Minority carrier diffusion length in GaN: Dislocation density and doping concentration dependence

Abstract

We investigated the minority carrier diffusion length in p- and n-GaN by performing electron-beam-induced current measurements of GaN p–n junction diodes. Minority electron diffusion length in p-GaN strongly depended on the Mg doping concentration for relatively low dislocation density below 108cm−2. It increased from 220to950nm with decreasing Mg doping concentration from 3×1019to4×1018cm−3. For relatively high dislocation density above 109cm−2, it was less than 300nm and independent of the Mg doping concentration. On the other hand, the minority hole diffusion length in n-GaN was shorter than 250nm and less affected by the dislocation density and Si doping concentration. We discuss the doping-concentration and dislocation-density dependence of minority carrier diffusion length.