Advances in GaAs Schottky diode submillimeter heterodyne receivers and radiometers

Radiometric sensitivity measurements were made on a quasi-optical receiver in the spectral range 170 micrometers to 1 mm. Using GaAs Schottky mixer diodes in a corner reflector configuration, a total system noise temperature of 9,700 K (DSB), or an NEP of 1.3 x 10 to the 19th power W/Hz, was obtained at 447 micrometers. This same quasi-optical mixer was also used for the generation of tunable harmonic and side-band radiation suitable for submillimeter spectroscopic applications. Planar, surface-oriented GaAs Schottky diodes were fabricated by means of photolithographic techniques in conjunction with ion implantation and proton bombardment. High-order harmonic mixing and direct heterodyne mixing with lasers up to 761 GHz were achieved. These planar diodes can be fabricated into array configurations by means of an integrated circuit approach.