세종대학교 물리학과
세종대학교 물리학과
학과소개 학과소개 새소식 학사정보 연구실/사람들 동문마당 게시판/자료실


2016.12.07
[콜로퀴움] High field THz spectroscopy of graphene

‧제목  High field THz spectroscopy of graphene:
the effect of doping and grain size on the carrier relaxation
‧연사  임성주 교수 (성균관대학교)
‧일시  2016년 12월 7일 (수요일) 오후 5시
‧장소  영실관 613호

초 록

The presentation addresses the effect of carrier concentration and grain size on optical conductivity of graphene monolayer, respectively. The optical conductivity of graphene is measured using high field THz  ranging up to ETHz=282 kV/cm.
The carrier concentration n is modulated using a backgate bias, whereas the grain size is controlled through the growth parameters. The electrons in the graphene are accelerated by THz field, gain kinetic energy, and relax their energy through the interaction to the grain boundaries and optical phonons. Depending on the carrier concentration, the optical conductivity of graphene changes from semiconductor-like (at low n) to metal-like (at high n) behavior. In particular, at low carrier concentration, the relaxation of energetic carriers is significantly suppressed.
When the grain size of the graphene changes, the carrier temperature in the graphene varies, which is attributed to the supercollision of low energy carriers to defects. The understanding on the dynamics of carriers under intense THz field can give an insight to the application of graphene for high speed electronics.





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