Manufacture and characterization of sol–gel V1−x−yWxSiyO2 films for uncooled thermal detectors

V1−x−yWxSiyO2 films for uncooled thermal detectors were coated on sodium-free glass slides with sol–gel process, followed by the calcination under a reducing atmosphere (Ar/H2 5%). The V1−x−yWxSiyO2 films as prepared inherit various phase transition temperatures ranging from 20 to 70°C depending on the dopant concentrations and the fabrication conditions. Compared to the hysteresis loop of plain VO2 films, a rather steep loop was obtained with the addition of tungsten components, while a relaxed hysteresis loop with the tight bandwidth was contributed by Si dopants. Furthermore, the films with switching temperature close to room temperature were fabricated to one-element bolometers to characterize their figures of merit. Results showed that the V0.905W0.02Si0.075O2 film presented a satisfactory responsivity of 2600V/W and detectivity of 9×106cm Hz1/2/W with chopper frequencies ranging from 30 to 60Hz at room temperature. It was proposed that with appropriate amount of silicon and tungsten dopants mixed in the VO2, the film would characterize both a relaxed hysteresis loop and a fair TCR value, which effectively reduced the magnitude of noise equivalent power without compromising its performance in detectivity and responsivity.