Forward bias stress-induced degradation mechanism in β-Ga2O3 SBDs: A trap-centric perspective

This study explores the impact of constant forward electrical stress on beta-gallium oxide (β-Ga2O3) Schottky barrier diodes (SBDs) from the prospective of defect evolution. Prolonged stress significantly increased the reverse leakage current density (JR) and forward current density (JF) under small bias and decreased the turn-on voltage (Von). Temperature-dependent current-voltage (I-V-T) analysis revealed that the reverse leakage current is dominated by Poole-Frenkel (PF) emission in both fresh and stressed SBDs, while the forward current transport mechanism transforms from thermionic emission (TE) to trap-assisted tunneling (TAT) after stress. Deep-level transient spectroscopy (DLTS) results identified an intrinsic trap E2* (EC - 0.75 eV) within the β-Ga2O3 drift layer, which is likely a Ga vacancy-related trap. The consistency of this energy level with the PF barrier proves that the increase in this trap is the main reason for the increase in JR. The spatial distribution features that the increase in trap concentration near the metal-semiconductor interface is much larger than that inside the bulk, which establishes the association between this trap and JF under small bias and Von. These findings highlight the critical role of trap evolution in SBD performance degradation under electrical stress.