Abstract
Coherent phonon spectroscopy of an a -plane wurtzite InN epitaxial thin film is demonstrated with time-resolved second-harmonic generation technique. Coherent E1 (LO) phonons are launched via a transient electric field screening process in the near surface region of the a -plane wurtzite InN. Because of the macroscopic electric dipole interaction between coherent E1 (LO) phonons and photoexcited plasmons, two hybridized vibration modes, phononlike (L-) and plasmonlike (L+) E1 (LO) phonon-plasmon coupling modes, are identified. The investigation of these coupling modes allows us to understand the ultrafast carrier and phonon dynamics in a -plane wurtzite InN. © 2008 American Institute of Physics.