DETERMINATION OF BETE PHONON-DISPERSION BY RAMAN-SPECTROSCOPY ON BETEZNSE-SUPERLATTICES/

We present an investigation of the vibrational properties and the elas tic constant c(11) of BeTe. For this purpose we applied Raman spectros copy on folded acoustic phonons (FAPs) and confined optical phonon mod es in BeTP/ZnSe superlattices. This method yields basic BeTe vibration al properties as well as the inter-face properties at the BeTe/ZnSe ju nctions. The exact values of the superlattice periodicity were obtaine d from X-ray diffraction, while transmission electron microscopy data supplied the individual thicknesses of the ZnSe and BeTe layers. The a coustic phonon dispersion in BeTe was determined from the FAP frequenc ies in the Raman spectra, together with the periodicity and the thickn ess ratio of the SL as well as the well known elastic constants of the ZnSe layers. We obtained for the BeTe sound velocity the value of 418 0 +/- 200 m/s. This value was used to calculate the BeTe elastic const ant c(11), yielding 8.9 +/- 0.9 X 10(10) N/m(2). (C) 1998 Elsevier Sci ence B.V.