Publication Type Journal Article
Title Point defects in BaSi2 thin films for photovoltaic applications studied by positron annihilation spectroscopy
Authors A. Montes S. W. H. Eijt Y. Tian R. Gram H. Schut T. Suemasu N. Usami M. Zeman Joao Serra O. Isabella
Groups MTFT
Journal JOURNAL OF APPLIED PHYSICS
Year 2020
Month February
Volume 127
Number 8
Pages
Abstract Barium di-silicide (BaSi2) is a very promising absorber material for high-efficiency thin-film solar cells, due to its suitable bandgap, high light absorption coefficient, and long minority-carrier lifetime. In this study, we compare the nanostructure, layer composition, and point defects of BaSi2 thin films deposited by Radio Frequency (RF) sputtering, Thermal Evaporation (TE), and Molecular Beam Epitaxy (MBE), using Doppler Broadening Positron Annihilation Spectroscopy (DB-PAS) depth profiling, Raman spectroscopy, and x-ray diffraction. Our DB-PAS study on thermally annealed RF-sputter deposited and on TE-deposited BaSi2 layers, in a comparison with high quality BaSi2 films produced by MBE, points to the presence of vacancy-oxygen complexes and Si or Ba mono-vacancies, respectively, in the (poly)crystalline BaSi2 films. The degree of near-surface oxidation increases, going from MBE and TE to the industrially applicable RF-sputtered deposition synthesis. The use of a-Si capping layers on the thermally annealed RF-sputtered BaSi2 films leads to a clear reduction in sub-surface oxidation and improves the quality of the BaSi2 films, as judged from DB-PAS. Published under license by AIP Publishing.
DOI http://dx.doi.org/10.1063/1.5126264
ISBN
Publisher AMER INST PHYSICS
Book Title
ISSN 0021-8979
EISSN 1089-7550
Conference Name
Bibtex ID ISI:000524947700003
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