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Raman and Infrared Spectroscopy of Optical Phonons in II–VI Alloys, Epilayers and Superlattices
Author(s) -
Vogelgesang R.,
Mayur A. J.,
Dean Sciacca M.,
Oh Eunsoon,
Miotkowski I.,
Ramdas A. K.,
Rodriguez S.,
Bauer G.
Publication year - 1996
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199603)27:3/4<239::aid-jrs968>3.0.co;2-7
Subject(s) - raman spectroscopy , phonon , superlattice , raman scattering , molecular beam epitaxy , condensed matter physics , ternary operation , molecular vibration , infrared , materials science , spectroscopy , chemistry , optics , epitaxy , physics , nanotechnology , layer (electronics) , quantum mechanics , computer science , programming language
The multimode behavior of the zone center optical phonons in bulk crystals and molecular beam epitaxy (MBE) grown epilayers of the tetrahedrally coordinated II–VI semiconductor alloys was investigated using Raman and infrared spectroscopy. Depending on the inter‐atomic force constants and the relative nuclear masses of the constituents, the zone center optical modes of the ternary A 1‐x B x C exhibit either a two‐mode behavior with distinct AC‐like and BC‐like TO and LO modes across the entire composition range, or an intermediate mode behavior when the masses of A and B are more closely matched. When B is much lighter than A, the BC‐like TO and LO modes emerge from the localized vibrational mode of B in AC when x≈ 0 and the AC‐like TO and LO modes converge into the gap mode of A in BC as x→ 1. A quaternary A 1‐x‐y B x C y D may similarly exhibit a distinct three‐mode or intermediate‐mode behavior depending on the relative masses of the constituents. The two‐mode behavior in bulk Zn 1‐x Mg x Te and the three‐mode behavior in bulk Cd 1‐x‐y Zn x Mg y Te were studied with Raman scattering. Using infrared transmission at oblique incidence, i.e. the Berreman technique, the zone center TO and LO modes of MBE‐grown zinc blende MnTe are observed as transmission minima. The observation of confined optical phonons in ultra‐thin CdTe/ZnTe superlattices by exploiting the Berreman technique and Raman scattering permits their bulk dispersions to be delineated.