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Phonon and vibrational spectra of real crystals obtained using the synchrotron radiation

Eugen M. Sheregii 1J Cebulski 1Jacek Polit 1B V. Robouch 2Augusto Marcelli 2M Piccinini 2A Kisiel 3Andrzej Mycielski 4

1. University of Rzeszow, Institute of Physics, Rejtana 16, Rzeszów 35-310, Poland
2. °Laboratori Nazionali Frascati INFN (INFN), Via E. Fermi 40, Frascati 00044, Italy
3. Jagiellonian University, Institute of Physics (IF UJ), Reymonta 4, Kraków 30-059, Poland
4. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland

Abstract

Data of measurements of optical reflection obtained in wide range of wave numbers (30 – 8000 cm-1­) in far and middle infrared regions and at temperatures (20 – 290 K) with using of synchrotron radiation have been summed up in given paper for the CdTe, CdHgTe, ZnHgTe, ZnCdTe and ZnCdHgTe crystals produced by different methods. An unique ownership of the synchrotron radiation have allowed to resolve subtle structure of the phonon and vibrational bands in researched crystals. The main results can be summarized as following: 1) in case of CdTe crystals different lines corresponding to the local mode were observed; additional lines associated with red shift with respect to the main phonon mode of the heavily hydrogenated CdTe were interpreted as a resonant or Additional Phonon Modes (APM) caused by the Cd-Te oscillations in tetrahedra containing one or two additional H atoms[1]; 2) in case of ZnCdTe crystals eight phonon modes, canonical for ternary alloys (canonical phonon mode – CPM) generated by defect free tetrahedra, were observed and successfully interpreted [2]; 3) in case of CdHgTe crystals phonon spectra can not be interpreted without taking into account intrinsic defects for n- and p-type of materials: tetrahedra containing the Hg-vacancies generate APM[3]; 4) similar situation is observed in ZnHgTe-crystals; 5) in case of quaternary ZnCdHgTe generally, we could observe 30 CPMs but really it is possible to resolve 10 - 15 ones to which it is necessary to add APMs caused by defect-bearing tetrahedra [4]. A statistical model of deformed tetrahedra was developed for quantitative analysis of observed spectra. [1] J.Polit, E.M.Sheregii, et al. J. Appl. Phys., 100, 013521, 2006; [2] J.Polit E.M.Sheregii et. al. Journal of Alloys and Compounds, 371, 172, 2004; [3] J.Polit, E.M.Sheregii et.al. Eur. Phys. J. Appl. Phys, 27, 321, 2004; [4] E.M. Sheregii, J.Polit et.al. Infrared Physics & Technology 49, 13, 2006;

 

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Presentation: Oral at E-MRS Fall Meeting 2007, Symposium I, by Eugen M. Sheregii
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-15 13:57
Revised:   2009-06-07 00:44