Effects of aluminum doping upon properties of cadmium sulfide thin films and its effect on ITO/CdS:Al/NiOx/Ni/Au diodes

Abstract

We analyze the Al doping effect in CdS films by chemical bath deposition and how it impacts this doping effect in a heterojunction, for the case of ITO/CdS:Al/NiOx/Ni/Au. The results show that the doping effect of aluminum on the CdS films by chemical bath deposition does slightly affect the structural and morphological properties. The impact of the doping is related to the electrical properties; first, with a decrement in the resistivity from 108 to 107 Ω cm, the work function decreases from 4.7 to 4.3 eV, the bandgap and the valence band suffers a small increment of 0.1 eV. The change in the electrical properties impacts the diode behavior, and the increment in the work function leads to an increment of the Fermi energy level difference between NiOx and CdS:Al; this difference was reflected in a wider depletion region and a reduction of the leakage current.