Phase transformation mechanism of nominal Si(001) surface driven by hydrogen thermal annealing

Abstract

Abstract Herein, we report the phase transformation mechanism of the nominal Si(001) surface driven by hydrogen thermal annealing. The surface energies of H-terminated Si(001) surface with different phase structures were calculated by density functional theory. The results show that the surface phase with monoatomic steps can transform into the surface phase with diatomic steps under proper ranges of hydrogen chemical potential. Combining thermodynamic and kinetic factors, the phase transformation can’t occur when annealing temperature lower or higher than 800 °C. In addition, surface phases with different types of diatomic steps are alternately transformed through the intermediate phase with monoatomic steps and the imperfection of the transformation process gradually increases with the extension of annealing time. Finally, different experiments have been carried and the experimental results are in good agreement with the phase transformation mechanism. This study provides complete theoretical mechanism and process parameters for controlling the phase structures of the nominal Si(001) surface through hydrogen thermal annealing.