Annealing of dry etch damage in metallized and bare (-201) Ga₂O₃

The surface of single-crystal (-201) oriented β-Ga₂O₃ was etched in BCl₃/Ar inductively coupled plasmas under conditions (an excitation frequency of 13.56 MHz, a source power of 400 W, and a dc self-bias of -450 V) that produce removal rates of ∼700 Å min^-1. Annealing at 400 and 450 °C was carried out after etching on Ni/Au Schottky diodes formed on the surface either before or after the annealing step. Current-voltage (I-V) measurements were used to extract the Schottky barrier height (Φ), diode ideality factor (n), and reverse breakdown voltage (V_RB) for plasma damaged diodes after annealing. Annealing at 450 °C was found to essentially restore the values of Φ, n, and V_RB to their reference (unetched) values on samples metallized after etching and annealing. Thermal annealing at either temperature of metallized diodes degraded their reverse breakdown voltage, showing that Ni/Au is not stable on β-Ga₂O₃ at these temperatures. Photoluminescence revealed a decrease in total emission intensity in the near band-edge region after the introduction of etch damage. Electron beam-induced current measurements showed a decrease in the minority carrier diffusion length from 350 μm in the control sample to 311 μm in the etched sample.