A high-accuracy calibration method for temperature dependent photoluminescence imaging

Abstract

This work demonstrates a novel technique for calibrating temperature dependent photoluminescence (PL) images of silicon wafers with high accuracy. The PL signal is calibrated using a heat-controlled photoconductance (PC) stage integrated into the PL imaging system. The PC signal is measured in true steady state condition and used to determine the calibration constant under the same temperature and illumination as the PL image, thus providing a high-precision calibration. This results in a robust method for imaging of important physical parameters, such as the minority carrier lifetime and the implied voltage at different temperatures, as well as the temperature coefficients and the recombination parameter γ. The method is verified through comparison with a similar PL imaging system, where the calibration is made from a conventional flash-based quasi-steady-state PC measurement. Finally, the method is applied to compensated multicrystalline silicon wafers, demonstrating the usefulness of the proposed calibration routine for analysing complex materials.