Performance and reliability of β-Ga2O3 Schottky barrier diodes at high temperature
Karen N. Heinselman, Patrick Walker, Andrew G. Norman, Philip A. Parilla, David S. Ginley, Andriy Zakutayev
Abstract
Beta-gallium oxide (β-Ga2O3) is an ultrawide bandgap semiconductor that has potential for power electronic applications and devices operating at high temperatures. Particularly important for these applications are its 4.9 eV bandgap, facile electron doping, and the ability to grow β-Ga2O3 crystals from the melt. In this work, vertical β-Ga2O3 Schottky barrier diodes were fabricated using Pt Schottky and Ti-based Ohmic contacts and Au contact pads on unintentionally doped n-type, (2¯01)-oriented single crystal substrates. The diode’s temperature-dependent electrical properties up to 400 °C were investigated, and the Pt/Ga2O3 Schottky barrier height was determined to be close to 1.2 eV. The degradation of the contacts over multiple cycles up to 400 °C was observed, resulting in a significant increase in series resistance of the diodes by 1000× at ambient temperature after they were cycled. According to electron microscopy measurements, this degradation is likely due in part to the migration and oxidation of Ti at the top surface of the Au contact pads. This degradation highlights the need for further research and development to ensure stable Ohmic and Schottky contacts to Ga2O3 at temperatures above 400 °C.