Annealing effect on CdS films: Transition from glass to ITO

Abstract

Structural and optical properties of CdS films deposited on glass and ITO substrates and annealed in H2, N2 or H2+N 2 atmospheres at 250 °C and 400 °C were compared. The optical thickness 405±10 nm of the CdS films was found not to be influenced by any annealing conditions or substrate. The as deposited films on both substrates had similar diffraction patterns with one narrow peak corresponding to the (111) cubic plane at 2θ 26.70° and 26.75°, respectively. Higher density of nucleation centres on the ITO surface generated denser CdS films. In the annealing process of CdS/ITO a slower shift of both (111) peak and lattice constant was observed in the direction of pure zinc blende modification. Similar values of band gap and transmittance were determined for as-deposited CdS while annealing at 400 °C decreased transmittance by 5% and 16% for CdS on glass and ITO, respectively. Transmittance dropped because of the destruction of hydroxide group in the CdS lattice, the formation of cadmium excess and the reduction of SnO2 to black SnO in the ITO structure. © Published under licence by IOP Publishing Ltd.