Microscopic Control of Semiconductor Interface Reactivity.
Annual rept. no. 7, 1 Aug 84-31 Jul 85,
MINNESOTA UNIV MINNEAPOLIS DEPT OF CHEMICAL ENGINEERING AND MATERIALS SCIENCE
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In recent years a number of metal overlayers on silicon have been shown to yield an increase in silicon oxidation rate when the surface is exposed to an oxidizing atmosphere. Metals as diverse as Au, AG, Cu, Pd all give rise to promotion effects, with the production of Si-oxide phases of variable stoichiometry. In the case of Au and Cr, the Si-oxide appears to nucleate on top of the metal overlayer. To the extent that the metal atoms increase the surface reaction kinetics and do not appear directly involved in the reaction product, i.e. the surface silicon oxide, they play the role of a catalyst. Since the magnitude of the effect depends on the overlayer-silicon interface morphology, in the absence of a more precise denomination we refer to such phenomena as interface catalytic effects. The main goal of our program is to investigate the microscopic mechanisms which determine these effects, characterize the electronic and structural modifications that accompany the surface reactions, determine the stoichiometry of the reaction products andor the interface composition profile, and ultimately obtain and enhanced control of the kinetics of surface reactions with gaseous species and metals. Long term practical aplications include the synthesis of new insulating and metallic epitaxial layers on Si and GaAs and enhanced control of interdiffusion and contact stability.
- Physical Chemistry
- Solid State Physics