Theoretical analysis of band-to-band tunneling in highly-mismatched semiconductor alloys

The requirement for improved mid-infrared sensing technologies motivates the development of photodiodes displaying high signal-to-noise ratio. Key to achieving this goal is minimisation of the dark current, to which band-to-band tunneling (BTBT) contributes significantly in narrow-gap materials. We present a theoretical analysis of BTBT in narrow-gap dilute nitride semiconductor alloys, and evaluate the impact of nitrogen (N) incorporation on the BTBT current density. For low field strengths our calculations suggest the potential to reduce BTBT by exploiting the impact of N-related band-anticrossing on the complex band structure (CBS). At high fields our analysis suggests that BTBT is governed by an interplay between the impact of N incorporation on the CBS and on the conduction band edge density of states, and is approximately equal to that in a conventional narrow-gap material.