SURFACE ELECTRONIC-STRUCTURE OF CLEAN AND HYDROGEN CHEMISORBED GE(100)2X1 STUDIED BY ANGLE-RESOLVED PHOTOEMISSION

The electronic structure of the clean Ge(100)2 × 1 surface and the Ge(100)2 × 1-H monohydride surface has been studied in detail by angle-resolved photoemission. The surface state dispersions, Ei(k{norm of matrix}), in the [010] direction are mapped out. For the clean surface three surface states, which correspond to surface states previously reported for the Si(100)2 × 1 surface, are observed in the 1 × 1 projected bulk bandgap. A new, fourth surface state, showing high emission intensity is observed, just above the 1 × 1 projected valence band edge, around the J′ point of the 2 × 1 surface Brillouin zone. On the 2 × 1-H surface two strong hydrogeninduced surface states/resonances are observed in the energy region 4.4-5.5 eV below EF. © 1990 Pergamon Press plc.