Ultrahigh throughput plasma processing of free standing silicon nanocrystals with lognormal size distribution

Silicon nanocrystals (SiNCs) have unique optical and electronic properties that are advantageous for semiconductor device applications and here their application to solar cell is presented. Free-standing, narrow size distribution SiNCs were synthesized by non-thermal plasma using silicon tetrachloride (SiCl4) successfully. Blended solution of as-produced SiNCs and P3HT, or Poly(3-hexylthiophene-2,5-diyl), was spin-casted to form bulk heterojunction solar cell devices. As the weight fraction of SiNCs increased up to 50 wt%, the short circuit current and the power conversion efficiency dramatically increased, while the open circuit voltage and the fill factor do not change significantly. The improved performance is attributable to increased probability of exciton dissociation at acceptor SiNCs and donor P3HT interface.

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Evolution of pyrophyllite particle sizes during dry grinding

Clay Minerals ◽

10.1180/000985500546774 ◽

2000 ◽

Vol 35 (2) ◽

pp. 423-432 ◽

Cited By ~ 21

Author(s):

P. Uhlík ◽

V. Šucha ◽

D. D. Eberl ◽

L'. Puškelová ◽

M. Čaplovičová

Keyword(s):

Size Distribution ◽

Thickness Distribution ◽

Particle Sizes ◽

Transmission Electron ◽

Lognormal Size Distribution ◽

Dry Grinding ◽

Time And Energy ◽

Grinding Time ◽

Crystallite Thickness ◽

Number Of Particles

AbstractThe Bertaut-Warren-Averbach (BWA) technique and high-resolution transmission electron microscopy (HRTEM) were used to characterize the products of dry-ground pyrophyllite. Mean crystallite thickness and crystallite thickness distributions were measured for each sample using the BWA technique. Mean crystallite thickness decreases during the treatment with respect to grinding time and energy applied per unit mass. The BWA data were checked by HRTEM measurements and good fits were obtained for samples having small mean particle thicknesses. Samples with thicker particles could not be measured properly by HRTEM because the number of particles counted from images is statistically insufficient. The shape of the crystallite and the particle-size distribution were used to determine the mechanism of pyrophyllite particle degradation. Particles initially having a lognormal size distribution are first delaminated randomly, then some are delaminated preferentially, thereby producing polymodal thickness distributions. Finally all particles undergo delamination yielding a lognormal thickness distribution.

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Synthesis and Characterization of III-V Rod Shape Semiconductor Nanocrystals

Materials Science Forum ◽

10.4028/www.scientific.net/msf.494.121 ◽

2005 ◽

Vol 494 ◽

pp. 121-128

Author(s):

J.M. Nedeljković ◽

O.I. Mićić ◽

S.P. Ahrenkiel ◽

A.J. Nozik

Keyword(s):

Size Distribution ◽

Semiconductor Nanocrystals ◽

Synthesis And Characterization ◽

Lateral Growth ◽

Narrow Size Distribution ◽

Free Standing ◽

Quantum Rods ◽

Metallic Catalyst ◽

Strong Confinement

InP and InAs quantum rods were synthesized via the reactions of monodispersed indium droplets with phosphide or arsenide ions, respectively. In these reactions indium droplets, which do not act as a catalyst but rather as a reactant, are completely consumed. For the synthesis of InP and InAs quantum rods with a narrow size distribution, a narrow size distribution of indium particles is required because each indium droplet serves as a template to strictly limit the lateral growth of individual InP or InAs nanocrystals. Free-standing InP (130 Å diameter and 870 Å length) and InAs (180 Å diameter and 745 Å length) quantum rods without residual metallic catalyst at the rod tip were synthesized from the diluted transparent solutions of metallic indium. Both kinds of synthesized nanorods are in the strong confinement regime since the Bohr diameters of InP and InAs are 200 and 700 Å, respectively.

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Anisotropic Strain – Anisotropic Heating Engineering for Silicon Nanocrystals in SiO2

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.156-158.523 ◽

2009 ◽

Vol 156-158 ◽

pp. 523-528 ◽

Cited By ~ 3

Author(s):

I.V. Antonova ◽

D.V. Marin ◽

Vladimir A. Volodin ◽

V.A. Skuratov ◽

J. Jedrzejewski ◽

...

Keyword(s):

Electrical Properties ◽

Size Distribution ◽

Silicon Nanocrystals ◽

Ion Irradiation ◽

Ion Bombardment ◽

High Energy ◽

Optical And Electrical Properties ◽

Anisotropic Strain ◽

Si Nanocrystals ◽

New Si

In the present paper we discuss effects due to high-energy ion bombardment of SiO2 layers with embedded Si nanocrystals (NCs), such as the formation of new Si NCs in such layers, amorphization of previously existing NCs, modification of NC size distribution, and modification of optical and electrical properties of NCs. These effects are identified as resulting from anisotropic strain - anisotropic heating in NCs-SiO2 layers under ion irradiation.

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Sub-lognormal size distribution of hospitals — An agent-based approach and empirical study

2013 Winter Simulations Conference (WSC) ◽

10.1109/wsc.2013.6721529 ◽

2013 ◽

Author(s):

Baojun Gao ◽

Wai Kin Victor Chan

Keyword(s):

Empirical Study ◽

Size Distribution ◽

Agent Based ◽

Lognormal Size Distribution

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Influence of reaction parameters on the photoluminescence properties of free standing functionalized silicon nanocrystals

MRS Proceedings ◽

10.1557/proc-1260-t06-05 ◽

2010 ◽

Vol 1260 ◽

Author(s):

Anoop Gupta ◽

Hartmut Wiggers

Keyword(s):

Optical Properties ◽

Surface Functionalization ◽

Silicon Nanocrystals ◽

Organic Molecules ◽

Surface Passivation ◽

Light Emission ◽

Emission Spectra ◽

Surface Oxidation ◽

Free Standing ◽

The Stability

AbstractWhile silicon nanostructures acquire novel optical properties due to miniaturization, the stability of light emission is severely limited because of exciton trapping due to surface oxidation coming along with the formation of defects. Grafting of organic molecules on a hydrogen-terminated silicon surface via hydrosilylation provides a promising route to stabilize their surface against oxidation. In this communication, we report on the effect of surface passivation on the optical properties of freestanding silicon nanocrystals (Si-NCs). The surface functionalization of hydrogen-terminated Si-NCs with organic molecules was achieved via liquid phase hydrosilylation. We demonstrate that surface functionalization does not preserve the original emission of hydrogen-terminated Si-NCs. It is observed that the emission spectrum of green emitting hydrogen-terminated Si-NCs is red shifted after surface functionalization. We find that the direction of shift does not depend on the type of organic ligands and the reaction conditions, however, the amount of shift can be altered. The factors influencing the shift in the emission spectra of functionalized Si-NCs with respect to hydrogen-terminated samples are discussed.

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Drizzle in Stratiform Boundary Layer Clouds. Part II: Microphysical Aspects

Journal of the Atmospheric Sciences ◽

10.1175/jas3530.1 ◽

2005 ◽

Vol 62 (9) ◽

pp. 3034-3050 ◽

Cited By ~ 114

Author(s):

R. Wood

Keyword(s):

Boundary Layer ◽

Size Distribution ◽

Large Scale ◽

Cloud Droplet ◽

Horizontal Structure ◽

Boundary Layer Clouds ◽

Droplet Concentration ◽

Warm Rain ◽

Lognormal Size Distribution ◽

Accretion Rates

Abstract This is the second of two observational papers examining drizzle in stratiform boundary layer clouds. Part I details the vertical and horizontal structure of cloud and drizzle parameters, including some bulk microphysical variables. In this paper, the focus is on the in situ size-resolved microphysical measurements, particularly of drizzle drops (r > 20 μm). Layer-averaged size distributions of drizzle drops within cloud are shown to be well represented using either a truncated exponential or a truncated lognormal size distribution. The size-resolved microphysical measurements are used to estimate autoconversion and accretion rates by integration of the stochastic collection equation (SCE). These rates are compared with a number of commonly used bulk parameterizations of warm rain formation. While parameterized accretion rates agree well with those derived from the SCE initialized with observed spectra, the autoconversion rates seriously disagree in some cases. These disagreements need to be addressed in order to bolster confidence in large-scale numerical model predictions of the aerosol second indirect effect. Cloud droplet coalescence removal rates and mass and number fall rate relationships used in the bulk microphysical schemes are also compared, revealing some potentially important discrepancies. The relative roles of autoconversion and accretion are estimated by examination of composite profiles from the 12 flights. Autoconversion, although necessary for the production of drizzle drops, is much less important than accretion throughout the lower 80% of the cloud layer in terms of the production of drizzle liquid water. The SCE calculations indicate that the autoconversion rate depends strongly upon the cloud droplet concentration Nd such that a doubling of Nd would lead to a reduction in autoconversion rate of between 2 and 4. Radar reflectivity–precipitation rate (Z–R) relationships suitable for radar use are derived and are shown to be significantly biased in some cases by the undersampling of large (r > 200 μm) drops with the 2D-C probe. A correction based upon the extrapolation to larger sizes using the exponential size distribution changes the Z–R relationship, leading to the conclusion that consideration should be given to sampling issues when examining higher moments of the drop size distribution in drizzling stratiform boundary layer clouds.

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Sensitivity Analysis of the Surface Acoustic Wave Sensor towards Size-Distributed Particulate Matter

Shock and Vibration ◽

10.1155/2020/6665508 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Jian Yang ◽

Jianan Lu ◽

Shanmeng Zhang ◽

Dong Guan

Keyword(s):

Particulate Matter ◽

Acoustic Wave ◽

Frequency Shift ◽

Size Distribution ◽

Surface Acoustic Wave ◽

Saw Sensor ◽

Lognormal Size Distribution ◽

Acoustic Wave Sensor ◽

Distribution Parameters ◽

Relationship Of

To study the sensitivity of the surface acoustic wave (SAW) sensor towards particulate matter (PM), an analytic model has been built based on single particle perturbation theory of full size range and the lognormal size distribution of the PM. The sensitivity of the frequency shift to 1 nanogram of PM has been calculated. The model shows that the frequency shift is a result of the competition between the negative perturbation by mass loading and the positive perturbation by elastic coupling, determined by particle size distribution parameters, material, and SAW frequency. To verify the model, the relationship of the frequency shift of a 315 MHz SAW to the concentration of aerosols generated by two kinds of powders of different sizes was measured. The experiment is in agreement with the model: the sensor has shown negative sensitivity towards aerosols generated by the finer particles of 1 μm, 3 μm polytetrafluoroethylene (PTFE), and A1 Arizona dust and positive sensitivity towards aerosols generated by the coarser particles of 10 μm PTFE and A4 Arizona dust; and the negative sensitivity is about 1 order higher than the positive.

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