Weak variband surface layers as an effective means of protection from the surface recombination of photoexcited carriers in infrared threshold CdHgTe photoresistors

Abstract

It is demonstrated that variband near-surface layers with even a small composition gradient can provide ultimate photomodulation (corresponding to the absence of the surface recombination) of the conductivity of thin CdHgTe samples used for manufacturing threshold photoresistors (including those of the SPRITE type) for the wavelengths λ =8−12 μm and λ=3−5 μm. This is explained by the formation (even in weak variband layers) of a special profile of the photoexcited carrier distribution that inhibits their diffusion to the surface. As is known, the introduction of the near-surface variband layers with a small composition gradient must not lead to any substantial increase in the number of defects in the sample.