| This dissertation discusses the construction of a 1 x 5 heterodyne receiver array intended for operation at 1450 GHz. The receiver incorporates niobium superconducting hot-electron bolometer mixers and inexpensive waveguide components micromachined from silicon, and is intended to fly on a NASA mission called SOFIA (the Stratospheric Observatory for Infrared Astronomy). The mixers are fabricated on thin membranes of silicon nitride, which allows the array of devices to exist on a single silicon chip.; The hot-electron bolometer mixers examined during the course of this research are 100 A thick microbridges of niobium in intimate contact with thick, normally conducting gold pads at each end. The lateral dimensions of the microbridges are quite small (about 0.22 mum long by 0.10 mum wide, or less). These devices were fabricated individually using focused-ion beam pattern definition, and finished by inert argon ion etching of gold. This dissertation examines materials issues relating to the fabrication process, discusses the applicability of the focused-ion beam instrument to the patterning of small structures, and presents the measured characteristics of finished and passivated devices.; The yield of this fabrication process is quite high (perhaps more than 90%), and the HEB devices which result seem to be quite robust and stable. FIB-manufactured HEB devices possess I-V characteristics which are similar to those published in the literature for devices fabricated by other means (typically EBL), with the exception that they do not exhibit negative differential resistance or hysteresis (down to 4.2 Kelvins). The devices absorb 10 GHz radiation appropriately, and demonstration of their operation as terahertz hot-spot mixers is expected. |
