Folded acoustic phonons in InAs-AlAs strained-layer superlattices
Raman spectroscopy is used to characterize highly mismatched (7%) InAs‐AlAs superlattices grown by atomic layer molecular beam epitaxy. In particular, folded acoustic modes are presented and compared with two different theoretical models (Rytov and linear chain). We find good agreement between theory and experiments. We estimate, with a simple model, the magnitude of the effect of the strain on the phonon frequency shifts.
Dependence of Raman frequencies and scattering intensities on pressure in GaSb, InAs, and InSb semiconductors
The first-order Raman scattering by TO and LO phonons has been measured in GaSb, InAs, and InSb under hydrostatic pressures up to their phase transitions. The Raman frequencies increase nearly linearly while the LO-TO splitting decreases with increasing pressure. The scattering intensities display strong enhancement as the ${E}_{1}$ band gaps approach the laser frequencies with increasing pressure. The measured volume dependence of the Raman frequencies and the transverse effective charges is interpreted by means of pseudopotential calculations. The resonance behavior is discussed in terms of resonant Raman scattering near the ${E}_{1}$ gaps.
Acoustic phonon transmission in superlattices
The transmission of acoustic phonons through single and multiple layers of AlxGa1-xAs in GaAs is calculated with full account taken of the elastic discontinuities and anisotropies. The results bear on the interpretation of thermal and transport experiments on superlattices, and indeed suggest new experiments.