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

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 108 cm-2. It increased from 220 to 950 nm with decreasing Mg doping concentration from 3× 1019 to 4× 1018 cm-3. For relatively high dislocation density above 109 cm-2, it was less than 300 nm and independent of the Mg doping concentration. On the other hand, the minority hole diffusion length in n-GaN was shorter than 250 nm 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.