Surface electronic states and stability of the H-terminated Si(100) 1 x 1 surface produced by low-temperature H-plasma exposure.

Abstract

The electronic states and surface structure of H-terminated Si(100) produced by low-temperature (\ensuremath{\le}150 \ifmmode^\circ\else\textdegree\fi{}C) H-plasma exposure was studied by angle-resolved ultraviolet photoemission spectroscopy (ARUPS). After H-plasma exposure at 100 \ifmmode^\circ\else\textdegree\fi{}C and 150 \ifmmode^\circ\else\textdegree\fi{}C, the surface exhibited a 1\ifmmode\times\else\texttimes\fi{}1 low-energy-electron-diffraction (LEED) pattern. The ARUPS spectrum of the 1\ifmmode\times\else\texttimes\fi{}1 H-terminated phase showed a broad feature at \ensuremath{\sim}6 eV below ${\mathit{E}}_{\mathit{F}}$, and its angle dependence exhibited a nondispersive character. This feature was attributed to electronic states of the dihydride bonding configuration. The surface/resonance states of the Si-Si dimer bond were also identified in the ARUPS spectra, and the relative amount of monohydride structures was correlated with this feature. Surfaces prepared at 100 \ifmmode^\circ\else\textdegree\fi{}C and 150 \ifmmode^\circ\else\textdegree\fi{}C exhibited different relative amounts of monohydride and dihydride surface configurations. As the surface was annealed to 400 \ifmmode^\circ\else\textdegree\fi{}C the LEED transformed to a 2\ifmmode\times\else\texttimes\fi{}1 structure, and the transition from predominantly dihydride configurations to monohydride bonding was identified. The monohydride Si-H surface bond was stable up to 460 \ifmmode^\circ\else\textdegree\fi{}C, and the dangling-bond surface states were identified after annealing at 500 \ifmmode^\circ\else\textdegree\fi{}C.