Carrier removal rates in 1.1 MeV proton irradiated α-Ga2O3 (Sn)

Abstract

Films of α-Ga2O3 (Sn) grown by halide vapor phase epitaxy on sapphire with donor densities in the range 5 × 1015–8.4 × 1019 cm−3 were irradiated at 25 °C with 1.1 MeV protons to fluences from 1013 to 1016 cm−2. For the lowest doped samples, the carrier removal rate was ∼35 cm−1 at 1014 cm−2 and ∼1.3 cm−1 for 1015 cm−2 proton fluence. The observed removal rate could be accounted for by introduction of deep acceptors with optical ionization energies of 2 eV, 2.8 eV and 3.1 eV. For samples doped at 4 × 1018 cm−3, the initial electron removal rate was 5 × 103 cm−1 for 1015 cm−2 fluence and ∼300 cm−1 for 1016 cm−2 fluence. The same deep acceptors were observed in photocapacitance spectra, but their introduction rate was orders of magnitude lower than the carrier removal rate. For the heaviest doped samples, the electron removal rate was close to that for the 4 × 1018 cm−3 sample. The radiation tolerance of lightly doped α-Ga2O3 is higher than for similarly doped β-Ga2O3 layers.