Low Power Resistive Photon and Gas Sensors

Abstract

Sensors, be it for temperature, pressure, acoustic, light or gas to name a few have become an indispensable part of human life. Light sensors or photodetectors have widespread usage in modern portable electronics as camera sensors, fibre optic communication systems, surveillance, firefighting and medical imaging amongst others. Commercial light sensors such as charge coupled device (CCD) and complementary metal-oxide-semiconductor (CMOS) detectors, used extensively for ultraviolet (UV) and visible detection, have a low responsivity of ~ 0.7 A/W. While high responsivity of ~ 50 A/W can be achieved using avalanche photodiodes (APDs), they operate under very high bias voltages (gt150 V). In infrared (IR) region, thermal and photodetectors are used. Thermal detectors are slow and have low photoresponse, while requiring the use of special filters for IR-only detection. On the other hand, photon detectors always require cooling for operation often up to cryogenic temperatures, increasing their power consumption. Hence, there is a clear need for the development of high response photodetectors with low power consumption across the UV, visible and IR regions. Gas sensors are widely used for the detection of combustible, flammable and toxic gases, or oxygen depletion. Also, with air pollution reaching alarming levels across the world, there is a demand for constant air quality monitoring and hence, the development of portable and low-cost gas sensors with low power consumption are of utmost importance. In this work, we have explored UV, visible/NIR and IR (gt1040 nm) photodetection using ZnO, Si and IrP2 nanoparticles (NPs) embedded few-layer graphene (FLG), respectively. ZnO with a bandgap of ~3.2 eV is suitable for UV photodetection. However, the exciton binding energy of ~60 meV leads to a high recombination and hence, low photoresponse...