New phase and surface melting of Si(111) at high temperature above the (7x7)-(1x1) phase transition
The surface structure of Si(111) at high temperatures (950-1380 degrees C) has been studied with reflection high-energy electron diffraction. We have found three different surface structures: (1) A relaxed bulklike structure with adatoms of 0.25 monolayer (ML) is formed (950-1210 degrees C); (2) there is a new phase where the adatom coverage decreases to 0.20 ML (1250-1270 degrees C); (3) the surface melting occurs over 1290 degrees C. The crystalline structure below the melting layer can be explained by the vacancy model missing all adatoms and 0.45 ML of atoms in the first-double layer.
Fukaya
Y
Faculty of Science & Graduate School of Integrated Science, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan.
Shigeta
Y