π-Bonded chain structure for Ge ON Si(111)

Using pseudopotential total-energy and force methods, we have studied the atomic and electronic structure of substitutional monolayer coverage of Ge on the cleaved Si(111) surface. Our results indicate that Ge atoms form a π-chain with an energy benefit of 0.32 eV /(surface atom) relative to the ideal substitutional configuration. The π-chain structure is semiconducting, and the resulting band structure is readily distinguishable from the Seiwatz chain model. © 1987.