Monolithic high-power millimeter-wave quasi-optical frequency multiplier arrays using quantum barrier devices

GaAs barrier-N-N+ (BNN) diode arrays have been successfully designed and fabricated. Frequency doubling to 66 GHz has been achieved with an output power of 2.4-2.6 W and an efficiency in excess of 10%. In addition to the BNN arrays, a number of new device concepts have been developed in the course of this research which offer the promise of more efficient frequency multipliers with both higher cutoff frequency and higher power handling capability. These include the multi-quantum-barrier varactor (MQBV), and the Schottky-quantum-barrier varactor (SQBV). Measured C-V characteristics of the MQBV (4*20 mu m/sup 2/) show a C/sub max//C/sub min/ ratio of 5 with a C/sub min/ of 10 fF. In excess of 10 times reduction in thermionic current compared to the single-barrier device has also been obtained. The performance of the MQBV can be further improved by incorporating a Schottky-barrier structure on multi-quantum barriers to form the SQBV. The advantages SQBV has over the MQBV are discussed. A SQBV array with a Schottky-barrier structure in series with a yield of 99% (1300 devices), and an output power of 3.8-10 W with an efficiency of 1.7-4% at 99 GHz has been achieved.