IR absorption and Raman spectra of single crystals of stable germanium isotopes

摘要

The Raman and IR absorption spectra of single crystals of germanium isotopes Ge-72, Ge-73, Ge-74, and Ge-76 in the region of phonon absorption and interband electronic transitions are studied at room temperature. The dependence of the Raman peak position on the atomic mass has the form M (-1/2). The shifts of the phonon absorption peaks of individual isotopes with respect to germanium of natural isotopic composition Ge-nat are determined. With increasing average atomic mass of germanium, these peaks shift to longer wavelengths. In the region of interband electronic transitions, the intrinsic absorption edge of Ge-76 is observed to shift by 1 meV to higher energies with respect to Ge of natural isotopic composition. For isotopes with atomic masses close to that of natural germanium (Ge-72,Ge-73, Ge-74), we found no significant difference in the band gap width at room temperature.