An investigation on palladium sulphide (PdS) thin films as a photovoltaic material

Polycrystalline PdS thin films with tetragonal structure have been grown by direct sulphuration of Pd layers. They are formed by crystallites of size similar to 50 nm. As-grown PdS films show a Seebeck coefficient, S= -250 +/- 30 mu V/K, which indicates an n-type conductivity. Electrical resistivity of the samples, measured by the four contact probe, is (6.0 +/- 0.6) x 10(-2) Omega cm. Hall effect measurements, confirms n-type conductivity with a negative carrier density n=(8.0 +/- 2.0) x 10(18) CM-3 and electron mobility mu of (20 +/- 2) cm(2)/V s. Band gap energy (E-g) and absorption coefficient (a) are determined from the optical transmission and reflectance of the films. A direct transition with energy gap E-g =(1.60 +/- 0.01) eV is obtained. Optical absorption coefficient in the range of photon energies hv > 2.0 eV is higher than 10(5) cm(-1). All these properties make PdS th in films a good alternative material for solar applications. (C) 2007 Elsevier B.V. All rights reserved.