Submillimeter-Wave Quasi-Vertical GaAs Schottky Diodes Integrated on Silicon Membranes

GaAs Schottky diodes are the central component of Terahertz (THz) metrology instrumentation. The frequency translating property of the Schottky diode is used in ground and space based observatories and for characterization of other THz devices. As detectors, GaAs Schottky diodes are used for measuring signal power levels, as mixers they are used in heterodyne receivers, and as variable capacitors they are used in frequency multipliers.
The focus of this dissertation is the integration of GaAs Schottky diodes on silicon-on-insulator (SOI) substrate carriers to better control the device parasitics and to accommodate assembly of fully integrated diode-based circuits. During research into this process, a unique quasi-vertical diode geometry was developed in which the ohmic contact lies directly below the Schottky anode. While similar in concept to the first whisker contacted Schottky diodes, the quasi-vertical diode is nevertheless a planar device that is readily integrated with other components supported by the SOI substrate, including beamleads for electrical connection. To illustrate the advantages of this technology, 40-to-80 GHz doublers and a new 40-to-160 GHz quadrupler were designed and implemented using the quasi-vertical diodes and heterogeneous integration methods developed in this research. These multipliers are the first demonstrated fully-integrated GaAs varactor circuits fabricated on SOI, yielding record performance in multiplication efficiency, and demonstrating the benefits of the novel diode architecture and substrate replacement technology.