Fabrication, Characterization, and Application of Heterogeneously Integrated GaAs Schottky Diodes
Nadri, Souheil, Electrical Engineering - School of Engineering and Applied Science, University of Virginia
Weikle, Robert, EN-Elec/Computer Engr Dept, University of Virginia
Gallium arsenide Schottky diodes remain the predominant device technology for implementing sources, detectors, and heterodyne-based components for instruments operating from 100 GHz to more than 4 THz. Developments in submillimeter-wave diode technology have been aimed at improving fabrication yields, lowering device parasitics which degrade the electrical performance, and improving thermal management. In this process, the geometry and implementation of GaAs diodes have evolved from a stand alone whisker contact device to a planar Schottky diode integrated with various passive circuit components. In 2015, Alijabbari developed an initial process for integrating quasi-vertical gallium arsenide Schottky diodes on silicon substrates. Using this process, a 40-160 GHz frequency multiplier source was implemented, exhibiting high frequency translation efficiency (29%) and large output power
(70 mW). However, the fabrication process suffered from low to modest yields. The focus of this thesis is to improve the fabrication process and assess the electrical and thermal characteristics of quasi vertical GaAs diode heterogeneously integrated on Si. The improved process eliminates thermal fabrication steps, including ohmic contact annealing and high-temperature wafer bonding, which lead to wafer fracture and delamination. After that, a new method for extracting diode parasitics based on measurements of passive open and short circuited structures, fabricated on the same wafer as the diodes, is presented. Furthermore, the thermal behavior of the quasi-vertical diodes is investigated for the first time using a thermo-reflectance measurement technique. Finally, the robustness of the new fabrication process is further assessed through the implementation of a WR-5 (140-220 GHz) quasi optical diode array.
PHD (Doctor of Philosophy)
Schotty diode, Heterogeneous integration, Terahertz, Submillimeter-wave, Fabrication, Array, Characterization
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