Molecular beam epitaxy of ZnxBe1-xSe: Influence of the substrate nature and epilayer properties

We have studied the heteroepitaxial growth of ZnxBe1-xSe onto Si, GaAs and GaP substrates. By comparing the growth on these different substrates, we s howed that lattice-matching is not a sufficient condition to achieve a good epitaxy. Then we have investigated by low-temperature photoluminescence an d reflectivity spectroscopies a series of ZnxBe1-xSe alloys with Be content up to 70%. This allowed us to locate the direct-to-indirect band-gap cross over at x = 0.46. We found a bowing parameter b = 0.97 eV for the direct b and-gap in the whole composition range. Finally, Zn0.59Be0.41Se and Zn0.55B e0.45Se alloys lattice-matched, respectively, to GaP and Si substrates are direct band-gap semiconductors which exhibit band-gap at 3.72 eV and 3.85 e V.