ABSTRACT
This chapter discusses the relevant electronic, photonic, and phononic properties of semiconductor superlattices (SL). It describes the experimental arrangements for the generation and detection of monochromatic phonons. The chapter explores longitudinal polarized and transverse polarized phonons and explains the measurement of the mean free path of terahertz phonons in Gallium Arsenide (GaAs). It considers some preliminary measurements on aluminum nitride/Gallium nitride (AlN/GaN) systems, which offer the possibility of a much more intense source of monochromatic phonons. The chapter deals with a discussion of outstanding problems and future applications of the techniques. It also considers SLs based on the III–IV semiconductors AlAs and GaAs. Coherent phonon oscillations in AlAs/GaAs SLs were observed to decay on a time scale of approximately 100 ps, and it was suggested that this was due to dephasing. The phonon signal is largely due to energy relaxation by photoexcited carriers in the GaAs substrate.
