The ultrathin VO2(M) film with ultrahigh visible transmittance synthesized on the quartz glass substrate by HiPIMS

This paper described a high power impulse magnetron sputtering preparation of ultrathin polycrystalline VO2(M) thin film (<10 nm) on the quartz glass substrate. Combined with our experimental results, we find out that the integral visible transmittance changes with the thickness, and the ultrahigh transmittance values of 75.8% and 77.1% are obtained for the insulator and metal states, respectively. These results represent the best data for VO2 films to date. At lower substrate temperature, the room temperature structures for thicker films and thinner films are VO2(M) and VO2(B), respectively. The thinner VO2(M) films can only be successfully prepared by elevating substrate temperature to 485 °C. The phase transition temperature of the VO2(M) films shows little change with thickness at the same deposition temperature. In addition, the integral visible transmittance exceeds 54.8% for the thinner films deposited at 485 °C. Therefore, they are perfect smart window materials that need high visible transmittance.