Since the 1960s, metal-insulator-metal (MIM) tunneling diodes have been used for detecting and mixing electromagnetic waves up to infrared frequencies. To improve the wave coupling efficiency, an antenna is usually integrated with a MIM diode, and this integrated structure is known as a “rectenna” which can rectify incident waves. Although antenna coupled MIM diodes can detect and rectify infrared waves, the energy conversion efficiency of these structures is usually very low largely because of the response time of the tunnel junction. This thesis summarizes an attempt to improve the power conversion efficiency of the rectenna. As a result, novel tunneling diodes have been developed using a geometric field enhancement (GFE) technique, which takes advantage of the “lightning rod” effect. The GFE technique is implemented by using a pointed electrode, creating an asymmetric electric field in the region of the tunnel barrier. Thus, the tunneling current in this system can be asymmetric with respect to the sign of the applied bias. Furthermore, the geo metric structure of these novel optical rectennas provides the appropriate conditions for the excitation of surface plasmon resonances. These resonances further enhance the junction’s electric field, allowing for larger current flow, effectively lowering the diodes tunneling resistance.
Three different types of tunneling diodes are developed and explored in this research: a perfect planar type tunneling diode, an asymmetric tunneling diode (ATD), and a focused asymmetric metal-oxide-metal (FAMIM) tunneling diode. The fabrication processes for each new tunneling diode have been successfully developed. The degree of performance improvement achieved by each process is summarized. This thesis documents the highest MIM detection sensitivities of 31 V-1 and 22 V -1 reported in open literature for planar type tunneling diodes and ATDs, respectively. Improvements in tunneling current nonlinearity (curvature of the current-voltage plot) of 350 % and 33 % are achieved for ATDs and FAMIM diodes, respectively.
|School||UNIVERSITY OF MARYLAND, COLLEGE PARK|
|Subjects||Engineering; Electrical engineering|
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