Improved β-Ga2O3 Schottky Barrier Diodes via thermal oxidation of titanium insertion layer

Abstract

In realm of β-Ga2O3 Schottky Barrier Diodes (SBDs), insertion layer appeared as an effective strategy for enhancing breakdown voltage. Presently, insertion layer techniques typically employed atomic layer deposition (ALD) to grow insulators with low electron affinity (e.g., Al2O3, HfO2). Although these insertion layers enhanced the reverse break-down characteristics, substantially degraded forward con-duction was also induced. In this study, a TiO2 thin layer by thermally oxidized Titanium metal was inserted to elevate the breakdown voltage and power figure of merit (PFOM) of β-Ga2O3 SBDs, while maintaining the on-resistance nearly unchanged. In comparison with the conventional met-al/semiconductor-SBD (MS-SBD), the thermally oxidized metal/insulator/semiconductor-SBD (MIS-SBD) exhibited 2.75 times elevation of breakdown voltage with only 11.6% reduction of forward current at +5V. The PFOM of the thermally oxidized MIS-SBD was enhanced by 7.6-fold compared to conventional MS-SBD, and by 15.7-fold com-pared to the counterpart ALD MIS-SBD. Analysis of the TiO2/β-Ga2O3 interface characteristics through X-ray photo-electron spectroscopy (XPS) and capacitance-voltage (C–V) measurements revealed that the thermally oxidized TiO2-SBD possesses smaller band offset and larger interface trap density (Dit) compared to the ALD counterpart, which contribute to the higher PFOM of the thermally oxidized TiO2-SBD. This novel TiO2/β-Ga2O3 structure exhibited superior electrical properties, providing potential solution for high performed SBD.