Development of graphene-enhanced HgCdTe photodetectors for uncooled mid-wave infrared detection

Abstract

The development of a scalable, low cost, low power, and room temperature operating MWIR detector technology capable of high spatial resolution infrared (IR) imaging is of substantial interest and utility towards the advancement of space and satellite technologies, including remote sensing and earth observation capabilities. However, conventional mid-wave infrared (MWIR) band photodetectors based on HgCdTe material typically require external cooling to achieve sufficient sensing performance, adding significant size, weight, and power restrictions and requirements. By incorporating bilayers of <i>p</i>⁺-doped graphene to function as a high mobility channel enhancing recombination of photogenerated carriers within HgCdTe absorbing material, a graphene-enhanced HgCdTe photodetector capable of providing uncooled detection over the 2-5 μm MWIR band has been developed. This high performance MWIR band detector technology comprises graphene bilayers initially deposited on Si/SiO₂ doped with boron and annealed using a spin-on dopant (SOD) process, that are subsequently transferred onto HgCdTe. Raman spectroscopy, secondary-ion mass spectroscopy (SIMS), and I-V photocurrent testing were used to analyze dopant levels, structural properties of the bilayer graphene prior to and following doping and transfer, and detector IR photoresponse, respectively, of the graphene-enhanced detector devices through various stages of the development process. These room-temperature operating graphene-HgCdTe MWIR detectors have demonstrated enhanced MWIR detection performance to benefit certain NASA Earth Science, defense, and commercial applications.