Scrutinizing Current Transport Properties in Vertical GaN Schottky Junctions

The current transport properties of Pt Schottky contacts on free standing bulk GaN measured at 300–425 K are reported in this article. The analysis on the experimental forward current characteristics based on Tung’s model, considering an effective area due to the presence of local inhomogeneous barrier, produced the Richardson constant similar to the theoretical value. The reverse leakage current characteristics at high temperatures were described well with the thermionic field emission model. Unexpectedly high leakage current at low temperatures was analytically described by using the dislocation-related tunneling current at low bias voltages. In addition, the trap-assisted tunneling was observed to contribute to the leakage current at high voltages. The result in this work is beneficial in diagnosing the properties of vertical GaN Schottky diodes, especially the role of dislocations in the leakage current.