MOS Avalanche and Tunneling Effects in Silicon Surfaces

Abstract

Avalanche generation of minority carriers was studied under pulsed-field conditions in thermally oxidized silicon surfaces. In the doping range between 5×1016 and 1×1018 cm−3 avalanche breakdown voltages and fields are in agreement with step-junction results. For lower doping, breakdown voltages are below the expected values. Avalanche light-emission observations revealed this effect to be due to field concentration at the contact edges. In the higher doping range between 1018 and 1019 cm−3 minority carriers are produced by Zener tunneling. Band bending for tunneling is 1.1 V, independent of doping.