Si nanocrystals embedded in SiO 2 films were exposed to an atomic H plasma at different temperatures. Photoluminescence intensity from the nanocrystals increases with increasing exposure time, followed by saturation that depends on the exposure temperature. The saturation level depends on the final exposure temperature and shows no dependence on the thermal history of exposure. This behavior is shown to be consistent with a model in which the steady-state passivation level is determined by a balance between defect passivation and depassivation by H, with the activation energy for the passivation reaction being larger than that for the depassivation reaction.

No abstract

Porous silicon was prepared by electrochemically anodizing Si substrates exposed to an atomic hydrogen plasma. The hydrogen exposure was shown to result in a change in the photoluminescence (PL) emission spectra and a significant reduction in the pore size. A 30-min H exposure at 150 • C resulted in a fourfold increase in the PL intensity, a blueshift of about 60 nm in the peak emission wavelength, and a decrease in the pore diameter by a factor of 3. These results are consistent with enhanced passivation of Si dangling bond defects and enhanced hydrogenation of the Si substrate by atomic hydrogen.