Abstract:
Mobility of metallic gold to interact chemically with semiconductor crystals À$^{\mathrm{III}}$Â$^{\mathrm{V}}$, arsenides and phosphides at temperatures that do not yet allow their spontaneous dissociation is experimentally confirmed. High selectivity of the interaction relatively toe crystallographic orientation of the crystal surface in contact with gold is shown. The observed catalytic effect produced by gold on dissociation of the chemical bond in these crystals is associated with presence of dimerized arsenic or phosphorous atoms on their surfaces in contact with Au. A proximity of energy positions of the lone pair electrons occupied dangling bonds of dimers of Â$^{\mathrm{V}}$ elements to Fermi level in gold ensures a possibility of electron tunneling from the dimers into gold and emergence of radical single-electron states on the dangling bonds of dimers. Subsequent processes leading to formation of Â$^{\mathrm{V}}_2$ molecules and their separation from the crystal followed by dissolution of the liberated À$^{\mathrm{III}}$ atoms in gold is discussed. Each of these processes requires less activation energy than direct dissociation of the crystal. The suggested interpretation of the interaction between À$^{\mathrm{III}}$Â$^{\mathrm{V}}$ crystal surfaces and gold provides an explanation for the observed metal penetration into volume of crystals and the resulting crystallographic configurations of formed etching pits. A preliminary analysis of the processes that ensure an emergence of areas of direct contact between crystals and gold deposited on initially oxidized surfaces is given.
Fulltext:
PDF file (5886 kB)