共查询到20条相似文献,搜索用时 31 毫秒
1.
K. Bindu C. Sudha Kartha K. P. Vijayakumar T. Abe Y. Kashiwaba 《Solar Energy Materials & Solar Cells》2003,79(1):3107
Copper indium selenide thin films were prepared through a novel and an eco-friendly selenisation process. In this method, selenium film required for selenisation was prepared using chemical bath deposition technique, at room temperature. Thus, totally avoided usage of highly toxic H2Se or selenium vapour. Here, the process involved annealing the Stacked layer, Se/In/Cu in which Cu and In were deposited using vacuum evaporation technique. Investigations on the solid-state reaction between the layers were done by analysing structural and optical properties of films formed at different annealing temperatures. Optimum annealing condition for the formation of copper indium selenide thin film was found to be 673 K for 1 h in high vacuum. Compositional dependence of the growth process was also studied using various Cu/In ratios. Optical band gap was decreased with increase in Cu/In ratio. Carrier concentration and hence conductivity were found to be increased with increase in Cu/In ratio. The films obtained were p-type and highly Cu-rich films were degenerate. 相似文献
2.
M. Saleem M.F. Al-Kuhaili S.M.A. Durrani I.A. Bakhtiari 《International Journal of Hydrogen Energy》2013
We report the surface modification and growth of nanostructures on the surface of titanium oxide thin films during post deposition annealing in molecular hydrogen ambient. Titanium oxide thin films of a thickness of 200 nm were deposited by electron-beam evaporation at a substrate temperature of 300 °C. Films were annealed in 50 and 100 sccm flow rates of hydrogen in the temperature range of 200 °C–600 °C for 4 h. X-ray diffraction analysis showed a polycrystalline structure of the films. Anatase-to-rutile phase transformation took place, and was influenced by the hydrogen flow rate. Atomic force microscopy indicated the growth of 4–6 μm domains enclosed by nanowalls-like boundaries on the surface when the rutile phase was formed. Spectrophotometer measurements indicated that the films were transparent and a red shift in absorption edge was observed due to annealing. The direct band gaps of anatase and rutile were found to be 3.5 eV and 3.2 eV, respectively. 相似文献
3.
Xuege Wang Sheng S. Li C.H. Huang S. Rawal J.M. Howard V. Craciun T.J. Anderson O.D. Crisalle 《Solar Energy Materials & Solar Cells》2005,88(1):1463
Pulsed non-melt laser annealing (NLA) has been used for the first time to modify near-surface defects and related junction properties in Cu(In,Ga)Se2 (CIGS) solar cells. CIGS films deposited on Mo/glass substrates were annealed using a 25 ns pulsed 248 nm laser beam at selected laser energy density in the range 20–60 mJ/cm2 and pulse number in the range 5–20 pulses. XRD peak narrowing and SEM surface feature size increase suggest near-surface structure changes. Dual-beam optical modulation (DBOM) and Hall-effect measurements indicate NLA treatment increases the effective carrier lifetime and mobility along with the sheet resistance. In addition, several annealed CdS/CIGS films processed by NLA were fabricated into solar cells and characterized by photo- and dark-J–V and quantum efficiency (QE) measurements. The results show significant improvement in the overall cell performance when compared to unannealed cells. The results suggest that an optimal NLA energy density and pulse number for a 25 ns pulse width are approximately 30 mJ/cm2 and 5 pulses, respectively. The NLA results reveal that overall cell efficiency of a cell processed from an unannealed film increased from 7.69% to 13.41% and 12.22% after annealing 2 different samples at the best condition prior to device processing. 相似文献
4.
Sina Saremi-Yarahmadi Bala Vaidhyanathan K.G. Upul Wijayantha 《International Journal of Hydrogen Energy》2010
It is demonstrated for the first time that significant enhancement of photoelectrochemical performance could be achieved by using microwave-assisted annealing for the fabrication of α-Fe2O3 thin films. The process can also lead to significant energy savings (>60% when compared with conventional methods). Different types of Fe thin films were oxidized using both microwave and conventional heating techniques. The photoelectrochemical performance of electrodeposited, undoped and Si-doped iron oxide samples showed that microwave-annealing resulted in superior structural and performance enhancements. The photocurrent densities obtained from microwave annealed samples are among the highest values reported for α-Fe2O3 photoelectrodes fabricated at low temperatures and short times; the highest photocurrent density at 0.55 V vs. VAg/AgCl, before the dark current onset, was 450 μA cm−2 for the Si-doped films annealed at 270 °C for 15 min using microwave irradiation (and 180 μA cm−2 at 0.23 V vs. VAg/AgCl) while conventional annealing at the same temperature resulted in samples with negligible (3 μA cm−2) photoactivity. In contrast, a 450 °C/15 min conventional heat treatment only resulted in a film with 25% lower photocurrent density than that of the microwave annealed sample. The improved performance is attributed to the lower processing temperatures and rapidity of the microwave method that help to retain the nanostructure of the thin films whilst restricting the grain growth to a minimum. The lower processing temperature requirements of the microwave process can also open up the possibility of fabricating hematite thin films on conducting, flexible, plastic electronic substrates. 相似文献
5.
A. Elfanaoui E. ElhamriL. Boulkaddat A. IhlalK. Bouabid L. LaanabA. Taleb X. Portier 《International Journal of Hydrogen Energy》2011,36(6):4130-4133
Hydrogen is a renewable and non-polluting fuel. Its production from water using renewable energy is an attractive challenge. In this work we report some results on the preparation of titanium oxide TiO2 thin films for environmental applications such as water photosplitting. TiO2 thin films have been prepared by spin coating technique of sol precursor onto glass substrates. The deposited films were annealed at different temperatures in air. The X-ray diffraction (XRD) experiments show that the two well-known anatase and rutile phases were observed depending both on the conditions of deposition and on the temperature of annealing. The best conditions of crystallization were found to be around 400 °C in air. The influence of the number of deposited layer on the crystalline quality of the films was investigated. The surface morphology of the deposited film was characterized by atomic force microscopy (AFM) and scanning electronic microscopy (SEM). The UV-Vis-NIR spectroscopy shows that the film exhibits a high transmission around 90%. The best layers were obtained when concentrated (HCl) was added to the sol solutions. The direct band gap of the films was found to be around 3.7 eV, and their refractive index was found to vary from 2 to 2.4. 相似文献
6.
S.A. Mayn-Hernndez G. Torres-Delgado R. Castanedo-Prez J. Mrquez Marín M. Gutirrez-Villarreal O. Zelaya-Angel 《Solar Energy Materials & Solar Cells》2007,91(15-16):1454-1457
ZnO+Zn2TiO4 thin films were obtained by the sol–gel method, the precursor solutions were prepared using two Ti/Zn ratios: 0.49 and 0.69. The films were deposited on glass slide substrates and sintered at temperatures in the 200–600 °C range in increments of 50 °C, with the goal of studying the dependence of the photocatalytic activity (PA) on the annealing temperature. The films were characterized by X-ray diffraction and UV–Vis spectroscopy. The PA was evaluated by measuring the UV–Vis absorption spectra of the methylene blue in aqueous solution before and after photobleaching, using the Lambert–Beer's principle. The higher photocatalytic activities were obtained from the films with sintering temperature around 450 °C, for both Ti/Zn ratios studied. 相似文献
7.
Chia-Ching Liao Fu-Rong Chen Ji-Jung Kai 《Solar Energy Materials & Solar Cells》2007,91(13):1258-1266
The effect of thermal annealing on the electrochromic properties of the tungsten oxide (WO3−x) nanowires deposited on a transparent conducting substrate by vapor evaporation was investigated. The X-ray diffraction (XRD) indicated that the structures of the nanowries annealed below 500 °C had no significant change. The X-ray photoelectron spectroscopy (XPS) analysis suggested that the O/W ratio and the amount of W6+ ions in the annealed nanowire films could be increased as increasing annealing temperature. Increased annealing temperature could promote the coloration efficiency and contrast of the nanowire films; however, it could also affect the switching speed of the nanowire films. 相似文献
8.
《International Journal of Hydrogen Energy》2022,47(31):14339-14345
The ZnTe material has an unprecedented role in the fabrication of high efficiency CdTe thin film solar cells and optimization of hydrogen annealing induced physical properties of ZnTe films is next required step. Consequently, in the present work, the impact of Hydrogen annealing temperature on the structural, optical, electrical, topographical, morphological, and compositional properties of ZnTe films is explored. The ZnTe thin films (having 300 nm thickness) are grown via electron-beam evaporation technique on glass and ITO substrates followed by annealing at different temperatures under a Hydrogen atmosphere. The ZnTe films are found to crystallize in cubic phase with (111) predominant peak having crystallite size in the range of 19–28 nm, whereas annealed films demonstrated lower optical transmittance vis-à-vis to pristine films. The PL spectra exhibit two luminescence peaks with a stronger band at ~351 nm and a weaker band at ~450 nm. Ohmic behavior of ZnTe films is assured through I–V characteristics, while the AFM images revealed hill-like surface topographies. The FESEM image of pristine films demonstrated a homogeneous surface comprising spherical grains whereas annealed films have spherical, stone, and blisters like morphologies. The EDS patterns assured the Te element richness as well as successful ZnTe films deposition. The observed findings signify that the Hydrogen annealing at different temperatures notably modified the physical properties of ZnTe films. 相似文献
9.
Jingxia Yang Zhengguo Jin Tongjun Liu Chengjie Li Yong Shi 《Solar Energy Materials & Solar Cells》2008,92(6):621-627
SILAR deposition of CuInSe2 films was performed by using Cu2+–TEAH3 (cupric chloride and triethanolamine) and In3+–CitNa (indium chloride and sodium citrate) chelating solutions with weak basic pH as well as Na2SeSO3 solution at 70 °C. A separate mode and a mixed one of cationic precursor solutions were adopted to investigate effects of the immersion programs on crystallization, composition and morphology of the deposited CuInSe2 films. Chelating chemistry in two solution modes was deducted based on IR measurement. The XRD, XPS and SEM results showed that well-crystallized, smoothly and distinctly particular CuInSe2 films could be obtained after annealing in Ar at 400 °C for 1 h by using the mixed cationic solution mode. 相似文献
10.
J. Dheepa R. Sathyamoorthy S. Velumani A. Subbarayan K. Natarajan P. J. Sebastian 《Solar Energy Materials & Solar Cells》2004,81(3):6553
Semiconducting chalcogenide thin films have been receiving considerable attention in the recent years because of their wide applications in the various fields of science and technology. The studies of the electronic properties of semiconductors have been largely stimulated by attractive micro-electronic device applications. Among the various V–VI compounds, Bismuth Telluride (Bi2Te3) is an established low-temperature thermo electric material and is widely employed in thermoelectric generators and coolers. The present work deals with the structural and the electrical characterization of Bi2Te3 thin films vacuum deposited on well-cleaned glass substrates. A constant rate of deposition was maintained through out the process. To obtain uniform and homogeneous film thickness through out on all the substrates a rotary drive was employed. Quartz crystal thickness monitor was used to measure the thickness of the samples. From the X-ray diffractogram the Bi2Te3 films are found to be amorphous at lower thicknesses and posses hexagonal polycrystalline structure at higher thickness, having lattice parameters a=4.44 Å and c=29.40 Å. The grain size of the Bi2Te3 thin films before annealing and after annealing are found to be 100 and 160 Å, respectively. The micro-strain and the dislocation density are found to decrease after annealing. The thermogravimetry–differential thermal analysis (TG–DTA) studies revealed that the Bi2Te3 films are non-decomposable. Electrical resistivity, TCR measurements have been carried out as a function of varying temperatures in the range 303–453 K are found to show the size effect. Analyzing the size dependence of electrical resistivity it is found that the electrical resistivity is a linear function of the reciprocal of thickness of the film. The energy gap of Bi2Te3 thin film was calculated from the graph ln ρ vs. 1/T and it is found that the energy gap decreases with increasing thickness. From the negative values of TCR, it is inferred that Bi2Te3 films exhibit semiconducting behavior. 相似文献
11.
J. Aguilar-Hernndez J. Sastr-Hernndez R. Mendoza-Prez G. Contreras-Puente M. Crdenas-García J. Ortiz-Lpez 《Solar Energy Materials & Solar Cells》2006,90(6):704-712
We have grown CdS films by the Close Spaced Vapor Transport technique under specific conditions: substrate temperature (Ts): 450 °C, source temperature (Tso): 725 °C, argon pressure in the chamber (PAr): 100, 200 and 500 mT, deposition time (td): 100 s. The films were studied by measuring the luminescence properties at different temperatures in the range 10–300 K. The room-temperature PL spectrum of the as-grown CdS films showed a very broad band centered at 2.26 eV and a shoulder in the low-energy side at 1.80 eV. After CdCl2 thermal annealing at 300 K, the spectrum showed better PL characteristics: a strong band in the low-energy side at 1.67 eV and a band in the high-energy side at 2.47 eV. The analysis at lower temperatures showed that the high-energy band becomes most intense and shifts to higher energies reaching a value of 2.54 eV, very close to the energy band gap at 10 K. The low-energy band becomes broader and centered around 1.9 eV. Analysis of the PL intensity as a function of temperature in an Arrhenius representation, allows applying a theoretical model for the quenching of the PL intensity. 相似文献
12.
A. Ennaoui B.R. Sankapal V. Skryshevsky M.Ch. Lux-Steiner 《Solar Energy Materials & Solar Cells》2006,90(10):1533-1541
Simple soft-solution method has been developed to synthesize films and powders of TiO2 and mixed TiO2–SiO2 at relatively low temperatures. This method is simple and inexpensive. Furthermore, reactor can be designed for large-scale applications as well as to produce large quantities of composite powders in a single step. For the preparation of TiO2, we used aqueous acidic medium containing TiOSO4 and H2O2, which results in a peroxo-titanium precursor while colloidal SiO2 has been added to the precursor for the formation of TiO2–SiO2. Post annealing at 500 °C is necessary to have anatase structure. Resulting films and powders were characterized by different techniques. TiO2 (anatase) phase with (1 0 1) preferred orientation has been obtained. Also in TiO2–SiO2 mixed films and powders, TiO2 (anatase) phase was found. Fourier transform infrared spectroscopy (FTIR) results for TiO2 and mixed TiO2–SiO2 films have been presented and discussed. The method developed in this paper allowed obtaining compact and homogeneous TiO2 films. These compact films are highly photoactive when TiO2 is used as photo anode in an photoelectrochemical cell. Nanoporous morphology is obtained when SiO2 colloids are added into the solution. 相似文献
13.
The CdTe thin films electrodeposited on stainless steel substrates were annealed in air at various temperatures and time durations in order to investigate the influence of post-deposition heat treatments on the grain growth of the films. The recrystallization process at lower annealing temperature is different from that of the high-temperature annealing. The annealing at lower temperature promotes better grain growth by maintaining the preference for the (1 1 1) plane. In general the grain size increases due to annealing and the recrystallization happens in three phases. The grain growth exponent is a function of temperature and time. In the beginning of the annealing, irrespective of the annealing temperatures the grain growth obeys the ideal parabolic law and for longer annealing times it deviates from the ideal case. 相似文献
14.
Kun-Mu Lee Vembu Suryanarayanan Kuo-Chuan Ho 《Solar Energy Materials & Solar Cells》2007,91(15-16):1416-1420
The influences of annealing temperature and different poly (ethylene glycol) (PEG) contents in nano-crystalline TiO2 electrodes with and without N3 dye on the electron transfer in a dye-sensitized solar cell (DSSC) were investigated. It is found that the power conversion efficiency increases with the increase in annealing temperature and becomes saturated at 400–500 °C, and further increase lowers the performance which is consistent with the enhancement of the crystalline TiO2 particles observed in X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images. Electrochemical impedance spectroscopy (EIS) also confirms this behavior. These results have been further verified by studying the electron lifetimes (τe) and electron diffusion coefficients (De) of a bare TiO2 and a dye-sensitized TiO2 film using a pulsed laser spectrometer. It is noted that both the electron lifetime and the electron diffusion coefficient increase with the increase in annealing temperature. However, the evolution of rutile TiO2 begins beyond 600 °C and this lowers the dye absorbance and the electron diffusion coefficients of TiO2 electrodes. A similar study was made by varying the content of the PEG in the TiO2 films. It is found that with the increase in the PEG content, a decrease in the electron lifetimes and a little hike in the electron diffusion coefficients are noted, where the cell performance remains almost the same. In addition, the dye adsorption decreases the electron lifetime and increases the electron diffusion coefficient of the TiO2 films regardless of the PEG content and the annealing temperature. 相似文献
15.
R. Sreekumar R. Jayakrishnan C. Sudha Kartha K.P. Vijayakumar Y. Kashibawa T. Abe 《Solar Energy Materials & Solar Cells》2006,90(17):2908-2917
Thin films of indium selenide were prepared by annealing Indium/Selenium stack layers at different temperatures ranging from 100 to 400 °C. Structural and optical characterizations were done using X-ray diffraction and optical absorption studies, respectively. Compositional analysis was done by employing Rutherford backscattering spectroscopy and X-ray photoelectron spectroscopy confirmed the compound formation. Photosensitivity and sheet resistance of these samples were also determined at room temperature. It was found that multi-phased films were formed at lower annealing temperatures and single phase films at higher annealing temperatures. A structural re-orientation as well as a phase transformation from β-In2Se3 to γ-In2Se3 was observed on annealing at 400 °C. 相似文献
16.
D. Gracin K. Juraic A. Gajovic P. Dubcek C. Devilee H.J. Muffler W.J. Soppe S. Bernstorff 《Renewable Energy》2008,33(2):326
Thin silicon films were deposited by the plasma-enhanced chemical vapour deposition method using microwave (MW) and standard radio frequency (RF) gas discharge in silane gas diluted by hydrogen in the range that produces a mixture of amorphous and crystalline phases. The samples were analysed by Raman spectroscopy and grazing incidence small-angle X-ray scattering (GISAXS), while the threshold for the transition between the amorphous and crystalline phase was checked by the change in electrical conductivity. The crystalline fraction, estimated by Raman spectroscopy, varied between 0% and 70% while the individual crystal sizes were between 3 and 9 nm. However, the size distribution was broad suggesting also the existence of smaller and larger crystals.The “particles” observed by GISAXS, most probably voids, were in the range between 2 and 12 nm. The voids in samples deposited by MW plasma were larger when closer to the surface. Their shape indicated the formation of a columnar structure perpendicular to the surface, more pronounced at higher temperature. The samples deposited by RF plasma and low power had spherically symmetric “particles” with uniform size across the depth of the samples. An increase of the RF power resulted in the formation of a columnar structure parallel to the surface. The observed differences are discussed in relation to the difference in growing kinetics of the used deposition methods. 相似文献
17.
A. Turkovi Z. Crnjak-Orel P. Dub
ek H. Amenitsch 《Solar Energy Materials & Solar Cells》1999,59(4):387
Titanium dioxide, micelles on glass substrate were generated in situ in a water-in-oil (w/o) microemulsion composed of water, dioctyl sulfosuccinate sodium salt (AOT), and cyclohexane, by controlled hydrolysis of TiCl4. The average grain size R, obtained by grazing-incidence small-angle X-ray scattering (GISAXS), was 6.3±0.8 nm. “Corrected specific surface” of TiO2 micelles was determined as 5.0×105 cm−1. The average grain size R of 5.0±1.3 nm obtained by grazing-incidence wide-angle X-ray scattering (GIWAXS) agrees with GISAXS value. GIWAXS can detect smaller amounts of additional phases or impurities than classical X-ray diffraction equipment. 相似文献
18.
A series of CdS1−xSex thin films have been deposited on fluorine doped tin oxide (FTO) coated glass substrates by chemical bath deposition. The influences of S/Se ratio in the precursor solution and annealing treatment on the structural, morphological, compositional, optical, and photoelectrochemical properties of the films were investigated. X-ray diffraction patterns revealed that the hexagonal cadmium cyanamide and the solid solutions of CdS1−xSex were formed. The morphological and compositional studies indicated that the thin film was composed of cadmium cyanamide sheets in the upper layer and CdS1−xSex spherical grains in the underlying layer. The optical absorption studies revealed that the band gap of unannealed and annealed films varied from 2.4 eV to 1.94 eV and from 2.35 eV to 1.67 eV as x increased from 0 to 1, respectively. The photo responses well agreed with the optical absorption of these films. The annealed CdSe shows the best photoresponse with a photon-to-current efficiency of 1.69% at 0.27 V (versus SCE). 相似文献
19.
S. Niki I. Kim P. J. Fons H. Shibata A. Yamada H. Oyanagi T. Kurafuji S. Chichibu H. Nakanishi 《Solar Energy Materials & Solar Cells》1997,49(1-4)
CuInSe2 (CIS) thin films with a range of Cu/In ratios were grown by molecular beam epitaxy on GaAs (0 0 1) at substrate temperatures of Ts = 450–500°C and the effects of annealing under various atmospheres have been investigated. Photoluminescence spectra obtained from an ex-situ vacuum annealed CIS film at a temperature of TA = 350°C showed a red-shift and a broadening of an emission peak (peak c) which originally appeared at 0.970 eV before annealing and the red-shifted peak c was found to consist of two overlapping peaks. The excitation power dependence of these overlapping peaks indicated the radiative recombination processes associated with the emissions to be a conduction band to acceptor transition (peak at 0.970 eV) and a transition due to donor-acceptor pairs (peak at 0.959 eV), indicating the formation of a shallow donor-type defect during the vacuum annealing process. The origin of this defect has tentatively been attributed to Se vacancies. On the other hand, the molar fraction of oxygen increased with increasing annealing temperature in dry-air. An epitaxially grown In2O3 phase was found both in Cu-rich and In-rich films annealed at TA 350°C, which was not observed in the films annealed in Ar atmosphere. Thermodynamic calculations based on the Cu---In---Se---O---N system showed In2O3 to be the most stable phase in good agreement with the experimental results. 相似文献
20.
Vanadium and tantalum-doped vanadium pentoxide, V2O5 and V2O5:Ta thin films (2.5 and 5 mol% of Ta) were prepared using sol–gel dip-coating technique.The coating solutions were prepared by reacting vanadium (V) oxytripropoxide and tantalum ethoxide (V) as precursors using anhydrous isopropyl alcohol as solvent.The films were deposited on a transparent glass substrate with ITO conducting film by dip-coating technique, with a withdrawal of 20 cm/min from the vanadium–tantalum solution and heat treated at 300 °C for 1 h. The resulting films were characterized by cyclic voltammetry, optical spectroscopy and by X-ray diffraction analysis (XRD). XRD data show that the films thermally treated at 300 °C were crystalline.A charge density of 70 mC/cm2 was obtained for the film with 5 mol% of Ta, with an excellent stability up to 1500 cycles. 相似文献