Electrical Properties of Thermally Annealed beta-Ga2O3 Metal-Semiconductor Field-Effect Transistors with Pt/Au Schottky Contacts

Abstract

The electrical properties of the metal-semiconductor field-effect transistors (MESFETs) based on quasi-two-dimensional beta-Ga2O3 n-channel and Pt/Au Schottky gate electrode were analyzed with cumulative temperature and time of thermal annealing. Mechanical exfoliation was used to prepare the beta-Ga2O3 microflakes and the fabricated device was thermally annealed using either a rapid thermal annealing (RTA) equipment or a furnace. Raman spectroscopy was also employed to investigate the robustness of the mechanically exfoliated beta-Ga2O3 microflakes. The devices survived a high temperature up to 700 degrees C (RTA) and endured thermal annealing for an extended time of 90 minutes at 500 degrees C. The stable performance was observed from the beta-Ga2O3 MESFET until the Schottky barrier height decreased substantially and the current modulation deteriorated significantly after an RTA at 700 degrees C. The obvious change in Schottky diode characteristics and the color contrast over the whole source and drain electrodes also confirmed the failure of MESFET operation after 120 minutes of annealing at 500 degrees C. The thermal stability of the electronic devices based on beta-Ga2O3 microflakes motivates further studies including power switching electronics under harsh environments. (c) The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.