Characterizations and luminescence properties of annealed porous silicon films

摘要

Porous silicon (PS) samples were prepared by common electrochemical etching in HF-based electrolytes. Significantly increased current density (150mA/cm~2) during anodization led to the accumulation of oxygen on the internal surface of the pores in the PS. Annealing of the samples was achieved in plasma of hydrogen for 15―30min. During annealing at higher temperature (420―50℃) for 15min or at lower temperature (250℃) for a longer time (30min), the hydride coverage of the internal surface of the pores was replaced by a high-quality suboxide partially oxidized hydride layer or suboxide layer, as was shown by the evolution of infra-red absorption spectra due to annealing. Efficient violet and blue emissions were observed in these samples, which could be the result of the recombination of non-equilibrium carriers via an impurity center in the suboxide layer. In the sample that has a suboxide partially oxidized hydride layer, the luminescence mechanism needs a further investigation.