Shanghai Institute of Technology has proposed a unipolar barrier infrared photodetector based on vdW materials for the first time which breaks through the limitation of lattice matching and band matching in traditional materials. The vdW unipolar barrier structures as majority-blocking structures block undesirable dark current without suppressing photocurrent to improve the sensitivity and operating temperature of the infrared photodetectors. At room temperature, the peak specific detectivity in the mid-wavelength infrared reaches 2.3×10¹⁰ cm Hz^1/2 W^-1  under the blackbody source. So far, only a few infrared photodetectors made from two-dimensional materials can realize blackbody detection. This work has made a great breakthrough in the field of room-temperature infrared photodetectors made from two-dimensional materials. The result was published in Nature Electronics titled "Unipolar Barrier photodetectors based on van der Waals Heterostructures".

Further, in the field of motion detection, the researchers have constructed a more complex three-dimensional vertically stacked van der Waals heterojunction and proposed an "ALL IN ONE" device, which is a prototype device integrating detection, storage and computation. By using a bipolar and visible/near-infrared sensitive tungsten selenide as a floating gate, the positive and negative optical storage properties can be obtained in a single device through the electron-hole dual storage mode. The linearity of positive and negative multi-state storage is achieved. The positive and negative multi-state storage corresponds to the ON/OFF characteristics of retinal neural networks. Based on this type of retinal neural network, the temporal differential processing capability of the "ALL IN ONE" device is demonstrated, and the first demonstration of moving target detection is realized. The result was published in Nature Nanotechnology titled "All-in-one two-dimensional retinomorphic hardware device for motion detection and recognition".

The above works are supported by the National Natural Science Foundation of China, Ministry of Science and Technology of China, Chinese Academy of Sciences, Shanghai Science and Technology Commission.

Link to the papers:

https://www.nature.com/articles/s41928-021-00586-w

https://www.nature.com/articles/s41565-021-01003-1