Band-edge modification and mid-infrared absorption of co-deposited FexZn1-xS thin films

Autor: Zahra Ghadyani, Eric Karhu, Morten Kildemo, Turid Worren Reenaas, Nelly-Ann Molland, Stefano Poggio, Mohammadreza Nematollahi, Joseph J. BelBruno, Ursula J. Gibson
Jazyk: angličtina
Rok vydání: 2015
Předmět:
Zdroj: Optical materials express, 5(7), 1613-1620. The Optical Society
Optical Materials Express
ISSN: 2159-3930
Popis: The bandgap of iron-doped ZnS has been reported by others to change significantly under the addition of a few atomic percent of iron, which would have significant implications for solar energy. Here, thin films of FexZn1-xS with x = 0 to 0.24 were made by co-deposition of Fe and ZnS using thermal evaporation. In contrast to results on nanoparticles and electrodeposited materials, all co-deposited films had optical properties consistent with a direct bandgap of ~3-3.5 eV. The absorption peak at 2.7 µm from substitutional Fe2+ in the ZnS films was well isolated up to concentrations of over 2% (~1021cm−3), despite the small crystallite size, suggesting the films may have applications as mid-infrared saturable absorbers. Increasing dopant concentration resulted in band edge softening. Density functional calculations are presented and are consistent with our observations of the Fe:ZnS films, demonstrating spin-polarized midgap states and additional states at the band edge. © 2015 Optical Society of America. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.
Databáze: OpenAIRE