We have investigated the resonance enhancement of the Raman scattering efficiency of the TO, LO, and 2LO phonon processes in a series of HgTe/${\mathrm{Hg}}_{0.3}$${\mathrm{Cd}}_{0.7}$Te heterostructures with (001), (110), and (111) orientations at the ${\mathit{E}}_1$ band gap. In addition, interface modes and localized defect modes have been observed. Quantum confinement effects could be detected at the ${\mathit{E}}_1$ transition in this system and a second (excited) electronic subband was verified. For the (110) and (111) orientations, the electronic degeneracy at the ${\mathit{E}}_1$ gap is lifted and two resonance maxima appear, in accordance with the transverse effective mass (0.145${\mathit{m}}_0$) derived for a (001) grown sample. Selection rules for Raman backscattering from zinc-blende heterostructures in the vicinity of the ${\mathit{E}}_1$ gap have been derived for deformation-potential and Fröhlich intraband coupling and are compared with experimental results. © 1996 The American Physical Society.

• Received 9 April 1996

DOI:https://doi.org/10.1103/PhysRevB.54.16907