MIS电容器的平带电容的计算

Computation of flat-band capacitance CFB of MIS capacitor

研究半导体表面态常用Ｃ－Ｖ法，关键是要确定ＭＩＳ电容器的平带电容（ＣＦＢ）的值。通常确定ＣＦＢ的方法是根据所测得的绝缘层电容（最大电容）Ｃｉ和衬底杂质浓度──ＮＡ或ＮＤ去查找以ＮＡ或ＮＤ作参变量的（ＣＦＢ／Ｃｉ）－Ｃｉ曲线族求出ＣＦＢ来，无须计算，这是方便的。但这种曲线族往往手头上没有，且查找曲线方法本身误差较大。文中推导出公式（Ａ）和公式（Ｂ），可用有关量直接精确计算出ＣＦＢ。

In order to study the surface state of smiconductor,we usually use C-V method,the key is to decide the flat-band capacitance CFB of MIS capaciptor.To get CFB,common way is to measure the capacitance Ci of isolated layer and impurity concentration NA or NB)of the substrate firstly and then look up(CFB/Ci)-Ci curves.This method is convenient,but these curves are usually not in hand and the errors are larger.In this paper,two equations concerning these parameters are derived, through which CFB can be calculated,accurately.