Abstract
High Resolution Image Download MS PowerPoint Slide The ability of VO 2 to undergo semiconductor-to-metal phase transition (SMT) upon heating makes it a very attractive material for uncooled bolometers. The SMT of VO 2 represents a large temperature coefficient of resistance, which is an important parameter for the development of highly responsive microbolometers. However, other characteristics of the SMT of VO 2 such as its high transition temperature (341.2 K), the sharpness of the transition, its hysteresis, and the high room temperature resistivity limit the performance of this material in microbolometers. In this work, we grow a high-quality epitaxial ultrathin film VO 2 on c -plane Al 2 O 3 by pulsed laser deposition. The low deposition temperature and tuning the oxygen partial pressure during the growth process enable control over the grain size and oxygen vacancy concentration. This allowed controlling the SMT parameters of the samples. In particular, we show that the high density of grain boundaries associated with nanosized grains suppresses the thermal hysteresis of the SMT. Simultaneous control over the density of oxygen vacancies and the size of grains enables the adjustment of the temperature coefficient of resistance, room temperature resistivity, SMT temperature, sharpness, and thermal hysteresis toward suitable values for the fabrication of efficient VO 2 -based uncooled bolometers. Compared with other VO 2 fabrication methods, this approach can be viewed as a simpler alternative for VO 2 fabrication with favorable properties for practical bolometer applications.