Graphene-Based Field-Effect Photodetector with HgCdTe Absorber

A field-effect photodetector structure composed of an Al 2 O 3 -encapsulated bilayer graphene conductive channel attached to an Al 2 O 3 dielectric layer deposited on a HgCdTe absorbing layer on CdTe/Si <211> was studied. Ti/Au ohmic contacts to the graphene layer were used as drain and source electrodes and back-gate voltage was applied to the Si substrate. It was demonstrated that 80% and 10% modulation of the graphene channel conductivity can be achieved under blue (50 W/cm 2 ) and infrared (IR) (0.02 W/cm 2 ) illumination, respectively, at a gate voltage of 7 V. Detector responsivity was measured as 406 A/W and 1.83 A/W under IR lamp and 405-nm laser irradiation, respectively, with corresponding gain values of 340 and 5.6. The detectivity of the 4 × 4 photodetector arrays was on the order of 10 10 Jones for the mid-wave infrared wavelength range (3–5 μm).