A highly stable, nanotube-enhanced, CMOS-MEMS thermal emitter for mid-IR gas sensing
D. Popa, Richard Hopper, Syed Zeeshan Ali, Matthew T. Cole, Ye Fan, Vlad-Petru Veigang-Radulescu, Rohit Chikkaraddy, Jayakrupakar Nallala, Yuxin Xing, Jack Alexander-Webber, Stephan Hofmann, Andrea De Luca, Julian W. Gardner, Florin Udrea
Abstract
The gas sensor market is growing fast, driven by many socioeconomic and industrial factors. Mid-infrared (MIR) gas sensors offer excellent performance for an increasing number of sensing applications in healthcare, smart homes, and the automotive sector. Having access to low-cost, miniaturized, energy efficient light sources is of critical importance for the monolithic integration of MIR sensors. Here, we present an on-chip broadband thermal MIR source fabricated by combining a complementary metal oxide semiconductor (CMOS) micro-hotplate with a dielectric-encapsulated carbon nanotube (CNT) blackbody layer. The micro-hotplate was used during fabrication as a micro-reactor to facilitate high temperature (>700 [Formula: see text]C) growth of the CNT layer and also for post-growth thermal annealing. We demonstrate, for the first time, stable extended operation in air of devices with a dielectric-encapsulated CNT layer at heater temperatures above 600 [Formula: see text]C. The demonstrated devices exhibit almost unitary emissivity across the entire MIR spectrum, offering an ideal solution for low-cost, highly-integrated MIR spectroscopy for the Internet of Things.