e-Article
Highly conductive and stable Co 9 S 8 thin films by atomic layer deposition: from process development and film characterization to selective and epitaxial growth.
Document Type
Academic Journal
Author
Mattinen M; Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Finland. mikko.ritala@helsinki.fi.; Hatanpää T; Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Finland. mikko.ritala@helsinki.fi.; Mizohata K; Department of Physics, University of Helsinki, P.O. Box 43, FI-00014, Finland.; Räisänen J; Department of Physics, University of Helsinki, P.O. Box 43, FI-00014, Finland.; Leskelä M; Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Finland. mikko.ritala@helsinki.fi.; Ritala M; Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Finland. mikko.ritala@helsinki.fi.
Source
Publisher: Royal Society of Chemistry Country of Publication: England NLM ID: 101176026 Publication Model: Electronic Cited Medium: Internet ISSN: 1477-9234 (Electronic) Linking ISSN: 14779226 NLM ISO Abbreviation: Dalton Trans Subsets: PubMed not MEDLINE; MEDLINE
Subject
Language
English
Abstract
Co 9 S 8 is an interesting sulfide material with metallic conductivity that has shown promise for various energy applications. Herein, we report a new atomic layer deposition process producing crystalline, pure, and highly conductive Co 9 S 8 thin films using CoCl 2 (TMEDA) (TMEDA = N , N , N ', N '-tetramethylethylenediamine) and H 2 S as precursors at 180-300 °C. The lowest resistivity of 80 μΩ cm, best uniformity, and highest growth rate are achieved at 275 °C. Area-selective deposition is enabled by inherent substrate-dependency of film nucleation. We show that a continuous and conductive Co 9 S 8 film can be prepared on oxide-covered silicon without any growth on Si-H. Besides silicon, Co 9 S 8 films can be grown on a variety of substrates. The first example of an epitaxial Co 9 S 8 film is shown using a GaN substrate. The Co 9 S 8 films are stable up to 750 °C in N 2 , 400 °C in forming gas, and 225 °C in O 2 atmosphere. The reported ALD process offers a scalable and cost-effective route to high-quality Co 9 S 8 films, which are of interest for applications ranging from electrocatalysis and rechargeable batteries to metal barrier and liner layers in microelectronics and beyond.