Chemical effects of hydrogen on surface damaging process in gas-ion irradiated alumina

Damaging processes of crystalline alumina (α-Al2O3) near the surface region by gas ion (H+, He+, Ar+, 0.5–5 keV) irradiation at various temperatures were examined by the Auger electron spectroscopy (AES) and reflection high-energy electron diffraction (RHEED). Phenomenological kinetic equations, which took spontaneous thermal recovery and the chemical effect between hydrogen and the target atoms, were derived to explain the RHEED intensity. The present results showed that the surface damage by low-energy inert gas irradiation could be understood simply by the ratio of dpa (displacement per atom) rates due to nuclear stopping. In the case of H+ irradiation, on the other hand, electronic excitation and hydrogen accumulation in the matrix with some chemical bonding to the matrix atoms significantly affected the damaging rate, the effects of which were semi-quantitatively extracted.