Surface phase transitions of Ge(100) studied via valence band photoemission

Valence band photoemission has been carried out on Ge(100) from below room temperature to 1173 K. The c(4×2)->2×1 phase transition is accompanied by the shift of a back bond derived surface state. The high temperature 2×1->1×1 transition and a further transition at ~1075 K are evident as discontinuities in the emission intensity at the Fermi level and in the attenuation of a bulk and a surface electronic state.