Fundamental oscillation up TO 831 GHz in GaInAs/AlAs resonant tunneling diode

A fundamental oscillation of up to 831 GHz was observed at room temperature in GaInAs/AlAs resonant tunneling diodes integrated with planar slot antennas. The thickness of the collector spacer layer was optimized (20 nm) and the mesa area (<1 mum²) was reduced in order to reduce the resonant tunneling diode capacitance. Reduction in the negative differential conductance in the small mesa area was prevented by increasing the emitter doping concentration (3 times 10¹⁸ cm^-3) which resulted in an ultra-high peak current density (18 mA/mum²) with a peak-to-valley current ratio of 2. The dependence of oscillation frequency on the mesa area was also studied. The output power was at least 1 muW.