Fast thermal relaxation in cavity-coupled graphene bolometers with a Johnson noise read-out

Abstract

High sensitivity, fast response time and strong light absorption are the most important metrics for infrared sensing and imaging. The trade-off between these characteristics remains the primary challenge in bolometry. Graphene with its unique combination of a record small electronic heat capacity and a weak electron-phonon coupling has emerged as a sensitive bolometric medium that allows for high intrinsic bandwidths. Moreover, the material's light absorption can be enhanced to near unity by integration into photonic structures. Here, we introduce an integrated hot-electron bolometer based on Johnson noise readout of electrons in ultra-clean hexagonal-boron-nitride-encapsulated graphene, which is critically coupled to incident radiation through a photonic nanocavity with Q = 900. The device operates at telecom wavelengths and shows an enhanced bolometric response at charge neutrality. At 5 K, we obtain a noise equivalent power of about 10 pW Hz, a record fast thermal relaxation time, <35 ps, and an improved light absorption. However the device can operate even above 300 K with reduced sensitivity. We work out the performance mechanisms and limits of the graphene bolometer and give important insights towards the potential development of practical applications.

On-Chip Ultrafast Plasmonic Graphene Hot Electron Bolometric Photodetector

“…The carrier concentrations in graphene and thus the electron temperature of hot electrons in graphene T e in a function of absorbed power is governed by the heat transfer equation [66,67]…”

“…All those parameters govern the heat dissipation in graphene and hence determine the electron temperature rise and distribution in graphene. The electronic thermal conductivity κ e is obtained from the Wiedemann-Franz relation that relates the thermal and electrical conductivity of metals and is expressed by [66,67]…”

Harvesting of the infrared energy: Direct collection, up-conversion, and storage

“…Most bolometers are made from oxides of manganese, cobalt, or nickel [3]. However, bolometer based on graphene layer was recently reported [4]. Such a bolometer allows one to sense tiny changes in thermal radiation and, therefore, represents a new type of device for quantum sensing and information processing.…”

Observations of Radiation‐Dominated Rapid Cooling of Structures Based on Carbon Nanotubes and Graphene

“…There has been growing interest in nanocarbon‐based emitters and absorbers of thermal radiation. Examples include graphene‐based optical detectors using various physical mechanisms such as bolometers, CNT‐based incandescent sources integrated with waveguides, graphene‐based high efficiency solar water desalination, exfoliated graphite composite structures used for steam generation with solar radiation, and nanodiamond powder, multiwall CNT, and carbon black being used as high‐surface‐emissivity coatings on aluminum panels to improve heat sinking . As seen in these examples, the nanoscale features of these carbon materials provide great flexibility for fashioning them into various structures and devices; the rapid radiative cooling property of carbon makes it a unique platform that can enable novel applications such as the previously mentioned heat engine .…”