Yang Yin-Tang(杨银堂)a)†, Han Ru(韩茹)a), and Wang-Ping(王平)b)
a School of Microelectronics, Xidian University, Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, Xi'an 710071, China; b Qimonda Technologies Xi'an, Xi'an 710075, China
Abstract This paper employs micro-Raman technique for detailed analysis of the defects (both inside and outside) in bulk 4H-SiC. The main peaks of the first-order Raman spectrum obtained in the centre of defect agree well with those of perfect bulk 4H-SiC, which indicate that there is no parasitic polytype in the round pit and the hexagonal defect. Four electronic Raman scattering peaks from nitrogen defect levels are observed in the round pit (395 cm$^{-1}$, 526 cm$^{-1}$, 572 cm$^{-1}$, and 635 cm$^{-1})$, but cannot be found in the spectra of hexagonal defect. The theoretical analysis of the longitudinal optical plasmon--phonon coupled mode line shape indicates the nonuniformity of nitrogen distribution between the hexagonal defect and the outer area in 4H-SiC. The second-order Raman features of the defects in bulk 4H-SiC are well-defined using the selection rules for second-order scattering in wurtzite structure and compared with that in the free defect zone.
Received: 01 December 2007
Revised: 17 April 2008
Accepted manuscript online:
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