This work focuses on dipole antenna-coupled metal-oxide-metal diodes, which can be used for the detection of long wave infrared radiation. These detectors are defined using electron beam lithography and fabricated with shadow evaporation metal deposition. Along with offering complementary metal oxide semiconductor compatible fabrication, these detectors promise high speed and frequency selective detection without biasing, a small pixel footprint, and full functionality at room temperature without cooling. Direct current current-voltage characteristics are presented along with detector response to 10.6μm radiation. The detection characteristics can be tailored to provide for multispectral imaging in specific applications by modifying device geometries.
Directional control of received infrared radiation is demonstrated with a phased-array antenna connected by a coplanar strip transmission line to a metal-oxide-metal (MOM) tunnel diode. We implement a MOM diode to ensure that the measured response originates from the interference of infrared antenna currents at specific locations in the array. The reception angle of the antenna is altered by shifting the diode position along the transmission line connecting the antenna elements. By fabricating the devices on a quarter wave dielectric layer above a ground plane, narrow beam widths of 35° FWHM in power and reception angles of ± 50° are achieved with minimal side lobe contributions. Measured radiation patterns at 10.6 μm are substantiated by electromagnetic simulations as well as an analytic interference model.
Articles you may be interested inPrinted array of thin-dielectric metal-oxide-metal (MOM) tunneling diodes Thermal infrared detection using dipole antenna-coupled metal-oxide-metal diodes J. Vac. Sci. Technol. B 27, 11 (2009); 10.1116/1.3039684 Direct-write electron-beam lithography of an IR antenna-coupled microbolometer onto the surface of a hemispherical lensThe authors have designed a new procedure for fabrication of infrared ͑IR͒ sensors. These sensors consist of a dipole antenna coupled with a metal-oxide-metal ͑MOM͒ ͑Al-AlO x -Pt͒ diode. The surface of electron beam evaporated Al, serving as one of the electrodes, is cleaned using an Ar plasma, followed by in situ controlled growth of the tunneling oxide, AlO x . The antenna, its leads, and the overlap of the Al and Pt electrodes that defines the MOM overlap area are all defined using electron beam lithography. The MOM overlap area of these devices is as small as 50ϫ 80 nm 2 . Features of our process include the use of dissimilar metals for the formation of the MOM diode, small MOM diode size, and controlled etching and regrowth of the tunneling oxide. A CO 2 laser at 10.6 m was used for the IR characterization of these sensors. Current-voltage and IR measurements are presented. The normalized detectivity ͑D ء ͒ for these devices was found to be 2.13ϫ 10 6 cm Hz 1/2 W −1 .
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