Search query: development of quantum dot/quantum well

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abstract: The device characteristics of semiconductor lasers have been improved with progress in active layer structures. Carrier confinement dimension plays an important role especially in temperature sensitivity as well as slope efficiency. Three dimensional carrier confinement to nano scale semiconductor crystal, known as "quantum dots (QDs)" had been predicted to show ultimately superior device performances. Self assembly formed InAs QDs grown on GaAs had been intensively promoted in order to achieve QD lasers with superior device performances. Now high density, high optical quality QDs have been realized through improved molecular beam epitaxy growths and QD lasers with better temperature characteristics are in the stage of mass production for a data com market. Fabry Perot type, as well as distributed feedback type QD lasers show quite improved laser characteristics. Also, the unique device characteristics of QD lasers opened new application fields such as the use for resource searching by utilizing high temperature operation such as lasing at higher than 200 degC. For silicon photonics, QD lasers are used as an optical source for athermal operation. In this paper, the evolution of QDs, as well as improved device performances for novel application fields are discussed.
author_names: Kenichi Nishi

Keizo Takemasa

Mitsuru Sugawara

Yasuhiko Arakawa
title: Development of Quantum Dot Lasers for Data Com and Silicon Photonics Applications
venue: IEEE Journal of Selected Topics in Quantum Electronics
year: 2017

abstract: The electronic and thermal properties of bulk materials are altered when they are incorporated into quantum wells. Two dimensional quantum wells have been synthesized by alternating layers of B/sub 4/C and B/sub 9/C in one system and alternating layers of Si and Si/sub 0.8/G/sub 0.2/ in another system. Such nanostructures are being investigated as candidate thermoelectric materials for high figures of merit (Z) The predicted enhancement is attributed to the confined motion of charge carriers and phonons in the two dimensions and separating them from the ion scattering centers. Molecular beam epitaxy (MBE) and sputtering techniques have been used to prepare these multilayer films. Films have been deposited on single crystal silicon substrates. The /spl alpha/ and /spl rho/ properties of these films have been determined over a broad range of temperatures from 4.2 K to 1200 K and were previously reported. The /spl alpha//sup 2//spl rho/ values for these P type B C and N type SiGe films were more than a factor of 10 to 30 times higher than bulk P type B C and N type SiGe. Several one and two couple devices were fabricated with P type B/sub 4/C/B/sub 9/C QW films and N type bulk Bi/sub 2/Te/sub 3/ One of these couples produced 0.182 milliwatt at a /spl Delta/T of a 50/spl deg/C. This device produced ten times more power than the bulk Bi/sub 2/Te/sub 3/ commercial material of the same dimensions and /spl Delta/T. Hi Z is also producing thicker B/sub 4/C/B/sub 9/C films >10 /spl mu/m) on thinner Si substrates <1 /spl mu/m) to minimize thermal bypass heat losses. Successful scale up of these films for the P leg is expected to yield a 1 cm square device that will produce /spl sim/5 Watts at a /spl Delta/T of 200/spl deg/C. With a minimum assumption for thermal losses the device efficiency should approach 20%
author_names: S Ghamaty

Norbert B Elsner
title: Development of quantum well thermoelectric device
venue: Eighteenth International Conference on Thermoelectrics. Proceedings, ICT'99 (Cat. No.99TH8407)
year: 1999

abstract: Standard GaAs/AlGaAs QWIPs are now well established for LWIR detection. The main advantage of this technology is the duality with the technology of commercial GaAs devices. The second advantage widely claimed for QWIPs is the so called band gap engineering, allowing the custom design of the quantum structure to fulfill the requirements of specific applications such as multispectral detection. QWIPS are close to being optimized. The understanding of detection mechanisms has led to high performance QWIPs working at high temperature (above 77 K) However, as with all quantum detectors, the operating temperature of QWIPs is limited by the thermal current. A new skimmed architecture accommodating this offset has already been demonstrated. The optimization of a skimmed structure requires the modeling procedures and the process, to be adapted. We present the current status of QWIPs in France, including the latest performances achieved with both standard and skimmed architectures. We illustrate the development of our QWIPs by recent results on FPAs.
author_names: Eric Costard

Philippe Bois

Xavier Marcadet

Eric Herniou

Philippe M Tribolet

Michel Vuillermet
title: Development of quantum well infrared photodetectors in France
venue: SPIE Optics Photonics
year: 2000

abstract: Quantum well solar cells, as a promising approach for next generation photovoltaic technology, have received great attention in the last few years. Recent developments in materials growth and device structures of quantum wells have opened up new avenues for the incorporation of quantum well structures in next generation III/V multi junction solar cells. In this paper, the advantages and challenges of growing quantum wells in the unintentionally doped (i) region of p i n solar cells are reviewed. We focus on the recent progress in 1.1 1.3 eV strain balanced InGaAs/GaAsP, 1.6 1.8 eV strain balanced and lattice matched InGaAsP/InGaP, and >2.1 eV strained InGaN/GaN quantum well solar cells, including optimization of the quantum well growth conditions and improving the solar cell structure. For each material system, the challenges associated with materials growth and device performance such as critical layer thickness constraints, strain balance, bandgap tunability, and carrier transport limitations, are discussed. The performance of each quantum well solar cell is compared with bulk absorber operating in the same bandgap range, with the advantages of each being highlighted. The effect of the unintentional background doping on carrier collection (by drift) is presented through modeling and recent experimental results. The recent strategies to enhance the electric field distribution across the quantum well region are reviewed. The potential of incorporating quantum well structures in next generation multi junction devices is also discussed.
author_names: Islam Sayed

Salah M Bedair
title: Quantum Well Solar Cells: Principles, Recent Progress, and Potential
venue: IEEE Journal of Photovoltaics
year: 2019

abstract: The use of Al<inf>z</inf>In<inf>1 z</inf>As metamorphic buffer layers to facilitate the growth of lattice mismatched InN<inf>y</inf>(As<inf>1 x</inf>Sb<inf>x</inf><inf>1 y</inf> quantum wells on GaAs or InAs substrates has recently been demonstrated to constitute an attractive approach to developing light emitting devices at application rich mid infrared wavelengths. However, little information is available regarding the fundamental properties of this newly established platform. We present a theoretical investigation and optimisation of the properties and performance of InN<inf>y</inf>(As<inf>1 x</inf>Sb<inf>x</inf><inf>1 y</inf>/Al<inf>z</inf>In<inf>1 z</inf>As structures designed to emit at 3.3 and 4.2 mm. We quantify the design space available to these structures in terms of the ability to engineer and optimise the optoelectronic properties, and quantify the potential of metamorphic InN<inf>y</inf>(As<inf>1 x</inf>Sb<inf>x</inf><inf>1 y</inf> structures for the development of mid infrared light emitters, providing guidelines for the design of optimised light emitting diodes.
author_names: Reza Arkani

Christopher A Broderick

Eoin P O'Reilly
title: Design of 3.3 and 4.2 mm mid infrared metamorphic quantum well light emitting diodes
venue: 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)
year: 2018

abstract: Radiative recombination is studied in CdHgTe/HgTe QWs with bandgap in the 40 140 meV range using four band Kane model. Calculated radiative lifetimes agree well with the photoconductivity kinetics measurements. We show that the side maxima in the valence band hinder the radiative recombination at high carrier concentrations and discuss how to overcome this effect for the development of long wavelength lasers.
author_names: V Ya Aleshkin

Alexander A Dubinov

Vladimir V Rumyantsev

Mikhail A Fadeev

O L Domnina

Nikolai N Mikhailov

Sergey A Dvoretsky

Frederic Teppe

Vladimir I Gavrilenko

S V Morozov
title: Radiative recombination in narrow gap HgTe/CdHgTe quantum well heterostructures for laser applications.
venue: Journal of physics. Condensed matter an Institute of Physics journal
year: 2018

abstract: Transition state force fields (TSFF) treated the TS structure as an artificial minimum on the potential energy surface in the past decades. The necessary parameters were developed either manually or by the Quantum to molecular mechanics method (Q2MM) In contrast with these approaches, here we propose to model the TS structures as genuine saddle points at the molecular mechanics level. Different methods were tested on small model systems of general chemical reactions such as protonation, nucleophilic attack, and substitution, and the new procedure led to more accurate models than the Q2MM type parametrization. To demonstrate the practicality of our approach, transferrable parameters have been developed for Mo catalyzed olefin metathesis using quantum mechanical properties as reference data. Based on the proposed strategy, any force field can be extended with true transition state force field (TTSFF) parameters, and they can be readily applied in several molecular mechanics programs as well.
author_names: Adam Madarasz

Denes Berta

Robert S Paton
title: Development of a True Transition State Force Field from Quantum Mechanical Calculations.
venue: Journal of chemical theory and computation
year: 2016

abstract: Abstract In vitro expanded adipose derived stromal cells (ASCs) are a useful resource for tissue regeneration. Translation of small scale autologous cell production into a large scale, allogeneic production process for clinical applications necessitates well chosen raw materials and cell culture platform. We compare the use of clinical grade human platelet lysate (hPL) and fetal bovine serum (FBS) as growth supplements for ASC expansion in the automated, closed hollow fibre quantum cell expansion system (bioreactor) Stromal vascular fractions were isolated from human subcutaneous abdominal fat. In average, 95 x 106 cells were suspended in 10% FBS or 5% hPL medium, and loaded into a bioreactor coated with cryoprecipitate. ASCs (P0) were harvested, and 30 x 106 ASCs were reloaded for continued expansion (P1) Feeding rate and time of harvest was guided by metabolic monitoring. Viability, sterility, purity, differentiation capacity, and genomic stability of ASCs P1 were determined. Cultivation of SVF in hPL medium for in average nine days, yielded 546 x 106 ASCs compared to 111 x 106 ASCs, after 17 days in FBS medium. ASCs P1 yields were in average 605 x 106 ASCs (PD [population doublings] 4.65) after six days in hPL medium, compared to 119 x 106 ASCs (PD: 2.45) in FBS medium, after 21 days. ASCs fulfilled ISCT criteria and demonstrated genomic stability and sterility. The use of hPL as a growth supplement for ASCs expansion in the quantum cell expansion system provides an efficient expansion process compared to the use of FBS, while maintaining cell quality appropriate for clinical use. The described process is an obvious choice for manufacturing of large scale allogeneic ASC products.
author_names: Mandana Haack-Sorensen

Morten Juhl

Bjarke Follin

Rebekka Harary Sondergaard

Maria Kirchhoff

Jens Kastrup

Annette Ekblond
title: Development of large scale manufacturing of adipose derived stromal cells for clinical applications using bioreactors and human platelet lysate
venue: Scandinavian journal of clinical and laboratory investigation
year: 2018

abstract: As was recently shown by the authors, quantum probability theory can be used for the modelling of the process of decision making (e.g. probabilistic risk analysis) for macroscopic geophysical structures such as hydrocarbon reservoirs. This approach can be considered as a geophysical realization of Hilbert's programme on axiomatization of statistical models in physics (the famous sixth Hilbert problem) In this conceptual paper, we continue development of this approach to decision making under uncertainty which is generated by complexity, variability, heterogeneity, anisotropy, as well as the restrictions to accessibility of subsurface structures. The belief state of a geological expert about the potential of exploring a hydrocarbon reservoir is continuously updated by outputs of measurements, and selection of mathematical models and scales of numerical simulation. These outputs can be treated as signals from the information environment E. The dynamics of the belief state can be modelled with the aid of the theory of open quantum systems: a quantum state (representing uncertainty in beliefs) is dynamically modified through coupling with E; stabilization to a steady state determines a decision strategy. In this paper, the process of decision making about hydrocarbon reservoirs (e.g. 'explore or not? 'open new well or not? 'contaminated by water or not? 'double or triple porosity medium? is modelled by using the Gorini Kossakowski Sudarshan Lindblad equation. In our model, this equation describes the evolution of experts' predictions about a geophysical structure. We proceed with the information approach to quantum theory and the subjective interpretation of quantum probabilities (due to quantum Bayesianism) This article is part of the theme issue 'Hilbert's sixth problem'
author_names: Miguel Angel Lozada Aguilar

Andrei Yu Khrennikov

Klaudia Oleschko
title: From axiomatics of quantum probability to modelling geological uncertainty and management of intelligent hydrocarbon reservoirs with the theory of open quantum systems
venue: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
year: 2018

abstract: A fluorescence sensing material based on quantum dots with excellent optical properties and molecularly imprinted polymer (QDs@MIP) with specific recognition has been developed. First the surface of CdSe/ZnS QDs was modified with ionic liquids (ILs) by electrostatic interaction. The fluorescence sensing material was constructed from anchoring the MIP layer on IL modified CdSe/ZnS QDs by copolymerization, which had been developed for the detection of carbaryl in rice and Chinese cabbage. The MIP fluorescence was more strongly quenched by carbaryl than the non imprinted polymer (NIP) fluorescence, which indicated that the QDs@MIP could selectively recognize the corresponding carbaryl. Furthermore, the developed QDs@MIP method was validated by HPLC and ELISA respectively, and the results of these methods were well correlated (R(2) 0.98) The fluorescence sensing material had obvious advantages, such as being easily prepared and having specific recognition and photostability. The developed method was simple and effective for the detection of carbaryl. And, it could also provide the technical support for the rapid detection in food safety fields.
author_names: Can Zhang

Hanyu Cui

Jian-Rong Cai

Yuqing Duan

Yuan Liu
title: Development of Fluorescence Sensing Material Based on CdSe/ZnS Quantum Dots and Molecularly Imprinted Polymer for the Detection of Carbaryl in Rice and Chinese Cabbage.
venue: Journal of agricultural and food chemistry
year: 2015