Epitaxial germanidation of full-Heusler Co2FeGe alloy thin films formed by rapid thermal annealing

The authors demonstrated that a full-Heusler Co2FeGe (CFG) alloy thin film was epitaxially grown by rapid-thermal-annealing-induced germanidation of an Fe/Co/pseudo-Ge(001)-on-insulator (GOI) multilayer formed on a Si-on-insulator (SOI) substrate. X-ray diffraction (XRD) measurements with out-of-plane and in-plane configurations revealed that the CFG film was epitaxially grown along the [001] direction with the in-plane epitaxial relation of CFG[100]‖GOI[100], although the film slightly contained a non-epitaxial component. The strong (111) and (200) superlattice diffraction intensities indicated that the CFG film had a high degree of order for the L21 structure. Cross-sectional high-resolution transmission electron microscopy images of the film revealed that the film had dominant epitaxial and slight non-epitaxial components, which was consistent with the XRD measurements. The epitaxial component was grown directly on the buried oxide layer of the SOI substrate without formation of any interfacial layer.