Fabrication and evaluation of artificial neuron devices that uses vanadium dioxide

It was shown that VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> thin films undergo phase transition from insulator to metal near 70 °C. VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> is often formed by (Atomic Layer Deposition) ALD. In this study, we prepared VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> thin films using reactive sputtering of O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and Ar, and annealed them in oxygen ambient. We furthermore compared atomic composition of VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> film formed on different substrate such as SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>, and SiN, to analyze the elemental compositions of the VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> film. Elemental ratio of O/V of VOx film formed on SiO2 was between 1.5 and 2.0 throughout the film, however, it decreased from 2.0 to 1.0 in the VOx formed on SiN. It was suggested that VOx on SiO2 might exhibit a stable metal-insulator transition. Using X-ray diffraction we confirmed that the peak of VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> (2, 0, −2) existed in the VOx film after annealing in the oxygen ambient. It was suggested that polycrystalline VO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> was formed.