Structural study of metastable (GaAs)(1-X)(Ge-2)(X) thin films grown by RFmagnetron sputtering

Epitaxial metastable (GaAs)(1-x)(Ge-2)(x) thin films have been grown on GaA s(1 0 0) in a RF planar magnetron sputtering system (MS), without As overpr essure, throughout most of the full compositional X range. The structural a nd compositional properties were investigated by high resolution X-ray diff raction (HRXRD) and secondary ion mass spectrometry (SIMS). The SIMS depth profiles demonstrate good homogeneity of Ge concentration for all the sampl es. HRXRD measurements show that the lattice constant dependence on the con centration X does not obey Vegard's law and that a transition between zinc- blende and diamond crystal structures occurs at X approximate to 0.35 (C) 1 999 Elsevier Science B.V. All rights reserved.