Current transport in strained <i>n</i>-Si1−<i>x</i>Ge<i>x</i>/<i>p</i>-Si heterojunction diodes

Abstract

The measurement and analysis of I-V characteristics from molecular beam epitaxially grown Si0.9Ge0.1/Si p-n diodes are presented. When a diode is forward biased the current transport is mainly injection diffusion of the holes and defect recombination within the depletion region of the n side. At reverse bias, the current comes from tunneling of holes from the top of the p-type valence band to the n-type conduction band, and also to the interface states followed by multistep recombination tunneling via defect states in the depletion region of the n side. The forward voltage drop was found to be much lower than that of Si diodes. Electron irradiation damages have opposite effects on the forward-biased I-V characteristics of Si0.9Ge0.1/Si diodes as compared to the effects observed for Si diodes.