磁控溅射有机聚合物衬底ZnO:Al透明导电膜的结构及光电性能研究

采用射频磁控溅射法在有机薄聚合物膜衬底上制备出铝掺杂的氧化锌 (ZnO :Al)透明导电膜 ,对薄膜的低温制备 (2 5～ 180℃ )、结构和光电特性进行了研究。制备薄膜为多晶膜 ,具有纯氧化锌的纤锌矿结构和 (0 0 2 )择优取向。制备薄膜在可见光区透过率达到 74 % ,最低电阻率为 8.5× 10 -4Ω·cm。     

射频磁控溅射制备的柔性衬底ZnO:Al透明导电薄膜的研究

用射频磁控溅射方法在有机柔性衬底上制备出附着性好、电阻率、透射率高的ＺｎＯ：Ａｌ透明导电膜。研究了薄膜的结构、电学和光学特性。     

射频磁控溅射制备的柔性衬底ZnO∶Al透明导电薄膜的研究

用射频磁控溅射方法在有机柔性衬底上制备出附着性好、电阻率低、透射率高的ＺｎＯ：Ａｌ透明导电膜。研究了薄膜的结构、电学和光学特性     

衬底材料对μc-Si:H薄膜结构特性的影响

对在不锈钢和玻璃衬底上沉积的μc-Si：H薄膜进行了拉曼光谱和扫描电子显微(SEM)分析。拉曼分析显示在相同的工艺参数下,玻璃衬底上沉积的μc-Si：H薄膜的晶化率高于不锈钢衬底上沉积的薄膜,这可能是由于衬底与等离子体之间的电势差不同和衬底表面形貌两方面所致。SEM观察表明玻璃衬底上沉积的μc-Si：H薄膜由尺寸介于200～100nm的团簇构成。     

磁控溅射制备柔性衬底ZnO:Ga透明导电膜微结构及性能研究

室温条件下,采用磁控溅射法在有机柔性衬底聚酰亚胺(PI)表面制备出ZnO:Ga透明导电膜,XRD表明ZnO:Ga薄膜为六角纤锌矿结构的多晶薄膜。研究了溅射功率、氩气分压、溅射时间及衬底负偏压等溅射工艺参数对薄膜结构及光电性能的影响,得出最佳溅射参数分别为:功率100W,氩气分压0.1Pa,溅射时间60min,衬底负偏压40V。结果表明:磁控溅射制备的ZnO:Ga膜附着性良好,电阻率为9.4×10~(-4)Ω·cm,可见光透过率为78%。     

H2流量对直流磁控溅射低温沉积ZnO:Al薄膜结构与性能的影响

在Ar和H2的混合气氛下采用直流磁控溅射在玻璃衬底上低温沉积Al掺杂ZnO,即ZnO∶Al透明导电薄膜,研究H2流量(0～10sccm)对薄膜结构、形貌、光学和电学性能的影响。结果表明:不同H2流量下制备的ZnO∶Al薄膜均为高度C轴取向的六角纤锌矿结构,溅射过程中通入适量的H2能改善ZnO∶Al薄膜的结晶质量和表面形貌;所有薄膜在400～900nm范围内的平均透过率均高于85%;随着H2流量的增大,薄膜的载流子浓度升高,电阻率减小,达到10-4Ω.cm数量级。     

透明导电ZnO:Al(ZAO)薄膜的结构及光电特性研究

ZAO薄膜是一种n型氧化物半导体材料,由于其大的载流子浓度和光学禁带宽度而表现出优良的光电特性。本实验采用射频磁控溅射工艺在无机玻璃衬底上制备ZAO薄膜,靶材为ZAO(3wt%Al2O3)陶瓷靶。系统研究了各工艺参数,如工作气压、射频功率、衬底温度和热处理条件对其结构和光电特性的影响。X射线衍射谱表明ZAO薄膜的(002)衍射峰的位置与纯ZnO晶体相比向低角度方向移动,薄膜中各晶粒具有六角纤锌矿晶体结构且呈c轴择优取向。原位制备的ZAO薄膜经热处理后电阻率降至7 5×10-4Ω·cm,可见光透过率在85%以上。     

玻璃衬底和硅衬底沉积TZO透明导电薄膜的对比研究

利用直流磁控溅射法在室温水冷玻璃衬底和硅片衬底上制备出掺钛氧化锌(ZnO∶Ti)透明导电薄膜。SEM和XRD研究结果表明,两种衬底上的ZnO∶Ti薄膜均为为六角纤锌矿结构的多晶薄膜,且具有c轴择优取向。讨论了衬底对掺钛氧化锌透明导电薄膜光学、电学性能的影响。当玻璃衬底薄膜厚度为568nm时,薄膜电阻率达到最小值1.64×10-4Ω.cm,硅衬底上薄膜厚度为641nm时有最小电阻率2.69×10-4Ω.cm。两种衬底所制备薄膜都具有良好的附着性能,玻璃衬底薄膜样品在波长为500~800nm的可见光中平均透过率都超过了91%,硅衬底上薄膜样品的折射率约为2.05,ZnO∶Ti薄膜可以用作薄膜太阳电池的透明电极。     

ZnO:Al绒面透明导电薄膜的制备及分析

利用中频脉冲磁控溅射方法,采用Al掺杂(质量百分比2%)的Zn(纯度99.99%)金属材料为靶材制备平面透明导电ZnO:Al(ZAO)薄膜。利用湿法腐蚀方法,将平面ZAO薄膜在0.5%的稀盐酸中浸泡一定时间后,形成表面凹凸起伏的绒面结构。研究了平面ZAO薄膜的结构特性以及衬底温度、溅射功率和腐蚀时间对绒面ZAO薄膜表面形貌的影响,并对腐蚀前后薄膜的电阻变化进行了分析。结果表明:高温、低功率条件下制备的绒面ZAO薄膜表面形貌较好,在硅薄膜太阳电池中具有潜在的应用前景。     

有机薄膜衬底ITO透明导电膜的制备及光电特性的研究

采用真空反应蒸发技术，在有机薄膜基片上制备出高质量的ＩＴＯ透明导电薄膜，对薄膜的结构和光电特性进行了研究。制备的最佳薄膜在可见光范围的平均透过率达８４％，电阻率为８．２３×１０－４Ωｃｍ，载流子浓度为１．７２×１０２０ｃｍ－３。     

Structural and optical properties of textured ZnO:Al films on glass substrates prepared by in-line rf magnetron sputtering

Textured ZnO:Al films with excellent light scattering properties as a front electrode of silicon thin film solar cells were prepared on glass substrates by an in-line rf magnetron sputtering, followed by a wet-etching process to modify the surface morphologies of the films. Deposition parameters and wet etching conditions of the films were controlled precisely to obtain the optimized surface features. All as-deposited films show a strong preferred orientation in the [0 0 1] direction under our experimental conditions. The microstructure of the films was significantly affected by working pressure and film compactness was reduced with increasing working pressure, while the effect of a substrate temperature on the microstructure is less pronounced. A low resistivity of 4.25×10⁻⁴ Ω cm and high optical transmittance of above 80% in a visible range were obtained in the films deposited at 1.5 mTorr and 100 °C. After wet etching process, the surface morphologies of the films were changed dramatically depending on the microstructure and film compactness of the initial films. By controlling the surface feature, the haze factor and angular resolved distribution of the textured ZnO:Al films were improved remarkably when compared with commercial SnO₂:F films. The textured ZnO:Al and SnO₂:F films were applied as substrates for a silicon thin film solar cells with tandem structure of a-Si:H/μc-Si:H. Compared with the solar cells with the SnO₂:F films, a significant enhancement in the short-circuit current density of the μc-Si:H bottom cell was achieved, which is due to the improved light scattering on the highly textured ZnO:Al film surfaces in the long wavelength above 600 nm.     

RF magnetron sputtered ZnO:Al thin films on glass substrates: A study of damp heat stability on their optical and electrical properties

ZnO:Al thin films were deposited on glass substrates by RF magnetron sputtering from a powder compacted ceramic target. Structural, electrical and optical properties of the films with different thickness were characterized. The damp heat stability of ZnO:Al thin film was investigated for its application in thin-film solar cells. After the 1000 h damp heat treatment in harsh conditions of 85% relative humidity at 85 °C for all samples, a degradation of electrical properties was observed, while the transmissions of the films were almost unchanged. Thick films with a relative large grain size could form compact structure to resist the corrosion by oxygen and water molecules.     

Performance of double junction a-Si solar cells by using ZnO:Al films with different electrical and optical properties at the n/metal interface

High-quality ZnO:Al films have been prepared by using RF-magnetron-sputtering method with resistivity ranging from 10⁻¹ to 10⁻⁴ Ω cm and transmittance above 90% in visible region. We have fabricated small area (1 cm²) double junction (a-Si/a-Si) solar cells using ZnO/Al and ZnO/Ag as back contact. The conversion efficiency of double junction a-Si solar cell increases from 9.9% to 10.9% by using ZnO/Al back contact and to 11.4% by using ZnO/Ag as back contact. Effect of variation of thickness of i-layer on performance of the cell has also been studied.     

Effects of substrate temperature on the properties of facing-target sputtered Al-doped ZnO films

ZnO:Al films (Al 2.5 wt%) were deposited using a DC facing targets magnetron sputtering via two ZnO targets mixed with Al₂O₃. The structural, electrical and optical properties of the deposited films were strongly influenced by substrate temperature. Films with better texture, higher transmission, lower resistivity and larger carrier concentration were obtained for the samples fabricated at higher substrate temperature. The optimal condition for deposition of ZnO:Al film with the lowest resistivity of 3.18×10⁻⁴ Ω cm, the highest carrier concentration of 4.58×10²⁰ cm⁻³, and a transmission toward 85% in the visible range was obtained at 200 °C. This film proposes a promising future for the application of the practical window and contact layers for solar cells.     

Influence of gas ambient on the synthesis of co-doped ZnO:(Al,N) films for photoelectrochemical water splitting

Al and N co-doped ZnO thin films, ZnO:(Al,N), are synthesized by radio-frequency magnetron sputtering in mixed Ar and N₂ and mixed O₂ and N₂ gas ambient at 100 °C. The ZnO:(Al,N) films deposited in mixed Ar and N₂ gas ambient did not incorporate N, whereas ZnO:(Al,N) films grown in mixed O₂ and N₂ gas ambient showed enhanced N incorporation and crystallinity as compared to ZnO:N thin films grown in the same gas ambient. As a result, ZnO:(Al,N) films grown in mixed O₂ and N₂ gas ambient showed higher photocurrents than the ZnO:(Al,N) thin films deposited in mixed Ar and N₂ gas ambient. Our results indicate that the gas ambient plays an important role in N incorporation and crystallinity control in Al and N co-doped ZnO thin films.     

Effects of ITO precursor thickness on transparent conductive Al doped ZnO film for solar cell applications

Al doped ZnO (AZO) film was continuously deposited on ITO precursor on glass substrate by d.c. magnetron sputtering. The thickness of ITO was varied from 30 to 120 nm in order to investigate the effect of ITO thickness on crystallinity of AZO film. X-ray diffraction measurement shows that AZO film grown on ITO has an enhanced (0 0 2) preferred orientation as the ITO thickness was increased. The crystalline structure improvement of AZO film with an increase of ITO precursor thickness is due to the near-epitaxial growth of AZO on ITO precursor. As the ITO thickness was increased, mobility of AZO film by the Hall measurement was significantly increased from 5.4 cm²/V s (no ITO) to 23.6 cm²/V s (ITO 120 nm), and resistivity was about 81.7% improved from 1.99×10⁻³ to 3.63×10⁻⁴ Ω cm. The AZO films with ITO revealed excellent average transmission of visible (90.0%) and NIR (89.6%) regions, whereas those of AZO film without ITO were 82.1% and 88.1%, respectively. The haze values of AZO film with ITO of 90 and 120 nm are similar or higher than those of AZO film without ITO. The surface textured AZO film with ITO precursor is promising for optoelectronic applications such as the front TCO of thin film solar cells.     

Novel etching method on high rate ZnO:Al thin films reactively sputtered from dual tube metallic targets for silicon-based solar cells

Highly transparent and conductive aluminum-doped zinc oxide thin films (ZnO:Al) were reactively sputtered from metallic targets at high rate of up to 90 nm m/min. For the application as transparent light scattering front contact in silicon thin film solar cells, a texture etching process is applied. Typically, it is difficult to achieve appropriate etch features in hydrochloric acid as the deposition process must be tuned and the interrelation is not well understood. We thus introduce a novel two-step etching method based on hydrofluoric acid. By tuning the etch parameters we varied the surface morphology and achieved a regular distribution of large craters with the feature size of 1-2 μm in diameter and about 250 nm in depth. Microcrystalline silicon single junction solar cells (μc-Si:H) and amorphous/microcrystalline silicon (a-Si:H/μc-Si:H) tandem solar cells with high efficiency of up to 8.2% and 11.4%, respectively, were achieved with optimized ZnO:Al films as light scattering transparent front contact.     

Properties of fluorine doped ZnO thin films deposited by magnetron sputtering

Fluorine doped ZnO (FZO) films were deposited on Corning glass by radio frequency (rf) magnetron sputtering of pure ZnO target in CF₄ containing gas mixtures, and the compositional, electrical, optical, and structural properties of the as-grown films as well as the vacuum-annealed films were investigated. The fluorine content in FZO films increased with increasing CF₄ content in sputter gas. FZO films deposited at elevated temperature of 150 °C had considerably lower fluorine content and showed a poorer electrical properties than the films deposited at room temperature. Despite high fluorine contents in the films, for all the FZO films, the carrier concentration remained below 2×10²⁰ cm⁻³, leading to fairly low doping efficiency level. Vacuum-annealing of the FZO films deposited at room temperature resulted in substantial increase of Hall mobilities, reaching as high as 43 cm²/Vs. This was attributed partly to the removing of oxygen vacancies and/or the forming chemical bonds with interstitial zinc atoms by fluorine interstitials and partly to the passivation effect of excess fluorine atoms by filling in the dangling bonds at the grain boundaries. For all the films with thickness of around 300 nm, the optical transmissions in visible were higher than 80%, and increased with increasing fluorine content up to 85% for the film with highest fluorine content.     

High quality textured ZnO:Al surfaces obtained by a two-step wet-chemical etching method for applications in thin film silicon solar cells

ZnO:Al films deposited at 250 °C on Corning glass by radio frequency magnetron sputtering were studied for their use as front contact for thin film silicon solar cells. For this purpose, a two-step etching method combining different concentrations of diluted hydrochloric acid (from 0.1% to 3%) with different etching times was developed. Its influence on morphological, electrical and optical properties of the etched films was evaluated. This new etching method led to more uniform textured surfaces, where the electrical properties remained unchangeable after the etching process, and with adapted light scattering properties similar to those exhibited by commercial substrates.