Photoconductivity activation in PbS thin films grown at room temperature by chemical bath deposition

This work is focused on the activation of the photoconduction in lead sulfide (PbS) thin films deposited by chemical bath deposition (CBD). The films were chemically deposited from an aqueous solution of lead nitrate [Pb(NO3)2], sodium hydroxide (NaOH) and thiourea [SC(NH2)2]. Thirty minutes after immersing the substrates in the solution, the thickness of the film remained unchanged, suggesting that lead and sulphur ions had been fully consumed. Thus, thicker films were obtained depositing additional PbS from a fresh solution. The films were treated at 473 K under oxygen residual pressure of 1.33×10−2 Pa. Photoconductivity measurements showed that the heat treatment activated the mechanism of photoconduction and the best results were obtained using two deposition steps.