Highly sensitive hot electron bolometer based on disordered graphene

A bolometer is a device that makes an electrical resistive response to the electromagnetic radiation resulted from a raise of temperature due to heating. The combination of the extremely weak electron-phonon interactions along with its small electron heat capacity makes graphene an ideal material for applications in ultra-fast and sensitive hot electron bolometer. However, a major issue is that the resistance of pristine graphene weakly depends on the electronic temperature. We propose using disordered graphene to obtain a strongly temperature dependent resistance. The measured electrical responsivity of the disordered graphene bolometer reaches $6\times10^6$ V/W at 1.5 K, corresponding to an optical responsivity of $1.6\times10^5$ V/W. The deduced electrical noise equivalent power is 1.2 fW/$\sqrt{\rm Hz}$, corresponding to the optical noise equivalent power of 44 fW/$\sqrt{\rm Hz}$. The minimal device structure and no requirement of high mobility for graphene make a step forward towards the applications of graphene hot electron bolometers.