Photoluminescence from Nanocrystalline Silicon Prepared by Plasma CVD and Oxidation

1993 ◽  
Vol 298 ◽  
Author(s):  
S. Veprek ◽  
M. Rückschloβ ◽  
B. Landkammer ◽  
O. Ambacher
Keyword(s):  
Crystallite Size ◽  
Size Dependence ◽  
Theoretical Models ◽  
Nanocrystalline Silicon ◽  
Photoluminescence Intensity ◽  
Plasma Cvd ◽  
Light Emitting ◽  
Silicon Technology ◽  
Dry Processing ◽  
Peak Energy

AbstractLight emitting nanocrystalline silicon has been prepared by a completely dry processing which uses standard silicon technology. This enables us to prepare compact films on various substrates and to control the crystallite size. Dependence of the photoluminescence intensity and its peak energy on the crystallite size is reported and compared with current theoretical models.

Light emitting nanocrystalline silicon prepared by dry processing: The effect of crystallite size

1993 ◽  
Vol 63 (11) ◽  
pp. 1474-1476 ◽  
Author(s):  
M. Rückschloss ◽  
B. Landkammer ◽  
S. Vepřek
Keyword(s):  
Crystallite Size ◽  
Nanocrystalline Silicon ◽  
Light Emitting ◽  
Dry Processing

Optical Transitions in Light-Emitting Nanocrystalline Silicon Thin Films

1999 ◽  
Vol 557 ◽  
Author(s):  
T. Toyama ◽  
Y. Kotani ◽  
A. Shimode ◽  
S. Abo ◽  
H. Okamoto
Keyword(s):  
Thin Films ◽  
Crystal Size ◽  
Nanocrystalline Silicon ◽  
Optical Transitions ◽  
Direct Transition ◽  
Light Emitting ◽  
Silicon Thin Films ◽  
Peak Energy ◽  
The Mean ◽  
Nanocrystalline Si

AbstractOptical transitions in nanocrystalline Si (nc-Si) thin films with different mean crystal sizes ranging from < 2 nm to ~3 nm have been studied by electroreflectance (ER) spectroscopy. At 293 K, ER signals are observed at 1.20-1.37 eV to be corresponding to fundamental gap in bulk crystalline Si. With a decrease in the mean crystal sizes of nc-Si, the transition energy of the fundamental gap is increased and the ER signal is intensified. The bandgap widening would be due to quantum confinement (QC) in nc-Si, and the increased signal indicates appearance of direct transition nature. The ER signals are also observed at 2.2 eV and at E1 (E0’) direct gap of 3.1-3.4 eV, while photoluminescence (PL) peak energies are located at 1.65-1.75 eV and at 2.3 eV. With the reduced mean crystal size, the 1.7-eV PL peak energy is also increased, suggesting that QC is also responsible for the increased PL peak energy.

Optical Spectroscopy and Composition of InGaN

1999 ◽  
Vol 595 ◽  
Author(s):  
K.P. O'Donnell ◽  
R.W. Martin ◽  
M.E. White ◽  
K. Jacobs ◽  
W. Van der Stricht ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Stokes Shift ◽  
Theoretical Models ◽  
Indium Content ◽  
Light Emitting ◽  
X Ray ◽  
Light Emitting Devices ◽  
Peak Energy ◽  
X Ray Absorption ◽  
Limiting Value

AbstractCommercial light emitting devices (LEDs) containing InGaN layers offer unrivalled performance in the violet (∼400 nm), blue (∼450 nm) and green (∼520 nm) spectral regions. Nichia Chemicals Company has also produced amber InGaN LEDs with peak output near 590 nm. Here, we predict, on purely theoretical grounds, a surprisingly high limiting value of 1020 nm (peak) for InGaN intrinsic emission. We partly confirm this prediction by spectroscopic measurements of samples with photoluminescence (PL) peaks between 370 nm and 980 nm. In addition, we have measured the indium content of a range of light-emitting layers, using Rutherford Backscattering Spectrometry (RBS), Extended X-Ray Absorption Fine Structure (EXAFS) and Energy Dispersive X-Ray Analysis (EDX). The PL peak energy is found to depend linearly on the indium fraction: violet-emitting layers have an indium content of ∼8%, blue layers ∼16% and green layers ∼25%. A linear extrapolation to the limit set by the Stokes' shift prediction, mentioned earlier, yields a limiting indium concentration of only ∼52%. The profound impact of these results on future extensions of nitride technology and current theoretical models of InGaN is briefly discussed.

Giant Anisotropy of Conductivity in Hydrogenated Nanocrystalline Silicon Thin Films

1998 ◽  
Vol 536 ◽  
Author(s):  
A. B. Pevtsov ◽  
N. A. Feoktistov ◽  
V. G. Golubev
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Percolation Theory ◽  
Nanocrystalline Silicon ◽  
Spatial Light Modulators ◽  
Light Emitting ◽  
Light Modulators ◽  
Silicon Thin Films ◽  
Longitudinal Conductivity ◽  
Transverse Conductivity

AbstractThin (<1000 Å) hydrogenated nanocrystalline silicon films are widely used in solar cells, light emitting diodes, and spatial light modulators. In this work the conductivity of doped and undoped amorphous-nanocrystalline silicon thin films is studied as a function of film thickness: a giant anisotropy of conductivity is established. The longitudinal conductivity decreases dramatically (by a factor of 109 − 1010) as the layer thickness is reduced from 1500 Å to 200 Å, while the transverse conductivity remains close to that of a doped a- Si:H. The data obtained are interpreted in terms of the percolation theory.

Material and optical properties of GaAs grown on (001) Ge/Si pseudo-substrate

2004 ◽  
Vol 809 ◽  
Author(s):  
Yves Chriqui ◽  
Ludovic Largeau ◽  
Gilles Patriarche ◽  
Guillaume Saint-Girons ◽  
Sophie Bouchoule ◽  
...  
Keyword(s):  
Optical Properties ◽  
Dislocation Density ◽  
High Speed ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Lattice Parameter ◽  
Photoluminescence Intensity ◽  
High Quality ◽  
Light Emitting ◽  
Thermal Expansion Coefficients

ABSTRACTOne of the major challenges during recent years was to achieve the compatibility of III-V semiconductor epitaxy on silicon substrates to combine opto-electronics with high speed circuit technology. However, the growth of high quality epitaxial GaAs on Si is not straightforward due to the intrinsic differences in lattice parameters and thermal expansion coefficients of the two materials. Moreover, antiphase boundaries (APBs) appear that are disadvantageous for the fabrication of light emitting devices. Recently the successful fabrication of high quality germanium layers on exact (001) Si by chemical vapor deposition (CVD) was reported. Due to the germanium seed layer the lattice parameter is matched to the one of GaAs providing for excellent conditions for the subsequent GaAs growth. We have studied the material morphology of GaAs grown on Ge/Si PS using atomic layer epitaxy (ALE) at the interface between Ge and GaAs. We present results on the reduction of APBs and dislocation density on (001) Ge/Si PS when ALE is applied. The ALE allows the reduction of the residual dislocation density in the GaAs layers to 105 cm−2 (one order of magnitude as compared to the dislocation density of the Ge/Si PS). The optical properties are improved (ie. increased photoluminescence intensity). Using ALE, light emitting diodes based on strained InGaAs/GaAs quantum well as well as of In(Ga)As quantum dots on an exactly oriented (001) Ge/Si pseudo-substrate were fabricated and characterized.

On crystallite size dependence of phase stability of nanocrystalline TiO2

2003 ◽  
Vol 94 (7) ◽  
pp. 4577-4582 ◽  
Author(s):  
T. B. Ghosh ◽  
Sampa Dhabal ◽  
A. K. Datta
Keyword(s):  
Crystallite Size ◽  
Phase Stability ◽  
Size Dependence ◽  
Nanocrystalline Tio2

scholarly journals First measurement of the 2.4 MeV and 2.9 MeV 6He three-cluster resonant states via the 3H(4He, pα)2n four-body reaction

2014 ◽  
Vol 29 (19) ◽  
pp. 1450105 ◽  
Author(s):  
Giuseppe Mandaglio ◽  
Orest Povoroznyk ◽  
Olga K. Gorpinich ◽  
Olexiy O. Jachmenjov ◽  
Antonio Anastasi ◽  
...  
Keyword(s):  
Excited States ◽  
Beam Energy ◽  
Threshold Energy ◽  
Theoretical Models ◽  
Light Nuclei ◽  
Energy Spectra ◽  
Excitation Energies ◽  
Resonant States ◽  
Peak Energy ◽  
Coincidence Spectra

Two new low-lying 6 He levels at excitation energies of about 2.4 MeV and 2.9 MeV were observed in the experimental investigation of the p-α coincidence spectra obtained by the 3 H (4 He , p α)2 n four-body reaction at E4 He beam energy of 27.2 MeV. The relevant E* peak energy and Γ energy width spectroscopic parameters for such 6 He * excited states decaying into the α+ n+n channel were obtained by analyzing the bidimensional (E p , Eα) energy spectra. The present new result of two low-lying 6 He * excited states above the 4 He +2 n threshold energy of 0.974 MeV is important for the investigation of the nuclear structure of neutron-rich light nuclei and also as a basic test for theoretical models in the study of the three-cluster resonance feature of 6 He .

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