The photoluminescence of as-received or milled powder samples was reported. The results indicated that the Si powder had amorphous Si oxide and sub-oxide surface layers, and that the milling of the powder resulted in the formation of nanocrystalline amorphous Si components. An amorphous SiO2 component was formed by milling crystalline SiO2. The photoluminescence spectra of as-received Si, milled Si, and SiO2 contained similar peak shapes, peak maxima, and full-width at half-maximum values. The results for both as-received and milled Si powder appeared to rule out mechanisms for a photoluminescence which was related to an amorphous Si component, to Si-H or Si-OH bonds, or to a quantum confinement effect. In the case of SiO2 powder, the photoluminescence mechanisms did not appear to be related to Si-H or Si-OH bonds. A greatly increased photoluminescence intensity from milled SiO2 was instead related to both an increased volume fraction of the amorphous SiO2 component and to an increased density of defects which was introduced into the amorphous SiO2 during milling. It was suggested that the photoluminescence of as-received Si, of milling-induced nanocrystalline or amorphous Si, and of milled SiO2, resulted from defects (such as the non-bridging O hole center) in the amorphous Si sub-oxide or SiO2 components of the powder samples. The photoluminescence of milled SiO2 depended upon the air pressure, whereas that for as-received SiO2 did not. This suggested that new emitting centers were created by milling.

T.D.Shen, I.Shmagin, C.C.Koch, R.M.Kolbas, Y.Fahmy, L.Bergman, R.J.Nemanich, M.T.McClure, Z.Sitar, M.X.Quan: Physical Review B, 1997, 55[12], 7615-23