CdTe Thin Films from Nanoparticle Precursors by Spray Deposition

Douglas L. Schulz, Martin Pehnt, Doug H. Rose, Ed Urgiles, Andrew F. Cahill, David W. Niles, Kim M. Jones, Randy J. Ellingson, Calvin J. Curtis, David S. Ginley

Research output: Contribution to journalArticlepeer-review

26 Scopus Citations


The formation of CdTe thin films by spray deposition using nanoparticle colloids has been investigated. Employing a metathesis approach, cadmium iodide is reacted with sodium telluride in methanol solvent, resulting in the formation of soluble NaI and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe colloids prepared by this method exhibit a dependence of the nanoparticle diameter upon reaction temperature as determined by UV-visible spectroscopy (UV-vis), X-ray diffraction (XRD), and transmission electron microscopy (TEM). CdTe thin-film formation was performed by spray depositing the 25-75 Å diameter nanoparticle colloids according to a one- or two-step method. Films derived from a one-step approach were sprayed onto substrates at elevated temperatures (Tdep = 280-440°C) with no further thermal treatment. Two-step films were sprayed at lower temperatures (Tdep = 25-125°C) and were subjected to subsequent thermal treatments (Tanneal = 250-500°C) in argon or forming gas (10% H2 in N2) ambients. The effects of a CdCl2 treatment were also investigated for CdTe films on both 7059 glass and CdS on SnO2-coated 7059 glass. The CdTe films were characterized by XRD, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Phase-pure cubic CdTe formation was observed by XRD for two-step derived films (400°C in forming gas) while one-step films were composed of the cubic CdTe and an oxide phase. XPS analysis of five films processed at 400°C and a variety of conditions showed that while CdTe films produced by the one-step method contained no Na or C and substantial O, two-step films subjected to a CdCl2 treatment showed reduced O but increased C content. AFM gave CdTe grain sizes of ∼0.1-0.3 and ∼0.3-0.7 μm for a one-step film sprayed at 400°C and a two-step film annealed at 400°C, respectively. The potential of employing CdTe nanoparticles toward photovoltaic technologies is discussed.

Original languageAmerican English
Pages (from-to)889-900
Number of pages12
JournalChemistry of Materials
Issue number4
StatePublished - 1997

NREL Publication Number

  • NREL/JA-520-23346


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