Injection dependence of the effective lifetime of n-type Si passivated by Al₂O₃

An edge effect?

authored by

Boris Veith, Tobias Ohrdes, Florian Werner, Rolf Brendel, Pietro P. Altermatt, Nils Peter Harder, Jan Schmidt

Abstract

Aluminum oxide provides an excellent surface passivation on p- and n-type crystalline silicon. On n-type silicon, however, the effective excess carrier lifetime τ_eff is often found to be injection dependent. Our experimental results show that, in our case, this effect depends mainly on the size of the lifetime samples. The fixed negative charges present at the Al ₂O₃/c-Si interface induce an inversion layer at the surface, which results in a p-n-junction close to the surface of the sample and the inversion layer couples the sensing area with the poorly passivated or damaged edge of the sample. For smaller samples stronger injection-dependent lifetimes are measured, whereas large samples show a smaller injection dependence. In addition, photoconductance-calibrated photoluminescence lifetime images show that for low injection levels the lifetime decreases towards the sample edge. Device simulations for different sample sizes including the edge recombination are in agreement with the measured injection-dependent lifetimes. Therefore, it is necessary to use sufficiently large samples or decouple the sensing area form the edge when evaluating the injection dependence of the lifetime. For the samples used in this contribution, the injection dependence of the lifetime did not even fully vanish for an edge length of 12.5 cm.

Organisation(s)

Institute of Solid State Physics

External Organisation(s)

Institute for Solar Energy Research (ISFH)

Type

Article

Journal

Solar Energy Materials and Solar Cells

Volume

120

Pages

436-440

No. of pages

5

ISSN

0927-0248

Publication date

2014

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Renewable Energy, Sustainability and the Environment, Surfaces, Coatings and Films

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1016/j.solmat.2013.06.049 (Access: Unknown)