Effects of discharge power on the structural and optical properties of TGZO thin films prepared by RF magnetron sputtering technique

The transparent semiconductors of Ti and Ga-incorporated ZnO (TGZO) thin films were prepared by radio frequency (RF) magnetron sputtering onto glass substrates. The effects of discharge power on the physical properties of thin films are studied. Experimental results show that all nanocrystalline TGZO thin films possess preferential orientation along the (002) plane. The discharge power significantly affects the crystal structure and optical properties of thin films. When the discharge power is 200 W, the TGZO thin film has the optimal crystalline quality and optical properties, with the narrowest full width at half-maximum (FWHM) of 1.76´10-3 rad, the largest average grain size of 82.4 nm and the highest average transmittance of 84.3% in the visible range. The optical gaps of thin films are estimated by the Tauc’s relation and observed to increase firstly and then decrease with the increase of the discharge power. In addition, the optical parameters, including refractive index, extinction coefficient, dielectric function and dissipation factor of the thin films, are determined by optical characterization methods. The dispersion behavior of the refractive index is also analyzed using the Sellmeier’s dispersion model.     

Study on the structural, electrical and optical properties of Al-F co-doped ZnO thin films prepared by RF magnetron sputtering

Al and F co-doped ZnO(ZnO:(Al,F)) thin films on glass substrates are prepared by the RF magnetron sputtering with different F doping contents.The structural,electrical and optical properties of the deposited films are sensitive to the F doping content.The X-ray analysis shows that the films are c-axis orientated along the(002) plane with the grain size ranging from 9 nm to 13 nm.Micrographs obtained by the scanning electron microscope(SEM) show a uniform surface.The best films obtained have a resistivity of 2.16×10-3Ω·cm,while the high optical transmission is 92.0% at the F content of 2.46 wt.%.     

Research on the properties of ZnO1-xSx thin films modified by sulfur doping for CIGS solar cells

ZnO1-xSx thin films modified by sulfur doping were prepared on glass substrates by chemical bath deposition (CBD) for studying the effect of thiourea concentration on the thin film properties. The obtained ZnO1-xSx thin films were characterized by scanning electron microscopy (SEM), which shows the surfaces of ZnO1-xSx thin films deposited under the thiourea concentration of 0.14 M are more compact. X-ray diffraction (XRD) measurement shows that the ZnO1-xSx thin films with hexagonal crystal structure had strong diffraction peaks and better crystallinity. The optical transmittance of the ZnO1-xSx thin films with 0.14 M thiourea concentration is above 80% in the wavelength range of 300—900 nm. According to the measurement results from spectrophotometer, the ZnO1-xSx band gap energy value Eg varies nonlinearly with different S/(S+O) ratio x, and increases with the increase of x. There is a band gap value of 2.97 eV in the ZnO1-xSx thin films deposited under 0.14 M thiourea concentration. Therefore, the thin films have better structural, optical and electric properties, and are more suitable for the buffer layers of copper indium gallium selenide (CIGS) thin film solar cells.     

The calculation of band gap energy in zinc oxide films

We investigated the optical properties of undoped zinc oxide thin films as the n-type semiconductor; the thin films were deposited at different precursor molarities by ultrasonic spray and spray pyrolysis techniques. The thin films were deposited at different substrate temperatures ranging between 200 and 500 ℃. In this paper, we present a new approach to control the optical gap energy of ZnO thin films by concentration of the ZnO solution and substrate temperatures in a cost-effective way. The model proposed to calculate the band gap energy with the Urbach energy was investigated. The relation between the experimental data and theoretical calculation suggests that the band gap energies are predominantly estimated by the Urbach energies, film transparency, and concentration of the ZnO solution and substrate temperatures. The measurements by these proposal models are in qualitative agreements with the experimental data; the correlation coefficient values were varied in the range 0.96-0.99999, indicating high quality representation of data based on Equation (2), so that the relative errors of all calculation are smaller than 4%. Thus, one can suppose that the undoped ZnO thin films are chemically purer and have many fewer defects and less disorder owing to an almost complete chemical decomposition and contained higher optical band gap energy.     

Structural and opto-electrical properties of pyrolized ZnO-CdO crystalline thin films

A series of ZnO-CdO thin films of different molar ratios of Zn and Cd have been deposited on glass substrate at substrate temperature ~ 360 ℃ by the spray pyrolysis technique at an ambient atmosphere. X-ray diffraction (XRD) studies confirmed the polycrystalline nature of the film and modulated crystal structures of wurtzite (ZnO) and cubic (CdO) are formed. The evaluated lattice parameters, and crystallite size are consistent with literature. Dislocation density and strain increased in the film as the grain sizes of ZnO and CdO are decreased. The band gap energy varies from 3.20 to 2.21 eV depending on the Zn/Cd ratios in the film. An incident photon intensity dependent I-V study confirmed that the films are highly photosensitive. Current increased with the increase of the intensity of the light beam. The optical conductivity and the optical constants, such as extinction coefficient, refractive index and complex dielectric constants are evaluated from transmittance and reflectance spectra of the films and these parameters are found to be sensitive to photon energy and displayed intermediate optical properties between ZnO and CdO, making it preferable for applications as the buffer and window layers in solar cells.     

Recent Advances in ZnO Films Prepared by Pulsed Laser Deposition

Pulsed laser deposition （PLD） is emerging as the most rapid and efficient technique for fabricating the many compound films. ZnO thin films can be prepared under various deposition conditions by PLD. The effects of various substrate temperature, oxygen partial pressure, annealing temperature, substrate, buffer layers thickness and film thickness on micro-structural, optical and electrical properties of ZnO films grown by PLD technology are reviewed. ZnO films with special function can grow under proper conditions by PLD.     

利用磁控溅射在GaN/蓝宝石衬底上生长ZnO薄膜

Zinc oxide (ZnO) thin films were grown on n-GaN/sapphire substrates by radio-frequency (RF) magnetron sputtering. The films were grown at substrate temperatures ranging from 400 to 700 ℃ for 1 h at a RF power of 80 W in pure Ar gas ambient. The effect of the substrate temperature on the structural and optical properties of these films was investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence (PL) spectra. XRD results indicated that ZnO films exhibited wurtzite symmetry and c-axis orientation when grown epitaxially on n-GaN/sapphire. The best crystalline quality of the ZnO film is obtained at a growth temperature of 600 ℃. AFM results indicate that the growth mode and degree of epitaxy strongly depend on the substrate temperature. In PL measurement, the intensity of ultraviolet emission increased initially with the rise of the substrate temperature, and then decreased with the temperature. The highest UV intensity is obtained for the film grown at 600 ℃ with best crystallization. oindent     

Electrical properties of silver Schottky contacts to ZnO thin films

ZnO thin films are deposited on Al/Si substrates by the pulsed laser deposition （PLD） method. The XRD and SEM images of films are examined. Highly c-axis oriented ZnO thin films which have uniform compact surface morphology are fabricated. The size of surface grains is about 30 nm. The Schottky barrier ultraviolet detectors with silver Schottky contacts are made on ZnO thin films. The current-voltage characteristics are measured. The ideality contact factor between Ag and ZnO film is 1.22, while the barrier height is 0.908 e V. After annealing at 600 ℃ for 2h, the ideality factor is 1.18 and the barrier height is 0.988 eV. With the illumination of 325 nm wavelength UV-light, the photocurrent-to-dark current ratios before and after annealing are 140.4 and 138.4 biased at 5 V, respectively. The photocurrents increase more than two orders of magnitude over the dark currents.     

Effects of the ZnO buffer layer and Al proportion on AZO film properties

To evaluate the influence of the ZnO buffer layer and Al proportion on the properties of ZnO: Al (AZO)/ZnO bi-layer films, a series of AZO/ZnO films are deposited on the quartz substrates by electron beam evaporation. The X-ray diffraction measurement shows that the crystal quality of the films is improved with the increase of the film thickness. The electrical properties of the films are investigated. The carrier concentration and Hall mobility both increase with the increase of buffer layer thickness. However, the resistivity reaches the lowest at about 50 nm-thick buffer layer. The lowest resistivity and the maximum Hall mobility are both obtained at 1 wt% Al concentration. But the optical transmittance of all the films is greater than 80% regardless of the buffer layer thickness with Al concentration lower than 5 wt% in the visible region.     

Polycrystalline ZnO Films Deposited on Glass by RF Reactive Sputtering

Polycrystalline ZnO films were prepared on glass wafer using Zn targets by radio frequency(RF)reactive sputtering technique under different deposition conditions.X-ray diffraction (XRD) and optical transmittance spectrum were employed to analyze the structure and optical character of the films.The strain and stress in films, as well as the packing density are calculated in terms of refractive index of films measured with an elliptic polarization analyzer.It is the deposition conditions that have great effects on the structural and optical properties of ZnO films.Under the optimal conditions,the only evident peak in XRD spectrum was (002) peak with the full width at half maximum (FWHM) of 0.20° showing the grain size of 42.8 nm.The packing density,the stress in (002) plane and the average optical transmittance in the visible region were about 97%,-1.06×10~9 N/m~2 and 92%, respectively.     

ZnO/Ag/ZnO多层膜的制备和性质研究

采用射频磁控溅射ZnO陶瓷靶和直流磁控溅射Ag靶的方法制备了ZnO/Ag/ZnO多层膜。用X射线衍射仪、紫外–可见分光光度计、四探针测试仪和金相显微镜对ZnO/Ag/ZnO薄膜的结构、光学透过率、方阻和稳定性进行了研究。结果表明,ZnO(60nm)/Ag/(10nm)/ZnO(60nm)薄膜呈现多晶结构,薄膜在520nm处的光学透过率高达87.5%,方阻Rs为6.2Ω/□。随着顶层ZnO薄膜厚度的增加,ZnO/Ag/ZnO薄膜的稳定性提高。     

Ag层的厚度对ZnO/Ag/ZnO多层膜性能的影响

采用射频磁控溅射ZnO陶瓷靶、直流磁控溅射Ag靶的方法制备了不同厚度Ag夹层的ZnO(60nm)/Ag/ZnO(60nm)多层膜.分别用X射线衍射仪、紫外可见分光光度计、四探针测试仪对样品的结构、光学性质、电学性质进行了研究.结果表明:随着Ag层厚度的增加,ZnO/Ag/ZnO多层膜呈现多晶结构,Ag(111)衍射峰的强度增强.Ag夹层厚度为11nm时,ZnO(60nm)/Ag/ZnO(60nm)膜在554nm处的透过率高达92.3%.随着Ag层厚度的增加,Ag膜的特征吸收峰呈现红移和宽化,ZnO/Ag/ZnO多层膜的面电阻先减小后趋于稳定.     

室温下制备的ZnO/Ag/ZnO多层膜的性能

采用射频磁控溅射ZnO陶瓷靶、直流磁控溅射Ag靶的方法在室温下制备了不同厚度的ZnO/Ag/ZnO多层膜。对样品进行了研究。结果表明:随着Ag层厚度的增加,ZnO(002)衍射峰的强度先增加后减小,Ag(111)衍射峰的强度增强,ZnO/Ag/ZnO多层膜的面电阻先减小后趋于稳定。ZnO膜厚度增加,Ag膜易形成晶状结构,ZnO/Ag/ZnO多层膜的透射峰向长波方向移动。ZnO(60nm)/Ag(11nm)/ZnO(60nm)膜在554nm处的透过率高达92.3%,面电阻为4.2?/□,品质常数?TC最佳,约40×10–3/?。     

制备工艺对ZnO薄膜的结构与光学性质的影响

利用射频磁控反应溅射技术生长出具有高度晶面(0002)取向的ZnO外延薄膜。通过AFM、XRD、吸收光谱和荧光光谱等测试手段,分别研究分析了不同衬底、不同溅射气氛和退火对ZnO薄膜结构及光学性质的影响。研究表明,在200℃低温生长的硅基ZnO薄膜具有几百纳米的氧化锌准六角结构外形;当氧氩比为4:1(质量流量比)时,吸收谱激子峰最佳;退火后,激子峰(363 nm)加强,同时出现了402 nm的本征氧空位紫光发射。     

玻璃和聚酰亚胺衬底上磁控溅射沉积的ZnO:Al透明导电膜的结构、电学和光学性能(英文)

利用射频磁控溅射方法在玻璃和聚酰亚胺膜(PI)衬底上沉积了氧化铝质量分数为2%的掺铝氧化锌透明导电薄膜(ZnO∶Al)。系统地研究了不同衬底材料对薄膜的结构、电学以及光学性能的影响。分析表明,衬底材料对薄膜的结晶性和电学性能有较大的影响,对可见光透射率却影响不大。X射线衍射(XRD)分析得出所有的ZnO∶Al具有良好的c轴择优取向性,在可见光区(400～800nm)两种衬底上的薄膜都达到了85%的透射率。玻璃衬底上的薄膜呈现出更强的(002)衍射峰及相对更小的半峰全宽(FWHM),薄膜电阻率达到了2.352×10-4Ω.cm。电镜分析表明,相对于PI上的ZnO∶Al膜,玻璃上ZnO∶Al膜表面有更致密的微观结构及更大的晶粒尺寸。PI衬底上的ZnO∶Al膜也有相对较好的电、光学性能,其中电阻率达到了6.336×10-4Ω.cm,而且由于PI衬底柔性可弯曲,使得它适于在柔性太阳电池和柔性液晶显示中做窗口层材料及透明导电电极。玻璃上的ZnO∶Al膜则可应用在平板显示和太阳电池技术中。     

无机络合溶胶-凝胶法制备多孔ZnO薄膜

利用无机络合溶胶-凝胶法制备多孔ZnO薄膜,同时利用多种测试手段对薄膜的晶体结构、表面形貌、多孔和光学性能进行了研究.XRD和SEM的测试结果表明,ZnO薄膜的晶体结构为六方纤锌矿,薄膜表面呈多孔状.由孔径分布曲线得出薄膜的孔主要集中在介孔2.02nm和4.97nm;500℃煅烧得到的ZnO薄膜的比表面积是27.57m2/g;在不同温度下煅烧的薄膜在可见光区域透射率均高于85%,光学带宽为3.25eV.     

溅射ZnO薄膜钝化GaAs表面性能的研究

为了改善GaAs(110)与自身 氧化物界面由于高表面态密度而引起的费米能级钉扎(pinning)问题 ,提出采用射频磁控溅射技 术在GaAs(110)衬底上沉积一定厚度 ZnO薄膜作为钝化层,并利用光 致发光(PL)光谱和X射线光电子能谱(XPS) 等方法对ZnO薄膜的光学特性及钝化性能进行表征。实验结果表明,经ZnO薄膜钝化后的 GaAs样品,其本征PL峰强度提高112.5%,杂质峰强度下降82.4%。XPS光谱分析表明,Ga和As原子的比值从1.47降低 到0.94,ZnO钝化层能 够抑制Ga和As的氧化物形成。因此,在GaAs表面沉积ZnO薄膜是一种可行的GaAs表面钝化 方法。     

Al薄膜对(002)ZnO/Al/Si结构基片中ZnO薄膜特性影响的实验研究

采用射频磁控溅射法沉积制备了(002)ZnO/A l/Si复合结构。研究了Al薄膜对(002) ZnO/Al/Si复合结构的声表面波器件(SAWD)基片性能影响以及当ZnO 薄膜厚度一定时的Al膜最佳厚度。采用X射线衍射(XRD)对Al和ZnO薄膜进行了结构表征 ,采用 扫描电镜(SEM)对ZnO薄膜进行表面形貌表征,并从薄膜生长机理角度进行了分析。结果 表明,加Al薄膜有利于ZnO薄膜按(002)择优取向生长,并且ZnO 薄膜的结晶性能提高;与(002)ZnO/Si结构基片相比,当Al薄膜 厚为100nm时,(002)ZnO/Al/Si结构中ZnO薄 膜的机电耦合系数提高 了65%。     

Surface planarization of ZnO thin film for optoelectronic applications

In this paper, surface morphology and optical properties are investigated to find the optimum microstructure of zinc oxide (ZnO) thin films deposited by radio frequency (RF) magnetron sputtering. To achieve a high transmittance and a low resistivity, we examined various film deposition conditions. The transmittance and surface morphology of ZnO thin films were measured by an ultraviolet (UV)-visible spectrometer and atomic force microscopy (AFM), respectively. In order to improve the surface quality of ZnO thin films, we performed chemical mechanical polishing (CMP) by change of process parameters, and compared the optical properties of polished ZnO thin films. As an experimental result, we were able to obtain good uniformity and improved transmittance efficiency by the CMP technique.     

表面等离子体共振增强ZnO/Ag薄膜发光特性研究

为了提高氧化锌光致发光强度,以磁控溅射氧化锌/银复合薄膜为研究对象,系统地研究了氧化锌薄膜的光学性质。实验中首先在硅衬底上用射频磁控溅射的方法沉积氧化锌/银复合薄膜,作为对比,同时沉积了一层氧化锌薄膜。通过扫描电子显微镜和原子力显微镜对样品的形貌及成份进行表征,并且在室温下测试样品在300~800 nm波长范围内的光致发光光谱。实验结果表明:所制得样品为均匀分布的氧化锌纳米薄膜,纯氧化锌光致发光光谱结果显示有波长位于378 nm左右的紫光、470 nm左右的蓝色发光峰存在,加入银薄膜后,氧化锌可见光区和紫外光区的光致发光光谱强度均有所增强,而且紫外光峰位出现了红移。实验结果结合样品吸收谱对光致发光机理的分析作了进一步的分析。