Doping and Transfer of High Mobility Graphene Bilayers for Room Temperature Mid-Wave Infrared Photodetectors

Abstract

High-performance graphene-HgCdTe detector technology has been developed combining the best properties of both materials for mid-wave infrared (MWIR) detection and imaging. The graphene functions as a high mobility channel that whisks away carriers before they can recombine, further contributing to detection performance. Comprehensive modeling on the HgCdTe, graphene, and the HgCdTe-graphene interface has aided the design and development of this MWIR detector technology. Chemical doping of the bilayer graphene lattice has enabled p-type doping levels in graphene for high mobility implementation in high-performance MWIR HgCdTe detectors. Characterization techniques, including SIMS and XPS, confirm high boron doping concentrations. A spin-on doping (SOD) procedure is outlined that has provided a means of doping layers of graphene on native substrates, while subsequently allowing integration of the doped graphene layers with HgCdTe for final implementation in the MWIR photodetection devices. Successful integration of graphene into HgCdTe photodetectors can thus provide higher MWIR detector efficiency and performance compared to HgCdTe-only detectors. New earth observation measurement capabilities are further enabled by the room temperature operational capability of the graphene-enhanced HgCdTe detectors and arrays to benefit and advance space and terrestrial applications.

High-performance graphene-enhanced HgCdTe photodetectors for uncooled extended infrared band sensing and imaging

“…This MWIR detector device presented in Figure 2 comprises three principal layers: (1) A layer of CdTe is deposited on a silicon substrate to act as a buffer layer, where the combined Si substrate and subsequent CdTe layer function as the gate terminal which provides an electrical field in the "vertical" direction into the detector heterostructure and aids in carrier transport in that direction. (2) The HgCdTe absorber layer subsequently grown on top of the silicon substrate and CdTe buffer layer acts as the active optical layer where photogeneration of carriers takes place. The absorber material and its physical properties such as its bandgap determine the sensitivity of the absorber layer to the detection wavelength window, as well as the photogeneration rate, quantum efficiency, and carrier lifetime.…”

“…Detection of mid-wave infrared (MWIR) radiation is beneficial for applications including long-range imaging and early threat detection, and also useful for detecting and measuring natural features including sea surface temperature, cloud properties, volcanic activities, and forest fires. 1,2 The 2-5 μm MWIR spectral band is similarly suitable for various NASA Earth Science applications. 3,4 Using low size, weight, power, and cost MWIR sensors on smaller platforms in space can provide improved measurement and mission capabilities.…”

High-performance graphene-enhanced HgCdTe photodetectors for uncooled mid-wave infrared sensing

“…Detection of mid-wave infrared (MWIR) radiation is beneficial for applications including long-range imaging and early threat detection. 1 It is also useful for detecting and measuring natural features including sea surface temperature, cloud properties, volcanic activities, and forest fires. The 2-5 μm MWIR spectral band is likewise suitable for a variety of NASA Earth Science applications.…”