n-type CdTe:In for photovoltaics: in situ doping, type verification and compensation effects

Theodore D.C. Hobson, Luke Thomas, Laurie J. Phillips, Leanne A. H. Jones, Matthew J. Smiles, Christopher H. Don, Pardeep Kumar Thakur, Huw Shiel, Stephen Campbell, Vincent Barrioz, Vin R. Dhanak, Tim D. Veal, Jonathan D. Major, Ken Durose*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We explored the in-situ doping of cadmium telluride thin films with indium to produce n-type absorbers as an alternative to the near-universal choice of p-type for photovoltaic devices. The films were grown by close space sublimation from melt-synthesised feedstock. Transfer of the indium during film growth was limited to 0.0014%–0.014%—unless reducing conditions were used which yielded 14%–28% efficient transport. While chunks of bulk feedstock were verified as n-type by the hot probe method, carrier type of thin film material was only able to be verified by using hard x-ray photoelectron spectroscopy to determine the Fermi level position within the band gap. The assignment of n-type conductivity was consistent with the rectification behaviour of a p-InP/CdTe:In junction. However, chloride treatment had the effect of compensating n-CdTe:In to near-intrinsic levels. Without chloride, the highest dopant activation was 20% of the chemical concentration of indium, this being for a film having a carrier concentration of n = 2 × 1015 cm−3. However, the activation was often much lower, and compensation due to over-doping with indium and native defects (stoichiometry) are discussed. Results from preliminary bifacial devices comprising Au/P3HT/ZnTe/CdTe:In/CdS/FTO/glass are presented.
Original languageEnglish
Article number045012
Number of pages13
JournalJournal of Physics: Energy
Issue number4
Early online date29 Sept 2023
Publication statusPublished - 1 Oct 2023

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