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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.


Related in: MedlinePlus

PL spectra for films annealed for 60 min in a quartz tube furnace. Shown are an ICP CVD film (Siex < 1%) annealed in (a) N2, (b) N2 + 5% H2 and a PECVD film (Siex = 3%) annealed in (c) N2, and (d) N2 + 5% H2.
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Figure 2: PL spectra for films annealed for 60 min in a quartz tube furnace. Shown are an ICP CVD film (Siex < 1%) annealed in (a) N2, (b) N2 + 5% H2 and a PECVD film (Siex = 3%) annealed in (c) N2, and (d) N2 + 5% H2.

Mentions: The effects of annealing a PECVD film with moderately high excess silicon content and an ICP CVD film with low excess silicon content using different ambient gases are compared in Figure 2. In general, the emission spectra for samples with higher excess silicon content tend to red-shift slightly as the annealing temperature is increased, whereas lower excess silicon content samples exhibit a slight blue-shift. In samples containing intermediate levels of excess silicon content, the PL peaks have also been observed to blue-shift relative to the AD spectra at low temperatures and red-shift as the annealing temperature is further increased. There appear to be at least two competing mechanisms in the Si-nc growth dynamics related to the growth of existing Si-ncs due to diffusion of silicon atoms in the film and the formation and subsequent growth of new Si-ncs at nucleation sites. The red-shifting resulting from Si-nc growth is much smaller than that observed in SRSO films, but this can be explained by the more diffusion-inhibiting structure of the silicon nitride matrix relative to the silicon oxide matrix [24]. It is also possible that energy may be transferred between smaller and larger Si-ncs, which affects the observed PL spectra. In all of the samples, the most intense emission consistently occurred when annealing was performed at 800°C or below, with peak intensities being observed at lower temperatures for higher silicon content samples. The reason for the decay in PL intensity at higher temperatures is unknown at this time since (a) Si-ncs are still present in TEM images (not shown) and X-ray absorption spectra of these films and (b) the Si-ncs have not grown beyond the quantum confinement regime because of the inhibitive nature of the nitride matrix. As the decay in luminescence does not appear to relate to structural changes in the Si-nc, this suggests that it results from changes in the host nitride matrix or with the interface passivation. Such effects could arise from the strain induced on the Si-ncs by the nitride matrix or a re-ordering of the nitride matrix structure at the Si-nc interface such that non-radiative recombination pathways become available. However, further investigation is required to accurately attribute the source of this phenomenon.


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)

PL spectra for films annealed for 60 min in a quartz tube furnace. Shown are an ICP CVD film (Siex < 1%) annealed in (a) N2, (b) N2 + 5% H2 and a PECVD film (Siex = 3%) annealed in (c) N2, and (d) N2 + 5% H2.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: PL spectra for films annealed for 60 min in a quartz tube furnace. Shown are an ICP CVD film (Siex < 1%) annealed in (a) N2, (b) N2 + 5% H2 and a PECVD film (Siex = 3%) annealed in (c) N2, and (d) N2 + 5% H2.
Mentions: The effects of annealing a PECVD film with moderately high excess silicon content and an ICP CVD film with low excess silicon content using different ambient gases are compared in Figure 2. In general, the emission spectra for samples with higher excess silicon content tend to red-shift slightly as the annealing temperature is increased, whereas lower excess silicon content samples exhibit a slight blue-shift. In samples containing intermediate levels of excess silicon content, the PL peaks have also been observed to blue-shift relative to the AD spectra at low temperatures and red-shift as the annealing temperature is further increased. There appear to be at least two competing mechanisms in the Si-nc growth dynamics related to the growth of existing Si-ncs due to diffusion of silicon atoms in the film and the formation and subsequent growth of new Si-ncs at nucleation sites. The red-shifting resulting from Si-nc growth is much smaller than that observed in SRSO films, but this can be explained by the more diffusion-inhibiting structure of the silicon nitride matrix relative to the silicon oxide matrix [24]. It is also possible that energy may be transferred between smaller and larger Si-ncs, which affects the observed PL spectra. In all of the samples, the most intense emission consistently occurred when annealing was performed at 800°C or below, with peak intensities being observed at lower temperatures for higher silicon content samples. The reason for the decay in PL intensity at higher temperatures is unknown at this time since (a) Si-ncs are still present in TEM images (not shown) and X-ray absorption spectra of these films and (b) the Si-ncs have not grown beyond the quantum confinement regime because of the inhibitive nature of the nitride matrix. As the decay in luminescence does not appear to relate to structural changes in the Si-nc, this suggests that it results from changes in the host nitride matrix or with the interface passivation. Such effects could arise from the strain induced on the Si-ncs by the nitride matrix or a re-ordering of the nitride matrix structure at the Si-nc interface such that non-radiative recombination pathways become available. However, further investigation is required to accurately attribute the source of this phenomenon.

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