A. Bouzidi

Structural and optical properties of spray-pyrolysed Bi2S3 thin films

Abstract Thin layers of bismuth trisulfide (Bi 2 S 3 ) have been prepared for the first time by the spray pyrolysis method on glass substrates from bismuth chloride (BiCl 3 ) and thiourea (CS(NH 2 ) 2 ) solutions with a concentration of 0.2 M. Films deposited on substrate at 570 K have a polycrystalline structure with crystallites size in the order of 120 A. X-Ray characterization by grazing angles diffraction (GAD) at 0.4 and 2° shows crystalline structures in surface and volume. Diffraction spectra of these films are indexed in the orthorhombic system. Studies of optical absorption in the energy range 1.5–4 eV indicate an optical gap of 1.66 eV. The Hall effect measurements indicate a carrier concentration of n =3.45×10 17 cm −3 .

Optical and photoelectrical properties of Bi2S3 thin films obtained by spray pyrolysis technique

Polycrystalline films of Bi2S3 compound have been prepared, at substrate temperature of 570 K, from Bismuth chloride (BiCl3) and Thiourea (CS (NH2)2) solutions. The structural characterisation has been carried out by the X-ray diffraction analysis (XRD). Study of optical properties shows that Bi2S3 compound has an allowed indirect transition at 1.43 eV energy. The photoelectrical parameters (diffusion length and lifetime) have been determined from the study of the photoconductivity.

Optical constants of InSe and In 4 Se 3 thin films in the far infrared region

Abstract By using the flash evaporation technique we have obtained InSe and In 4 Se 3 thin films, their reflectance measurements are recorded at ambient temperatures, in the far infrared range (50–400 cm −1 ) and for E polarisation. The theoretical curves of reflectivity show that optical properties are strongly dependent on the thickness of thin films. In order to determine the optical constants (i.e. the real and imaginary parts of respectively the refractive index and the dielectric function). Finally electrical parameters such as free carrier concentration and their scattering times and vibrational frequencies of phonons are determined by the fit of the reflectivity spectrum.

A MOS structure temperature characterization

Abstract As is known, during the realization of semiconductor made components or devices, defects appear which lead to electronic trapped states. Their energies are all located in the forbidden band called the band gap. These states are called surface states and hinder the good functioning of such components or devices. In order to improve the performances of these components it is very important to reduce the density of such surface states. To determine the density of these states we consider MOS capacitance which allows, in particular, the electronic study of the active interface states which are the origin of a lot of negative phenomena. Thus, the most important objective of this paper remains the study, the analysis and the temperature C—V characterisation of the MOS structure of Al/SiO 2 /Si type.