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Effect of thermal treatment on the growth, structure and luminescence of nitride-passivated silicon nanoclusters.

Wilson PR, Roschuk T, Dunn K, Normand EN, Chelomentsev E, Zalloum OH, Wojcik J, Mascher P - Nanoscale Res Lett (2011)

Bottom Line: Silicon nanoclusters (Si-ncs) embedded in silicon nitride films have been studied to determine the effects that deposition and processing parameters have on their growth, luminescent properties, and electronic structure.The emission energy was highly dependent on the film composition and changed only slightly with annealing temperature and time, which primarily affected the emission intensity.The PL spectra from films annealed for duration of times ranging from 2 s to 2 h at 600 and 800°C indicated a fast initial formation and growth of nanoclusters in the first few seconds of annealing followed by a slow, but steady growth as annealing time was further increased.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S4L7, Canada. wilsonpr@mcmaster.ca.

ABSTRACT
Silicon nanoclusters (Si-ncs) embedded in silicon nitride films have been studied to determine the effects that deposition and processing parameters have on their growth, luminescent properties, and electronic structure. Luminescence was observed from Si-ncs formed in silicon-rich silicon nitride films with a broad range of compositions and grown using three different types of chemical vapour deposition systems. Photoluminescence (PL) experiments revealed broad, tunable emissions with peaks ranging from the near-infrared across the full visible spectrum. The emission energy was highly dependent on the film composition and changed only slightly with annealing temperature and time, which primarily affected the emission intensity. The PL spectra from films annealed for duration of times ranging from 2 s to 2 h at 600 and 800°C indicated a fast initial formation and growth of nanoclusters in the first few seconds of annealing followed by a slow, but steady growth as annealing time was further increased. X-ray absorption near edge structure at the Si K- and L3,2-edges exhibited composition-dependent phase separation and structural re-ordering of the Si-ncs and silicon nitride host matrix under different post-deposition annealing conditions and generally supported the trends observed in the PL spectra.

No MeSH data available.


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TEY-XANES spectra for (a) PECVD, (b) ECR PECVD, and (c) ICP CVD AD films at the Si K-edge. A, B, and C indicate the peak positions for Si-Si, Si-N, and Si-O resonances, respectively. The percentages in the legend refer to the excess silicon content of the SRSN films.
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Figure 3: TEY-XANES spectra for (a) PECVD, (b) ECR PECVD, and (c) ICP CVD AD films at the Si K-edge. A, B, and C indicate the peak positions for Si-Si, Si-N, and Si-O resonances, respectively. The percentages in the legend refer to the excess silicon content of the SRSN films.

Mentions: The electronic structure was probed through X-ray absorption near edge structure experiments at the silicon K- and L3,2-edges, where differences in structure within the films can be identified by shifts in their spectral features [25-29]. The XANES measurements performed at the silicon K-edge for AD films from each system are shown in Figure 3, which reveal common trends in the Si-nc structure. The spectra of the ICP CVD films were measured from 2-μm-thick films, much larger than the information depth at either absorption edge [30], to ensure that the substrate would not contribute to the TEY or FLY. However, through further experiments, it has since been found that film thicknesses greater than 1500 Å are sufficient not to exhibit substrate effects in the TEY data at the Si K-edge, or either the TEY or FLY data at the Si L3,2-edge. A low doped, n-type (100) silicon wafer was used as a crystalline silicon reference for all of the XANES experiments, and the Si3N4 reference sample was an AD ICP CVD film with stoichiometric composition. As the silicon content is increased in the films, the absorption edge shifts to lower energies because of the increase of the Si-Si resonance peak at 1842 eV and reduction of the peak related to Si-N bonding located at 1845.5 eV. The weak Si-O peak at 1848 eV in the crystalline silicon reference spectrum arises from the native oxide layer formed at the silicon surface while any Si-O signal exhibited by the SRSN films originates from oxygen contamination at the surface of the film and should not be taken as an indication of Si-O bonding within the bulk of these films. Figure 4 compares the silicon L3,2-edge spectra for PECVD and ICP CVD AD films. Both sets of films follow similar trends, with the Si-N resonance peak ranging between 103.8 to 104.5 eV as it shifts to lower energies and broadens at higher excess silicon concentrations. However, the PECVD films have a well-defined Si-Si absorption edge at 99.7 eV, which is absent in the ICP CVD-deposited films. The prominence of the absorption edge in PECVD films could be attributed to a difference in the Si-nc structure or the generation of a greater number of nucleation sites for Si-nc formation resulting from the dissociation of hydrogen from the NH3 process gas. Unfortunately, the ECR PECVD films were too thin to avoid a large background signal from the silicon substrate at these energies, and so they have not been included in any of the Si L3,2-edge comparisons.


Effect of thermal treatment on the growth, structure and luminescence of nitride-passivated silicon nanoclusters.

Wilson PR, Roschuk T, Dunn K, Normand EN, Chelomentsev E, Zalloum OH, Wojcik J, Mascher P - Nanoscale Res Lett (2011)

TEY-XANES spectra for (a) PECVD, (b) ECR PECVD, and (c) ICP CVD AD films at the Si K-edge. A, B, and C indicate the peak positions for Si-Si, Si-N, and Si-O resonances, respectively. The percentages in the legend refer to the excess silicon content of the SRSN films.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211220&req=5

Figure 3: TEY-XANES spectra for (a) PECVD, (b) ECR PECVD, and (c) ICP CVD AD films at the Si K-edge. A, B, and C indicate the peak positions for Si-Si, Si-N, and Si-O resonances, respectively. The percentages in the legend refer to the excess silicon content of the SRSN films.
Mentions: The electronic structure was probed through X-ray absorption near edge structure experiments at the silicon K- and L3,2-edges, where differences in structure within the films can be identified by shifts in their spectral features [25-29]. The XANES measurements performed at the silicon K-edge for AD films from each system are shown in Figure 3, which reveal common trends in the Si-nc structure. The spectra of the ICP CVD films were measured from 2-μm-thick films, much larger than the information depth at either absorption edge [30], to ensure that the substrate would not contribute to the TEY or FLY. However, through further experiments, it has since been found that film thicknesses greater than 1500 Å are sufficient not to exhibit substrate effects in the TEY data at the Si K-edge, or either the TEY or FLY data at the Si L3,2-edge. A low doped, n-type (100) silicon wafer was used as a crystalline silicon reference for all of the XANES experiments, and the Si3N4 reference sample was an AD ICP CVD film with stoichiometric composition. As the silicon content is increased in the films, the absorption edge shifts to lower energies because of the increase of the Si-Si resonance peak at 1842 eV and reduction of the peak related to Si-N bonding located at 1845.5 eV. The weak Si-O peak at 1848 eV in the crystalline silicon reference spectrum arises from the native oxide layer formed at the silicon surface while any Si-O signal exhibited by the SRSN films originates from oxygen contamination at the surface of the film and should not be taken as an indication of Si-O bonding within the bulk of these films. Figure 4 compares the silicon L3,2-edge spectra for PECVD and ICP CVD AD films. Both sets of films follow similar trends, with the Si-N resonance peak ranging between 103.8 to 104.5 eV as it shifts to lower energies and broadens at higher excess silicon concentrations. However, the PECVD films have a well-defined Si-Si absorption edge at 99.7 eV, which is absent in the ICP CVD-deposited films. The prominence of the absorption edge in PECVD films could be attributed to a difference in the Si-nc structure or the generation of a greater number of nucleation sites for Si-nc formation resulting from the dissociation of hydrogen from the NH3 process gas. Unfortunately, the ECR PECVD films were too thin to avoid a large background signal from the silicon substrate at these energies, and so they have not been included in any of the Si L3,2-edge comparisons.

Bottom Line: Silicon nanoclusters (Si-ncs) embedded in silicon nitride films have been studied to determine the effects that deposition and processing parameters have on their growth, luminescent properties, and electronic structure.The emission energy was highly dependent on the film composition and changed only slightly with annealing temperature and time, which primarily affected the emission intensity.The PL spectra from films annealed for duration of times ranging from 2 s to 2 h at 600 and 800°C indicated a fast initial formation and growth of nanoclusters in the first few seconds of annealing followed by a slow, but steady growth as annealing time was further increased.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S4L7, Canada. wilsonpr@mcmaster.ca.

ABSTRACT
Silicon nanoclusters (Si-ncs) embedded in silicon nitride films have been studied to determine the effects that deposition and processing parameters have on their growth, luminescent properties, and electronic structure. Luminescence was observed from Si-ncs formed in silicon-rich silicon nitride films with a broad range of compositions and grown using three different types of chemical vapour deposition systems. Photoluminescence (PL) experiments revealed broad, tunable emissions with peaks ranging from the near-infrared across the full visible spectrum. The emission energy was highly dependent on the film composition and changed only slightly with annealing temperature and time, which primarily affected the emission intensity. The PL spectra from films annealed for duration of times ranging from 2 s to 2 h at 600 and 800°C indicated a fast initial formation and growth of nanoclusters in the first few seconds of annealing followed by a slow, but steady growth as annealing time was further increased. X-ray absorption near edge structure at the Si K- and L3,2-edges exhibited composition-dependent phase separation and structural re-ordering of the Si-ncs and silicon nitride host matrix under different post-deposition annealing conditions and generally supported the trends observed in the PL spectra.

No MeSH data available.


Related in: MedlinePlus