Demonstration of beta-(AlxGa1-x)(2)O-3/Ga2O3 double heterostructure field effect transistors

Abstract

In this work, we demonstrate modulation-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 double heterostructure field effect transistors. The maximum sheet carrier density for a two-dimensional electron gas (2DEG) in a beta-(AlxGa1-x)(2)O-3/Ga2O3 heterostructure is limited by the conduction band offset and parasitic channel formation in the barrier layer. We demonstrate a double heterostructure to realize a beta-(AlxGa1-x)(2)O-3/Ga2O3/(AlxGa1-x)(2)O-3 quantum well, where electrons can be transferred from below and above the beta-Ga2O3 quantum well. The confined 2DEG charge density of 3.85 x 10(12) cm(-2) was estimated from the low-temperature Hall measurement, which is higher than that achievable in a single heterostructure. Hall mobilities of 1775 cm(2)/V.s at 40 K and 123 cm(2)/V.s at room temperature were measured. Modulation-doped double heterostructure field effect transistors showed a maximum drain current of I-DS = 257mA/mm, a peak transconductance (g(m)) of 39 mS/mm, and a pinch-off voltage of -7.0 V at room temperature. The three-terminal off-state breakdown measurement on the device with a gate-drain spacing (L-GD) of 1.55 mu m showed a breakdown voltage of 428 V, corresponding to an average breakdown field of 2.8 MV/cm. The breakdown measurement on the device with a scaled gate-drain spacing of 196 nm indicated an average breakdown field of 3.2 MV/cm. The demonstrated modulation-doped beta-(AlxGa1-x)(2)O-3/Ga2O3 double heterostructure field effect transistor could act as a promising candidate for high power and high frequency device applications. Published by AIP Publishing