High voltage (450 V) GaN schottky rectifiers

We fabricated high standoff voltage (450 V) Schottky rectifiers on hydride vapor phase epitaxy grown GaN on sapphire substrate. Several Schottky devic e geometries were investigated, including lateral geometry with rectangular and circular contacts, mesa devices, and Schottky metal field plate overla pping a SiO2 layer. The best devices were characterized by an ON-state volt age of 4.2 V at a current density of 100 A/cm(2) and a saturation current d ensity of 10(-5) A/cm(2) at a reverse bias of 100 V. From the measured brea kdown voltage we estimated the critical field for electric breakdown in GaN to be (2.2+/-0.7) X 10(6) V/cm. This value for the critical field is a low er limit since most of the devices exhibited abrupt and premature breakdown associated with corner and edge effects. (C) 1999 American Institute of Ph ysics. [S0003-6951(99)02409-2].