Abstract:
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Successful experiments have demonstrated ballistic transport at room
temperature. From the application point of view, it is highly desirable
that new types of ballistic devices are capable of operating at room
temperature. At room temperature, the electron mean-free path in a III–V
semiconductor heterostructure is typically from 100 to 200 nm. Device
dimensions smaller than or at least comparable to le at T = 300 K are
therefore required. This is, however, very difficult if using a
GaAs–AlGaAs heterostructure due to the large depletion length (around
100 nm) close to the etched device boundary. The much shorter depletion
length (below 30 nm) in, for example, InGaAs–InAlAs or InGaAs–InP
material systems, makes it possible to fabricate much smaller devices that 
work at room temperature.