Magnetic modulation of low-temperature exciton-phonon coupling in ZnO nanowires

Abstract Exciton-phonon coupling is important for the optoelectrical properties of semiconductors, and it could be modulated by pressure, temperature, and lattice symmetry. Here we report the suppression of exciton-phonon coupling in ZnO nanowires by magnetic fields. ZnO and Fe-doped ZnO nanowires were grown by using chemical vapor deposition and their photoluminescence was measured in a wide temperature and magnetic field range. At cryogenic temperature the pure ZnO nanowires show various excitonic emission bands, while for the Fe-doped ZnO nanowires, the emission due to excitons coupled to the longitude optical phonons are suppressed. In a high magnetic field, the corresponding emission bands in the ZnO nanowires are also suppressed and the photoluminescence spectra become similar to that of the Fe-doped ZnO nanowires at zero field. The results indicate that magnetic doping could be an effective approach for modulation the exciton-phonon coupling.