Electrical Properties of Thermally Annealed β-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 β-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 β-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 β-Ga2O3 microflakes. The devices survived a high temperature up to 700°C (RTA) and endured thermal annealing for an extended time of 90 minutes at 500°C. The stable performance was observed from the β-Ga2O3 MESFET until the Schottky barrier height decreased substantially and the current modulation deteriorated significantly after an RTA at 700°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°C. The thermal stability of the electronic devices based on β-Ga2O3 microflakes motivates further studies including power switching electronics under harsh environments.