It was noted that the analysis of the electronic structure and Fermi surface of 0.33 monolayers of Sn/Ge(111) and Pb/Ge(111) played an important role in understanding the phase transition from a room-temperature (√3 x √3)R30° reconstruction to a (3 x 3) reconstruction below about 200K. The increasing resolution of image-type electron analysers had now permitted the obtention of entire sets of constant-energy surfaces and energy-distribution curves. The electronic structures of Sn and Pb on Ge(111) were reviewed, and high-resolution angle-resolved photo-emission data for Sn/Ge(111)-(3 x 3) at 110K were reported. The results excluded nesting or any opening of a gap in the (3 x 3) phase at this temperature. From a comparison with density functional theoretical calculations, it was concludes that the results for the electronic structure were compatible only with a (3 x 3) unit cell; with one Sn atom displaced upwards from the other two.

The Fermi Surface of Sn/Ge(111) and Pb/Ge(111). A.Tejeda, R.Cortés, J.Lobo, E.G.Michel, A.Mascaraque: Journal of Physics - Condensed Matter, 2007, 19[35], 355008 (18pp)