AN OPTICAL TECHNIQUE TO MEASURE THE BULK LIFETIME AND THE SURFACE RECOMBINATION VELOCITY IN SILICON SAMPLES BASED ON A LASER-DIODE PROBE SYSTEM

A high sensitivity, pump-probe optical method to measure the bulk mino rity-carrier lifetime and surface recombination velocity in silicon is proposed. A pig-tailed 1.55 mu m CW laser diode is used to detect the transient of the excess carriers generated by a short Nd:YAG laser pu lse. The probe beam is launched parallel to the sample surface while t he pump beam uniformly illuminates the sample perpendicular to its sur face. Separation between bulk lifetime and surface recombination veloc ity is achieved by performing the measurement on samples of different thickness. Experimental results indicate that separation of bulk and s urface contribution is feasible in a wide range of surface recombinati on velocities thus making this method suitable to investigate the effe cts of surface passivation techniques. (C) 1998 Elsevier Science Ltd. All rights reserved.