Visible light emission from thin films containing Si, O, N, and H

Augustine, Brian H.; Irene, E. A.; He, Ying; Price, K. J.; McNeil, L. E.; Christensen, Kenneth J.; Maher, D. M.

doi:10.1063/1.359925

Cited by 113 publications

(75 citation statements)

References 45 publications

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“…Although the XPS study from Augustine et al 15 indicated that the phase separation of SiO x does not occur even after annealing at 1050°C for 30 min, it is generally agreed that the phase separation starts at a temperature of 400-700°C. Furthermore, obvious phase separation and formation of c-Si NCs have been observed by Fourier-transform infrared spectroscopy and TEM at a temperature of 900-1000°C.…”

Section: A Surface Compositionmentioning

confidence: 99%

Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

Chen

Tang

et al. 2004

Journal of Applied Physics

111

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We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiO x , 0Ͻ x Ͻ 2) films by high-vacuum annealing and dry oxidation. The SiO x films were deposited by plasma-enhanced chemical vapor deposition at different nitrous-oxide/silane flow ratios. The physical and optical properties of the SiO x films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000°C, the intermediate Si continuum in XPS spectra (referring to the suboxide) split to Si peaks corresponding to SiO 2 and elemental Si. This change indicates the phase separation of the SiO x into more stable SiO 2 and Si clusters. Raman, high-resolution transmission electron microscopy and optical absorption confirmed the phase separation and the formation of Si NCs in the films. The size of Si NCs increases with increasing Si concentration in the films and increasing annealing temperature. Two photoluminescence (PL) bands were observed in the films after annealing. The ultraviolet (UV)-range PL with a peak fixed at 370-380 nm is independent of Si concentration and annealing temperature, which is a characteristic of defect states. Strong PL in red range shows redshifts from ϳ600 to 900 nm with increasing Si concentration and annealing temperature, which supports the quantum confinement model. After oxidation of the high-temperature annealed films, the UV PL was almost quenched while the red PL shows continuous blueshifts with increasing oxidation time. The different oxidation behaviors further relate the UV PL to the defect states and the red PL to the recombination of quantum-confined excitions.

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Section: A Surface Compositionmentioning

confidence: 99%

Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

Chen

Tang

et al. 2004

Journal of Applied Physics

111

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“…12 However, the material produced was not silicon rich, and the authors ascribed the luminescence solely to defects. Their luminescence spectra exhibit a peak around 2.3 eV which shows no annealing-related redshift, and there is no evidence of silicon clusters from either x-ray photoelectron spectroscopy ͑XPS͒ or x-ray diffraction studies.…”

Section: ͓S0003-6951͑98͒03330-0͔mentioning

confidence: 99%

Luminescence efficiency measurements of silicon nanoclusters

Kenyon

Trwoga

Pitt

et al. 1998

Applied Physics Letters

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We present the results of what we believe to be the first study of the power efficiency of room temperature photoluminescence from thin films of silica containing silicon nanoclusters. Films were prepared by plasma enhanced chemical vapor deposition from silane and nitrous oxide precursors. Luminescence was excited using the 476 nm line of an argon-ion laser. We have measured power efficiencies for samples that exhibit luminescence solely due to radiative recombination of quantum confined excitons. Efficiencies around 0.04% are reported. © 1998 American Institute of Physics. ͓S0003-6951͑98͒03330-0͔Following Canham's report of visible luminescence from porous silicon, 1 there has been an explosion of interest in light emission from novel forms of nanoscale silicon. There have been a number of reports in the literature of visible and near-IR emission from silicon nanoclusters. [2][3][4][5][6] Typically, such clusters lie in the sub-100-Å diameter regime and exhibit a broad red luminescence band similar to that reported from porous silicon. Reports have been published of nanoclusters deposited onto silicon substrates and embedded within dielectric matrices such as silica. There has been much debate over the nature of the luminescence mechanism in this material and contradictory reports of its optical properties, but there is a growing consensus that, in common with porous silicon, quantum confinement of excitons within the nanoclusters plays a significant role. 7-10 Previous work by this group has addressed the nature of the luminescence mechanism and has indicated the presence of two distinct processes: radiative recombination of confined excitons within the silicon nanoclusters and defect luminescence from the surrounding matrix. 7,8 A single unique mechanism does not provide a good enough explanation of the luminescence properties of nanoscale silicon. However, whatever the mechanism, this remains a technologically important material as it makes a significant contribution to the search for a silicon-based light emitting material. For this reason, it is imperative to obtain measurements of luminescence efficiency from nanoclustered silicon. To date, despite the number of reports of luminescence from silicon nanoclusters, there have been no reported studies of luminescence efficiency from this class of material.In this letter we present the results of a study undertaken to measure photoluminescence power efficiencies of thin films of silica containing nanoclustered silicon. The films were produced by plasma enhanced chemical vapor deposition ͑PECVD͒: details of their growth can be found in Ref. 7. Films were 1-2 m thick and were grown on silicon substrates. Photoluminescence was excited using the 476 nm line of an argon-ion laser, and for the purposes of recording spectra luminescence was dispersed through a single-grating Bentham M300 monochromator and detected using a photomultiplier tube. Spectra were corrected for the spectral response of the optical system and the whole apparatus was computer controlled.For m...

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“…Some groups have reported bright, broadband emission from asgrown thin films of silicon-rich silica, 17 while other groups see nothing until their samples are annealed. 27 While some reports show a redshift of peak luminescence wavelength with increasing annealing temperature, 13,24,27 others exhibit a fixed spectral distribution. 14,28 Similarly, it is not clear whether temperature quenching of luminescence is significant in this material: some groups show a strong dependence of luminescence intensity on sample temperature, 28 others see no change on cooling samples to 70 K. 24 As yet there is no model which adequately explains the wide range of experimental observations: it seems possible that more than one mechanism contributes to luminescence.…”

Section: Introductionmentioning

confidence: 99%

“…[12][13][14][15][16][17][18] However, there is considerable uncertainty about the nature of the luminescence mechanism from silicon-rich silica. A number of possibilities present themselves: radiative recombination of confined excitons within silicon clusters ͑''quantum dots''͒, 23 defect luminescence, 24 interfacial effects at cluster surfaces, 25 and luminescence from novel siloxene molecules. 26 Each of these proposed mechanisms has its proponents and supporting experimental evidence, leading to a very confused picture.…”

Section: Introductionmentioning

confidence: 99%

The origin of photoluminescence from thin films of silicon-rich silica

Kenyon

Trwoga

Pitt

et al. 1996

Journal of Applied Physics

207

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We have carried out a study of the photoluminescence properties of silicon-rich silica. A series of films grown using plasma enhanced chemical vapor deposition over a range of growth conditions were annealed under argon at selected temperatures. Photoluminescence spectra were measured for each film at room temperature and for selected films at cryogenic temperatures. The photoluminescence spectra exhibit two bands. Fourier transform infrared and electron spin resonance spectroscopies were used to investigate bonding and defect states within the films. The data obtained strongly suggest the presence of two luminescence mechanisms which exhibit different dependencies on film growth conditions and postprocessing. We make assignments of the two mechanisms as ͑1͒ defect luminescence associated with oxygen vacancies and ͑2͒ radiative recombination of electron-hole pairs confined within nanometer-size silicon clusters ͑''quantum confinement''͒.

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Visible light emission from thin films containing Si, O, N, and H

Cited by 113 publications

References 45 publications

Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

Luminescence efficiency measurements of silicon nanoclusters

The origin of photoluminescence from thin films of silicon-rich silica

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