Identifying the Predominant Leakage Channel under Low Reverse Bias for β-Ga ₂ O ₃ Vertical Device Epitaxy on the (010) Plane

In this paper, two types of hillocks on the β-Ga 2 O 3 (010) epitaxial surface are identified, and their impact on the leakage behavior of the vertical device is investigated. The characteristics of the two types of hillocks are rectangular, elongated in the [001] direction, and square, extended simultaneously along the [001] and [101] directions. The conductive atomic force microscopy (C-AFM) measurements under low reverse bias reveal that the quantity of leakage pixels associated with type II hillocks is tens of times higher than that of type I hillocks, while the intensity of the leakage current for type II hillocks is over 5 nA compared with the picoampere level for type I hillocks. This leakage phenomenon is attributed to the observation of continuous dislocation slipping in a certain direction with interconnected void-like defects inside beneath the type II hillock. The as-fabricated Schottky barrier diode (SBD) devices, through the isolation of defect-free areas, ultimately demonstrate that type II hillocks induce several orders of magnitude higher leakage current than those of type I, identifying type II hillocks as the major leakage channel for (010) β-Ga 2 O 3 vertical devices under low reverse bias conditions.