Time-resolved reflection high-energy electron diffraction study of theGe(111)−c(2×8)–(1×1)phase transition

The dynamics of the $\mathrm{Ge}\mathrm{}\left(111\right)-c(2\mathrm{}\times 8)–(1\mathrm{}\times 1)$ phase transition is investigated by 100-ps time-resolved reflection high-energy electron diffraction. A laser pulse heats the surface while a synchronized electron pulse is used to obtain the surface diffraction pattern. Slow heating shows that the adatoms in $\mathrm{Ge}\mathrm{}\left(111\right)-c(2\mathrm{}\times 8)$ start to disorder at ∼510 K and are converted to a disordered adatom arrangement at 573 K. For heating with 100-ps laser pulses, the $\mathrm{Ge}\mathrm{}\left(111\right)-c(2\mathrm{}\times 8)$ reconstructed adatom arrangement starts to disorder at $584\pm 16\mathrm{K},$ well above the onset temperature of ∼510 K for the disordering of $\mathrm{Ge}\mathrm{}\left(111\right)-c(2\mathrm{}\times 8)$ observed for slow heating.