Impact of Carrier Profile and Rear-Side Reflection on Photoluminescence Spectra in Planar Crystalline Silicon Wafers at Different Temperatures

Abstract—The increasing use of spectral photoluminescence as an advanced and accurate diagnostic tool motivates a comprehen-sive assessment of the effects of some important optical and electri-cal properties on the photoluminescence spectra from crystalline silicon wafers. In this paper, we present both modeling results and measurements to elucidate the effects of the internal reflectance at the planar wafer surfaces, as well as the carrier profile varying across the sample thickness due to an increased rear-surface re-combination velocity, as a function of temperature. These results suggest that the accuracy of existing spectral PL techniques may be improved by using higher temperatures due to the increased effect of the carrier profile at higher temperatures. They also show that changes in the photoluminescence spectrum shape caused by the addition of a rear-side specular reflector offset those caused by changes in the carrier profile due to increased rear surface re-combination, and therefore, considerable care needs to be taken when changing the rear-side optics. Finally, the possible impact of variations in the rear-side reflectance on the band–band ab-sorption coefficient and radiative recombination coefficient, which have previously been determined using the spectral photolumines-cence technique, is assessed and demonstrated to be insignificant in practice. Index Terms—Absorption, charge carrier density, photovoltaic cells, photoluminescence (PL), radiative recombination, silicon. I