Reflection high-energy electron diffraction and photoemission study of GaSb(100) reconstructions

The clean GaSb(100) surface exhibits a variety of reconstructions, including a c(2×10), a c(2×6), and a (1×3)/c(2×6), in order of a decreasing surface Sb/Ga ratio. Core-level photoemission spectroscopy and reflection high-energy electron diffraction were employed to study each of these reconstructions in detail. Our results show that the c(2×6) and (1×3)/c(2×6) surfaces have significantly different stoichiometries and core-level line shapes, and are, in fact, different reconstructions, rather than variations of the same c(2×6) surface due to disorder. Analysis of the photoemission data taken with a wide range of incident photon energy suggests that the c(2×10) surface is very Sb rich, with more than 2 ML of Sb, while the c(2×6) has 1-2/3 ML of Sb, and the (1×3)/c(2×6) has about 1-2/3 ML of Sb with 1/3 ML of Ga atoms intermixed on the surface. Quantum-mechanical diffraction and interference effects are found to significantly affect the measurement of surface-to-bulk photoemission intensity ratios. Surface structure models are presented for each reconstruction which are consistent with the observed data.