NbCl5 as a precursor in atomic layer epitaxy

NbCl5 was examined as a niobium source for ALE growth of NbN and Nb2O5 films and for Nb doping of TiO2 and SnO2 films. The growth of NbN films was successfully accomplished both with and without reducing Zn pulses between the NbCl5 and NH3 pulses. The polycrystalline NbN films were nearly stoichiometric and free of chlorine residues. The main problem met was the low growth rate, only about 0.2 Å/cycle. All attempts to employ NbCl5 as a precursor in oxide processes failed which, with the aid of thermodynamic calculations, was ascribed to the stability of NbOCl3 and NbO2Cl intermediate products.