Controlled reactive HiPIMS-effective technique for low-temperature (300 degrees C) synthesis of VO2 films with semiconductor-to-metal transition

摘要

Reactive high-power impulse magnetron sputtering with a pulsed O-2 flow control and to-substrate O-2 injection into a high-density plasma in front of the sputtered vanadium target was used for low-temperature (300 degrees C) deposition of VO2 films with a pronounced semiconductor-to-metal transition onto conventional soda-lime glass substrates without any substrate bias voltage and without any interlayer. The depositions were performed using an unbalanced magnetron with a planar target of 50.8 mm diameter in argon-oxygen gas mixtures at the argon pressure of 1 Pa. The deposition-averaged target power density was close to 13 W cm(-2) at a fixed duty cycle of 1% with a peak target power density up to 5 kW cm(-2) during voltage pulses ranged from 40 mu s to 100 mu s. A high modulation of the transmittance at 2500 nm (between 51% and 8% at the film thickness of 88 nm) and the electrical resistivity (changed 350 times) at the transition temperature of 56-57 degrees C was achieved for the VO2 films synthesized using 50 mu s voltage pulses when the crystallization of the thermochromic VO2(M1) phase was supported by the high-energy (up to 50 eV relative to ground potential) ions. Principles of this effective low-temperature deposition technique with a high application potential are presented.