STRUCTURE OF HIGH-INDEX CLEAN SI SURFACE STUDIED BY REM (HHM) SURFACE WITH M/H=1.4 TO 1.5

A flat Si surface with indices hhm (m/h = 1.4 to 1.5) is found by in-situ REM study of the [110] zone. The surface is found on an inner cylindrical surface formed in a (11BAR0) wafer and misoriented from a (111) surface by about 10.5-degrees toward the [11BAR2] direction. RHEED patterns show that the surface structure has a superperiod of seven parallel to the [11BAR0] direction and a long period perpendicular to it. REM images show fringes parallel to the [11BAR0] direction with spacing about 5 to 10 nm. The spacing changes from place to place, which indicates that the surface is a modulated structure. Finely spaced spots in RHEED patterns disappear at about 900-degrees-C suggesting a structural phase transition.