Preparation of NaxWO3 (x= 1 and 0.75) Thin Films and Their Electrical Conduction Properties

The powders for the $Na_xWO_3$ (x= 1 and 0.75) sputtering targets were synthesized by the calcination in reductive atmosphere. Near single-phase $NaWO_3$ and single-phase $Na_{0.75}WO_3$ powder targets were prepared. By using the targets, thin films of each composition were deposited by rf magnetron sputtering on the $SiO_2$ (100 nm)/Si substrates and annealed by RTP (rapid thermal processing) for crystallization. In the case of the $NaWO_3$ composition, single-phase $Na_xWO_3$ thin films, where x was believed to be slightly less than 1, were fabricated accompanying the Na-diffusion into the substrates during RTP. However, in the case of the $Na_{0.75}WO_3$ thin film preparation, it was unable to make single-phase thin films. From the phase formation behaviors of both powders and thin films, it was revealed that $Na_xWO_3$ with nonstoichiometric composition of x, which was slightly less than 1, was favorable. The good electrical conduction properties were obtained from the single-phase $Na_xWO_3$ thin films. Their electrical resistivities were as low as $7.5{\times}10^{-4}{\Omega}{\cdot}cm$.

NaxWO3 (x= 1, 0.75) 박막 제조 및 전기전도 특성