Strain-free, ultra-high purity ZnSe layers grown by molecular beam epitaxy

Abstract

ZnSe layers have been grown by molecular beam epitaxy on high-purity, high-quality ZnSe wafers [(100) oriented] cut from ingots grown by the iodine vapor transport method. Photoluminescence (PL) analysis indicates the homoepitaxial ZnSe material to be of ultra-high purity as well as being strain-free relative to ZnSe/(100) GaAs layers which exhibit in-plane biaxial tension. The 10 K PL spectra recorded from homoepitaxial layers exhibit unsplit free- and donor-bound exciton transitions of comparable intensity together with a strong peak at 2.7768 eV believed to be the so-called Iv transition in relaxed ZnSc. The ultra-high purity nature of the homoepitaxial layers is attributed to the high purity of the substrate material in addition to the use of high purity Zn and Se source materials in this work.