Active sites of adsorption on cleaved and sputtered indium phosphide surfaces

From the initial uptake of atomic hydrogen at room temperature the active sites on cleaved and sputtered InP(110)-surfaces were determined using high resolution electron energy loss spectroscopy (HREELS), low energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS, XAES). It is found that the In-H stretching mode intensity is dominant for the cleavage surface, which is known to be P-rich due to surface relaxation. For the Ar⁺-ion bombarded surface (In-rich) the P–H stretching mode is very strong if compared to the corresponding In-H mode. From these observations it may be deduced that both, the chemical bonding situation and the geometric configuration, are reflected in our HREELS-results. For the cleavage surface the initial adsorption for atomic hydrogen is interpreted in the framework of existing models for the (1×1) relaxation in terms of its chemical bonding configuration. The sputtered surface is assumed to be amorphous consisting of In-clusters and predominantly broken P-bonds, which are passivated after hydrogen exposure. For high hydrogen exposures, a strong decrease of the phosphor hydride lines may be interpreted as phosphine desorption.