Figure 1: GNR superlattice photodetector.
From: Photocurrent in graphene harnessed by tunable intrinsic plasmons
(a) scanning electron microscopy close-up of the contact area of a GNR array photodetector with 100 nm GNR width and 100 nm GNR spacing. Scale bar, 2 μm. The length and width of the entire array are 30 and 10 μm, respectively. (b) Schematic of the photoconductivity setup. Infrared laser light at 10.6 μm is chopped at 1.1 KHz and the photocurrent is analysed by a lock-in amplifier referenced to the chopping frequency. (c) Illustration of the mechanism of phonon and hot electron generation through decay of the hybrid plasmon–phonon quasi-particles. S-polarized infrared light excites primarily the plasmon–phonon mode, while p-polarized light excites individual electron–hole pairs. The plasmon–phonon quasi-particle decays mainly through SP phonons into other phonons, while electron–hole pairs decay primarily into hot electrons. Electrons thermalize among themselves at a temperature Te, and phonons among themselves at a temperature Tph. A bottleneck exists between electron and phonon baths, preventing full thermalization of electrons and phonons in graphene. This is especially important for the decay of electron–hole pairs excited with p-polarization. The type of scattering (electron–electron, electron–phonon or phonon–phonon) is indicated.
