GaN-based multi-two-dimensional-electron-gas-channel diodes on sapphire substrates with breakdown voltage of over 3 kV

We investigated the achievability of low specific on-resistance and high breakdown voltage by GaN diodes consisting of three, five, and eight two-dimensional-electron-gas (2DEG) channels. The anode Schottky electrode and cathode Ohmic electrode were formed on each side wall of the multi-2DEG-channel and the n-type region was formed by Si-ion implantation in the cathode electrode-formation area of each multi-2DEG-channel. With increasing number of 2DEG channels of the diodes, specific on-resistance (R(on)A) showed a tendency to decrease; R(on)A of eight-2DEG-channel diodes was as low as 12.1 m Omega cm(2). The breakdown voltage of all the fabricated diodes exceeded 3 kV. Although the electrical characteristics of the multi-2DEG-channel diodes fabricated on sapphire substrates were demonstrated, the number of cracks appearing on the epitaxial layer surface was found to increase with increasing number of 2DEG channels. Such crack formation was concluded to govern the practical limit for the number of 2DEG channels. (C) 2015 The Japan Society of Applied Physics