Uniaxial tensile strain and exciton-phonon coupling in bent ZnO nanowires

We investigate the optical property of bent ZnO nanowires (NWs) obtained by low energy argon ion milling. At room temperature, the bent NWs demonstrates an enhanced near band edge ultraviolet emission, while the deep level green emission is totally suppressed. Temperature dependent photoluminescence measurements were carried out between 10 and 300 K for both the as-grown and the bent ZnO NWs. It is found that the emission peak energy of the bent NWs systematically shifts to lower energy compared to the as-grown NWs in the whole measured temperature range. Our results indicate that the redshift in the emission peak is related to the uniaxial tensile strain and the enhanced exciton-phonon coupling strength in the bent ZnO NWs.