Composition-tuned band gap energy and refractive index in GaSxSe1-x layered mixed crystals

IŞIK M., Gasanly N.

MATERIALS CHEMISTRY AND PHYSICS, cilt.190, ss.74-78, 2017 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 190
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1016/j.matchemphys.2016.12.059
  • Dergi Adı: MATERIALS CHEMISTRY AND PHYSICS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.74-78
  • Anahtar Kelimeler: Semiconductors, Band gap energy, Refractive index, OPTICAL-PROPERTIES, GASE, ALLOYS
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

Transmission and reflection measurements on GaSxSe1-x mixed crystals (0 <= x <= 1) were carried out in the 400-1000 nm spectral range. Band gap energies of the studied crystals were obtained using the derivative spectra of transmittance and reflectance. The compositional dependence of band gap energy revealed that as sulfur (selenium) composition is increased (decreased) in the mixed crystals, band gap energy increases quadratically from 1.99 eV (GaSe) to 2.55 eV (GaS). Spectral dependencies of refractive indices of the mixed crystals were plotted using the reflectance spectra. It was observed that refractive index decreases nearly in a linear behavior with increasing band gap energy for GaSxSe1-x mixed crystals. Moreover, the composition ratio of the mixed crystals was obtained from the energy dispersive spectroscopy measurements. The atomic compositions of the studied crystals are well-matched with composition x increasing from 0 to 1 by intervals of 0.25. (C) 2016 Elsevier B.V. All rights reserved.