(556a) Investigation of Process Techniques for Ga2O3 Based Diodes

Monoclinic β-phase Ga₂O₃ has outstanding potential for power electronics, and high quality, large diameter bulk crystals and epitaxial layers of Ga₂O₃ are already available with a range of controllable n-type doping levels by edge-defined film-fed (EFG) growth using iridium crucibles, by Czochralski or by float zone. The direct energy bandgap of Ga₂O₃, ∼4.9 eV, yields a very high theoretical breakdown electric field (∼8 MV/cm). For power electronics, the Baliga figure-of-merit proportional carrier mobility, critical electric field and breakdown voltage, is almost four times higher for Ga₂O₃ than for GaN. Currently, the major limitation for Ga₂O₃ based device fabrication is the lack of low resistance Ohmic contacts, low damage dry etching process, and thermally stable Schottky contacts. In this work, we report a technique by employing Aluminum Zinc Oxide (AZO) to improve Ohmic contacts on Ga₂O₃, studies of etch rates and etching induced damages with Cl₂/Ar and BCl₃/Ar based discharge, surface treatment prior to Schottky metal deposition as well as Ni/Au and Pt/Au Schottky contacts, and demonstration of 2300 V breakdown voltage Ga₂O₃ Schottly diode.