Abstract
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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Leong, M.; Doris, B.; Kedzierski, J.; Rim, K.; Yang, M. Silicon device scaling to the Sub-10-nm regime. Science 2004, 306, 2057–2060.
Cao, J.; Ertekin, E.; Srinivasan, V.; Fan, W.; Huang, S.; Zheng, H.; Yim, J. W. L.; Khanal, D. R.; Ogletree, D. F.; Grossman, J. C., et al. Strain engineering and one-dimensional organization of metal-insulator domains in single-crystal vanadium dioxide beams. Nat. Nanotechnol. 2009, 4, 732–737.
Xu, S.; Qin, Y.; Xu, C.; Wei, Y. G.; Yang, R.; Wang, Z. L. Self-powered nanowire devices. Nat. Nanotechnol. 2010, 5, 366–373.
He, J.; Lilley, C. M. Surface effect on the elastic behavior of static bending nanowires. Nano Lett. 2008, 8, 1798–1802.
Zhang, Y. F.; Han, X. D.; Zheng, K.; Zhang, Z.; Zhang, X. N.; Fu, J. Y.; Ji, Y.; Hao, Y. J.; Guo, X. Y.; Wang, Z. L. Direct observation of super-plasticity of beta-SiC nanowires at low temperature. Adv. Funct. Mater. 2007, 17, 3435–3440.
Han, X. B.; Kou, L. Z.; Lang, X. L.; Xia, J. B.; Wang, N.; Qin, R.; Xu, J.; Liao, Z. M.; Zhang, X. Z.; Shan, X. D., et al. Electronic and mechanical coupling in bent ZnO nanowires. Adv. Mater. 2009, 21, 4937–4941.
Trauernicht, D. P.; Mysyrowicz, A.; Wolfe, J. P. Strain confinement and thermodynamics of free excitons in a direct-gap semiconductor. Phys. Rev. Lett. 1983, 28, 3590–3592.
Zhou, J.; Gu, Y. D.; Fei, P.; Mai, W. J.; Gao, Y. F.; Yang, R. S.; Bao, G.; Wang, Z. L. Flexible piezotronic strain sensor. Nano Lett. 2008, 8, 3035–3040.
Cross, L. E. Flexoelectric effects: Charge separation in insulating solids subjected to elastic strain gradients. J. Mater. Sci. 2006, 41, 53–63.
Raffaele, R. Towards a bulk theory of flexoelectricity. Phys. Rev. Lett. 2010, 105, 127601.
Ma, R. M.; Dai, L.; Qin, G. G. High-performance nano-Schottky diodes and nano-MESFETs made on single CdS nanobelts. Nano Lett. 2007, 7, 868–873.
Oulton, R. F.; Sorger, V. J.; Zentgraf, T.; Ma, R. M.; Gladden, C.; Dai, L.; Bartal, G.; Zhang, X. Plasmon lasers at deep subwavelength scale. Nature 2009, 461, 630–632.
Zhang, M.; Zhai, T. Y.; Wang, X.; Liao, Q.; Ma, Y.; Yao, J. N. Carbon-assisted morphological manipulation of CdS nanostructures and their cathodoluminescence properties. J. Solid State Chem. 2009, 182, 3188–3194.
Titova, L. V.; Hoang, T. B.; Jackson, H. E.; Smith, L. M.; Yarrison-Rice, J. M.; Lensch, J. L.; Lauhon, L. J. Low-temperature photoluminescence imaging and time-resolved spectroscopy of single CdS nanowires. Appl. Phys. Lett. 2006, 89, 053119.
Zhou, W. C.; Pan, A.; Li, Y.; Dai, G. Z.; Wan, Q.; Zhang, Q. L.; Zou, B. S. Controllable fabrication of high-quality 6-fold symmetry-branched CdS nanostructures with ZnS nanowires as templates. J. Phys. Chem. C 2008, 112, 9253–9260.
Smith, A. M.; Mohs, A. M.; Nie, S. M. Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain. Nat. Nanotechnol. 2009, 4, 56–63.
Niles, D. W.; Höchst, H. Strain-induced changes in the electronic valence-band structure of a cubic CdS(100) film. Phys. Rev. B 1991, 44, 10965–10968.
Wu, P. C.; Ye, Y.; Sun, T.; Peng, R. M.; Wen, X. N.; Xu, W. J.; Liu, C.; Dai, L. Ultrahigh-performance inverters based on CdS nanobelts. ACS Nano 2009, 3, 3138–3142.
Han, X. D.; Zhang, Y. F.; Zhang, X. N.; Zhang, Z.; Hao, Y. J.; Guo, X. Y.; Yuan, J.; Wang, Z. L. Low-temperature in situ large strain plasticity of ceramic SiC nanowires and its atomic-scale mechanism. Nano Lett. 2007, 7, 452–457.
Titova, L. V.; Hoang, T. B.; Jackon, H. E.; Smith, L. M. Low-temperature photoluminescence imaging and time-resolved spectroscopy of single CdS nanowires. Appl. Phys. Lett. 2006, 89, 053119.
Xu, J.; Chen, L.; Yu, L. S.; Liang, H.; Zhang, B. S.; Lau, K. M. Cathodoluminescence study of InGaN/GaN quantum-well LED structures grown on a Si substrate. J. Electron. Mater. 2007, 36, 1144–1147.
Soler, J. M.; Artacho, E.; Gale, J. D.; García, A.; Junquera, J.; Ordejón, P.; Sánchez-Portal, D. The SIESTA method for ab initio order-N materials simulation. J. Phys. Condens. Matter. 2002, 14, 2745–2779.
Bryant, F. J.; Radford, C. J. Electron radiation damage and the green edge emission of CdS. J. Phys. C: Solid State Phys. 1970, 3, 1264–1274.
Author information
Authors and Affiliations
Corresponding authors
Electronic supplementary material
Rights and permissions
About this article
Cite this article
Fu, Q., Zhang, Z.Y., Kou, L. et al. Linear strain-gradient effect on the energy bandgap in bent CdS nanowires. Nano Res. 4, 308–314 (2011). https://doi.org/10.1007/s12274-010-0085-6
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12274-010-0085-6