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 I_photo/I_dark 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.