Improved numerical AC superposition method for electron energy distribution functions

Abstract

An improved AC superposition method is proposed to obtain the electron energy distribution functions (EEPFs) by reducing the effect of the high order derivative terms. In the AC superposition method, a small AC voltage is applied to the current-voltage curve, and the EEPF is obtained by the second harmonic current which is proportional to the second derivative of the current. If the AC voltage is not small compared to the electron temperature, the EEPF can be distorted by high derivative terms that are not ignorable. Thus, the proposed method uses the DC component and the second harmonics of the current to reduce the influence of the high order derivative terms. The fourth derivative term is removed and the coefficients of the higher order derivative terms become ignorable. The EEPF by this method shows that the resolution of the low energy part in the EEPFs is greatly improved. Published by AIP Publishing.