Electronic properties of doped SiC at elevated temperatures studied by Raman scattering

被引:10
作者
Harima, H [1 ]
Hosoda, T [1 ]
Nakashima, S [1 ]
机构
[1] Osaka Univ, Dept Appl Phys, Suita, Osaka 565, Japan
来源
SILICON CARBIDE, III-NITRIDES AND RELATED MATERIALS, PTS 1 AND 2 | 1998年 / 264-2卷
关键词
Raman scattering; LO phonon; plasmon; coupled mode; damping; fano interference; high temperature; carrier density; mobility;
D O I
10.4028/www.scientific.net/MSF.264-268.449
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Raman spectra from n-type 4H-SiC crystals with different carrier concentrations have been measured in a temperature range from 10K up to 1500K. Characteristic temperature variation has been observed for the spectra of LO-phonon-plasmon coupled modes in heavily-doped samples: when the temperature is raised, e.g., the peak frequency and width increase until 400-500K, and then decrease monotonously. Such behavior is in contrast to the one in lightly-doped samples where only monotonous changes are observed. A lineshape-fitting analysis shows that large damping rates of free carriers, which further increase with the rise of temperature steeply, play critical roles in the formation of coupled-mode profiles. Distortion of lineshape in low-frequency phonon bands, which is due to Fano interference, has also been measured in detail. The distortion is weakened at higher temperatures, indicating that relative intensity of Raman matrix element of phonon excitation to that of single-particle excitation of free carriers increases with the rise of temperature.
引用
收藏
页码:449 / 454
页数:6
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