Journal
JOURNAL OF APPLIED PHYSICS
Volume 107, Issue 6, Pages -Publisher
AMER INST PHYSICS
DOI: 10.1063/1.3330658
Keywords
colloids; defect states; elemental semiconductors; nanofabrication; nanoparticles; nanoporous materials; oxidation; phonons; photoluminescence; porous semiconductors; semiconductor quantum dots; silicon; silicon compounds; spectral line shift; surface states; suspensions
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Funding
- Department of Science and Technology, India, University Grant Commission, India [32-102/2006]
- Indo-U.S. Science and Technology Forum
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We report synthesis and luminescent characteristics of core-shell nanostructures of silicon and silicon oxide having two different morphologies-spherical (nanodot) and rodlike (nanorod), prepared by controlled oxidation of mechanically milled crystalline silicon and by exfoliation of the affected layer of porous silicon. Colloidal suspensions of these nanostructures exhibit intense room temperature photoluminescence (PL), detectable with the unaided eye. PL band peak energies of the colloidal suspensions formed from porous silicon are blue shifted by similar to 1 eV compared to the as-prepared films on silicon substrate. In addition, PL spectra of all the colloidal suspensions blueshift with increase in excitation energy but the PL peaks of as-prepared porous silicon are independent of excitation. However, shape of the nanocrystals (spherical or rodlike) is found to have little effect on the emission spectra. These observations are explained in terms discretization of phonon density of states and electronic transitions involving surface defect states and quantum confinement induced widened band states.
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