Electroluminescent Devices Made from Silicon Nanocrystals Embedded in Various Host Matrices

1996 ◽  
Vol 452 ◽  
Author(s):  
Gildardo R. Delgado ◽  
Howard W. H. Lee ◽  
Khashayar Pakbaz
Keyword(s):  
Silicon Nanocrystals ◽  
Impact Excitation ◽  
Optical And Electrical Properties ◽  
Carrier Injection ◽  
Electron Hole ◽  
Electroluminescent Devices ◽  
Advantages And Disadvantages ◽  
Si Nanocrystals ◽  
Host Matrices ◽  
Hole Recombination

AbstractSi nanocrystals produced by ultrasonic fracturing of porous silicon (PSi) were used to fabricate electroluminescent (EL) devices. The active EL material consists of Si nanocrystals embedded in various host matrices such as polyvinylcarbazole (PVK), polymethylmethacrylate (PMMA), and silica sol-gels. Several device configurations were used to induce EL processes that rely on radiative electron-hole recombination via carrier injection or impact excitation of the nanocrystals. We report on the optical and electrical properties of these devices. We discuss relevant physics pertaining to the Si nanocrystals/host and discuss advantages and disadvantages among the different host matrices.

Anisotropic Strain – Anisotropic Heating Engineering for Silicon Nanocrystals in SiO2

2009 ◽  
Vol 156-158 ◽  
pp. 523-528 ◽  
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.

Impact excitation of Er-doped GaAs and the rare-earth sites in III-V compound semiconductors

1993 ◽  
Vol 301 ◽  
Author(s):  
S. J. Chang ◽  
K. Takahei ◽  
J. Nakata ◽  
Y. K. Su
Keyword(s):  
Energy Transfer ◽  
Interstitial Site ◽  
Impact Excitation ◽  
Electron Hole ◽  
Pl Spectra ◽  
Gaas Substrates ◽  
Tetrahedral Interstitial Site ◽  
Different Temperatures ◽  
Er Doped ◽  
Hole Recombination

ABSTRACTWe report the first study of impact excitation of Er ions in GaAs. The MOCVDgrown, p+-n structured EL devices were fabricated by growing, at different temperatures, GaAs:Er layers on top of the n+ GaAs substrates. P+ layers were made by Zn diffusion from the top surfaces. When we forward biased these diodes, their EL spectra were similar to their respective PL spectra for each sample but different from each other's. However, when we reverse biased these diodes, EL spectra obtained from all samples are the same, which were different from their PL spectra. These results indicate that the Er center(s) excited by direct impact is different from the Er center(s) excited through electron-hole recombination and subsequent energy transfer. By using RBS channeling, we found that most of the Er ions, in our MOCVD-grown GaAs:Er samples, occupy a displaced tetrahedral interstitial site. From these PL, EL and RBS results, we conclude that only a small amount of Er ions emit luminescence when they are indirectly excited through energy transfer.

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.

Blue Electroluminescent Devices Fabricated from Silicon and Germanium Nanocrystals

1997 ◽  
Vol 471 ◽  
Author(s):  
Gildardo R. Delgado ◽  
Howard W. H. Lee ◽  
Khashayar Pakbaz
Keyword(s):  
Flat Panel Display ◽  
Electron Hole ◽  
Small Organic Molecules ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Si Nanocrystals ◽  
Germanium Nanocrystals ◽  
Silicon And Germanium ◽  
The Cost ◽  
Hole Recombination

ABSTRACTBlue electroluminescent (EL) devices were fabricated with Si nanocrystals produced by ultrasonic fracturing of porous silicon (PSi) as well as silicon and germanium nanocrystals synthesized through a control chemical reaction. The active EL material consists of Si and Ge nanocrystals embedded in various host matrices such as polyvinylcarbazole (PVK), polymethylmethacrylate (PMMA), silica sol-gels and other organic polymers and small organic molecules. Several device configurations were used to induce EL processes that rely on radiative electron-hole recombination within the nanocrystals. We report on the optical and electrical properties of these devices. Applications for these EL devices include highly efficient light emitting devices. The cost and ease of processing of these material systems make them potentially ideal for flat panel display applications.

Luminescent Nanometer-Sized Si Crystals Formed in an amorphous Silicon Dioxide Matrk by Ion Implantation and Annealing

1995 ◽  
Vol 388 ◽  
Author(s):  
T.S. Iwayama ◽  
Y. Terao ◽  
A. Kamiya ◽  
M. Takeda ◽  
S. Nakao ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Annealing Time ◽  
Band Gap Energy ◽  
Electron Hole ◽  
Quantum Confinement Effects ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Average Size ◽  
Si Ion Implantation ◽  
Hole Recombination

AbstractSi ion implantation followed by thermal annealing has been used to synthesize luminescent nanometer-sized Si crystals in an amorphous Si02 matrix. Transmission electron microscopy indicates the formation of Si nanocrystals by annealing at 1100 °C, and the growth in average size of Si nanocrystals with increasing annealing time. the shape of the emission spectrum of the photoluminescence is found to be independent of both excitation energy and annealing time, while the excitation spectrum of photoluminescence increases as the photon energy increases and its shape depends on annealing time. the results indicate that the photons are absorbed by Si nanocrystals, for which the band-gap energy is modified by the quantum confinement effects, and the emission of photons is not due to direct electron-hole recombination inside Si nanocrystals but is related to defects probably at the interface between Si nanocrystals and Si02.

Recovery of Bipolar-Current Induced Degradations in High-Voltage Implanted-Gate Junction Field Effect Transistors

2012 ◽  
Vol 717-720 ◽  
pp. 1013-1016
Author(s):  
Victor Veliadis ◽  
Harold Hearne ◽  
W. Chang ◽  
Joshua D. Caldwell ◽  
Eric J. Stewart ◽  
...  
Keyword(s):  
High Voltage ◽  
Elevated Temperatures ◽  
Field Effect Transistors ◽  
Stacking Faults ◽  
Vertical Channel ◽  
Electrical Characteristics ◽  
Carrier Injection ◽  
Electron Hole ◽  
Blocking Voltage ◽  
Hole Recombination

Electron-hole recombination-induced stacking faults have been shown to degrade the electrical characteristics of SiC power pin and MPS diodes and DMOSFETs with thick drift epitaxial layers. In this paper, we investigate the effects of bipolar injection induced stacking faults on the electrical characteristics of p+ ion-implanted high-voltage vertical-channel JFETs with 100-μm drift epilayers. The JFETs were stressed at a fixed gate-drain bipolar current density of 100 A/cm2 for five hours, which led to degradation of the forward gate-drain p-n junction and on-state conduction. The degradation was fully reversed by annealing at 350 °C for 96 hours. Forward and reverse gate-source, transfer, reverse gate-drain, and blocking voltage JFET characteristics exhibit no degradation with bipolar stress. Non-degraded characteristics remain unaffected by annealing events. Consequently, should minority carrier injection occur in JFETs operating at elevated temperatures no stacking fault induced degradations are expected. This eliminates the need for specialty substrates with suppressed densities of basal plane dislocations in the fabrication of high-voltage SiC JFETs for high temperature applications.

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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