neutral-acceptor emission (e, A 0 , 3.314 eV), and donor-to-acceptor pair emission (DAP, ∼3.24 and ∼3.04 eV). This means that stable acceptor levels with a binding energy of about 122 meV have been induced in the nanowires by phosphorus doping. Moreover, the induced acceptors are distributed homogeneously along the doped nanowires

ZnO Thin Film Electronics for More than Displays

Science.gov (United States)

Ramirez, Jose Israel

Zinc oxide thin film transistors (TFTs) are investigated in this work for large-area electronic applications outside of display technology. A constant pressure, constant flow, showerhead, plasma-enhanced atomic layer deposition (PEALD) process has been developed to fabricate high mobility TFTs and circuits on rigid and flexible substrates at 200 °C. ZnO films and resulting devices prepared by PEALD and pulsed laser deposition (PLD) have been compared. Both PEALD and PLD ZnO films result in densely packed, polycrystalline ZnO thin films that were used to make high performance devices. PEALD ZnO TFTs deposited at 300 °C have a field-effect mobility of ˜ 40 cm2/V-s (and > 20 cm2/V-S deposited at 200 °C). PLD ZnO TFTs, annealed at 400 °C, have a field-effect mobility of > 60 cm2/V-s (and up to 100 cm2/V-s). Devices, prepared by either technique, show high gamma-ray radiation tolerance of up to 100 Mrad(SiO2) with only a small radiation-induced threshold voltage shift (VT ˜ -1.5 V). Electrical biasing during irradiation showed no enhanced radiation-induced effects. The study of the radiation effects as a function of material stack thicknesses revealed the majority of the radiation-induced charge collection happens at the semiconductor-passivation interface. A simple sheet-charge model at that interface can describe the radiation-induced charge in ZnO TFTs. By taking advantage of the substrate-agnostic process provided by PEALD, due to its low-temperature and excellent conformal coatings, ZnO electronics were monolithically integrated with thin-film complex oxides. Application-based examples where ZnO electronics provide added functionality to complex oxide-based devices are presented. In particular, the integration of arrayed lead zirconate titanate (Pb(Zr, Ti)O3 or PZT) thin films with ZnO electronics for microelectromechanical systems (MEMs) and deformable mirrors is demonstrated. ZnO switches can provide voltage to PZT capacitors with fast charging and slow

ZnO/SnO{sub 2} nanoflower based ZnO template synthesized by thermal chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Sin, N. D. Md., E-mail: diyana0366@johor.uitm.edu.my; Amalina, M. N., E-mail: amalina0942@johor.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Fakulti Kejuruteraan Elektrik, Universiti Teknologi MARA Cawangan Johor, Kampus Pasir Gudang, 81750 Masai, Johor (Malaysia); Ismail, Ahmad Syakirin, E-mail: kyrin-samaxi@yahoo.com; Shafura, A. K., E-mail: shafura@ymail.com; Ahmad, Samsiah, E-mail: samsiah.ahmad@johor.uitm.edu.my; Mamat, M. H., E-mail: mhmamat@salam.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); Rusop, M., E-mail: rusop@salam.uitm.edu.my [NANO-ElecTronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), Institute of Science (IOS), Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia)

2016-07-06

The ZnO/SnO{sub 2} nanoflower like structures was grown on a glass substrate deposited with seed layer using thermal chemical vapor deposition (CVD) with combining two source materials. The ZnO/SnO{sub 2} nanoflower like structures had diameter in the range 70 to 100 nm. The atomic percentage of ZnO nanoparticle , SnO{sub 2} nanorods and ZnO/SnO{sub 2} nanoflower was taken using EDS. Based on the FESEM observations, the growth mechanism is applied to describe the growth for the synthesized nanostructures.

Quantitative and simultaneous analysis of the polarity of polycrystalline ZnO seed layers and related nanowires grown by wet chemical deposition

Science.gov (United States)

Guillemin, Sophie; Parize, Romain; Carabetta, Joseph; Cantelli, Valentina; Albertini, David; Gautier, Brice; Brémond, Georges; Fong, Dillon D.; Renevier, Hubert; Consonni, Vincent

2017-03-01

The polarity in ZnO nanowires is an important issue since it strongly affects surface configuration and reactivity, nucleation and growth, electro-optical properties, and nanoscale-engineering device performances. However, measuring statistically the polarity of ZnO nanowire arrays grown by chemical bath deposition and elucidating its correlation with the polarity of the underneath polycrystalline ZnO seed layer grown by the sol-gel process represents a major difficulty. To address that issue, we combine resonant x-ray diffraction (XRD) at Zn K-edge using synchrotron radiation with piezoelectric force microscopy and polarity-sensitive chemical etching to statistically investigate the polarity of more than 107 nano-objects both on the macroscopic and local microscopic scales, respectively. By using high temperature annealing under an argon atmosphere, it is shown that the compact, highly c-axis oriented ZnO seed layer is more than 92% Zn-polar and that only a few small O-polar ZnO grains with an amount less than 8% are formed. Correlatively, the resulting ZnO nanowires are also found to be Zn-polar, indicating that their polarity is transferred from the c-axis oriented ZnO grains acting as nucleation sites in the seed layer. These findings pave the way for the development of new strategies to form unipolar ZnO nanowire arrays as a requirement for a number of nanoscale-engineering devices like piezoelectric nanogenerators. They also highlight the great advantage of resonant XRD as a macroscopic, non-destructive method to simultaneously and statistically measure the polarity of ZnO nanowire arrays and of the underneath ZnO seed layer.

Effect of power on the growth of nanocrystalline silicon films

International Nuclear Information System (INIS)

Kumar, Sushil; Dixit, P N; Rauthan, C M S; Parashar, A; Gope, Jhuma

2008-01-01

Nanocrystalline silicon thin films were grown using a gaseous mixture of silane, hydrogen and argon in a plasma-enhanced chemical vapor deposition system. These films were deposited away from the conventional low power regime normally used for the deposition of device quality hydrogenated amorphous silicon films. It was observed that, with the increase of applied power, there is a change in nanocrystalline phases which were embedded in the amorphous matrix of silicon. Atomic force microscopy micrographs show that these films contain nanocrystallite of 20-100 nm size. Laser Raman and photoluminescence peaks have been observed at 514 cm -1 and 2.18 eV, respectively, and particle sizes were estimated using the same as 8.24 nm and 3.26 nm, respectively. It has also been observed that nanocrystallites in these films enhanced the optical bandgap and electrical conductivity

Effect of power on the growth of nanocrystalline silicon films

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sushil; Dixit, P N; Rauthan, C M S; Parashar, A; Gope, Jhuma [Plasma Processed Materials Group, National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110 012 (India)], E-mail: skumar@mail.nplindia.ernet.in

2008-08-20

Nanocrystalline silicon thin films were grown using a gaseous mixture of silane, hydrogen and argon in a plasma-enhanced chemical vapor deposition system. These films were deposited away from the conventional low power regime normally used for the deposition of device quality hydrogenated amorphous silicon films. It was observed that, with the increase of applied power, there is a change in nanocrystalline phases which were embedded in the amorphous matrix of silicon. Atomic force microscopy micrographs show that these films contain nanocrystallite of 20-100 nm size. Laser Raman and photoluminescence peaks have been observed at 514 cm{sup -1} and 2.18 eV, respectively, and particle sizes were estimated using the same as 8.24 nm and 3.26 nm, respectively. It has also been observed that nanocrystallites in these films enhanced the optical bandgap and electrical conductivity.

Effect of Sn-doped on microstructural and optical properties of ZnO thin films deposited by sol-gel method

International Nuclear Information System (INIS)

Tsay, C.-Y.; Cheng, H.-C.; Tung, Y.-T.; Tuan, W.-H.; Lin, C.-K.

2008-01-01

In this study, transparent thin films of Sn-doped ZnO (ZnO:Sn) were deposited onto alkali-free glass substrates by a sol-gel method; the effect of Sn doping on crystallinity, microstructural and optical properties was investigated. The atomic percentages of dopant in ZnO-based sols were Sn/Zn = 0, 1, 2, 3, and 5 at.%. The as-deposited films were pre-heated at 300 deg. C for 10 min and then annealed in air at 500 deg. C for 1 h. The results show that Sn-doped ZnO thin films demonstrate obviously improved surface roughness, enhanced transmittance in the 400-600 nm wavelength range and reduced average crystallite size. Among all of the annealed ZnO-based films in this study, films doped with 2 at.% Sn concentration exhibited the best properties, namely an average transmittance of 90%, an RMS roughness value of 1.92 nm and a resistivity of 9.3 x 10 2 Ω-cm

Effects of surface morphology on the optical and electrical properties of Schottky diodes of CBD deposited ZnO nanostructures

Science.gov (United States)

Mwankemwa, Benard S.; Akinkuade, Shadrach; Maabong, Kelebogile; Nel, Jackie M.; Diale, Mmantsae

2018-04-01

We report on effect of surface morphology on the optical and electrical properties of chemical bath deposited Zinc oxide (ZnO) nanostructures. ZnO nanostructures were deposited on the seeded conducting indium doped tin oxide substrate positioned in three different directions in the growth solution. Field emission scanning electron microscopy was used to evaluate the morphological properties of the synthesized nanostructures and revealed that the positioning of the substrate in the growth solution affects the surface morphology of the nanostructures. The optical absorbance, photoluminescence and Raman spectroscopy of the resulting nanostructures are discussed. The electrical characterization of the Schottky diode such as barrier height, ideality factor, rectification ratios, reverse saturation current and series resistance were found to depend on the nanostructures morphology. In addition, current transport mechanism in the higher forward bias of the Schottky diode was studied and space charge limited current was found to be the dominant transport mechanism in all samples.

A Systematic Study of the Relationship among the Morphological, Structural and Photoelectrochemical Properties of ZnO Nanorods Grown Using the Microwave Chemical Bath Deposition Method

Energy Technology Data Exchange (ETDEWEB)

Oh, Sungjin; Ryu, Hyukhyun [Inje University, Gimhae (Korea, Republic of); Lee, Won-Jae [Dong-Eui University, Busan (Korea, Republic of)

2017-08-15

In this study, zinc oxide (ZnO) nanostructures were grown on a ZnO seed layer/fluorine-doped tin oxide (FTO) substrate for different growth durations ranging from 5 to 40 min using the microwave chemical bath deposition method. We studied the effect of growth duration on the morphological, structural, optical and photoelectrochemical properties of the ZnO nanostructures. From this study, we found that the photoelectrochemical properties of the ZnO nanostructures were largely affected by their morphological and structural properties. As a result, we obtained the highest photocurrent density of 0.46 mA/cm{sup 2} (at 1.5 V vs. SCE) from the sample grown for 30 min.

Structural characterization of ZnO thin films grown on various substrates by pulsed laser deposition

Czech Academy of Sciences Publication Activity Database

Novotný, Michal; Čížek, J.; Kužel, R.; Bulíř, Jiří; Lančok, Ján; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.; Anwand, W.; Brauer, G.

2012-01-01

Roč. 45, č. 22 (2012), 1-12 ISSN 0022-3727 R&D Projects: GA ČR(CZ) GAP108/11/0958; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : ZnO thin film * pulsed laser deposition * x-ray diffraction positron implantation spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.528, year: 2012 http://dx.doi.org/10.1088/0022-3727/45/22/225101

Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

International Nuclear Information System (INIS)

Park, Joong-Hyun; Han, Sang-Myeon; Park, Sang-Geun; Han, Min-Koo; Shin, Moon-Young

2006-01-01

Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiN X ) and silicon dioxide (SiO 2 ), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,λ=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiN X buffer layer is wider than SiO 2 and the maximum grain size slightly increased

Structural and optical properties of ZnO rods hydrothermally formed on polyethersulfone substrates

Energy Technology Data Exchange (ETDEWEB)

Shin, Chang Mi; Jang, Jin Tak; Kim, Chang Yong; Ryu, Hyuk Hyun [Inje University, Gimhae (Korea, Republic of); Lee, Won Jae [Dong-Eui University, Busan (Korea, Republic of); Chang, Ji Ho [Korea Maritime University, Busan (Korea, Republic of); Son, Chang Sik [Silla University, Busan (Korea, Republic of); Choi, Hee Lack [Pukyong National University, Busan (Korea, Republic of)

2012-06-15

Various unique ZnO morphologies, such as cigar-like and belt-like structures and microrod and nanorod structures, were formed on flexible polyethersulfone (PES) substrates by using a low temperature hydrothermal route. The structural properties of ZnO depended highly on the precursor concentration. The effect of a thin ZnO seed layer deposited the on PES substrate by using atomic layer deposition on the structural and the optical properties of ZnO hydrothermally grown on the ZnO seed layer/PES substrates was studied. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements were employed to analyze the characteristics of hydrothermally-grown ZnO. The diameter of the ZnO nanorods grown on the ZnO seed layer/PES substrates increased with increasing precursor concentration from 0.025 to 0.125 M due to the Ostwald ripening process. ZnO hydrothermally-grown on the ZnO seed layer/PES substrates at a low precursor concentration showed better structural properties than ZnO formed without a seed layer. Well-formed ZnO nanorods deposited on the ZnO seed layer/PES substrates showed two PL peaks, one in the ultraviolet and the other in the visible region, whereas horizontally positioned ZnO formed on the PES substrate in the absence of a seed layer emitted only one broad PL peak in the violet region. The ZnO grown on PES substrates in this work can be used as high-quality transparent electrodes for solar cells fabricated on flexible substrates.

Structural and optical properties of ZnO rods hydrothermally formed on polyethersulfone substrates

International Nuclear Information System (INIS)

Shin, Chang Mi; Jang, Jin Tak; Kim, Chang Yong; Ryu, Hyuk Hyun; Lee, Won Jae; Chang, Ji Ho; Son, Chang Sik; Choi, Hee Lack

2012-01-01

Various unique ZnO morphologies, such as cigar-like and belt-like structures and microrod and nanorod structures, were formed on flexible polyethersulfone (PES) substrates by using a low temperature hydrothermal route. The structural properties of ZnO depended highly on the precursor concentration. The effect of a thin ZnO seed layer deposited the on PES substrate by using atomic layer deposition on the structural and the optical properties of ZnO hydrothermally grown on the ZnO seed layer/PES substrates was studied. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL) measurements were employed to analyze the characteristics of hydrothermally-grown ZnO. The diameter of the ZnO nanorods grown on the ZnO seed layer/PES substrates increased with increasing precursor concentration from 0.025 to 0.125 M due to the Ostwald ripening process. ZnO hydrothermally-grown on the ZnO seed layer/PES substrates at a low precursor concentration showed better structural properties than ZnO formed without a seed layer. Well-formed ZnO nanorods deposited on the ZnO seed layer/PES substrates showed two PL peaks, one in the ultraviolet and the other in the visible region, whereas horizontally positioned ZnO formed on the PES substrate in the absence of a seed layer emitted only one broad PL peak in the violet region. The ZnO grown on PES substrates in this work can be used as high-quality transparent electrodes for solar cells fabricated on flexible substrates.

Comparison of the influence of boron and aluminium doping on the material properties of electrochemically deposited ZnO films

Energy Technology Data Exchange (ETDEWEB)

Calnan, Sonya [Helmholtz-Zentrum für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Riedel, Wiebke; Gledhill, Sophie [Helmholtz-Zentrum für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Fachbereich Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Stannowski, Bernd [Helmholtz-Zentrum für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Lux-Steiner, Martha Ch. [Helmholtz-Zentrum für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Fachbereich Physik, Freie Universitaet Berlin, Arnimallee 14, 14195 Berlin (Germany); Schlatmann, Rutger [Helmholtz-Zentrum für Materialien und Energie GmbH, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Fachbereich 1 Ingenieurwissenschaften I, University of Applied Science (HTW) Berlin, Wilhelminenhofstraße 75 A, 12459 Berlin (Germany)

2015-11-02

The effect of varying the boron and aluminium content of the starting electrolyte for extrinsically doped ZnO films grown on SnO{sub 2}:F substrates by electrochemical deposition was investigated. The ZnO:B film surface was characterized by grains with mainly hexagonal faces exposed while the exposed faces of the ZnO:Al grains were rectangular. Whereas a B{sup 3+}/Zn{sup 2+} ratio of up to 10 at.% in the electrolyte had no significant effect on the crystalline structure of the ZnO films, an Al{sup 3+}/Zn{sup 2+} ratio above 0.25 at.% increased the disorder in the crystalline structure. All the boron doped films exhibit a strong E{sub 2}-high Raman mode related to wurtzite ZnO structure but this peak was much weaker for ZnO:Al and diminished with increasing Al incorporation in the films. Exposing the films to ultra-violet light reduced their effective sheet resistance from values beyond measurement range to values between 40 and 5000 kΩ/sq for film thicknesses of 200–550 nm. Inspection of the optical spectra near the bandgap edge and the plasma edge in the mid infrared range, showed that the Al-doping resulted in a higher carrier concentration ~ 10{sup 20} cm{sup −3} than B-doping. X-ray electron spectroscopy showed that the dopant efficiency was limited by the absence of dopant atoms near the surface of all the ZnO:B films and of the lightly doped ZnO:Al and, by the formation of aluminium oxide at the surface of the more highly doped ZnO:Al films. - Highlights: • Crystalline ZnO grown by electrochemical deposition. • Comparison of influence of H{sub 3}BO{sub 3} and Al(NO{sub 3}){sub 3} as dopant sources. • Different ZnO crystalline orientation for Al and boron doping. • Film surface chemical composition suppressed electrical conductivity.

ZnO and Al doped ZnO thin films deposited by Spray Plasma: Effect of the growth time and Al doping on microstructural, optical and electrical properties

International Nuclear Information System (INIS)

Baba, Kamal; Lazzaroni, Claudia; Nikravech, Mehrdad

2015-01-01

Nanostructured zinc oxide (ZnO) and Al doped ZnO (ZnO:Al) thin films are deposited on glass substrate by the Spray Plasma technique. Zinc nitrate and aluminium nitrate are used as Zn and Al precursors, respectively. The effect of the growth time on structural and optical properties of undoped films is studied by X-ray diffraction, atomic force microscopy, and UV–Vis spectroscopy. The effect of Al doping on microstructural, optical and electrical characteristics of ZnO:Al films is also investigated. The results show that the grain size and the film thickness both increase with the growth time. The band gap of the layers varies from 3.17 to 3.24 eV depending on the thickness. The increase of the Al doping results in the enlargement of the peak (002) and the shift of its position to higher 2θ values. Average optical transmittance decreases from 90 to 65% with the growth time because of the thickness increase while there is no significant influence of the aluminium doping on the transmittance which is above 80% in most of the visible and near-IR range for all ZnO:Al films. The electrical properties characterized by Hall measurements show that all the deposited films exhibit high resistivity, between 4 and 10 4 Ω cm. The carrier concentration decreases from 2.10 19 to 2.10 13 cm −3 when the concentration of Al increases from 1.5 to 5 atm%. - Highlights: • The original Spray Plasma technique is used for ZnO and ZnO:Al thin film deposition. • Investigation of the effect of growth time and Al doping on the structural and optical properties • Increase of grain size and film thickness with the growth time • Optical transmittance decreases from 90 to 65% with the growth time and is above 80% for ZnO:Al films in UV–Vis-NIR range. • The peak position of the (002) plane is shifted to high 2θ values with Al doping.

A Comparative Study on Structural and Optical Properties of ZnO Micro-Nanorod Arrays Grown on Seed Layers Using Chemical Bath Deposition and Spin Coating Methods

Directory of Open Access Journals (Sweden)

Sibel MORKOÇ KARADENİZ

2016-11-01

Full Text Available In this study, Zinc Oxide (ZnO seed layers were prepared on Indium Tin Oxide (ITO substrates by using Chemical Bath Deposition (CBD method and Sol-gel Spin Coating (SC method. ZnO micro-nanorod arrays were grown on ZnO seed layers by using Hydrothermal Synthesis method. Seed layer effects of structural and optical properties of ZnO arrays were characterized. X-ray diffractometer (XRD, Scanning Electron Microscopy (SEM and Ultraviolet Visible (UV-Vis Spectrometer were used for analyses. ZnO micro-nanorod arrays consisted of a single crystalline wurtzite ZnO structure for each seed layer. Besides, ZnO rod arrays were grown smoothly and vertically on SC seed layer, while ZnO rod arrays were grown randomly and flower like structures on CBD seed layer. The optical absorbance peaks found at 422 nm wavelength in the visible region for both ZnO arrays. Optical bandgap values were determined by using UV-Vis measurements at 3.12 and 3.15 eV for ZnO micro-nanorod arrays on CBD seed layer and for ZnO micro-nanorod arrays on SC-seed layer respectively.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.13443

Antibacterial properties of F-doped ZnO visible light photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Podporska-Carroll, Joanna, E-mail: joannapcarroll@gmail.com [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); Myles, Adam [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin St., Dublin (Ireland); Quilty, Brid [School of Biotechnology, Dublin City University, Dublin (Ireland); McCormack, Declan E.; Fagan, Rachel [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin St., Dublin (Ireland); Hinder, Steven J. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering (DBCEE), 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Pillai, Suresh C., E-mail: Pillai.Suresh@itsligo.ie [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); Nanotechnology Research Group, Department of Environmental Science, PEM Centre, Institute of Technology Sligo, Sligo (Ireland)

2017-02-15

Highlights: • F doped ZnO nano-powders were obtained by a modified sol–gel method. • These materials were found to be effective against S. aureus and E. coli. • Enhanced visible light photocatalytic and antimicrobial properties were obtained. • The toxic effect of ZnO on bacteria can be due to the release of zinc cations. • Production of reactive oxidation species influences bacterial viability. - Abstract: Nanocrystalline ZnO photocatalysts were prepared by a sol–gel method and modified with fluorine to improve their photocatalytic anti-bacterial activity in visible light. Pathogenic bacteria such as Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) were employed to evaluate the antimicrobial properties of synthesized materials. The interaction with biological systems was assessed by analysis of the antibacterial properties of bacteria suspended in 2% (w/w) powder solutions. The F-doping was found to be effective against S. aureus (99.99% antibacterial activity) and E. coli (99.87% antibacterial activity) when irradiated with visible light. Production of reactive oxygen species is one of the major factors that negatively impact bacterial growth. In addition, the nanosize of the ZnO particles can also be toxic to microorganisms. The small size and high surface-to-volume ratio of the ZnO nanoparticles are believed to play a role in enhancing antimicrobial activity.

Optical modeling of plasma-deposited ZnO films: Electron scattering at different length scales

International Nuclear Information System (INIS)

Knoops, Harm C. M.; Loo, Bas W. H. van de; Smit, Sjoerd; Ponomarev, Mikhail V.; Weber, Jan-Willem; Sharma, Kashish; Kessels, Wilhelmus M. M.; Creatore, Mariadriana

2015-01-01

In this work, an optical modeling study on electron scattering mechanisms in plasma-deposited ZnO layers is presented. Because various applications of ZnO films pose a limit on the electron carrier density due to its effect on the film transmittance, higher electron mobility values are generally preferred instead. Hence, insights into the electron scattering contributions affecting the carrier mobility are required. In optical models, the Drude oscillator is adopted to represent the free-electron contribution and the obtained optical mobility can be then correlated with the macroscopic material properties. However, the influence of scattering phenomena on the optical mobility depends on the considered range of photon energy. For example, the grain-boundary scattering is generally not probed by means of optical measurements and the ionized-impurity scattering contribution decreases toward higher photon energies. To understand this frequency dependence and quantify contributions from different scattering phenomena to the mobility, several case studies were analyzed in this work by means of spectroscopic ellipsometry and Fourier transform infrared (IR) spectroscopy. The obtained electrical parameters were compared to the results inferred by Hall measurements. For intrinsic ZnO (i-ZnO), the in-grain mobility was obtained by fitting reflection data with a normal Drude model in the IR range. For Al-doped ZnO (Al:ZnO), besides a normal Drude fit in the IR range, an Extended Drude fit in the UV-vis range could be used to obtain the in-grain mobility. Scattering mechanisms for a thickness series of Al:ZnO films were discerned using the more intuitive parameter “scattering frequency” instead of the parameter “mobility”. The interaction distance concept was introduced to give a physical interpretation to the frequency dependence of the scattering frequency. This physical interpretation furthermore allows the prediction of which Drude models can be used in a specific

Atomic layer deposition of absorbing thin films on nanostructured electrodes for short-wavelength infrared photosensing

International Nuclear Information System (INIS)

Xu, Jixian; Sutherland, Brandon R.; Hoogland, Sjoerd; Fan, Fengjia; Sargent, Edward H.; Kinge, Sachin

2015-01-01

Atomic layer deposition (ALD), prized for its high-quality thin-film formation in the absence of high temperature or high vacuum, has become an industry standard for the large-area deposition of a wide array of oxide materials. Recently, it has shown promise in the formation of nanocrystalline sulfide films. Here, we demonstrate the viability of ALD lead sulfide for photodetection. Leveraging the conformal capabilities of ALD, we enhance the absorption without compromising the extraction efficiency in the absorbing layer by utilizing a ZnO nanowire electrode. The nanowires are first coated with a thin shunt-preventing TiO 2 layer, followed by an infrared-active ALD PbS layer for photosensing. The ALD PbS photodetector exhibits a peak responsivity of 10 −2  A W −1 and a shot-derived specific detectivity of 3 × 10 9  Jones at 1530 nm wavelength

A chemical route to room-temperature synthesis of nanocrystalline TiO2 thin films

International Nuclear Information System (INIS)

Pathan, Habib M.; Kim, Woo Young; Jung, Kwang-Deog; Joo, Oh-Shim

2005-01-01

A lot of methods are developed for the deposition of TiO 2 thin films; however, in each of these methods as-deposited films are amorphous and need further heat treatment at high temperature. In the present article, a chemical bath deposition (CBD) method was used for the preparation of TiO 2 thin films. We investigated nanocrystalline TiO 2 thin films using CBD at room temperature onto glass and ITO coated glass substrate. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The chemically synthesized films were nanocrystalline and composed of crystal grains of 2-3 nm

Photoluminescence transient study of surface defects in ZnO nanorods grown by chemical bath deposition

Science.gov (United States)

Barbagiovanni, E. G.; Strano, V.; Franzò, G.; Crupi, I.; Mirabella, S.

2015-03-01

Two deep level defects (2.25 and 2.03 eV) associated with oxygen vacancies (Vo) were identified in ZnO nanorods (NRs) grown by low cost chemical bath deposition. A transient behaviour in the photoluminescence (PL) intensity of the two Vo states was found to be sensitive to the ambient environment and to NR post-growth treatment. The largest transient was found in samples dried on a hot plate with a PL intensity decay time, in air only, of 23 and 80 s for the 2.25 and 2.03 eV peaks, respectively. Resistance measurements under UV exposure exhibited a transient behaviour in full agreement with the PL transient, indicating a clear role of atmospheric O2 on the surface defect states. A model for surface defect transient behaviour due to band bending with respect to the Fermi level is proposed. The results have implications for a variety of sensing and photovoltaic applications of ZnO NRs.

Resistive Switching Characteristics in Electrochemically Synthesized ZnO Films

Directory of Open Access Journals (Sweden)

Shuhan Jing

2015-04-01

Full Text Available The semiconductor industry has long been seeking a new kind of non-volatile memory technology with high-density, high-speed, and low-power consumption. This study demonstrated the electrochemical synthesis of ZnO films without adding any soft or hard templates. The effect of deposition temperatures on crystal structure, surface morphology and resistive switching characteristics were investigated. Our findings reveal that the crystallinity, surface morphology and resistive switching characteristics of ZnO thin films can be well tuned by controlling deposition temperature. A conducting filament based model is proposed to explain the switching mechanism in ZnO thin films.

Improving photoelectrochemical performance on quantum dots co-sensitized TiO_2 nanotube arrays using ZnO energy barrier by atomic layer deposition

International Nuclear Information System (INIS)

Zeng, Min; Zeng, Xi; Peng, Xiange; Zhu, Zhuo; Liao, Jianjun; Liu, Kai; Wang, Guizhen; Lin, Shiwei

2016-01-01

Graphical abstract: - Highlights: • The length of TNTAs has a balance between the charge recombination and the QDs loading. • The introduction of ZnO interlayer by ALD could improve the QDs absorption. • The optimal thickness of ZnO interlayer is 1.5 nm prepared by 10 cycles ALD. - Abstract: PbS and CdS quantum dots (QDs) have been deposited onto TiO_2 nanotube arrays (TNTAs) in turn via a sonication-assisted successive ionic layer adsorption and reaction method. This method could uniformly decorate TNTAs with QDs, avoiding QDs aggregation at the mouth of TiO_2 nanotube. The loading amounts of QDs on TNTAs could be controlled by adjusting the TNTAs length. Under one sun illumination, the QDs co-sensitized TNTAs (TNTAs/QDs) with the length of about 2.4 μm displayed the highest photocurrent of 4.32 mA cm"−"2, which is 27 times higher than that of the bare TNTAs. Introduction of a thin ZnO energy barrier by atomic layer deposition (ALD) between the TNTAs and QDs can further improve the photocurrent of TNTAs/QDs. And the TNTAs/QDs with 10 ALD cycles of ZnO interlayer exhibits the highest photocurrent of 5.24 mA cm"−"2 and best photoconversion efficiency of 4.9%, a more than 20% enhancement over the bare TNTAs/QDs. Such enhanced photoelectrochemical performance may be ascribed to the increased amounts of QDs on the TNTAs due to the introduction of ZnO interlayer. The benefits of ALD layers play a crucial role in development and optimization of high-performance photoelectrodes in the near future.

Electrodeposition and characterization of nanocrystalline CoNiFe films

Energy Technology Data Exchange (ETDEWEB)

Chen, Y.; Wang, Q.P. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cai, C. [School of Chemistry and chemical engineering, Ningxia University, Yinchuan 750021 (China); Yuan, Y.N. [Department of Materials and Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cao, F.H. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, Z., E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, J.Q. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016 (China)

2012-02-29

Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} films have been fabricated using cyclic voltammetry technique from the solutions containing sulfate, then characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Meanwhile, Electrochemical Impedance Spectroscopy technique has been employed to probe into the nucleation/growth behavior of Co{sub 45}Ni{sub 10}Fe{sub 24} films. The results show that, the obtained Co{sub 45}Ni{sub 10}Fe{sub 24} film possesses low coercivity of 973.3 A/m and high saturation magnetic flux density of 1.59 Multiplication-Sign 10{sup 5} A/m. Under the experimental conditions, the nucleation/growth process of Co{sub 45}Ni{sub 10}Fe{sub 24} films is mainly under activation control. With the increase of the applied cathodic potential bias, the charge transfer resistance for CoNiFe deposition decreases exponentially. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} film is obtained using cyclic voltammetry technique. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses low coercivity of 973.3 A/m. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses high saturation magnetic flux density. Black-Right-Pointing-Pointer The nucleation/growth process of CoNiFe films is mainly under activation control. Black-Right-Pointing-Pointer The charge transfer resistance for CoNiFe deposition decreases exponentially.

Photoluminescence of ZnO thin films deposited at various substrate temperatures

International Nuclear Information System (INIS)

Kao, Kuo-Sheng; Shih, Wei-Che; Ye, Wei-Tsuen; Cheng, Da-Long

2016-01-01

This study investigated surface acoustic wave devices with an Al/ZnO/Si structure for use in ultraviolet sensors. ZnO thin films were fabricated using a reactive radio frequency magnetron sputtering system. The substrate temperature of ZnO thin films can be varied to obtain highly crystalline properties. The surface morphologies and c-axis preferred orientation of the ZnO thin films were determined using scanning electron microscopy and X-ray diffraction. In addition, bright-field images of ZnO crystallization were investigated using a transmission electron microscope. From photoluminescence analysis, four peaks were obtained at 377.8, 384.9, 391.4, and 403.4 nm. Interdigital transducers of an aluminum electrode were fabricated on the ZnO/Si structure by using a direct current sputtering system and photolithography, combined with the lift-off method, thereby obtaining a surface acoustic wave device. Finally, frequency responses were measured using a network analyzer, and an illuminating test was adopted for the ultraviolet sensor, using a wavelength of 355 nm from a light-emitting diode. The sensitivities of the ultraviolet sensor were also discussed. - Highlights: • The ZnO/Si SAW devices exhibit the Rayleigh and Sezawa modes. • The crystalline of ZnO affects the EHP recombination and generation. • The PL spectrum of ZnO shows Gaussian fitting distributions. • The CTD_U_V is influenced by SAW types and ZnO film characteristics.

Photoluminescence of ZnO thin films deposited at various substrate temperatures

Energy Technology Data Exchange (ETDEWEB)

Kao, Kuo-Sheng [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China); Shih, Wei-Che [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Ye, Wei-Tsuen [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China); Cheng, Da-Long, E-mail: dlcheng@stu.edu.tw [Department of Computer and Communication, SHU-TE University, Kaohsiung, Taiwan (China)

2016-04-30

This study investigated surface acoustic wave devices with an Al/ZnO/Si structure for use in ultraviolet sensors. ZnO thin films were fabricated using a reactive radio frequency magnetron sputtering system. The substrate temperature of ZnO thin films can be varied to obtain highly crystalline properties. The surface morphologies and c-axis preferred orientation of the ZnO thin films were determined using scanning electron microscopy and X-ray diffraction. In addition, bright-field images of ZnO crystallization were investigated using a transmission electron microscope. From photoluminescence analysis, four peaks were obtained at 377.8, 384.9, 391.4, and 403.4 nm. Interdigital transducers of an aluminum electrode were fabricated on the ZnO/Si structure by using a direct current sputtering system and photolithography, combined with the lift-off method, thereby obtaining a surface acoustic wave device. Finally, frequency responses were measured using a network analyzer, and an illuminating test was adopted for the ultraviolet sensor, using a wavelength of 355 nm from a light-emitting diode. The sensitivities of the ultraviolet sensor were also discussed. - Highlights: • The ZnO/Si SAW devices exhibit the Rayleigh and Sezawa modes. • The crystalline of ZnO affects the EHP recombination and generation. • The PL spectrum of ZnO shows Gaussian fitting distributions. • The CTD{sub UV} is influenced by SAW types and ZnO film characteristics.

Influence of surface defects in ZnO thin films on its biosensing response characteristic

Energy Technology Data Exchange (ETDEWEB)

Saha, Shibu; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

2011-09-15

Highly c-axis oriented zinc oxide (ZnO) thin films deposited by rf magnetron sputtering under varying processing pressure (20-50 mT) in a reactive gas mixture of argon and oxygen were studied for biosensing application. The as-deposited ZnO thin films were in a state of compressive stress having defects related to interstitial Zn and antisite oxygen. Glucose oxidase has been chosen as the model enzyme in the present study and was immobilized on the surface of ZnO thin films deposited on indium tin oxide coated Corning Glass substrate. The studies reveal a correlation between the biosensing characteristic and the presence of defects in the ZnO films. The ZnO films deposited under high pressure (50 mT) are found to be more sensitive for biosensing application due to availability of more surface area for effective immobilization of biomolecules and exhibits a suitable microenvironment with good electron transfer characteristic. The obtained results highlight the importance of desired microstate besides availability of suitable native defects in the ZnO thin film for exhibiting enhanced biosensing response.

Influence of surface defects in ZnO thin films on its biosensing response characteristic

International Nuclear Information System (INIS)

Saha, Shibu; Gupta, Vinay

2011-01-01

Highly c-axis oriented zinc oxide (ZnO) thin films deposited by rf magnetron sputtering under varying processing pressure (20-50 mT) in a reactive gas mixture of argon and oxygen were studied for biosensing application. The as-deposited ZnO thin films were in a state of compressive stress having defects related to interstitial Zn and antisite oxygen. Glucose oxidase has been chosen as the model enzyme in the present study and was immobilized on the surface of ZnO thin films deposited on indium tin oxide coated Corning Glass substrate. The studies reveal a correlation between the biosensing characteristic and the presence of defects in the ZnO films. The ZnO films deposited under high pressure (50 mT) are found to be more sensitive for biosensing application due to availability of more surface area for effective immobilization of biomolecules and exhibits a suitable microenvironment with good electron transfer characteristic. The obtained results highlight the importance of desired microstate besides availability of suitable native defects in the ZnO thin film for exhibiting enhanced biosensing response.

Catalytic growth of ZnO nanostructures by r.f. magnetron sputtering

Directory of Open Access Journals (Sweden)

Arroyo-Hernández María

2011-01-01

Full Text Available Abstract The catalytic effect of gold seed particles deposited on a substrate prior to zinc oxide (ZnO thin film growth by magnetron sputtering was investigated. For this purpose, selected ultra thin gold layers, with thicknesses close to the percolation threshold, are deposited by thermal evaporation in ultra high vacuum (UHV conditions and subsequently annealed to form gold nanodroplets. The ZnO structures are subsequently deposited by r.f. magnetron sputtering in a UHV chamber, and possible morphological differences between the ZnO grown on top of the substrate and on the gold are investigated. The results indicate a moderate catalytic effect for a deposited gold underlayer of 4 nm, quite close to the gold thin film percolation thickness.

Hydrogen content and density in nanocrystalline carbon films of a predominant diamond character

International Nuclear Information System (INIS)

Hoffman, A.; Heiman, A.; Akhvlediani, R.; Lakin, E.; Zolotoyabko, E.; Cyterman, C.

2003-01-01

Nanocrystalline carbon films possessing a prevailing diamond or graphite character, depending on substrate temperature, can be deposited from a methane hydrogen mixture by the direct current glow discharge plasma chemical vapor deposition method. While at a temperature of ∼880 deg. C, following the formation of a thin precursor graphitic film, diamond nucleation occurs and a nanodiamond film grows, at higher and lower deposition temperatures the films maintain their graphitic character. In this study the hydrogen content, density and nanocrystalline phase composition of films deposited at various temperatures are investigated. We aim to elucidate the role of hydrogen in nanocrystalline films with a predominant diamond character. Secondary ion mass spectroscopy revealed a considerable increase of the hydrogen concentration in the films that accompanies the growth of nanodiamond. It correlates with near edge x-ray adsorption spectroscopy measurements, that showed an appearance of spectroscopic features associated with the diamond structure, and with a substantial increase of the film density detected by x-ray reflectivity. Electron energy loss spectroscopy showed that nanocrystalline diamond films can be deposited from a CH 4 /H 2 mixture with hydrogen concentration in the 80%-95% range. For a deposition temperature of 880 deg. C, the highest diamond character of the films was found for a hydrogen concentration of 91% of H 2 . The deposition temperature plays an important role in diamond formation, strongly influencing the content of adsorbed hydrogen with an optimum at 880 deg. C. It is suggested that diamond nucleation and growth of the nanodiamond phase is driven by densification of the deposited graphitic films which results in high local compressive stresses. Nanodiamond formation is accompanied by an increase of hydrogen concentration in the films. It is suggested that hydrogen retention is critical for stabilization of nanodiamond crystallites. At lower

Growth of ZnO layers for transparent and flexible electronics

International Nuclear Information System (INIS)

Mofor, A.C.; Bakin, A.S.; Postels, B.; Suleiman, M.; Elshaer, A.; Waag, A.

2008-01-01

We have deposited and characterised ZnO on flexible and transparent plastic polymer. We employed a specially designed vapour phase growth system with elemental sources for zinc and oxygen and deposited thin ZnO films at temperatures below 400 deg. C. Basic photoluminescence characterisation confirms ZnO. Ohmic contacts were fabricated on these layers and the layers exhibit significantly high electron concentration with carrier mobility μ of up to 10.78 cm 2 V -1 s -1 . Furthermore, we show how these layers can be processed with conventional device processing techniques

Growth of ZnO layers for transparent and flexible electronics

Energy Technology Data Exchange (ETDEWEB)

Mofor, A.C.; Bakin, A.S.; Postels, B.; Suleiman, M.; Elshaer, A.; Waag, A. [Institute of Semiconductor Technology, Technical University Braunschweig, Hans-Sommer-Str. 66, D-38106 Braunschweig (Germany)

2008-02-15

We have deposited and characterised ZnO on flexible and transparent plastic polymer. We employed a specially designed vapour phase growth system with elemental sources for zinc and oxygen and deposited thin ZnO films at temperatures below 400 deg. C. Basic photoluminescence characterisation confirms ZnO. Ohmic contacts were fabricated on these layers and the layers exhibit significantly high electron concentration with carrier mobility {mu} of up to 10.78 cm{sup 2} V{sup -1} s{sup -1}. Furthermore, we show how these layers can be processed with conventional device processing techniques.

Synthesis and characterization of ZnO nanostructures on noble-metal coated substrates

Energy Technology Data Exchange (ETDEWEB)

Dikovska, A.Og. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria); Atanasova, G.B. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Avdeev, G.V. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, 1113 Sofia (Bulgaria); Nedyalkov, N.N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, Sofia 1784 (Bulgaria)

2016-06-30

Highlights: • ZnO nanostructures were fabricated on Au–Ag alloy coated silicon substrates by applying pulsed laser deposition. • Morphology of the ZnO nanostructures was related to the Au–Ag alloy content in the catalyst layer. • Increasing the Ag content in Au–Ag catalyst layer changes the morphology of the ZnO nanostructures from nanorods to nanobelts. - Abstract: In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au–Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550 °C, an oxygen pressure of 5 Pa, and a laser fluence of 2 J cm{sup −2} – process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au–Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au–Ag catalyst (Au{sub 3}Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg{sub 2}) layer resulted in the growth of a dense structure of ZnO nanobelts.

Single and multi-layered core-shell structures based on ZnO nanorods obtained by aerosol assisted chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C.; Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx

2015-07-15

Core–shell nanorod structures were prepared by a sequential synthesis using an aerosol assisted chemical vapor deposition technique. Several samples consisting of ZnO nanorods were initially grown over TiO{sub 2} film-coated borosilicate glass substrates, following the synthesis conditions reported elsewhere. Later on, a uniform layer consisting of individual Al, Ni, Ti or Fe oxides was grown onto ZnO nanorod samples forming the so-called single MO{sub x}/ZnO nanorod core–shell structures, where MO{sub x} was the metal oxide shell. Additionally, a three-layer core–shell sample was developed by growing Fe, Ti and Fe oxides alternately, onto the ZnO nanorods. The microstructure of the core–shell materials was characterized by grazing incidence X-ray diffraction, scanning and transmission electron microscopy. Energy dispersive X-ray spectroscopy was employed to corroborate the formation of different metal oxides. X-ray diffraction outcomes for single core–shell structures showed solely the presence of ZnO as wurtzite and TiO{sub 2} as anatase. For the multi-layered shell sample, the existence of Fe{sub 2}O{sub 3} as hematite was also detected. Morphological observations suggested the existence of an outer material grown onto the nanorods and further microstructural analysis by HR-STEM confirmed the development of core–shell structures in all cases. These studies also showed that the individual Al, Fe, Ni and Ti oxide layers are amorphous; an observation that matched with X-ray diffraction analysis where no apparent extra oxides were detected. For the multi-layered sample, the development of a shell consisting of three different oxide layers onto the nanorods was found. Overall results showed that no alteration in the primary ZnO core was produced during the growth of the shells, indicating that the deposition technique used herein was and it is suitable for the synthesis of homogeneous and complex nanomaterials high in quality and purity. In addition

Atomic Layer Deposition of Electron Selective SnOx and ZnO Films on Mixed Halide Perovskite: Compatibility and Performance.

Science.gov (United States)

Hultqvist, Adam; Aitola, Kerttu; Sveinbjörnsson, Kári; Saki, Zahra; Larsson, Fredrik; Törndahl, Tobias; Johansson, Erik; Boschloo, Gerrit; Edoff, Marika

2017-09-06

The compatibility of atomic layer deposition directly onto the mixed halide perovskite formamidinium lead iodide:methylammonium lead bromide (CH(NH 2 ) 2 , CH 3 NH 3 )Pb(I,Br) 3 (FAPbI 3 :MAPbBr 3 ) perovskite films is investigated by exposing the perovskite films to the full or partial atomic layer deposition processes for the electron selective layer candidates ZnO and SnO x . Exposing the samples to the heat, the vacuum, and even the counter reactant of H 2 O of the atomic layer deposition processes does not appear to alter the perovskite films in terms of crystallinity, but the choice of metal precursor is found to be critical. The Zn precursor Zn(C 2 H 5 ) 2 either by itself or in combination with H 2 O during the ZnO atomic layer deposition (ALD) process is found to enhance the decomposition of the bulk of the perovskite film into PbI 2 without even forming ZnO. In contrast, the Sn precursor Sn(N(CH 3 ) 2 ) 4 does not seem to degrade the bulk of the perovskite film, and conformal SnO x films can successfully be grown on top of it using atomic layer deposition. Using this SnO x film as the electron selective layer in inverted perovskite solar cells results in a lower power conversion efficiency of 3.4% than the 8.4% for the reference devices using phenyl-C 70 -butyric acid methyl ester. However, the devices with SnO x show strong hysteresis and can be pushed to an efficiency of 7.8% after biasing treatments. Still, these cells lacks both open circuit voltage and fill factor compared to the references, especially when thicker SnO x films are used. Upon further investigation, a possible cause of these losses could be that the perovskite/SnO x interface is not ideal and more specifically found to be rich in Sn, O, and halides, which is probably a result of the nucleation during the SnO x growth and which might introduce barriers or alter the band alignment for the transport of charge carriers.

Surface characterization of ZnO nanorods grown by chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Mbulanga, C.M., E-mail: crispin.mbulanga@nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Urgessa, Z.N.; Tankio Djiokap, S.R.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth 6031 (South Africa); Duvenhage, M.M.; Swart, H.C. [Department of Physics, University of the Free State, P.O Box 77000, Bloemfontein ZA9300 (South Africa)

2016-01-01

The surface composition of as-grown and annealed ZnO nanorods (ZNs) grown by a two-step chemical bath deposition method is investigated by the following surface-sensitive techniques: Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). The presence of H on the surface and throughout the entire thickness of ZNs is confirmed by TOF-SIMS. Based on TOF-SIMS results, the O2 XPS peak mostly observable at ~531.5 is assigned to O bound to H. Furthermore, it is found that the near surface region of as-grown ZNs is Zn-rich, and annealing at high temperature (~850 °C) removes H-related defects from the surface of ZNs and affect the balance of zinc and oxygen concentrations.

Transparent conductive ZnO layers on polymer substrates: Thin film deposition and application in organic solar cells

Energy Technology Data Exchange (ETDEWEB)

Dosmailov, M. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Leonat, L.N. [Linz Institute for Organic Solar Cells (LIOS)/Institute of Physical Chemistry, Johannes Kepler University Linz, A-4040 Linz (Austria); Patek, J. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Roth, D.; Bauer, P. [Institute of Experimental Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Scharber, M.C.; Sariciftci, N.S. [Linz Institute for Organic Solar Cells (LIOS)/Institute of Physical Chemistry, Johannes Kepler University Linz, A-4040 Linz (Austria); Pedarnig, J.D., E-mail: johannes.pedarnig@jku.at [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria)

2015-09-30

Aluminum doped ZnO (AZO) and pure ZnO thin films are grown on polymer substrates by pulsed-laser deposition and the optical, electrical, and structural film properties are investigated. Laser fluence, substrate temperature, and oxygen pressure are varied to obtain transparent, conductive, and stoichiometric AZO layers on polyethylene terephthalate (PET) that are free of cracks. At low fluence (1 J/cm{sup 2}) and low pressure (10{sup −3} mbar), AZO/PET samples of high optical transmission in the visible range, low electrical sheet resistance, and high figure of merit (FOM) are produced. AZO films on fluorinated ethylene propylene have low FOM. The AZO films on PET substrates are used as electron transport layer in inverted organic solar cell devices employing P3HT:PCBM as photovoltaic polymer-fullerene bulk heterojunction. - Highlights: • Aluminum doped and pure ZnO thin films are grown on polyethylene terephthalate. • Growth parameters laser fluence, temperature, and gas pressure are optimized. • AZO films on PET have high optical transmission and electrical conductance (FOM). • Organic solar cells on PET using AZO as electron transport layer are made. • Power conversion efficiency of these OSC devices is measured.

Controlling the resistivity gradient in chemical vapor deposition-deposited aluminum-doped zinc oxide

NARCIS (Netherlands)

Ponomarev, M. V.; Verheijen, M. A.; Keuning, W.; M. C. M. van de Sanden,; Creatore, M.

2012-01-01

Aluminum-doped ZnO (ZnO:Al) grown by chemical vapor deposition (CVD) generally exhibit a major drawback, i.e., a gradient in resistivity extending over a large range of film thickness. The present contribution addresses the plasma-enhanced CVD deposition of ZnO: Al layers by focusing on the control

Fabrication of ZnO Nanostructures with Self-cleaning Functionality

International Nuclear Information System (INIS)

Kok, K.Y.; Ng, I.K.; Nur Ubaidah Saidin; Bustaman, F.K.A.

2011-01-01

The science of biomimicry has served as a fusion point between nature and technology where one could adopt natures best solution for humans use. Lotus leaf surface, for example, possesses self cleaning capability due to its unique physical and chemical properties. In this work, we aimed to mimic these features on glass surface using ZnO nanostructures to achieve the self-cleaning functionality. A series of ZnO films were electrochemically deposited on indium-doped tin oxide (ITO) conducting glasses from different aqueous electrolytes at systematically varied deposition potentials and electrolyte conditions. The surface morphology, density, orientation and aspect ratio of the ZnO micro/nanostructures obtained were characterized using X-ray diffraction and scanning electron microscopy. Results from these studies show that lower electrolyte concentrations tend to favor one-dimensional growth of ZnO nanostructures that self-assembled into nano flowers at higher deposition temperatures. This hierarchical micro/nano-structured ZnO-modified surface exhibits super hydrophobicity with water contact angle as high as 170 degree. (author)

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.

Hybrid Organic/ZnO p-n Junctions with n-Type ZnO Grown by Atomic Layer Deposition

Science.gov (United States)

Łuka, G.; Krajewski, T.; Szczerbakow, A.; Łusakowska, E.; Kopalko, K.; Guziewicz, E.; Wachnicki, Ł.; Szczepanik, A.; Godlewski, M.; Fidelus, J. D.

2008-11-01

We report on fabrication of hybrid inorganic-on-organic thin film structures with polycrystalline zinc oxide films grown by atomic layer deposition technique. ZnO films were deposited on two kinds of thin organic films, i.e. pentacene and poly(dimethylosiloxane) elastomer with a carbon nanotube content (PDMS:CNT). Surface morphology as well as electrical measurements of the films and devices were analyzed. The current density versus voltage (I-V) characteristics of ITO/pentacene/ZnO/Au structure show a low-voltage switching phenomenon typical of organic memory elements. The I-V studies of ITO/PDMS:CNT/ZnO/Au structure indicate some charging effects in the system under applied voltages.

Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

Energy Technology Data Exchange (ETDEWEB)

Hoye, Robert L. Z., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk; MacManus-Driscoll, Judith L., E-mail: rlzh2@cam.ac.uk, E-mail: jld35@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Muñoz-Rojas, David [LMGP, University Grenoble-Alpes, CNRS, F-3800 Grenoble (France); Nelson, Shelby F. [Kodak Research Laboratories, Eastman Kodak Company, Rochester, New York 14650 (United States); Illiberi, Andrea; Poodt, Paul [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Roozeboom, Fred [Holst Centre/TNO Thin Film Technology, Eindhoven, 5656 AE (Netherlands); Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, Eindhoven, 5600 MB (Netherlands)

2015-04-01

Atmospheric pressure spatial atomic layer deposition (AP-SALD) has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

New route to the fabrication of nanocrystalline diamond films

International Nuclear Information System (INIS)

Varshney, Deepak; Morell, Gerardo; Palomino, Javier; Resto, Oscar; Gil, Jennifer; Weiner, Brad R.

2014-01-01

Nanocrystalline diamond (NCD) thin films offer applications in various fields, but the existing synthetic approaches are cumbersome and destructive. A major breakthrough has been achieved by our group in the direction of a non-destructive, scalable, and economic process of NCD thin-film fabrication. Here, we report a cheap precursor for the growth of nanocrystalline diamond in the form of paraffin wax. We show that NCD thin films can be fabricated on a copper support by using simple, commonplace paraffin wax under reaction conditions of Hot Filament Chemical Vapor Deposition (HFCVD). Surprisingly, even the presence of any catalyst or seeding that has been conventionally used in the state-of-the-art is not required. The structure of the obtained films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectroscopy and electron energy-loss spectroscopy recorded at the carbon K-edge region confirm the presence of nanocrystalline diamond. The process is a significant step towards cost-effective and non-cumbersome fabrication of nanocrystalline diamond thin films for commercial production

Improving photoelectrochemical performance on quantum dots co-sensitized TiO{sub 2} nanotube arrays using ZnO energy barrier by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Zeng, Min [Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China); Zeng, Xi [College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming, 650500 (China); Peng, Xiange; Zhu, Zhuo; Liao, Jianjun; Liu, Kai; Wang, Guizhen [Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China); Lin, Shiwei, E-mail: linsw@hainu.edu.cn [Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China)

2016-12-01

Graphical abstract: - Highlights: • The length of TNTAs has a balance between the charge recombination and the QDs loading. • The introduction of ZnO interlayer by ALD could improve the QDs absorption. • The optimal thickness of ZnO interlayer is 1.5 nm prepared by 10 cycles ALD. - Abstract: PbS and CdS quantum dots (QDs) have been deposited onto TiO{sub 2} nanotube arrays (TNTAs) in turn via a sonication-assisted successive ionic layer adsorption and reaction method. This method could uniformly decorate TNTAs with QDs, avoiding QDs aggregation at the mouth of TiO{sub 2} nanotube. The loading amounts of QDs on TNTAs could be controlled by adjusting the TNTAs length. Under one sun illumination, the QDs co-sensitized TNTAs (TNTAs/QDs) with the length of about 2.4 μm displayed the highest photocurrent of 4.32 mA cm{sup −2}, which is 27 times higher than that of the bare TNTAs. Introduction of a thin ZnO energy barrier by atomic layer deposition (ALD) between the TNTAs and QDs can further improve the photocurrent of TNTAs/QDs. And the TNTAs/QDs with 10 ALD cycles of ZnO interlayer exhibits the highest photocurrent of 5.24 mA cm{sup −2} and best photoconversion efficiency of 4.9%, a more than 20% enhancement over the bare TNTAs/QDs. Such enhanced photoelectrochemical performance may be ascribed to the increased amounts of QDs on the TNTAs due to the introduction of ZnO interlayer. The benefits of ALD layers play a crucial role in development and optimization of high-performance photoelectrodes in the near future.

Polyelectrolyte-assisted preparation and characterization of nanostructured ZnO thin films

Energy Technology Data Exchange (ETDEWEB)

Jia, Shijun

2005-05-15

The present work focuses on the synthesis and characterization of nanostructured ZnO thin films onto silicon wafers modified by self-assembled-monolayers via chemical bath deposition. Two precursor solutions were designed and used for the film deposition, in which two different polymers were introduced respectively to control the growth of the ZnO colloidal particles in solution. ZnO films were deposited from an aqueous solution containing zinc salt and hexamethylenetetramine (HMTA) in the presence of a graft-copolymer (P (MAA{sub 0.50}-co(MAA-EO{sub 20}){sub 0.50}){sub 70}). A film-formation-diagram was established based on the results obtained by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which describes the influence of the concentration of HMTA and copolymer on the ZnO film formation. According to the film morphology, film formation can be classified into three categories: (a) island-like films, (b) uniform films and (c) canyon-like films. The ZnO films annealed at temperatures of 450 C, 500 C, 600 C and 700 C were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). After annealing, the films are polycrystalline ZnO with wurtzite structure. XRD measurements indicate that with increasing annealing temperature, the average grain size increases accordingly and the crystallinity of the films is improved. Upon heating to 600 C, the ZnO films exhibit preferred orientation with c-axis normal to substrate, whereas the films annealed at 700 C even show a more explicit texture. By annealing at temperatures above 600 C the ZnO film reacts with the substrate to form an interfacial layer of Zn{sub 2}SiO{sub 4}, which grows thicker at elevated annealing temperatures. The ZnO films annealed at 600 C and 700 C show strong UV emission. Another non-aqueous solution system for ZnO thin film deposition was established, in which 2- propanol was used as a solvent and Zn(CH3COO){sub 2}.2H{sub 2}O as well as NaOH as reactants

Enhanced Doping Efficiency of Al-Doped ZnO by Atomic Layer Deposition Using Dimethylaluminum Isopropoxide as an Alternative Aluminum Precursor

NARCIS (Netherlands)

Wu, Y.; Potts, S.E.; Hermkens, P.M.; Knoops, H.C.M.; Roozeboom, F.; Kessels, W.M.M.

2013-01-01

Atomic layer deposition offers the unique opportunity to control, at the atomic level, the 3D distribution of dopants in highly uniform and conformal thin films. Here, it is demonstrated that the maximum doping efficiency of Al in ZnO can be improved from ∼10% to almost 60% using dimethylaluminum

Investigation of thin ZnO layers in view of laser desorption-ionization

Energy Technology Data Exchange (ETDEWEB)

Grechnikov, A A; Borodkov, A S [Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin Str., 119991 Moscow (Russian Federation); Georgieva, V B [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria); Alimpiev, S S; Nikiforov, S M; Simanovsky, Ya O [General Physics Institute, Russian Academy of Sciences, 38 Vavilov Str., 119991 Moscow (Russian Federation); Dimova-Malinovska, D; Angelov, O I, E-mail: lazarova@issp.bas.b [Laboratory for Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Sofia (Bulgaria)

2010-04-01

Thin zinc oxide films (ZnO) were developed as a matrix-free platform for surface assisted laser desorption-ionization (SALDI) time-of-flight mass spectrometry. The ZnO films were deposited by RF magnetron sputtering of ZnO ceramic targets in Ar atmospheres on monocrystalline silicon. The generation under UV (355 nm) laser irradiation of positive ions of atenolol, reserpine and gramicidin S from the ZnO layers deposited was studied. All analytes tested were detected as protonated molecules with no or very structure-specific fragmentation. The mass spectra obtained showed low levels of chemical background noise. All ZnO films studied exhibited high stability and good reproducibility. The detection limits for test analytes are in the 10 femtomol range.

Optical and electrical properties of transparent conducting B-doped ZnO thin films prepared by various deposition methods

International Nuclear Information System (INIS)

Nomoto, Jun-ichi; Miyata, Toshihiro; Minami, Tadatsugu

2011-01-01

B-doped ZnO (BZO) thin films were prepared with various thicknesses up to about 500 nm on glass substrates at 200 deg. C by dc or rf magnetron sputtering deposition, pulsed laser deposition (PLD), and vacuum arc plasma evaporation (VAPE) methods. Resistivities of 4-6 x 10 -4 Ω cm were obtained in BZO thin films prepared with a B content [B/(B + Zn) atomic ratio] around 1 at. % by PLD and VAPE methods: Hall mobilities above 40 cm 2 /Vs and carrier concentrations on the order of 10 20 cm -3 . All 500-nm-thick-BZO thin films prepared with a resistivity on the order of 10 -3 -10 -4 Ω cm exhibited an averaged transmittance above 80% in the wavelength range of 400-1100 nm. The resistivity in BZO thin films prepared with a thickness below about 500 nm was found to increase over time with exposure to various high humidity environments. In heat-resistance tests, the resistivity stability of BZO thin films was found to be nearly equal to that of Ga-doped ZnO thin films, so these films were judged suitable for use as a transparent electrode for thin-film solar cells.

Effects of the annealing duration of the ZnO buffer layer on structural and optical properties of ZnO rods grown by a hydrothermal process

Energy Technology Data Exchange (ETDEWEB)

Shin, C.M.; Lee, J.Y.; Heo, J.H.; Park, J.H.; Kim, C.R. [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, H., E-mail: hhryu@inje.ac.kr [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Chang, J.H. [Major of Nano Semiconductor, Korea Maritime University, 1 Dongsam-dong, Yeongdo-Ku, Busan 606-791 (Korea, Republic of); Son, C.S. [Department of Electronic Materials Engineering, Silla University, Gwaebeop-dong, Sasang-gu, Busan 617-736 (Korea, Republic of); Lee, W.J. [Department of Nano Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of); Tan, S.T. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Zhao, J.L. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Sun, X.W. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

2009-07-30

In this study, the effects of the annealing duration of a zinc oxide (ZnO) buffer layer on structural and optical properties of ZnO rods grown by a hydrothermal process are discussed. A ZnO buffer layer was deposited on p-type Si (1 1 1) substrates by the metal organic chemical vapor deposition (MOCVD) method. After that, ZnO rods were grown on the ZnO-buffer/Si (1 1 1) substrate by a hydrothermal process. In order to determine the optimum annealing duration of the buffer layer for the growth of ZnO rods, durations ranging from 0.5 to 30 min were tried. The morphology and crystal structure of the ZnO/ZnO-buffer/Si (1 1 1) were measured by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The optical properties were investigated by photoluminescence (PL) measurement.

Hybrid electroluminescent device based on MEH-PPV and ZnO

Energy Technology Data Exchange (ETDEWEB)

Hewidy, Dina; Gadallah, A.-S.; Fattah, G. Abdel

2017-02-15

Hybrid organic/inorganic electroluminescent device based on the structure of glass/ITO/PEDOT:PSS/MEH-PPV/ZnO/ZnO submicrorods/Al has been manufactured. Spin coating has been used to deposit both PEDOT:PSS and MEH-PPV. Two-step process has been used to synthesis ZnO submicrorods, namely, spin coating and chemical bath deposition. Changing the dimensions of the ZnO submicrorods in this layer structure has been investigated to improve the performance of the organic/inorganic electroluminescence device. Such layer structure provides electroluminescence with narrow emission bands due to a high gain with this structure. X-ray diffraction patterns and scanning electron microscope images show that ZnO submicrorods have hexagon structure. Current-voltage curve for the structure has been reported. Electroluminescence curves (electroluminescence intensity versus wavelength) at different bias voltages have been presented and these results show narrowing in full width at half maximum in the spectra at high current density compared to photoluminescence excitation. The narrowing in the spectrum has been explained. - Highlights: • Manufacturing of MEH-PPV and ZnO electroluminescent device has been reported. • Spin coating and chemical bath deposition have been used for preparation of ZnO. • SEM images and X-ray diffraction of ZnO have been presented. • Current-voltage curves and electroluminescent measurements have been reported.

Atomic layer deposition of absorbing thin films on nanostructured electrodes for short-wavelength infrared photosensing

Energy Technology Data Exchange (ETDEWEB)

Xu, Jixian; Sutherland, Brandon R.; Hoogland, Sjoerd; Fan, Fengjia; Sargent, Edward H., E-mail: ted.sargent@utoronto.ca [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); Kinge, Sachin [Advanced Technology, Materials and Research, Research and Development, Hoge Wei 33- Toyota Technical Centre, B-1930 Zaventem (Belgium)

2015-10-12

Atomic layer deposition (ALD), prized for its high-quality thin-film formation in the absence of high temperature or high vacuum, has become an industry standard for the large-area deposition of a wide array of oxide materials. Recently, it has shown promise in the formation of nanocrystalline sulfide films. Here, we demonstrate the viability of ALD lead sulfide for photodetection. Leveraging the conformal capabilities of ALD, we enhance the absorption without compromising the extraction efficiency in the absorbing layer by utilizing a ZnO nanowire electrode. The nanowires are first coated with a thin shunt-preventing TiO{sub 2} layer, followed by an infrared-active ALD PbS layer for photosensing. The ALD PbS photodetector exhibits a peak responsivity of 10{sup −2} A W{sup −1} and a shot-derived specific detectivity of 3 × 10{sup 9} Jones at 1530 nm wavelength.

Area-Selective ZnO Thin Film Deposition on Variable Microgap Electrodes and Their Impact on UV Sensing

Directory of Open Access Journals (Sweden)

Q. Humayun

2013-01-01

Full Text Available ZnO thin films were deposited on patterned gold electrodes using the sol-gel spin coating technique. Conventional photolithography process was used to obtain the variable microgaps of 30 and 43 μm in butterfly topology by using zero-gap chrome mask. The structural, morphological, and electrical properties of the deposited thin films were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, and Keithley SourceMeter, respectively. The current-voltage (I-V characterization was performed to investigate the effect of UV light on the fabricated devices. The ZnO fabricated sensors showed a photo to dark current (Iph/Id ratios of 6.26 for 30 μm and 5.28 for 43 μm gap electrodes spacing, respectively. Dynamic responses of both fabricated sensors were observed till 1V with good reproducibility. At the applied voltage of 1 V, the response time was observed to be 4.817 s and 3.704 s while the recovery time was observed to be 0.3738 s and 0.2891 s for 30 and 43 μm gaps, respectively. The signal detection at low operating voltages suggested that the fabricated sensors could be used for miniaturized devices with low power consumption.

Room temperature ferromagnetism in Cu doped ZnO

Science.gov (United States)

Ali, Nasir; Singh, Budhi; Khan, Zaheer Ahmed; Ghosh, Subhasis

2018-05-01

We report the room temperature ferromagnetism in 2% Cu doped ZnO films grown by RF magnetron sputtering in different argon and oxygen partial pressure. X-ray photoelectron spectroscopy was used to ascertain the oxidation states of Cu in ZnO. The presence of defects within Cu-doped ZnO films can be revealed by electron paramagnetic resonance. It has been observed that saturated magnetic moment increase as we increase the zinc vacancies during deposition.

Admittance spectroscopy of spray-pyrolyzed ZnO film

International Nuclear Information System (INIS)

Kavasoglu, Nese; Kavasoglu, A. Sertap

2008-01-01

A ZnO film was deposited using the spray pyrolysis method. The admittance spectroscopy method was used to establish the contributions to electrical behavior from grains, grain boundaries, and electrodes of film. Proper equivalent electrical circuit of a ZnO film composed of a single parallel resistor, capacitor, and inductor network connected with a series resistance was proposed. Moreover, we displayed metal-semiconductor transition (MST) in the ZnO film via admittance spectroscopy

Nanocrystalline magnetite thin films grown by dual ion-beam sputtering

International Nuclear Information System (INIS)

Prieto, Pilar; Ruiz, Patricia; Ferrer, Isabel J.; Figuera, Juan de la; Marco, José F.

2015-01-01

Highlights: • We have grown tensile and compressive strained nanocrystalline magnetite thin films by dual ion beam sputtering. • The magnetic and thermoelectric properties can be controlled by the deposition conditions. • The magnetic anisotropy depends on the crystalline grain size. • The thermoelectric properties depend on the type of strain induced in the films. • In plane uniaxial magnetic anisotropy develops in magnetite thin films with grain sizes ⩽20 nm. - Abstract: We have explored the influence of an ion-assisted beam in the thermoelectric and magnetic properties of nanocrystalline magnetite thin films grown by ion-beam sputtering. The microstructure has been investigated by XRD. Tensile and compressive strained thin films have been obtained as a function of the parameters of the ion-assisted beam. The evolution of the in-plane magnetic anisotropy was attributed to crystalline grain size. In some films, magneto-optical Kerr effect measurements reveal the existence of uniaxial magnetic anisotropy induced by the deposition process related with a small grain size (⩽20 nm). Isotropic magnetic properties have observed in nanocrystalline magnetite thin film having larger grain sizes. The largest power factor of all the films prepared (0.47 μW/K 2 cm), obtained from a Seebeck coefficient of −80 μV/K and an electrical resistivity of 13 mΩ cm, is obtained in a nanocrystalline magnetite thin film with an expanded out-of-plane lattice and with a grain size ≈30 nm

Effects of buffer layer annealing temperature on the structural and optical properties of hydrothermal grown ZnO

Energy Technology Data Exchange (ETDEWEB)

Zhao, X.Q.; Kim, C.R.; Lee, J.Y.; Heo, J.H.; Shin, C.M. [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, H., E-mail: hhryu@inje.ac.kr [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Chang, J.H. [Major of Nano Semiconductor, Korea Maritime University, 1 Dongsam-dong, Yeongdo-Ku, Busan 606-791 (Korea, Republic of); Lee, H.C. [Department of Mechatronics Engineering, Korea Maritime University, 1 Dongsam-dong, Yeongdo-Ku, Busan 606-791 (Korea, Republic of); Son, C.S. [Department of Electronic Materials Engineering, Silla University, Gwaebeop-dong, Sasang-gu, Busan 617-736 (Korea, Republic of); Lee, W.J. [Department of Nano Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of); Jung, W.G. [School of Advanced Materials Engineering, Kookmin University, 861-1 Jeongneung-dong, Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Tan, S.T. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Zhao, J.L. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Sun, X.W. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

2009-02-01

ZnO was deposited on bare Si(1 0 0), as-deposited, and annealed ZnO/Si(1 0 0) substrates by hydrothermal synthesis. The effects of a ZnO buffer layer and its thermal annealing on the properties of the ZnO deposited by hydrothermal synthesis were studied. The grain size and root mean square (RMS) roughness values of the ZnO buffer layer increased after thermal annealing of the buffer layer. The effect of buffer layer annealing temperature on the structural and optical properties was investigated by photoluminescence, X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Hydrothermal grown ZnO deposited on ZnO/Si(1 0 0) annealed at 750 deg. C with the concentration of 0.3 M exhibits the best structural and optical properties.

Photocatalytic removal of NO and HCHO over nanocrystalline Zn2SnO4 microcubes for indoor air purification

International Nuclear Information System (INIS)

Ai Zhihui; Lee Shuncheng; Huang Yu; Ho Wingkei; Zhang Lizhi

2010-01-01

Nanocrystalline Zn 2 SnO 4 microcubes were hydrothermally synthesized and systematically characterized by XRD, SEM, TEM, XPS, N 2 adsorption-desorption, and UV-vis DRS analysis. The resulting Zn 2 SnO 4 microcubes with the edge size ranging from 0.8 to 1.2 μm were composed of numerous nanoparticles with size of 10-20 nm, and their optical band gap energy was estimated to be 3.25 eV from the UV-vis diffuse reflectance spectra. On degradation of nitrogen monoxide (NO) and formaldehyde (HCHO) at typical concentrations for indoor air quality, these nanocrystalline Zn 2 SnO 4 microcubes exhibited superior photocatalytic activity to the hydrothermally synthesized ZnO, SnO 2 , and Degussa TiO 2 P25, as well as C doped TiO 2 under UV-vis light irradiation. This enhanced photocatalytic activity of the nanocrystalline Zn 2 SnO 4 microcubes was attributed to their bigger surface areas, smaller particle size, special porous structures, and special electronic configuration. The nanocrystalline Zn 2 SnO 4 microcubes were chemically stable as there was no obvious deactivation during the multiple photocatalytic reactions. This work presents a promising approach for scaling-up industrial production of Zn 2 SnO 4 nanostructures and suggests that the synthesized nanocrystalline Zn 2 SnO 4 microcubes are promising photocatalysts for indoor air purification.

Local transport properties, morphology and microstructure of ZnO decorated SiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Van Nostrand, Joseph E [Air Force Research Laboratory, Information Directorate, Rome, NY (United States); Cortez, Rebecca [Union College, Schenectady, NY (United States); Rice, Zachary P; Cady, Nathaniel C; Bergkvist, Magnus, E-mail: Joseph.VanNostrand@rl.af.mil [Albany College of Nanoscale Science and Engineering, Albany, NY (United States)

2010-10-15

We report on a novel, surfactant free method for achieving nanocrystalline ZnO decoration of an SiO{sub 2} nanoparticle at ambient temperature. The size distributions of the naked and decorated SiO{sub 2} nanoparticles are measured by means of dynamic light scattering, and a monodisperse distribution is observed for each. The morphology and microstructure of the nanoparticles are explored using atomic force microscopy and high resolution transmission electron microscopy. Investigation of the optical properties of the ZnO decorated SiO{sub 2} nanoparticles shows absorption at 350 nm. This blue shift in absorption as compared to bulk ZnO is shown to be consistent with quantum confinement effects due to the small size of the ZnO nanocrystals. Finally, the local electronic transport properties of the nanoparticles are explored by scanning conductance atomic force microscopy. A memristive hysteresis in the transport properties of the individual ZnO decorated SiO{sub 2} nanoparticles is observed. Optical absorption measurements suggest the presence of oxygen vacancies, whose migration and annihilation appear to contribute to the dynamic conduction properties of the ZnO decorated nanoparticles. We believe this to be the first demonstration of a ZnO decorated SiO{sub 2} nanoparticle, and this represents a simple yet powerful way of achieving the optical and electrical properties of ZnO in combination with the simplicity of SiO{sub 2} synthesis.

Impact of first-step potential and time on the vertical growth of ZnO nanorods on ITO substrate by two-step electrochemical deposition

International Nuclear Information System (INIS)

Kim, Tae Gyoum; Jang, Jin-Tak; Ryu, Hyukhyun; Lee, Won-Jae

2013-01-01

Highlights: •We grew vertical ZnO nanorods on ITO substrate using a two-step continuous potential process. •The nucleation for the ZnO nanorods growth was changed by first-step potential and duration. •The vertical ZnO nanorods were well grown when first-step potential was −1.2 V and 10 s. -- Abstract: In this study, we analyzed the growth of ZnO nanorods on an ITO (indium doped tin oxide) substrate by electrochemical deposition using a two-step, continuous potential process. We examined the effect of changing the first-step potential as well as the first-step duration on the morphological, structural and optical properties of ZnO nanorods, measured via using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and photoluminescence (PL), respectively. As a result, vertical ZnO nanorods were grown on ITO substrate without the need for a template when the first-step potential was set to −1.2 V for a duration of 10 s, and the second-step potential was set to −0.7 V for a duration of 1190 s. The ZnO nanorods on this sample showed the highest XRD (0 0 2)/(1 0 0) peak intensity ratio and the highest PL near band edge emission to deep level emission peak intensity ratio (NBE/DLE). In this study, the nucleation for vertical ZnO nanorod growth on an ITO substrate was found to be affected by changes in the first-step potential and first-step duration

Ultrathin ZnO interfacial passivation layer for atomic layer deposited ZrO2 dielectric on the p-In0.2Ga0.8As substrate

Science.gov (United States)

Liu, Chen; Lü, Hongliang; Yang, Tong; Zhang, Yuming; Zhang, Yimen; Liu, Dong; Ma, Zhenqiang; Yu, Weijian; Guo, Lixin

2018-06-01

Interfacial and electrical properties were investigated on metal-oxidesemiconductor capacitors (MOSCAPs) fabricated with bilayer ZnO/ZrO2 films by atomic layer deposition (ALD) on p-In0.2Ga0.8As substrates. The ZnO passivated In0.2Ga0.8As MOSCAPs have exhibited significantly improved capacitance-voltage (C-V) characteristics with the suppressed "stretched out" effect, increased accumulation capacitance and reduced accumulation frequency dispersion as well as the lower gate leakage current. In addition, the interface trap density (Dit) estimated by the Terman method was decreased dramatically for ZnO passivated p-In0.2Ga0.8As. The inherent mechanism is attributed to the fact that an ultrathin ZnO IPL employed by ALD prior to ZrO2 dielectric deposition can effectively suppress the formation of defect-related low-k oxides and As-As dimers at the interface, thus effectively improving the interface quality by largely removing the border traps aligned near the valence band edge of the p-In0.2Ga0.8As substrate.

Design and investigation of properties of nanocrystalline diamond optical planar waveguides.

Science.gov (United States)

Prajzler, Vaclav; Varga, Marian; Nekvindova, Pavla; Remes, Zdenek; Kromka, Alexander

2013-04-08

Diamond thin films have remarkable properties comparable with natural diamond. Because of these properties it is a very promising material for many various applications (sensors, heat sink, optical mirrors, chemical and radiation wear, cold cathodes, tissue engineering, etc.) In this paper we report about design, deposition and measurement of properties of optical planar waveguides fabricated from nanocrystalline diamond thin films. The nanocrystalline diamond planar waveguide was deposited by microwave plasma enhanced chemical vapor deposition and the structure of the deposited film was studied by scanning electron microscopy and Raman spectroscopy. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 632.8 nm, 964 nm, 1 310 nm and 1 550 nm wavelengths. Waveguiding properties were examined by prism coupling technique and it was found that the diamond based planar optical element guided one fundamental mode for all measured wavelengths. Values of the refractive indices of our NCD thin film measured at various wavelengths were almost the same as those of natural diamond.

Morphological transition of ZnO nanostructures influenced by magnesium doping

International Nuclear Information System (INIS)

Premkumar, T.; Zhou, Y.S.; Gao, Y.; Baskar, K.; Jiang, L.; Lu, Y.F.

2012-01-01

Wurtzite zinc oxide (ZnO) nanochains have been synthesized through high-pressure pulsed laser deposition. The chain-like ZnO nanostructures were obtained from magnesium (Mg) doped ZnO targets, whereas vertically aligned nanorods were obtained from primitive ZnO targets. The Mg doping has influenced the morphological transition of ZnO nanostructures from nanorods to nanochains. The field emission scanning electron microscope images revealed the growth of beaded ZnO nanochains. The ZnO nanochains of different diameters 40 and 120 nm were obtained. The corresponding micro-Raman spectra showed strong E 2H mode of ZnO, which confirmed the good crystallinity of the nanochains. In addition to near band edge emission at 3.28 eV, ZnO nanochains show broad deep level emission at 2.42 eV than that of ZnO nanorods.

Effect of ALD surface treatment on structural and optical properties of ZnO nanorods

Energy Technology Data Exchange (ETDEWEB)

Jang, Jin-Tak [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, Hyukhyun, E-mail: hhryu@inje.ac.kr [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Lee, Won-Jae [Department of Materials and Components Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of)

2013-07-01

In this study, we report on the improvement of the optical and structural properties of ZnO nanorods using atomic layer deposition (ALD) on seed ZnO nanorods. After the initial growth of ZnO seed nanorods by hydrothermal synthesis for 1 h, a ZnO layer with a thickness of 10 nm was deposited on the initial ZnO seed nanorods using ALD. Then ZnO was further grown by hydrothermal synthesis for 4 h. The samples were characterized using room temperature photoluminescence (PL), field emission-scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). From this experiment, it was found that the ZnO nanorods with the ALD surface treatment show improved optical and structural properties when compared with the ZnO nanorods grown only by hydrothermal synthesis. The ZnO nanorods with the ALD surface treatment show about 2.7 times higher XRD (0 0 2) peak intensity, about 2.64 times higher PL NBE peak intensity, and about 3.1 times better NBE/DLE ratio than the ZnO nanorods without an ALD surface treatment.

Friction and wear behavior of nitrogen-doped ZnO thin films deposited via MOCVD under dry contact

Directory of Open Access Journals (Sweden)

U.S. Mbamara

2016-06-01

Full Text Available Most researches on doped ZnO thin films are tilted toward their applications in optoelectronics and semiconductor devices. Research on their tribological properties is still unfolding. In this work, nitrogen-doped ZnO thin films were deposited on 304 L stainless steel substrate from a combination of zinc acetate and ammonium acetate precursor by MOCVD technique. Compositional and structural studies of the films were done using Rutherford Backscattering Spectroscopy (RBS and X-ray Diffraction (XRD. The frictional behavior of the thin film coatings was evaluated using a ball-on-flat configuration in reciprocating sliding under dry contact condition. After friction test, the flat and ball counter-face surfaces were examined to assess the wear dimension and failure mechanism. Both friction behavior and wear (in the ball counter-face were observed to be dependent on the crystallinity and thickness of the thin film coatings.

Enhanced electrical properties of dual-layer channel ZnO thin film transistors prepared by atomic layer deposition

Science.gov (United States)

Li, Huijin; Han, Dedong; Dong, Junchen; Yu, Wen; Liang, Yi; Luo, Zhen; Zhang, Shengdong; Zhang, Xing; Wang, Yi

2018-05-01

The thin film transistors (TFTs) with a dual-layer channel structure combing ZnO thin layer grown at 200 °C and ZnO film grown at 120 °C by atomic layer deposition are fabricated. The dual-layer channel TFT exhibits a low leakage current of 2.8 × 10-13 A, Ion/Ioff ratio of 3.4 × 109, saturation mobility μsat of 12 cm2 V-1 s-1, subthreshold swing (SS) of 0.25 V/decade. The SS value decreases to 0.18 V/decade after the annealing treatment in O2 due to the reduction of the trap states at the channel/dielectric interface and in the bulk channel layer. The enhanced performance obtained from the dual-layer channel TFTs is due to the ability of maintaining high mobility and suppressing the increase in the off-current at the same time.

ZnO crystals obtained by electrodeposition: Statistical analysis of most important process variables

International Nuclear Information System (INIS)

Cembrero, Jesus; Busquets-Mataix, David

2009-01-01

In this paper a comparative study by means of a statistical analysis of the main process variables affecting ZnO crystal electrodeposition is presented. ZnO crystals were deposited on two different substrates, silicon wafer and indium tin oxide. The control variables were substrate types, electrolyte concentration, temperature, exposition time and current density. The morphologies of the different substrates were observed using scanning electron microscopy. The percentage of substrate area covered by ZnO deposit was calculated by computational image analysis. The design of the applied experiments was based on a two-level factorial analysis involving a series of 32 experiments and an analysis of variance. Statistical results reveal that variables exerting a significant influence on the area covered by ZnO deposit are electrolyte concentration, substrate type and time of deposition, together with a combined two-factor interaction between temperature and current density. However, morphology is also influenced by surface roughness of the substrates

Nanocrystalline sp{sup 2} and sp{sup 3} carbons: CVD synthesis and applications

Energy Technology Data Exchange (ETDEWEB)

Terranova, M. L. [Università degli Studi di Roma “Tor Vergata,” via Della Ricerca Scientifica, Dipartimento di Scienze e Tecnologie Chimiche—MinimaLab (Italy); Rossi, M. [Università degli Studi di Roma “Sapienza,” via A. Scarpa, Dipartimento di Scienze di Base e Applicate per l’Ingegneria and Centro di Ricerca per le Nanotecnologie Applicate all’Ingegneria (CNIS) (Italy); Tamburri, E., E-mail: emanuela.tamburri@uniroma2.it [Università degli Studi di Roma “Tor Vergata,” via Della Ricerca Scientifica, Dipartimento di Scienze e Tecnologie Chimiche—MinimaLab (Italy)

2016-11-15

The design and production of innovative materials based on nanocrystalline sp{sup 2}- and sp{sup 3}-coordinated carbons is presently a focus of the scientific community. We present a review of the nanostructures obtained in our labs using a series of synthetic routes, which make use of chemical vapor deposition (CVD) techniques for the selective production of non-planar graphitic nanostructures, nanocrystalline diamonds, and hybrid two-phase nanostructures.

Sparking deposited ZnO nanoparticles as double-layered photoelectrode in ZnO dye-sensitized solar cell

Energy Technology Data Exchange (ETDEWEB)

Hongsith, Kritsada [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP center), CHE, Bangkok 10400 (Thailand); Hongsith, Niyom [Thailand Center of Excellence in Physics (ThEP center), CHE, Bangkok 10400 (Thailand); School of Science, University of Phayao, Phayao 56000 (Thailand); Wongratanaphisan, Duangmanee; Gardchareon, Atcharawon; Phadungdhitidhada, Surachet [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP center), CHE, Bangkok 10400 (Thailand); Singjai, Pisith [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Choopun, Supab, E-mail: supab99@gmail.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics (ThEP center), CHE, Bangkok 10400 (Thailand)

2013-07-31

The semiconducting layers of ZnO nanoparticles (ZN), ZnO powder (ZP) and ZnO nanopowder (ZNP) were designed and fabricated for double-layered semiconducting photoelectrode in dye-sensitized solar cells (DSSCs). The under-layer was ZN, which was prepared by simple and cost-effective sparking technique onto F-doped tin oxide (FTO) glass substrate and its thickness was controlled by number of sparking cycles for 0, 10, 25, 50 and 100 rounds under atmospheric pressure. Then, ZP or ZNP was screened on to ZN to form double-layered photoelectrode. Here, the DSSC structures were FTO/double-layered ZnO/Eosin Y/electrolyte/Pt counterelectrode. The best results of DSSCs were observed with J{sub sc} of 4.71 mA/cm{sup 2} and 5.56 mA/cm{sup 2} and photoconversion efficiency of 1.11% and 1.14% at 50 sparking cycles for ZP and ZNP over-layers, respectively. The efficiency enhancement can be explained by combination effects of electron and light scattering. Moreover, the modified equation of short circuit current density was developed and effectively used to explain the efficiency enhancement. - Highlights: • Effect of under-layer thickness is investigated. • Simple and cost-effective sparking technique is used for ZnO nanoparticles. • Efficiency enhancement can be explained by both electron and light scattering. • Modified equation of short circuit current density was developed for enhancement.

Sparking deposited ZnO nanoparticles as double-layered photoelectrode in ZnO dye-sensitized solar cell

International Nuclear Information System (INIS)

Hongsith, Kritsada; Hongsith, Niyom; Wongratanaphisan, Duangmanee; Gardchareon, Atcharawon; Phadungdhitidhada, Surachet; Singjai, Pisith; Choopun, Supab

2013-01-01

The semiconducting layers of ZnO nanoparticles (ZN), ZnO powder (ZP) and ZnO nanopowder (ZNP) were designed and fabricated for double-layered semiconducting photoelectrode in dye-sensitized solar cells (DSSCs). The under-layer was ZN, which was prepared by simple and cost-effective sparking technique onto F-doped tin oxide (FTO) glass substrate and its thickness was controlled by number of sparking cycles for 0, 10, 25, 50 and 100 rounds under atmospheric pressure. Then, ZP or ZNP was screened on to ZN to form double-layered photoelectrode. Here, the DSSC structures were FTO/double-layered ZnO/Eosin Y/electrolyte/Pt counterelectrode. The best results of DSSCs were observed with J sc of 4.71 mA/cm 2 and 5.56 mA/cm 2 and photoconversion efficiency of 1.11% and 1.14% at 50 sparking cycles for ZP and ZNP over-layers, respectively. The efficiency enhancement can be explained by combination effects of electron and light scattering. Moreover, the modified equation of short circuit current density was developed and effectively used to explain the efficiency enhancement. - Highlights: • Effect of under-layer thickness is investigated. • Simple and cost-effective sparking technique is used for ZnO nanoparticles. • Efficiency enhancement can be explained by both electron and light scattering. • Modified equation of short circuit current density was developed for enhancement

Structural and interfacial defects in c-axis oriented LiNbO3 thin films grown by pulsed laser deposition on Si using Al : ZnO conducting layer

Science.gov (United States)

Shandilya, Swati; Tomar, Monika; Sreenivas, K.; Gupta, Vinay

2009-05-01

Highly c-axis oriented LiNbO3 films are deposited using pulsed laser deposition on a silicon substrate using a transparent conducting Al doped ZnO layer. X-ray diffraction and Raman spectroscopic analysis show the fabrication of single phase and oriented LiNbO3 films under the optimized deposition condition. An extra peak at 905 cm-1 was observed in the Raman spectra of LiNbO3 film deposited at higher substrate temperature and higher oxygen pressure, and attributed to the presence of niobium antisite defects in the lattice. Dielectric constant and ac conductivity of oriented LiNbO3 films deposited under the static and rotating substrate modes have been studied. Films deposited under the rotating substrate mode exhibit dielectric properties close to the LiNbO3 single crystal. The cause of deviation in the dielectric properties of the film deposited under the static substrate mode, in comparison with the bulk, are discussed in the light of the possible formation of an interdiffusion layer at the interface of the LiNbO3 film and the Al : ZnO layer.

Structural and interfacial defects in c-axis oriented LiNbO3 thin films grown by pulsed laser deposition on Si using Al : ZnO conducting layer

International Nuclear Information System (INIS)

Shandilya, Swati; Sreenivas, K; Gupta, Vinay; Tomar, Monika

2009-01-01

Highly c-axis oriented LiNbO 3 films are deposited using pulsed laser deposition on a silicon substrate using a transparent conducting Al doped ZnO layer. X-ray diffraction and Raman spectroscopic analysis show the fabrication of single phase and oriented LiNbO 3 films under the optimized deposition condition. An extra peak at 905 cm -1 was observed in the Raman spectra of LiNbO 3 film deposited at higher substrate temperature and higher oxygen pressure, and attributed to the presence of niobium antisite defects in the lattice. Dielectric constant and ac conductivity of oriented LiNbO 3 films deposited under the static and rotating substrate modes have been studied. Films deposited under the rotating substrate mode exhibit dielectric properties close to the LiNbO 3 single crystal. The cause of deviation in the dielectric properties of the film deposited under the static substrate mode, in comparison with the bulk, are discussed in the light of the possible formation of an interdiffusion layer at the interface of the LiNbO 3 film and the Al : ZnO layer.

Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

Directory of Open Access Journals (Sweden)

Robert L. Z. Hoye

2015-04-01

Full Text Available Atmospheric pressure spatial atomic layer deposition (AP-SALD has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

Synthesis of High Crystalline Al-Doped ZnO Nanopowders from Al2O3 and ZnO by Radio-Frequency Thermal Plasma

Directory of Open Access Journals (Sweden)

Min-Kyeong Song

2015-01-01

Full Text Available High crystalline Al-doped ZnO (AZO nanopowders were prepared by in-flight treatment of ZnO and Al2O3 in Radio-Frequency (RF thermal plasma. Micron-sized (~1 μm ZnO and Al2O3 powders were mixed at Al/Zn ratios of 3.3 and 6.7 at.% and then injected into the RF thermal plasma torch along the centerline at a feeding rate of 6.6 g/min. The RF thermal plasma torch system was operated at the plate power level of ~140 kVA to evaporate the mixture oxides and the resultant vapor species were condensed into solid particles by the high flow rate of quenching gas (~7000 slpm. The FE-SEM images of the as-treated powders showed that the multipod shaped and the whisker type nanoparticles were mainly synthesized. In addition, these nanocrystalline structures were confirmed as the single phase AZO nanopowders with the hexagonal wurtzite ZnO structure by the XRD patterns and FE-TEM results with the SAED image. However, the composition changes of 0.3 and 1.0 at.% were checked for the as-synthesized AZO nanopowders at Al/Zn ratios of 3.3 and 6.7 at.%, respectively, by the XRF data, which can require the adjustment of Al/Zn in the mixture precursors for the applications of high Al doping concentrations.

Piezoelectric Response Evaluation of ZnO Thin Film Prepared by RF Magnetron Sputtering

Directory of Open Access Journals (Sweden)

Cheng Da-Long

2017-01-01

Full Text Available The most important parameter of piezoelectric materials is piezoelectric coefficient (d33. In this study, the piezoelectric ZnO thin films were deposited on the SiNx/Si substrate. The 4 inches substrate is diced into 8 cm× 8 cm piece. During the deposition process, a zinc target (99.999 wt% of 2 inches diameter was used. The vertical distance between the target and the substrate holder was fixed at 5 cm. The piezoelectric response of zinc oxide (ZnO thin films were obtained by using a direct measurement system. The system adopts a mini impact tip to generate an impulsive force and read out the piezoelectric signals immediately. Experimentally, a servo motor is used to produce a fixed quantity of force, for giving an impact against to the piezoelectric film. The ZnO thin films were deposited using the reactive radio frequency (RF magnetron sputtering method. The electric charges should be generated because of the material’s extrusion. This phenomenon was investigated through the oscilloscope by one shot trigger. It was apparent that all ZnO films exhibit piezoelectric responses evaluated by our measurement system, however, its exhibit a significant discrepancy. The piezoelectric responses of ZnO thin film at various deposition positions were measured and the crystal structures of the sputtering pressure were also discussed. The crystalline characteristics of ZnO thin films are investigated through the XRD and SEM. The results show the ZnO thin film exhibits good crystalline pattern and surface morphology with controlled sputtering condition. The ZnO thin films sputtered using 2 inches target present various piezoelectric responses. With the exactly related position, a best piezoelectric response of ZnO thin film can be achieved.

Low-temperature synthesis of homogeneous nanocrystalline cubic silicon carbide films

International Nuclear Information System (INIS)

Cheng Qijin; Xu, S.

2007-01-01

Silicon carbide films are fabricated by inductively coupled plasma chemical vapor deposition from feedstock gases silane and methane heavily diluted with hydrogen at a low substrate temperature of 300 deg. C. Fourier transform infrared absorption spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analyses show that homogeneous nanocrystalline cubic silicon carbide (3C-SiC) films can be synthesized at an appropriate silane fraction X[100%xsilane flow(SCCM)/silane+methane flow(SCCM)] in the gas mixture. The achievement of homogeneous nanocrystalline 3C-SiC films at a low substrate temperature of 300 deg. C is a synergy of a low deposition pressure (22 mTorr), high inductive rf power (2000 W), heavy dilution of feedstock gases silane and methane with hydrogen, and appropriate silane fractions X (X≤33%) in the gas mixture employed in our experiments

Nanostructured ZnO thin films prepared by sol–gel spin-coating

Energy Technology Data Exchange (ETDEWEB)

Heredia, E., E-mail: heredia.edu@gmail.com [UNIDEF (CONICET-MINDEF), J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Bojorge, C.; Casanova, J.; Cánepa, H. [UNIDEF (CONICET-MINDEF), J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, A. [Instituto de Física, Universidade de São Paulo, Cidade Universitária, 66318 São Paulo, SP (Brazil); Kellermann, G. [Universidade Federal do Paraná, 19044 Paraná (Brazil)

2014-10-30

Highlights: • ZnO films synthesized by sol–gel were deposited by spin-coating on flat substrates. • Structural features of ZnO films with several thicknesses were characterized by means of different techniques. • The thicknesses of different ZnO thin films were determined by means of FESEM and AFM. • The nanoporous structures of ZnO thin films were characterized by GISAXS using IsGISAXS software. • The average densities of ZnO thin films were derived from (i) the critical angle in 1D XR patterns, (ii) the angle of Yoneda peak in 2D GISAXS images, (iii) minimization of chi2 using IsGISAXS best fitting procedure. - Abstract: ZnO thin films deposited on silica flat plates were prepared by spin-coating and studied by applying several techniques for structural characterization. The films were prepared by depositing different numbers of layers, each deposition being followed by a thermal treatment at 200 °C to dry and consolidate the successive layers. After depositing all layers, a final thermal treatment at 450 °C during 3 h was also applied in order to eliminate organic components and to promote the crystallization of the thin films. The total thickness of the multilayered films – ranging from 40 nm up to 150 nm – was determined by AFM and FESEM. The analysis by GIXD showed that the thin films are composed of ZnO crystallites with an average diameter of 25 nm circa. XR results demonstrated that the thin films also exhibit a large volume fraction of nanoporosity, typically 30–40 vol.% in thin films having thicknesses larger than ∼70 nm. GISAXS measurements showed that the experimental scattering intensity is well described by a structural model composed of nanopores with shape of oblate spheroids, height/diameter aspect ratio within the 0.8–0.9 range and average diameter along the sample surface plane in the 5–7 nm range.

Structural and nanomechanical properties of nanocrystalline carbon thin films for photodetection

Energy Technology Data Exchange (ETDEWEB)

Rawal, Ishpal [Department of Physics, Kirorimal College, University of Delhi, Delhi 110007 (India); Panwar, Omvir Singh, E-mail: ospanwar@mail.nplindia.ernet.in; Tripathi, Ravi Kant; Chockalingam, Sreekumar [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, Avanish Kumar [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Kumar, Mahesh [Ultrafast Optoelectronics and Tetrahertz Photonics Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

2015-05-15

This paper reports the effect of helium gas pressure upon the structural, nanomechanical, and photoconductive properties of nanocrystalline carbon thin (NCT) films deposited by the filtered cathodic jet carbon arc technique. High-resolution transmission electron microscopy images confirm the nanocrystalline nature of the deposited films with different crystallite sizes (3–7 nm). The chemical structure of the deposited films is further analyzed by x-ray photoelectron spectroscopy and Raman spectroscopy, which suggest that the deposited films change from graphitelike to diamondlike, increasing in sp{sup 3} content, with a minor change in the dilution of the inert gas (helium). The graphitic character is regained upon higher dilution of the helium gas, whereupon the films exhibit an increase in sp{sup 2} content. The nanomechanical measurements show that the film deposited at a helium partial pressure of 2.2 × 10{sup −4} has the highest value of hardness (37.39 GPa) and elastic modulus (320.50 GPa). At a light intensity of 100 mW/cm{sup 2}, the NCT films deposited at 2.2 × 10{sup −4} and 0.1 mbar partial pressures of helium gas exhibit good photoresponses of 2.2% and 3.6%, respectively.

Enhanced photocatalytic performance of ZnO nanostructures by electrochemical hybridization with graphene oxide

Science.gov (United States)

Pruna, A.; Wu, Z.; Zapien, J. A.; Li, Y. Y.; Ruotolo, A.

2018-05-01

Synthesis of zinc oxide (ZnO) nanostructures is reported by electrochemical deposition from an aqueous electrolyte in presence of graphene oxide (GO) with varying oxidation degree. The properties of hybrids were investigated by scanning electron microscopy, X-ray diffraction, Raman, Fourier-Transform Infrared and X-ray photoelectron spectroscopy techniques and photocatalytic measurements. The results indicated the electrodeposition of ZnO in presence of GO with increased oxygen content led to marked differences in the morphology while Raman measurements indicated an increased defect level both in the ZnO and the electrochemically reduced GO (ErGO) within the hybrids. The decrease in C/O atomic ratio of GO (from 0.79 to 0.71) employed for the electrodeposition of ZnO resulted in an increase in photocatalytic efficiency for methylene blue degradation under UV irradiation from 4-folds to 10-folds with respect to non-hybridized ZnO. The observed synergetic effect of cathodic deposition potential and oxygen content in GO towards improving the photocatalytic activity of immobilized ZnO is expected to contribute to further development of more effective deposition approaches for the preparation of high performance hybrid nanostructures.

Photoluminescence study of aligned ZnO nanorods grown using chemical bath deposition

International Nuclear Information System (INIS)

Urgessa, Z.N.; Oluwafemi, O.S.; Dangbegnon, J.K.; Botha, J.R.

2012-01-01

The photoluminescence study of self-assembled ZnO nanorods grown on a pre-treated Si substrate by a simple chemical bath deposition method at a temperature of 80 °C is hereby reported. By annealing in O 2 environment the UV emission is enhanced with diminishing deep level emission suggesting that most of the deep level emission is due to oxygen vacancies. The photoluminescence was investigated from 10 K to room temperature. The low temperature photoluminescence spectrum is dominated by donor-bound exciton. The activation energy and binding energy of shallow donors giving rise to bound exciton emission were calculated to be around 13.2 meV, 46 meV, respectively. Depending on these energy values and nature of growth environment, hydrogen is suggested to be the possible contaminating element acting as a donor.

Trapping of cubic ZnO nanocrystallites at ambient conditions

DEFF Research Database (Denmark)

Decremps, F.; Pellicer-Porres, J.; Datchi, F.

2002-01-01

Dense powder of nanocrystalline ZnO has been recovered at ambient conditions in the metastable cubic structure after a heat treatment at high pressure (15 GPa and 550 K). Combined x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) experiments have been performed to probe both long......-range order and local crystallographic structure of the recovered sample. Within uncertainty of these techniques (about 5%), all the crystallites are found to adopt the NaCl structure. From the analysis of XRD and XAS spectra, the cell volume per chemical formula unit is found to be 19.57(1) and 19...

Preparation of a Non-Polar ZnO Film on a Single-Crystal NdGaO3 Substrate by the RF Sputtering Method

Science.gov (United States)

Kashiwaba, Y.; Tanaka, Y.; Sakuma, M.; Abe, T.; Imai, Y.; Kawasaki, K.; Nakagawa, A.; Niikura, I.; Kashiwaba, Y.; Osada, H.

2018-04-01

Preparation of non-polar ZnO ( 11\\overline{2} 0 ) films on single-crystal NdGaO3 (NGO) (001) substrates was successfully achieved by the radio frequency (RF) sputtering method. Orientation, deposition rate, and surface roughness of ZnO films strongly depend on the working pressure. Characteristics of ZnO films deposited on single-crystal NGO (001) substrates were compared with those of ZnO films deposited on single-crystal sapphire ( 01\\overline{1} 2 ) substrates. An x-ray diffraction peak of the ZnO ( 11\\overline{2} 0 ) plane was observed on ZnO films deposited on single-crystal NGO (001) substrates under working pressure of less than 0.5 Pa. On the other hand, uniaxially oriented ZnO ( 11\\overline{2} 0 ) films on single-crystal sapphire ( 01\\overline{1} 2 ) substrates were observed under working pressure of 0.1 Pa. The mechanism by which the diffraction angle of the ZnO ( 11\\overline{2} 0 ) plane on single-crystal NGO (001) substrates was shifted is discussed on the basis of anisotropic stress of lattice mismatch. The deposition rate of ZnO films decreased with an increase in working pressure, and the deposition rate on single-crystal NGO (001) substrates was larger than that on single-crystal sapphire ( 01\\overline{1} 2 ) substrates. Root mean square (RMS) roughness of ZnO films increased with an increase in working pressure, and RMS roughness of ZnO films on single-crystal NGO (001) substrates was smaller than that of ZnO films on single-crystal sapphire ( 01\\overline{1} 2 ) substrates even though the film thickness on single-crystal NGO (001) substrates was greater than that on sapphire substrates. It is thought that a single-crystal NGO (001) substrate is useful for deposition of non-polar ZnO ( 11\\overline{2} 0 ) films.

Nanocrystalline CdTe thin films by electrochemical synthesis

Directory of Open Access Journals (Sweden)

Ramesh S. Kapadnis

2013-03-01

Full Text Available Cadmium telluride thin films were deposited onto different substrates as copper, Fluorine-doped tin oxide (FTO, Indium tin oxide (ITO, Aluminum and zinc at room temperature via electrochemical route. The morphology of the film shows the nanostructures on the deposited surface of the films and their growth in vertical direction. Different nanostructures developed on different substrates. The X-ray diffraction study reveals that the deposited films are nanocrystalline in nature. UV-Visible absorption spectrum shows the wide range of absorption in the visible region. Energy-dispersive spectroscopy confirms the formation of cadmium telluride.

Ultrathin ZnS and ZnO Interfacial Passivation Layers for Atomic-Layer-Deposited HfO2 Films on InP Substrates.

Science.gov (United States)

Kim, Seung Hyun; Joo, So Yeong; Jin, Hyun Soo; Kim, Woo-Byoung; Park, Tae Joo

2016-08-17

Ultrathin ZnS and ZnO films grown by atomic layer deposition (ALD) were employed as interfacial passivation layers (IPLs) for HfO2 films on InP substrates. The interfacial layer growth during the ALD of the HfO2 film was effectively suppressed by the IPLs, resulting in the decrease of electrical thickness, hysteresis, and interface state density. Compared with the ZnO IPL, the ZnS IPL was more effective in reducing the interface state density near the valence band edge. The leakage current density through the film was considerably lowered by the IPLs because the film crystallization was suppressed. Especially for the film with the ZnS IPL, the leakage current density in the low-voltage region was significantly lower than that observed for the film with the ZnO IPL, because the direct tunneling current was suppressed by the higher conduction band offset of ZnS with the InP substrate.

Effect of Eu{sup 3+} on the structure, morphology and optical properties of flower-like ZnO synthesized using chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Koao, L.F. [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba ZA9866 (South Africa); Dejene, F.B., E-mail: dejenebf@qwa.ufs.ac.za [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba ZA9866 (South Africa); Kroon, R.E. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa)

2014-03-15

The chemical bath deposition (CBD) method was used to synthesize ZnO undoped and Eu{sup 3+}-doped nanostructures. The Eu{sup 3+} concentration was varied from 0.2 to 5 mol%. The X-ray diffraction (XRD) spectra of the undoped and low concentration Eu{sup 3+} doped ZnO nanostructures correspond to the various planes of a single hexagonal ZnO phase. The estimated crystalline grain size was calculated using the XRD spectra and was found to be in the order of 47±5 nm and independent on the Eu{sup 3+} ion concentration up to 4 mol%. Scanning electron microscopy (SEM) micrographs, however, indicate that the addition of Eu{sup 3+} influences the morphology of the samples. In the UV–vis study the highest band gap energy was obtained for the undoped ZnO. The effective band gap energy of the ZnO decayed exponentially with the addition of Eu{sup 3+} up to 4 mol% where impurity phases started to appear. Although weak luminescence was observed for excitation above the bandgap at 300 nm the best results were obtained by exciting the Eu{sup 3+} directly through the {sup 7}F{sub 0}→{sup 5}L{sub 6} absorption band at 395 nm. Excitation at a wavelength of 395 nm produced the highest Eu{sup 3+} luminescence intensity without any noticeable ZnO defect emissions. The maximum luminescence intensity for this excitation was obtained for ZnO:3 mol% Eu{sup 3+} ions and luminescent quenching was observed for higher Eu concentrations. -- Highlights: • CBD was used to synthesize ZnO undoped and Eu{sup 3+}-doped nanostructures. • The powders having particles with flower-like morphology with good optical properties. • Weak luminescence for excitation above the bandgap at 300 nm. • Excitation at 395 nm produced the highest pure Eu{sup 3+} luminescence.

Influences of oxygen gas flow rate on electrical properties of Ga-doped ZnO thin films deposited on glass and sapphire substrates

International Nuclear Information System (INIS)

Makino, Hisao; Song, Huaping; Yamamoto, Tetsuya

2014-01-01

The Ga-doped ZnO (GZO) films deposited on glass and c-plane sapphire substrates have been comparatively studied in order to explore the role of grain boundaries in electrical properties. The influences of oxygen gas flow rates (OFRs) during the deposition by ion-plating were examined. The dependences of carrier concentration, lattice parameters, and characteristic of thermal desorption of Zn on the OFR showed common features between glass and sapphire substrates, however, the Hall mobility showed different behavior. The Hall mobility of GZO films on glass increased with increasing OFR of up to 15 sccm, and decreased with further increasing OFR. On the other hand, the Hall mobility of GZO films on c-sapphire increased for up to 25 sccm. The role of grain boundary in polycrystalline GZO films has been discussed. - Highlights: • Ga-doped ZnO films were deposited on glass and c-sapphire by ion-plating. • The epitaxial growth on c-sapphire was confirmed by X-ray diffraction. • Dependence of Hall mobility showed different tendency between glass and sapphire. • Grain boundaries influence transport properties at high O 2 gas flow rate

Spectroscopic ellipsometry characterization of nano-crystalline diamondfilms prepared at various substrate temperatures and pulsed plasma frequencies using microwave plasma enhanced chemical vapor deposition apparatus with linear antenna delivery

Czech Academy of Sciences Publication Activity Database

Mistrík, J.; Janíček, P.; Taylor, Andrew; Fendrych, František; Fekete, Ladislav; Jäger, Aleš; Nesládek, M.

2014-01-01

Roč. 571, č. 1 (2014), s. 230-237 ISSN 0040-6090 R&D Projects: GA ČR GA13-31783S; GA MŠk(CZ) LM2011026 Grant - others: COST Nano TP(XE) MP0901; OP VK(XE) CZ.1.07/2.3.00/20.0306 Institutional support: RVO:68378271 Keywords : nanocrystalline diamond * thin films * microwave plasma-enhanced chemical vapor deposition * pulsed plasma * low deposition temperature Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.759, year: 2014

Structure and photoluminescence properties of Ag-coated ZnO nano-needles

Energy Technology Data Exchange (ETDEWEB)

Li Xiaozhu, E-mail: Lixiaozhu1019@21cn.com [Department of Physics, Shaoguan University, Shaoguan, Guangdong 512005 (China) and Department of Physics and Key Laboratory of Acoustic and Photonic Materials and Devices of Ministry of Education, Wuhan University, Wuhan, Hubei 430072 (China); Wang Yongqian [Engineering Research Center of Nano-Geomaterials of Ministry of Education (China University of Geosciences), Wuhan, Hubei 430074 (China)

2011-05-12

Highlights: > ZnO nano-needles were synthesized by thermal oxidation. > Their surfaces were coated with Ag by pulse electro-deposition technique. > The uncoated and coated ZnO nano-needles were characterized. > The results showed that the prepared ZnO nano-needles have been coated with Ag successfully. > The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the Ag-coated ZnO nano-needles can increase the absorption of UV light. - Abstract: A large number of zinc oxide (ZnO) nano-needles were synthesized by thermal oxidation of pure zinc. The surfaces of ZnO nano-needles were coated with a layer of Ag by pulse electro-deposition technique. The uncoated and coated ZnO nano-needles were characterized by using the X-ray diffraction and the scanning electron microscope (SEM). The results showed that the uncoated samples were close-packed hexagonal structure, which showed needle-like morphology. Their average diameter is about 40 nm, lengths up to 5 {mu}m. At the same time we observed that the prepared ZnO nano-needles have been coated with Ag successfully. The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the uncoated ZnO nano-needles have two fluorescence peaks at 388 nm and 470.8 nm, respectively, the relative intensity of 143.4 and 93.61; and the Ag-coated ZnO nano-needles showed a pair of strong peaks at 387.4 nm and 405.2 nm, the relative intensity of 1366 and 1305, respectively, indicating that the Ag-coated ZnO nano-needles can increase the absorption of UV light.

Optical and electrical properties of transparent conducting B-doped ZnO thin films prepared by various deposition methods

Energy Technology Data Exchange (ETDEWEB)

Nomoto, Jun-ichi; Miyata, Toshihiro; Minami, Tadatsugu [Optoelectronic Device System R and D Center, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501 (Japan)

2011-07-15

B-doped ZnO (BZO) thin films were prepared with various thicknesses up to about 500 nm on glass substrates at 200 deg. C by dc or rf magnetron sputtering deposition, pulsed laser deposition (PLD), and vacuum arc plasma evaporation (VAPE) methods. Resistivities of 4-6 x 10{sup -4}{Omega} cm were obtained in BZO thin films prepared with a B content [B/(B + Zn) atomic ratio] around 1 at. % by PLD and VAPE methods: Hall mobilities above 40 cm{sup 2}/Vs and carrier concentrations on the order of 10{sup 20} cm{sup -3}. All 500-nm-thick-BZO thin films prepared with a resistivity on the order of 10{sup -3}-10{sup -4}{Omega} cm exhibited an averaged transmittance above 80% in the wavelength range of 400-1100 nm. The resistivity in BZO thin films prepared with a thickness below about 500 nm was found to increase over time with exposure to various high humidity environments. In heat-resistance tests, the resistivity stability of BZO thin films was found to be nearly equal to that of Ga-doped ZnO thin films, so these films were judged suitable for use as a transparent electrode for thin-film solar cells.

High power Co3O4/ZnO p–n type piezoelectric transducer

International Nuclear Information System (INIS)

Hu, Yuh-Chung; Lee, Tsung-Han; Chang, Pei-Zen; Su, Pei-Chen

2015-01-01

Enhancing the output power of piezoelectric transducer is essential in order to supply sufficient and sustainable power to wireless sensor nodes or electronic devices. In this work, a Co 3 O 4 /ZnO p–n type power piezoelectric transducer which can be operated at low frequencies has been developed by utilizing n-type semiconducting zinc oxide (ZnO) and p-type semiconducting tricobalt tetroxide (Co 3 O 4 ). We utilize ZnO to be the piezoelectric transducer and build a multi-layer (Au/Co 3 O 4 /ZnO/Ti) thin film structure. The ZnO thin film with preferred orientation along the (002) plane was deposited under optimized deposition conditions on the flexible titanium (Ti) foil with thickness of 80 μm. The Co 3 O 4 /ZnO interface forms a p–n junction and increases the difference in Fermi levels between the two electrodes, resulting in the great enhancement of output power. The measured output power of the p–n type piezoelectric transducer with optimal resistance of 100 kΩ is 10.4 μW at low operating frequency of 37 Hz, which is 10.9 times of output power of ZnO piezoelectric transducers. - Highlights: • Deposited zinc oxide performed good piezoelectric coefficient. • ZnO thin film with preferred orientation along the (002) plane was deposited. • A p–n type piezoelectric transducer with enhanced output power was fabricated. • 10.9 times increment in output power was obtained. • Increase of difference in Fermi level and p–n junction formation was explained

On performance limitations and property correlations of Al-doped ZnO deposited by radio-frequency sputtering

DEFF Research Database (Denmark)

Crovetto, Andrea; Ottsen, Tobias Sand; Stamate, Eugen

2016-01-01

-pressure regime, we find a generalized dependence of the electrical properties, grain size, texture, and Al content on compressive stress, regardless of sputtering pressure or position on the substrate. In a high-pressure regime, a porous microstructure limits the achievable resistivity and causes it to increase......The electrical properties of RF-sputtered Al-doped ZnO are often spatially inhomogeneous and strongly dependent on deposition parameters. In this work, we study the mechanisms that limit the minimum resistivity achievable under different deposition regimes. In a low- and intermediate...... over time as well. The primary cause of inhomogeneity in the electrical properties is identified as energetic particle bombardment. Inhomogeneity in oxygen content is also observed, but its effect on the electrical properties is small and limited to the carrier mobility....

The impacts of growth temperature on morphologies, compositions and optical properties of Mg-doped ZnO nanomaterials by chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Wang, X.H., E-mail: wangxh@sdju.edu.cn [School of Mechanical Engineering, Shanghai Dianji University, 1201 Jiang Chuan Road, Shanghai 200245 (China); Huang, L.Q.; Niu, L.J.; Li, R.B. [School of Mechanical Engineering, Shanghai Dianji University, 1201 Jiang Chuan Road, Shanghai 200245 (China); Fan, D.H. [Institute of Functional Materials Research, Department of Mathematics and Physics, Wuyi University, Jiangmen 529020 (China); Zhang, F.B.; Chen, Z.W.; Wang, X.; Guo, Q.X. [Department of Electrical and Electronic Engineering, Synchrotron Light Application Center, Saga University, Saga 840-8502 (Japan)

2015-02-15

Highlights: • Mg-doped ZnO nanomaterials were fabricated by chemical vapor deposition (CVD). • Growth temperature determines the characteristics of Zn{sub 1-x}Mg{sub x}O nanomaterials. • The modulation of band gap is caused by Mg addition. - Abstract: The Mg-doped ZnO (Zn{sub 1-x}Mg{sub x}O) nanomaterials with different morphologies of nanoparticles, partially opened nanowire-on-spherical shells, hemispheric shells and chain-like nanoparticles were synthesized at 750, 850, 900 and 1000 °C by a simple chemical vapor deposition. The energy dispersive X-ray (EDX) measurements indicate that Mg content increases from 2.87 at.% to 5.01 at.% with the increase of growth temperature from 750 to 1000 °C. The measurement results of X-ray diffraction (XRD) show that the (0 0 2) peaks of Zn{sub 1-x}Mg{sub x}O nanomaterials shift to higher diffraction angle with the increase of Mg content, implying that Mg{sup 2+} is substituted into Zn{sup 2+} site. The absorption spectra at room temperature exhibit that the band gap of the Mg-doped ZnO nanomaterials increases with the Mg concentration, illustrating that the modulation of band gap is caused by Mg addition. The PL measurements show that UV peak from Zn{sub 1-x}Mg{sub x}O nanomaterials is shifted towards lower wavelength side (blue shift) from 381 nm to 372 nm with the increase of the Mg dopant content. The room-temperature Raman spectra show that the crystal quality of the Zn{sub 1-x}Mg{sub x}O nanomaterials is improved with the increase of growth temperature, and the Mg dopants do not decrease the crystal quality of ZnO nanomaterials.

The effect of Cu{sup 2+} on structure, morphology and optical properties of flower-like ZnO synthesized using the chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Koao, L.F., E-mail: koaolf@qwa.ufs.ac.za [Department of Physics, University of the Free State, Qwaqwa Campus, Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, B.F. [Department of Physics, University of the Free State, Qwaqwa Campus, Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, H.C. [Department of Physics, University of the Free State, PO Box 339, Bloemfontein 9300 (South Africa)

2014-04-15

In this work undoped and Cu{sup 2+}-doped ZnO nanostructures were prepared by the chemical bath deposition (CBD) method at 80 °C. The structural, optical and luminescence properties of the undoped and Cu{sup 2+}-doped ZnO nanostructures were determined by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), UV–Visible Spectroscopy (UV) and Photoluminescence spectroscopy (PL) analyses. XRD analysis showed the sample prepared were hexagonal ZnO with grain sizes in the order of 46±1 nm. The estimated grain size was found not to dependent on the concentration of the Cu{sup 2+} ions used. The SEM analysis revealed that the shapes of the particles were flower-like and the addition of Cu{sup 2+} ions influenced the morphology of the samples. In the UV–Visible study the reflectance intensity decreased with an increase in the molar concentration of Cu{sup 2+} and there was no shift in the absorption edges. The PL analyses revealed that the highest luminescence intensity was obtained for the undoped ZnO. Thus Cu incorporated into the ZnO resulted in the change in its morphological, structural, and optical and luminescence properties.

Structural and interfacial defects in c-axis oriented LiNbO{sub 3} thin films grown by pulsed laser deposition on Si using Al : ZnO conducting layer

Energy Technology Data Exchange (ETDEWEB)

Shandilya, Swati; Sreenivas, K; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Tomar, Monika [Miranda House, University of Delhi, Delhi 110007 (India)

2009-05-07

Highly c-axis oriented LiNbO{sub 3} films are deposited using pulsed laser deposition on a silicon substrate using a transparent conducting Al doped ZnO layer. X-ray diffraction and Raman spectroscopic analysis show the fabrication of single phase and oriented LiNbO{sub 3} films under the optimized deposition condition. An extra peak at 905 cm{sup -1} was observed in the Raman spectra of LiNbO{sub 3} film deposited at higher substrate temperature and higher oxygen pressure, and attributed to the presence of niobium antisite defects in the lattice. Dielectric constant and ac conductivity of oriented LiNbO{sub 3} films deposited under the static and rotating substrate modes have been studied. Films deposited under the rotating substrate mode exhibit dielectric properties close to the LiNbO{sub 3} single crystal. The cause of deviation in the dielectric properties of the film deposited under the static substrate mode, in comparison with the bulk, are discussed in the light of the possible formation of an interdiffusion layer at the interface of the LiNbO{sub 3} film and the Al : ZnO layer.

Growth and characterization of ZnO thin films prepared by electrodeposition technique

Energy Technology Data Exchange (ETDEWEB)

Fahoume, M.; Maghfoul, O.; Aggour, M. [L.P.M.C., Faculte des Sciences, Universite Ibn Tofail, BP. 133-14000 Kenitra (Morocco); Hartiti, B. [L.P.M.A.E.R., Faculte des Sciences et Techniques, B.P. 146 Mohammedia (Morocco); Chraibi, F.; Ennaoui, A. [L.P.M., Faculte des Sciences, Universite Mohammed V, BP.1014 Rabat (Morocco)

2006-06-15

ZnO thin films were deposited on either indium tin oxide-coated glass or copper substrate by the electrodeposition process, using zinc chloride and flowing air as precursors. The effect of pH on the structural and morphological ZnO films was studied and the optimum deposition conditions have been outlined. The kinetics of the growth of the films have been investigated. We note that the rate of deposition of ZnO in an acidic solution was larger than in a basic solution. The structure of the films was studied using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The surface morphology and thickness of the films were determined using scanning electron microscopy. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure (zincite) at pH 4. The optical transmittance of ZnO decreases with varying film thickness. The optical energy bandgap was found to be 3.26eV. (author)

Orientation-dependent chemistry and band-bending of Ti on polar ZnO surfaces.

Science.gov (United States)

Borghetti, Patrizia; Mouchaal, Younes; Dai, Zongbei; Cabailh, Gregory; Chenot, Stéphane; Lazzari, Rémi; Jupille, Jacques

2017-04-19

Orientation-dependent reactivity and band-bending are evidenced upon Ti deposition (1-10 Å) on polar ZnO(0001)-Zn and ZnO(0001[combining macron])-O surfaces. At the onset of the Ti deposition, a downward band-bending was observed on ZnO(0001[combining macron])-O while no change occurred on ZnO(0001)-Zn. Combining this with the photoemission analysis of the Ti 2p core level and Zn L 3 (L 2 )M 45 M 45 Auger transition, it is established that the Ti/ZnO reaction is of the form Ti + 2ZnO → TiO 2 + 2Zn on ZnO(0001)-Zn and Ti + yZnO → TiZn x O y + (y - x)Zn on ZnO(0001[combining macron])-O. Consistently, upon annealing thicker Ti adlayers, the metallic zinc is removed to leave ZnO(0001)-Zn surfaces covered with a TiO 2 -like phase and ZnO(0001[combining macron])-O surfaces covered with a defined (Ti, Zn, O) compound. Finally, a difference in the activation temperature between the O-terminated (500 K) and Zn-terminated (700 K) surfaces is observed, which is tentatively explained by different electric fields in the space charge layer at ZnO surfaces.

Effect of plating time on growth of nanocrystalline Ni–P from ...

Indian Academy of Sciences (India)

of the crystal size increases and the number of nanocrystals decreases as seen in figure 2(f–k) (Wang et al 2003). Dense coverage of Ni–P granular deposits is seen up to 300 s with crystals size in nanometer range and hence the Ni–P coat- ings are nanocrystalline in nature. When the deposition time is increased to 1800 s ...

Correlation between structural and electrical properties of ZnO thin films

International Nuclear Information System (INIS)

Asadov, A.; Gao, W.; Li, Z.; Lee, J.; Hodgson, M.

2005-01-01

Thin ZnO films were deposited by radio frequency (r.f.) and direct current (d.c.) magnetron sputtering techniques onto glass substrates. Microstructural and electrical properties of ZnO films were studied using X-ray diffractometer (XRD), scanning electron microscope (SEM) and resistivity measurements. It was found that the size of the crystallites in the d.c. deposited films increased with increasing film thickness, while the crystallite size of r.f. deposited films remained unchanged. The d.c. deposited grains also had much stronger orientation related to the substrate than the r.f. films. XRD data indicated that the thin films with d<350 nm for r.f. and <750 nm for d.c. films have a very high degree of ZnO nonstoichiometry. This agreed well with the conductivity measurements and R(T) behaviour of the films with different resistance R. It was also found that the electrical resistivity of the samples increased exponentially with the thickness of films

Mn doping in ZnO nanoparticles: effects investigated by positron lifetime and Doppler broadening studies

Energy Technology Data Exchange (ETDEWEB)

Roy, B.; Karmakar, B.; Pal, M. [Department of Physics, University of Burdwan, Golapbag, Burdwan (India); Nambissan, P.M.G. [Saha Institute of Nuclear Physics, Kolkata (India)

2009-11-15

Positron lifetime and Doppler broadening measurements in nanocrystalline zinc oxide (ZnO) indicated the negatively charged trivacancy-type defects V{sub Zn+O+Zn} as the predominant positron trapping sites within the nanocrystallites. They got converted to neutral divacancies (V{sub Zn+O}) on doping with manganese (Mn). Further doping resulted in the reduction of the size of the nanocrystallites. At still increased doping concentrations, a new phase ZnMn{sub 2}O{sub 4} was formed. It had a normal spinel structure with positron trapping centers at some of the tetrahedral and octahedral sites. X-ray diffraction and transmission electron micro-scopy studies confirmed these findings. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Patterned hydrophobic and hydrophilic surfaces of ultra-smooth nanocrystalline diamond layers

Energy Technology Data Exchange (ETDEWEB)

Mertens, M., E-mail: michael.mertens@uni-ulm.de [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Mohr, M.; Brühne, K.; Fecht, H.J. [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Łojkowski, M.; Święszkowski, W. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Łojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw (Poland)

2016-12-30

Highlights: • Hydrophobic and hydrophilic properties on fluorine-, hydrogen- and oxygen- terminated ultra-nanocrystalline diamond films. • Micropatterned - multi-terminated layers with both hydrophobic and hydrophilic areas on one sample. • Visualization of multi-terminated surfaces by e.g. SEM and LFM. • Roughness and friction investigations on different terminated surfaces. • Smooth and biocompatible surfaces with same roughness regardless of hydrophobicity for microbiological investigations. - Abstract: In this work, we show that ultra nanocrystalline diamond (UNCD) surfaces have been modified to add them hydrophobic and hydrophilic properties. The nanocrystalline diamond films were deposited using the hot filament chemical vapor deposition (HFCVD) technique. This allows growing diamond on different substrates which can be even 3D or structured. Silicon and, for optical applications, transparent quartz glass are the preferred substrates for UNCD layers growth. Fluorine termination leads to strong hydrophobic properties as indicated by a high contact angle for water of more than 100°. Hydrogen termination shows lesser hydrophobic behavior. Hydrophilic characteristics has been realised with oxygen termination. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) measurements confirm the oxygen and fluorine- termination on the nanocrystalline diamond surface. Further, by micropatterning using photolithography, multi-terminated layers have been created with both hydrophobic and hydrophilic areas. In addition, we have shown that retermination is achieved, and the properties of the surface have been changed from hydrophobic to hydrophilic and vice versa. Micro- roughness and stress in the grown film influences slightly the wetting angle as well. The opportunity to realize local differences in hydrophobicity on nanocrystalline diamond layers, in any size or geometry, offers interesting applications for example in

Zinc oxide microcapsules obtained via a bio-inspired approach

International Nuclear Information System (INIS)

Lipowsky, Peter; Hirscher, Michael; Hoffmann, Rudolf C; Bill, Joachim; Aldinger, Fritz

2007-01-01

Hollow zinc oxide microcapsules have been synthesized by a sacrificial template route involving the chemical bath deposition of nanostructured zinc oxide thin films on sulfonate-modified polystyrene microspheres and subsequent removal of the polymer core by dissolution in a solvent or by thermolysis. Scanning electron micrographs show that uniform coating of the templates is achieved when ZnO is deposited from a solution containing zinc acetate, the polymer polyvinylpyrrolidone, and a base in methanol, and that the ZnO shells remain intact after removal of the cores. A focused ion beam is used to cut slices from the spheres and demonstrate their inner morphology and hollowness. X-ray diffraction yields evidence that the shells consist of nanocrystalline ZnO with the zincite structure

Properties of fluorine and tin co-doped ZnO thin films deposited by sol–gel method

International Nuclear Information System (INIS)

Pan, Zhanchang; Zhang, Pengwei; Tian, Xinlong; Cheng, Guo; Xie, Yinghao; Zhang, Huangchu; Zeng, Xiangfu; Xiao, Chumin; Hu, Guanghui; Wei, Zhigang

2013-01-01

Highlights: •F and Sn co-doped ZnO thin films were synthesized by sol–gel method. •The effects of different F doping concentrations were investigated. •The co-doped nanocrystals exhibit good crystal quality. •The origin of the photoluminescence emissions was discussed. •The films showed high transmittance and low resistivity. -- Abstract: Highly transparent and conducting fluorine (F) and tin (Sn) co-doped ZnO (FTZO) thin films were deposited on glass substrates by the sol–gel processing. The structure and morphology of the films are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) with various F doping concentrations. SEM images showed that the hexagonal ZnO crystals were well-arranged on the glass substrates and the HRTEM images indicated that the individual nanocrystals are highly oriented and exhibited a perfect lattice structure. Owing to its high carrier concentration and mobility, as well as good crystal quality, a minimum resistivity of 1 × 10 −3 Ω cm was obtained from the FTZO thin film with 3% F doping, and the average optical transmittance in the entire visible wavelength region was higher than 90%. The X-ray photoelectron spectroscopy (XPS) study confirmed the substitution of Zn 2+ by Sn ions and Room temperature photoluminescence (PL) observed for pure and FTZO thin films suggested the films exhibit a good crystallinity with a very low defect concentration

Synthesis of nanocrystalline Cu1-xTax composites using physical vapor deposition

International Nuclear Information System (INIS)

Savage, H.S.; Wang, H.; Rigsbee, J.M.

1993-01-01

Physical vapor deposition (PVD) processes provide the capability for creating new types of metallic, ceramic, and polymeric composites by allowing atomic-scale engineering of structure and chemistry. Because PVD processes provide the capacity for circumventing thermodynamic factors, such as solubility limits, it is possible to produce nonequilibrium alloys and materials with unique mixtures of phases. The ease by which PVD produces materials with nanocrystalline microstructures is an added benefit of these processes. This paper describes ion plating, a plasma-assisted PVD process, and its application for the development of a new class of nanoscale dispersion-strengthened Cu 1-x Ta x alloys. Copper-tantalum was selected as a model system because the extensive liquid miscibility gap and nearly zero mutual solid solubilities prevent creation of Cu-Ta alloys by conventional or rapid solidification processes. Microchemical analyses of the family of Cu 1-x Ta x alloys indicate that PVD can produce materials with any desired level of Ta. X-ray diffraction and transmission electron microscopy analyses show that the as-deposited microstructures consist generally of a Cu matrix supersaturated with Ta and containing a uniform dispersion of Ta particles with diameters below 10 nm. The Ta particles are face centered cubic (exceptionally large Ta particles, larger than ∼100 nm, are body centered cubic) and are oriented identically with the Cu matrix. Particle coarsening studies, at temperatures up to 900C and for times as long as 100 hours, indicate an extreme degree of microstructural stability. The Ta particles also appear highly effective at maintaining a submicron Cu matrix grain size even after annealing at 900C

Glancing angle deposited Al-doped ZnO nanostructures with different structural and optical properties

Energy Technology Data Exchange (ETDEWEB)

Yildiz, A., E-mail: yildizab@gmail.com [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Department of Energy Systems Engineering, Faculty of Engineering and Natural Sciences, Yıldırım Beyazıt University, Ankara (Turkey); Cansizoglu, H. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Turkoz, M. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States); Department of Electrical-Electronic Engineering, Faculty of Engineering, University of Karabuk, Karabuk (Turkey); Abdulrahman, R.; Al-Hilo, Alaa; Cansizoglu, M.F.; Demirkan, T.M.; Karabacak, T. [Department of Physics and Astronomy, University of Arkansas at Little Rock, Little Rock, AR 72204 (United States)

2015-08-31

Al-doped ZnO (AZO) nanostructure arrays with different shapes (tilted rods, vertical rods, spirals, and zigzags) were fabricated by utilizing glancing angle deposition (GLAD) technique in a DC sputter growth unit at room temperature. During GLAD, all the samples were tilted at an oblique angle of about 90° with respect to incoming flux direction. In order to vary the shapes of nanostructures, each sample was rotated at different speeds around the substrate normal axis. Rotation speed did not only affect the shape but also changed the microstructural and optical properties of GLAD AZO nanostructures. The experimental results reveal that GLAD AZO nanostructures of different shapes each have unique morphological, crystal structure, mechanical, and optical properties determined by scanning electron microscopy, X-ray diffraction, transmission, and reflectance measurements. Vertical nanorods display the largest grain size, minimum strain, lowest defect density, and highest optical transmittance compared to the other shapes. Growth dynamics of GLAD has been discussed to explain the dependence of structural and optical properties of nanostructures on the substrate rotation speed. - Highlights: • Al-doped ZnO (AZO) nanostructures with different shapes were fabricated. • They have unique morphological, crystal structure, and optical properties. • Vertical AZO nanorods show an enhanced optical transmittance.

Tuning the photovoltage of dye-sensitized solar cells based on electrodeposited ZnO

Energy Technology Data Exchange (ETDEWEB)

Oekermann, Torsten [Institute of Physical Chemistry and Electrochemistry, Leibniz Universitaet Hannover, Callinstrasse 3- 3A, 30167 Hannover (Germany); Peter, Laurence [Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Yoshida, Tsukasa [Graduate School of Engineering, Gifu University, Yanagido 1-1, Gifu 501-1193 (Japan)

2007-07-01

Nanoporous, fully crystalline ZnO films can be prepared by cathodic electrodeposition from aqueous solutions of Zn salts under the influence of structure-directing agents such as surfactants. Dye-sensitized solar cells (DSSC) based on such films have emerged as a possible alternative for nanocrystalline TiO2-based DSSC due to the very high porosity and good electron transport properties of the films. In this study, we have investigated the influence of the sensitizer dye molecules on the photovoltage of the ZnO-based DSSC. Impedance measurements show that the adsorbed dye molecules lead to a shift of the flatband potential of the ZnO. Electron pushing or withdrawing effects of the dye molecules and protonation or deprotonation of the ZnO surface are discussed as possible explanations. The shifts in the flatband potential partly explain the differences in the photovoltages caused by different dyes, however, differences in the electron injection efficiency and the blocking of electron back reaction by the dye molecules have to be taken into account, too, for a complete description.

Photoelectrochemical properties of hierarchical ZnO micro-nanostructure sensitized with Sb2S3 nanoparticles

Directory of Open Access Journals (Sweden)

Zhimin GUO

2016-02-01

Full Text Available By using electrochemical deposition method, and assisted with additions of PEG-400 and EDA, well-aligned ZnO nanorods and hierarchical ZnO micro-nanostructure are fabricated directly on indium doped tin oxide coated conducting glass (ITO substrate. The shell-core Sb2S3/ZnO nanorod structure and the shell-core hierarchical Sb2S3/ZnO micro-nanostructure are prepared by chemical bath deposition method. SEM, XRD, UV-Vis and photocurrent test are used to characterize the morphology, nanostructures and their photoelectrochemical properties. The studies show that the photocurrent on the array membranes with shell-core hierarchical Sb2S3/ZnO micro-nanostructure is apparently higher than that with shell-core Sb2S3/ZnO nanorods array.

Comparison study of V-doped ZnO thin films on polycarbonate and quartz substrates deposited by RF magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Tomoya, E-mail: tomoya@ecei.tohoku.ac.jp; Chiba, Hiroshi; Kawashima, Tomoyuki; Washio, Katsuyoshi

2016-04-30

Vanadium (V) doped ZnO (VZO) thin films were deposited on flexible polymer and quartz substrates by RF magnetron sputtering, and influences of deposition parameters of V concentration, RF power and growth temperature on resistivity, transmittance and crystallinity were investigated. For the polymer substrates, both a high heat-resistant polycarbonate (PC) film and a functional-layer-coated PC film were adopted. The resistivity decreased gradually but the transmittance was worsened with increasing V concentration. Low RF power and high growth temperature improved both transparency and conductivity. By over-coating of the functional layers, c-axis orientation was deteriorated while low-resistivity and high-transmittance characteristics were achieved. Resistivity and average visible-transmittance (wavelength = 450–800 nm) of VZO films on untreated PC and over-coated PC substrates were 0.98 mΩ cm and 83.7%, and 1.2 mΩ cm and 80.3%, respectively, at V concentration of 2 at.%, RF power of 100 W and growth temperature of 175 °C. VZO films on the polymer substrates had slightly high resistivity but nearly the same optical transmittance, compared to those on quartz, under the identical deposition parameters. These results indicate that good electrical and optical properties can be achieved for the VZO films on PC substrate. - Highlights: • V-doped ZnO (VZO) was deposited on polymer substrate. • Effects of V concentration, RF power and growth temperature were investigated. • Resistivity decreased gradually with increasing V concentration. • Low RF power was suitable to obtain low resistivity and high transmittance. • High growth temperature improved both transparency and conductivity.

Structure and photoluminescence properties of Ag-coated ZnO nano-needles

International Nuclear Information System (INIS)

Li Xiaozhu; Wang Yongqian

2011-01-01

Highlights: → ZnO nano-needles were synthesized by thermal oxidation. → Their surfaces were coated with Ag by pulse electro-deposition technique. → The uncoated and coated ZnO nano-needles were characterized. → The results showed that the prepared ZnO nano-needles have been coated with Ag successfully. → The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the Ag-coated ZnO nano-needles can increase the absorption of UV light. - Abstract: A large number of zinc oxide (ZnO) nano-needles were synthesized by thermal oxidation of pure zinc. The surfaces of ZnO nano-needles were coated with a layer of Ag by pulse electro-deposition technique. The uncoated and coated ZnO nano-needles were characterized by using the X-ray diffraction and the scanning electron microscope (SEM). The results showed that the uncoated samples were close-packed hexagonal structure, which showed needle-like morphology. Their average diameter is about 40 nm, lengths up to 5 μm. At the same time we observed that the prepared ZnO nano-needles have been coated with Ag successfully. The photoluminescence spectrums of ZnO nano-needles with Ag-coated and uncoated were analyzed, finding that the uncoated ZnO nano-needles have two fluorescence peaks at 388 nm and 470.8 nm, respectively, the relative intensity of 143.4 and 93.61; and the Ag-coated ZnO nano-needles showed a pair of strong peaks at 387.4 nm and 405.2 nm, the relative intensity of 1366 and 1305, respectively, indicating that the Ag-coated ZnO nano-needles can increase the absorption of UV light.

Growth and photoluminescence of vertically aligned ZnO nanowires/nanowalls

Energy Technology Data Exchange (ETDEWEB)

Fang Fang; Zhao Dongxu; Li Binghui; Zhang Zhenzhong; Zhang Jiying; Shen Dezhen, E-mail: dxzhao2000@yahoo.com.c [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 16 East Nan-Hu Road, Open Economic Zone Changchun 130033 (China)

2009-07-07

By controlling the incoming gas flow, vertically aligned ZnO nanowires and nanowalls have been successfully synthesized on a Si (1 0 0) substrate by the simple physical vapour deposition method. The growth process of the ZnO nanowalls was observed by adjusting the growth time. The probable growth mechanisms of the ZnO nanowires and nanowalls were discussed in detail. In contrast to the photoluminescence results of nanowires, an enhancement of the LO phonon signal was observed in ZnO nanowalls, which was attributed to an additional channel of electron-phonon coupling induced by the residual strains in the ZnO nanowalls during the coalescence growth process.

Photoluminescence study of aligned ZnO nanorods grown using chemical bath deposition

Energy Technology Data Exchange (ETDEWEB)

Urgessa, Z.N. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Oluwafemi, O.S. [Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag XI, 5117 (South Africa); Dangbegnon, J.K. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Botha, J.R., E-mail: Reinhardt.Botha@nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

2012-05-15

The photoluminescence study of self-assembled ZnO nanorods grown on a pre-treated Si substrate by a simple chemical bath deposition method at a temperature of 80 Degree-Sign C is hereby reported. By annealing in O{sub 2} environment the UV emission is enhanced with diminishing deep level emission suggesting that most of the deep level emission is due to oxygen vacancies. The photoluminescence was investigated from 10 K to room temperature. The low temperature photoluminescence spectrum is dominated by donor-bound exciton. The activation energy and binding energy of shallow donors giving rise to bound exciton emission were calculated to be around 13.2 meV, 46 meV, respectively. Depending on these energy values and nature of growth environment, hydrogen is suggested to be the possible contaminating element acting as a donor.

Comparative study of ZnO nanorods and thin films for chemical and biosensing applications and the development of ZnO nanorods based potentiometric strontium ion sensor

Science.gov (United States)

Khun, K.; Ibupoto, Z. H.; Chey, C. O.; Lu, Jun.; Nur, O.; Willander, M.

2013-03-01

In this study, the comparative study of ZnO nanorods and ZnO thin films were performed regarding the chemical and biosensing properties and also ZnO nanorods based strontium ion sensor is proposed. ZnO nanorods were grown on gold coated glass substrates by the hydrothermal growth method and the ZnO thin films were deposited by electro deposition technique. ZnO nanorods and thin films were characterised by field emission electron microscopy [FESEM] and X-ray diffraction [XRD] techniques and this study has shown that the grown nanostructures are highly dense, uniform and exhibited good crystal quality. Moreover, transmission electron microscopy [TEM] was used to investigate the quality of ZnO thin film and we observed that ZnO thin film was comprised of nano clusters. ZnO nanorods and thin films were functionalised with selective strontium ionophore salicylaldehyde thiosemicarbazone [ST] membrane, galactose oxidase, and lactate oxidase for the detection of strontium ion, galactose and L-lactic acid, respectively. The electrochemical response of both ZnO nanorods and thin films sensor devices was measured by using the potentiometric method. The strontium ion sensor has exhibited good characteristics with a sensitivity of 28.65 ± 0.52 mV/decade, for a wide range of concentrations from 1.00 × 10-6 to 5.00 × 10-2 M, selectivity, reproducibility, stability and fast response time of 10.00 s. The proposed strontium ion sensor was used as indicator electrode in the potentiometric titration of strontium ion versus ethylenediamine tetra acetic acid [EDTA]. This comparative study has shown that ZnO nanorods possessed better performance with high sensitivity and low limit of detection due to high surface area to volume ratio as compared to the flat surface of ZnO thin films.

Structural and photoluminescence characterization of vertically aligned multiwalled carbon nanotubes coated with ZnO by magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Ouldhamadouche, N. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere BP 32229 44322 Nantes cedex 3 (France); Laboratoire de Physique des Materiaux, Universite des Sciences et de la Technologie Houari Boumediene, BP 32 El Alla. 16111, Bab Ezzouaur (Algeria); Achour, A., E-mail: a_aminph@yahoo.fr [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere BP 32229 44322 Nantes cedex 3 (France); Musa, I.; Ait Aissa, K.; Massuyeau, F.; Jouan, P.Y. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere BP 32229 44322 Nantes cedex 3 (France); Kechouane, M. [Laboratoire de Physique des Materiaux, Universite des Sciences et de la Technologie Houari Boumediene, BP 32 El Alla. 16111, Bab Ezzouaur (Algeria); Le Brizoual, L.; Faulques, E.; Barreau, N.; Djouadi, M.A. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere BP 32229 44322 Nantes cedex 3 (France)

2012-05-01

Zinc oxide (ZnO) nanostructures are very attractive in various optoelectronic applications such as light emitting devices. A fabrication process of these ZnO nanostructures which gives a good crystalline quality and being compatible with that of micro-fabrication has significant importance for practical application. In this work ZnO films with different thicknesses were deposited by RF-sputtering on vertically aligned multiwalled carbon nanotube (MWCNTs) template in order to obtain ZnO nanorods. The obtained hybrid structures (ZnO/MWCNTs) were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and time resolved photoluminescence spectroscopy (PL). Results show that the ZnO/MWCNTs have a nanorod structure like morphology with a good crystalline quality of the deposited ZnO on the MWCNTs. PL measurements reveal an enhancement of the band edge signal of ZnO/MWCNTs which is three times of magnitude higher compared to the ZnO film deposited on silicon. Moreover, the intensity enhancement varies as function of the ZnO thickness. Such hybrid structures are promising for optoelectronic application, such as blue-violet sources.

Photoluminescence measurements of ZnO heterostructures

International Nuclear Information System (INIS)

Adachi, Yutaka; Sakaguchi, Isao; Ohashi, Naoki; Haneda, Hajime; Ryoken, Haruki; Takenaka, Tadashi

2003-01-01

ZnO thin films were grown on TbAlO 3 single crystal substrates by pulsed laser deposition. In photoluminescence (PL) measurements, strong emissions from TbAlO 3 were observed with the emission from ZnO when the film thickness was less than 100 nm. The relationship between the ZnO film thickness and the emission intensity from TbAlO 3 was investigated in order to determine the penetration depth of excitation light. Information on the heterostructures ranging from the surface to a depth of 300 nm was obtained by PL measurements in this study, and the absorption coefficient for a wavelength of 325 nm was estimated to be 1.31x10 5 cm -1 . (author)

Full coverage of perovskite layer onto ZnO nanorods via a modified sequential two-step deposition method for efficiency enhancement in perovskite solar cells

Science.gov (United States)

Ruankham, Pipat; Wongratanaphisan, Duangmanee; Gardchareon, Atcharawon; Phadungdhitidhada, Surachet; Choopun, Supab; Sagawa, Takashi

2017-07-01

Full coverage of perovskite layer onto ZnO nanorod substrates with less pinholes is crucial for achieving high-efficiency perovskite solar cells. In this work, a two-step sequential deposition method is modified to achieve an appropriate property of perovskite (MAPbI3) film. Surface treatment of perovskite layer and its precursor have been systematically performed and their morphologies have been investigated. By pre-wetting of lead iodide (PbI2) and letting it dry before reacting with methylammonium iodide (MAI) provide better coverage of perovskite film onto ZnO nanorod substrate than one without any treatment. An additional MAI deposition followed with toluene drop-casting technique on the perovskite film is also found to increase the coverage and enhance the transformation of PbI2 to MAPbI3. These lead to longer charge carrier lifetime, resulting in an enhanced power conversion efficiency (PCE) from 1.21% to 3.05%. The modified method could been applied to a complex ZnO nanorods/TiO2 nanoparticles substrate. The enhancement in PCE to 3.41% is observed. These imply that our introduced method provides a simple way to obtain the full coverage and better transformation to MAPbI3 phase for enhancement in performances of perovskite solar cells.

Preparation, structural and luminescent properties of nanocrystalline ZnO films doped Ag by close space sublimation method

Science.gov (United States)

Khomchenko, Viktoriya; Mazin, Mikhail; Sopinskyy, Mykola; Lytvyn, Oksana; Dan'ko, Viktor; Piryatinskii, Yurii; Demydiuk, Pavlo

2018-05-01

The simple way for silver doping of ZnO films is presented. The ZnO films were prepared by reactive rf-magnetron sputtering on silicon and sapphire substrates. Ag doping is carried out by sublimation of the Ag source located at close space at atmospheric pressure in air. Then the ZnO and ZnO-Ag films were annealed in wet media. The microstructure and optical properties of the films were compared and studied by atomic force microscopy (AFM), X-ray diffraction (XRD), photoluminescence (PL) and cathodoluminescence (CL). XRD results indicated that all the ZnO films have a polycrystalline hexagonal structure and a preferred orientation with the c-axis perpendicular to the substrate. The annealing and Ag doping promote increasing grain's sizes and modification of grain size distribution. The effect of substrate temperature, substrate type, Ag doping and post-growth annealing of the films was studied by PL spectroscopy. The effect of Ag doping was obvious and identical for all the films, namely the wide visible bands of PL spectra are suppressed by Ag doping. The intensity of ultraviolet band increased 15 times as compared to their reference films on sapphire substrate. The ultraviolet/visible emission ratio was 20. The full width at half maximum (FWHM) for a 380 nm band was 14 nm, which is comparable with that of epitaxial ZnO. The data implies the high quality of ZnO-Ag films. Possible mechanisms to enhance UV emission are discussed.

Ultrasound assisted synthesis of nanocrystalline zinc oxide: Experiments and modelling

Energy Technology Data Exchange (ETDEWEB)

Hosni, Mongia [Laboratoire des Sciences des Procédés et des Matériaux, LSPM-CNRS, Université Paris 13, 99 av. J.B. Clément, 93430 Villetaneuse (France); Farhat, Samir, E-mail: farhat@lspm.cnrs.fr [Laboratoire des Sciences des Procédés et des Matériaux, LSPM-CNRS, Université Paris 13, 99 av. J.B. Clément, 93430 Villetaneuse (France); Schoenstein, Frederic; Karmous, Farah; Jouini, Noureddine [Laboratoire des Sciences des Procédés et des Matériaux, LSPM-CNRS, Université Paris 13, 99 av. J.B. Clément, 93430 Villetaneuse (France); Viana, Bruno [LCMCP Chimie-Paristech, UPMC, Collège de France, 11 Rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Mgaidi, Arbi [Laboratoire de chimie minérale industrielle université Tunis el Manar (Tunisia)

2014-12-05

Highlights: • ZnO nanospheres and nanowires were grown using ultrasound and thermal activation techniques. • The growth uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). • A thermochemical model was developed based on thermodynamic equilibrium calculations. • We estimate species distribution in the bubble in temperature range from 5000 K to ambient. • We propose a new mechanism for ZnO growth assisted by ultrasound irradiation. - Abstract: A fast and green approach is proposed for the preparation of nanocrystalline zinc oxide (ZnO) via ultrasonic (US) irradiation in polyol medium. The process uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). The protocol is compared to thermal activation under the same chemical environment. The activation method is found to be playing a critical role in the selective synthesis of morphologically distinct nanostructures. As compared to thermally activated conventional polyol process, (US) permits to considerably reduce reaction time as well as size of particles. In addition, the shape of these nanoparticles was changed from long nanowires to small nanospheres, indicating different reaction mechanisms. To explain this difference, a thermochemical model was developed based on thermodynamic equilibrium calculations. The model estimate species distribution in the bubble in temperature range from 5000 K to ambient simulating quenching process during bubble formation and collapse. Our results indicate the presence of high density of zinc atoms that could be responsible of a high density of nucleation as compared to thermal activation.

Ultrasound assisted synthesis of nanocrystalline zinc oxide: Experiments and modelling

International Nuclear Information System (INIS)

Hosni, Mongia; Farhat, Samir; Schoenstein, Frederic; Karmous, Farah; Jouini, Noureddine; Viana, Bruno; Mgaidi, Arbi

2014-01-01

Highlights: • ZnO nanospheres and nanowires were grown using ultrasound and thermal activation techniques. • The growth uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). • A thermochemical model was developed based on thermodynamic equilibrium calculations. • We estimate species distribution in the bubble in temperature range from 5000 K to ambient. • We propose a new mechanism for ZnO growth assisted by ultrasound irradiation. - Abstract: A fast and green approach is proposed for the preparation of nanocrystalline zinc oxide (ZnO) via ultrasonic (US) irradiation in polyol medium. The process uses forced hydrolysis of zinc acetate in diethylene glycol (DEG). The protocol is compared to thermal activation under the same chemical environment. The activation method is found to be playing a critical role in the selective synthesis of morphologically distinct nanostructures. As compared to thermally activated conventional polyol process, (US) permits to considerably reduce reaction time as well as size of particles. In addition, the shape of these nanoparticles was changed from long nanowires to small nanospheres, indicating different reaction mechanisms. To explain this difference, a thermochemical model was developed based on thermodynamic equilibrium calculations. The model estimate species distribution in the bubble in temperature range from 5000 K to ambient simulating quenching process during bubble formation and collapse. Our results indicate the presence of high density of zinc atoms that could be responsible of a high density of nucleation as compared to thermal activation

All-inorganic white light emitting devices based on ZnO nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Nannen, Ekaterina

2012-09-21

Semiconductor nanaocrystals (NCs) are very promising candidates for lightweight large-area rollable displays and light emitting devices (LEDs). They are expected to combine the efficiency, robustness and color tunability of conventional semiconductor LEDs with the flexible fabrication techniques known from OLED technology, since the NCs are compatible with solution processing and therefore can be deposited on virtually any substrates including glass and plastic. Today, NC-LEDs consist of chemically synthesized QDs embedded in organic charge injection and transport layers. The organic layers limit the robustness of the NC-LEDs and result in significant constrictions within the device fabrication procedure, such as organic evaporation steps, inert (i.e. humidity and oxygen free) atmosphere and obligatory encapsulation. These limitations during the production process as well as complex chemical synthesis route of the implemented NCs and organic components lead to high fabrication costs and low turnover. So far, only prototype devices have been introduced by several research groups and industrial companies. Still, the main concern retarding NC-LEDs from market launch is the high content of toxic heavy metals like Cd in the active nanocrystalline light emitting material. Within this work, possible environmentally safe and ambient-air-compatible alternatives to conventional QDs and organics were explored, with the main focus on design and fabrication of completely inorganic white NC-LEDs with commercial ZnO nanoparticles as an active light emitting material. While the electrical transport properties through the NC-network of the commercially available VP AdNano {sup registered} ZnO2O particles were already to some extent explored, their optical properties and therefore suitability as an active light emitter in NC-LEDs were not studied so far. (orig.)

Photoluminescence and lasing properties of ZnO nanorods

International Nuclear Information System (INIS)

Lee, Geon Joon; Lee, Young Pak; Min, Sun Ki; Han, Sung Hwan; Lim, Hwan Hong; Cha, Myoung Sik; Kim, Sung Soo; Cheong, Hyeon Sik

2010-01-01

In this study, we investigated the structures, photoluminescence (PL), and lasing characteristics of the ZnO nanorods prepared by using chemical bath deposition. The continuous-wave HeCd laser excited PL spectra of the ZnO nanorods exhibited two emission bands, one in the UV region and the other in the visible region. The UV emission band has its peak at 3.25 eV with a bandwidth of 160 meV. However, the PL spectra under 355-nm, 35-ps pulse excitation exhibited a spectrally-narrowed UV emission band with a peak at 3.20 eV and a spectral width of 35 meV. The lasing phenomena were ascribed to the amplified spontaneous emission (ASE) caused by coupling of the microcavity effect of ZnO nanorods and the high-intensity excitation. Above the lasing threshold, the ASE peak intensity exhibited a superlinear dependence on the excitation intensity. For an excitation pulse energy of 3 mJ, the ASE peak intensity was increased by enlarging the length of the ZnO nanorods from 1 μm to 4 μm. In addition, the PL spectrum under 800-nm femtosecond pulse excitation exhibited second harmonic generation, as well as the multiphoton absorption-induced UV emission band. In this research, ZnO nanorods were grown on seed layers by using chemical bath deposition in an aqueous solution of Zn(NO 3 ) 2 and hexamethyltetramine. The seed layers were prepared on conducting glass substrates by dip coating in an aqueous colloidal dispersion containing 50% 70-nm ZnO nanoparticles. Scanning electron microscopy clearly revealed that ZnO nanorods were successfully grown on the seed layers.

Hybrid inorganic–organic superlattice structures with atomic layer deposition/molecular layer deposition

Energy Technology Data Exchange (ETDEWEB)

Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit, E-mail: maarit.karppinen@aalto.fi [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland)

2014-01-15

A combination of the atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques is successfully employed to fabricate thin films incorporating superlattice structures that consist of single layers of organic molecules between thicker layers of ZnO. Diethyl zinc and water are used as precursors for the deposition of ZnO by ALD, while three different organic precursors are investigated for the MLD part: hydroquinone, 4-aminophenol and 4,4′-oxydianiline. The successful superlattice formation with all the organic precursors is verified through x-ray reflectivity studies. The effects of the interspersed organic layers/superlattice structure on the electrical and thermoelectric properties of ZnO are investigated through resistivity and Seebeck coefficient measurements at room temperature. The results suggest an increase in carrier concentration for small concentrations of organic layers, while higher concentrations seem to lead to rather large reductions in carrier concentration.

ZnO - Wide Bandgap Semiconductor and Possibilities of Its Application in Optical Waveguide Structures

Directory of Open Access Journals (Sweden)

Struk Przemysław

2014-08-01

Full Text Available The paper presents the results of investigations concerning the application of zinc oxide - a wideband gap semiconductor in optical planar waveguide structures. ZnO is a promising semiconducting material thanks to its attractive optical properties. The investigations were focused on the determination of the technology of depositions and the annealing of ZnO layers concerning their optical properties. Special attention was paid to the determination of characteristics of the refractive index of ZnO layers and their coefficients of spectral transmission within the UV-VIS-NIR range. Besides that, also the mode characteristics and the attenuation coefficients of light in the obtained waveguide structures have been investigated. In the case of planar waveguides, in which the ZnO layers have not been annealed after their deposition, the values of the attenuation coefficient of light modes amount to a~ 30 dB/cm. The ZnO layers deposited on the heated substrate and annealed by rapid thermal annealing in an N2 and O2 atmosphere, are characterized by much lower values of the attenuation coefficients: a~ 3 dB/cm (TE0 and TM0 modes. The ZnO optical waveguides obtained according to our technology are characterized by the lowest values of the attenuation coefficients a encountered in world literature concerning the problem of optical waveguides based on ZnO. Studies have shown that ZnO layers elaborated by us can be used in integrated optic systems, waveguides, optical modulators and light sources.

The optical properties of ZnO films grown on porous Si templates

International Nuclear Information System (INIS)

Liu, Y L; Liu, Y C; Yang, H; Wang, W B; Ma, J G; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

2003-01-01

ZnO films were electrodeposited on porous silicon templates with different porosities. The photoluminescence (PL) spectra of the samples before and after deposition of ZnO were measured to study the effect of template porosity on the luminescence properties of ZnO/porous Si composites. As-prepared porous Si (PS) templates emit strong red light. The red PL peak of porous Si after deposition of ZnO shows an obvious blueshift, and the trend of blueshift increases with an increase in template porosity. A green emission at about 550 nm was also observed when the porosity of template increases, which is ascribed to the deep-level emission band of ZnO. A model-based band diagram of the ZnO/porous Si composite is suggested to interpret the properties of the composite

Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

KAUST Repository

Roqan, Iman S.

2016-08-29

The magnetic properties of Gd-doped ZnO films and nanostructures are important to the development of next-generation spintronic devices. Here, we elucidate the significant role played by Gd-oxygen-deficiency defects in mediating/inducing ferromagnetic coupling in in situ Gd-doped ZnO thin films deposited at low oxygen pressure by pulsed laser deposition (PLD). Samples deposited at higher oxygen pressures exhibited diamagnetic responses. Vacuum annealing was used on these diamagnetic samples (grown at a relatively high oxygen pressures) to create oxygen- deficiency defects with the aim of demonstrating reproducibility of room-temperature ferromagnetism (RTFM). Samples annealed at oxygen environment exhibited super‐ paramagnetism and blocking-temperature effects. The samples possessed secondary phases; Gd segregation led to superparamagnetism. Theoretical studies showed a shift of the 4f level of Gd to the conduction band minimum (CBM) in Gd-doped ZnO nanowires, which led to an overlap with the Fermi level, resulting in strong exchange coupling and consequently RTFM.

Optimization of Electrochemically Deposited Highly Doped ZnO Bilayers on Ga-Rich Chalcopyrite Selenide for Cost-Effective Photovoltaic Device Technology

Directory of Open Access Journals (Sweden)

Dimitra N. Papadimitriou

2016-11-01

Full Text Available High quality polycrystalline bilayers of aluminium doped ZnO (Al:ZnO were successively electrodeposited in the form of columnar structures preferentially oriented along the ( 10 1 ¯ 1 crystallographic direction from aqueous solution of zinc nitrate (Zn(NO32 at negative electrochemical potential of EC = (−0.8–(−1.2 V and moderate temperature of 80 °C on gallium rich (30% Ga chalcopyrite selenide Cu(In,GaSe2 (CIGS with chemically deposited ZnSe buffer (ZnSe/Cu(In,GaSe2/Mo/glass. The aluminium doped ZnO layer properties have initially been probed by deposition of Al:ZnO/i-ZnO bilayers directly on Mo/glass substrates. The band-gap energy of the Al:ZnO/i-ZnO reference layers was found to vary from 3.2 to 3.7 eV by varying the AlCl3 solute dopant concentration from 1 to 20 mM. The electrical resistivity of indium-pellet contacted highly doped Al:ZnO sheet of In/Al:ZnO/i-ZnO/Mo/glass reference samples was of the order ρ ~10−5 Ω·cm; the respective carrier concentration of the order 1022 cm−3 is commensurate with that of sputtered Al:ZnO layers. For crystal quality optimization of the bilayers by maintenance of the volatile selenium content of the chalcopyrite, they were subjected to 2-step annealing under successive temperature raise and N2 flux regulation. The hydrostatic compressive strain due to Al3+ incorporation in the ZnO lattice of bilayers processed successively with 5 and 12 mM AlCl3 dopant was εh = −0.046 and the respective stress σh = −20 GPa. The surface reflectivity of maximum 5% over the scanned region of 180–900 nm and the (optical band gap of Eg = 3.67 eV were indicative of the high optical quality of the electrochemically deposited (ECD Al:ZnO bilayers.

Synthesis of ordered large-scale ZnO nanopore arrays

International Nuclear Information System (INIS)

Ding, G.Q.; Shen, W.Z.; Zheng, M.J.; Fan, D.H.

2006-01-01

An effective approach is demonstrated for growing ordered large-scale ZnO nanopore arrays through radio-frequency magnetron sputtering deposition on porous alumina membranes (PAMs). The realization of highly ordered hexagonal ZnO nanopore arrays benefits from the unique properties of ZnO (hexagonal structure, polar surfaces, and preferable growth directions) and PAMs (controllable hexagonal nanopores and localized negative charges). Further evidence has been shown through the effects of nanorod size and thermal treatment of PAMs on the yielded morphology of ZnO nanopore arrays. This approach opens the possibility of creating regular semiconducting nanopore arrays for the application of filters, sensors, and templates

Nano-structural properties of ZnO films for Si based heterojunction solar cells

Energy Technology Data Exchange (ETDEWEB)

Breivik, T.H. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway)], E-mail: t.h.breivik@fys.uio.no; Diplas, S. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway); University of Oslo, Center for Material Science and Nanotechnology, P.O. Box 1126, Blindern, NO-0318 Oslo (Norway); Ulyashin, A.G. [Section for Renewable Energy, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway); Gunnaes, A.E. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway); Olaisen, B.R.; Wright, D.N.; Holt, A. [Section for Renewable Energy, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller (Norway); Olsen, A. [University of Oslo, Department of Physics, P.O. Box 1048, Blindern, NO-0316, Oslo (Norway)

2007-10-15

Properties and structure of ZnO and ZnO:Al films deposited on c-Si, a-Si:H/Si and glass substrates are studied by various methods. The transmittance of the ZnO:Al was found to be higher when compared to ZnO, and the refractive index lower. X-ray photoelectron spectroscopy (XPS) shows that the screening efficiency in the presence of core holes is enhanced in the Al doped ZnO. The roughness of the ZnO:Al surfaces is strongly substrate dependent. With transmission electron microscopy (TEM) a 2-3 nm thick amorphous interfacial layer was observed independently of substrate and doping. Deposition of ZnO on a-Si:H substrate results in crystallization of the a-Si:H layer independently of Al doping.

Nano-structural properties of ZnO films for Si based heterojunction solar cells

International Nuclear Information System (INIS)

Breivik, T.H.; Diplas, S.; Ulyashin, A.G.; Gunnaes, A.E.; Olaisen, B.R.; Wright, D.N.; Holt, A.; Olsen, A.

2007-01-01

Properties and structure of ZnO and ZnO:Al films deposited on c-Si, a-Si:H/Si and glass substrates are studied by various methods. The transmittance of the ZnO:Al was found to be higher when compared to ZnO, and the refractive index lower. X-ray photoelectron spectroscopy (XPS) shows that the screening efficiency in the presence of core holes is enhanced in the Al doped ZnO. The roughness of the ZnO:Al surfaces is strongly substrate dependent. With transmission electron microscopy (TEM) a 2-3 nm thick amorphous interfacial layer was observed independently of substrate and doping. Deposition of ZnO on a-Si:H substrate results in crystallization of the a-Si:H layer independently of Al doping

Epitaxial GaN around ZnO nanopillars

Energy Technology Data Exchange (ETDEWEB)

Fikry, Mohamed; Scholz, Ferdinand [Institut fuer Optoelektronik, Universitaet Ulm, Albert-Einstein-Allee 45, 89081 Ulm (Germany); Madel, Manfred; Tischer, Ingo; Thonke, Klaus [Institut fuer Quantenmaterie, Universitaet Ulm, Albert-Einstein-Allee 45, 89081 Ulm (Germany)

2011-07-01

We report on an investigation of the epitaxial quality of GaN layers overgrown coaxially around ZnO nanopillars. In a first step, regularly arranged ZnO nanopillars were grown using pre-patterning by e-beam lithography or self-organized hexagonal polystyrene sphere masks. Alternatively, ZnO pillars were also successfully grown on top of GaN pyramids. In a second step, GaN layers were grown around the ZnO pillars by Metal Organic Vapor Phase Epitaxy. At growth temperatures above 800 C, the ZnO pillars are dissolved by the hydrogen carrier gas leaving hollow GaN nanotubes. Characterization involved photoluminescence (PL), scanning electron microscopy and cathodoluminescence. The fair quality of the deposited GaN layers is confirmed by a sharp low temperature PL peak at 3.48 eV attributed to the donor bound exciton emission. Further peaks at 3.42 eV and 3.29 eV show the possible existence of basal plane and prismatic stacking faults.

Nanocrystalline ceramic materials

Science.gov (United States)

Siegel, Richard W.; Nieman, G. William; Weertman, Julia R.

1994-01-01

A method for preparing a treated nanocrystalline metallic material. The method of preparation includes providing a starting nanocrystalline metallic material with a grain size less than about 35 nm, compacting the starting nanocrystalline metallic material in an inert atmosphere and annealing the compacted metallic material at a temperature less than about one-half the melting point of the metallic material.

Preparation of Aligned ZnO Nanorod Arrays on Sn-Doped ZnO Thin Films by Sonicated Sol-Gel Immersion Fabricated for Dye-Sensitized Solar Cell

Directory of Open Access Journals (Sweden)

I. Saurdi

2014-01-01

Full Text Available Aligned ZnO Nanorod arrays are deposited on the Sn-doped ZnO thin film via sonicated sol-gel immersion method. The structural, optical, and electrical properties of the Sn-doped ZnO thin films were investigated. Results show that the Sn-doped ZnO thin films with small grain size (~20 nm, high average transmittance (96% in visible region, and good resistivity 7.7 × 102 Ω·cm are obtained for 2 at.% Sn doping concentration. The aligned ZnO nanorod arrays with large surface area were also obtained for 2 at.% Sn-doped ZnO thin film. They were grown on sol-gel derived Sn-doped ZnO thin film, which acts as a seed layer, via sonicated sol-gel immersion method. The grown aligned ZnO nanorod arrays show high transmittance at visible region. The fabricated dye-sensitised solar cell based on the 2.0 at.% Sn-doped ZnO thin film with aligned ZnO nanorod arrays exhibits improved current density, open-circuit voltage, fill factor, and conversion efficiency compared with the undoped ZnO and 1 at.% Sn-doped ZnO thin films.

Thermoelectric nanocrystalline YbCoSb laser prepared layers

Czech Academy of Sciences Publication Activity Database

Jelínek, Miroslav; Zeipl, Radek; Kocourek, Tomáš; Remsa, Jan; Navrátil, Jiří

2016-01-01

Roč. 122, č. 3 (2016), s. 1-5, č. článku 155. ISSN 0947-8396 R&D Projects: GA ČR(CZ) GA13-33056S Institutional support: RVO:68378271 ; RVO:61389013 Keywords : nanocrystalline YbCoSb * thermoelectric layers * pulsed laser deposition Subject RIV: BM - Solid Matter Physics ; Magnetism; CA - Inorganic Chemistry (UMCH-V) Impact factor: 1.455, year: 2016

The chemical and catalytic properties of nanocrystalline metal oxides prepared through modified sol-gel synthesis

Science.gov (United States)

Carnes, Corrie Leigh

The goal of this research was to synthesize, characterize and study the chemical properties of nanocrystalline metal oxides. Nanocrystalline (NC) ZnO, CuO, NiO, Al2O3, and the binary Al2O 3/MgO and ZnO/CuO were prepared through modified sol gel methods. These NC metal oxides were studied in comparison to the commercial (CM) metal oxides. The samples were characterized by XRD, TGA, FTIR, BET, and TEM. The NC samples were all accompanied by a significant increase in surface area and decrease in crystallite size. Several chemical reactions were studied to compare the NC samples to the CM samples. One of the reactions involved a high temperature reaction between carbon tetrachloride and the oxide to form carbon dioxide and the corresponding metal chloride. A similar high temperature reaction was conducted between the metal oxide and hydrogen sulfide to form water and the corresponding metal sulfide. A room temperature gas phase adsorption was studied where SO2 was adsorbed onto the oxide. A liquid phase adsorption conducted at room temperature was the destructive adsorption of paraoxon (a toxic insecticide). In all reactions the NC samples exhibited greater activity, destroying or adsorbing a larger amount of the toxins compared to the CM samples. To better study surface area effects catalytic reactions were also studied. The catalysis of methanol was studied over the nanocrystalline ZnO, CuO, NiO, and ZnO/CuO samples in comparison to their commercial counterparts. In most cases the NC samples proved to be more active catalysts, having higher percent conversions and turnover numbers. A second catalytic reaction was also studied, this reaction was investigated to look at the support effects. The catalysis of cyclopropane to propane was studied over Pt and Co catalysts. These catalysts were supported onto NC and CM alumina by impregnation. By observing differences in the catalytic behavior, support effects have become apparent.

Characterization of Zinc Oxide (ZnO) piezoelectric properties for Surface Acoustic Wave (SAW) device

Science.gov (United States)

Rosydi Zakaria, Mohd; Johari, Shazlina; Hafiz Ismail, Mohd; Hashim, Uda

2017-11-01

In fabricating Surface Acoustic Wave (SAW) biosensors device, the substrate is one of important factors that affected to performance device. there are many types of piezoelectric substrate in the markets and the cheapest is zinc Oxide substrate. Zinc Oxide (ZnO) with its unique properties can be used as piezoelectric substrate along with SAW devices for detection of DNA in this research. In this project, ZnO thin film is deposited onto silicon oxide substrate using electron beam evaporation (E-beam) and Sol-Gel technique. Different material structure is used to compare the roughness and best piezoelectric substrate of ZnO thin film. Two different structures of ZnO target which are pellet and granular are used for e-beam deposition and one sol-gel liquid were synthesize and compared. Parameter for thickness of ZnO e-beam deposition is fixed to a 0.1kÅ for both materials structure and sol-gel was coat using spin coat technique. After the process is done, samples are annealed at temperature of 500°C for 2 hours. The structural properties of effect of post annealing using different material structure of ZnO are studied using Atomic Force Microscopic (AFM) for surface morphology and X-ray Diffraction (XRD) for phase structure.

The surface defect-related electroluminescence from the ZnO microwire

Energy Technology Data Exchange (ETDEWEB)

Ding Meng; Zhao Dongxu; Yao Bin; Li Binghui; Zhang Zhenzhong; Shan Chongxin; Shen Dezhen, E-mail: dxzhao2000@yahoo.com.cn [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130021 (China)

2011-02-23

Surface defect-related electroluminescence (EL) was realized from a single ZnO microwire-based metal-semiconductor-metal structure on a glass substrate. ZnO microwires were successfully fabricated using a simple chemical vapour deposition approach. Schottky contacts were detected between Au electrodes and the ZnO microwire. The EL spectrum showed a broad emission band covering the visible range from 400 to 700 nm. The possible EL emission mechanism is discussed in detail in this paper.

Growth and Properties of Cl- Incorporated ZnO Nanofilms Grown by Ultrasonic Spray-Assisted Chemical Vapor Deposition.

Science.gov (United States)

Chen, Tingfang; Wang, Aiji; Kong, Lingrui; Li, Yongliang; Wang, Yinshu

2016-04-01

Pure and Cl- incorporated ZnO nanofilms were grown by the ultrasonic spray-assisted chemical vapor deposition (CVD) method. The properties of the nanofilms were investigated. The effects of growth temperature and Cl- concentration on the crystal structure, morphology, and optical properties of the nanofilms were studied. Temperature plays an important role in the growth mode and morphology of the pure nanofilms. Preferential growth along the c-axis occurs only at modulating temperature. Lower temperature suppresses the preferential growth, and higher temperature suppresses the growth of the nanofilms. The morphologies of the nanofilms change from lamellar and spherical structures into hexagonal platelets, then into separated nanoparticles with an increase in the temperature. Incorporating Cl- results in the lattice contracting gradually along with c-axis. Grains composing the nanofilms refine, and the optical gap broadens with increasing of Cl- concentration in growth precursor. Incorporating Cl- could reduce oxygen vacancies and passivate the non-irradiated centers, thus enhancing the UV emission and suppressing the visible emission of ZnO nanofilms.

Microwave plasma chemical synthesis of nanocrystalline carbon film structures and study their properties

Science.gov (United States)

Bushuev, N.; Yafarov, R.; Timoshenkov, V.; Orlov, S.; Starykh, D.

2015-08-01

The self-organization effect of diamond nanocrystals in polymer-graphite and carbon films is detected. The carbon materials deposition was carried from ethanol vapors out at low pressure using a highly non-equilibrium microwave plasma. Deposition processes of carbon film structures (diamond, graphite, graphene) is defined. Deposition processes of nanocrystalline structures containing diamond and graphite phases in different volume ratios is identified. The solid film was obtained under different conditions of microwave plasma chemical synthesis. We investigated the electrical properties of the nanocrystalline carbon films and identified it's from various factors. Influence of diamond-graphite film deposition mode in non-equilibrium microwave plasma at low pressure on emission characteristics was established. This effect is justified using the cluster model of the structure of amorphous carbon. It was shown that the reduction of bound hydrogen in carbon structures leads to a decrease in the threshold electric field of emission from 20-30 V/m to 5 V/m. Reducing the operating voltage field emission can improve mechanical stability of the synthesized film diamond-graphite emitters. Current density emission at least 20 A/cm2 was obtained. Nanocrystalline carbon film materials can be used to create a variety of functional elements in micro- and nanoelectronics and photonics such as cold electron source for emission in vacuum devices, photonic devices, cathodoluminescent flat display, highly efficient white light sources. The obtained graphene carbon net structure (with a net size about 6 μm) may be used for the manufacture of large-area transparent electrode for solar cells and cathodoluminescent light sources

Enhanced superconductivity and superconductor to insulator transition in nano-crystalline molybdenum thin films

Energy Technology Data Exchange (ETDEWEB)

Sharma, Shilpam; Amaladass, E.P. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Sharma, Neha [Surface & Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Harimohan, V. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Amirthapandian, S. [Materials Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Mani, Awadhesh, E-mail: mani@igcar.gov.in [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2017-06-01

Disorder driven superconductor to insulator transition via intermediate metallic regime is reported in nano-crystalline thin films of molybdenum. The nano-structured thin films have been deposited at room temperature using DC magnetron sputtering at different argon pressures. The grain size has been tuned using deposition pressure as the sole control parameter. A variation of particle sizes, room temperature resistivity and superconducting transition has been studied as a function of deposition pressure. The nano-crystalline molybdenum thin films are found to have large carrier concentration but very low mobility and electronic mean free path. Hall and conductivity measurements have been used to understand the effect of disorder on the carrier density and mobilities. Ioffe-Regel parameter is shown to correlate with the continuous metal-insulator transition in our samples. - Highlights: • Thin films of molybdenum using DC sputtering have been deposited on glass. • Argon background pressure during sputtering was used to tune the crystallite sizes of films. • Correlation in deposition pressure, disorder and particle sizes has been observed. • Disorder tuned superconductor to insulator transition along with an intermediate metallic phase has been observed. • Enhancement of superconducting transition temperature and a dome shaped T{sub C} vs. deposition pressure phase diagram has been observed.

Influence of variation in the concentration of ammonium hydroxide on the size of ZnO crystal obtained by Microwave Chemical Bath Deposition

International Nuclear Information System (INIS)

Galeazzi, R; Díaz, T; García, G; Rivera, B L; Rosendo, E; López, R; Morales, N; González, C M

2013-01-01

Films of good crystalline quality of ZnO were successfully prepared using the microwave chemical bath deposition method at a temperature of 80 °C. Concentration of the basic precursor was varied systematically in order to obtain different degrees of acidity in the precursor solutions. Increasing the pH causes an increase in yield. This increase is reflected on the thickness of the deposit. The results of atomic force microscopy (AFM) show an increase in particle size with increasing pH in agreement with the results obtained by profilometry.

Investigation of the Optimal Parameters in Hydrothermal Method for the Synthesis of ZnO Nanorods

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Ying-Chung Chen

2014-01-01

Full Text Available We investigated a two-step method to deposit the ZnO-based nanostructure films, including nanorods and nanoflowers. In the first step, sputtering method was used to deposit the ZnO films on SiO2/Si substrates as the seed layer. In the second step, Zn(NO32–6H2O and C6H12N4 were used as precursors and hydrothermal process was used as the method to synthesize the ZnO films. After that, the ZnO films were measured by an X-ray diffraction pattern and a FESEM to analyze their crystallization and morphology. We had found that the ZnO films had three different morphologies synthesized on ZnO/SiO2/Si substrates, including irregular-plate structure films, nanorod films, and beautiful chrysanthemum-like clusters (nanoflower films. We would prove that the face direction of ZnO/SiO2/Si substrates in the hydrothermal bottle and deposition time were two important factors to influence the synthesized results of the ZnO films.

The growth of nanoscale ZnO films by pulsed-spray evaporation chemical vapor deposition and their structural, electric and optical properties

International Nuclear Information System (INIS)

Jiang Yinzhu; Bahlawane, Naoufal

2010-01-01

Great interest in nanoscale thin films (sub-100 nm) has been stimulated by the developing demands of functional devices. In this paper, nanoscale zinc oxide (ZnO) thin films were deposited on glass substrates at 300 o C by pulsed-spray evaporation chemical vapor deposition. Scanning electron micrographs indicate uniform surface morphologies composed of nanometer-sized spherical particles. The growth kinetics and growth mode are studied and the relationship between the film thickness and the electric properties with respect to the growth mode is interpreted. X-ray diffraction shows that all ZnO films grown by this process were crystallized in a hexagonal structure and highly oriented with their c-axes perpendicular to the plane of the substrate. Optical measurements show transparencies above 85% in the visible spectral range for all films. The absorbance in the UV spectral range respects well the Beer-Lambert law, enabling an accurate optical thickness measurement, and the absorption coefficient was measured for a selected wavelength. The measured band gap energies exhibit an almost constant value of 3.41 eV for all films with different thicknesses, which attributed to the thickness-independent crystallite size.