Tuning electron-phonon interactions in graphene and its bilayer for sensitive bolometry
Abstract: Graphene's weak electron-phonon coupling and small electronic heat capacity are of considerable advantage for achieving highly sensitive state-of-the-art bolometers and fast single photon detectors. To design such a radiation detector, it is important to study electron-phonon interaction in graphene and its dependence on temperature, Fermi energy, disorder and number of layers. In this talk, I will discuss our recent experimental study on graphene-superconductor junctions. In these devices, the superconducting contacts effectively confine hot electrons inside a graphene absorber, allowing access to phonon cooling regime at low temperatures. At the same time, the DC transport conductance of the junction serves as a sensitive electron temperature thermometer. We measure the temperature and doping dependence of electron-phonon coupling in single and bilayer graphene. In single layer graphene we demonstrate a disorder modified T3 temperature dependence of phonon cooling power, which agrees with the theoretical predictions. Using an observed inverse Fermi energy dependence of the phonon cooling power in bilayer graphene, we propose a way to achieve even higher sensitivities while maintaining linear device operation.
Host: Jimmy Williams