ABSTRACT
The optical confined modes of the (31l)-oriented GaAs/AlAs superlattices were investigated by Infrared Fourier Transform Spectroscopy. The analysis of confined TO and LO vibrational modes observed in experimental IR reflection spectra shows no marked difference between superlattices grown on (311)A and (311)B surfaces. Moreover, no evidence of optical anisotropy caused by corrugation of the (311)A surface was obtained. The comparison of the frequencies of TO confined modes in short-period (311) superlattices with the dispersion of GaAs phonons obtained for long-period superlattices allows to conclude that even confined modes usually forbidden in infrared are active in the case of the (311) short-period superlattices due to different arrangement of normal (AlAs on GaAs) and inverted (GaAs on AlAs) interfaces.
