Nanoantenna integrated narrowband photodetector for infrared gas sensing

Abstract

Nanoantenna based on surface plasma polariton (SPR) resonance effect has been integrated respectively with pyroelectric and thermopile infrared detectors. This on-chip integration has enabled narrowband infrared detector for miniaturization of Non-Dispersive Infrared (NDIR) gas sensors as well as multi-component gas sensing. Herein, we propose and construct nanoantenna integrated quantum dot photodetector to further overcome the limitations of thermal detectors such as relatively slow response and low detectivity. We focus on PbS colloidal quantum dots (CQDs) owing to their strong absorption toward near infrared light and convenient integration with silicon substrates. The PECVD grown SiO₂ and EBE grown Au nanodisks were subsequently deposited on PbS CQD layer to form a metal-insulator-semiconductor (MIS) architecture. Typically, the nanoantenna integrated photodetector exhibited a narrowband photoresponse at peak wavelength around 1300 nm, with a 24 % improvement in the responsivity compared to conventional devices. NDIR gas-sensing studies based on the nanoantenna integrated narrowband photodetector show that the selectivity for specific gases (CH₄ and NH₃ in this study) is obtained without the need for additional narrowband filters, and lower detection limits are also achieved because of the higher photoresponse at specific wavelength. Our proof-of-concept work demonstrates the advantages of nanoantenna integrated narrowband photodetector for infrared gas sensing.