We present an ellipsometric study of Zn1-xCoxSe films with 0≤x<0.1 grown on GaAs substrates. We attribute the significant distortions of the interference patterns at energies between 1.6 and 1.8 eV to absorption due to localized d-state transitions between the crystal-field levels of Co2+ ions on Zn sites. There is also evidence of an absorption feature near 4.3 eV within the E0+Δ0-E1 band-gap region. We propose that this structure has the characteristics of a charge-transfer-type p-to-d transition. A similar absorption band also seems to be present in Zn1-xFexSe system.
ASJC Scopus subject areas
- Condensed Matter Physics