Size Effects of Raman and Photoluminescence Spectra of CdS Nanobelts
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- 作者：Chuan Hu ; Xianghua Zeng ; Jieya Cui ; Haitao Chen ; Junfeng Lu
- 刊名：Journal of Physical Chemistry C
- 出版年：2013
- 出版时间：October 10, 2013
- 年：2013
- 卷：117
- 期：40
- 页码：20998-21005
- 全文大小：477K
- 年卷期：v.117,no.40(October 10, 2013)
- ISSN：1932-7455
文摘
Different sizes of CdS nanobelts were synthesized at 800, 850, and 900 掳C by the thermal evaporation of CdS powders on Au-coated silicon substrates and were used to study the size effects of Raman scattering and photoluminescent spectra. The Raman spectra of CdS nanobelts clearly exhibit first- and second-order longitudinal optical (LO) Raman peaks, surface phonon peaks, and multiphonon processes when excited using a wavelength of 532 nm. The mechanism of exciton鈥損honon coupling was observed to be mainly associated with the Fr枚hlich interaction, and the coupling strength of the exciton鈥損honon increases with increasing lateral size. Compared with a larger CdS nanobelt, a narrower nanobelt exhibits a larger tensile strain. Recombination of free excitons (FX), excitons bound to neutral impurities (A0X), and donor鈥揳cceptor pairs (DAP) were identified from a low-temperature PL spectrum. At temperatures below 123 K, a red shift of the FX energy occurs with decreasing lateral size due to a larger uniaxial tensile strain; at temperatures above 123 K, a red shift of the FX energy occurs with increasing lateral size because of the reabsorption of the emitted light inside the thicker belt, indicating that the FX energy is affected by both the tensile strain and the surface-depletion-induced quantum confinement (the reabsorption of the emitted light) in the nanobelt.