Synthesis and characterization of silicon clathrates of type I Na8Si46 and type II NaxSi136 by thermal decomposition
Fix T. 1Chevalier C. 2Rehspringer J.-L. 3Vollondat R. 4Roques S. 5Bartringer J. 1Slaoui A.1
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作者信息
1. Laboratoire des Sciences de l'Ingénieur de l'Informatique et de l'Imagerie (ICube) CNRS and University of Strasbourg
2. Université de Lyon
3. Institut des Nanotechnologies de Lyon INL-UMR5270 CNRS
4. INSA Lyon
5. Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) UMR7504 CNRS and University of Strasbourg
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Abstract
? 2022 Elsevier B.V.Type I (Na8Si46) or type II (Nax≤24Si136) silicon clathrates films with a large 15 × 45 mm2 surface have been synthesized from p-type and intrinsic c-Si (001) wafers using a two-step process without the need of any glove box. Conditions to selectively obtain either type I or type II silicon clathrates phase have been finely tuned. Optical absorption coefficients are found much larger in the Si clathrates than in diamond silicon in the visible light range. Type II films provide a direct bandgap of around 1.9 eV which is supporting the high absorption coefficient observed. Photovoltaic response of the films has been confirmed using Surface Photovoltage. As prepared type II films show many surface defects, cracks and inhomogeneities which have been drastically reduced thanks to a pressure annealing treatment.
NSTL
Elsevier