Theory of superfast fronts of impact ionization in semiconductor structures

TL;DR

This paper develops an analytical theory describing superfast impact ionization fronts in semiconductor structures, predicting plasma concentration, electric field, and voltage characteristics based on front velocity and doping levels.

Contribution

It introduces a comprehensive analytical model for impact ionization fronts that accounts for electron-hole velocity differences, enabling quantitative predictions for various semiconductor materials.

Findings

Predicts impact ionization front velocity exceeding saturated drift velocity.

Determines plasma concentration, electric field, and voltage as functions of front velocity.

Accounts for electron-hole velocity and ionization coefficient differences.

Abstract

We present an analytical theory for impact ionization fronts in reversely biased p^{+}-n-n^{+} structures. The front propagates into a depleted n base with a velocity that exceeds the saturated drift velocity. The front passage generates a dense electron-hole plasma and in this way switches the structure from low to high conductivity. For a planar front we determine the concentration of the generated plasma, the maximum electric field, the front width and the voltage over the n base as functions of front velocity and doping of the n base. Theory takes into account that drift velocities and impact ionization coefficients differ between electrons and holes, and it makes quantitative predictions for any semiconductor material possible.