A gate-free monolayer WSe<sub>2</sub> pn diode.

Chen, Jhih-Wei; Lo, Shun-Tsung; Ho, Sheng-Chin; Wong, Sheng-Shong; Vu, Thi-Hai-Yen; Zhang, Xin-Quan; Liu, Yi-De; Chiou, Yu-You et al. · Nat Commun · 2018

basic_science · Level V

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Abstract

Interest in bringing p- and n-type monolayer semiconducting transition metal dichalcogenides (TMD) into contact to form rectifying pn diode has thrived since it is crucial to control the electrical properties in two-dimensional (2D) electronic and optoelectronic devices. Usually this involves vertically stacking different TMDs with pn heterojunction or, laterally manipulating carrier density by gate biasing. Here, by utilizing a locally reversed ferroelectric polarization, we laterally manipulate the carrier density and created a WSe<sub>2</sub> pn homojunction on the supporting ferroelectric BiFeO<sub>3</sub> substrate. This non-volatile WSe<sub>2</sub> pn homojunction is demonstrated with optical and scanning probe methods and scanning photoelectron micro-spectroscopy. A homo-interface is a direct manifestation of our WSe<sub>2</sub> pn diode, which can be quantitatively understood as a clear rectifying behavior. The non-volatile confinement of carriers and associated gate-free pn homojunction can be an addition to the 2D electron-photon toolbox and pave the way to develop laterally 2D electronics and photonics.