We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal （Au/Al2O3/graphene） heterostructure. In this device, hot electrons, excited optically in the gold layer, jump ov...We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal （Au/Al2O3/graphene） heterostructure. In this device, hot electrons, excited optically in the gold layer, jump over the oxide barrier and are injected into the graphene layer, producing a photocurrent. To amplify this process, the bottom gold electrode is patterned into a plasmon resonant grating structure with a pitch of 500 nm. The photocurrent produced in this device is measured using 633-nm-wavelength light as a function of incident angle. We observe the maximum photocurrent at ＋10° from normal incidence under irradiation with light polarized parallel to the incident plane （p-polarization） and perpendicular to the lines on the grating, and a constant （angle-independent） photocurrent under irradiation with light polarized perpendicular to the incident plane （s-polarization） and parallel to the grating. These data show an amplification factor of 4.6× under resonant conditions. At the same angle （±10°）, we also observe sharp dips in the photoreflectance corresponding to wavevector matching between the incident light and the plasmon mode in the grating. In addition, finite-difference time-domain simulations predict sharp dips in the photoreflectance at ±10°, and the electric field intensity profiles show clear excitation of a plasmon resonant mode when illuminated with p-polarized light at this angle.展开更多
文摘We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal （Au/Al2O3/graphene） heterostructure. In this device, hot electrons, excited optically in the gold layer, jump over the oxide barrier and are injected into the graphene layer, producing a photocurrent. To amplify this process, the bottom gold electrode is patterned into a plasmon resonant grating structure with a pitch of 500 nm. The photocurrent produced in this device is measured using 633-nm-wavelength light as a function of incident angle. We observe the maximum photocurrent at ＋10° from normal incidence under irradiation with light polarized parallel to the incident plane （p-polarization） and perpendicular to the lines on the grating, and a constant （angle-independent） photocurrent under irradiation with light polarized perpendicular to the incident plane （s-polarization） and parallel to the grating. These data show an amplification factor of 4.6× under resonant conditions. At the same angle （±10°）, we also observe sharp dips in the photoreflectance corresponding to wavevector matching between the incident light and the plasmon mode in the grating. In addition, finite-difference time-domain simulations predict sharp dips in the photoreflectance at ±10°, and the electric field intensity profiles show clear excitation of a plasmon resonant mode when illuminated with p-polarized light at this angle.
