Growth and Studies of II-VI Binary and Ternary Compounds: Nanostructures and Thin Films
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2016
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Abstract
CdSe and ZnSe are among II-VI compounds, which are of interest to scientific researchers over the past several decades due to their promising properties for potential applications in thin film solar cells, optical coatings, light emitting diodes, sensors, etc. These compounds have properties such as direct bandgap (CdSe ~ 1.68 eV and ZnSe ~ 2.7 eV at room temperature), (b) high absorption coefficient, and (c) high thermal stability, which are suitable for most electronic applications. Among II-VI ternary alloy semiconductors, ZnSxSe1-x and CdSxSe1-x are important due to their ideal tunable range of bandgap in the visible spectrum and the dual phonon mode properties. By controlling their composition, optical bandgap of ZnSxSe1-x and CdSxSe1-x compounds can be tuned between ~ 2.7 – 3.68 eV and ~ 1.68 – 2.42 eV respectively. The compositional change is also accompanied by corresponding changes in structural properties, which is also essential in material designing to achieve most suitable material for heterojunction devices. These alloys are among few mixed crystal systems exhibiting two-mode behavior of the phonons in which vibrational characteristics of both end binary compounds appear in the first order Raman spectra. Spin orbit (SO) coupling is a very important phenomenon, which affect the band structure in some of the II-VI compound semiconductors.
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Supervisor: Pratima Agarwal
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PHYSICS