Strain-induced microstructural evolution in epitaxial Fe/MgO layers grown on InxGa1-xAs(001) substrates

Epitaxial Fe/MgO layers have been grown on InxGa1-xAs substrates to examine the epitaxial relationship and the morphological variation with respect to indium content, x and the growth temperature of MgO interlayer. The in-plane epitaxial relationship of Fe[010]//MgO[1 (1) over bar0]//InxGa1-xAs[1 (1) over bar0] is found in the structures of all x values for 4 nm thick MgO layers grown at room temperature. Epitaxial MgO interlayers grow in two-dimensional layer regardless of x while the morphology of subsequent Fe changes from two-dimensional layer to three-dimensional islands with the increase of x. Furthermore, the average size of Fe islands becomes smaller at higher x value due to enhanced underlying strain. The elevated growth temperature of MgO has led to partial strain relaxation, resulting in the suppression of three-dimensional Fe island formation. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3231075]