Investigation of forward transient characteristics of vertical GaN-on-GaN p-n diodes

Transient characteristics of vertical GaN diodes fabricated on bulk GaN substrates are investigated. When forward biasing the diodes using discrete pulses, the results yield quasi-static I-V curves with two different on-resistances and two turn-on stages. Transient waveforms measured at different voltages are then used to explain the observed behavior and underlying physics. A relatively large overshoot voltage is also observed at the very beginning of the transient voltage waveform, indicating that a relatively long time is required to transition the GaN diode from the high to low resistance state.