Characterization of HF-Treated Si Surfaces by Photoluminescence Spectroscopy

Abstract

The properties of Si surfaces treated in HF solution of various concentrations are characterized by photoluminescence (PL). The Si surfaces treated in 4.5%-HF solution show higher PL intensity than thermally oxidized Si, indicating low surface recombination velocity of the HF-treated Si surface. The effect of ambient gases on HF-treated Si surfaces is studied. The temporal variation of PL intensity is such that it shows an abrupt rise in nitrogen followed by saturation, and the saturated intensity shows only a slight change with time. In air or in oxygen, HF-treated Si shows a gradual or fast rise in PL intensity followed by saturation for a short period and the PL intensity eventually decreases with time presumably due to generation of recombination centers. It is suggested that the oxidation of HF-treated Si induces the formation of recombination centers at the surface.