Epitaxial Cu-Sn bulk crystals grown by electric current

摘要

Epitaxial Cu_3Sn and Cu_6Sn_5 grown by liquid-phase electroepitaxy (LPEE) have been demonstrated in this work. X-ray diffraction analysis reveals that LPEE-grown Cu_3Sn and Cu_6Sn_5 grew in particular directions (planes) with respect to the electron flow. LPEE-grown Cu_3Sn grew in the (020) and (400) directions, and LPEE-grown CugSris grew in the (204) and (6 2 3) directions. With the aid of a molecular simulation software tool, we conclude that the particular growth directions represent the low-resistance paths for electron flow. This means that, along those particular directions in the LPEE-grown Cu-Sn compounds, the traveling electrons would be scattered least by the lattice. Thus, as the electromigrating Cu atoms form Cu-Sn compound, the newly forming Cu-Sn unit cells would orientate themselves in those particular growth directions to facilitate electron flow. Then, the well-oriented newly formed Cu-Sn compound unit cells can incorporate the growth of the highly orientated LPEE-grown Cu-Sn compounds. In addition, the anisotropy of a number of properties of LPEE-grown Cu3Sn and Cu_6Sn_5, i.e. coefficient of thermal expansion, Vickers microhardness and electrical properties (resistivity, carrier mobility and carrier concentration), along the particular orientations were measured and reported.