Principal Investigator Tomas Palacios
Lateral and vertical gallium nitride (GaN)-based devic- es are excellent candidates for next-generation power electronics. They are expected to significantly reduce the losses in power conversion circuits and enhance the power density. Vertical GaN devices can achieve high- er breakdown voltage (BV) and handle higher current/ power than lateral GaN devices and are therefore promising for high-voltage and high-power applications.
The development of vertical GaN power transistors has been hindered by the need to perform epitaxial regrowth or dope the layer p-type. The epitaxial regrowth greatly increases the complexity and cost of device fabrication. p-type GaN has low ratio for the acceptor activation, memory effects, and much lower carrier mobility compared to that in n-GaN.
We demonstrate a novel normally-off vertical GaN power transistor with submicron fin-shaped channels. This vertical fin transistor only needs n-GaN layers, with no requirement for epitaxial regrowth or p-GaN layers. A specific on-resistance of 0.2 m-omega·cm2 and a BV over 1200 V have been demonstrated, with a threshold voltage of 1 V rendering normally-off operation. These results set a new record performance for 1200-V class power transistors and demonstrate the great potential of vertical GaN fin power transistors for high-power applications.