The hydrogen adsorption on GaAs and InP surfaces was studied by high resolution electron energy loss spectroscopy (HREELS). The stretching vibration modes of Ga-H,As-H, In- H and P-H bonds corresponding to different energy loss peaks in the spectra were all observed. However, the As-H vibration mode was usually confused with Ga-H“Phonon echo”peak which is the Ga-H vibration mode plus an optical surface phonon loss. The identifying of As-H from the“Phonon echo”peak could be done only by comparing the relative intensities of the loss peaks. The experimental HREELS show that the bonding between the adsorbed hydrogen and the surface atoms was determined largely by the surface atomic structure and electron distribution. For the GaAs(111) surface, only surface Ga atoms form bonds with the hydrogen under low exposure, while at high exposure both As-H and Ga-H bonds could be formed. On InP(111) surface which was treated by annealing under phosphorus pressure, in addition to the In-H bond the P-H bond was formed even at low exposure. Only P-H loss peak could be seen on InP(111), which suggested that such surface was fully terminated with P atoms. In the case of forming facets on (111) surface, both surface group 111 and group V atoms could from bonds with hydrogen.
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