Fundamental oscillations at ~900 GHz with low bias voltages in RTDs with spike-doped structures

Fundamental oscillations are demonstrated at around 900 GHz with low bias voltages in resonant tunnelling diodes (RTDs) having spike-doped structures. Voltages at the current peak are 0.67 and 0.4 V for RTDs with spike-doping concentrations of 2×1018 and 1×1019 cm−3, respectively, and 0.94 V for the RTD without spike doping. The peak current densities are around 18 mA/µm2 and remain almost unchanged even after spike doping. The highest oscillation frequency observed in this study is 898 GHz in the 0.53 µm2 mesa area for the RTD with a spike-doping concentration of 2×1018 cm−3.