Temperature programmed desorption studies of deuterium passivated silicon nanocrystals

As grown silicon (Si) surfaces are known to reconstruct in order to reduce the number of dangling bonds. Surface reconstructions of hydride-terminated Si(1 0 0) and Si(1 1 1) surfaces have already been extensively studied using temperature programmed desorption (TPD). The surfaces of nanocrystals, are yet to be probed using TPD. Si nanocrystals less than 8 nm and ranging from 50 to 200 nm in diameter are grown on SiO2 surfaces in an ultra high vacuum chamber and the as grown surfaces are exposed to atomic deuterium. Desorption spectra are interpreted using analogies to Si(1 0 0). TPD spectra show that that the nanocrystals surfaces are covered by a mix of monodeuteride, dideuteride and trideuteride species. Monodeuteride species can be isolated by selectively annealing away the dideuteride and trideuteride, monodeuteride and dideuteride species can be isolated by annealing away the trideuteride. The relative populations of the deuterides depend on particle size, and their manner of filling on nanoparticles differs from that for extended surfaces. Etching of the nanocrystal surface is observed during TPD, which is a confirmation of the presence of trideuteride species on the nanocrystal surface.