Miniband Effects in Short‐period InGaAs/InP Superlattices

The formation of the miniband electron energy structure and its effect on optical vibrational modes were explored in doped InGaAs/InP superlattices with different periods. The analysis of the high resolution x‐ray diffraction and Raman data allowed us to conclude that in spite of the defect structure of the layers constituting the superlattices, their super‐periodicity was well defined. The quantitative proof of the conditions for break‐down of the Raman selection rules is presented. No Raman selection rules were observed for the longitudinal optical phonons in long‐period superlattices. In short‐period superlattices the emergence of the selection rules of the coupled plasmon‐LO phonon vibrations was demonstrated to occur due to the increase of their coherence lengths.