Optical properties of TlGaxIn1-xSe2-layered mixed crystals (0.5 <= x <= 1) by spectroscopic ellipsometry, transmission, and reflection

IŞIK M., Delice S., Gasanly N.

PHILOSOPHICAL MAGAZINE, cilt.94, sa.23, ss.2623-2632, 2014 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 94 Sayı: 23
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1080/14786435.2014.926038
  • Dergi Adı: PHILOSOPHICAL MAGAZINE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.2623-2632
  • Anahtar Kelimeler: semiconductors, optical properties, ellipsometry, SINGLE-CRYSTALS, TRAPPING CENTERS, TLGASE2, ABSORPTION, INTENSITY, TLINSE2, ALLOYS
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

The layered semiconducting TlGaxIn1-xSe2-mixed crystals (0.5 <= x <= 1) were studied for the first time by spectroscopic ellipsometry measurements in the 1.2-6.2 eV spectral range at room temperature. The spectral dependence of the components of the complex dielectric function, refractive index, and extinction coefficient were revealed using an optical model. The interband transition energies in the studied samples were found from the analysis of the second-energy derivative spectra of the complex dielectric function. The effect of the isomorphic cation substitution (indium for gallium) on critical point energies in TlGaxIn1-xSe2 crystals was established. Moreover, the absorption edge of TlGaxIn1-xSe2 crystals have been studied through the transmission and reflection measurements in the wavelength range of 500-1100 nm. The analysis of absorption data revealed the presence of both optical indirect and direct transitions. It was found that the energy band gaps decrease with the increase of indium content in the studied crystals.