Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 24: Poster Session: Ge/Si/SiC / III - V Semiconductors
HL 24.14: Poster
Montag, 26. März 2012, 16:00–19:00, Poster D
Coherent phonon excitation in SiC — Toru Shimada1, •Wiktor Pronobis1, Martin Scheuch1, Kamaraju Natarajan1, Christian Frischkorn2, Martin Wolf1, and Tobias Kampfrath1 — 1Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin — 2Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin
Silicon carbide (SiC) is a prominent material for high-temperature, high-power, high-frequency and radiation-resistant devices. In view of these important applications, it is of great interest to characterize the basic solid-state properties of this material. Here, we consider coherent vibrations of the crystal lattice (coherent phonons) which we trigger by impulsive excitation with a femtosecond laser pulse (pump pulse). A second time-delayed laser pulse (probe pulse) is used to monitor the lattice vibration in the time domain by measuring the pump-induced birefringence of the sample as a function of the delay between pump and probe pulses. Based on the temperature dependence of their decay, we discuss the anharmonic coupling of the LO (29.3 THz) and the folded TO (23.8 THz) phonon mode in the 3C (cubic) and 6H (hexagonal) polytypes of SiC, respectively.