Evolution of Pb(1-x)Sn(x)Te thin films from dendrites to nanoparticles on gold substrates by electrodeposition

Dendritic and nanostructured Pb(1-x)Sn(x)Te thin films were synthesized on gold substrates from acidic solutions through a simple electrodeposition route. The deposition potential of thin films was determined using cyclic voltammetry. All of the thin films were deposited in both the absence and presence of cetyltrimethylammonium bromide (CTAB) as a cationic surfactant. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier transform infrared (FT-IR) spectroscopy were employed to characterize the deposits. XRD results showed that the diffraction peaks shift to larger angles as mole fraction x increases, indicating the formation of Pb(1-x)Sn(x)Te alloy. Morphological analysis revealed that the obtained thin films in the absence of CTAB were composed of dendrites, while the obtained thin films in the presence of CTAB were made of nanoparticles. Growth mechanisms for the dendritic and nanostructured thin films were discussed. The optical absorption studies show that the band gap of Pb(1-x)Sn(x)Te thin films grown with short deposition times could be tuned from 0.21 to 0.35 eV by adding only the surfactant to the deposition solution.