LOW-ENERGY-ELECTRON-DIFFRACTION STUDY OF THE AS-STABILIZED SI(111) 1X1 SURFACE

Incorporation of As atoms into Si(111) surfaces has been performed to keep a ''1X1'' phase from being transformed into the (7X7) phase. The resulting As-stabilized surface displays a ''1X1'' low-energy-electron -diffraction pattern with diffuse spots similar to those observed on t he high-temperature (HT) ''1X1'' phase. At room temperature, the diffu se spots are observed at the (2X2) and c(2X4) Bragg positions. With in creasing temperature, the diffuse spots gradually shift toward the (ro ot 3X root 3) Bragg positions, as is theoretically predicted on the '' 1X1'' phase for the Si(111) and Ge(111) surface. These provide the cle ar evidence that the As-stabilized ''1X1'' surface consists of Si adat oms distributed randomly over T-4 sites on the bulk-terminated Si(111) surface, and corresponds to the low-temperature state of the HT ''1X1 '' phase. [S0163-1829(98)07608-5].