Intermediate phase silicon structure induced enhancement of photoluminescence from thermal annealed a-Si/SiO₂multilayers

Abstract

a-Si/SiO2 multilayers with different a-Si sublayer thicknesses were prepared by plasma enhanced chemical vapour deposition (PECVD). An intermediate phase silicon structure (IPSS), which is intermediate in order between the continuous random network amorphous phase and the well ordered crystalline phase, was discovered in the a-Si sublayers near the crystallization onset temperatures through Raman scattering and cross-section high resolution transmission electron microscopy (HRTEM). A strong broad photoluminescence (PL) band, consisting of two peaks centred at 773 nm and 863 nm respectively, was observed with the formation of the IPSS. Based on the analysis of the temperature dependence of PL, the strong PL emission bands centred at 863 and 773 nm are ascribed to the structural defects inside the IPSS and Si = O at the surface of the IPSS, respectively.

Raman spectroscopy of thin‐film silicon on woven polyester

“…Fitting these to discrete peaks, after setting a baseline, generally required three Gaussian components apart from the purely amorphous and microcrystaline films that had only two components in this band, see e.g. 16, 24, 25, 28, 35–38. As mentioned above, the highest wavenumber peak could be identified with the familiar crystal Si TO peak at 520 cm −1 , which shifted downwards for all of our samples.…”

“…Different models have been proposed for the growth of crystallites. It is generally accepted that when an appreciable concentration of crystallites is incorporated within a predominantly amorphous film, the TO Raman peak at ∼480 cm −1 appears to shift to lower wavenumber whilst a new peak appears at ∼494 cm −1 , being a contribution from the crystalline regions 23–25. This crystallite signature occurs at increasing wavenumber as crystallite size increases 17, 36, 50.…”

“…It is now widely known that moving from 13.56 MHz PECVD to VHF frequencies enhances the formation of micro‐crystals from silane well‐diluted in hydrogen 17, 20, which is evidenced by a shift of the amorphous TO phonon peak at ∼480 cm −1 to higher wavenumber. Even a small shift has been observed to indicate the onset of nanocrystalline growth 17, 21, although earlier papers discussed the start of nanocrystal nucleation when the shift was to 494 cm −1 22–24. By analogy with thin‐film diamond growth (from methane diluted in hydrogen) using 2.45 GHz microwave PECVD 25 and similar chemistry, these higher frequencies generate profuse atomic hydrogen for preferential etching of less‐strongly bound moieties, and are thus expected to reduce any non‐crystalline component.…”

Photoluminescence from high-pressure-annealed silicon dioxide

“…5 for the sample treated for 5 h at 1100°C under 1 GPa, the PL spectrum can be decomposed into seven components peaking at, respectively, 560 nm ͑orange͒, 610 nm ͑red͒, 675 nm ͑red͒, 740 nm ͑infrared͒, 790 nm ͑in-frared͒, 830 nm ͑infrared͒, and 950 nm ͑infrared͒. 18 The 840 nm band was observed only in the sample subjected to processing at 900°C; it should be also due to the presence of some defect centers. As depicted in Fig.…”

Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiNx/SiNy multilayers

“…For a long time, nanocrystalline silicon (nc-Si) quantum dots have attracted considerable attention for its luminescent and charge storage characteristics. [9][10][11][12][13][14] Unexpectedly, we recently discovered resistive switching behavior from nc-Si dots embedded in a SiO 2 matrix. 15 Here, we demonstrate the observation of resistive switching effects from multilayered nc-Si dots embedded in a silicon nitride matrix.…”