Submillimeter-wave InP Gunn devices

Recent advances in design and technology signifi- cantly improved the performance of low-noise InP Gunn devices in oscillators first at -band (110–170 GHz) and then at -band (75–110 GHz) frequencies. More importantly, they next resulted in orders of magnitude higher RF output power levels above -band and operation in a second harmonic mode up to at least 325 GHz. Examples of the state-of-the-art performance are continuous-wave RF power levels of more than 30 mW at 193 GHz, more than 3.5 mW at 300 GHz, and more than 2 mW at 315 GHz. The dc power requirements of these oscillators compare favorably with those of RF sources driving frequency multiplier chains to reach the same output RF power levels and frequencies. Two different types of doping profiles, a graded profile and one with a doping notch at the cathode, are prime candidates for operation at submillimeter- wave frequencies. Generation of significant RF power levels from InP Gunn devices with these optimized doping profiles is predicted up to at least 500 GHz and the performance predictions for the two different types of doping profiles are compared.