BENDING AND STRETCHING VIBRATIONS OF HYDROGEN AND DEUTERIUM AT GAAS(110) SURFACES

Vibrations at hydrogen and deuterium covered GaAs(110) surfaces were i nvestigated by high resolution electron energy loss spectroscopy. With semi-insulating crystals, bending modes of H and D were found at 515 and 387 cm(-1) (63.9 and 48 meV), respectively. After large exposures when substrate bonds are broken scissor modes at 1000 cm(-1) (124 meV) for As-H-2 and at 752 cm(-1) (93.2 meV) for As-D-2 groups were observ ed. In the low-coverage regime two components of the Ga-H stretching v ibration at 1830 and 1850 cm(-1) (226.9 and 230.6 meV) were resolved. They may be explained by Ga-H dipole-dipole interactions.