INVERSION OF ELECTRON POPULATIONS IN STEPPED HETEROSTRUCTURES

The motion of electrons in stepped heterostructures was investigated i n fields corresponding to electron streaming. The distribution functio ns undergo an inversion in certain particular profiles and the degree of inversion is significantly greater than for homogeneous films. This effect offers the attractive possibility of creating active media bas ed on such heterostructures. By suitably choosing the heterostructure profile it is possible to ensure ballistic motion of electrons in rela tively thick heterostructures, which can be exploited to improve the r esponse time of semiconductor devices. (C) 1996 American Institute of Physics.