Stoichiometry changes by selective vacancy formation on (110) surfaces of III-V semiconductors: Influence of electronic effects

We investigated the kinetics of thermal formation of anion vacancies and th e subsequent stoichiometry changes on (110) cleavage surfaces of III-V semi conductors by scanning tunneling microscopy. We found that the rate of spon taneous formation of monovacancies depends very sensitively on the doping o f the underlying semiconductor and the concentration of surface vacancies. It is shown that the position of the-Fermi energy at the surface is the maj or electronic influence on the energy barrier height for the vacancy format ion. We found barrier heights in the range of 1.1-1.3 eV for GaAs and InP. The physical factors affecting the vacancy formation and the surface stoich iometry are discussed in detail. (C) 2001 American Institute of Physics.