Local atomic structure and lattice defect analysis in heavily Co-doped ZnS thin films using X-ray absorption fine structure spectroscopy
- CINVESTAV Unidad Mérida, Yucatán (Mexico)
- Stanford Univ., CA (United States)
- Univ. Marista de Mérida, Yucatán (Mexico)
Iin this work, X-ray absorption fine structure (XAFS) spectroscopy was used to address both the local atomic structure and the local electronic structure around Zn, Co, and S in Co-doped ZnS thin films. X-ray absorption near-edge spectroscopy (XANES) revealed changes in the strong pre-edge feature of the S K-edge spectra that depend on the Co concentration and are related to atomic bound-state transitions through hybridization between $3d$ transition metal and $sp$ host semiconductor electronic states. These changes reveal intrinsic effects, such as S vacancies and dopant effects. From the Co K-edge XANES spectra, substitution of Co2+ into ZnS is observed. The local atomic structure around the dopant, obtained by XAFS spectroscopy, indicates a reduction of the Co–S bond length. Optical analysis shows deep absorption centers or intermediate states in the bandgap, ascribed to $$d$$-$$d$$ transitions in the Co atoms that modify the electronic band structure and cause a decrease in the bandgap as a function of Co concentration. This work provides direct evidence of dopant effects in heavily Co-doped ZnS, including bond distances and Debye-Waller factors, providing key elements to generate a realistic atomic structural model, which is crucial to understand the observed electronic properties of this material.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); Secretaría de Educación Pública-Consejo Nacional de Ciencia y Tecnología (SEP-CONACYT); LANNBIO, CINVESTAV, Mexico
- Grant/Contract Number:
- 169108; 2008-108160; 123913; AC02-76SF00515
- OSTI ID:
- 1604748
- Alternate ID(s):
- OSTI ID: 1703239
- Journal Information:
- Journal of Physics and Chemistry of Solids, Vol. 136, Issue C; ISSN 0022-3697
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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