Si基底上不同厚度TiO_2薄膜表面光伏特性研究

The Study of the SPV Properties of TiO_2 Thin Films of Different Thickness on Si Substrates

在p-型Si片基底上通过甩膜焙烧形成不同厚度的锐钛矿型TiO2薄膜,发现不同厚度薄膜的表面光伏特性差别很大,随着多次扫描光伏响应变化也不同.在TiO2膜很薄的情况下,Si与TiO2分别表现各自的光伏特性,说明上层TiO2薄膜对界面态的影响小;随着TiO2膜厚度的增加,其对界面态的影响增强,表现为界面主导的光伏响应.进一步的实验表明,上层薄膜的电荷密度大时,对界面态的影响强,光电压谱上明显表现出界面的作用;而当上层薄膜的电荷密度足够小时,对界面态的影响弱,使得组成界面的物质表现各自的光伏特征.实验同时表明表面光伏技术对表面和界面均敏感,控制适当的条件可以得到表面主导或界面主导的光伏响应特征.

TiO2 thin films of different thickness were formed on p-type Si substrates by sol-gel methods. Their SPV properties vary greatly with different thickness. When the film is very thin, the Si and TiO2 represent their own SPV properties respectively. This means that the interaction between the upper films and the interface states is weak. While increasing the thickness of the films, the interface states may become a dominant factor in SPV properties. It is due to the fact that the interaction between the upper films and the interface states is strong. Further experiment on the interaction between the upper films and the interface states is dominated by the charge densities of the t, pper films. The experiment also shows that SPV technique is sensitive to buried interface as to the external surface.