Application of p-type NiO deposited by magnetron reactive sputtering on GaN vertical diodes

In this study, p-NiO deposited by magnetron reactive sputtering was adopted to fabricate NiO/GaN heterojunction and edge termination structure for vertical GaN Schottky barrier diodes. The contact properties of the NiO/GaN heterojunction were evaluated through a vertical pn diode. Turn-on voltage and specific on-resistance are approximately 2.27 V and 1.42 mΩ cm2, respectively. Temperature-dependent current-voltage and low-frequency noise measurements confirm that good interface and thermal stability of NiO/GaN heterojunction are obtained. The leakage current of the NiO pn diode is approximately four orders of magnitude lower than that of Schottky barrier diode, leading to an enhanced breakdown voltage. The p-NiO was selectively deposited as an edge termination structure to alleviate the electric field crowding of Schottky barrier diode, which is beneficial for enhancing the breakdown voltage.