Time- and angle-resolved photoemission study of InP(110)

Time- and angle-resolved ultraviolet photoemission spectroscopy was used to study electron dynamics in the picosecond time domain on photoexcited InP(110) surfaces. A transient population in the normally unoccupied ${C}_{3}$ surface state was observed in the photoemission spectra following excitation of a bulk carrier plasma. Electron energy and momentum distributions in the ${C}_{3}$ surface state were independently followed as the population decayed. Observed nonexponential decays of approximately 300 psec duration can be attributed to equilibration of the surface and bulk populations on a subpicosecond time scale, followed by diffusion of the bulk plasma away from the surface. Band-dispersion parameters for the ${C}_{3}$ surface band were obtained. The ${C}_{3}$ band minimum was found to lie 1.47 eV above the valence-band maximum at \ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{}, the center of the surface Brillouin zone, and the surface effective mass was found to be anisotropic with values of 0.20\ensuremath{\le}${m}^{\mathrm{*}}$/${m}_{e}$\ensuremath{\le}0.24 along the 〈1\ifmmode\bar\else\textasciimacron\fi{}10〉 direction, and 0.10\ensuremath{\le}${m}^{\mathrm{*}}$/${m}_{e}$\ensuremath{\le}0.15 along the 〈001〉 direction.