EXCITONIC EMISSION ENHANCEMENT BY DIRECTIONAL CARRIER INJECTION IN A ZNSE ZN0.78CD0.22SE MULTI-SUPERLATTICE/

Vertical photocurrent in a ZnSe/Zn0.78Cd0.22Se structure consisting of three sequent superlattices with 2.0, 3.8 and 8.2 nm well width was i nvestigated. At 77 K, only the superlattice with the 2 nm wells remain ed thermally activated. By means of excitation spectroscopy, we have d emonstrated that those thermally activated carriers performed a carrie r injection into the superlattices with the wider wells causing a sign ificant enhancement of their excitonic emission. We call the phenomeno n of carrier injection from a narrow superlattice into a wider one, di rectional carrier injection. (C) 1997 Published by Elsevier Science Lt d.