Monolithic Schottky diode imaging arrays at 94 GHz

Monolithic GaAs Schottky diode imaging arrays have been demonstrated at 69 and 94 GHz. In the 94 GHz experiments, the diodes are fabricated by a self-aligning technique on semi-insulating GaAs and are isolated by a combination of a mesa-etch process and proton-bombardment. The series resistance is 20 ω and the estimated capacitance is 15–20 fF. The antennas are planar bow-ties, and power is coupled in through a quartz lens placed on the back of the GaAs substrate. The wafer is lapped to 90 μm thick to eliminate losses to substrate modes. The measured system responsivity is 330 V/W. The 69 GHz diodes are made by a non-self-aligned process, and a silicon substrate lens is used.