(Color online) (a) and (b) Structural models for In/Si(111) surfaces with 1 ML of In: (a) 4×1-RT phase, (b) 8×2-LT phase. (c) and (d) LEED pictures taken from the corresponding surfaces: (c) 4×1-RT phase, (d) 8×2-LT phase. The electron beam energy was 88 eV. Both 8× spots and ×2 streaks are indicated with arrow heads and arrows, respectively, for the LEED from the 8×2-LT phase.
(Color online) (a) Picture and (b) schematic diagram of the LEED spots for intensity analysis for the 8×2-LT phase. (c) LEED intensity changes in the 4× and 8× spots, as well as the half-order ×2 streaky lines during the phase transition process upon cooling. The intensities were determined from the total integrated intensities of the designated regions in (a). The background intensities were subtracted, but the thermal effect (i.e., Debye-Waller effect) was not corrected. Transition temperatures (T c) were determined from the onset for the sudden appearance (for 8× and ×2) or decrease (for 4×) in the superstructure spots and streaks. The transition temperatures [indicated by vertical arrows in (c)] and the transition ranges [graded region in (c)] determined from three different set of spots/streaks coincide within 1 K.
(Color online) (a) Intensity plots of the 8× LEED spots from “nominally” clean In/Si(111)−4×1 surfaces prepared under different conditions, i.e., substrate heating current (I Si) and In deposition time (t dep), whereas the 4×1 (8×2) beams appeared exclusively for all the surfaces, except for the surface prepared with (I Si = 0.25 A, t dep = 5.5 min), where LEED showed additional weak spots from the coexisting √31×√31 phase. (b) The transition temperatures determined from (a). The lines are a guide for the eyes.
(Color online) Comparison of the intensity-temperature plots of the 8×LEED spots from the three surfaces: (a) as-deposited at higher substrate temperatures (I Si = 0.25 A, t dep = 10 min), (b) postdeposition of additional In atoms on the surface (a), and (c) as-deposit at lower substrate temperatures (I Si = 0.2 A, t dep = 8 min). Note that the intensity curves of surfaces (b) and (c) show a similar decrease in transition temperature as well as the broadening of the transitional region.
Article metrics loading...
Full text loading...