STRUCTURAL AND ELECTRONIC-PROPERTIES DURING THE INITIAL-STAGES OF GE-GAAS(110) INTERFACE FORMATION

Electronic and structural properties of the Ge and GaAs(110) surfaces, as well as, of the Ge-GaAs(110) interface with Ge overlayers of varying thickness on a semi-infinite GaAs substrate have been studied using the semiempirical tight-binding method combined with a local-charge-neutrality condition. Changes of the electrostatic layer potentials near the surface or interface are analyzed in a self-consistent way by iterative determinations of the optimally relaxed structure and of the related charge transfer. It is shown that the band offset of the Ge-GaAs(110) interface with Ge overlayers of varying thicknesses is independent of the surface relaxation. A band offset is established when the first Ge adlayer is adsorbed and it changes continuously with the number of Ge adlayers towards the final value of 0.52 eV for the Ge-GaAs(110) heterojunction interface formed by two semi-infinite crystals. Convergence to the heterojunction interface value is essentially reached for eight Ge adlayers. The calculated electronic structure of the systems shows that characteristic interface features do occur already for the first Ge adlayer. © 1995 The American Physical Society.