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

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.

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.

Visible Light Emitting Diode Employing Electrochemically Anodized Nanocrystalline Silicon Thin Film

1996 ◽  
Vol 452 ◽  
Author(s):  
T. Toyama ◽  
T. Yamamoto ◽  
T. Matsui ◽  
H. Okamoto
Keyword(s):  
Thin Film ◽  
Light Emitting Diode ◽  
Light Output ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
Rf Plasma ◽  
Silicon Thin Film ◽  
Light Emitting ◽  
Plasma Chemical Vapor Deposition ◽  
Boron Doped

AbstractVisible electroluminescence (EL) has been achieved on the entirely solid state thin film light emitting diode (TFLED) employing electrochemically anodized nanocrystalline Si (nc-Si) as a light emitting active layer. The TFLED consisting of p-type nc-Si, and intrinsic and n-type amorphous layers was fabricated on a SnO2-coated glass substrate. The nc-Si was formed in HF aqueous solution from boron doped microcrystalline Si (μc-Si) deposited by rf plasma chemical vapor deposition (CVD). The TFLED exhibits clear rectification with a forward threshold voltage of about 1.5 V, whereas visible EL emission is observed upon applying reverse bias voltages. The diode ideality factor is more than 2, and the light output increases with the square of the diode current. The EL emission color is orange-red and the spectral peak energy is 1.8 eV.

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.

Nanocrystalline silicon as the light emitting material of a field emission display device

2008 ◽  
Vol 19 (22) ◽  
pp. 225202 ◽  
Author(s):  
A Biaggi-Labiosa ◽  
F Solá ◽  
O Resto ◽  
L F Fonseca ◽  
A González-Berríos ◽  
...  
Keyword(s):  
Field Emission ◽  
Nanocrystalline Silicon ◽  
Display Device ◽  
Field Emission Display ◽  
Light Emitting

Origin of the multi-exponential decay dynamics in light-emitting silicon nanocrystals

2004 ◽  
Vol 832 ◽  
Author(s):  
Cécile Reynaud ◽  
Olivier Guillois ◽  
Nathalie Herlin-Boime ◽  
Gilles Ledoux ◽  
Friedrich Huisken
Keyword(s):  
Exponential Decay ◽  
Silicon Nanocrystals ◽  
Gas Flow ◽  
Flow Reactor ◽  
Particle Density ◽  
Nanocrystalline Silicon ◽  
Light Emitting ◽  
Stretched Exponential ◽  
Film Density ◽  
Exponential Law

ABSTRACTLight-emitting silicon nanocrystals (nc-Si) have attracted much interest due to their importance for optoelectronic devices. Electron hole recombination in a quantum confined system is generally considered as the theoretical frame explaining the photoluminescence (PL) origin. However, there is still a living debate, in particular regarding the PL decay dynamics. The decay is not single exponential and decay curves described by a stretched exponential law were systematically reported for all types of nanocrystalline silicon. The origin of this multi-exponential decay is often attributed to migration effects of the excitons between nanocrystals. In contrast to these approaches, the absence of carrier hopping has been demonstrated experimentally in porous silicon. In order to elucidate this question, specific samples were prepared, consisting in deposits made from gas phase grown silicon nanocrystals with different particle density. The nanoparticles were synthesized by laser pyrolysis of silane in a gas flow reactor, extracted as a supersonic beam, size-selected, and deposited downstream as films of variable densities by changing the deposition time. The nanoparticle number densities were determined by atomic force microscopy. Time-resolved photoluminescence measurements on these films were carried out as a function of the film density and at different PL wavelengths. The reported results showed photoluminescence properties independent of the film density. Even in the very low density film (∼4*109 particles/cm2) where nanoparticles are completely isolated from each other, the decay kinetics corresponds to a multi-exponential law. This means that exciton migration alone cannot explain the stretched exponential decay. Its origin must be linked to an intrinsic characteristic of the nc-Si particle. In this paper, the experimental results are described in more details and compared to the theoretical predictions available in the frame of the quantum confinement model. Then, the possible origins of the multi-exponential character of the decay dynamics is discussed, and the particular properties of the PL in indirect band-gap semiconductors emphasized.

The mean crystallite size within a hydrogenated nanocrystalline silicon based photovoltaic solar cell and its role in determining the corresponding crystalline volume fraction

2014 ◽  
Vol 92 (7/8) ◽  
pp. 857-861 ◽  
Author(s):  
K.J. Schmidt ◽  
Y. Lin ◽  
M. Beaudoin ◽  
G. Xia ◽  
S.K. O’Leary ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Volume Fraction ◽  
Nanocrystalline Silicon ◽  
Crystalline Volume Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Photovoltaic Solar Cell ◽  
Crystallite Sizes ◽  
The Mean ◽  
Silicon Based

We examine the dependence of the crystalline volume fraction on the mean crystallite size for hydrogenated nanocrystalline silicon based photovoltaic solar cells; this work builds upon an earlier study by Schmidt et al. (Mater. Res. Soc. Symp. Proc. 1536 (2013)). For each photovoltaic solar cell considered, the X-ray diffraction and Raman spectra are measured. Through the application of Scherrer’s equation, the X-ray diffraction results are used to determine the corresponding mean crystallite sizes. Through peak decomposition, the Raman results are used to estimate the corresponding crystalline volume fraction. Plotting the crystalline volume fraction as a function of the mean crystallite size, it is found that larger mean crystallite sizes tend to favor reduced crystalline volume fractions. The ability to randomly pack smaller crystallites with a greater packing fraction than their larger counterparts was suggested as a possible explanation for this observation.

First-Principles Calculation of the Optical Properties of Nanocrystalline Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
Masahiko Hirao
Keyword(s):  
Optical Properties ◽  
Crystallite Size ◽  
First Principles ◽  
Density Functional ◽  
Energy Gap ◽  
Nanocrystalline Silicon ◽  
First Principles Calculation ◽  
Nonradiative Recombination ◽  
Dangling Bonds ◽  
Hydrogen Atoms

ABSTRACTThe electronic structure and optical properties of nanocrystalline silicon were calculated by the first-principles density functional pseudopotential approach. The calculated energy-gap upshift from the bulk-Si value is nearly proportional to the reciprocal of the crystallite size. Dipole transitions across the gap are weakly allowed and the transition elements decrease rapidly with increases in the crystallite size. The apparent lifetime, the time over which the intensity decreases to 1/e of the initial value, decreases sharply from milliseconds to microseconds within a certain temperature range. The effect of dehydrogenation and the structural stability were investigated using an ab initio molecular dynamics technique. When some of the surface hydrogen atoms are removed, subsequent lattice relaxation eliminates dangling bonds. Further dehydrogenation creates mid-gap states due to surface dangling bonds, which act as nonradiative recombination centers. The calculated results are compared with observations of porous Si.

Nanocrystalline Silicon Thin Film Transistors on Optically Clear Polymer Foil Substrates

2005 ◽  
Vol 870 ◽  
Author(s):  
Alex Kattamis ◽  
I-Chun Cheng ◽  
Ke Long ◽  
James C. Sturm ◽  
Sigurd Wagner
Keyword(s):  
Nanocrystalline Silicon ◽  
Organic Light Emitting Diodes ◽  
Silicon Thin Film ◽  
Polymer Substrates ◽  
Thermally Stable Polymers ◽  
Light Emitting ◽  
Active Layers ◽  
Organic Light ◽  
Direct Substitution ◽  
Polymer Foils

AbstractWe have fabricated TFTs of nanocrystalline silicon (nc-Si) at 150°C on clear polymer substrates (coefficients of thermal expansion, α∼45 to 55ppm/K), on Kapton® 200E (α=17ppm/K), and on Corning 1737 glass (α=3ppm//K) for comparison. Because thermally stable polymers, such as Kapton® 200E polyimide, have glass transition temperatures as high as 325°C, they are candidates for direct substitution of display glass. The stresses developed in the substrate and device layers, due to à, are reduced by decreasing the thickness of the active layers, by cutting the layers into islands separated by exposed substrate, and by designing stresses, via plasma conditions, into the SiNx passivating layers. By using these three techniques we have made nc-Si TFTs on high Tg, and high α, clear polymer foils with electron mobilities of up to 18cm2/Vs. When integrated with bottom-emitting organic light emitting diodes, such devices will allow for a 10x reduction in pixel TFT areas, compared to TFTs of amorphous silicon.

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