High-performance graphene-enhanced HgCdTe mid-wave infrared photodetector development

Conventional photodetectors based on HgCdTe material and designed to absorb mid-wave infrared (MWIR) band wavelengths typically require cryogenic or at minimum thermoelectric cooling to maintain adequate levels of infrared (IR) sensing performance. This cooling requirement invariably entails augmentations in size, power, and cost, which for space and satellite applications such as remote sensing and earth observation generally are limiting in scope and potentially prohibitive. Here we report a scalable, low cost, low power, and small footprint room temperature operating MWIR sensing device involving the integration of bilayer graphene functioning as a high mobility channel with HgCdTe material, to limit the recombination of photogenerated carriers and achieve higher performance detection over the 2-5 mu m MWIR without the need of an additional cooling mechanism. For the development of these graphene-enhanced HgCdTe MWIR photodetectors, graphene bilayers on Si/SiO2 substrates were doped with boron using a spin-on dopant (SOD) process, and then transferred onto HgCdTe substrates for enhanced higher-mobility photodetection. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and secondary-ion mass spectroscopy (SIMS) were employed to analyze dopant levels and structural properties of the graphene through various stages of the development process and characterize the p-doped graphene following doping and transfer. The features and enhanced performance of the room-temperature operating graphene-based HgCdTe MWIR detectors were demonstrated through modeling, material characterization, and measurements of detector IR sensitivity and response performance.