射频反应磁控溅射法制备ZnO:Al透明导电薄膜的光电性能

室温下采用射频(RF)反应磁控溅射技术在玻璃衬底上沉积具有(002)择优取向的透明导电Al掺杂ZnO(AZO)薄膜。XRD结果表明,制备的AZO薄膜为多晶,具有c轴择优取向。退火处理能提高其结晶度。在Al靶射频功率为40W,ZnO靶射频功率为250W,氩气流量为15mL/min的条件下,获得200nm厚的薄膜电阻率约3.8×10-3?·cm,在可见光范围内有很好的光透过率。     

Room temperature deposition of Al-doped ZnO thin films on glass by RF magnetron sputtering under different Ar gas pressure

Al-doped ZnO (AZO) thin films were deposited on glass substrates at room temperature by RF magnetron sputtering. The effects of Ar gas pressure on the structural, optical, and electrical properties were investigated. As the Ar gas pressure increased, the resistivities of the AZO thin films increased, the mobilities decreased, and the carrier concentrations were constant. X-ray photoelectron spectroscopy (XPS) showed that higher Ar gas pressures promoted O-Zn bond formation and reduced the number of oxygen vacancies. The reduction in mobility, which increased the resistivity, was attributed to increased lattice scattering by the oxygen atoms. In AZO thin films deposited at room temperature, the conduction characteristics are primarily influenced by the mobility.     

溅射气压对ZnO透明导电薄膜光电性能的影响

采用射频磁控溅射方法,在普通玻璃上制备了具有高度c轴取向的ZnO薄膜,研究了溅射气压(0.2～1.5 Pa)对ZnO薄膜的微观结构和光电性能的影响.AFM、XRD、UV-Vis分光光度计及四探针法研究表明:随着溅射气压的增大,ZnO薄膜沿c轴方向的结晶质量提高,晶粒细化,薄膜表面更加致密,晶粒大小更加均匀;ZnO薄膜在400～900nm范围内的平均透过率均高于85%,其中在0.5～1.5 Pa范围内其透过率高于90%;样品在高纯氮气气氛中经350 ℃,300 s退火后,电阻率最低达到10-2 Ω-cm量级.     

Variations in electrical and physical properties of Al:ZnO films with preparation conditions

This study examined the effects of the RF magnetron sputtering power and substrate temperature on the electrical and physical properties of Al:ZnO (AZO) thin films deposited on GaAs(011) and Si(001) substrates. The stress on the films, which was estimated by determining the position of the (002) XRD diffraction peaks, varied from 5.28 GPa to 2.29 GPa for the films deposited between 100 and 250 W RF power. A similar trend was observed for the films prepared at substrate temperatures ranging from R.T. to 300 °C. The films prepared at 100 °C showed the least amount of stress and the largest concentration of charge carriers. The concentration of charge carriers produced from the presence of [Al_Zn] is closely related to the stress on the films. Post-deposition annealing in a reducing atmosphere had not only decreased the compressive stress, but had also formed oxygen vacancies. The increased concentration of charge carriers after annealing was attributed to the ionization of oxygen vacancies with a probability of 0.1±0.03.     

透明导电氧化物ZnO:Al(ZAO)薄膜的研究

用磁控反应溅射法制备了ＺｎＯ：Ａｌ薄膜,研究了薄膜方块电阻空间分布的均匀性及微观形貌,并对ＺｎＯ：Ａｌ薄膜表面各元素的化学状态和深度分布进行了ＸＰＳ和ＡＥＳ分析,同时也讨论了薄膜的光学电学性能。     

Influence of oxygen gas content on the structural and optical properties of ZnO thin films deposited by RF magnetron sputtering at room temperature

Zinc oxide (ZnO) thin films were deposited on sapphire (0001) substrates at room temperature by radiofrequency (RF) magnetron sputtering at oxygen gas contents of 0%,25%,50% and 75%,respectively.The influence of oxygen gas content on the structural and optical properties of ZnO thin films was studied by a surface profile measuring system,X-ray diffraction analysis,atomic force microscopy,and UV spectrophotometry.It is found that the size of ZnO crystalline grains increases first and then decreases with the increase of oxygen gas content,and the maximum grain size locates at the 25% oxygen gas content.The crystalline quality and average optical transmittance (>90%) in the visible-light region of the ZnO film prepared at an oxygen gas content of 25% are better than those of ZnO films at the other contents.The obtained results can be attributed to the resputtering by energetic oxygen anions in the growing process.     

Zn靶与掺铝ZnO靶共溅射制备ZnO:Al薄膜及其性能

采用Zn靶和ZnO(掺2%Al2O3(质量分数))陶瓷靶在玻璃衬底上共溅射沉积Al掺杂ZnO薄膜,即ZnO:Al透明导电薄膜,研究Zn靶溅射功率(0～90 W)和衬底温度(室温、100℃和200℃)对薄膜结构、形貌、光学和电学性能的影响。结果表明:按双靶共溅射工艺制备的ZnO:Al薄膜的晶体结构均为六角纤锌矿结构,且随着Zn靶溅射功率的增加,薄膜的结晶质量呈现出先改善后变差的规律,薄膜中的载流子浓度逐渐升高,电阻率逐渐降低,而薄膜的光学性能受其影响不大;随着衬底温度的升高,薄膜的结晶性能得到改善,薄膜的可见光透过率增强,电阻率降低。     

Effect of annealing treatment onoptical and electrical properties of ZnO films

The ZnO-Al films were prepared by R. F. magnetron sputtering system using a Zn-Al target (with purity of 99.99 %). The obtained films were characterized by X-ray diffraction, SEM and optical and electrical measurements. The experimental results show that the properties of ZnO films can be further improved by annealing treatment. The crystallinity of ZnO films becomes better, and the optical gap energy is decreased, but thermoelectric power is enhanced after heat treatment. The optical gap energy decreases from 3.75 eV to 3.68 eV when the annealing temperature increases from 25℃ to 400℃. This can be ascribed to the decrease of carrier concentration, resulting in Burstein shift.     

Characteristics of atomic layer deposited transparent aluminum-doped zinc oxide thin films at low temperature

Various aluminum-doped zinc oxide(AZO) films were prepared on Si substrate by atomic layer deposition(ALD) at 100℃. The effect of the composition of AZO films on their electrical, optical characteristics,structural property and surface topography was investigated. The appearance of electrical resistivity shows their semiconducting properties. In most of the visible light band, all the AZO films present transparency of more than 80%. Al doping suppresses the AZO film crystallization.When the Al doping concentration increases up to 3.95 at%, the AZO film has some small multicrystal grains with random orientation. Al doping improves the roughness of i-ZnO film. The root mean square(RMS) roughness of samples prepared by ALD is much smaller than that prepared by radio-frequency magnetron sputtering reported.     

Preparation and Properties Of ZnO:Al (ZAO) Thin Films Eposited by DC Reactive Magnetron Sputtering

采用磁控溅射技术制备了ZnO:Al(ZAO)薄膜。研究了不同的工艺参数对薄膜的组织结构和光电特性的影响.实验结果表明，多晶ZAO薄膜具有（001）择优取向且呈柱状生长，能量机制决定其微观生长状态。讨论了薄膜的内应力，高的沉积温度和低的溅射功率可有效减小薄膜的内应力。优化的ZAO薄膜电阻率和在可见光区的平均透射率可分别达到310-4-410-4cm和80%以上。     

A comparison of transmittance properties between ZnO∶Al films for transparent conductors for solar cells deposited by sputtering of AZO and cosputtering of AZO/ZnO

Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) andglass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target. The dependence of the photoluminescence (PL) and transmittance properties of the AZO films deposited by cosputtering and sputtering on the AZO/ZnO target power ratio, R and the O2/Ar flow ratio, r were investigated, respectively. Only a deep level emission peak appears in the PL spectra of cosputtered AZO films whereas both UV emission and deep level emission peaks are observed in the PL spectra of sputtered AZO films. The absorption edges in the transmittance spectra of the AZO films shift to the lower wavelength region as R and r increase. Effects ofcrystallinity, surface roughness, PL on the transmittance of the AZO films werealso explained using the X-ray diffraction (XRD), atomic force microscopy (AFM), and PL analysis results.     

氩气压力对中频磁控溅射制备AZO薄膜性能的影响

在普通玻璃衬底上利用掺杂2%(质量)Al2O3的ZnO陶瓷靶材在中频磁控溅射设备中制备了掺铝氧化锌(ZnO∶Al,AZO)薄膜.利用XRD、XPS、紫外可见分光光度计和Hall测试系统研究了Ar气压力(0.73～2.0 Pa)对AZO透明导电薄膜结构、光学和电学性能的影响.随着Ar气压力的增大,电阻率呈先减小后增大的趋...     

溅射功率对射频磁控溅射Al掺杂ZnO（ZAO）薄膜性能的影响

用射频磁控溅射技术,在纯氩气氛中不同溅射功率（120 W~210 W）下于玻璃衬底上制备了Al掺杂ZnO（ZAO）薄膜。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、光谱仪和四探针测试仪等对所制备的薄膜进行了晶体结构、光学和电学性能分析。结果表明,纯氩气氛中不同溅射功率下玻璃衬底上原位沉积的ZAO薄膜具有明显的c轴择优取向性,它没有改变ZnO的六角纤锌矿结构;ZAO薄膜的可见光区平均透光率不强烈依赖于溅射功率,为75%左右;原位沉积ZAO薄膜的电阻率达到102Ω.cm数量级范围,随溅射功率由120 W增大到210 W时,薄膜电阻率从132.67Ω.cm降低到21.08Ω.cm。     

沉积和退火温度对多晶ZnO薄膜结构特性的影响

采用RF反应溅射法在Si（111）衬底上制备出了沿C轴高度取向的多晶ZnO薄膜。通过对ZnO薄膜的X射线衍射（XRD）分析,研究了沉积温度及退火对多晶ZnO薄膜取向性、晶粒大小和应力的影响。结果表明,衬底温度和退火温度对多晶ZnO薄膜的晶体结构影响显著。适当的提高衬底温度或适当的增加退火温度都能有效地改善ZnO薄膜的结构特性,但增加退火温度更有优势。同时原子力显微镜观察表明,退火能有效地降低ZnO薄膜的表面粗糙程度。     

Thermal stability of electrical properties of ZnO:Al films deposited by room temperature magnetron sputtering

In order to investigate the thermal stability of electrical properties for aluminum doped zinc oxide (ZnO:Al, AZO) films deposited by direct current reactive magnetron sputtering, AZO films deposited from an alloy target (0.8 wt.% Al) on soda-lime glasses were annealed in argon gas at different temperatures. A data capturer was applied to monitor and collect real-time sheet resistance (R_s) of the films throughout the annealing. Results revealed that R_s of the film heated at 100 °C was reduced throughout the annealing, however, conductivity of the films annealed over 100 °C was improved at early stage but then deteriorated all along to the end. Some novel R_s change points which need more penetrations were detected. The experimental results obtained from electron diffraction spectrum, X-ray diffraction pattern, X-ray photoelectron spectrum, and Hall measurement were analyzed to explore the effect of the annealing on the electrical properties of AZO films. It was found that the exotic element, which might influence the film properties, was not observed. It was also suggested that the transformation of the crystalline structure and surface chemical bonding states, which resulted in the decrease of carrier concentration and mobility could be the reason for the conductivity degeneration of the films annealed at higher temperature.     

Preparation and characterization of ZnO/Cu/ZnO transparent conductive films

ZnO/Cu/ZnO transparent conductive thin films were prepared by RF sputtering deposition of ZnO target and DC sputtering deposition of Cu target on n-type (001) Si and glass substrates at room temperature. The morphology, structure, optical, and electrical properties of the multilayer films were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV/Vis spectrophotometer, and Hall effect measurement system. The influence of Cu layer thickness and the oxygen pressure in sputtering atmosphere on the film properties were studied. ZnO/Cu/ZnO transparent conductive film fabricated in pure Ar atmosphere with 10 nm Cu layer thickness has the best performance: resistivity of 2.3×10-4 Ω·cm, carrier concentration of 6.44×1016cm-2 , mobility of 4.51cm2·(V·s)-1 , and acceptable average transmittance of 80 % in the visible range. The transmittance and conductivity of the films fabricated with oxygen are lower than those of the films fabricated without oxygen, which indicates that oxygen atmosphere does not improve the optical and electrical properties of ZnO/Cu/ ZnO films.     

Effect of sputtering pressure and rapid thermal annealing on optical properties of Ta2O5 thin films

Ta2O5 thin films were deposited by DC reactive magnetron sputtering followed by rapid thermal annealing(RTA). Influence of sputtering pressure and annealing temperature on surface characteristics, microstructure and optical property of Ta2O5 thin films were investigated. As-deposited Ta2O5 thin films are amorphous. It takes hexagonal structure (δ-Ta2O5) after being annealed at 800 ℃. A transition from δ-Ta2O5 to orthorhombic structure (L-Ta2O5) occurs at 900-1 000 ℃. Surface roughness is decreased after annealing at low temperature. Refractive index and extinction coefficient are decreased when annealing temperature is increased.     

Effect of Annealing on the Morphology,Structure and Photoelectric Properties of AZO/Pt/FTO Trilayer Films

Aluminum-doped zinc oxide/platinum/fluorine-doped tin oxide(AZO/Pt/FTO) trilayer films were prepared by sputtering 5-nm-thick Pt layers and 150-nm-thick AZO layers in sequence on commercial FTO glass.The effects of onestep annealing and layer-by-layer annealing on the morphology,structure and photoelectric properties of the AZO/Pt/FTO trilayer films were comparatively analyzed.It is found that the both annealing approaches increased the grain size and improved the crystallinity of the films,leading to enhancement in transmittance and conductivity.However,layer-by-layer annealing led to the formation of quasi-continuous or continuous AZO layers,different from the sparsely distributed AZO particles brought about by one-step annealing,resulting in excellent optical and electrical properties.Specifically,after layer-by-layer annealing at 400 ℃ for both Pt and AZO layers,the AZO/Pt/FTO trilayer film showed an increase in average transmittance from 71.3% to 85.3% and a decrease in sheet resistance from 7.5 to 5.6 Ω/□,leading to the highest figure of merit of 3.64 × 10~(-2) Ω~(-1).     

P-type transparent conducting SnO2:Zn film derived from thermal diffusion of Zn/SnO2/Zn multilayer thin films

Highly transparent, p-type conducting SnO₂:Zn thin films are prepared from the thermal diffusion of a sandwich structure of Zn/SnO₂/Zn multilayer thin films deposited on quartz glass substrate by direct current (DC) and radio frequency (RF) magnetron sputtering using Zn and SnO₂ targets. The deposited films were annealed at various temperatures for thermal diffusion. The effect of annealing temperature and time on the structural, electrical and optical performances of SnO₂:Zn films was studied. XRD results show that all p-type conducting films possessed polycrystalline SnO₂ with tetragonal rutile structure. Hall effect results indicate that the treatment at 400 °C for 6 h was the optimum annealing parameters for p-type SnO₂:Zn films which have relatively high hole concentration and low resistivity of 2.389 × 10¹⁷ cm^− 3 and 7.436 Ω cm, respectively. The average transmission of the p-type SnO₂:Zn films was above 80% in the visible light range.     

退火氛围及温度对掺钛氧化铟薄膜光电性能的影响

利用磁控溅射法在室温下制备了掺钛的氧化铟薄膜,并将薄膜在氮气及真空两种氛围下进行退火。研究了退火氛围及温度对掺钛氧化铟薄膜的光电性能的影响。实验发现,氮气氛围下较低的退火温度能够部分提高薄膜的电学性能,随退火温度升高,薄膜的电学性能反而下降。与氮气氛围相比,真空下退火更有助于提高掺钛氧化铟薄膜的电子迁移率,并且随退火温度升高,电子迁移率逐渐升高并达到一个稳定值。真空退火处理后,掺钛氧化铟在可见光区域的透光率接近80%,在大于1100nm的长波谱区的透光率也有所增高,并且方块电阻降为10/□,适合作为太阳能电池的窗口材料。