Optical properties of GaS crystals: Combined study of temperature-dependent band gap energy and oscillator parameters

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Date

2017

Authors

Tugay,E.
Gasanly,N.

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National Institute of Science Communication and Information Resources (NISCAIR)

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Department of Electrical & Electronics Engineering
Department of Electrical and Electronics Engineering (EE) offers solid graduate education and research program. Our Department is known for its student-centered and practice-oriented education. We are devoted to provide an exceptional educational experience to our students and prepare them for the highest personal and professional accomplishments. The advanced teaching and research laboratories are designed to educate the future workforce and meet the challenges of current technologies. The faculty's research activities are high voltage, electrical machinery, power systems, signal and image processing and photonics. Our students have exciting opportunities to participate in our department's research projects as well as in various activities sponsored by TUBİTAK, and other professional societies. European Remote Radio Laboratory project, which provides internet-access to our laboratories, has been accomplished under the leadership of our department with contributions from several European institutions.

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Abstract

Optical parameters of gallium sulfide (GaS) layered single crystals have been found through temperature-dependent transmission and room temperature reflection experiments in the wavelength range of 400-1100 nm. Experimental data demonstrates the coexistence of both optical indirect and direct transitions and the shift of the absorption edges toward lower energies by increasing temperature in the range of 10-300 K. Band gap at zero temperature, average phonon energy and electron phonon coupling parameter for indirect and direct band gap energies have been obtained from the analyses of temperature dependences of band gap energies. At high temperatures kT″ <Eph>, rates of band gap energy change have been found as 0.56 and 0.67 meV/K for Egi and Egd, respectively. Furthermore, the dispersion of refractive index has been discussed in terms of the Wemple-DiDomenico single effective oscillator model. The refractive index dispersion parameters, namely oscillator and dispersion energies, oscillator strength and zero-frequency refractive index, have been found to be 4.48 eV, 24.8 eV, 6.99×1013 m2 and 2.56, respectively. The results of the present work will provide an important contribution to the research areas related to the characterization and optoelectronic device fabrication using GaS layered crystals.

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Keywords

GaS, Optical properties, Oscillator parameters, Single crystals

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Citation

5

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Q4

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Q3

Source

Indian Journal of Pure and Applied Physics

Volume

55

Issue

8

Start Page

583

End Page

588