Localized UV emitters on the surface of β-Ga₂O₃

Monoclinic gallium oxide (β-Ga₂O₃) is attracting intense focus as a material for power electronics, thanks to its ultra-wide bandgap (4.5-4.8 eV) and ability to be easily doped n-type. Because the holes self-trap, the band-edge luminescence is weak; hence, β-Ga₂O₃ has not been regarded as a promising material for light emission. In this work, optical and structural imaging methods revealed the presence of localized surface defects that emit in the near-UV (3.27 eV, 380 nm) when excited by sub-bandgap light. The PL emission of these centers is extremely bright-50 times brighter than that of single-crystal ZnO, a direct-gap semiconductor that has been touted as an active material for UV devices.