TCAD analysis of the leakage current and breakdown versus temperature of GaN-on-Silicon vertical structures

A TCAD-based approach has been used to investigate the leakage current and breakdown regime of vertical GaN/AlGaN/Si structures at different ambient temperatures. TCAD modeling has been used to assess possible mechanisms of the forward-bias leakage current. A good agreement with experimental data has been obtained by implementing both trap-assisted and Poole-Frenkel conduction mechanisms into the deeper buffer layers, indicating that conduction is dominated by electron injection from silicon into a continuum of states at a given energy offset in the transition layer, which might be associated with conductive dislocation defects. The latter mechanisms have been proven to anticipate the onset of breakdown at high temperatures.