Preparation of atomic layer deposited vanadium dioxide thin films using tetrakis(ethylmethylamino) vanadium as precursor

Vanadium dioxide (VO2) thin films were deposited by atomic layer deposition (ALD) using tetrakis(ethylmethylamino) vanadium precursor and H2O oxidant at a temperature of 150 °C. Optimization of post-deposition annealing results in smooth, continuous VO2 films (thickness, t ~ 30 nm) with small grains, exhibiting a transition from semiconducting to metal phase, typically known as the metal-insulator transition (MIT), at ~ 72 °C with a switching ratio ~ 10 2 . Such films were produced with high repeatability on a wafer scale and have been successfully utilized in resistively-coupled oscillators and self-selected resistive devices. Under smaller process window, thin films (t ~ 30 nm) with very large grains have also been produced, exhibiting the MIT ratio ~ 10 3 , which is the highest achieved for the ALD VO2 films deposited on SiO2 substrates. Both types of films were characterized again after 120 days to access their stability in air, a property that was rarely investigated