Temperature dependent photoluminescence from porous silicon nanostructures: Quantum confinement and oxide related transitions

Abstract

Temperature dependent photoluminescence (PL) spectroscopy along with structural investigations of luminescent porous Si enable us to experimentally distinguish between the relative contributions of band-to-band and oxide interface mediated electronic transitions responsible for light emission from these nanostructures. Porous Si samples formed using high current densities (J ≥ 80 mA/cm2) have large porosities (P ≥ 85%) and consequently smaller (∼1-6 nm) average crystallite sizes. The PL spectra of these high porosity samples are characterized by multiple peaks. Two dominant peaks—one in the blue regime and one in the yellow/orange regime, along with a very low intensity red/NIR peak, are observed for these samples. The high energy peak position is nearly independent of temperature, whereas the yellow/orange peak red-shifts with increasing temperature. Both the peaks blue shift with ageing and with increasing porosity. The intensity of the blue peak increases whereas the yellow/orange peak decreases with increasing temperature, while the intensity and peak position of the very low intensity red/NIR peak appears to be unaffected by temperature, porosity, and ageing. The low porosity samples (P ≤ 60%) on the other hand exhibit a single PL peak whose intensity decreases and exhibits a very small red spectral shift with increase in temperature. From the variation of intensity and PL peak positions, it is established that both quantum confinement of excitons and oxide related interfacial defect states play dominant role in light emission from porous Si and it is possible to qualitatively distinguish and assign their individual contributions.

Luminescence of free-standing versus matrix-embedded oxide-passivated silicon nanocrystals: The role of matrix-induced strain

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Photoluminescence thermometry with alkyl‐terminated silicon nanoparticles dispersed in low‐polar liquids

“…Room‐temperature PL of the Si NCs is known to strongly depend on the molecular ambient 12 and the temperature 13, 14. Since high‐polar media (water, alcohol, etc.)…”

Analysis of optical and thermal properties of thermally oxidized mesoporous silicon layers

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