The effect of HF etching of the silicon oxide shell covering the surface of Si nanocrystals (NCs) on the subsequent room-temperature atmospheric oxidation of Si-NCs has been investigated by means of photoluminescence measurements, Fourier transform infrared spectroscopy, and electron paramagnetic resonance spectroscopy. After the HF etching, the surface of Si-NCs is found to be H terminated. The HF etching also restructures the surface of Si-NCs. This leads to a decrease in the incorporation of O during subsequent oxidation, which finally results in silicon suboxide Si O1.9. In contrast, without the HF etching stoichiometric Si O2 is formed. A smaller ratio of O to Si in the silicon oxide results in a higher density of defects. This contributes to a more significant oxidation-induced decrease in the intensity of photoluminescence from Si-NCs after the HF etching than without the HF etching.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Feb 13 2007|