Coherent Subterahertz Phonons in InAs/GaSb Superlattices

The generation and propagation of coherent phonons in short-period InAs/GaSb superlattices grown on GaSb(001) substrates are investigated using laser photoacoustic techniques. It is shown that the excitation of a (110)-oriented cleaved edge of the heterostructure by femtosecond laser pulses leads to the generation of coherent subterahertz phonons that propagate at a small angle with respect to the (110) surface and interact efficiently with electromagnetic radiation polarized perpendicularly to the superlattice layers. The revealed features of the interaction between electromagnetic radiation and folded acoustic modes have allowed us to propose a new method for the local analysis of the crystal structure of InAs/GaSb superlattices with an accuracy comparable to that of X-ray techniques.