Comparison of Direct Tunneling in Metal-GaN Schottky Junctions Using Different (k)over-right-arrow.(p)over-right-arrow Models for the Complex Bandstructure

In this work, we study the phenomenon of Direct Tunneling(DT) in Metal-n GaN Schottky junctions. We first compare tunneling current densities computed using quantum (NEGF) and the semi-classical (WKB) transport formulations, based on a single band parabolic approximation to the complex GaN bandstructure. We then estimate current densities using the WKB transport formulation, with complex bandstructures extracted from the two band (k) over right arrow.(p) over right arrow and four band (k) over right arrow.(p) over right arrow theories of the wurtzite GaN. We find that a WKB transport formulation is quite reliable for low bias values. We also find that the use of multi-band (k) over right arrow.(p) over right arrow models for calculating tunneling effective mass is necessary to estimate tunneling current densities accurately.