The electronic structure of cleaved silicon (111) surfaces following adsorption of aluminium

The authors find that the presence of less than 4*10 13 atoms per cm 2 of aluminium on a clean cleaved silicon (111) surface may lead to a phase transition from the well known reconstructed 2*1 to an apparent 1*1 structure. The phase transition is accompanied by a drastic redistribution of surface electronic states and the main features of angle-resolved photoemission experiments are considered in terms of recent theories of reconstructed and unreconstructed surfaces. Possible mechanisms involved in the phase transition are briefly discussed.