Structural and optical properties of Ag₂S thin films prepared by spray pyrolysis^*

¹ Laboratoire de Physique de la Matière Condensée, Faculté des Sciences de Tunis, Campus Universitaire, 2092 Tunis, Tunisia
² Laboratoire d'Analyse des Interfaces et de Nanophysique, Faculté des Sciences et Techniques de Montpellier, place Eugène Bataillon, 34095 Montpellier II Cedex 5, France

Received: 4 February 1997
Revised: 31 July 1997
Revised: 22 November 1997
Accepted: 21 January 1998
Published online: 15 April 1998

Abstract

Silver sulphide Ag₂ S thin films have been prepared on pyrex glass substrates by the spray pyrolysis technique using silver acetate and thiourea as starting materials. The depositions were carried out in the range of substrate temperatures from 100 to 300 °C. Measurements of X-ray diffraction show that the deposited layers at 250 °C were well crystallized and oriented preferentially in the direction . Films surfaces were analysed by contact Atomic Force Microscopy (AFM) in order to understand the effect of the deposited temperature on the surface structure. On the other hand, from transmission and reflection spectra, the band gap energy determined is about 1.14 eV. In the same way, an iterative method based on the optical reflectance and transmittance of Ag₂S thin film prepared at 250 °C were used to obtain the refractive index and the extinction coefficient. Their values vary in the wavelength range 640-2200 nm from 2.38 to 2.81 and from 0.001 to 0.277 respectively.