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The influence of surfaces and interfaces on coherent phonons in semiconductors |
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| Authors: | C -K Sun J C LiangS P DenBaarsD S Kim Y D ChoG D Sanders J SimmonsC J Stanton |
| Institution: | 1. College of Materials Science and Engineering, Nanjing Tech University, Xinmofan Road 5, Nanjing 210009, China;2. Jiangsu Collaborative Innovation Center for Advanced Inorganic Functional Composites, Nanjing Tech University, Xinmofan Road 5, Nanjing 210009, China;1. School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, NSW 2522, Australia;2. The State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819, China;3. Research Institute, Baoshan Iron and Steel Co., Ltd., Shanghai 201900, China |
| Abstract: | Experiments have shown that ultrafast optical excitation of semiconductors can produce oscillating changes in the optical properties of the material. The frequency of the oscillations in transmission or reflection usually matches one of the phonon modes, typically theq = 0 optical mode. These oscillations are known as coherent phonons. We discuss the role of surfaces and interfaces on the coherent phonon signal. We show that: (1) the coherent phonon signal can be used as a probe of the surface depletion field and (2) multiple interfaces as in a superlattice, can drastically alter the coherent phonon spectrum: screening of the modes in the superlattices is reduced and acoustic modes can now be excited. |
| Keywords: | coherent-phonons superlattices ultrafast excitations |
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