Surface impact on carrier lifetime of narrow-gap HgCdTe by injection-dependent mid-infrared photoluminescence decay

Surface recombination of HgCdTe limits the carrier lifetime and hence the photoresponse performance of the infrared detector. Understanding the contribution of surface effects to carrier lifetime has long been a topic of interest. In this work, we investigate the injection-dependent carrier lifetime of mid-infrared HgCdTe with different layer thicknesses by photoluminescence decay measurements. A pronounced carrier lifetime reduces as the injection level lowers in the surface-unpassivated HgCdTe, while the lifetime reduction is absent in the surface-passivated sample. This behavior cannot be attributed to the bulk recombination but is primarily caused by the surface effect. A semiquantitative model is established to separate the contributions of surface and bulk recombination, and therefore, the surface recombination velocity and bulk lifetime are successfully achieved. The results may contribute to the surface optimization of narrow-gap HgCdTe for the performance enhancement of an infrared detector.