INVESTIGATION OF STRAIN IN II-VI SEMICONDUCTOR SUPERLATTICES USING ELECTRON-PARAMAGNETIC-RESONANCE OF MN++

We explore the possibility of using electron paramagnetic resonance (EPR) of Mn++ for measuring uniaxial strain in II-VI superlattices. This work is motivated by the fact that the EPR spectrum of Mn++ is very strongly affected by crystalline fields. Changes in a crystalline field which arise from strain are thus automatically expected to have a profound effect on the EPR spectrum. Consistent with this expectation, we have observed giant crystal field splittings of Mn++ EPR lines in ZnTe/MnTe, CdTe/MnTe, and ZnTe/MnSe superlattices. The EPR spectra observed in these systems are ascribed to isolated Mn++ ions diffused into the ZnTe or the CdTe layers from the respective MnTe or MnSe layers. In addition to providing precise information on the magnitude and the sign of strain produced by lattice mismatch between the superlattice constituents, we show that the EPR spectrum also provides a direct measure of strain fluctuations in the layered medium.