Hole-dominated Fowler-Nordheim tunneling in 2D heterojunctions for infrared imaging.

Heterostructures based on diverse two-dimensional (2D) materials are effective for tailoring and further promoting device performance and exhibit considerable potential in photodetection. However, the problem of high-density thermionic carriers can be hardly overcome in most reported heterostructure devices based on type I and type II band alignment, which leads to an unacceptably small Iphoto/Idark and strong temperature dependence that limit the performance of photodetectors. Here, using the MoTe2/h-BN/MoTe2/h-BN heterostructure, we report the hole-dominated Fowler-Nordheim quantum tunneling transport in both on and off states. The state-of-the-art device operating at room temperature shows high detectivity of >108 Jones at a laser power density of <0.3 nW µm-2 from the visible to near infrared range. In addition, the fast on-off switching and highly sensitive photodetection properties promise superior imaging capabilities. The tunneling mechanism, in combination with other unique properties of 2D materials, is significant for novel photodetection.

Stable mid-infrared polarization imaging based on quasi-2D tellurium at room temperature.

Next-generation polarized mid-infrared imaging systems generally requires miniaturization, integration, flexibility, good workability at room temperature and in severe environments, etc. Emerging two-dimensional materials provide another route to meet these demands, due to the ease of integrating on complex structures, their native in-plane anisotropy crystal structure for high polarization photosensitivity, and strong quantum confinement for excellent photodetecting performances at room temperature. However, polarized infrared imaging under scattering based on 2D materials has yet to be realized. Here we report the systematic investigation of polarized infrared imaging for a designed target obscured by scattering media using an anisotropic tellurium photodetector. Broadband sensitive photoresponse is realized at room temperature, with excellent stability without degradation under ambient atmospheric conditions. Significantly, a large anisotropic ratio of tellurium ensures polarized imaging in a scattering environment, with the degree of linear polarization over 0.8, opening up possibilities for developing next-generation polarized mid-infrared imaging technology.