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Phonon Dispersion이 열전달 모델에 미치는 영향
정재동(Jae Dong Chung) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
The effect of (1) phonon dispersion in thermal conductivity model and (2) the differentiation of<br/> group velocity and phase velocity for Ge is examined. The results show drastic change of thermal<br/> conductivity regardless of using same relaxation time model. Also the contribution of transverse acoustic<br/> (TA) phonon and longitudinal acoustic (LA) phonon is changed by considering more rigorous dispersion<br/> model. Holland model underestimates the scattering rate for high frequency TA, so misleading<br/> conclusion, i.e. TA is dominant heat transfer mode at high temperature. But the actual reduction of<br/> thermal conductivity is much larger than the estimation by Holland model and high frequency TA is<br/> no more dominant heat transfer mode. Another heat transfer mechanism may exist for high temperature.<br/> Two possible explanations are (1) high frequency LA by Umklapp scattering and (2) optical phonon.