Metin Kul

Structural and optical properties of SnS semiconductor films produced by chemical bath deposition

SnS films have been deposited at room temperature by the chemical bath deposition technique. The films have been examined to evaluate their structure, morphology, composition and optical properties. SnS films were polycrystalline with an orthorhombic-herzenbergite structure. The lattice parameters and crystallite size of the sample have been calculated to be a = 4.39 A, b = 11.17 A, c = 3.97 A with a/c = 1.106, and 67 nm, respectively. SnS films have been well crystallized in the form of cylindrical rods and the atomic ratio of Sn to S is 49.8 : 50.2. The optical properties of the sample have been studied using the transmittance and reflectance measurements as a function of wavelength between 190 and 3300 nm. The optical band gap is direct with a value of 1.31 eV. The refractive index and extinction coefficient as a function of wavelength for the film were investigated from the transmittance spectrum by applying the envelope method. The optical parameters of the material such as dielectric constants (n, k, e1 and e∞), plasma frequency ωp and carrier concentration Nopt were also evaluated.

α-In2S3 and β-In2S3 phases produced by SILAR technique

In2S3 films have been deposited by the successive ionic adsorption and reaction technique (SILAR) at room temperature. The films have been examined to evaluate the structural and optical properties. X-ray diffraction spectra have revealed the presence of both the α-In2S3 (cubic) and β-In2S3 (tetragonal) phases. The presence of the α-In2S3 phase at room temperature is attributed to the richness of In in the deposited materials. The presence of both phases is also supported by FESEM observations. The crystallinity of the material has been observed to improve with increasing thickness. Direct band gap of the deposits decreased from 2.89 to 2.37 eV with increasing thickness.

Band Gap Energies of CdO:F Semiconductor Films Produced by Ultrasonic Spray Pyrolysis Method

The fluorine doped cadmium oxide (CdO:F) samples have been deposited by ultrasonic spray pyrolysis method (USP). The absorption spectra of the samples showed that CdO:F is a direct band gap material. The direct optical transition has shifted towards the shorter wavelengths, and the transparency of the material has increased at a given wavelength above the fundamental absorption edge. The optical band gap (Eg) has found to be 2,28 eV for undoped CdO films. A shift in the absorption edge of the fluorine doped CdO films with increasing fluorine concentration is explained by means of the Moss‐Burstein effect.