A Propos de la Création de Photoporteurs à Partir d'Excitons dans CdS

1971 ◽  
Vol 49 (14) ◽  
pp. 1967-1970 ◽  
Author(s):  
A. Coret ◽  
H. L. Malm
Keyword(s):  
Light Intensity ◽  
Photoconductivity Spectrum ◽  
Free Carriers ◽  
Recombination Processes ◽  
The Creation

According to the variation of the photoconductivity spectrum of CdS with light intensity it appears that excitons do not play a role in the recombination processes of photocarriers. Excitons first dissociate and give free carriers. The existence of maxima of photocurrent is related to the creation of photocarriers near the surface.

Picosecond Photomodulation Study of Nanocrystalline Hydrogenated Silicon

1989 ◽  
Vol 164 ◽  
Author(s):  
M. Wraback ◽  
Lingrong Chen ◽  
J. Tauc ◽  
Z. Vardeny
Keyword(s):  
Light Intensity ◽  
Amorphous Phase ◽  
Temporal Resolution ◽  
Time Domain ◽  
Hydrogenated Silicon ◽  
High Illumination ◽  
Recombination Processes

AbstractWe have extended our photomodulation studies of nc-Si:H to the picosecond time domain. We measured the decays of photoinduced reflectivity with 100fs temporal resolution as a function of light intensity. Comparison with the data obtained on a-Si:H and c-Si indicates that ultrafast trapping and recombination processes are mainly the properties of the amorphous phase. It has also been observed that nc-Si:H is unstable under high illumination.

SEMICONDUCTOR EXCITON OPTICAL BISTABILITY AS INFLUENCED BY FREE CARRIERS

1993 ◽  
Vol 07 (28) ◽  
pp. 4815-4825
Author(s):  
NGUYEN BA AN ◽  
NGUYEN TRUNG DAN ◽  
HOANG XUAN NGUYEN
Keyword(s):  
Light Intensity ◽  
Hysteresis Loop ◽  
Phase Diagrams ◽  
Optical Bistability ◽  
Exciton Density ◽  
Free Carriers ◽  
Loop Size

Exciton density in an optically excited semiconductor is calculated as a function of pumping light intensity. In a certain domain in the detuning-intensity plane there may appear bistability of exciton density which is shown considerably influenced by the presence of free carriers. The carrier-induced effect manifests itself in the modification of phase diagrams leading to changes of the hysteresis loop size in both intensity-controlled and frequency-controlled bistabilities.

Light Intensity Exponents as Sensitive Tools for the Detection of Impurities in a-Si:H

2000 ◽  
Vol 609 ◽  
Author(s):  
L. F. Fonseca ◽  
S.Z. Weisz ◽  
P. Alpuim ◽  
V. Chu ◽  
J.P. Conde ◽  
...  
Keyword(s):  
Light Intensity ◽  
Temperature Dependence ◽  
Computer Simulations ◽  
Dominant Factor ◽  
State Distribution ◽  
Capture Coefficient ◽  
Yield Information ◽  
Recombination Processes ◽  
Minority Carriers ◽  
Forbidden Gap

ABSTRACTWe have shown recently that the temperature dependence of the phototransport properties can yield information regarding the state distribution in the forbidden gap of semiconductors. Of these properties the light intensity exponents of both, the majority carriers, γe, and the minority carriers, γh, were found to be very sensitive to the details of this distribution. In particular, noting that sub 1/2 values of the exponents are very unusual we have studied their origin in some a-Si:H materials. Finding experimentally such sub 1/2 values of γh and running computer simulations of the recombination processes in a-Si:H led us to the conclusion that these low values are due to acceptor-like centers which have a relatively high capture coefficient for the holes. We attribute these centers to the unintentional oxygen doping in a-Si:H. We will show that the oxygen presence, usually ignored in the discussions of the phototransport properties of a-Si:H, appears to be, in many cases, the dominant factor in the properties of “intrinsic” a-Si:H.

Contribution of second‐harmonic generation to the creation of free carriers in CdTe single crystals

1990 ◽  
Vol 56 (17) ◽  
pp. 1632-1634 ◽  
Author(s):  
Mark S. Petrovic ◽  
Andrzej Suchocki ◽  
Richard C. Powell ◽  
Gene Cantwell ◽  
Jeff Aldridge
Keyword(s):  
Second Harmonic Generation ◽  
Single Crystals ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Free Carriers ◽  
The Creation

Raman Investigation of the Effect of Metal Impurities at Gettering Sites on Phonon and Electron Related Properties of 4H-SiC n-n+ Junctions

2008 ◽  
Vol 600-603 ◽  
pp. 465-468
Author(s):  
Michel Kazan ◽  
Laurent Ottaviani ◽  
Pierre M. Masri
Keyword(s):  
Charge Carrier ◽  
Ion Implantation ◽  
Room Temperature ◽  
Free Carriers ◽  
Metal Impurities ◽  
Recombination Processes ◽  
Fano Interference ◽  
Carrier Traps ◽  
Helium Implantation ◽  
Gold Diffusion

We report on the application of introducing gettering sites as an approach to control some phonons and charge carrier related properties in 4H-SiC epilayer. Helium implantation (at room temperature or 750°C) was first carried out, followed by a proper annealing and gold diffusion, in order to check the gettering efficiency. Raman measurements showed the presence of the desired defect, introduced by ion implantation at RT. The shift of the Fano interference allowed us to calculate the free carriers’ density in each sample. The lowest value was found for the sample implanted at RT. The gettering sites can act as majority carrier traps and reducers of recombination processes, which can be interesting for devices designed for the detection of radiations.

Two Sizes CdSe Quantum Dots Co-Sensitized TiO2-Nano-SiO2 Hybrid Photoelectrodes for Solar Cells Applications

2013 ◽  
Vol 575-576 ◽  
pp. 3-6
Author(s):  
Ren Bao Wang ◽  
Hai Hong Niu ◽  
Lei Wan
Keyword(s):  
Quantum Dots ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Crystallization Property ◽  
Free Carriers ◽  
Recombination Processes

The high-quality two sizes CdSe quantum dots (QDs) with nearly monodisperse size and shape were synthesized by the employed hot injection method with some modifications. The nanoparticles diameters were to be 2.6nm and 3.0nm respectively. To improve crystallization property and specific surface area of TiO2 and to inhibit recombination processes of photoinduced electrons effectively, TiO2-nano-SiO2 hybrid films were prepared by adding proper meso-porous SiO2 into TiO2, in which the mass ratio of SiO2 to TiO2 was 5%. CdSe QDs were linked to TiO2-nano-SiO2 films using 3-mercaptopropionic acid to increase CdSe QDs adsorption. Two sizes CdSe QDs were achieved both to promote charge separation and to ensure the porper mobile pathway of free carriers. The J-V characterization showed that two sizes CdSe QDs co-sensitized TiO2-nano-SiO2 hybrid photoelectrodes had higher short circuit current density (JSC) and open circuit voltage (VOC), compared to one size CdSe QDs.

Mobility-Lifetime Products in Glow Discharge and RF Sputter Deposited A-Si:H

1994 ◽  
Vol 336 ◽  
Author(s):  
M. H. Farias ◽  
A. Roche ◽  
S. Z. Weisz ◽  
H. Jia ◽  
J. Shinar ◽  
...  
Keyword(s):  
Light Intensity ◽  
Glow Discharge ◽  
Comparative Study ◽  
Deposition Temperature ◽  
Charge Carriers ◽  
Dangling Bonds ◽  
Majority Carrier ◽  
Recombination Processes ◽  
Pool Model ◽  
Sputter Deposited

ABSTRACTA comparative study of the deposition temperature (Ts) dependence of the Mobility-lifetime (μτ) products of the charge carriers in glow-discharge and rf sputter-deposited a-Si:H is described and discussed. The Ts-dependence of the μτ's the majority carrier light-intensity exponents of the two types of films are strikingly similar. These observations lead to the conclusion that the structure of the recombination levels as well as the recombination processes are in accord with the “defect pool” Model, in contrast to previous suggestions. The differences between the two types of films thus appear to be limited to the differences in the concentrations of dangling bonds.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

Sign in / Sign up

Export Citation Format

Share Document