Point defect distributions in ultrafast laser-induced periodic surface structures on β-Ga2O3.

β-Ga₂O₃ has received widespread attention due to its ultrawide bandgap, which potentially permits applications in extreme conditions. Ultrafast laser irradiation of β-Ga₂O₃ provides a means for exploring the response of the material under such conditions, which could result in the generation of point defects as well as a localized modification of structural features that could yield properties that differ from the pristine surface. However, an understanding of defects generated by femtosecond laser irradiation in the vicinity of laser-induced periodic surface structures (LIPSS) remains to be explored. We correlate topographic features with optical and electronic properties by combining near-nm scale resolution cathodoluminescence with Kelvin probe force microscopy. Defects are found to correlate with crystalline order and near-surface morphology, as well as changes in work function. They are also suggested to be closely related to the formation of high spatial frequency LIPSS. These results suggest a need for precise tuning of laser irradiation conditions as well as possible post-processing to control defects in future Ga₂O₃ devices. [ABSTRACT FROM AUTHOR]