Original scientific paper

Optical properties of AgBiS2 thin films

Alaa M. Ibrahim ; University College for Girls, Ain Shams University, Physics Dept., Heliopolis, Cairo, Egypt
Laila I. Soliman ; National Research Centre, Physics Department, Dokki, Cairo, Egypt

Abstract

Thin films of AgBiS2 were prepared by thermal evaporation in vacuum (at about 10-6 mbar). X-ray diffraction was used to determine the structural properties of the sample. The as-deposited films (at 300 K) were amorphous in nature and an amorphous-to-crystalline transition could be obtained by thermal annealing at 373 K. The degree of crystallinity increased with increasing temperature from 373 to 473 K. At 525 K, two-phase films with AgBiS2 as a major phase were formed. Optical constants of amorphous and crystalline AgBiS2 thin films were measured after various heat treatments. The analysis of optical absorption spectra revealed the existence of three optical transition mechanisms; allowed direct, forbidden direct and indirect transition, with optical energy gaps Ed = 2.88 eV, Ef = 2.04 eV and Ei = 1.78 eV at 300 K. These values were found to decrease at higher annealing temperatures.

Keywords

Hrčak ID:

299616

URI

https://hrcak.srce.hr/299616

Publication date:

1.10.1996.

Article data in other languages: croatian

Visits: 682 *