Vertical Ga2O3 Schottky barrier diodes on single-crystal β-Ga2O3 (−201) substrates

Abstract

Owing to the large bandgap, breakdown electric field (E_b) and high carrier mobility, wide-bandgap semiconductor (e.g. SiC and GaN) based power devices have been extensively studied for next-generation power-switching applications [1-2]. Recently, a new wide-bandgap oxide semiconductor, gallium oxide (β-Ga₂O₃), has attracted attention for power-switching applications because it has an extremely large bandgap of 4.5~4.9 eV enabling a high breakdown voltage (V_br) and a high Baliga's figure of merit [3]. Furthermore, large-area and high-quality bulk substrates of Ga₂O₃ can be grown by low-cost methods, which remains a significant challenge for both SiC and GaN. Schottky barrier diodes (SBDs), with a low turn-on voltage and a fast switching speed due to majority carrier conduction, are ideal candidates for high-power and high-speed rectifiers. Recently, Higashiwaki et al. have demonstrated excellent device results, which includes SBDs with V_br ~115 V on (010) Ga₂O₃ substrates (with a net doping concentration N_D-N_A ~ 5×10¹⁶ cm^-3) [4] and SBDs with epitaxial Si-doped n-Ga₂O₃ drift layers (N_D-N_A ~ 1.4×10¹⁶ cm^-3) grown by HVPE on (001) Ga₂O₃ substrates with V_br ~ 500 V [5]. Oishi et al reported Ni-based SBDs on (-201) Ga₂O₃ with a Nd-Na ~ 1×10¹⁷ cm^-3 and V_br ~ 40 V [6]. However, no high voltage (V_br > 100 V) devices have been reported yet on (-201) Ga₂O₃, the crystal orientation readily available in up to 4 inch diameter wafer. In this work, we report Pt-based SBDs fabricated on unintentionally-doped (UID) (-201) n-type Ga₂O₃ substrates with V_br > 100 V.