Time Resolved Measurements of Dangling Bonds and Surface Structures

Abstract

This thesis will discuss the charge dynamics of dangling bonds (DBs) on the hydrogen terminated Si(100) surface under the effects of temperature and perturbations from local electric fields. The experimental methods are then extended towards DB chains. Electronic time resolved imaging techniques have been developed to create fast images of electron capture on a single DB - showcasing the mechanism behind atomic Negative Differential Resistance (NDR). This feature and its associated dynamics are further explored with experiments at 77 K and room temperature. A pump probe imaging technique was implemented and used to spatially capture the (+/0) transition level coming in to resonance with the valence band. It will be shown that a DB is sensitive to local fields and, once characterized, the DB can be used as a tool to probe the native charge properties of other structures on the surface. Of particular interest will be a bare dimer and DB chains of various lengths. These chains are then explored using DC, dI/dV, and time resolved methods. A tangential effort on the Si(111)-H surface will be mentioned, and will present a 6 atom Si “benzene” structure. The advantages of a symmetric surface will be discussed, and it’s potentially useful 2x1 zig-zag reconstruction upon desorption of Hydrogen.