The effects of isotope disorder on the energies of the transverse acoustic (TAL), longitudinal acoustic (LAL) and transverse optical (TOL) phonons at the L point have been investigated using the luminescence of excitons bound to copper acceptors. In a sample with approximately equal 70Ge and 78Ge the TOL phonon is 0.14+or-0.03 meV higher in energy than expected for a crystal of the same mean atomic mass, while the LAL phonon is 0.07+or-0.03 meV lower in energy; the TOL phonon is also broadened by 0.4 meV. In this disordered sample the Cu no-phonon line is 0.05+or-0.02 meV higher than expected.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry