AVS 45th International Symposium
    Surface Science Division Thursday Sessions
       Session SS-ThP

Paper SS-ThP4
Time-Resolved RHEED Studies of Ge(111)-c(2x8) <-> (1x1) Phase Transition

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Surface Science Division Poster Session
Presenter: X.L. Zeng, Old Dominion University
Authors: X.L. Zeng, Old Dominion University
B. Lin, Old Dominion University
H. Elsayed-Ali, Old Dominion University
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The dynamic behavior of Ge(111)-c(2x8) <-> (1x1) phase transition was investigated by time-resolved reflection high-energy electron diffraction which employs a 100 ps electron pulse as a RHEED probe synchronized with 100 ps 1.06 µm laser pulse to produce a transient surface temperature rise. By recording the RHEED intensities of (0,1/2) and (0,1) spots, the transient process of the reconstruction phase transition was monitored. First, our static RHEED study shows that Ge(111)-c(2x8) reconstruction state starts to disorder at the vicinity of 500K and are converted to a highly disordered adatom arrangement at 573K. Second, the time-resolved RHEED measurements are carried out by biasing the Ge(111) sample at 500K and using IR laser to produce a transient surface temperature jump as high as 130K. Under these conditions the Ge(111)-c(2x8) reconstructed adatom arrangement remains ordered up to 630K for a time duration of 400 ps, which is well above the characteristic temperature of 573K for the Ge(111)-c(2x8) <-> (1x1) phase transition.