Sponge-like Si-SiO2 nanocomposite for PV applications


Sponge-like Si-SiO2 nanocomposite for PV applications

Liedke, B.; Heinig, K.-H.; Friedrich, D.; Schmidt, B.; Mücklich, A.; Keles, U.; Bulutay, C.

The aim of this talk is to explain method of fabrication, modification and optimization of Sponge-like Si-SiO2 nanocomposite.
It consists of Si embedded in SiO2 fabricated by spinodal decomposition of sputter-deposited silicon-rich oxide SiOx≈1. Thermal treatment using rapid thermal processing and oven annealing requires annealing times of few tens of sec. up to few tens of min. However, in a thin film technology the phase separation of SiOx at high temperatures requires a very rapid thermal processing of few tens of ms in order to avoid substrate damage.
Here, the structure of the Si-SiO2 nanocomposite was investigated by energy-filtered transmission electron microscopy (EFTEM), EFTEM tomography and atom probe tomography, which revealed a percolated Si morphology. This is in excellent agreement with atomistic simulations using kinetic Monte-Carlo method. Depending on the annealing time and temperature a feature size in the range of 2...5 nm was found, which is small enough for band gap widening due to quantum confinement.
We show that the favorable properties of Si-SiO2 nanocomposite, e.g. quantum size effect and percolated morphology, make it a suitable material for PV absorber.

Keywords: sponge-like nanocomposite; SiOx; photovoltaic; absorber; phase separation; band-gap engineering

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Permalink: https://www.hzdr.de/publications/Publ-20668
Publ.-Id: 20668