High-temperature phase transitions at the Ge(110) surface

The Ge(110) surface has been investigated by core-level and valence band (V B) photoemission spectroscopy as a function of the temperature starting fro m the room temperature c(8 x 10) reconstructed surface up to 1196 K. Eviden ce of a phase transition is found at about 750+/-50 K from core-level and V B data analysis. VB photoemission shows that above 750 K the Ge(110) surfac e acquires an increasing metallic character up to 1110 K where a sudden, in tense jump of the emission intensity at the Fermi level is observed, At hig her temperatures up to 1196 K, a finite and constant density of states is o bserved, indicating the presence of a metallic surface layer. (C) 2000 Else vier Science B.V. All rights reserved.