双极性半导体钝化膜空间电荷电容分析

钝化膜的空间电荷电容的测量(Mott-Schottky(M-S)曲线)是研究其半导体性质的重要手段, 双极性半导体钝化膜在耗尽态电位区M-S曲线斜率往往会发生改变, 首先建立了半导体富集态、耗尽态以及反型态空间电荷电容的统一计算公式, 进而将双极性半导体钝化膜空间电荷电容等效为钝化膜/溶液界面处电容和内层钝化膜/外层钝化膜界面处的np结电容的串联, 模拟计算结果能够很好地解释M-S曲线斜率发生改变这一实验现象. 同时, 计算结果表明, 对于双极性半导体的M-S曲线, 利用其直线部分的斜率、直线与电位坐标轴的截距来确定钝化膜的载流子浓度以及平带电位会产生一定的误差.

Analysis of the Space Charge Capacitance of Bipolar Semiconductor Passive Films

Measurement of the space charge capacitance (Mott-Schottky (M-S) plot) is an important method to study semiconductor properties of passive films. The slope of the linear part of the M-S plot of a bipolar semiconductor passive film should change in the depletion region. A uniform expression for the space charge capacitance in the accumulation, depletion and reversion regions was established. The space charge capacitance of a bipolar semiconductor passive film is regarded as capacitance at the passive film/solution interface and the np-junction capacitance at the outer layer film/inner layer film interface in series. The change of slope for the linear part of the M-S plot to the bipolar passive film is well explained by the calculated results. An error would be obtained for the bipolar passive film if the flat potential and carrier density are determined directly fromthe linear zone in the M-S plot.