Berlin 2012 – scientific programme

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DS: Fachverband Dünne Schichten

DS 8: Thin film photovoltaics: oxides and nanostructures

DS 8.1: Talk

Monday, March 26, 2012, 16:30–16:45, H 2032

Si-nanosponge embedded in SiO₂ as a new absorber material for photovoltaics — •Bartosz Liedke¹, Karl-Heinz Heinig¹, Bernd Schmidt¹, David Friedrich¹, Arndt Mücklich¹, Jeffrey Kelling¹, and Dirk Hauschild² — ¹Helmholtz-Zentrum Dresden-Rossendorf , 01314 Dresden, Germany — ²LIMO Lissotschenko Mikrooptik GmbH, 44319 Dortmund, Germany

Silicon based nanostructures became within the last years most promising material for the PV market. Quantum confinement effect of nanostructured silicon allows for band gap engineering just by size manipulation to absorb the light in more efficient way.

Here, we consider SiO_x layers fabricated by magnetron co-sputter deposition, which after thermal treatment decompose into a network of Si nanowires embedded in SiO₂. The thermally activated spinodal decomposition is performed by rapid thermal processing within a few seconds and by very rapid thermal processing within several ms using diode laser. The morphology and crystallinity of the Si-nanosponge was measured by energy filtered TEM and Raman, respectively. The details of decomposition are studied using the atomistic kinetic Monte-Carlo (KMC) simulations at different concentrations defined by the x parameter. The spatiotemporal temperature profiles T(x, t) of the scanned laser has been calculated as a function of thickness and time by the heat transport equation. The obtained profiles are used in the KMC. The combined theoretical and experimental investigations support the band gap engineering of the Si-nanosponge absorber via a control of the quantum confinement.