In this study, the focused ion beam (FIB) Ga+ irradiation damage on β-Ga₂O₃ Schottky diode structure under different ion energies were tested, and the effective recovery of diode characteristics after rapid thermal annealing (RTA) post-annealing were also studied.

β-Ga₂O₃ based Schottky diodes have attracted increasing attention because of the prospects for use in next-generation high-power electronics. Focused ion beam (FIB) machining is one of the newest processing techniques, which is mainly used in semiconductor and chip manufacture and transmission electron microscopy (TEM) sample preparation. During FIB sample preparation, the energetic Ga ions are incident onto the sample to induce physical sputtering of the material, which in turn, modifies its chemical composition, crystallinity and electrical properties. It has been found in many studies that 20-30 nm amorphous layer can form on silicon after irradiation with 30 keV Ga ions. From our previous study, the FIB ion beam induced damages could cause significant degradation on diode on-resistance and turn-on voltage. Milling at lower energy has been used to reduce the electrical damage. However low energy milling is more time consuming and less precise. Short-time, high-temperature post-annealing treatments, such as RTA has been proved could remove the crystal damage. Thus, there is a great need to determine the maximal ion beam energy and post-annealing temperature for FIB without degrading diode characteristics.

In this work, energies ranging from 2 keV to 30 keV were employed to mill off a part of Ga₂O₃ epi-layer and Schottky diodes were fabricated on milled surface. Forward IV characteristic shows less degradations with lower ion beam energies. For the diodes exposed to 2, 5, and 10 keV Ga+ ion beams exhibited significant recovery of diode on resistance and turn-on voltage after 300°C RTA annealing. For the diodes exposed to 30 keV Ga+ ion beams recovered significantly after 400 °C annealing. In conclusion, decreasing the FIB energy shows effective alleviations on the FIB damage, and post annealing treatment effectively recovered the damage from Ga+ implantation.

This is the first time the thermal annealing treatment was performed for Ga₂O₃ Schottky diode recovering from FIB cutting, it is an effective and simple way to mitigate the degradation, especially for higher ion beam energies. This work could broaden the FIB’s usability and release tremendous potential as a specimen preparation and imaging tool in materials science applications.