Strained Interface Defects in Silicon Nanocrystals

Lee, Benjamin G.; Hiller, Daniel; Luo, Jun-Wei; Semonin, Octavi E.; Beard, Matthew C.; Zacharias, Margit; Stradins, Paul

doi:10.1002/adfm.201200572

Cited by 66 publications

(52 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Earlier suggestions for such centers include Si=O double bonds, 30,31 Si-O-Si bridge bonds, 2,32-34 and strained bonds/geometries. 2,34,35 The former seem to be rather unstable. The latter, in view of the present results, may also be associated with inner regions of the NC.…”

Section: Resultsmentioning

confidence: 98%

Stress state of embedded Si nanocrystals

Kleovoulou

Kelires

2013

Phys. Rev. B

View full text Add to dashboard Cite

Monte Carlo simulations shed light on the stress state of Si nanocrystals embedded in amorphous silica, unraveling and explaining its nature and origins. This is achieved by generating detailed stress maps and by calculating the stress profile as a function of size and distance between the nanocrystals. For normal oxide matrix densities, the average stress in the nanocrystal core is found to be compressive, reaching values of 3-4 GPa, in excellent agreement with experimental measurements. It drastically declines at the interface, despite the existence of several highly strained geometries. Tensile conditions prevail in nanocrystals embedded in densified silica matrices. The nanocomposites are shown to be stable, at close interdot distances, against segregation and phase separation.

show abstract

Section: Resultsmentioning

confidence: 98%

Stress state of embedded Si nanocrystals

Kleovoulou

Kelires

2013

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…The PL decays exponentially, with the time constant slightly changes from 17 to 21 ns as the temperature is decreased from 300 to 77 K. This very short lifetime is in agreement with the electric-dipole allowed 4f–5d transition rate of Ce 3+ . Since non-radiative centers are frozen at low temperatures, we attribute the decrease of the PL intensity and the decay time to the energy transfer to defect centers by non-radiative recombination processes38.…”

Section: Resultsmentioning

confidence: 99%

A novel violet/blue light-emitting device based on Ce2Si2O7

Wang

et al. 2015

Sci Rep

View full text Add to dashboard Cite

Rare-earth silicates are highly efficient materials for silicon-based light sources. Here we report a novel light-emitting device based on Ce2Si2O7. Intense violet/blue electroluminescence was observed, with a turn-on voltage of about 13 V. The violet/blue emission is attributed to 4f–5d transitions of the Ce3+ ions in Ce2Si2O7, which are formed by interfacial reaction of CeO2 and Si. Electroluminescence and photoluminescence mechanisms of the Ce2Si2O7 light-emitting device are also discussed.

show abstract

“…In third generation silicon solar cells with a triple tandem structure, the top cell should have the highest band gap ($2.0 eV) and the two subsequent cells need to have sequentially lower band gaps in order to enable efficient absorption of the solar spectrum. 7 Among those, nanoscaled superlattice structures with alternate Si-rich layers and Si 3 N 4 /SiO 2 /SiC dielectric layers have attracted substantial attention as they provide superior control over the growth of Si-ncs 2 which, however, proceeds essentially through high temperature post-deposition annealing at $1100 C. [13][14][15][16] On annealing, solid-phase crystallization in the Si-rich layer leads to the formation of Si-ncs and their size-evolution is constrained by the thickness of the Si-rich sub-layer within the dielectric barriers on both sides. In implementing such a scheme, superior control over the size of the Si-ncs and their distribution are prerequisites.…”

Section: Introductionmentioning

confidence: 99%

Superior optical response of size-controlled silicon nano-crystals in a-Si:H/nc-Si:H superlattice films for multi-junction solar cells

Kar

Das

2015

RSC Adv.

View full text Add to dashboard Cite

In order to facilitate widening in optical band gaps utilizing quantum size-effects in silicon nano-crystals (Si-ncs) of a few nanometers in dimension, self-assembled Si-ncs embedded in an a-Si matrix were grown within a-Si:H/nc-Si:H superlattice (SL) thin films produced by alternating sub-layers of a-Si:H and nc-Si:H from (SiH 4 + H 2 )-plasma in PE-CVD at 180 C, without post-deposition annealing. The growth of Si-ncs extending all through the nc-Si:H sub-layer thickness is terminated by the alternate deposition of an a-Si:H barrier layer during each cycle and the average size of the Si-ncs with a narrow size distribution is tuned by controlling each nc-Si:H sub-layer thickness. Significantly high-density tiny Si-ncs are grown even within an ultra-thin ($3 nm) nc-Si:H sub-layer and that has been made possible via an ingenious approach, by utilizing the underneath of an a-Si:H sub-layer as the virtual incubation layer at a very specifically chosen parametric condition, during each cycle of periodic deposition. On systematic thinning of the nc-S:H active layer within 8-3 nm, a remarkable increase in optical absorption at near-UV photon energies along with simultaneous optical band gap widening within 1.89-2.04 eV demonstrate that the quantum size-effect in Si-ncs plays a key role. Subsequent lowering in the defect states identifies the nc-Si:H/a-Si:H SL-films as a superior material for use in devices, including as i-layers in triple-junction all-silicon solar cells.

show abstract

Strained Interface Defects in Silicon Nanocrystals

Cited by 66 publications

References 44 publications

Stress state of embedded Si nanocrystals

Stress state of embedded Si nanocrystals

A novel violet/blue light-emitting device based on Ce2Si2O7

Superior optical response of size-controlled silicon nano-crystals in a-Si:H/nc-Si:H superlattice films for multi-junction solar cells

Contact Info

Product

Resources

About