Oxygen-free atomic layer deposition of indium sulfide

Robert F. McCarthy, Matthew S. Weimer, Jonathan Daniel Emery, Adam S. Hock, Alex B.F. Martinson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Atomic layer deposition (ALD) of indium sulfide (In2S 3) films was achieved using a newly synthesized indium precursor and hydrogen sulfide. We obtain dense and adherent thin films free from halide and oxygen impurities. Self-limiting half-reactions are demonstrated at temperatures up to 225 °C, where oriented crystalline thin films are obtained without further annealing. Low-temperature growth of 0.89 Å/cycle is observed at 150 °C, while higher growth temperatures gradually reduce the per-cycle growth rate. Rutherford backscattering spectroscopy (RBS) together with depth-profiling Auger electron spectroscopy (AES) reveal a S/In ratio of 1.5 with no detectable carbon, nitrogen, halogen, or oxygen impurities. The resistivity of thin films prior to air exposure decreases with increasing deposition temperature, reaching <1 ω·cm for films deposited at 225 °C. Hall measurements reveal n-type conductivity due to free electron concentrations up to 1018 cm-3 and mobilities of order 1 cm2/(V·s). The digital synthesis of In2S 3 via ALD at temperatures up to 225 °C may allow high quality thin films to be leveraged in optoelectronic devices including photovoltaic absorbers, buffer layers, and intermediate band materials.

Original languageEnglish (US)
Pages (from-to)12137-12145
Number of pages9
JournalACS Applied Materials and Interfaces
Volume6
Issue number15
DOIs
StatePublished - Aug 13 2014

Keywords

  • Atomic layer deposition
  • in situ measurements
  • indium sulfide
  • indium(III) amidinate
  • photovoltaics
  • surface reactions

ASJC Scopus subject areas

  • Materials Science(all)

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