Structural and optical properties of size controlled Si nanocrystals in Si{sub 3}N{sub 4} matrix: The nature of photoluminescence peak shift
- Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)
- Department of Electronic and Electrical Engineering, Trinity College Dublin, Dublin 2 (Ireland)
- Institute for Applied Materials (IAM) and Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
- MATIS IMM-CNR, Universita' di Catania, Via S. Sofia 64, I-95123 Catania (Italy)
- Fraunhofer-Institut für Solare Energiesysteme ISE Heidenhofstr. 2, 79110 Freiburg (Germany)
- MIND-IN2UB, Departament d’Electrònica, Universitat de Barcelona, C/Martí i Franquès, 1, 08028 Barcelona (Spain)
Superlattices of Si{sub 3}N{sub 4} and Si-rich silicon nitride thin layers with varying thickness were prepared by plasma enhanced chemical vapor deposition. After high temperature annealing, Si nanocrystals were formed in the former Si-rich nitride layers. The control of the Si quantum dots size via the SiN{sub x} layer thickness was confirmed by transmission electron microscopy. The size of the nanocrystals was well in agreement with the former thickness of the respective Si-rich silicon nitride layers. In addition X-ray diffraction evidenced that the Si quantum dots are crystalline whereas the Si{sub 3}N{sub 4} matrix remains amorphous even after annealing at 1200 °C. Despite the proven Si nanocrystals formation with controlled sizes, the photoluminescence was 2 orders of magnitude weaker than for Si nanocrystals in SiO{sub 2} matrix. Also, a systematic peak shift was not found. The SiN{sub x}/Si{sub 3}N{sub 4} superlattices showed photoluminescence peak positions in the range of 540–660 nm (2.3–1.9 eV), thus quite similar to the bulk Si{sub 3}N{sub 4} film having peak position at 577 nm (2.15 eV). These rather weak shifts and scattering around the position observed for stoichiometric Si{sub 3}N{sub 4} are not in agreement with quantum confinement theory. Therefore theoretical calculations coupled with the experimental results of different barrier thicknesses were performed. As a result the commonly observed photoluminescence red shift, which was previously often attributed to quantum-confinement effect for silicon nanocrystals, was well described by the interference effect of Si{sub 3}N{sub 4} surrounding matrix luminescence.
- OSTI ID:
- 22259294
- Journal Information:
- Journal of Applied Physics, Vol. 114, Issue 18; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
77 NANOSCIENCE AND NANOTECHNOLOGY
ANNEALING
CHEMICAL VAPOR DEPOSITION
DIFFUSION BARRIERS
LAYERS
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
PLASMA
QUANTUM DOTS
RED SHIFT
SILICA
SILICON
SILICON NITRIDES
SILICON OXIDES
SUPERLATTICES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
VENTILATION BARRIERS
X-RAY DIFFRACTION