Competing self-trapped hole release and deep-level defect recombination in Ga2O3 photodetectors

Defects determine the photoresponse of β-Ga2O3 photodetectors, yet the interplay between self-trapped holes and deep-level recombination centers remains poorly understood. In this work, plasma-assisted molecular-beam epitaxy produced a (-201)-oriented film on sapphire with a sharp interface and a (400)-oriented film on 4H-SiC with an amorphous SiOx interlayer. Structural and spectroscopic measurements show markedly different dislocation and oxygen-vacancy signatures in these two heteroepitaxial systems. For the (-201)-oriented PD, the photocurrent decreased as the temperature rose to 150 °C and then partially recovered at 200 °C, driven by the thermal activation of the release of self-trapped holes. In contrast, the (400)-oriented photodetector showed a steady decrease in photocurrent, as deep-level recombination centers effectively suppressed the contribution from the release of self-trapped holes. Furthermore, the higher defect density in the (400)-oriented photodetector leads to faster response times, owing to enhanced non-radiative recombination through deep-level centers.