QW-SHAPE-DEPENDENT HOT-ELECTRON VELOCITY FLUCTUATIONS IN INGAAS-BASEDHETEROSTRUCTURES

Hot-electron microwave noise was measured for InAlAs/InGaAs/InAlAs/InP quantum well channels containing two-dimensional electron gas subject ed to high electric field applied parallel to the heterojunctions. The shape of the well was controlled by doping and InGaAs composition. A quasitriangular well was formed by using a plane of donors located in the InAlAs barrier. A quasi-rectangular well was obtained by locating two planes of the donors on both sides of the well. A strong dependenc e on the well shape is observed at high electric fields (over 2 kV/cm) . The results are interpreted in terms of real-space transfer fluctuat ions.