Temperature dependence of optical centers in 200 keV electron irradiated β-Ga₂O₃

In this work, the optical centers of β-Ga₂O₃ irradiated with 200 keV electrons were studied by photoluminescence (PL) spectroscopy. The oxygen vacancy-related center at 690 nm were enhanced after irradiation together with a new zero phonon line (ZPL) at 697 nm. The temperature dependence of these optical centers were carefully detailed and discussed. As the increase of measurement temperature, the ZPLs showed red-shift, intensity quenching and full width at half maximum (FWHM) increase. These data were fitted by the corresponding physical formula. Results showed compared with the 690 nm emission, the 697 nm emission had a similar intensity distribution, a weaker lattice relaxation strength, a weaker lattice vibration, and a lower thermal softness. These results indicated that the 697 nm emission was probably associated with the oxygen interstitials.