Sensitivity Analysis of Eddy Current Excess Carrier Recombination Lifetime Measurements Due to Input Parameter Uncertainty

Abstract

For decades, excess carrier recombination lifetime measurements using an eddy current photoconductance sensor have been essential in characterizing the quality of silicon photovoltaic samples prior to metallization. Key metrics reported from the analysis of these measurements include injection-dependent excess carrier recombination lifetime, emitter saturation current density, bulk lifetime, and the implied current–voltage curve. These metrics are crucial for process control, optimization, and technological advancements in photovoltaic research and development, as well as production. As modern high-efficiency cell designs increasingly rely on precise determination of these metrics, it is important to quantify their uncertainty due to all factors; this study specifically examines their sensitivity to uncertainties in the sample-specific input parameters required for their reporting. Overall, results with a high level of confidence, including less than 1-fA/cm² uncertainty in emitter saturation current density and less than 1-mV uncertainty in implied ${V}_{\mathrm{oc}}$, can be achieved with knowledge of the input thickness and substrate resistivity beyond what is specified on a wafer specification sheet.