Growth and optical characterization of diluted magnetic semiconductor Zn1−xMnxSe/ZnSe strained-layer superlattices

Abstract

Zn 1−x Mn x Se/ZnSe strained-layer superlattices are grown by molecular beam epitaxy on GaAs(100) substrates and characterized by x-ray diffraction and low temperature photoluminescence. For the case where the total thickness of a Zn1−xMnxSe/ZnSe superlattice is well below the critical value, the structure grows pseudomorphically to the buffer layer. A blue shift of 6 meV of the excitonic peak is observed and has been explained by the carrier confinement effect only. For the case of a Zn1−xMnxSe/ZnSe superlattice with a thickness larger than its critical values, we show that it can be treated as free-standing with ZnSe under tension and Zn1−xMnxSe under compression. The strain present can overwhelm the quantum confinement to produce a net red shift of 2 meV of the near band-edge feature. The energy shifts due to the strain and quantum confinement are calculated on the basis of deformation potential theory and Bastard’s method, showing good agreement with the experimental results.