Reverse current suppression of p-GaN diode using SiOx interlayer

Abstract

p-GaN diodes exhibit large reverse currents due to poor Schottky contacts between p-GaN and metal, which hinders their application in environmentally robust power systems and GaN complementary metal–oxide–semiconductor (CMOS) integration. In this study, we have proposed a p-GaN diode structure incorporating a Si-rich amorphous SiOx interlayer that effectively suppresses the reverse current from 2.58 × 10−4 to 1.48 × 10−6 A at 10 V, a reduction of more than two orders of magnitude. Meanwhile, the forward current remains high, decreasing only slightly from 5.73 × 10−4 to 5.24 × 10−4 A at −10 V, thus maintaining high on-state current capability. X-ray photoelectron spectroscopy (XPS) reveals the oxygen-deficient nature of the SiOx layer. Temperature-dependent I–V measurements demonstrate that this layer effectively suppresses Fowler–Nordheim tunneling and thermionic field emission, which are typically responsible for the high leakage current in heavily doped p-GaN diodes. This suppression shifts the dominant conduction to variable-range hopping, leading to a significant reduction in reverse current. These findings underscore the potential of the proposed structure to achieve high-performance p-GaN devices, paving the way for next-generation GaN CMOS circuits.