Structure and Morphology of MBE Fabricated Zn0.5Fe0.5Se On GaAs as a Function of Substrate Preparation and Growth Temperature

Abstract

AbstractWe have recently reported the observation of CuAu-I, CuPt, and Cu3Au ordered structures in the diluted magnetic semiconductor Zn1−xFexSe grown by molecular beam epitaxy for different values of the Fe concentration. In the present work, we grew a series of samples with identical Fe composition (x=0.5) but for a range of growth temperatures (from 250 °C to 450 °C). By using transmission electron microscopy, ordering along the <001> and <110> directions was observed in both electron diffraction patterns and cross-sectional high-resolution lattice images corresponding to the CuAu-I ordered structure of Zn0.5Fe0.5Se. However, this ordered structure coexists with a tetragonal FeSe structure and forms large, well defined faceted domains. At the higher growth temperature, the number of faceted domains increases as observed by atomic force microscopy. Pure FeSe films were also grown at different temperatures for comparison. The influence of substrate preparation before film growth is also discussed.