Gap-states measurement of chemically vapor-deposited amorphous silicon: High-frequency capacitance-voltage method

Abstract
A high-frequency (1 MHz) capacitance-voltage method is proposed to measure the gap-state density in a chemically vapor-deposited (CVD) amorphous (a-)Si. The density is derived from the analysis of high-frequency capacitance-voltage characteristics of a CVD a-Si and n-type crystalline (c-)Si junction. The density near the Fermi level in the CVD a-Si deposited at 550 °C is obtained of the order of 1017∼1018 cm−3 eV−1. Further, the energy band diagram of CVD a-Si and c-Si junction is described, and the electron affinity of CVD a-Si is derived to be less than 3.75 eV.