Recently, arrays of subwavelength slits or holes in metal films have attracted a lot of interest due to the anomalously high transmission of light. The properties of the transmission resonances can be controlled by the periodicity and the width and height of the slits/holes in the array. Our aim is to employ the plasmonic effects in the design of metal-semiconductor-metal (MSM) photodetectors and light emitting diodes. Using the interaction between light and plasmonic resonances in periodically structured metals allows to overcome the effect of shading of the active device area which is the major drawback of metallic top electrodes. With this approach an efficient and homogeneous injection and extraction of the carriers in the devices should be achievable. In MSM detectors with interdigitated electrodes forming a 1D metallic grating, additionally the carrier drift time in the semiconductor structure below the electrodes is decreased and high speed response can be obtained. As the localized plasmons in 1D metallic gratings can be excited only by light polarized perpendicular to the slits (TM polarization) the properties of such devices will be polarization dependent. To model the properties of multilayered patterned structures with dispersive components we use the scattering matrix method. Fig. 1 shows the calculated transmission spectra of a structure consisting of a GaAs/AlAs waveguide on a GaAs substrate and a 1D gold grating on top (cf. inset). As the metal thickness is increased the transmission is increasing, reaching a maximum of 95% at a photon energy of 1345 meV for a thickness of 170 nm.
展开▼
