Interplay of vacancies, hydrogen, and electrical compensation in irradiated and annealed n-type β-Ga2O3

Positron annihilation spectroscopy, Fourier transform-infrared absorption spectroscopy, and secondary ion mass spectrometry have been used to study the behavior of gallium vacancy-related defects and hydrogen in deuterium (D) implanted and subsequently annealed β-Ga2O3 single crystals. The data suggest the implantation generates a plethora of VGa-related species, including VGa1- and VGa2-type defects. The latter’s contribution to the positron signal was enhanced after an anneal at 300 °C, which is driven by the passivation of VGaib by hydrogen as seen from infrared measurements. Subsequent annealing near 600 °C returns the positron signal to levels similar to those in the as-received samples, which suggests that split VGa-like defects are still present in the sample. The almost complete removal of the VGaib-2D vibrational line, the appearance of new weak O-D lines in the same spectral region, and the lack of D out-diffusion from the samples suggest that the 600 °C anneal promotes the formation of either D-containing, IR-inactive complexes or defect complexes between VGaib-2D and other implantation-induced defects. The degree of electrical compensation is found to be governed by the interactions between the Ga vacancies and hydrogen.