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HL: Fachverband Halbleiterphysik
HL 71: Quantum Dots and Wires: Optical Properties
HL 71.12: Talk
Thursday, March 10, 2016, 12:45–13:00, H15
Characterization of nanocrystalline Si/SiC layers through optical measurements and simulations — •Johannes Hofmann, Charlotte Weiss, and Stefan Janz — Fraunhofer Institute for Solar Energy Systems, Heidenhofstraße 2, 79110 Freiburg, Germany
Silicon (Si) nanocrystal materials are subject to intense research concerning their application in Si-based tandem solar cells, since exploiting finite size effects in the Si nanostructures allows for modifying band structure properties and thus tailoring absorption characteristics.
Annealing of sub-micrometer amorphous-SixC1-x:H layers (x>0.5) deposited by plasma-enhanced chemical vapor deposition yields layers comprising a silicon carbide (SiC) matrix and therein embedded Si nanoclusters with a characteristic size of a few nanometers. For this work we investigate the optical properties of such layers by spectral ellipsometry, spectrophotometry measurements as well as photoluminescence measurements; structural characterization (X-ray diffraction, Fourier transform infrared spectroscopy) is also performed. Thickness variation sample series are analyzed by means of model based spectrum simulation and subsequent regression analysis. Scanning electron microscopy cross section images serve as references for thickness determination. Consequently, an optical thickness measuring method for annealed layers depending on their composition is provided. It is furthermore aimed at detecting the contribution of finite size effects in Si nanocrystals to the optical properties of the layers.