Fabrication of epitaxial Cu₃Ge on sapphire with controlled crystallinity and planar defects

In this paper, we report the growth of epitaxial Cu₃Ge thin films on c-plane sapphire substrate through domain matching epitaxy. Systematic study on the crystallinity of Cu₃Ge thin films is carried out to correlate epitaxial characteristics with substrate lattice misfit. The crystallinity and epitaxy of the as-grown Cu₃Ge thin films are improved considerably by controlling the parameters of pulsed laser deposition. The epitaxial characteristics and formation of twins in Cu₃Ge are investigated and a mechanism of twin formation in Cu₃Ge ε₁-phase is discussed. The present study proves that the crystallinity and defect structure of Cu₃Ge thin film can be controlled by adjusting the deposition parameters. It serves as a fundamental research for future applications of epitaxial Cu₃Ge as metallization material in semiconductor industry.