Abstract
Measurements by low energy electron diffraction (LEED), by Auger electron spectroscopy (AES), of work function (CPD) and of surface conductance (g□) were performed at room temperature on faces (101) and (100) of SnO 2 submitted beforehand to ionic cleaning and annealing. We could identify four ranges of annealing temperatures similar to those observed for the (110) face. A reduced, amorphous and moderately conductive surface was produced below 130±20° C. Then CPD decreased by 200 meV, g□ increased dramatically and below 310±40° C recrystallization and reoxidation occurred giving, up to 400 ± 30°C, a diffuse p(1×1) structure. The latter became sharp at higher temperatures while CPD was steadily increasing. The evolution of surface stoichiometry is interpreted by a preferential sputtering of oxygen supplemented by tin segregation followed by oxygen diffusion from the bulk. Space charge theory indicates the existence of a degenerate accumulation layer at the surface.
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