Integrated planar gallium arsenide Schottky mixers for submillimeter wavelength receivers.

摘要

Two integration technologies have been investigated. The first is the quartz upside-down inverted device (QUID) technology invented at JPL. Through this research QUID mixers operating at 240 GHz were fabricated and tested, thereby demonstrating the technology using UVa fabrication equipment and processes. A major drawback of the QUID integration process is that a layer of epoxy is used to adhere the diodes an metal films to the quartz. This epoxy is lossy and suffers from reliability concerns related to long term robustness and out-gassing. Through this research, the QUID process was extended to include a new etch step which removes the epoxy from all areas of circuit except between the quartz substrate and the attached layers. This resulted in the best published planar mixer sensitivity in the 200 to 300 GHz frequency range. This process was also transferred to JPL, where it helped improve the bandwidth of their 640 GHz mixers to meet the requirements of NASA's EOS-MLS mission.;The new etch process does not remove the layer of epoxy that is trapped in the critical region between the anode/finger and the quartz substrate. To avoid this concern, a new fabrication process was developed. The Method of Adhesion by Spin-on-dielectric Temperature Enhanced Reflow (MASTER) uses a novel semiconductor to substrate bonding process to eliminate the necessity of epoxy bonding. This process was fully developed and integrated mixers were fabricated for 585 GHz, 640 GHz, and 1 THz. The 585 GHz mixers were fully designed using computer modeling tools, were extremely easy to assemble, and most importantly exhibited record performance, Tsys = 1631 K, T mix = 1135 K, Lmix = 6.5 dB (all DSB). This result was accomplished without the use of mechanical tuning elements and was consistent for four assembled mixers, showing an unprecedented level of repeatability.;Through this dissertation research a new semiconductor on quartz integration technology has been created. This technology was demonstrated through the design, fabrication, and testing of a 585 GHz integrated mixer that is the most sensitive room temperature mixer ever reported for operation above 500 GHz. It is also the first planar mixer to outperform the best whisker contacted components in this frequency range. In addition to improved sensitivity, the new integrated technology offers greater bandwidth without reliance on mechanical tuners, a simplified design process, easier assembly, and drastically improved repeatability. As this integration technology is applied to mixers and multipliers throughout the terahertz range, it will significantly improve performance and reduce costs. Thus, this research has made an important contribution toward the creation of a commercially viable terahertz technology base. (Abstract shortened by UMI.)