SiC隐埋沟道MOS结构夹断模式下的C-V特性畸变

C-V Characteristic Distortion in the Pinch-Off Mode of a Buried Channel MOS Structure in 4H-SiC

用数值和解析的方法研究了SiC隐埋沟道MOS结构夹断模式下C-V特性的畸变.隐埋沟道MOSFET中存在一个pn结,在沟道夹断以后,半导体表面耗尽区和pn结耗尽区连在一起,这时总的表面电容是半导体表面耗尽区电容和pn结电容的串联,使埋沟MOS结构的C-V特性发生畸变.文中通过求解泊松方程,用解析的方法分析了这种畸变发生的物理机理,并对栅电容进行了计算,计算结果与实验结果符合得很好.

The distortion of the C-V characteristics of a SiC buried-channel MOS structure is presented. It is difficult to characterize the gate capacitance because there is a pn junction in buried-channel MOSFETs. The surface depletion region and nside space-charge region merge when the channel is punched through. In this case,the total surface capacitance is the sum of the surface depletion region capacitance and the pn junction capacitance,and the C-V characteristics are distorted. The analytic expression of gate capacitance in the pinch-off mode is obtained by solving Poisson＇s equation. The C-V characteristics in the pinch-off mode are analyzed on a fundamental physical level. The gate capacitance calculated with the model agrees well with experimental results.