Molecular beam epitaxial growth and characterization of Be(Zn)Se on Si(001) and GaAs(001)

We have studied the heteroepitaxial growth of Be(Zn)Se alloys on both GaAs and Si substrates. The growth onto silicon shows many difficulties which ar e not completely solved yet. In contrast, on GaAs substrates, good crystall ine quality is obtained even for layers with lattice misfit as high as 4%. p-Type doping with N-A-N-D of 2 x 10(17) cm(-3) has been achieved fur Be0.1 7Zn0.83Se (E-a = 3.18 eV). The optical properties of these alloys have been investigated using reflectivity, photoluminescence and vacuum UV ellipsome try. Ellipsometric studies of BeSe grown onto Si supports the indirect natu re of the gap and confirms the position of the fundamental gap around 5.5 e V. The variation of the optical properties in BeZnSe alloys reveals the exi stence of a singularity around 46% which is attributed to a change in the b and-gap nature nature. (C) 2000 Elsevier Science B.V. All rights reserved.