Prof. Meera Chandrasekhar Profile

Prof. Meera Chandrasekhar

at Univ of Missouri

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Publications (4)

Proceedings Article | 17 December 1999 Paper

Influence of the molecular geometry on the photoexcitations of highly emissive organic semiconductors

Shu-Chun Yang, Wilhelm Graupner, Suchismita Guha, Peter Puschnig, Chris Martin, Holakere Chandrasekhar, Meera Chandrasekhar, Guenther Leising, Claudia Ambrosch-Draxl

Proceedings Volume 3797, (1999) https://doi.org/10.1117/12.372714

KEYWORDS: Absorption, Polarons, Polymers, Luminescence, Excitons, Molecules, Solids, Dielectrics, Light emitting diodes, Modulation

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Proceedings Article | 13 October 1995 Open Access

Polarization puzzles for the upper elementary grades

Meera Chandrasekhar, David Rainwater, Rebecca Litherland, Rodney Swope, Ann VanNest

Proceedings Volume 2525, (1995) https://doi.org/10.1117/12.224011

KEYWORDS: Polarizers, Polarization, Linear polarizers, Glasses, Molybdenum, Molecules, Physics, Lamps, Light emitting diodes, Heat treatments

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Proceedings Article | 24 April 1995 Paper

Optical, electronic, magnetic, and superconducting properties of quasiperiodic quantum dot arrays synthesized by a novel electrochemical technique

Supriyo Bandyopadhyay, A. Miller, Meera Chandrasekhar

Proceedings Volume 2397, (1995) https://doi.org/10.1117/12.206875

KEYWORDS: Quantum dots, Aluminum, Magnetism, Cadmium sulfide, Superconductors, Transmission electron microscopy, Luminescence, Electrons, Crystals, Nickel

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Proceedings Article | 1 August 1990 Paper

Photoreflectance studies of electronic transitions in quantum well structures under high presure

Holakere Chandrasekhar, Meera Chandrasekhar

Proceedings Volume 1286, (1990) https://doi.org/10.1117/12.20849

KEYWORDS: Gallium arsenide, Quantum wells, Spectroscopy, Modulation, Gallium antimonide, Semiconductors, Quantum electronics, Superlattices, Heterojunctions, Luminescence

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Superlattices of alternating layers of semiconductors were first proposed1 in 1970, and since then a variety of structures have been grown. Their technological importance has spurred considerable experimental and theoretical work. The unique feature of quantum confinement of carriers has made possible unusual devices. By combining various semiconductors and alloys of ffl-V, 11-TV and group IV materials, unusual band lineups between neighboring layers have been obtained. Both lattice matched and strained layer structures have been grown. In this article we will focus on the electronic structure of the quantum well heterostructures under the external perturbation of hydrostatic pressure. Pressure has been used extensively to investigate materials in regions of phase space not otherwise accessib1. lu the study of quantum well structures, it has also been used to move band edges in a controlled fashion, and alter band lineups, allowing the determination of band offsets with an accuracy that was not possible without the use of pressure. As in bulk semiconductors, optical techniques provide powerful tools in studying the electronic states in quantum well heterostructures (QWH). Photoluminescence (PL) spectroscopy is only sensitive to spectral features associated with energy states close to the bottom of the well due to rapid thermalization of carriers. Photoluminescence excitation (PLE) is often limited by the availability of tunable lasers. Photoreflectance (PR), on the other hand, can provide a rich structure due to both symmetry allowed and forbidden transitions encompassing the entire quantum well. This sensitivity is due to the derivative nature of the spectroscopy. Experiments can be carried out easily at different temperatures and over wide spectral regions. This article is organized as follows. In section 2 we will review some of the theoretical calculations of electronic bands in quantum wells and discuss the changes expected under pressure. In Sec. 3, we discuss the experimental details, including descriptions of the optical techniques used. Section 4 will deal with studies of the quantized transitions in GaAs/GaixAlxAs and GaSb/A1Sb QWH under pressure,using PR and PL. The examples are illustrative of the comparative merits of the two techniques.

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