Optical metal-oxide tunnel detectors with microstructured electrodes

Order-of-magnitude improvement of the quantum efficiency of metal-oxide-metal detectors is achieved in the visible spectrum by fabricating the devices on silica substrates structured with a periodic array of bumps separated by about 0.25 microm. Structuring metallic films affords improved coupling of the detector to visible light by excitation of localized plasma resonances and surface-plasmon polariton modes. Voltage responsivities of 5 mV/W into a 50-Omega impedance has been demonstrated in preliminary devices. In suitable geometries, such detectors have the potential of subpicosecond response times.