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

Films of alpha-Ga2O3 (Sn) grown by halide vapor phase epitaxy on sapphire with donor densities in the range 5 x 10(15)-8.4 x 10(19) cm(-3) were irradiated at 25 degrees C with 1.1 MeV protons to fluences from 10(13) to 10(16) cm(-2). For the lowest doped samples, the carrier removal rate was similar to 35 cm(-1) at 10(14) cm(-2) and similar to 1.3 cm(-1) for 10(15) 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 x 10(18) cm(-3), the initial electron removal rate was 5 x 10(3) cm(-1) for 10(15) cm(-2) fluence and similar to 300 cm(-1) for 10(16) 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 x 10(18) cm(-3) sample. The radiation tolerance of lightly doped alpha-Ga2O3 is higher than for similarly doped beta-Ga2O3 layers.