High Rate Hot-Wire Chemical Vapor Deposition of Silicon Thin Films Using a Stable TaC Covered Graphite Filament

Ina T. Martin, Charles W. Teplin, Paul Stradins, Marc Landry, Maxim Shub, Robert C. Reedy, Bobby To, James V. Portugal, John T. Mariner

Research output: Contribution to conferencePaperpeer-review

16 Scopus Citations


We grow silicon films by hot-wire/catalytic chemical vapor deposition using a new filament material: TaC-coated graphite rods. The filaments are 1.6 mm diameter rigid graphite rods with ∼30 μm thick TaC coatings. Whereas heated W or Ta wire filaments are reactive and embrittle in silane (SiH 4), the TaC/graphite filament is stable. After > 2 h of exposure to SiH4 gas at a range of filament temperatures, the full length of a TaC/graphite filament retains its shiny golden color with no indication of swelling or degradation. In comparison, a W wire exposed to SiH4 under the same conditions becomes swollen and discolored at the cold ends, indicating silicide formation. Scanning electron microscopy images of the filament material are nearly identical before and after SiH4 exposure at 1500-2000 °C. This temperature-independent chemical stability could enable added control of the gas phase chemistry during deposition that does not compromise the filament lifetime. The larger surface area of the 1.6 mm diameter TaC coated graphite filament (compared to the 0.5 mm W filament) allows for a ∼ 2× increase in the deposition rate of Si thin films grown for photovoltaic applications.

Original languageAmerican English
Number of pages4
StatePublished - 2 May 2011
EventSixth International Conference on Hot-Wire CVD (Cat-CVD) Process - Paris, France
Duration: 13 Sep 201017 Sep 2010


ConferenceSixth International Conference on Hot-Wire CVD (Cat-CVD) Process
CityParis, France

NREL Publication Number

  • NREL/CP-520-47930


  • Filament
  • Hot-wire chemical vapor deposition
  • Silicidation
  • TaC


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