Epitaxial growth of zinc blende MgS directly on GaAs (0 0 1) substrates

We report the epitaxial growth of zinc blende MgS directly on GaAs (0 0 1) substrates without the use of any II-VI buffer layer. MgS layers up to 35 nm thick were grown before conversion to the rocksalt phase is observed. The layers were grown by molecular beam epitaxy using significantly lower Mg fluxes than previously used and over a narrow temperature range of 230-255 degrees C. Analysis of the layers during and after growth shows very little difference between these and layers deposited conventionally on ZnSe buffers. In particular, the low Mg flux does not significantly alter the growth rate or residual Zn content. This point is discussed with respect to previous models of MgS growth.