Naresh K

Department of Software Systems

School of Computer Science and Engineering

Vellore Campus

Ghosh K

Srichakradhar Reddy N.

Fulltext

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Theoretical optimization of multi-layer InAs/GaAs quantum dots subject to post-growth thermal annealing for tailoring the photoluminescence emission beyond 1.3 μm

Journal of Applied Physics

Journal of Computational Electronics

Theoretical analysis and optimization of high-k dielectric layers for designing high-performance and low-power-dissipation nanoscale double-gate MOSFETs

Experimental and theoretical study of polarization-dependent optical transitions in InAs quantum dots at telecommunication-wavelengths (1300-1500 nm)

The effects of thermal annealing on the large monolayer (11 ML) coverage of In0.45Ga0.55AsGaAs quantum dots (QDs) is being investigated in this study. Low temperature (8 K) photoluminescence (PL) spectra exhibits suppressed blueshift of the strongest PL emission peak even at high temperature annealing (800 °C). TEM and DCXRD characterizations showed the existence of the dots with good crystalline quality at annealing temperatures of 800850 °C. The physics of annealing induced compositional modification of the InGaAs QDs with various monolayer coverage has been studied by a theoretical model and simulation. All our studies establish the thermal stability of large ML coverage InGaAs QDs, which is desirable for optoelectronic devices required for selective wavelength tuning in specific applications. © 2011 Elsevier Ltd. All rights reserved.

Solid State Communications

Annealing of In0.45Ga0.55AsGaAs quantum dots overgrown with large monolayer (11 ML) coverage for applications in thermally stable optoelectronic devices

Morphological and optical properties of MBE-grown single and bilayer InAs/GaAs quantum-dot heterostructure with comparatively larger monolayer coverage (∼3.3 ML) are investigated. As compared to the similar single-layer quantum-dot (SQD) structure, the bilayer quantum-dot (BQD) structure showed a more uniform spatial distribution and increased size homogeneity of the dots. It also exhibited longer wavelength photoluminescence (PL) emission at room temperature, with the peak at a wavelength (1.34 μm) in the infrared communication window. The shift seen in the low temperature PL emission peak, even after annealing the BQD samples at temperatures up to 700°C, is negligible. However, the BQD samples showed an activation energy lower than that of the SQD sample, attributed to the In/Ga interdiffusion with the thin (8.5 nm thick) GaAs spacer layer during the growth process. Despite that, the higher thermal stability demonstrated by the BQD structure, along with a lower linewidth, makes the bilayer quantum dots a desirable proposition for efficient lasing devices requiring strict tolerances on operating wavelength. © 2010 Springer-Verlag.

Applied Physics A: Materials Science and Processing

Investigation of the effect of larger monolayer coverage in the active layer of bilayer InAs/GaAs quantum-dot structure and effects of post-growth annealing

Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena

Polarized emission from GaN/AlN quantum dots subject to uniaxial thermal interfacial stresses

We present a model for the effect of thermal annealing on a single-layer InAs/GaAs quantum dot (QD) heterostructure and study the corresponding variation in full photoluminescence (PL) spectrum. In/Ga interdiffusion due to annealing is modeled by Fickian diffusion and the Schrödinger equation is solved separately for electrons and holes to obtain ground state PL peaks of the heterostructure at different annealing temperatures. We theoretically examine the decrease in strain effects and carrier confinement potentials with annealing. PL spectra of the entire ensemble of QDs, annealed at different temperatures, are calculated from a lognormal distribution of QD heights derived from experimental atomic force microscopy (AFM) data. Results from our calculations, which illustrate the blueshift in emission wavelength and linewidth variation in PL with annealing, are in excellent agreement with experimental PL observations on the same samples. This highlights the potential of the model to assist in precisely engineering the optical properties of QD materials for specific device applications. Moreover, the simplicity of the model and its multiple useful features including computation of material interdiffusion, band profiles and full PL spectra make it a valuable tool to study annealing effects on QD heterostructures. © 2010 American Institute of Physics.

Presentation and experimental validation of a model for the effect of thermal annealing on the photoluminescence of self-assembled InAs/GaAs quantum dots

Journal	Data powered by TypesetJournal of Applied Physics
Publisher	Data powered by TypesetAIP Publishing
ISSN	0021-8979
Open Access	0