Evaluation of the bond polarizabilities of zincblende‐type semiconductors: Application to the Raman spectra of disordered GaSb/AlSb (001) superlattices

We derive expressions for the bond polarizability (BP) parameters involving only directly measurable quantities, such as dielectric and elasto-optic constants of the bulk crystal and apply them to zincblende-type crystals. The vibrational modes are calculated on the basis of an eleven (11) parameter rigid-ion model approximation (RIM). Having estimated the BP parameters for GaSb and AlSb bulk crystals, we calculate the Raman spectra away of resonance conditions for the vibrations of perfect and disordered (GaSb)1/(AlSb)1 (001) superlattices (SL). The disordered SL is approximated with primitive cells much larger than the primitive cell of the perfect 1?x?1?SL. Furthermore, we show that disorder modifies the Raman spectra of the perfect SL by introducing asymmetry as well as by the formation of additional peaks in both the acoustic and optical range of the Raman spectra. Puzzlingly, even a small degree of disorder, results in a blueshift of all modes frequencies, especially the strongest optical ones.