Journal of Spectral Imaging,   Volume 5   Article ID a8   (2016)

Peer reviewed paper

Hyperspectral photoluminescence imaging of defects in solar cells

Ingunn Burud,a,* Torbjørn Mehl,a Andreas Flo,a Dominik Lauschb and Espen Olsena
aNorwegian University of Life Sciences, Department of Mathematical Sciences and Technology, Campus Ås, Pb 5003, 1433 Ås, Norway. E-mail: [email protected]
bFraunhofer-Center für Silizium Photovoltaik CSP Otto-Eißfeldt-Straße 12, 06120 Halle (Saale), Germany

The present work is a demonstration of how near infrared (NIR) hyperspectral photoluminescence imaging can be used to detect defects in silicon wafers and solar cells. Chemometric analysis techniques such as multivariate curve resolution (MCR) and partial least squares discriminant analysis (PLS-DA) allow various types of defects to be classified and cascades of radiative defects in the samples to be extracted. It is also demonstrated how utilising a macro lens yields a spatial resolution of 30 µm on selected regions of the samples, revealing that some types of defect signals originate in grain boundaries of the silicon crystal, whereas other signals show up as singular spots. Combined with independent investigation techniques, hyperspectral imaging is a promising tool for determining origins of defects in silicon samples for photovoltaic applications.

Keywords: near infrared, photovoltaic, multicrystalline silicon, MCR, PLS-DA