High-Resolution Uncooled Detector of Thermal Radiation with Resistivity Engineering

Uncooled infrared bolometers have become the technology of choice for applications such as thermography, firefighting, and night vision. These microbolometers detect thermal radiation from an object based on the Stefan–Boltzmann law with a thermal sensitivity, named as noise-equivalent differential temperature (NEDT). Existing methods to advance NEDT of the uncooled detectors are focused on the engineering side, with the efforts approaching the end of the roadmap. In this work, we take a distinct appoach on the material side and improve the key parameter, known as temperature coefficient of resistance, by 3 times over a wide temperature range. The abrupt change of resistance comes from the metal-insulator transition of vanadium dioxide while the broad working temperature range is realized by creating a gradient-doped tungsten-doped vanadium dioxide where the tungsten fraction is judiciously graded across a thickness comparable to real products.