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SiGe layer thickness effect on the structural and optical properties of well-organized SiGe/SiO2 multilayers
E M F Vieira1, J Toudert2, A G Rolo3
1University of Minho, CMEMS-UMINHO, Campus Azurem, 4804-533 Guimaraes, Portugal.
Nanotechnology
|June 20, 2017
Summary
We produced silicon-germanium/silicon dioxide (SiGe/SiO2) multilayers with SiGe nanocrystals. Annealing at 1000°C formed stable SiGe nanocrystals, showing blue-shifted optical absorption and electronic confinement.
Area of Science:
- Materials Science
- Nanotechnology
- Semiconductor Physics
Background:
- Multilayer structures are crucial for advanced electronic and optoelectronic devices.
- Silicon-germanium (SiGe) alloys offer tunable electronic properties.
- Controlling nanocrystal formation in multilayers is key for novel applications.
Purpose of the Study:
- To produce regular (SiGe/SiO2)20 multilayer structures.
- To investigate the structural and optical properties of SiGe nanocrystals within SiO2 matrix.
- To understand the effect of SiGe layer thickness on nanocrystal formation and properties.
Main Methods:
- Radio frequency (RF)-magnetron sputtering for multilayer fabrication.
- Transmission electron microscopy (TEM) and scanning TEM (STEM) for structural analysis.
- Raman spectroscopy, X-ray reflectometry, and spectroscopic ellipsometry for material characterization.
- Low-temperature photoluminescence (PL) for optical emission studies.
Main Results:
- Stable (SiGe/SiO2)20 multilayers were produced via sputtering at 350°C and annealed at 1000°C.
- Reducing SiGe layer thickness led to a transition from continuous layers to isolated SiGe nanocrystals (3-8 nm).
- Spectroscopic ellipsometry revealed a blue-shift in optical absorption for thinner SiGe layers, indicating quantum confinement.
Conclusions:
- Annealing promotes the formation of stable SiGe nanocrystals within SiO2 layers.
- SiGe layer thickness critically influences the transition to nanocrystalline structures.
- Observed optical properties suggest electronic confinement effects in the SiGe nanocrystals.
