Atomic-Scale Mechanistic Study of Iodine/Alcohol Passivated Si(100)

摘要

Solutions of iodine in alcohol have been shown to passivate H{sub x}-Si(100), decreasing the number of surface states. The degree of passivation depends upon the structure of the alcohol; methanol provides the most stable surface, with an order of magnitude fewer unpassivated sites than H{sub x}-Si(100). The authors experiments have allowed them to develop a mechanistic understanding of the reaction of the iodine/alcohol solution with the hydrogen-terminated surface. The passivation mechanism appears to be light activated iodination of the surface followed by nucleophilic substitution by the alcohol. Their data suggests that this methoxy-terminated surface is exceptionally stable in the cleanroom ambient because the Si-O bond and the unreactive methoxy moiety hinder further reactions with contaminants. Upon annealing, they find that the passivation is readily removed, and the surface reconstructs to clean Si(100) 2x1 without the formation of silicon carbide.