Stability and electric conductivity of Si-metal surface reconstructions during amorphous Si deposition

Abstract

Surface reconstruction stability of Si(111) √3 × √3-In, Si(111) √3 × √3-Al, Si(111) 4 × 1-In, Si(111) √3 × √3-Ag, Si(111) 3 × 1-Ag, Si(100) 2 × 1, Si(100) 2 × 3-Na and Si(100) 4 × 3-In surface phases has been studied during Si deposition by observation of electron diffraction fundamental and fractional-order spot attenuation. Previous works regarding their atomic structure have enabled to recognize the relationship between the stability and composition of surface phases. It was found that ordered surface phases consisting of adsorbate atoms atop the bulk-like terminated Si surface are unstable and become disordered at the early stages of amorphous (α) Si deposition. The deposition of α-Si on surface reconstructions at 100K results in a delay of disorder process. It was shown that crystal structure of surface phases formed by both adsorbate and substrate atoms has high stability at room temperature (RT) as well as at low temperature (LT). The surface conductivity of buried surface phases was investigated in situ. It was found that the surface conductivity correlates with surface structures’ stability, i.e. the conductivity of ordered surface phases consisting of only adsorbate atoms decreases rapidly, while surface reconstructions that are stable to α-Si deposition are characterized by permanent conductivity.