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Measuring the bulk lifetime of unpassivated blocks and ingots is of great interest to the solar cell industry. The eddy‐current photoconductance method is a common choice for such measurements, employing the quasi‐steady‐state (QSS) mode for lower lifetime samples, and the transient photoconductance decay (PCD) mode for higher lifetime samples. Due to the high surface recombination velocity in unpassivated bulk samples, the lifetime measured with this method consists of components of recombination at both the surface and in the bulk. In order to determine the bulk lifetime from the measurement data, simulations of both transient and QSS mode measurements were conducted. Copyright © 2010 John Wiley & Sons, Ltd.

Excess-carrier recombination lifetime is a key parameter in silicon solar cell design and production. With the vast international use and recent standardization (SEMI PV13) of eddy-current wafer and brick silicon lifetime test instruments, it is important to quantify the inter- and intra-laboratory repeatability. This paper presents results of an international inter-laboratory study conducted with 24 participants to determine the precision of the SEMI PV13 eddy-current carrier lifetime measurement test method. Overall, the carrier recombination lifetime between-laboratory reproducibility was found to be within ±11% for quasi-steady-state (QSS) mode and ±8% for transient mode for wafer samples and within ±4% for bulk samples

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Photoconductance measurements have been one of the most common ways to measure the lifetime in silicon for over 60 years. Since 1985, the most common method for doing calibrated lifetime measurements is using an eddy-current sensor to monitor photoconductance as a function of time and illumination, providing data that can be interpreted in terms of carrier density and hence lifetime. Here we present recent extensions to this measurement technique that have generalized the method. Bulk lifetime measurements on industrial samples are presented. The information available from the effects of grain boundaries on eddy-current measurements are summarized. Recent applications for the use of these instruments for measurement of mobility in compensated materials are also described.

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High efficiency silicon solar cells demand the use of high lifetime silicon wafers. Characterization of boules and bricks before wafering allows poor quality material to be rejected before expensive processing steps. This paper extends simulation techniques previously used in quasi-steady-state-photoconductance to transient photoconductance decay measurements of high lifetime bulk samples. Simulated photogenerated carrier density profiles allow estimation of the bulk lifetime of a thick silicon sample with high surface recombination velocity.

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