Imaging the Recombination Current Pre-Factor Jo of Heavily Doped Surface Regions; A Comparison of Low and High Injection Photoluminescence Techniques

27th European Photovoltaic Solar Energy Conference and Exhibition; 1312-1318
A novel technique for imaging the recombination current pre-factor Jo of heavily doped surface regions, ubiquitous to mainstream silicon solar cells, is introduced. This technique utilises photoluminescence in a low injection regime, allowing measurement of test structures with low and moderate resistivities, which are unattainable by the conventional Kane and Swanson method [1]. The procedure is fast and simple requiring only one photoluminescence image and no photoconductance measurement (after an initial calibration). The potential of the technique is demonstrated on surface-passivated phosphorus diffusions with sheet resistances in the range of ~15 – 120 Ω/sq. A comparison is made with both high and low injection photoconductance decay (PCD) measurements and a recently proposed high injection Jo imaging technique (based on Kane and Swanson theory) [2, 3].