SUBMILLIMETER-WAVE OSCILLATIONS IN RECESSED InGaAs/InAlAs HETEROSTRUCTURES: ORIGIN AND TUNEABILITY

By means of an ensemble Monte Carlo simulator, the appeareance of THz oscillations in InAlAs/InGaAs slot diodes is predicted when the applied bias exceeds the threshold for intervalley transfer. Such high frequency is attained by the presence of a Gunn-like effect in the recess-to-drain region of the device channel whose dynamics is controlled by ballistic  valley electrons. In this work we explain the mechanism at the origin of this effect and also the influence of the bias conditions, doping, recess-to-drain distance and recess length on the frequency of the ultra-fast Gunn-like oscillations. The simulations show that a minimum value for the -doping is necessary to have enough carrier concentration under the recess and allow the oscillations to emerge. Finally, we show that shortening the devices (small recess and recess-to-drain lengths) increases of the oscillation frequency, so providing an interesting frequency tuneability of this THz source. PACS numbers: 85.30.Fg, 07.57.Hm, 73.40.Kp