ZnO/Si异质结的光电转换特性研究

利用直流反应溅射方法在p型Si衬底上生长掺Al的n型ZnO薄膜，测量了由n型ZnO薄膜和p型Si衬底组成的异质结在黑暗和光照条件下的I-V特性,结果表明该异质结具有优良的整流特性，而且在光照条件下的反向电流迅速增大并很快趋于饱和.通过测量ZnO薄膜的光电流和异质结的光电压的光谱响应，初步分析了异质结的光电转换机理.测量结果显示，在入射光波长为380nm时光电流强度明显下降，反映出光电流与ZnO薄膜禁带宽度的密切关系；同时还发现，在与ZnO禁带宽度相对应的波长前后所产生的光生电压方向相反.推测这一现象与异质结的能带结构密切相关. 关键词： ZnO薄膜 异质结 光电转换 光谱响应

Study on the photovoltaic conversion of ZnO/Si heterojunction

ZnO:Al films have been prepared on p-type Si substrates by DC reactive sputtering. Hall measurement showed that the ZnO:Al films exhibited apparent n type conductivity. I-V characteristics in darkness and under illumination have been performed. It was found that the illumination reverse current increased rapidly with the applied voltage and was saturated at -1 V, which was obviously different from that in darkness. This phenomenon resulted from the photovoltaic effect of heterojunction. Furthermore, in order to investigate the mechanism of photovoltaic conversion, photoconductivity and photovoltage response spectra have been studied. It was found that the photocurrent decreased sharply when the wavelength was 380 nm, and the direction of photovoltage response also changed at this point. It was presumed that this phenomenon has a close relationship with the energy band structure of the heterojunction.