Frequency increase in resonant-tunneling-diode terahertz oscillator by reduction in conduction loss with thick antenna electrode

Abstract

We obtained frequency increase in resonant-tunneling-diode (RTD) terahertz (THz) oscillators by thick antenna electrode. The THz oscillator was composed of an RTD and slot antenna. Because an oscillation at resonance frequency of the RTD and slot antenna occurs when the negative differential conductance of the RTD compensates for the loss of the antenna, a reduction in the conduction loss and inductance of slot antenna by thick antenna electrode is effective for high frequency oscillation. We obtained ∼150 GHz frequency increase after deposition of 1-µm-thick additional gold metal on 0.1-µm-thick antenna electrode. The highest oscillation frequency obtained in this experiment was 1.63 THz for 9-µm-long antenna and 0.22-µm2-area RTD. Theoretical calculation agreed well with the experiment, and an oscillation above 2 THz is expected by this structure and low capacitance RTD with thick spacer thickness.