What is it about?

Mercury-cadmium-telluride (MCT) based infrared photodetectors (IR PDs) require bulky and costly cryogenic cooling to reduce noise and maintain a good signal-to-noise ratio. Noise can be reduced by reducing the MCT layer thickness without affecting absorption efficiency and photocarrier generation. In our proposed scheme, we integrate resonant dielectric grating (RWG) with a thin (1.5 µm) MCT absorbing layer to enhance absorption and photocarrier generation that is comparable to a bulk 5 µm thick MCT layer without RWG. A ~3x reduction in the MCT layer thickness without compromising the absorption has the potential for realizing infrared (IR) photodetectors (PDs) with improved sensitivity at conventional and/or elevated operating temperatures.

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Why is it important?

This work highlights the beneficial aspect of increasing a lateral optical path by leveraging the diffraction phenomenon from a dielectric grating. This potentially helps reduce absorber layer thickness towards reducing volumetric thermal noise in an infrared photodetector.

Perspectives

I hope that integrating a thin absorbing layer and a dielectric grating paves the way towards a higher operating temperature (HOT) detector scheme that will widen the scope of applications for infrared FPAs, such as in CubeSats, which require small payload and budget constraints.

Mohammad Sojib
Virginia Commonwealth University

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This page is a summary of: All-dielectric grating-assisted absorption enhancement in a subwavelength mercury cadmium telluride layer for infrared photodetectors, Journal of Applied Physics, April 2024, American Institute of Physics,
DOI: 10.1063/5.0196982.
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