Structural and electronic properties of Bi-adsorbate-stabilized reconstructions on the InP(100) and Ga Asx N1-x (100) surfaces

Bismuth (Bi) adsorbate-stabilized reconstructions on the InP(100) and Ga As_x N_1-x (100) surfaces have been studied by scanning tunneling microscopy (STM) and spectroscopy (STS), x-ray photoelectron spectroscopy, and low-energy electron diffraction. With decreasing coverage, Bi is found to stabilize the (2×1), (2×8), and (2×4) reconstructions on the InP(100) surface and the (2×1) and (2×4) reconstructions on the Ga As_x N_1-x (100). STM results show that both the Bi InP (100) (2×4) and Bi Ga As_x N_1-x (100) (2×4) reconstructions can be described with the α2 -like structural model. The current-voltage curves measured by STS show the Bi InP (100) (2×1) and Bi Ga As_x N_1-x (100) (2×1) structures, which do not obey the electron counting model, to be semiconducting and metallic, respectively. Combining our experimental findings, we propose atomic models for the (2×1) reconstructions. An issue why Bi stabilizes unusual (2×1) structures is discussed.