Structural and electronic properties of Bi-adsorbate-stabilized reconstructions on the InP(100) andGaAsxN1−x(100)surfaces

Abstract

Bismuth (Bi) adsorbate-stabilized reconstructions on the InP(100) and $\mathrm{Ga}{\mathrm{As}}_{x}{\mathrm{N}}_{1\ensuremath{-}x}(100)$ 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 $(2\ifmmode\times\else\texttimes\fi{}1)$, $(2\ifmmode\times\else\texttimes\fi{}8)$, and $(2\ifmmode\times\else\texttimes\fi{}4)$ reconstructions on the InP(100) surface and the $(2\ifmmode\times\else\texttimes\fi{}1)$ and $(2\ifmmode\times\else\texttimes\fi{}4)$ reconstructions on the $\mathrm{Ga}{\mathrm{As}}_{x}{\mathrm{N}}_{1\ensuremath{-}x}(100)$. STM results show that both the $\mathrm{Bi}∕\mathrm{In}\mathrm{P}(100)(2\ifmmode\times\else\texttimes\fi{}4)$ and $\mathrm{Bi}∕\mathrm{Ga}{\mathrm{As}}_{x}{\mathrm{N}}_{1\ensuremath{-}x}(100)(2\ifmmode\times\else\texttimes\fi{}4)$ reconstructions can be described with the $\ensuremath{\alpha}2$-like structural model. The current-voltage curves measured by STS show the $\mathrm{Bi}∕\mathrm{In}\mathrm{P}(100)(2\ifmmode\times\else\texttimes\fi{}1)$ and $\mathrm{Bi}∕\mathrm{Ga}{\mathrm{As}}_{x}{\mathrm{N}}_{1\ensuremath{-}x}(100)(2\ifmmode\times\else\texttimes\fi{}1)$ 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 $(2\ifmmode\times\else\texttimes\fi{}1)$ reconstructions. An issue why Bi stabilizes unusual $(2\ifmmode\times\else\texttimes\fi{}1)$ structures is discussed.