Diffusion, Drift, and Recombination of Holes In a-Si:H

1995 ◽  
Vol 377 ◽  
Author(s):  
R. Schwarz ◽  
F. Wang ◽  
S. Grebner ◽  
Q. Gu ◽  
E. A. Schiff
Keyword(s):  
Steady State ◽  
Light Intensity ◽  
Response Time ◽  
Diffusion Length ◽  
Amorphous Semiconductor ◽  
Einstein Relation ◽  
Small Signal ◽  
Electron Hole ◽  
Hole Recombination ◽  
Photocurrent Decay

ABSTRACTWe compare measurements in a-Si:H of ambipolar diffusion length Lamb (from steady-state photocarrier gratings (SSPG)) and hole drift Χ (t) (from time-of-flight (TOF)). Using the response time tR from small-signal photocurrent decay measurements, we find that the equation L2amb = 2 (kT/e) Χ (tR) /E is consistent with the measurements, where E is the electric field inducing hole drift in TOF. Several samples under different temperature and light intensity levels have been studied. This equation has several implications. Under the usual SSPG illumination conditions, electron-hole recombination occurs while holes are still occupying valence bandtail states; hence SSPG is not sensitive to hole capture by deep levels. Furthermore, the experiments show that the Einstein relation is valid for holes in a-Si:H. We are unaware of prior direct tests of this relation in an amorphous semiconductor.

Carrier Injection in a-Si:H P-I-N Devices: Hydrogen Redistribution and Defect Creation

1993 ◽  
Vol 297 ◽  
Author(s):  
J.M. Asensi ◽  
J. Andreu ◽  
J. Puigdollers ◽  
J. Bertomeu ◽  
J.C. Delgado
Keyword(s):  
Steady State ◽  
Mechanical Treatment ◽  
Energy Levels ◽  
Carrier Injection ◽  
Electron Hole ◽  
Defect Sites ◽  
Statistical Mechanical ◽  
Staebler Wronski Effect ◽  
Charged Defects ◽  
Hole Recombination

A straightforward analytical expression of the density-of-states (DOS) of a-Si:H valid in non-equilibrium steady state situation has been obtained. The model is based on a statistical-mechanical treatment of the hydrogen occupation for different defect sites. The broadening of available defect energy levels (defect pool) and the possibility of charged defects are taken into account. This leads to a new explanation of the Staebler-Wronski effect, based on the "conversion" of shallow charge centers to neutrals near the middle of the gap as a consequence of hydrogen redistribution induced by electron-hole recombination.

A steady-state and time-resolved photophysical study of CdTe quantum dots in water

2015 ◽  
Vol 14 (2) ◽  
pp. 397-406 ◽  
Author(s):  
Alessandro Iagatti ◽  
Luigi Tarpani ◽  
Eleonora Fiacchi ◽  
Laura Bussotti ◽  
Agnese Marcelli ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Steady State ◽  
Cdte Quantum Dots ◽  
Capping Agent ◽  
Electron Hole ◽  
Time Resolved ◽  
Cdte Qds ◽  
Recombination Processes ◽  
Photophysical Study ◽  
Hole Recombination

The non-radiative electron–hole recombination processes are predominant in alkyl-thiol capped CdTe QDs prepared in water and they are affected by the nature of the capping agent.

Optically Detected Magnetic Resonance and Double Beam Photoluminescence of CdS/HgS/CdS Nanoparticles

1998 ◽  
Vol 536 ◽  
Author(s):  
H. Porteanu ◽  
A. Glozman ◽  
E. Lifshitz ◽  
A. Eychmüller ◽  
H. Weller
Keyword(s):  
Optical Properties ◽  
Magnetic Resonance ◽  
Cds Nanoparticles ◽  
Electron Hole ◽  
Cladding Layer ◽  
Double Beam ◽  
Optically Detected Magnetic Resonance ◽  
Optically Detected ◽  
Cladding Layers ◽  
Hole Recombination

AbstractCdS/HgS/CdS nanoparticles consist of a CdS core, epitaxially covered by one or two monolayers of HgS and additional cladding layers of CdS. The present paper describes our efforts to identify the influence of CdS/HgS/CdS interfaces on the localization of the photogenerated carriers deduced from the magneto-optical properties of the materials. These were investigated by the utilization of optically detected magnetic resonance (ODMR) and double-beam photoluminescence spectroscopy. A photoluminescence (PL) spectrum of the studied material, consists of a dominant exciton located at the HgS layer, and additional non-excitonic band, presumably corresponding to the recombination of trapped carriers at the interface. The latter band can be attenuated using an additional red excitation. The ODMR measurements show the existence of two kinds of electron-hole recombination. These electron-hole pairs maybe trapped either at a twin packing of a CdS/HgS interface, or at an edge dislocation of an epitaxial HgS or a CdS cladding layer.

Pre-Industrial Experience in Solar Photocatalytic Mineralization of Real Wastewaters. Application to Pesticide Container Recycling

1999 ◽  
Vol 40 (4-5) ◽  
pp. 123-130 ◽  
Author(s):  
S. Malato ◽  
J. Blanco ◽  
C. Richter ◽  
B. Milow ◽  
M. I. Maldonado
Keyword(s):  
Organic Contaminants ◽  
Toxic Waste ◽  
Experimental Plant ◽  
Electron Hole ◽  
Particulate Suspensions ◽  
Photocatalytic System ◽  
Commercial Pesticide ◽  
Pesticide Container ◽  
By Products ◽  
Hole Recombination

Particulate suspensions of TiO2 irradiated with natural solar tight in a large experimental plant catalyse the oxidation of organic contaminants. The problem in using TiO2 as a photocatalyst is electron/hole recombination. One strategy for inhibiting e−/h+ recombination is to add other (irreversible) electron acceptors to the reaction. In many highly toxic waste waters where degradation of organic pollutants is the major concern, the addition of an inorganic anion to enhance the organic degradation rate may be justified. For better results, these additives should fulfil the following criteria: dissociate into harmless by-products and lead to the formation of ·OH or other oxidising agents. In this paper, we attempt to demonstrate the optimum conditions for the treatment of commercial pesticide rinsates found in the wastewater produced by a pesticide container recycling plant. The experiments were performed in one of the pilot plants of the largest solar photocatalytic system in Europe, the Detoxification Plants of the Plataforma Solar de Almería (PSA), in Spain. After testing ten different commercial pesticides, results show that peroxydisulphate enhances the photocatalytic miniralization of all of them. This study is part of an extensive project focused on the design of a solar photocatalytic plant for decontamination of agricultural rinsates in Almería (Spain).

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