STRUCTURAL AND OPTICAL-PROPERTIES OF ZN1-XMGXSE ALLOYS GROWN ON GAAS(001) SUBSTRATES BY MOLECULAR-BEAM EPITAXY

The Zn1-xMgxSe alloys for x up to 0.72 have been grown on GaAs(0 0 1) substrates by molecular beam epitaxy. For Zn-rich samples, the pure zi ncblende (0 0 1) structure is obtained. For Mg-rich films, however, bo th (1 1 1) and (0 0 1) domains coexist with the former having a lower x value as compared to the latter. Despite its very low content, the ( 1 1 1) domain has a profound contribution to the optical spectra, sugg esting that the (1 1 1) structure is more stable and has higher crysta l quality in the Mg-rich films when grown on GaAs(0 0 1) substrates. T he measured infrared reflection and photoluminescence spectra can only be understood well when the different structural phases in the films are properly considered. (C) 1998 Elsevier Science B.V. All rights res erved.