METAL-INSULATOR-TRANSITION FOR K ON GAAS(100)-AS RICH SURFACES

Recent LD-LCAO (local density-linear combination of atomic orbitals) c alculations show that atoms deposited on the As-rich GaAs(100)-2 x 4 r econstructed surface tend to form quasi one-dimensional structures alo ng the missing rows of the semiconductor surface. We show that the 'co nduction' band associated with the K-orbitals may be described by an e ffective extended Hubbard Hamiltonian. Using Green functions technique s we study the metal-insulator transition within this model, which all ows us to establish the metallic or insulating character of a given on e-dimensional structure. We find that the transition into the metallic phase takes place when going from 5/8 to 7/8 monolayers.