MBE growth and properties of bulk BeCdSe alloys and digital (BeSe : CdSe)/ZnSe quantum wells

We report for the first time on MBE growth, structural and optical properti es of single layers, quantum well structures and short-period superlattices based on BexCd1-xSe ternary alloys on GaAs. Both the conventional MBE grow th mode and the sub-monolayer digital alloying technique (SDA) have been em ployed for the fabrication of the structures. Compositional boundaries of a n instability region 0.03 < x < 0.38, calculated in a regular solution appr oximation for the completely coherent system, agree well with available exp erimental data. A suppression of the phase separation in BcCdSe by elastic stress in the layer, accompanied by a strong reduction of the Cd incorporat ion coefficient has been found. Ultrathin 2.8 ML BcCdSe SDA QWs with x simi lar to 0.15 demonstrate about an order of magnitude increase in the PL inte nsity with respect to the pure CdSe one, probably resulting from an enhance d carrier localization efficiency. E-g as a function of the Be content reve als a strong bowing in optical data, which allows one to consider BeCdSe al loys with compositions nearly lattice-matched to GaAs as potential material s for the active region of blue-green lasers. (C) 2000 Elsevier Science B.V . All rights reserved.