Femtosecond optical excitation of coherent acoustic phonons in a piezoelectric p-n junction
Journal
Physical Review B - Condensed Matter and Materials Physics
Journal Volume
84
Journal Issue
20
Date Issued
2011
Author(s)
Abstract
We present a theoretical model for the photogeneration of coherent acoustic phonons in a piezoelectric p-n junction. In our model, the transport of photoexcited carriers is governed by the drift-diffusion equation, whereas the dynamics of acoustic phonons obeys a loaded string equation. Among various mechanisms, the piezoelectric coupling is found to dominate the acoustic-phonon generation process. The waveform of the photogenerated acoustic pulse is strongly influenced by the various dynamics of the photoexcited carriers, especially the picosecond hole drifting. Our calculation also confirms the crucial role of the built-in electric field in the formation of coherent acoustic phonons under optical excitations.
Type
journal article