Normally-off AlN/β-Ga2O3 field-effect transistors using polarization-induced doping

Abstract

III-nitrides and beta-phase gallium oxide (β-Ga2O3) are currently two intensively investigated wide bandgap semiconductor materials for power electronics. Due to the relatively low lattice mismatch between the two material systems and the availability of bulk AlN, GaN and β-Ga2O3 substrates, epitaxial growth of III-nitrides on β-Ga2O3 or vice versa has been realized. However, the design of power devices by integrating the two material systems is still lacking. Here we numerically investigate an AlN/β-Ga2O3 heterostructure by taking advantage of polarization-induced doping to realize high-performance enhancement-mode transistors. Induced by polarization effects at the AlN/β-Ga2O3 interface, a 2-dimensional electron gas concentration can reach up to 8.1 × 1019 cm−3 in the channel. On top of the channel, a p-GaN gate was introduced and eventually a normally-off AlN/β-Ga2O3 field-effect transistor with tunable positive threshold voltages was realized. Furthermore, we inserted an unintentionally doped GaN back barrier layer to suppress the drain leakage current. Eventually, the transfer and output characteristics of the proposed device with different structural parameters were further investigated and analyzed in the pursuit of high-performance III-nitrides/Ga2O3-based power devices.