ESR studies on luminescent ZnS:Mn films and CdS [sbnd]ZnS:Mn superlattices deposited on a GaAs(100) substrate by hot-wall epitaxy

Abstract

Luminescent ZnS:Mn thin films and CdS-ZnS:Mn superlattices on a GaAs(100) substrate prepared by the hot-wall epitaxy technique have been examined by means of electron spin resonance (ESR) spectroscopy. It was observed that the lowest energy transition assigned toM 1 = −5/2 splits into either a triplet or a quintet (depending on the film thickness) when the magnetic field is applied normal to the films. Computer simulation clarified that there is no significant change in their hyperfine coupling constant and splitting parameters, while apparent differences in the ESR lineshape come from the change in linewidths of the fine structure involved. The linewidths for the transitionsM s = ±5/2↔ ±3/2 decrease markedly with increasing thickness of the ZnS:Mn film on the GaAs substrate. This phenomenon is explained in terms of uniaxial deformation of the crystal field surrounding manganese(II) due to lattice mismatch between the ZnS:Mn epitaxial layer and the GaAs substrate. For the CdS-ZnS:Mn superlattices, on the other hand, no angular dependence was observed, suggesting that the alignment of the ZnS:Mn layers sandwiched between the CdS layers is rather poor.