High Operating Temperature Graphene Enhanced Charge Coupled Hetero-Structure for Infrared Focal Plane Arrays

The Proposed Phase I SBIR Program with the US Army will focus on design, development and demonstration of High Operating Temperature Graphene Enhanced Charge Coupled Hetero-Structure for Infrared Focal Plane Arrays. We plan to apply the innovative approach using graphene on HgCdTe to develop MWIR detectors, and subsequently Focal plane arrays that will operate near room temperature while maintaining the state-of-the-art performance in HgCdTe quantum detectors. We will investigate various grating geometries in the HgCdTe-Graphene device to demonstrate high performance. We will explore theoretically and experimentally surface patterning methodologies to enhance light absorption in thin films of HgCdTe, the key material used in state-of-the-art performance infrared quantum detectors. Our goal is to develop mid-wave infrared (MWIR) detectors that can operate near room temperature, by using thin absorbing layers and employing effective charge extraction with graphene. We will investigate the feasibility of placing broadband plasmonic resonators on the surface to enhance light trapping while mitigating the impedance mismatch. Low-loss plasmonic materials such as SiC for use in the MWIR wavelengths will be evaluated. At wavelengths longer than the plasmonic resonance, the transmission of light into the absorbing medium is enhanced. This is because they preferentially scatter light into the high refractive index substrate, resulting in enhanced coupling to the absorbing layer underneath. We will theoretically investigate the effect of particle size and the array period on top of the HgCdTe film to assess the light trapping and antireflection effects. An additional thin spacer layer, of Si3N4, will be evaluated. While theoretically identifying the most promising approaches to enhance absorption in thin HgCdTe films, we will also explore development of a low-cost, fabrication process that integrates graphene layers and Grating on top of graphene/HgCdTe heterointerfaces. This may increase the absorbing volume and eliminates the need of HgCdTe surface passivation after etching. Finally, design methods developed for HgCdTe can be extended to type II superlattice detectors operating in the same MWIR range.