Experimental determination of minority carrier lifetime and recombination mechanisms in MCT photovoltaic detectors

This paper presents an experimental study of minority carrier lifetime and recombination mechanisms in HgCdTe photodiode. The excitation light source is a wavelength-tunable pulsed infrared laser. A constant background illumination has been introduced to minimize the effect of the junction equivalent capacitor and the equivalent series resistance. The slow decay of the photo-generated voltage is recorded by a storage oscilloscope. By fitting the exponentially decay curve, the time constant has been obtained which is regarded as the photo-generated minority carrier lifetime of the HgCdTe photodiode. The experimental results show that the carrier lifetime is in the range of 18 ~ 407 ns at 77 K for the measured detectors of four compositions. It was found that the Auger recombination process is more effective for low Cd composition while the radiative recombination process became more important for high compensated materials. The Shockley-Read-Hall (SRH) recombination processes could not be ignored for all Cd composition.