Mg diffusion modulation strategy for high-voltage etched-and-regrown GaN p–n junctions

Abstract

Etching and p-GaN regrowth offer a practical route to fabricate lateral p–n junctions in GaN, which are the essential building blocks of advanced vertical devices. However, the spatial overlap between the defective regrowth interface and high electric field region leads to severe reverse leakage in etched-and-regrown p-n junctions. Here, we propose a Mg diffusion modulation strategy to relocate the high-field region away from the defective regrowth interface, thereby suppressing the leakage. By employing intentional Cp2Mg pre-flow and post-epitaxy annealing during p-GaN regrowth, enhanced Mg diffusion is achieved, as confirmed by secondary ion mass spectrometry. Technology computer-aided design simulations further validate the redistribution of the electric field, with the interfacial electric field intensity reduced from 2.6 to 0.02 MV/cm. Consequently, regrown GaN-on-Si quasi-vertical p–n diodes fabricated with this strategy exhibit low reverse leakage and a high blocking voltage of 757 V at 1 A/cm2, rivaling the performance of continuously grown counterparts. This work provides a reliable pathway toward high-performance regrown GaN devices for advanced power electronics.