Journal of Alloys and Compounds, Volume 550, 15 February 2013, Pages 471-474.
I. Guler, M. Ambrico, T. Ligonzo, N.M. Gasanly
Material Science and Engineering Department, Cankaya University, Ankara, Turkey
CNR-Istituto di Metodologie Inorganiche e dei Plasmi-UOS di Bari, 70125 Bari, Italy
Dipartimento Interateneo di Fisica Università degli Studi di Bari “Aldo Moro”, 70125 Bari, Italy
Physics Department, Middle East Technical University, Ankara 06800, Turkey
Temperature variation of indirect band gap of Tl2In2S3Se layered single crystals were obtained by means of absorption and photoconductivity measurements. The temperature coefficient of −7.1 × 10−4 eV/K from absorption measurements in the temperature range of 10–300 K in the wavelength range of 520–1100 nm and −5.0 × 10−4 eV/K from PC measurements in the temperature range of 132–291 K in the wavelength range of 443–620 nm upon supplying voltage V = 80 V were obtained. From the analysis of dark conductivity measurements in the temperature range of 150–300 K, conductivity activation energy was obtained as 0.51 eV above 242 K. The degree of the disorder, the density of localized states near Fermi level, the average hopping distance and average hopping energy of Tl2In2S3Se crystals were found as, 1.9 × 105 K,Nf = 4 × 1020 cm−3eV−1, 29.1 Å and 24.2 meV in the temperature range of 171–237 K, respectively. Activation energy of hopping conductivity at T = 171 K was obtained as 41.3 meV and the concentration of trapping states was found as 1.6 × 1019 cm−3.