ISSN:
1057-9257
Keywords:
Heteroepitaxy
;
CdS
;
Crystal structure
;
Photoluminescence
;
Reflection
;
Thin films
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
Notes:
CdS films were prepared by molecular beam epitaxial growth on clean cleaved InP(110) substrates. Films with thicknesses in the 200 nm range were studied by optical techniques: spectroscopic ellipsometry, reflection and photoluminescence. The film thickness and the dielectric function of the films are evaluated from the ellipsometry data. The feature in the imaginary part of the film dielectric function which is induced by the E1 interband transition in CdS is found to be extremely sensitive to the crystal modification. A splitting of this feature occurring at approximately 200 nm indicates a phase transition in the thin films from the cubic to the hexagonal modification. This is confirmed by reflection measurements which show two series of reflection loops for both modifications for film thickness exceeding 200 nm. The energy positions of the free excitons of the hexagonal and cubic modifications are derived. In addition, the band gap for the cubic modification is determined for the first time. The photoluminescence spectra also reveal cubic and hexagonal contribution of donor-acceptor pair recombinations. From the excitonic transitions attempts are made to identify the main impurities in the layers.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/amo.860030104
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