GROWTH BY MOLECULAR-BEAM EPITAXY AND MAGNETOOPTICAL STUDIES OF (100)-ORIENTED AND (120)-ORIENTED DIGITAL MAGNETIC QUANTUM-WELL STRUCTURES

We report on growth by molecular beam epitaxy and magnetooptical inves tigations of digital alloys of diluted magnetic semiconductors. The di gital alloys, i.e., very short-period superlattices, of interest here, were grown from nonmagnetic CdTe and magnetic Cd1-xMnxTe. In particul ar, quantum well structures containing the digital alloys in the regio ns of the quantum wells were fabricated. We searched for theoretically expected modifications of magnetic properties of digitally grown mate rials compared to those of random substitutional alloy counterparts, W e monitored the magnetic behavior in our samples by studying their mag netooptical properties, We detected clear differences between magnetiz ations in random and digital alloys in samples grown along the [100] c rystallographic direction. Unexpectedly, no modification of the spin-s plitting (and, thus, of the magnetization) were observed in the case o f digital quantum wells grown in the [120] crystallographic direction. On the other hand, exciton magnetic polaron binding energy in the lat ter structures was consistently greater by 10-20% than this quantity i n similar samples grown along the [100] direction. The increase can be qualitatively understood in terms of the heavy hole mass anisotropy. (C) 1997 Elsevier Science S.A.