Our objective is to study Raman spectra from Ge-74 isotope enriched nc-Ge/amorphous-Ge structures, given the expected minimal influence of the matrix on the nanocrystalline phase in the structures with a modified isotope composition. We also assess the potential of plasma-enhanced chemical vapor deposition for producing germanium nanocrystals in the amorphous matrix from germanium tetrafluoride enriched with Ge-74 isotope. The nanocrystal phase was formed by annealing the samples in different conditions. The nc-Ge peak width and position in the Raman spectrum agree well with the theoretical data. The out-of-plane elastic strain of the nc-Ge lattice in the annealed structures, estimated from the shift of the Ge (111) and (220) diffraction peaks, was of the order of 1.10(-3). (C) 2013 Elsevier B.V. All rights reserved.