Production of Small, Stable PbS/CdS Quantum Dots via Room Temperature Cation Exchange Followed by a Low Temperature Annealing Processes

In the present study, the microwave heating method was used to prepare cadmium sulfide quantum dots CdSQDs films. CdS nanoparticles size average obtained as (7nm). The morphology, structure and composition of prepared CdSQDs were examined using (FE-SEM), (XRD) and (EDX). Optical properties of CdSQDs thin films formed and deposited onto glass substrates have been studied at room temperature using UV/ Visible spectrophotometer within the wavelength of (300-800nm), and Photoluminescence (PL) spectrum. The optical energy gap (Eg) which estimated using Tauc relation was equal (2.6eV). Prepared CdS nanoparticles thin films are free from cracks, pinholes and have high adhesion to substrate.

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Influence of Al-Cu-Mn-Fe-Ti Alloy Composition and Production Parameters of Extruded Semi-Finished Products on their Structure and Mechanical Properties

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.265.456 ◽

2017 ◽

Vol 265 ◽

pp. 456-462 ◽

Cited By ~ 1

Author(s):

P.L. Reznik ◽

Mikhail Lobanov

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Thermal Treatment ◽

Low Temperature ◽

Room Temperature ◽

High Temperature Strength ◽

Ti Alloy ◽

Low Temperature Annealing ◽

Annealing Conditions ◽

Concentration Changes

Studies have been conducted as to the effect of Cu, Mn, Fe concentration changes in Al-Cu-Mn-Fe-Ti alloy, the conditions of thermal and deformational treatment of ingots and extruded rods 40 mm in diameter on the microstructure, phase composition and mechanical properties. It has been determined that changing Al-6.3Cu-0.3Mn-0.17Fe-0.15Ti alloy to Al-6.5Cu-0.7Mn-0.11Fe-0.15Ti causes an increase in the strength characteristics of extruded rods at the room temperature both after molding and in tempered and aged conditions, irrespective of the conditions of thermal treatment of the initial ingot (low-temperature annealing 420 °С for 2 h, or high-temperature annealing at 530 °С for 12 h). Increasing the extruding temperature from 330 to 480 °С, along with increasing Cu, Mn and decreasing Fe in the alloy Al-Cu-Mn-Ti, is accompanied by the increased level of ultimate strength in a quenched condition by 25% to 410 MPa, irrespective of the annealing conditions of the original ingot. An opportunity to apply the Al-6.3Cu-0.3Mn-0.17Fe-0.15Ti alloy with low-temperature annealing at 420 °С for 2 h and the molding temperature of 330 °С has been found to produce rods where, in the condition of full thermal treatment (tempering at 535 °С + aging at 200 °С for 8 hours), a structure is formed that ensures satisfactory characteristics of high temperature strength by resisting to fracture for more than 100 hours at 300 °С and 70 MPa.

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Vacancy Enhanced Boron Activation during Room Temperature Implantation and Low Temperature Annealing

MRS Proceedings ◽

10.1557/proc-610-b5.6 ◽

2000 ◽

Vol 610 ◽

Author(s):

Jian-Yue Jina ◽

Irene Rusakova ◽

Qinmian Li ◽

Jiarui Liu ◽

Wei-Kan Chu

Keyword(s):

Low Temperature ◽

Sheet Resistance ◽

Room Temperature ◽

Activation Barrier ◽

Promising Method ◽

Activation Mechanism ◽

Rich Region ◽

Shallow Junction ◽

Low Temperature Annealing ◽

Junction Formation

AbstractLow temperature annealing combined with pre-damage (or preamorphization) implantation is a very promising method to overcome the activation barrier in ultra-shallow junction formation. We have made a 32 nm p+/n junction with sheet resistance of 290 /sq. using 20 keV 4×1014 Ω/cm2 Si followed by 2 keV 1×1015 at./cm2 B implantation and 10 minutes 550 °C annealing. This paper studies the boron activation mechanism during low temperature annealing. The result shows that placing B profile in the vacancyrich region has much better boron activation than placing B profile in interstitial-rich region or without pre-damage. It also shows that a significant portion of boron is in substitutional positions before annealing. The amount of substitutional boron is correlated to the amount of vacancies (damage) by the pre-damage Si implantation. The result supports our speculation that vacancy enhances boron activation.

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Room temperature optical gain in sol‐gel derived CdS quantum dots

Applied Physics Letters ◽

10.1063/1.118017 ◽

1996 ◽

Vol 69 (21) ◽

pp. 3224-3226 ◽

Cited By ~ 83

Author(s):

J. Butty ◽

N. Peyghambarian ◽

Y. H. Kao ◽

J. D. Mackenzie

Keyword(s):

Quantum Dots ◽

Room Temperature ◽

Sol Gel ◽

Optical Gain ◽

Cds Quantum Dots

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Low-Temperature Growth of Inverted Hexagonal ZnS/CdS Quantum Dots: Functional and Luminescence Properties

Journal of Electronic Materials ◽

10.1007/s11664-014-3567-6 ◽

2014 ◽

Vol 44 (2) ◽

pp. 675-681 ◽

Cited By ~ 3

Author(s):

Hitanshu Kumar ◽

P. B. Barman ◽

Ragini Raj Singh

Keyword(s):

Quantum Dots ◽

Low Temperature ◽

Luminescence Properties ◽

Cds Quantum Dots ◽

Temperature Growth ◽

Low Temperature Growth

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Utilizing Cation Exchange Method to Produce Core/Shell PbS/CdS Quantum Dots with Stable Infrared Emission

Acta Chimica Sinica ◽

10.6023/a13010052 ◽

2013 ◽

Vol 71 (06) ◽

pp. 929

Author(s):

Qian Li ◽

Teng Zhang ◽

Hongwei Gu ◽

Fazhu Ding ◽

Fei Qu ◽

...

Keyword(s):

Quantum Dots ◽

Cation Exchange ◽

Infrared Emission ◽

Core Shell ◽

Cds Quantum Dots ◽

Exchange Method

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Transient Spectroscopy of Glass-Embedded Perovskite Quantum Dots: Novel Structures in an Old Wrapping

Zeitschrift für Physikalische Chemie ◽

10.1515/zpch-2018-1168 ◽

2018 ◽

Vol 232 (9-11) ◽

pp. 1495-1511 ◽

Cited By ~ 2

Author(s):

Oleg V. Kozlov ◽

Rohan Singh ◽

Bing Ai ◽

Jihong Zhang ◽

Chao Liu ◽

...

Keyword(s):

Quantum Dots ◽

Low Temperature ◽

Fiber Optics ◽

Room Temperature ◽

Colloidal Particles ◽

Thermal Quenching ◽

Quantum Yields ◽

Luminescent Solar Concentrators ◽

Doped Glasses ◽

Glass Matrices

Abstract Semiconductor doped glasses had been used by the research and engineering communities as color filters or saturable absorbers well before it was realized that their optical properties were defined by tiny specs of semiconductor matter known presently as quantum dots (QDs). Nowadays, the preferred type of QD samples are colloidal particles typically fabricated via organometallic chemical routines that allow for exquisite control of QD morphology, composition and surface properties. However, there is still a number of applications that would benefit from the availability of high-quality glass-based QD samples. These prospective applications include fiber optics, optically pumped lasers and amplifiers and luminescent solar concentrators (LSCs). In addition to being perfect optical materials, glass matrices could help enhance stability of QDs by isolating them from the environment and improving heat exchange with the outside medium. Here we conduct optical studies of a new type of all-inorganic CsPbBr3 perovskite QDs fabricated directly in glasses by high-temperature precipitation. These samples are virtually scattering free and exhibit excellent waveguiding properties which makes them well suited for applications in, for example, fiber optics and LSCs. However, the presently existing problem is their fairly low room-temperature emission quantum yields of only ca. 1%–2%. Here we investigate the reasons underlying the limited emissivity of these samples by conducting transient photoluminescence (PL) and absorption measurements across a range of temperatures from 20 to 300K. We observe that the low-temperature PL quantum yield of these samples can be as high as ~25%. However, it quickly drops (in a nearly linear fashion) with increasing temperature. Interestingly, contrary to traditional thermal quenching models, experimental observations cannot be explained in terms of a thermally activated nonradiative rate but rather suggest the existence of two distinct QD sub-ensembles of “emissive” and completely “nonemissive” particles. The temperature-induced variation in the PL efficiency is likely due to a structural transformation of the QD surfaces or interior leading to formation of extremely fast trapping sites or nonemissive phases resulting in conversion of emissive QDs into nonemissive. Thus, future efforts on improving emissivity of glass-based perovskite QD samples might focus on approaches for extending the range of stability of the low-temperature highly emissive structure/phase of the QDs up to room temperature.

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