Thermal and photochemical decomposition pathways of AsH3 on GaAs(100): Implication for atomic layer epitaxy

Abstract
We report spectroscopic evidence for the thermal and photochemical decomposition pathways of arsine (AsH3) adsorbed on Ga‐rich GaAs(100). Arsine adsorbs molecularly on the Ga‐rich GaAs surface at 120 K and dissociates upon either heating to above 200 K or irradiation with 6.4 eV photons. The dissociation of arsine is accompanied by the formation of surface Ga‐H species, which is both thermally and photochemically more stable than surface AsHx. This implies that the removal of hydrogen from Ga is the rate‐limiting step in the initial stage of As deposition from AsH3 in the thermal or photoassisted atomic‐layer epitaxy of GaAs.