Leakage mechanism of quasi-vertical GaN Schottky barrier diodes with ultra-low turn-on voltage

The leakage mechanism of quasi-vertical GaN Schottky barrier diodes (SBDs) with ultra-low turn-on voltage has been investigated. By using a tungsten anode, the turn-on voltage is 0.39 V and the average breakdown electric field is above 1 MV cm−1. Under low reverse bias, the thermionic emission is dominated. When the reverse bias increases to a certain value, the increased electric field promotes the electron hopping along the threading dislocation in the bulk GaN layers, and variable range hopping (VRH) becomes the main leakage current mechanism. The leakage difference between tungsten-anode and nickel-anode SBDs is reduced to one order of magnitude due to the VRH mechanism.