Transition density of states (TDOS) of the Si(100)2 × 1 surface derived from the L2,3VV auger lineshape compared with cluster calculations

Abstract

The termination of a silicon crystal along the (100) orientation resulting in a 2x1 reconstructed surface induces relatively large variations in the local density of states (LDOS) of the different types of surface atoms, such as the up and down dimer atom and the backbond atom. Auger electron spectroscopy (AES) is able to probe the LDOS of the silicon atom in which the L,,, core hole has been created and is therefore a candidate to analyze the LDOS of the surface atoms. A detailed analysis of the SiLz,,W Auger electron spectrum allows us to determine a high quality transition density of state (TDOS) of the Si(100)2 x 1 reconstructed surface. The resolved peaks in the TDOS were compared with previous AES, UPS and EELS measurements reported by other investigators. Quantum chemical cluster calculations were used for the interpretation of the TDOS in the actual p-like and s-like partial local density of states for different types of silicon atoms. These quantum chemical cluster calculations of the partial LDOS localized at atoms of the Si(100)2~1 surface were found to be in agreement with other types of calculations. Comparing the experimental and the calculated DOS we were able to distinguish several new peaks in the TDOS obtained with AES and to discriminate features in the experimentally obtained TDOS into local electron distributions localized at different surface atoms.