Photoelectric emission from negative-electron-affinity diamond (111) surfaces: Exciton breakup versus conduction-band emission

摘要: We have recently reported that bound electron-hole pairs (Mott-Wannier excitons) are the dominant source of photoelectron emission from specially prepared [``as-polished'' C(111)-(1\ifmmode\times\else\texttimes\fi{}1):H] negative-electron-affinity diamond surfaces for near-band-gap excitation up to 0.5 eV above threshold [C. Bandis and B. Pate, Phys. Rev. Lett. 74, 777 (1995)]. It was found photoexcited excitons transport surface, break up, emit their electron. In this paper, we extend study exciton-derived include partial yield (constant final-state) analysis as well angular distribution measurements photoelectric emission. addition, find does not always dominate. Photoelectric properties in situ ``rehydrogenated'' (111)-(1\ifmmode\times\else\texttimes\fi{}1):H surface characteristically different than observed as-polished surface. The rehydrogenated has additional downward band bending compared confirmation assignment exciton breakup emission, a significant enhancement total electron when hydrogenated is increased. functional form demonstrates that, contrast conduction-band electrons component Furthermore, characteristics confirms our Fan phonon-cascade mechanism thermalization excitons.