Phonon coupling in GaAs/AlxGa1-xAs observed by picosecond Raman scattering
The authors measure the hot phonon population of the GaAs LO phonons using a picosecond Raman scattering technique. Their samples were a series of GaAs/Al0.4Ga0.6As superlattices (SLS) with a fixed well width (Lz) and varying barrier width (Lb). An abrupt increase in the phonon generation rate was observed as Lb decreased over a narrow range. This is interpreted as the onset of significant well-to-well coupling of the confined GaAs LO phonons. An estimate of the LO phonon penetration depth into the Al0.4Ga0.6As barriers is obtained from this transition.