Optimization of temperature coefficient of resistance of Al-doped vanadium oxide thin film prepared by atomic layer deposition for uncooled microbolometer.

Vanadium oxide (VO X) is an excellent thermal sensitive candidate for uncooled microbolometers. However, undoped VO X prepared by atomic layer deposition (ALD) has a temperature coefficient of resistance (TCR) of ca. −2 ∼ −3%/K. For improving its TCR, our deposition approach based on the combination of ALD and rapid post-deposition annealing (RTA) is proposed. Besides, aluminum-doping into the VO X films is performed via that approach, and the number of Al 2 O 3 cycles is adjusted for varying the dopant loadings. Changes in physical, chemical, and electrical characteristics of the VO X films due to Al-doping are discussed in detail. The advantage of introducing Al3+ dopants is to hinder the thermally activated phase transition of VO 2 phases, leading to an improvement in TCR of Al-doped VO X up to −4.2%/K, which remains stable over a wide temperature range of 298–328 K. However, the excessive Al doping also carries an adverse effect on TCR. The reason for that is discussed for further understandings of doping effects. [ABSTRACT FROM AUTHOR]