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The Influence of Surface Layers on Photoreflectance in the Exciton Region of CdS
Author(s) -
Risch L.
Publication year - 1978
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.2220880112
Subject(s) - exciton , electric field , coulomb , crystal (programming language) , spectral line , electron , reflectivity , surface (topology) , free electron model , materials science , condensed matter physics , molecular physics , chemistry , optics , physics , quantum mechanics , astronomy , computer science , programming language , geometry , mathematics
Changes of exciton reflectance spectra by an intense light beam (photoreflectance) are used to investigate electric fields on the free, unprepared crystal surface, originating from surface states. There are two types of photoreflectance spectra in CdS at 105 K, which are associated to different crystal properties A and B. The electric field increases in type A crystals and decreases in the case of type B crystals. This mechanism produces the main contribution to photoreflectance; the screening of the Coulomb interaction of the excitons by free electrons is negligible.