  Atomic layer deposition was used to synthesize niobium silicide (NbSi) films
with a 1:1 stoichiometry, using NbF5 and Si2H6 as precursors. The growth
mechanism at 200oC was examined by in-situ quartz crystal microbalance (QCM)
and quadrupole mass spectrometer (QMS). This study revealed a self-limiting
reaction with a growth rate of 4.5 {\AA}/cycle. NbSi was found to grow only on
oxide-free films prepared using halogenated precursors. The electronic
properties, growth rate, chemical composition, and structure of the films were
studied over the deposition temperature range 150-400oC. For all temperatures,
the films are found to be stoichiometric NbSi (1:1) with no detectable fluorine
impurities, amorphous with a density of 6.65g/cm3, and metallic with a
resistivity {\rho}=150 {\mu}{\Omega}.cm at 300K for films thicker than 35 nm.
The growth rate was nearly constant for deposition temperatures between
150-275oC, but increases above 300oC suggesting the onset of non-self limiting
growth. The electronic properties of the films were measured down to 1.2K and
revealed a superconducting transition at Tc=3.1K. To our knowledge, a
superconducting niobium silicide film with a 1:1 stoichiometry has never been
grown before by any technique.
