Abstract
We have used spectroscopic ellipsometry to determine the complex dielectric function of a series of ternary Be x Zn 1− x Te thin films grown by molecular beam epitaxy. The II–VI semiconductor alloys were grown on InP substrates that had an InGaAs buffer layer. After the growth, X-ray diffraction experiments were performed in order to determine the alloy concentration. A standard inversion technique was used to obtain the dielectric functions from the measured ellipsometric spectra, obtained between 2000 nm (5000 cm −1) and 40,000 nm (250 cm −1). By modelling the dielectric function as a collection of oscillators, representing longitudinal and transverse optical phonons of the Be x Zn 1− x Te lattice, we were able to recover the phonon spectra for this alloy system. It is argued that the additional phonon modes that are obtained from ellipsometry are best understood from the recently-proposed percolation model.
Published Version
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