Quasi-vertical GaN merged PN Schottky diode by using the p-NiO/n-GaN heterojunction

In this study, a novel quasi-vertical GaN-on-sapphire MPS diode is fabricated by using the p-NiO/n-GaN heterojunction. The sputtered NiO covers the bottom and sidewall of trench region perfectly, presenting a hole concentration 2.2 × 1018 cm−3 and a mobility of 0.1 cm2/V•s. Compared with the Ni-anode SBD, the SBD and NiO/GaN heterojunction parts in the MPS diode turn on consecutively, resulting in a higher turn-on voltage of about 1.6 V (at the current of 1 A/cm2) and on-resistance of 3.5 mΩ·cm2. On the other hand, the depletion regions at the heterojunction interface suppress the electric field crowding and enhance the reverse breakdown voltage effectively. The TCAD simulation shows that the electric field modulation becomes weak slightly with the increasing p-NiO interval, resulting in the increasing electric field as well as the leakage current. Those results are beneficial to realize a high-performance GaN MPS diode for power electronic device applications. •A novel quasi-vertical GaN-on-sapphire MPS diode is fabricated by using the p-NiO/n-GaN heterojunction.•The SBD and NiO/GaN PND in the MPS turn on consecutively.•The depletion regions at the heterojunction suppress the electric field crowding effectively.•Those results are beneficial to realize a high-performance GaN MPS diode.