Linear strain-gradient effect on the energy bandgap in bent CdS nanowires
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- Fu, Q., Zhang, Z.Y., Kou, L. et al. Nano Res. (2011) 4: 308. doi:10.1007/s12274-010-0085-6
Although possible non-homogeneous strain effects in semiconductors have been investigated for over a half century and the strain-gradient can be over 1% per micrometer in flexible nanostructures, we still lack an understanding of their influence on energy bands. Here we conduct a systematic cathodoluminescence spectroscopy study of the strain-gradient induced exciton energy shift in elastically curved CdS nanowires at low temperature, and find that the red-shift of the exciton energy in the curved nanowires is proportional to the strain-gradient, an index of lattice distortion. Density functional calculations show the same trend of band gap reduction in curved nanostructures and reveal the underlying mechanism. The significant linear strain-gradient effect on the band gap of semiconductors should shed new light on ways to tune optical-electronic properties in nanoelectronics.
KeywordsStrain-gradient effect CdS nanowire bending deformation cathodoluminescence
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