Infrared micro-detectors with high sensitivity and high response speed using VO2-coated helical carbon nanocoils

Abstract

Bolometers for infrared detection by thermally induced resistance changes are indispensable components for extensive applications, in particular for security purposes. Microminiaturization is the direction of developing bolometers with a high performance and high resolution. However, the current micro-bolometers based on VO_x are still subject to low responsivity and low response speed. Further development of high-performance micro-bolometers requires new designs of both materials and structures. Herein, we developed helical-shaped micro-bolometers based on the composites of vanadium dioxide (VO₂) and carbon nanocoils (CNCs). It was shown that in the composite, the helical structure greatly enhanced the light absorption efficiency, the nanoscale diameter guaranteed small thermal capacitance, and the reversible phase transition of VO₂ led to a large resistance change. More importantly, VO₂/CNC bolometers showed a non-hysteretic response working in the phase-transition region. Due to the synergistic effect, the VO₂/CNC bolometers had a very high temperature coefficient of resistance up to 35%/K, ultrahigh responsivity of 3.3 × 10⁵ V W⁻¹, a short response time lower than 2 ms, and a long lifetime of more than 1 000 000 cycles, all of which were superior to those of VO_x-based bolometers. Our work reveals an inspiring strategy to prepare high-performance micro-bolometers, which will find potential applications in ultrasensitive thermal imaging and thermo-sensitive sensors.