Abstract
We proposed and fabricated resonant-tunneling-diode (RTD) terahertz (THz) oscillators with a structure for high-frequency direct modulation, which is useful for high-capacity THz wireless communications. The oscillator is composed of RTD and slot antenna. To obtain high cut-off frequency of direct modulation, the capacitance of the metal-insulator-metal (MIM) layer forming the slot antenna was reduced without decrease in THz output power which was a problem in the previous structure. A cut-off frequency of 30 GHz was obtained in direct intensity modulation of the device oscillating at 350 GHz with the reduced MIM capacitance of 0.7 pF.