Tantalum nitride (TaNx) amorphous thin films with varying nitrogen content were grown on SiO2/Si using ionized physical vapor deposition. The composition of the films was examined by Rutherford back scattering spectrometry. The carrier density and the resistivity of TaNx films were measured by Hall effect and Van Der Pauw's method. TaNx thin films showed increased electrical resistivity and reduced carrier density as the amount of nitrogen was increased. By controlling the nitrogen content, the carrier density can be tuned within a large range of 1019-1022cm-3 for 3 and 15 nm thick TaNx films. The metallicity of the films was confirmed using ultraviolet photoemission spectroscopy. For 3 nm thick TaNx films, carrier densities of ∼1021cm-3 were obtained with the N2 flow rate in the range of 10-15 sccm. Such films have potential application in a quantum metal field effect transistor.