小信号アドミッタンス計算による埋め込みチャネルMOSキャパシタのC-V特性

Capacitance-voltage (C-V) characteristics of buried-channel MOS capacitors have been studied by small-signal admittance calculation. A numerical method for small-signal ac solutions of equations describing device electrical characteristics is presented. Using the method, the peculiar high-frequency C-V characteristics for buried-channel MOS capacitors are explained. It is found that the capacitance depends on measurement frequency in the accumulation region for buried-channel devices when the counter-doped layer is deep or the impurity concentration of the counter-doped layer is high. Depth profiles of various ac variables, such as current densities and carrier concentrations, are also calculated