Temperature dependent photoluminescence imaging calibrated by photoconductance measurements

Abstract

In this paper we present a novel method for measuring temperature dependent lifetime images with high spatial resolution using photoconductance calibrated photoluminescence (PL) imaging. In order to achieve this, PL images are recorded at various temperatures by implementing a temperature stage into a commercial, steady state PL imaging setup. Carrier lifetime images are then calculated from the detected PL intensity, based on quasi-steady state photoconductance calibration measurements performed at the same temperatures that are used for the PL images. By analysing the carrier lifetime data as a function of injection level and temperature, this method allows for in-depth, spatially resolved defect characterization of Si wafers. Such temperature dependent lifetime data are also useful as input for device simulations of the temperature coefficient of solar cell efficiency. The uses of the method are illustrated with different examples based on commercial high performance multicrystalline Si wafers.