Two-terminal devices as fundamental solid-state terahertz oscillators

The state-of-the-art radio frequency (RF) power levels at millimeter- and submillimeter-wave frequencies as well as the low-noise properties make GaAs tunnel injection transit-time (TUNNETT) diodes and InP Gunn devices prime candidates for fundamental solid-state terahertz oscillators. As examples, RF power levels of >130 mW at 132 GHz, >80 mW at 152 GHz, and >1 mW at 315 GHz were measured with InP Gunn devices, whereas RF power levels of 100 mW at 107 GHz and >10 mW at 202 GHz were measured with GaAs TUNNETT diodes. These experimental results as well as performance predictions for these devices at terahertz frequencies are reviewed and compared with the potential and the capabilities of other two-terminal devices such as impact avalanche transit-time (IMPATT) diodes and resonant-tunneling diodes (RTDs). The paper also summarizes advances in fabrication technologies as well as the application of more recent device principles and power-combining schemes.