Journal of Inorganic Materials

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Temperature-dependent Raman Property of Al-doped 6H-SiC Crystals

LI Xiang-Biao1, 2, SHI Er-Wei1, CHEN Zhi-Zhan1, XIAO Bing1   

  1. 1. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China; 2. Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
  • Received:2007-03-29 Revised:2007-05-12 Published:2008-03-20 Online:2008-03-20

Abstract: Al-doped and un-doped 6H-SiC crystals were grown by physical vapor transport (PVT) method. Raman spectra were measured from room temperature to 400℃. The Raman requencies were shifted to lower wavenumber and Raman peaks were broadened with increasing temperature for both samples due to thermal expansion and optical phonons decay. Free carrier concentration in Al-doped sample was increased with increasing temperature due to increasing of the plasma concentration, which correspondingly enhanced more strong coupling interactions among LO phonons, plasma, and free carriers. Therefore, the intensity of A1 (LO) mode for Al-doped sample decreased obviously and maintained unchangeable for un-doped sample. The Al activation behavior and its contribution to free carriers in high temperatures were analyzed theoretically and demonstrated experimentally.

Key words: SiC crystals, high temperature Raman spectra, doping, free carrier

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