Ultraviolet (193 nm) laser-induced oxygen exchange and bulk diffusion in gallium arsenide native oxides: ¹⁸O experiments

Pulsed laser irradiation (193 nm, t=14 ns) at low fluence (0.045 J/cm 2) of GaAs 18O enriched native oxides leads to a very efficient oxygen exchange between 18O in the oxides and 16O coming from the surrounding atmosphere. 1000 laser pulses caused a complete exchange of oxygen from an oxide layer of ∼30-nm thickness. This showed a very high rate of oxygen self-diffusion under laser irradiation although the total oxygen content in the oxide was preserved. As this process is believed to have a threshold fluence, a model based on the hole-pair mechanism of Itoh and Nakayama [Phys. Lett. A 92, 471 (1982)] is suggested. Preferential loss of As and preferential oxidation of Ga are also observed to some extent.