L Whitman, Joseph A. Stroscio, Robert A. Dragoset, Robert Celotta
Cesium overlayers on room-temperature InSb(110) have been studied with scanning tunneling microscopy and spectroscopy. A two-dimensional (2D) overlayer is observed, consisting of four-atom, Cs(110)-like planar clusters arranged in a c(2 x 6) superlattice. Interestingly, current-versus-voltage (I-V) spectra exhibit a band gap of asymp} 0.6 eV, larger than the substrate band gap of asymp} 0.15 eV. The I-V spectra are very similar to those observed on the similar 2D overlayer on GaAs (110), suggesting that the measured gap is a property of the 2D Cs film. The possible origins of this insulating behavior are discussed.
Physical Review B (Condensed Matter and Materials Physics)