Semiconductor device with heterojunction of Al.sub.x Ga.sub.1-x As--AlAs--G a

The disclosure is directed to a semiconductor device comprising an active region between a pair of injecting/collecting layers, the active region comprising at least one layer of a first binary semiconductor material disposed between coupling barriers of a second different binary semiconductor material that is lattice matched to the first binary semiconductor material. In a preferred embodiment the active region comprises one or more layers of gallium arsenide separated by aluminum arsenide barrier layers.