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 minority-carrier lifetime and surface recombination velocity in silicon is proposed. A pig-tailed 1.55 μm CW laser diode is used to detect the transient of the excess carriers generated by a short Nd:YAG laser pulse. The probe beam is launched parallel to the sample surface while the pump beam uniformly illuminates the sample perpendicular to its surface. Separation between bulk lifetime and surface recombination velocity is achieved by performing the measurement on samples of different thickness. Experimental results indicate that separation of bulk and surface contribution is feasible in a wide range of surface recombination velocities thus making this method suitable to investigate the effects of surface passivation techniques.