The reconstruction of P-rich InP(100) requires at least a (2x4) surface unit cell to stay semiconducting and uncharged (electron counting rule). Recently it has been shown that the much smaller (2x2) unit cell obtained from MOCVD (metalorganic vapor deposition) growth contains P-H bonds. Orientation and polarization dependent Fourier Transform Infrared Spectroscopy (FTIR) of the P-H bonds in the Attenuated Total Reflection (ATR) mode have confirmed the specific form of the (2x2) surface unit cell (T. Letzig et al.., Phys. Rev. B 71 (2005) 033308) earlier proposed by W.G. Schmidt and coworkers (W.G. Schmidt et al., Phys. Rev. Lett. 90 (2003) 126101). Surface unit cells with a higher concentration of P-H bonds also obey the electron counting rule. A c(2x2) LEED image and two matching FTIR peaks were observed when the (2x2) reconstructed surface was exposed to atomic hydrogen. The corresponding c(2x2)-2P-3H surface unit cell can be shown to form a stable surface phase (T. Letzig et al., Phys. Rev. B, submitted). The complete transformation of the (2x2) surface to this new phase is not observed since the surface deteriorates when exposed to a higher dose of atomic hydrogen.

The formation of hydrogen bonds was investigated on the P-rich InP(001) surface employing attenuated total-reflection Fourier-transform infrared spectroscopy, low-energy electron diffraction, and total-energy density-functional theory calculations. Strong evidence was found for a $c(2\ifmmode\times\else\texttimes\fi{}2)\text{\ensuremath{-}}2\mathrm{P}\text{\ensuremath{-}}3\mathrm{H}$ reconstruction with a higher hydrogen coverage than is characteristic for the metal-organic chemical-vapor deposition prepared hydrogen-stabilized $(2\ifmmode\times\else\texttimes\fi{}2)\text{\ensuremath{-}}2\mathrm{D}\text{\ensuremath{-}}2\mathrm{H}$ surface. The new surface reconstruction was formed upon exposure to atomic hydrogen. Complete transformation of all the metastable atomic configurations to form the new surface reconstruction was not achieved, since prior to this the surface began to deteriorate. The latter effect was monitored as the formation of In-H bonds. Two observations, i.e., nearly complete screening of the infrared peaks for excitation with $p$-polarized light and a pronounced redshift of P-H peaks with increasing hydrogen coverage were attributed to dipole-dipole interaction between the vibrating adsorbates.

The Fourier transform infrared spectrum of the MOCVD-grown (metalorganic chemical vapor deposition) P-rich ordered InP(001) surface was measured in ultrahigh vacuum applying attenuated total reflection. The surface was measured without carrying out any post-transfer surface preparation. The low-energy electron defraction pattern showed the well-known (2x1) structure with streaks in the [-110] direction. After exposure to activated deuterium, the different infrared spectrum revealed a pronounced peak at 2308 cm(-1), which was ascribed to P-H bonds. Polarization-dependent spectra showed the dipole moments of the P-H bonds oriented only in [001] and [-110] directions. A weak 0.8 cm(-1) splitting was measured between the symmetric and antisymmetric modes of two neighboring P-H bonds. These observations provide direct proof for two oriented P-H bonds as in the surface unit cell proposed by Hahn and Schmidt [Surf. Rev. Lett. 10, 163 (2003)]. Additional much smaller peaks with different polarization behavior varied greatly for different samples and were ascribed to defects or impurities.