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1.
Fluorine-doped ZnO transparent conductive thin films were successfully deposited on glass substrate by radio frequency magnetron sputtering of ZnF2. The effects of rapid thermal annealing in vacuum on the optical and electrical properties of fluorine-doped ZnO thin films have been investigated. X-ray diffraction spectra indicate that no fluorine compounds, such as ZnF2, except ZnO were observed. The specimen annealed at 500 °C has the lowest resistivity of 6.65 × 10? 4 Ω cm, the highest carrier concentration of 1.95 × 1021 cm? 3, and the highest energy band gap of 3.46 eV. The average transmittance in the visible region of the F-doped ZnO thin films as-deposited and annealed is over 90%.  相似文献   

2.
Ga doped ZnO (GZO) and GaP codoped ZnO (GPZO) thin films of different concentrations (1–4 mol%) have been grown on sapphire substrates by RF sputtering for the fabrication of ZnO homojunction. The grown films have been characterized by X-ray diffraction (XRD), photoluminescence (PL), Hall measurement, energy dispersive spectroscopy (EDS), time-of-flight secondary ion mass spectrometer (ToF-SIMS), UV–Vis–NIR spectroscopy and atomic force microscopy (AFM). Unlike in conventional codoping, here we directly doped (codoped) GaP into ZnO to realize p-ZnO. The Hall measurements indicate that 2 and 4% GPZO films exhibit p-conductivity due to the sufficient amount of phosphorous incorporation while all the monodoped GZO films showed n-conductivity as expected. Among the p-ZnO films, 2% GPZO film shows low resistivity (2.17 Ωcm) and high hole concentration (1.8 × 1018 cm?3) by optimum incorporation of phosphorous due to best codoping. Similarly, among the n-type films, 2% GZO shows low resistivity (1.32 Ωcm) and high electron concentration (2.02 × 1019 cm?3) by optimum amount of Ga incorporation. The blue shift and red shift in NBE emission observed from PL acknowledged the formation of n- and p-conduction in monodoped and codoped films, respectively. The neutral acceptor bound exciton recombination (A0X) observed by low temperature PL for 2% GPZO confirms the p-conductivity. Further, the high concentration of P atoms than Ga observed from ToF-SIMS (2% GPZO) also supports the p-conductivity of the films. The fabricated p–n junction with best codoped p-(ZnO)0.98(GaP)0.02 and best monodoped n-Zn0.98Ga0.02O films showed typical rectification behavior of a diode. The diode parameters have also been estimated for the fabricated homojunction.  相似文献   

3.
Zinc oxide thin films have been obtained by pulsed laser ablation of a ZnO target in O2 ambient at a pressure of 0.13 Pa using a pulsed Nd:YAG laser. ZnO thin films deposited on Si (1 1 1) substrates were treated at annealing temperatures from 400 °C up to 800 °C after deposition. The structural and optical properties of deposited thin films have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra, resistivity and IR absorption spectra. The results show that the obtained thin films possess good single crystalline with hexagonal structure at annealing temperature 600 °C. Two emission peaks have been observed in photoluminescence spectra. As the post-annealing temperature increase, the UV emission peaks at 368 nm is improved and the intensity of blue emission at 462 nm decreases, which corresponds to the increasing of the optical quality of ZnO film and the decreasing of Zn interstitial defect, respectively. The best optical quality for ZnO thin films emerge at post-annealing temperature 600 °C in our experiment. The measurement of resistivity also proves the decrease of defects of ZnO films. The IR absorption spectra of sample show the typical Zn–O bond bending vibration absorption at wavenumber 418 cm−1.  相似文献   

4.
《Materials Research Bulletin》2013,48(4):1397-1402
0-3 type ZnO/Bi3.6Eu0.4Ti3O12 (BEuT) nanocomposite films with ZnO nanopowders in BEuT host were prepared by chemical solution deposition. The effects of ZnO content on the structure, photoluminescence, and electrical properties of the films were investigated. The ZnO/BEuT molar ratio strongly affected the grain size and growth orientation of BEuT, dielectric and ferroelectric properties, as well as emission intensity. The nanocomposite films showed strong red emission peaks due to 5D0  7F1 and 5D0  7F2 transitions of Eu3+ ions. Good electrical properties with high dielectric constant of 480 (at 1 kHz) and large remanent polarization (2Pr) of 32 μC/cm2 were obtained for the nanocomposite films having a ZnO/BEuT molar ratio of 1:2. The mechanisms for enhanced photoluminescence and electric properties were discussed. The results suggest that the nanocomposite thin films are promising candidate materials for multifunctional optoelectronic devices.  相似文献   

5.
We report, the effect of air annealing on solar conversion efficiency of chemically grown nanostructured heterojunction thin films of CdS/CuInSe2, such 100, 200 and 300 °C air annealed thin films characterized for physicochemical and optoelectronic properties. XRD pattern obtained from annealed thin films confirms tetragonal crystal geometry of CuInSe2 and an increase in average crystallite size from 16 to 32 nm. An EDAX spectrum confirms expected and observed elemental composition in thin films. AFM represents high energy induced grain growth and agglomeration due to polygonization process. Increase in optical absorbance strength and decrease in energy band gap from 1.36 to 1.25 eV is observed. Increase in charge carrier concentration from 2 × 1016 to 8 × 1017 cm?3 is observed as calculated from Hall effect measurements and an enhancement in solar conversion efficiency from 0.26 to 0.47% is observed upon annealing.  相似文献   

6.
Zinc oxide (ZnO) was synthesized using a microwave assisted hydrothermal (MAH) process based on chloride/urea/water solution and under 800 W irradiation for 5 min. In the bath, Zn2+ ions reacted with the complex carbonate and hydroxide ions to form zinc carbonate hydroxide hydrate (Zn4CO3(OH)6·H2O), and the conversion from Zn4CO3(OH)6·H2O to ZnO was synchronously achieved by a MAH process. The as-prepared ZnO has a sponge-like morphology. However, the initial sponge-like morphology of ZnO could change to a net-like structure after thermal treatment, and compact nano-scale ZnO particles were finally obtained when the period of thermal treatment increased to 30 min. Pure ZnO nanoparticles was obtained from calcination of loose sponge-like ZnO particles at 500 °C. The analysis of optical properties of these ZnO nanoparticles showed that the intensity of 393 nm emission increased with the calcination temperature because the defects were reduced and the crystallinity was improved.  相似文献   

7.
《Materials Letters》2007,61(14-15):3030-3036
Transparent conducting thin films of F:SnO2 have been deposited onto preheated glass substrates by a spray pyrolysis technique using pentahydrate stannic chloride (SnCl4·5H2O) and ammonium fluoride (NH4F) as precursors and mixture of water and propane-2-ol as solvent. The concentration of SnCl4·5H2O and NH4F is kept fixed and the ratio of water and propane-2-ol solvent in the spraying solution is varied. A fine spray of the source solution using air as a carrier gas has grown films of thickness up to 995 nm. Optical absorption, X-ray diffraction, Van der Pauw technique for measurement of a sheet resistance and Hall effect measurements at room temperature for determination of carrier density and conductivity have been used. The as-deposited films are of polycrystalline SnO2 with a tetragonal crystal structure and are preferentially having orientation along the (200) direction with texture coefficient as high as 6.16. The average grain size for the as-deposited sample is found to be of the order of 44 nm. The films have moderate optical transmission (up to 70–85% at 550 nm). The figure of merit (ϕ) values vary from 1.95 · 10 3 to 35.68 · 10 3 Ω 1. The films are heavily doped, degenerate and exhibit n-type electrical conductivity. The lowest sheet resistance (Rs) for the optimized sample is 5.1 Ω. The films have a resistivity of 5.43 · 10 4 Ω cm and mobility around 7.38 cm2 V 1 s 1.  相似文献   

8.
Ca2MgSi2O7:Eu3+ films were deposited on Al2O3 (0 0 0 1) substrates by pulsed laser deposition. The films were grown at various oxygen pressures ranging from 100 to 400 mTorr. The crystallinity and surface morphology of the films were examined by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. XRD and AFM respectively showed that the Ca2MgSi2O7:Eu3+ films had a zircon structure and consisted of homogeneous grains ranging from 100 to 400 nm depending on the deposition conditions. The radiation emitted was dominated by a red emission peak at 620 nm. The maximum PL intensity of the Ca2MgSi2O7:Eu3+ films grown at 300 mTorr was increased by a factor of 1.3 compared to that of Ca2MgSi2O7:Eu3+ films grown at 100 mTorr. The crystallinity, surface roughness and photoluminescence of the thin-film phosphors were strongly dependent on the deposition conditions, in particular, the oxygen partial pressure.  相似文献   

9.
Spray pyrolysis method is used to deposit lanthanum telluride (La2Te3) thin films on glass substrates. The films are deposited by pyrolysis of sprayed solutions of LaCl3 and Te metal dissolved in concentrated HCl and HNO3 along with hydrazine hydrate as a reducing agent. X-ray diffraction analyses show that the films are polycrystalline with La2Te3 phase. The films have a direct optical band gap of 2.2 eV. The films are p-type semiconductors with an electrical resistivity of the order of 104 Ω cm at ambient temperature (27 °C).  相似文献   

10.
《Thin solid films》2006,494(1-2):42-46
Amorphous Zn–Sn–O (ZTO) thin films with relative Zn contents (= [at.% Zn]/([at.% Zn] + [at.% Sn])) of 0, 0.08 and 0.27 were fabricated by co-sputtering of SnO2 and ZnO targets at room temperature. Changes in structural, electrical and optical properties together with electron transport properties were examined upon post-annealing treatment in the temperature range from 200 to 600 °C in vacuum and in air. Characterization by XRD showed that an amorphous ZTO thin film crystallized at higher temperatures with increasing Zn content. Crystallized ZTO films with a relative Zn content of 0.27 might not contain a single SnO2 phase which is observed in the films of the other compositions. Amorphous ZTO films showed decreasing electrical resistivities with increasing annealing temperature, having a minimum value of 1 × 10 3 Ω cm. Upon crystallization, the resistivities increased drastically, which was attributed to poor crystallinity of the crystallized films. All the ZTO films were found to be degenerate semiconductors with non-parabolic conduction bands having effective masses varying from 0.15 to 0.3 in the carrier concentration range of 6 × 1018 to 2 × 1020 cm 3. As for a ZTO film with a relative Zn content of 0.27, the degree of non-parabolicity was much lower compared with films of the other compositions, leading to a relatively stable mobility over a wide range of carrier concentration.  相似文献   

11.
《Optical Materials》2005,27(3):419-423
Nanocrystalline ZnS films have been prepared by sulfidation of the reactive magnetron sputtered ZnO films. The structure, composition and optical properties of the sulfurized ZnO films as a function of the sulfidation temperature (TS) have been systematically studied. It is found that at TS  400 °C ZnO is completely converted to ZnS with the hexagonal structure. The ZnS films have a strongly (0 0 2) preferred orientation and an optical transparency of about 80% in the visible region. In addition, at TS < 444.6 °C (boiling point of sulfur), some residual sulfur decomposed from H2S gas can adhere to the sulfurized film surface while at TS = 580 °C a S/Zn ratio much higher than the ideal stoichiometric proportion of ZnS is obtained for the ZnS films. ZnS films with a minimum XRD FWHM value of 0.165° and a good S/Zn ratio of 0.99 are obtained at a temperature of 500 °C indicating the ZnS films to be suitable for use in the thin film solar cells.  相似文献   

12.
《Materials Research Bulletin》2013,48(11):4596-4600
In this paper, the growth of n-type aluminum boron co-doped ZnO (n-AZB) on a p-type silicon (p-Si) substrate by sol–gel method using spin coating technique is reported. The n-AZB/p-Si heterojunctions were annealed at different temperatures ranging from 400 to 800 °C. The crystallite size of the AZB nanostructures was found to vary from 28 to 38 nm with the variation in annealing temperature. The band gap of the AZB decreased from 3.29 to 3.27 eV, with increasing annealing temperature from 400 to 700 °C and increased to 3.30 eV at 800 °C probably due to the formation of Zn2SiO4 at the interface. The band gap variation is explained in terms of annealing induced stress in the AZB. The n-AZB/p-Si heterojunction exhibited diode behavior. The best rectifying behavior was exhibited at 700 °C.  相似文献   

13.
Variable-energy positron annihilation spectroscopy has been applied to the study of defects in TiO2/p+-Si structures, in the as-grown state and after annealing in vacuum and in hydrogen, to investigate whether annealing (and film thickness) resulted in an increase of vacancy-type defects in the oxide films. It was found that the concentration of such defects remained unchanged after vacuum annealing for all films studied, but after H2 annealing more than doubled for 150 nm-thick films, and increased by an order of magnitude for 100 nm-thick films. The nature of the vacancies was examined further by measuring high-precision annihilation lines and comparing them with a reference Si spectrum. The changes observed in the ratio spectra associated with oxygen electrons suggest that the defects are oxygen vacancies, which have been shown to enhance electroluminescence from TiO2/p+-Si heterostructure-based devices.  相似文献   

14.
In this paper we introduce mechanical and structural characteristics of diamond-like carbon (DLC) films which were prepared on silicon substrates by radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) method using methane (CH4) and hydrogen (H2) gas. The films were annealed at various temperatures ranging from 300 to 900 °C in steps of 200 °C using rapid thermal processor (RTP) in nitrogen ambient. Tribological properties of the DLC films were investigated by atomic force microscopy (AFM) in friction force microscopy (FFM) mode. The structural properties of the films were obtained by high resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The wettability of the films was obtained using contact angle measurement. XPS analysis showed that the sp3 content is decreased from 75.2% to 24.1% while the sp2 content is increased from 24.8% to 75.9% when the temperature is changed from 300 to 900 °C. The contact angles of DLC films were higher than 70°. The FFM measurement results show that the highest friction coefficient value was achieved at 900 °C annealing temperature.  相似文献   

15.
We have studied the influence of oxygen partial pressure (OPP; 250 mTorr–1 × 10?5 Torr) and Fe doping (2 and 4 at.%) on structural and electrical properties of TiO2 thin films on LaAlO3 substrates. X-ray photoelectron spectroscopy suggests that Fe is not in metal cluster form. It is found that the evolution of the three phases; anatase, rutile and brookite of TiO2 as well as the magneli phase (TinO2n?1) strongly depends on the OPP and Fe doping concentration. All the films grown at 250 mTorr show insulating behavior, whereas films grown at 1 × 10?2 and 1 × 10?4 Torr reveal high temperature metallic to low temperature semiconducting transition. Interestingly, films deposited at 1 × 10?5 Torr reveal charge ordering, which is contributed to the magneli phase of TiO2. The present study suggests that functionality of TiO2 thin film based devices can be tuned by properly selecting the OPP and dopant concentration.  相似文献   

16.
Biaxially textured CeO2-based oxide films with crack-free and smooth surface were prepared by metal-organic deposition (MOD) on Ni-W alloy tapes after annealing. In this study, addition of B2O3-based precursors to precursor solution and their effects on crystallinity and surface roughness of the CeO2-based oxide films were investigated. As the amount of added B2O3-based precursors increased, the relative intensity of CeO2 (200) peak was monotonously increased and much smoother surface was obtained. Microcracks in CeO2 films were successfully suppressed by substituting gadolinium for part of cerium in the CeO2 films. In addition to this, a biaxially textured Ce0.75Gd0.25O2-4.5% B2O3 film (Δθ = 4.8°, Δ? = 7.4°) with smooth surface (Rq = 2.7 nm) was successfully grown on the Ni-W tape after annealing at 900 °C.  相似文献   

17.
The effect of different annealing atmospheres (H2, air, Ar and N2) on precipitated phases, corrosion resistance and hardness of Al86Ni9La5 amorphous alloy was investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetry (TG), electrochemistry experiment and microhardness tester. During annealing at 523 K, the primary crystallized fcc-Al is independent on the annealing atmospheres. During annealing at 584 K, the final crystalline phases, i.e. fcc-Al + Al11La3 + Al3Ni, are also independent on the different annealing atmospheres. However, during annealing at 523 K, H2 and air can promote the eutectic crystallization process, and induce the formation of metastable Al3Ni2 phase. The promoting effect of different annealing atmospheres is in the order of H2 > air > Ar > N2. The microhardness and corrosion resistance in the 3.5 wt.% NaCl solution are improved by annealing in H2 and air atmospheres. The property promotion caused by annealing process can be ascribed to the formation of nanocrystalline phases, which is possibly helpful to develop the alloy's application in the seawater environment.  相似文献   

18.
Bio-nanocomposite films based on chitosan and manganese oxide nanoflake have been fabricated via the layer-by-layer (LBL) self-assembly technique. UV–vis absorption spectra showed that the subsequent growth of the nanocomposite film was regular and highly reproducible from layer to layer. X-ray photoelectron spectroscopy (XPS) spectra confirmed the incorporation of chitosan and manganese oxide nanoflake into the films. Scanning electron microscopy (SEM) images revealed that the nanocomposite film had a continuous surface and a layered structure. A sensitive hydrogen peroxide (H2O2) amperometric sensor was fabricated with the chitosan–manganese oxide nanoflake nanocompoite film. The sensor showed a rapid and linear response to H2O2 over the range from 2.5 × 10? 6 to 1.05 × 10? 3 M, with a sensitivity of 0.038 A M? 1 cm? 2.  相似文献   

19.
FePt multilayer films were deposited on Si(1 0 0) substrate with thermally grown SiO2 film and sputtered Ag underlayer at room temperature by dc magnetron sputtering and subsequently annealing in vacuum. Experimental results suggest that proper thickness of Ag underlayer and slightly rich of Fe content can effectively induce the (0 0 1) texture of FePt films. A Fe57.4Pt42.6 thin film on the 8 nm Ag underlayer exhibits a large perpendicular coercivity of 7.6 kOe with magnetic remanence close to 1.  相似文献   

20.
《Materials Letters》2007,61(11-12):2299-2302
Homoepitaxial ZnO films have been grown via liquid-phase epitaxy (LPE) on (0001) oriented ZnO substrates. X-ray rocking curve revealed the high quality of the ZnO films with a FWHM of 40 arc sec. Films of thickness about 20 μm were grown in the temperature range 700–720 °C. The growth rate of ZnO films was estimated to be 0.3 μm h 1. Atomic force microscope analysis showed that the surface roughness of ZnO films was very low, which further confirmed the high crystallinity of ZnO films.  相似文献   

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