Visible to near-infrared photodetector based on SnSe <sub>2</sub> /WSe <sub>2</sub> heterojunction with potential application in artificial visual neuron
Yang Sun, Ruixue Hu, Chunhua An, Xinli Ma, Jing Zhang, Jing Liu
Abstract
Abstract Two-dimensional (2d) transition-metal dichalcogenides (TMDCs) are promising candidate materials for developing next generation nano optoelectronic devices, due to their strong interaction with light. In addition, the free of surface dangling bonds makes it possible to stacking any different types of 2D TMDCs together to form heterojunctions with desirable band structures for various applications. However, most of the 2D TMDCs are bipolar or strong unipolar n-type doped, while very few of them show weak p-type doping, which severely affects the performance of the formed heterojunctions. In this work, we fabricated a SnSe 2 /WSe 2 heterojunction of type II band alignment with a small bandgap of ∼0.1 eV, which is ideally for developing optoelectronic devices responsible to a broad light spectrum. N 2 O plasma treatment is applied to enhance the p-type doping of both WSe 2 and SnSe 2 , which results in the increased on–off ratio of n-type SnSe 2 by 50 times and the hole mobility of WSe 2 by 527 times. The WSe 2 /SnSe 2 heterostructure also achieves a decent performance as a p–n junction, which exhibits photo responsivity of 450 mA W −1 and 133 mA W −1 for 700 nm visible light and 1600 nm infrared light, respectively, without any gate or source-drain bias, showing great photovoltaic effect. Moreover, the heterojunction shows great promise as an artificial visual neuron, which can differentiate the dark, visible and infrared light illumination conditions by applying a series of electrical pulses through the back-gate electrode.