scholarly journals Exciton-Photon Interactions in Semiconductor Nanocrystals: Radiative Transitions, Non-Radiative Processes and Environment Effects

2021 ◽  
Vol 11 (2) ◽  
pp. 497
Author(s):  
Vladimir A. Burdov ◽  
Mikhail I. Vasilevskiy
Keyword(s):  
Light Emission ◽  
Semiconductor Nanocrystals ◽  
Electronic Systems ◽  
Auger Process ◽  
Radiative Processes ◽  
Radiative Transitions ◽  
Environment Effects ◽  
Emission Decay ◽  
Photon Interactions ◽  
Physical Phenomena

In this review, we discuss several fundamental processes taking place in semiconductor nanocrystals (quantum dots (QDs)) when their electron subsystem interacts with electromagnetic (EM) radiation. The physical phenomena of light emission and EM energy transfer from a QD exciton to other electronic systems such as neighbouring nanocrystals and polarisable 3D (semi-infinite dielectric or metal) and 2D (graphene) materials are considered. In particular, emission decay and FRET rates near a plane interface between two dielectrics or a dielectric and a metal are discussed and their dependence upon relevant parameters is demonstrated. The cases of direct (II–VI) and indirect (silicon) band gap semiconductors are compared. We cover the relevant non-radiative mechanisms such as the Auger process, electron capture on dangling bonds and interaction with phonons. Some further effects, such as multiple exciton generation, are also discussed. The emphasis is on explaining the underlying physics and illustrating it with calculated and experimental results in a comprehensive, tutorial manner.

Correlation of Electronic and Thermal Properties of Short Channel nMOSFETS

1999 ◽  
Author(s):  
M. Palaniappan ◽  
V. Ng ◽  
R. Heiderhoff ◽  
J.C.H. Phang ◽  
G.B.M. Fiege ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Hot Spots ◽  
Light Emission ◽  
Photon Emission ◽  
Thermal Image ◽  
Short Channel ◽  
Physical Phenomena ◽  
Backside Illuminated

Abstract Light emission and heat generation of Si devices have become important in understanding physical phenomena in device degradation and breakdown mechanisms. This paper correlates the photon emission with the temperature distribution of a short channel nMOSFET. Investigations have been carried out to localize and characterize the hot spots using a spectroscopic photon emission microscope and a scanning thermal microscope. Frontside investigations have been carried out and are compared and discussed with backside investigations. A method has been developed to register the backside thermal image with the backside illuminated image.

Progress in the Light Emission of Colloidal Semiconductor Nanocrystals

Small ◽  
2010 ◽  
Vol 6 (13) ◽  
pp. 1364-1378 ◽  
Author(s):  
Nikolai Gaponik ◽  
Stephen G. Hickey ◽  
Dirk Dorfs ◽  
Andrey L. Rogach ◽  
Alexander Eychmüller
Keyword(s):  
Light Emission ◽  
Semiconductor Nanocrystals ◽  
Colloidal Semiconductor Nanocrystals ◽  
Colloidal Semiconductor

Bright White-Light Emission from Semiconductor Nanocrystals: by Chance and by Design

2007 ◽  
Vol 19 (4) ◽  
pp. 569-572 ◽  
Author(s):  
S. Sapra ◽  
S. Mayilo ◽  
T. A. Klar ◽  
A. L. Rogach ◽  
J. Feldmann
Keyword(s):  
White Light ◽  
Light Emission ◽  
Semiconductor Nanocrystals ◽  
White Light Emission ◽  
Bright White Light

scholarly journals Single-Component White Light Emitting CdSexSy Alloy Nanocrystals Through Phosphine-Free Route

2020 ◽  
Author(s):  
Shilpi Jaiswal ◽  
Jyotsana Pathak ◽  
Abhijit Patra
Keyword(s):  
Quantum Yield ◽  
White Light ◽  
Light Emission ◽  
Semiconductor Nanocrystals ◽  
White Light Emission ◽  
Molar Ratio ◽  
Visible Range ◽  
One Pot ◽  
Light Emitting ◽  
Hydrogel Matrix

Semiconductor nanocrystals are promising for display and lighting devices. Herein, we report a facile one-pot synthetic route to fabricate white light emitting CdSexSy nanocrystals with enhanced quantum yield using CdO, S powder, and Se powder as precursors. The phosphine-free route was adopted, employing paraffin oil as the reducing agent and solvent for the fabrication. The optical properties can be effectively tailored by controlling the reaction time and the molar ratio of Se/S. The emission of pristine CdSexSy nanocrystals covered a broad visible range from 400 to 750 nm. The CdSexSy nanocrystals (Se/S = 0.4) exhibited white-light emission with quantum yield of 50 ± 3 % and Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.30, 0.31). The band-edge (~400-450 nm) to trap-state (~550-750 nm) emissions was tuned by controlling the Se/S ratio, and the different shades of white light were obtained. Furthermore, the quantum yield and CIE coordinates of the CdSexSy nanocrystals (Se/S = 0.4) were found to be similar even after 30 days of fabrication, showing the high stability of nanocrystals. The white light emission was retained in nanocrystals-embedded poly(methyl methacrylate) (PMMA) thin film and also in the hydrogel matrix. The one-pot, low-cost, scalable fabrication of white light emitting CdSexSy nanocrystals demonstrated in the present study offers promising scope in the solid-state display applications. <br>

Role of Non-Radiative Transitions in X-RAY Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 10-11
Author(s):  
János L. Lábár
Keyword(s):  
Excited Atom ◽  
Fluorescence Yield ◽  
Initial State ◽  
Radiative Process ◽  
X Ray ◽  
Radiative Processes ◽  
Radiative Transitions ◽  
The Given ◽  
Electron Shells

Radiative and non-radiative transitions present alternative ways for the excited atom to reduce its energy when the initial state is an atom singly ionised in one of its inner electron shells. Since the fluorescence yield gives the probability that the empty state in the inner (sub)shell is filled in by a radiative process, it seems that the generated x-ray intensities are independent of the non-radiative rearrangements from the point on where the value of fluorescence yield is given for the (sub)shell in question. In that way the intensity of an x-ray line would solely be dependent on the ionisation probability of the given (sub)shell and on the rates of the radiative transitions (determining the relative intensities of the lines originating from the same subshell). That image involves that the non-radiative processes only influence the value of the fluorescence yield. For the simplest case i.e. for the K shell it is true.

Particle generation and recombination

2020 ◽  
pp. 417-453
Author(s):  
Sandip Tiwari
Keyword(s):  
Impact Ionization ◽  
Radiative Lifetime ◽  
Momentum Conservation ◽  
Recombination Coefficient ◽  
Auger Process ◽  
Particle Generation ◽  
Radiative Processes ◽  
High Concentrations ◽  
Energy And Momentum ◽  
Energetic Interactions

This chapter introduces a semi-classical interpretation of particle generation and recombination using the bimolecular recombination coefficient and radiative lifetime. Particles—electrons and holes in the semiconductor—can be generated and recombine because of the multitude of energetic interactions. Radiative recombination and generation arise in the interaction with photons and can be spontaneous or stimulated. Important non-radiative processes such as the Hall-Shockley-Read process and the Auger process, which arise in multiparticle interactions, are discussed. Auger recombination is common at small bandgaps and high concentrations but also appears in large bandgap materials under high injection conditions. Impact ionization is an example of Auger generation arising from high fields. The Auger process is analyzed quantum-mechanically to show how energy and momentum conservation equations and quantum restrictions lead to the observed behavior. The chapter also discusses recombination at surfaces, which is inevitably present because of the defects and confined states arising from symmetry breaking.

scholarly journals MECHANISM OF BIJUNCTION SEMICONDUCTOR DEVICE DAMAGE INDUCED BY HEAVY PARTICLES

2015 ◽  
Vol 78 (2-2) ◽  
Author(s):  
Saafie Salleh ◽  
Fuei Pien Chee ◽  
Haider F. Abdul Amir
Keyword(s):  
Semiconductor Device ◽  
High Energy ◽  
Electronic Systems ◽  
Heavy Particles ◽  
Energetic Ions ◽  
Bipolar Junction Transistor ◽  
Energy Gamma ◽  
Junction Transistor ◽  
Γ Rays ◽  
Physical Phenomena

The physical phenomena associated with the stopping of energetic ions in semiconductor materials have always been a subject which receives great theoretical and experimental interest. Consequently, bombardment of high energy particles and high energy gamma (γ) rays causes potential hazards to these electronic systems. These effects range from degradation of performance to functional failure that can affect the system operations. Such upsets becoming increasingly likely as electronic components are getting more sophisticated while decreasing in size and moves to larger integration. In this paper, the penetration of gamma rays, utilizing Cobalt-60 (Co-60)) into bipolar junction transistor (BJT) is being simulated using the program simulation SRIM. From the findings, it is observed that the penetration of Co-60 ions into the simulated BJT leads to production of lattice defects in the form of vacancies, defect clusters and dislocations. These can alter the material parameters and hence the functional properties of the devices.

Light Emission from Carbon Nanotubes Induced by Field Electron Emission from Oriented MWCNT Arrays Accompanied by Re-Deposition

2004 ◽  
Vol 858 ◽  
Author(s):  
R. Nanjundaswamy ◽  
Al. A Zakhidov ◽  
M. Zhang ◽  
S. B. Lee ◽  
W. M. Sampson ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electron Emission ◽  
Light Emission ◽  
Emission Spectra ◽  
Chemical Vapor ◽  
Applied Bias Voltage ◽  
Multiwalled Carbon ◽  
Fe Catalyst ◽  
Aligned Arrays ◽  
Radiative Transitions

AbstractWell-ordered aligned arrays of multiwalled carbon nanotubes were synthesized by the catalytic thermal chemical vapor deposition (CVD) in acetylene gas at the atmospheric pressure. Abrupt spark–type light emission spots and release of the carbon nanotubes from the cathode and succeeding deposition onto the anode without decomposition has been detected above the threshold electron emission current. Spectral analysis of the light showed that the spectra consist of a background similar to blackbody radiation and a set of sharp lines identified with the radiative transitions of excited carbon and iron atoms. Light emission spectra were found to be essentially different depending on the type (AC or DC) of the applied bias voltage and its value. As-grown and re-deposited materials were characterized by Raman spectroscopy and scanning electron microscopy. It was found that the structural properties of the re-deposited carbon nanotubes remained intact, with only negligible amorphization. A mechanism of the spark emission and re-deposition processe is proposed and discussed in terms of fast overheating of CNT, after explosion type melting of Fe-catalyst nanoclusters, followed by CNT transfer from cathode to anode.

Effect of Ion Doping with Donor and Acceptor Impurities on Intensity and Lifetime of Photoluminescence from SiO2 Films with Silicon Quantum Dots

2008 ◽  
Vol 8 (2) ◽  
pp. 780-788 ◽  
Author(s):  
A. N. Mikhaylov ◽  
D. I. Tetelbaum ◽  
V. A. Burdov ◽  
O. N. Gorshkov ◽  
A. I. Belov ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emission ◽  
Ion Irradiation ◽  
Radiative Lifetime ◽  
Photoluminescence Intensity ◽  
Radiative Processes ◽  
Photoluminescence Decay ◽  
Si Nanocrystals ◽  
Donor And Acceptor ◽  
Control Light

Doping with donor and acceptor impurities is an effective way to control light emission originated from quantum-size effect in Si nanocrystals. Combined measurements of photoluminescence intensity and kinetics give valuable information on mechanisms of the doping influence. Phosphorus, boron, and nitrogen were introduced by ion implantation into Si+-implanted thermal SiO2 films either before or after synthesis of Si nanocrystals performed at Si excess of about 10 at.% and annealing temperatures of 1000 and 1100 °C. After the implantation of the impurity ions the samples were finally annealed at 1000 °C. It is found that, independently of ion kind, the ion irradiation (the first stage of the doping process) completely quenches the photoluminescence related to Si nanocrystals (peak at around 750 nm) and modifies visible luminescence of oxygen-deficient centers in the oxide matrix. The doping with phosphorus increases significantly intensity of the 750 nm photoluminescence excited by a pulse 337 nm laser for the annealing temperature of 1000 °C, while introduction of boron and nitrogen atoms reduces this emission for all the regimes used. In general, the effective lifetimes (ranging from 4 to 40 μs) of the 750 nm photoluminescence correlate with the photoluminescence intensity. Several factors such as radiation damage, influence of impurities on the nanocrystals formation, carrier-impurity interaction are discussed. The photoluminescence decay is dominated by the non-radiative processes due to formation or passivation of dangling bonds, whereas the intensity of photoluminescence (for excitation pulses much shorter than the photoluminescence decay) is mainly determined by the radiative lifetime. The influence of phosphorus doping on radiative recombination in Si quantum dots is analyzed theoretically.

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