Photoelectric Properties of Cleaved GaAs, GaSb, InAs, and InSb Surfaces; Comparison with Si and Ge

Abstract

Work function and photoelectric threshold, yield, and energy distributions are given for nearly perfect atomically clean (110) surfaces of GaAs, GaSb, InAs, and InSb of known doping cleaved in a vacuum of ${10}^{-10\mathrm{}}$ Torr, and are compared with results on cleaved (111) Si and Ge. The spectral-yield curves are made up of one or more distinct linear portions. Each of these is interpreted as a direct optical excitation in the bulk for which k is conserved during emission, and the transitions are tentatively identified. GaAs and InAs, like Si, exhibit appreciable gaps (0.76 eV for GaAs) between the Fermi level and the top of the valence band at the surfaces and show only one linear rise in yield up to 6.3 eV. GaSb and InSb, like Ge, have the Fermi level coincident with the top of the valence band at the surface, and exhibit two different linear rises in yield. Surface states, while present in sufficient density to cause band bending, do not yield appreciable emission compared to valence-band states.