The GLM™-2000 Minority Carrier Lifetime Monitor is a precision instrument that uses a patented transformer coupled photoconductance method to simultaneously measure True Steady State Minority Carrier Lifetimes (Gtau), Photoconductance Rise and Decay and Sheet Resistance. It takes existing industry-accepted metrology methodology and combines them with high speed electronics, solid state illumination technology, noise rejection, and robust recipe driven software which results in an instrument that is easy to operate and provides simple to understand, accurate and repeatable results.
The quality of silicon used for crystal silicon PV cells has a direct influence on the quality, or conversion efficiency, of the final product (solar cells). The objective is to transfer as much of the incoming energy, or carriers, to the output of the circuit or cell. This is achieved, in part, by minimizing any recombination of the carriers. Carriers recombine when they come in touch with defects or impurities in the silicon. Recombination reduces the potential output current from the cell.
Measuring minority carrier lifetime is a way to quantitatively assess the quality of the base silicon, since lower minority carrier lifetime is an indication of impurities and defects in the silicon. Additionally, measuring sheet resistance and Photoconductance Decay (PCD) give further information on surface recombination effects and the quality of the PV cell manufacturing process from as-cut inspection through ARC deposition.
