Ultrasensitive mid-IR photodetector based on hybrid graphene and phase-changing vanadium oxide heterostructure operating above room temperature

We present the model of an ultrasensitive mid-infrared (mid-IR) photodetector consisting of a hybrid heterostructure made of nanopatterned graphene (NPG) and vanadium dioxide (VO₂) which exhibits a large responsivity of exceeding R=10⁴ eV, a detectivity exceeding 10¹⁰, and a sensitivity in terms of noise-equivalent power (NEP) lower than 100 fW/sqrt(Hz) above room temperature by taking advantage of the phase change of a 3 nm thin VO₂ sheet. Our proposed photodetector can reach an absorption in the graphene sheet of nearly 100% due to localized surface plasmons (LSPs) around the patterned circular holes. The geometry of the nanopattern and an electrostatic gate potential can be used to tune the wavelength peak in the mid-IR regime between 3 and 12 microns. After the photon absorption by the NPG sheet and the resulting phase change of VO₂ the applied bias voltage V_b triggers a current through the VO₂ sheet, which can be detected electronically on a sub-ms timescale, much shorter than the detection time of typical VO₂ bolometers. Our proposed mid-IR photodetector reaches detectivities of cryogenically cooled HgCdTe photodetectors and sensitivities close to and field of view similar to VO₂ bolometers while operating above room temperature.