表面补偿的高雾度ZnO∶Al及其在硅薄膜太阳电池中的应用

采用稀盐酸对磁控溅射法制备的平面掺铝氧化锌(ZnO∶Al,AZO)薄膜表面进行湿法刻蚀制绒,分析了盐酸浓度和刻蚀时间对AZO薄膜表面的形貌特征和光电特性的影响。研究发现,湿法刻蚀导致AZO薄膜表面呈现大尺度的陨石坑形貌特征,随刻蚀时间增加,薄膜在大于500 nm的长波范围内光学透过率可维持在70%~75%,且800nm处雾度值可高达48%,陷光能力快速增加,而面电阻率呈现逐渐增加趋势。高的盐酸浓度可以导致薄膜表面呈现较快凹型形貌特征,并可给出较高的雾度值。为了在保持高雾度值的条件下改善薄膜导电性,在2%盐酸刻蚀30 s所制备绒面沉积300 nm AZO薄膜进行厚度补偿,所获得薄膜的表面方块电阻小于10Ω/sq,以其作为前电极所制成的单结薄膜电池转换效率达到9.24%。结果表明,采用酸性刻蚀+厚度补偿方法所制备的绒面AZO薄膜可兼顾高雾度和低电阻的性能要求,是用作硅基薄膜太阳电池前电极的理想材料。

High Haze Textured ZnO:Al with Surface Compensation and Its Applications in Silicon Thin Film Solar Cell

As-deposited AZO thin films prepared by magnetron-sputtering were wet etched in diluted HCl to produce textured surface , and the effects of hydrochloric acid concentration and etching time on surface morphology , optical and electrical properties were investigated .The results indicate that the wet etched AZO film shows a large size crater morphology , a high transmittance of 70%-75%at the long wavelength after 500 nm, an increasement haze ratio as high as 48% at 800 nm, and a degradation of square resistance while the light trapping ability increases rapidly on surface of the film .The high concentration of hydrochloric acid can cause the surface of the film to exhibit a fast concave morphology and give a higher haze value .In order to improve the conductivity while maintain the higher haze ratio on surface of the film, a sputtering-compensation method was utilized to deposite the thickness of 300 nm AZO film on the textured surface of samples etched in 2%HCl for 30 s.The compensated AZO samples with high haze ratio shows a small square resistance ( less than 10 Ω/sq) , and a silicon thin film solar cell with a high efficiency 9 .24%was fabricated by using the compensated AZO film as front electrode .As a candidate of front electrode for silicon thin film solar cell , the textured AZO thin films with high haze ratio prepared by wet-etching plus sputtering-compensation method exhibit a good performance of high light trapping ability and low square resistance .