Determination of minority carrier lifetime in mercury-cadmium telluride photovoltaic detectors using parallel resistance method

This paper presents a minority carrier lifetime extraction method using transient photovoltage method. The excitation light source is a picosecond pulsed infrared laser. A parallel resistance has been introduced to minimize the effect of the equivalent junction series resistance effect. A storage oscilloscope has been used to record the photovoltage of the photodiode. By fitting the exponentially decay curve, the time constant has been obtained which is regarded as the photo-generated minority carrier lifetime of the photodiode. The experimental results show that the carrier lifetime is in the range of 0.7~110 ns at 77 K for the measured detectors of four compositions. The results indicate that the lifetime become longer with the increase of Cd composition.