Transient electronic transport in staircase heterostructures

We present a Monte Carlo simulation of electronic transport in new forms of GaAs-GaAlAs heterostructures designed for achieving high drift velocities. Average electron speeds of ∼ 5.0 × 10⁷cm/s through an entire structure length of 0.5 µm have been calculated. This represents a marked improvement in speed over a single barrier emitter structure. The basic physical principle is the following: the electrons are confined to the gamma valley by losing excess kinetic energy gained from an overlaid accelerating field. The mechanism for the energy loss is a series of ascending potential steps. In this way transfer to the subsidiary minima is avoided and very high velocities are possible. Paradoxically, this means that because the electrons lose kinetic energy their velocity remains high or actually increases.