Dresden 2014 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 71: Energy materials: Silicon-based photovoltaics
HL 71.2: Talk
Wednesday, April 2, 2014, 15:15–15:30, POT 151
Passivation of Silicon surfaces by Aluminum oxide layers: a DFT simulation study — •Francesco Colonna1,2 and Christian Elsässer1,2 — 1Albert-Ludwigs University, Freiburg Materials Research Center (FMF), Freiburg, Germany — 2Fraunhofer IWM, Freiburg, Germany
By the Atomic Layer Deposition of Aluminum oxide on a Silicon (100) surface, followed by a heat-treatment, it is possible to obtain an excellent surface passivation [1], which is expected to play a significant role in future photovoltaic application.
In the present study we investigate the interplay between the electronic structure at the interface and the local atomic environments of Aluminum oxide by means of density functional theory (DFT) simulation methods. Observations show that passivation is associated with a change in the proportion of local tetrahedral and octahedral cation coordination in the passivation layer. We model a number of stoichiometric or oxygen-rich interfaces between Silicon and k-Alumina, which entails both tetrahedra and octahedra. We also study the role played by additional Hydrogen at the interface. We relate the local features of the interface to the presence of electronic defect levels in the band gap, as computed by means of a self-interaction corrected [2] local-density approximation of DFT.
[1] G. Agostinelli et al., Solar Energy Materials and Solar Cells 90 (18-19), 3438-3443 (2006). [2] W. Körner and C. Elsässer, Physical Review B 81, 085324 (2010).