The effect of kink and vertical leakage mechanisms in GaN-on-Si epitaxial layers

The connection between the kink position and vertical leakage mechanisms in GaN-on-Si epitaxial layers has been investigated. Based on combined experimental data and TCAD simulation results, we demonstrate that band-to-band tunneling and Poole-Frenkel effect greatly affect the current-voltage behaviors of GaN-on-Si epitaxial layers. Band-to-band tunneling occurring in both GaN and AlGaN layers could change a kink position, and Poole-Frenkel effect happening at high biases increases the slope of J-V at the voltage region after the kink. On the other hand, we found that the kink position is related to the depletion region width at the AlN/Si interface by numerical simulation. When the connection between the kink and leakage mechanisms was considered, numerical simulation results are consistent well with the current-voltage-temperature experimental results in GaN-on-Si epitaxial layers.