Determination of InP„001... surface reconstructions by STM and infrared spectroscopy of adsorbed hydrogen

The atomic structure of the InP~001! reconstructions has been identified by scanning tunneling microscopy and infrared spectroscopy of adsorbed hydrogen. The four phases, in order of decreasing phosphorous coverage, are c(232)/p(232), uP52.0 ML; (231), uP51.0 ML; s(234), uP50.25 ML, and d(234), uP 50.125 ML. The (232) consists of phosphorous dimers adsorbed onto a layer of P atoms. Removal of the P adatoms at 300 °C, produces the (231), which is terminated with a complete layer of buckled phosphorous dimers. Further annealing at 400 to 500 °C, yields the indium-rich s(234) and d(234) reconstructions. The s(234) reconstruction comprises a single phosphorous dimer in the top layer and four indium dimers in the second layer. The d(234) differs from the s(234) reconstruction in that one of the P atoms is replaced with an In atom to make an In-P heterodimer. This difference is evident by comparison of the intensities of P-H, In-H, and In-H-In stretching vibrations for the two surfaces.