Submillimeter-Wave Oscillations in Recessed InGaAs/InAlAs Heterostructures: Origin and Tunability

Abstract

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 Γ valley electrons. In this work we explain the mechanism at the origin of this effect and also the influence of the bias conditions, δ-doping, recess-to-drain distance and recess length on the frequency of the ultrafast Gunn-like oscillations. The simulations show that a minimum value for the δ-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 the oscillation frequency, so provides an interesting frequency tunability of this THz source.