A comprehensive study on the effects of alternative sulphur precursor on the material properties of chemical bath deposited CdS thin films

Chemical bath deposition (CBD) method was used to deposit CdS thin films on soda-lime glass substrates by using n-methylthiourea (NTU) as an alternative sulphur source and were compared to typical thiourea (TU) precursor. The sulphur source concentration was varied from 0.01 M to 0.1 M and the impact on the microstructural, surface morphology, optical and electrical properties of the grown films were studied. Increasing n-methylthiourea concentration in the precursor yielded thinner films that are less than 100 nm thickness, surface morphology with average surface roughness of 6.4 nm, larger granular structure, wider band gap at 2.3 eV–2.6 eV range. Raman spectroscopy revealed Raman peak at 303 cm-1. In contrast, an increase in thiourea concentration resulted in thinner amorphous films, less distinct granular structure, narrower energy band gap from 2.3 eV to 2.4 eV and a resonance Raman peak at 302 cm-1. CdS thin film deposited from n-methylthiourea precursor at higher precursor concentration of 0.1 M showed better electrical properties such as lower resistivity and higher carrier mobility compared to the thin film deposited from typical thiourea precursor.     

Optimization of Opto-Electrical and Photocatalytic Properties of SnO<Subscript>2</Subscript> Thin Films Using Zn<Superscript>2+</Superscript> and W<Superscript>6+</Superscript> Dopant Ions

Abstract  

A series of Zn²⁺ and W⁶⁺ doped tin oxide (SnO₂) thin films with various dopant concentrations were prepared by spray pyrolysis deposition, and were characterized by X-ray diffraction, atomic force microscopy, contact angle, absorbance, current density–voltage (J–V) and photocurrent measurements. The results showed that W⁶⁺ doping can prevent the growth of nanosized SnO₂ crystallites. When Zn²⁺ ions were used, the crystallite sizes were proved to be similar with the undoped sample due to the similar ionic radius between Zn²⁺ and Sn⁴⁺. Regardless of the dopant ions’ type or concentration, the surface energy has a predominant dispersive component. By using Zn²⁺ dopant ions it is possible to decrease the band gap value (3.35 eV) and to increase the electrical conductivity. Photocatalytic experiments with methylene blue demonstrated that with zinc doped SnO₂ films photodegradation efficiencies close to 30% can be reached.     

Electrodeposition of ZnSe

The conditions of the electrodeposition of a thin film of polycrystalline ZnSe phase on copper substrate from aqueous baths were studied. The electrochemical behavior of Zn²⁺ and H₂SeO₃ species was investigated using cyclic voltammetry. Thin films were deposited potentiostatically on copper substrate and the influence of deposition parameters such as deposition potential, H₂SeO₃ and ZnSO₄ concentration, and temperature of bath on the crystallinity and on the chemical composition of the film is discussed. The ZnSe layers were characterized by X-ray diffraction, X-ray energy dispersive spectroscopy and scanning electron microscopy.     

Electrodeposition of PbTe thin films from acidic nitrate baths

Electrodeposition of PbTe thin films from an acidic nitric bath was systematically investigated to understand the kinetics and the effect of electrodeposition conditions on film composition, crystallographic structure, texture and grain size. The electroanalytical studies employed initially with a rotating disk electrode to investigate the kinetics associated with Te, Pb and PbTe electrodeposition. The results indicated that the PbTe thin films were obtained by the underpotential deposition (UPD) of Pb atoms onto the overpotentially deposited Te atoms on a substrate.Based on these studies, PbTe thin films were potentiostatically electrodeposited using e-beam evaporated gold thin films on silicon substrate to investigate the effect of various deposition conditions on film composition and microstructure. The data indicated that the microstructure, composition and preferred film growth orientation of PbTe thin films strongly depended on the applied potential and electrolyte concentration. At −0.12 V, the film was granular, dense, and preferentially oriented in the [1 0 0] direction. At potentials more negative than −0.15 V, the film was dendritic and preferentially oriented in the [2 1 1] direction. A smooth, dense and crystalline film with nearly stoichiometric composition was obtained at −0.12 V from a solution containing 0.01 M HTeO₂⁺, 0.05 Pb²⁺ and 1 M HNO₃.     

Electro-optical performances of nanostructured SrTiOx films: The effect of plasma power,Ar/O2 ratio and annealing

The present work evaluates the effects of plasma power and oxygen mixing ratios (OMRs) on structural, morphological, optical, and electrical properties of strontium titanate SrTiO_x (STO) thin films. STO thin films were grown by magnetron sputtering, and later thermal annealing at 700°C for 1 h was applied to improve film properties. X-ray diffraction analysis indicated that as-deposited films have amorphous microstructure independent of deposition conditions. The films deposited at higher OMR values and later annealed also showed amorphous structure while the films deposited at lower OMR value and annealed have nanocrystallinity. In addition, all as-deposited films were highly transparent (~80%–85%) in the visible spectrum and exhibited well-defined main absorption edge, while the annealing improved transparency (90%) within the same spectrum. The calculated direct and indirect optical band gaps for films were in the range of 3.60-4.30 eV as a function of deposition conditions. The refractive index of the films increased with OMRs and the postdeposition annealing. The frequency dependent capacitance measurements at 100 kHz were performed to obtain film dielectric constant values. High dielectric constant values reaching up to 100 were obtained. All STO samples exhibited more than 2.5 μC/cm² charge storage capacity and low dielectric loss (less than 0.07 at 100 kHz). The leakage current density was relatively low (3 × 10⁻⁸Acm⁻² at +0.8 V) indicating that STO films are promising for future dynamic random access memory applications.     

Characterization of Bi2O3 thin films for doping photoluminescent Er3+ ions

Undoped and Er³⁺-doped Bi₂O₃ thin films were sputter-deposited on Si(100) substrates. Sufficiently oxidized Bi₂O₃ films with refractive indices between 2.17?2.23 were obtained at a wavelength of 633 nm; these values are comparable to those of bulk Bi₂O₃ crystals. While the film composition was stable for deposition temperatures between room temperature (RT) and 450 °C, the refractive index steeply decreased above 450 °C and reached 1.4 at 600 °C. The lowering of the optical transmittance spectra indicated aggregation of metallic Bi and darkening of the film. All films exhibited X-ray diffraction patterns of α-Bi₂O₃. The direct and indirect bandgap energies derived from the Tauc plots were 3.4–3.7 eV and 1.9–2.5 eV, respectively, depending on the O₂ flow rate and deposition temperature. Upon excitation of Er³⁺-doped Bi₂O₃ films at 532 nm, Er³⁺ emissions peaking at 1537 and 1541 nm appeared, and the photoluminescence spectra included fine structures reflecting crystal-field splitting. Resonant excitation of Er³⁺ 4f levels and indirect excitation via the defect levels of Bi₂O₃ followed by energy transfer to Er³⁺ contributed to the emission. The films deposited at RT with Er concentrations of 2 at.% had the emission intensity of Er³⁺, but concentration quenching strongly suppressed the Er³⁺ emission because the doped Er³⁺ ions stayed inside the Bi₂O₃ crystals. At deposition temperatures above 400 °C, the concentration quenching was mitigated possibly because out-diffusion of Er³⁺ ions reduced the effective number of Er³⁺ ions in the Bi₂O₃ crystalline domains.     

Characterization of indium tin oxide (ITO) thin films prepared by a sol-gel spin coating process

Indium tin oxide (ITO) thin films were prepared by a sol-gel spin coating method, fired, and then annealed in the temperature range of 450-600°. The XRD patterns of the thin films indicated the main peak of the (2 2 2) plane and showed a higher degree of crystallinity with an increase in the annealing temperature. Upon annealing the films at 500 and 600°, two binding energy levels of Sn⁴⁺ ion of 486.9 eV and 486.6 eV, respectively, were measured in the XPS spectra. The ITO film that was annealed at 600° contained two oxidation states of Sn, Sn²⁺ and Sn⁴⁺, and it had a higher sheet resistance based on a rather low doping concentration of Sn⁴⁺. The film that was annealed at 500° and subsequently treated with 0.1 N HCl solution for 40 s showed a sheet resistance of 225 Ω/square. The surface treatment by the acidic solution diminished the RMS (root mean square) roughness value and the residual carbon content (XPS peak intensity of carbon) of the ITO films. It seems that the acid-cleaning of the ITO thin films led to a decrease of the surface roughness and sheet resistance.     

Structural,optical and electrical properties of indium doped Cu2ZnSn(S,Se)4 thin films synthesized by the DC and RF reactive magnetron cosputtering

Element doping into the Cu₂ZnSn(S,Se)₄ (CZTSSe) absorber is an effective method to optimize the performance of thin film solar cells. In this study, the Cu₂In_xZn_1-xSn(S,Se)₄ (CIZTSSe) precursor film was deposited by magnetron cosputtering technique using indium (In) and quaternary Cu₂ZnSnS₄ (CZTS) as targets. Meanwhile, the In content was controlled using the direct current (DC) power on In target (P_In). A single kesterite CIZTSSe alloy was formed by successfully doping a small number of In³⁺ into the main lattice of CZTSSe. The partial Zn²⁺ cations were substituted by In³⁺ ions, resulting in improving properties of CZTSSe films. Morphological analysis showed that large grain CIZTSSe films could be obtained by doping In. The well-distributed, smooth, and dense film was obtained when the P_In was 30 W. The band gap of CIZTSSe could be continuously adjusted from 1.27 to 1.05 eV as P_In increased from 0 to 40 W. In addition, the CIZTSSe alloy thin film at P_In = 30 W exhibited the best p-type conductivity with Hall mobility of 6.87 cm²V^?1s^?1, which is a potential material as the absorption layer of high-performance solar cells.     

Enhanced electrical properties of In-Ga-Sn-O thin films at low-temperature annealing

Electrical and optical properties of In-Ga-Sn-O (IGTO) thin films deposited by radio-frequency magnetron sputtering were investigated according to annealing temperatures. While IGTO films remained an amorphous phase even after a heat treatment at temperature up to 500 °C, Hall measurements showed that annealing temperature had a significant impact on electrical properties of IGTO thin films. After investigating a wide range of annealing temperatures for samples from as-deposited state to 500 °C, IGTO film annealed at 200 °C exhibited the best electrical performance with a conductivity of 229.31 Ω^?1cm^?1, a Hall mobility of 36.89 cm²V^?1s^?1, and a carrier concentration of 3.85 × 10¹⁹ cm^?3. Changes in proportions of oxygen-related defects and percentages of Sn²⁺ and Sn⁴⁺ ions within IGTO films according to annealing temperatures were analyzed with X-ray photoelectron spectroscopy to determine the cause of the superb performance of IGTO at a low temperature. In IGTO films annealed at 200 °C, Sn⁴⁺ ions acting as donor defects accounted for a high percentage, whereas hydroxyl groups working as electron traps showed a significantly reduced percentage compared to the as-deposited film. Optical band gaps of IGTO films obtained from UV–visible spectrum were 3.38–3.47 eV. The largest band gap value of 3.47 eV for the IGTO film annealed at 200 °C could be attributed to an increase in Fermi-level due to an increase of carrier concentration in the conduction band. These spectroscopic results well matched with electrical properties of IGTO films according to annealing temperatures. Excellent electrical properties of IGTO thin films annealed at 200 °C could be largely due to Sn donors besides oxygen vacancies, resulting in a significant increase in free carriers despite a low annealing. temperature.     

Enhanced photocatalytic activity of TiO2-ZnO thin films deposited by dc reactive magnetron sputtering

The effect of deposition conditions on the photocatalytic activity of TiO₂-ZnO thin films was studied. By using a (Ti)₉₀-(Zn)₁₀ alloy target, the samples were deposited at room temperature on glass substrates by dc reactive magnetron sputtering and post-annealed in air at 500 °C. The dependence of the physical properties of the films on the O₂/Ar gas ratio and the deposition working pressure was investigated. XRD patterns showed mainly the formation of the anatase phase of TiO₂. Optical absorption measurements exhibited a blue shift of the band-gap energy with increasing working pressure. XPS spectra indicated the presence of the Ti⁴⁺ and Zn²⁺ oxidation states, which correspond to TiO₂ and ZnO, respectively. The chemical state of Ti was further analyzed by means of the modified Auger parameter, α’, which gave a value of ca. 873 eV. The photocatalytic property of the films was assessed by the degradation of a methylene blue aqueous solution. The maximum photocatalytic performance was observed for the samples deposited at 3.0 mTorr and O₂/Ar gas ratio of 10/90. These results are explained in terms of the structural, optical, and morphological properties of the films.     

Characterization of spray pyrolytically deposited high mobility praseodymium doped CdO thin films

Praseodymium (Pr) doped CdO thin films with high transparency and high mobility were deposited, using a homemade spray pyrolysis setup, on micro-slide glass substrates preheated at 300 °C. Polycrystalline nature and Cd-O bond vibration of deposited films were confirmed by X-ray diffraction, micro-Raman and Fourier transform infrared spectroscopy analyses. The oxidation state of Cd²⁺, O²⁻, and Pr³⁺ was confirmed by X-ray photoelectron spectroscopy analysis. The highest average particle size (92 nm-FESEM) and high RMS (13.48 nm-AFM) values are obtained for 0.50 wt% Pr doped CdO thin film. The optical band gap is varied between 2.38 eV and 2.52 eV, depending on the Pr doping concentration. Photoluminescence spectra revealed that Pr doped CdO thin film exhibits strong green emission at 582 nm. High mobility (82 cm²/V s), high charge carrier concentration (2.19×10²⁰ cm⁻³) and high transmittance (83%) were observed for 0.50 wt% Pr doped CdO film. A high figure of merit (9.79×10⁻³ Ω⁻¹) was obtained for 0.50 wt% Pr doped CdO thin films. The mechanism behind the above results is discussed in detail in this paper.     

Growth and properties of Cu3SbS4 thin films prepared by a two-stage process for solar cell applications

Cu₃SbS₄ is a promising material for thin film heterojunction solar cells owing to its suitable optical and electrical properties. In this paper, we report the preparation of Cu₃SbS₄ thin films by annealing the Sb₂S₃/CuS stacks, produced by chemical bath deposition, in a graphite box held at different temperatures. The influence of annealing temperature on the growth and properties of these films is investigated. These films are systematically analyzed by evaluating their structural, microstructural, optical and electrical properties using suitable characterization techniques. X-ray diffraction analysis showed that these films exhibit tetragonal crystal structure with the lattice parameters a=0.537 nm and b=1.087 nm. Their crystallite size increases with increasing annealing temperature of the stacks. Raman spectroscopy analysis of these films exhibited modes at 132, 247, 273, 317, 344, 358 and 635 cm⁻¹ due to Cu₃SbS₄ phase. X-ray photoelectron spectroscopy analysis revealed that the films prepared by annealing the stack at 350 °C exhibit a Cu-poor and Sb-rich composition with +1, +5 and −2 oxidation states of Cu, Sb and S, respectively. Morphological studies showed an improvement in the grain size of the films on increasing the annealing temperature. The direct optical band gap of these films was in the range of 0.82–0.85 eV. Hall measurements showed that the films are p-type in nature and their electrical resistivity, hole mobility and hole concentration are in the ranges of 0.14–1.20 Ω-cm, 0.05–2.11 cm² V⁻¹ s⁻¹ and 9.4×10²⁰–1.4×10¹⁹ cm⁻³, respectively. These structural, morphological, optical and electrical properties suggest that Cu₃SbS₄ could be used as an absorber layer for bottom cell in multi-junction solar cells.     

Polymeric semiconducting carbon from fullerene by pulsed laser ablation

The polymeric semiconducting carbon films are grown on silicon and quartz substrates by excimer (XeCl) pulsed laser deposition (PLD) technique using fullerene C₆₀ precursor. The substrate temperature is varied up to 300 °C. The structure and optical properties of the films strongly depend on the substrate temperature. The grain size is increased and uniform polymeric film with improved morphology at higher temperature is observed. The Tauc gap is about 1.35 eV for the film deposited at 100°C and with temperature the gap is decreased upto 1.1 eV for the film deposited at 250 °C and increased to about 1.4 eV for the film deposited at 300 °C. The optical absorption properties are improved with substrate temperature. Raman spectra show the presence of both G peak and D peak and are peaked at about 1590 cm^− 1 and 1360 cm^− 1, respectively for the film deposited at 100 °C. The G peak position remains almost unchanged while D peak has changed only a little with temperature might be due to its better crystalline structure compared to the typical amorphous carbon films and might show interesting in device such as, optoelectronic applications.     

Electrodeposition of zinc–iron alloy from an alkaline bath in the presence of sorbitol

The chronopotentiometric technique was used to analyze the electrodeposition of Fe–Zn film on a Pt electrode. Three different Fe³⁺/Zn²⁺ molar ratios, Fe26.8 wt.%–Zn73.2 wt.%, Fe46 wt.%–Zn54 wt.% and Fe66.6 wt.%–Zn33.4 wt.%, were used in a solution containing sorbitol as the Fe³⁺-complexing agent, with a total concentration of the two cations of 0.20 M. Coloration of Fe–Zn films were light gray, dull dark gray and bright graphite, depending on the Fe³⁺/Zn²⁺ ratios in the deposition bath. The highest stripping to deposition charge density ratio was 47.5%, at 15 mA cm⁻² in the Fe26.8 wt.%–Zn73.2 wt.% bath. Energy dispersive spectroscopy indicated that the codeposition type of Fe and Zn in the Fe26.8 wt.%–Zn73.2 wt.% and Fe46 wt.%–Zn54 wt.% baths was normal at all j_d tested, while in the Fe66.6 wt.%–Zn33.4 wt.% bath there was a transitional current density from normal to equilibrium codeposition at 50 mA cm⁻². Scanning electron microscopy showed that Fe–Zn films of high quality were obtained from the Fe66.6 wt.%–Zn33.4 wt.% and Fe26.8 wt.%–Zn73.2 wt.% baths, since the films were smooth. X-ray analysis of the Zn–Fe films obtained at 15, 25 and 50 mA cm⁻², in the Fe26.8 wt.%–Zn73.2 wt.%, Fe46 wt.%–Zn54 wt.% and Fe66.6 wt.%–Zn33.4 wt.% plating baths, suggested the occurrence, in general, of a mixture of Fe₁₁Zn₄₀, Fe₄Zn₉, βFe, αFe, Fe₂O₃, Zn and PtZn alloys in the deposit.     

Influence of copper concentration on sprayed CZTS thin films deposited at high temperature

In this study, Cu₂ZnSnS₄ (CZTS) thin films were deposited by spray pyrolysis technique at constant substrate temperature. The effects of the copper concentration on the structural, morphological and optical properties of the films were investigated. The copper concentration was varied from 0.15 to 0.25 M in the steps of 0.05 M. The structural studies revealed that the Cu poor film shows low intense peaks, but as Cu concentration increases a relatively more intense and sharper diffraction peaks (112), (200), (220), and (312) of the kesterite crystal structure were observed. Raman spectroscopy analysis confirmed the formation of phase-pure CZTS films. From the morphological studies, it is found that the grain size increased as the Cu concentration increases from 0.15 to 0.25 M. The optical band-gap values were estimated to be 1.61, 1.52 and 1.45 eV for copper concentration 0.15, 0.20 and 0.25 M, respectively. Photoelectrochemical cells using films of different copper concentrations were fabricated and the best cell exhibited an efficiency of 1.09% for 0.25 M of copper concentration.     

Studies on chemical bath deposited SnS2 films for Cd-free thin film solar cells

Tin disulfide (SnS₂) is a simple binary metal chalcogenide and it has been proposed as a promising buffer material for Cd-free thin film solar cells. The present work explores the deposition of SnS₂ films by a facile chemical bath deposition at different deposition times in the range of 30–120 min. The effect of deposition time on the structural, optical and electrical properties was investigated. The as-grown SnS₂ films showed a hexagonal crystal structure with a high intensity (001) peak at 15.03°. The films showed shuttle shaped grains that were uniformly distributed across the surface of the substrate. The films showed an optical energy band gap in the range of 2.95–2.80 eV. PL spectra showed a strong emission peak in the wavelength range, 410–460 nm with the variation of deposition time. The SnS₂ films prepared at a deposition time of 90 min showed good crystallinity and morphology with low resistivity of 11.2 Ω-cm. A solar cell with device structure of Mo/SnS/SnS₂/i-ZnO/Al: ZnO/Ni/Ag was fabricated. The fabricated solar cell showed an efficiency of 0.91%, which validate the photovoltaic performance of SnS₂ films.     

Ferroelectric properties of pure ZrO2 thin films by chemical solution deposition

Ferroelectricity in pure zirconia (ZrO₂) thin films, manufactured on Si (100) substrates via the chemical solution deposition method using all-inorganic aqueous salt precursor, has been demonstrated for the first time. The influence of thickness on the crystalline structure and ferroelectric properties of the thin films were measured and showed that they were strongly affected by the film thickness. The structural data indicated that as the film thickness increased from 30 nm to 50 nm, the m-phase fraction increased, and a phase transition from orthorhombic to cubic and then tetragonal occurred near the main diffraction peak of 30.7°. The lowest m-phase fraction of 15.4% was obtained in the pure ZrO₂ film with a thickness of 30 nm, and after 10³ field cycling, it exhibited the highest relative permittivity of 39.6 as well as the highest residual polarization of 8.5 μC/cm².     

Effect of excess Bi2O3 on structures and dielectric properties of Bi1.5Zn1.0Nb1.5O7 thin films deposited at room temperature by RF magnetron sputtering

To compensate for bismuth loss that occurred during the film deposition process, Bi_1.5Zn_1.0Nb_1.5O₇ (BZN) thin films were deposited at room temperature from the ceramic targets containing various excess amounts of bismuth (0–20 mol%) on Pt/TiO₂/SiO₂/Si substrates by using RF magnetron sputtering technique. The effect of bismuth excess content on the microstructure and electrical properties of BZN thin films was studied. The microstructure and chemical states of the thin films were studied by SEM and XPS. EPMA was employed to assess the film stoichiometry. The X-ray diffraction analysis reveals that the BZN thin films exhibit the amorphous structure in nature. An appropriate amount of excess bismuth improves the dielectric and electrical properties of BZN thin films, while too much excess bismuth leads to deterioration of the properties. BZN thin film with 5 mol% excess bismuth exhibits a dielectric constant of 61 with a loss of 0.4% at 10 kHz and leakage current of 7.26×10^?7 A/cm² at an electric field of 200 kV/cm.     

Enhanced optoelectronic properties of Ti-doped ZnO nanorods for photodetector applications

We report the effect of Ti-doping on structural, morphological, photoluminescence, optical and photoconductive properties of ZnO thin films. Pure and Ti(1, 3 and 5%)-doped ZnO thin films are deposited by the successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction analysis revealed the single-phase hexagonal wurtzite ZnO structure of all the films. Scanning electron microscope images suggest the formation of rod shaped particles in Ti-doped ZnO thin films. Photoluminescence spectra of all the films show emission peaks centered at 398 nm, 413 nm, 438 nm, 477 nm and 522 nm wavelengths. Optical properties support the semiconducting nature of all the films. The optical bandgap values are estimated to be 3.29 eV, 3.26 eV, 3.19 eV and 3.23 eV for ZnO, ZnO:Ti(1%), ZnO:Ti(3%) and ZnO:Ti(5%) thin films, respectively. Photoconductivity study indicates that ZnO:Ti(3%) thin film exhibits high responsivity, external quantum efficiency and detectivity of 0.30 AW^-1, 97% and 5.49 × 10¹⁰ Jones, respectively, among all the films. The enhanced photoconductivity of Ti-doped ZnO thin films make them useful for optoelectronic applications.     

Influence of post-annealing atmosphere on microstructure,optical and electrical properties of zinc cadmium oxide films deposited by DC and RF magnetron co-sputtering

Zinc cadmium oxide (Zn_1−xCd_xO) films were deposited on quartz substrates by direct current (DC) and radio frequency (RF) reactive magnetron co-sputtering and the influence of post-annealing atmosphere on their microstructure, optical and electrical properties were investigated by X-ray diffraction (XRD), optical absorbance, photoluminescence (PL) and Hall measurements. Results indicate that the band gap (E_g) of all Zn_1−xCd_xO films annealed in different atmospheres are smaller than that of the undoped ZnO, the observed shifts in E_g being 0.43, 0.37 and 0.32 eV for the Zn_1−xCd_xO films annealed in argon, oxygen and vacuum, respectively. Hall measurement results indicate that all Zn_1−xCd_xO films annealed in different atmospheres show the n-type conduction, but the Zn_1−xCd_xO film annealed in vacuum has low resistivity and high concentration, which has room-temperature resistivity of 1.59 Ω cm and carrier concentration of 2.07×10¹⁷ cm⁻³. Compared with Zn_1−xCd_xO films annealed in oxygen and argon, Zn_1−xCd_xO film annealed in vacuum has the best crystal quality, luminescence and electrical properties. The influencing mechanism of the post-annealing atmosphere on the electrical and optical properties of the Zn_1−xCd_xO film is discussed.