半导体/液结费米能级钉着的理论分析

Theoretial Analysis on Fermi Level Pinning at Semiconductor/Liquid Junction

在半导体/金属接触的肖脱基结理论和半导体/溶液界面结构的 Gerischer-Nozik模型的基础上,推导出半导体/液结势垒高度的关系式,并定量地分析无表面态和高密度表面态两种极限情形中的势垒高度。结果表明前者决定于半导体的亲合能和氧化还原对的电位,后者不随氧化还原对的电位和外加电位而变化,费米能级钉着在表面态。n-GaAs 电极的光电效应和电反射效应的实验结果证明理论分析的合理性。

The interface energetics for a semiconductor contacting a solution containing redox couple has been analyzed. The potential barrier height at the semiconductor /liquid junction which has been formulated depends on parameters of the semiconductor, Helmholtz double layer and surface states as well as the redox couple potential. Two limiting situations in which no surface state and large density of surface states are present have been discussed quantitatively. Fermi level pinning to the surface states is revealed in the latter. Observation on photovoltage characteristics and electrorcflection spectra of n-GaAs polyctystal electrode treated by both no etching and etching confirms reliability of the theoretical analysis.