Dislocation-controlled reverse leakage and temperature-dependent transport in quasi-vertical GaN-on-Si Schottky barrier diodes

Abstract Temperature-dependent reverse leakage in quasi-vertical GaN-on-Si Schottky barrier diodes was investigated and linked to material growth conditions through structural characterization. The NH 3 pre-dose prior to AlN nucleation was varied from 60 to 190 s, modifying the total threading dislocation density (TDD), relative proportions of dislocation types and wafer bow. An intermediate NH3 pre-dose resulted in the lowest atomic force microscopy (AFM)-derived TDD of (1.5±0.4)×10 9 cm -2 , the lowest proportion of edge-type dislocations and desirable convex wafer bow. This correlated with the lowest reverse leakage (mostly invariant to measurement temperature) and the highest breakdown voltage of ~ -160 V. Conversely, lower NH 3 pre-dose resulted in higher AFM-derived dislocation density ((2.3±0.5)×10 9 cm -2 ), a reduced breakdown voltage (~ -140 V), an undesirable concave bow of ~2 μm, and increased thermally-activated leakage paths. This behavior is consistent with trap-mediated transport such as Poole-Frenkel type emission from electrically-active dislocation-related states. The highest NH 3 pre-dose resulted in the highest AFM-derived dislocation density of (3.0±0.4)×10 9 cm -2 , anomalous forward IV characteristics associated with surface v-pits, the highest leakage and the lowest breakdown voltage of ~ -50 V. The temperature dependence of this sample indicates additional contact/interface or localized shunt leakage contributions. Our results demonstrate that even a narrow distribution of total TDD and small changes to dislocation type strongly impact the electrical characteristics and alter the dominant physical transport mechanisms. This highlights how targeted epitaxial growth optimization can enable low-cost GaN-on-Si platforms to approach the performance metrics required for high voltage, mass market power electronics.