Graphene-based, mid-infrared, room-temperature pyroelectric bolometers with ultrahigh temperature coefficient of resistance

TL;DR

This paper introduces a graphene-based mid-infrared photodetector at room temperature with an ultrahigh temperature coefficient of resistance, achieved through a novel charge-concentrating structure, enabling highly sensitive thermal detection for MIR applications.

Contribution

It presents a new graphene-based MIR photodetector with a record-high temperature coefficient of resistance, utilizing a floating metallic structure for charge concentration and high gain.

Findings

Temperature coefficient of resistance up to 900%/K

Detection resolution down to 15 microkelvin at 1 Hz

High gain (up to 200) in pyroelectric response

Abstract

Graphene is ideally suited for photonic and optoelectronic applications, with a variety of photodetectors (PDs) in the visible, near-infrared (NIR), and THz reported to date, as well as thermal detectors in the mid-infrared (MIR). Here, we present a room temperature-MIR-PD where the pyroelectric response of a LiNbO3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene, leading to a temperature coefficient of resistance up to 900%/K, two orders of magnitude higher than the state of the art, for a device area of 300x300um2. This is achieved by fabricating a floating metallic structure that concentrates the charge generated by the pyroelectric substrate on the top-gate capacitor of the graphene channel. This allows us to resolve temperature variations down to 15umK at 1 Hz, paving the way for a new generation of detectors for MIR imaging and spectroscopy