Photoluminescence from mechanically milled Si andSiO2spowders

Abstract

The photoluminescence ͑PL͒ in as-received and milled Si and SiO 2 powder is reported. The Si and SiO 2 powder is characterized by chemical analysis, Raman scattering, x-ray photoelectron spectra, infrared absorption, x-ray diffraction, and differential thermal analysis. The results indicate that the Si powder has amorphous Si oxide and suboxide surface layers. The milling of Si powder results in the formation of nanocrystalline/ amorphous Si components. An amorphous SiO 2 component is formed by milling crystalline SiO 2 . The PL spectra for as-received Si, milled Si, and SiO 2 powder exhibit similar peak shapes, peak maxima, and full width at half maximum values. For both the as-received and the milled Si powder, experimental results appear to exclude mechanisms for PL related to an amorphous Si component or Si-H or Si-OH bonds, or the quantum confinement effect. Similarly, for milled SiO 2 powder mechanisms for PL do not appear related to Si-H or Si-OH bonds. Instead the greatly increased intensity of PL for milled SiO 2 can be related to both the increased volume fraction of the amorphous SiO 2 component and the increased density of defects introduced in the amorphous SiO 2 upon milling. It is suggested that the PL for as-received Si, milling-induced nanocrystalline/ amorphous Si, and milled SiO 2 results from defects, such as the nonbridging oxygen hole center, in the amorphous Si suboxide and/or SiO 2 components existing in these powder samples. The PL measurement for milled SiO 2 is dependent on air pressure whereas that for as-received SiO 2 is not, suggesting that new emitting centers are formed by milling.

Experimental investigation of band structure modification in silicon nanocrystals

“…Photoluminescence properties of silicon nanocrystals prepared by ball milling were previously studied by Shen et al 10 Here we present evidence of a smooth transition between bulk and nanocrystalline properties of silicon. By observation of defects characteristic for bulk crystal, we trace their behavior as slightly perturbed by volume restriction.…”

Structural evolution in nanocrystalline Cu obtained by high-energy mechanical milling: Phases formation of copper oxides

“…For some cases, the powder becomes amorphous beyond this point. Furthermore, through a large amount of published research work on the amophization of pure elements such as Si, Ge, Se [16][17][18][19][20][21], it was found that the amorphisation process has been related to crystalline phase instability, related to a lattice expansion due to a critical crystallite size refinement induced by ball milling.…”

Blackbody emission under laser excitation of silicon nanopowder produced by plasma-enhanced chemical-vapor deposition

“…Although we have not done extensive research, we have found three papers in which this hypothesis should be taken into account. The first 21 reports a supralinear dependence of the radiation emitted by laser ablated porous silicon; the second 22 finds a pressure quenching of the radiative emission of mechanically milled Si and SiO 2 powders, and the third 23 analyzes the luminescence of porous silicon after a pulsed laser excitation. In this case, the spectra have a two-peak structure.…”