2.5 kV Vertical Ga2O3 Schottky Rectifier With Graded Junction Termination Extension

Abstract

This work demonstrates vertical Ga2O3 Schottky barrier diodes (SBDs) with a novel junction termination extension (JTE) comprising multiple layers of sputtered p-type nickel oxide (NiO). The NiO layers have the varied lengths to enable a graded decrease in effective charge density away from the main junction. The fabrication of this JTE obviates the etch or implantation and shows good throughput. The fabricated Ga2O3 SBDs exhibit a forward voltage below 1.9 V at the current density of 100 A/cm2, a differential specific on-resistance of 5.9 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2, and a breakdown voltage over 2.5 kV. The Baliga’s figure of merit (FOM) exceeds 1 GW/cm2 and is among the highest in multi-kilovolt Ga2O3 SBDs. Besides, the capacitance of the JTE region is extracted, allowing for evaluation of the capacitance, charge, and switching FOM of 1.7 kV-class Ga2O3 SBDs with varied current ratings. The results show good promise of Ga2O3 SBDs for kilovolt power electronics.