Current-voltage characteristics of silicon solar cells: Determination of Base Doping Concentration and Hysteresis Correction

The measurement of the current-voltage (IV) characteristics is the most important step for quality control and optimization of the fabrication process in research and industrial production of silicon solar cells. The occurrence of transient errors and hysteresis effects in IV-measurements can hamper the direct analysis of the IV-data of high-capacitance silicon solar cells. We propose a novel procedure to reconstruct a quasi-steady-state (qss) IV-characteristics from hysteretic measurements by aligning the generalized current density of forward and backward sweeps. In the process, the base doping concentration NB and the cell thickness d are used as optimization parameters and calculated alongside the qss-IV-curve. We summarize the theory behind the method, describe the experimental implementation and verify the applicability of the approach by comparing the extracted doping concentration to multiple alternative methods. For a test set of more than 100 silicon heterojunction solar cells with doping concentrations between 3 and 7∙1015 cm-3 a RMSD <3.4∙1014 cm-3 is achieved. Basic parameter extraction from the qss-IV-curve closely match reference values with a RMSD <0.1 %abs in efficiency and fill factor.