Insight Into the Leakage Current Transport Mechanism Transformation in β-Ga2O3 SBDs Under Forward Bias Stress

The electrical stress-induced increase in forward and reverse leakage current has been commonly observed in beta-gallium oxide (beta-Ga2O3) Schottky barrier diodes (SBDs). However, the transformation of the current transport mechanism during stress has not been investigated. Its correlation with defects in the devices has also not been established. In this work, the transformation of the current transport mechanism and the defect behavior for beta-Ga2O3 SBDs during constant forward bias stress are investigated by the temperature-dependent current-voltage (I-V-T) and deep-level transient spectroscopy (DLTS) techniques, respectively. For the forward leakage current, the predominant transport mechanism transforms from thermionic emission (TE) to trap-assisted tunneling (TAT) after stress. The enhancement of TAT after stress is derived from a shorter tunneling path, which can be attributed to the generation of a shallow-level defect (E-C-0.2 eV), while for the reverse leakage current transport mechanism, the predominant transport mechanism transforms from Poole-Frenkel (PF) emission to TAT after stress. The ionization of newly generated shallow donors narrows the depletion region and reduces the distance of tunneling, which makes the carriers more likely to tunnel assisted by the defects in the stressed devices than thermally emitted.

Automated summary

The transformation of current transport mechanism and defect behavior in beta-gallium oxide Schottky barrier diodes (SBDs) under constant forward bias stress is investigated in this study. It is found that the predominant transport mechanism for both forward and reverse leakage current changes from thermionic emission to trap-assisted tunneling after stress. The generation of shallow-level defects and ionization of newly generated shallow donors contribute to the enhancement of trap-assisted tunneling.