Ni/Au contacts to corundum α-Ga₂O₃

Abstract

The structural, chemical and electrical properties of Ni/Au contacts to atomic layer deposited α-Ga2O3 were investigated. Ni forms a Schottky contact with α-Ga2O3, irrespectively of the post-annealing temperature. No sign of metal oxidation was observed at the metal-semiconductor interface (unlike what is observed for other metals like Ti), and instead, the metallurgical processes of the Ni-Au bilayer dominate the electrical properties. It is found that 400-450oC is the optimal annealing temperature, which allows for metal diffusion to heal gaps at the metal/semiconductor interface, but is not sufficient for Ni and Au to significantly interdiffuse and form an alloy with compositional inhomogeneities.

A 2.8 kV Breakdown Voltage α-Ga2O3 MOSFET with Hybrid Schottky Drain Contact

“…Although we cannot elaborate it quantitively, the ALD temperature does not have a significant impact on the Schottky contact, as observed from electrical characteristics at a low drain bias. It is reported that interdiffusion is marginal under an annealing temperature of 400 °C and that the Ni content was only 5% in the Ni-Au alloy [ 34 ]. The Ohmic contact exhibits a relatively mixed interface due to the formation of a Ti-Al inter-metallic phase, and oxygen vacancies facilitated the Ohmic contact by reducing contact resistance [ 35 ].…”