In-situ Two-dimensional Characterization for Uniformity of Au/Ni/n-β-Ga<sub>2</sub>O<sub>3</sub> Schottky Contacts under Applying Voltage by Scanning Internal Photoemission Microscopy

We applied scanning internal photoemission microscopy (SIPM) to characterize the uniformity of the Au/Ni/n-type β-Ga2O3 Schottky contacts under applied voltage of -126 V for 163 hours continuously. The standard deviation (σ) of the SIPM signal on the whole electrode using blue, bluegreen, green, and red laser beam under non-voltage application were less than 2%, and of the Schottky barrier height (qϕB) was 4.46 meV. This value was comparable for the n-SiC, n-GaN, and n-α-Ga2O3 Schottky contacts. After 163 h voltage application, the σ of qϕB on the entire electrode was 20 meV, and the decrease of the average value from 0.5 h was less than 10 meV. It shows no significant degradation and maintaining high qϕB values. We demonstrated that the SIPM method can be used to be in-situ observation for electrical uniformity of the Schottky contacts under applying high voltages.