Abstract
Surface Debye temperatures for the Si(111)-(7×7) and the Si(111)-(√3×√3)-Ag surfaces are determined by the surface structural analysis of the reflection high-energy positron diffraction (RHEPD). Relations between surface phase transitions and root-mean-square amplitudes of surface atoms are discussed using the obtained surface Debye temperatures. An order-disorder phase transition of the Si(111)-(√3×√3)-Ag structure is discussed by the result of the structure analysis using order parameters of atomic arrangements of Ag. Difference of surface plasmon excitation processes between electron and positron beams is also discussed.