Optical properties of thin-film magnesium silicide prepared by electrochemical process

We report the optical properties of a thin-film Mg2Si, which was successfully prepared as a continuous and homogeneous polycrystalline phase on a Si(1 0 0) face by an electrochemical process with a thickness greater than 10μm. The growth rate achieved in the process was the order of 10μm/h. Optical absorption coefficient spectra obtained at room temperature exhibited an absorption edge at around 0.8 eV. Assignments of the peaks in the spectra to the optical transitions were based on using conventional reports. The absorption bands at 1.90 and 2.63 eV are consistent with the reported direct transitions in the reflectance measurements for single crystals and the results of band calculations. The absorption at the band edge, which is claimed to be an indirect transition from the calculations, contains a substantial direct absorption.