title: Coherent acoustic phonon oscillations in semiconductor multiple quantum wells with piezoelectric fields
abstract: Large coherent acoustic phonon oscillations were demonstrated using InGaN/GaN multiple quantum wells with piezoelectric fields. With UV femtosecond pulse excitation, photogenerated carriers screened the piezoelectric field and initiated the displacive coherent phonon oscillations. The specific phonon frequency was selected by the coupling between the periodic carrier distribution and the corresponding acoustic phonon mode. The induced acoustic phonon oscillation resulted in piezoelectric field modulation and then caused absorption variation through the quantum confined Franz-Keldysh effect. The wave vector uncertainty due to the finite sample width was found to determine the observed dephasing time.
authors.affiliation: Department of Electrical Engineering and Graduate Institute of Electro-Optical Engineering, Taipei 10617, Taiwan, Republic of China.
authors.initials: CK
authors.lastname: Sun
authors.initials: JC
authors.lastname: Liang
authors.initials: XY
authors.lastname: Yu