Determination of CN deep donor level in p-GaN with heavy Mg doping via a carrier statistics approach

Abstract

An equilibrium carrier statistics approach with a partial ionization model is proposed to determine the energy level of CN deep donors in p-type GaN with heavy Mg doping. Unlike usual compensating centers that are assumed to be fully ionized under equilibrium, partial ionization of the CN donor was taken into consideration. The energy level of the CN donor is determined to be EV + (0.20 ± 0.01) eV at elevated temperatures (∼350 K) using such a partial ionization model. The donor level for an isolated C center at a low temperature limit is further calculated considering the doping and temperature effects, which is EV + (0.32 ± 0.01) eV. Furthermore, the ionization ratio of CN is found to be dependent on the C concentration and can then be estimated to be in the range of 0.3–0.8. Such a partial ionization characteristic of CN may capture/emit free carriers during device operation and should be taken into account when analyzing device reliability.