Citrate-Controlled Solution Deposition of PbSe Thin Films

Chemical bath deposition is an efficient method to reproduce high-quality thin films. Extensive work has been done on the deposition of lead chalcogenides due to their technological importance as infrared detectors and emitters [1]. Our group has previously reported on the ability to obtain desirable microstructure of lead selenide at high pH (>13) by optimizing reactants concentration, temperature and growth duration [2,3]. There is an important advantage in understanding the kinetics influencing the deposition of PbSe at relatively low pH (<13) and gaining further control over film`s morphology related to optical properties. Trisodium citrate (TSC) is a commonly used co-complexing agent during chemical deposition of the lead selenide, which allowed us to deposit films at lower pH, yet its exact role has not been systematically studied [3]. This work focuses on the effect of citrate and pH on the kinetics involved in the deposition of PbSe.The film microstructure and optical properties were studied as a function of citrate concentration. The optical band gap presented a strong dependence on citrate concentration due to quantum confinement. Two distinct morphologies were found in the film, a nanocrystalline layer followed by columnar grains. Photoluminescence showed two different peaks that were correlated with the different morphologies. The results are in good agreement with simple particle-in-a-box quantum confinement models, with a weaker confinement observed for the 2D columnar region.

[1] A. Rogalski, Infrared Detectors, vol. 1, no. 1. 2011.

[2] T. Templeman, M. Biton, T. Safrani, M. Shandalov, E. Yahel, and Y. Golan, “Chemically deposited PbSe thin films: factors deterring reproducibility in the early stages of growth,” CrystEngComm, vol. 16, no. 46, pp. 10553–10559, 2014.

[3] Gary Hodes, Chemical Solution Deposition of Semiconductor Films, vol. 1139, no. 20715. 2006.