Document Type

Article

Publication Date

2-2011

Abstract

We report the first experimental evidence for the direct excitation of coherent high-frequency acoustic phonons in semiconducting doping superstructures by electromagnetic fields of the same frequency. Nanosecond pulses of acoustic phonons have been detected by a superconducting bolometer at the appropriate time-of-flight across a (100) silicon substrate for ballistic longitudinal phonons when a silicon doping superlattice is illuminated with grating-coupled nanosecond-pulsed 246-GHz laser radiation with power density of ∼1 kW/mm2. The absorbed phonon power density in the microbolometer is estimated to be ∼ 10/Wmm2, in agreement with theory. The phonon pulse duration matches the laser pulse duration. The absence of any detected transverse acoustic phonon signal by the superconducting bolometer is particularly striking. We believe these observations provide the first evidence that coherent zone-folded longitudinal acoustic phonons can be generated in a silicon doping superlattice and with negligible associated heat pulse generation, through the resonant absorption of grating-coupled pulsed far-infrared laser radiation.

Comments

This paper was presented by Thomas E. Wilson at PHONONS 2010 – 13th International Conference on Phonon Scattering in Condensed Matter in Taipei, Taiwan, April, 2010, paper MA2.

Published in the Chinese Journal of Physics, the journal of The Physical Society of the Republic of China, available at http://PSROC.phys.ntu.edu.tw/cjp. Reprinted with permission.

© 2011 THE PHYSICAL SOCIETY OF THE REPUBLIC OF CHINA. All rights reserved

Download

Share

COinS