Hydrogen adsorption on GaAs (001) reconstructions

Hydrogen adsorption on the c(4X4), (2X4), (2X6), and (4X2) reconstructions of GaAs (001) have been characterized by internal-reflection infrared spect roscopy. The infrared spectra contain up to 15 bands due to the stretching vibrations of arsenic hydrides (2150-1950 cm(-1)), terminal gallium hydride s (1950-1800 cm(-1)), and bridging gallium hydrides (1800-950 cm(-1)). Thes e features arise from hydrogen adsorption on arsenic and gallium dimers, an d second-layer arsenic and gallium atoms. The large number of peaks observe d indicates that the surface atoms exist in a variety of different chemical environments. (C) 1999 American Institute of Physics. [S0021-9606(99)71321 -8].