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Analysis of Far Infrared Spectra Showing Bulk and Surface Phonon‐Polaritons in CdTe Epilayers on GaAs Substrates
Author(s) -
Dumelow T.,
El Gohary A. R.,
Maslin K. A.,
Parker T. J.,
Tilley D. R.,
Ershov S. N.
Publication year - 1990
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221610123
Subject(s) - cadmium telluride photovoltaics , materials science , epitaxy , substrate (aquarium) , polariton , layer (electronics) , optoelectronics , semiconductor , spectroscopy , spectral line , attenuated total reflection , metalorganic vapour phase epitaxy , infrared spectroscopy , optics , infrared , analytical chemistry (journal) , chemistry , physics , nanotechnology , oceanography , quantum mechanics , astronomy , chromatography , geology , organic chemistry
A theoretical interpretation is given of far infrared measurements by dispersive Fourier transform spectroscopy (DFTS) and attenuated total reflection (ATR) spectroscopy on two semiconductor samples, each consisting of a CdTe epitaxial layer deposited by plasma MOCVD on a GaAs substrate. In each case calculation gives a very good description of the measured spectra. The DFTS measurements reveal both the CdTe and GaAs reststrahlen bands, which lie in well‐separated spectral ranges. At frequencies above the CdTe reststrahlen band, where the CdTe layer behaves effectively as a dielectric film, interference between the beams reflected from the top and bottom of the layer leads to striking structure in the phase spectrum. ATR measurements are made in both p and s polarisation, and it is shown that a p‐polarised surface polariton is detected in the CdTe reststrahlen band, and both p‐ and s‐polarised guided waves are detected in the GaAs reststrahlen band. The frequency of the s‐polarised guided mode is found to vary with layer thickness, and both techniques provide a sensitive probe of the layer thickness.