A Gate-Free Monolayer WSe2 pn Diode

Jhih-Wei Chen^1*, Chia-Hao Chen², Chung-Lin Wu¹

¹Department of Physics, National Cheng Kung University, Tainan, Taiwan
²National Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Jhih-Wei Chen, email:z10503046@email.ncku.edu.tw

Monolayer transition-metal dichalcogenides (TMDs) are known to be one of the most promising candidates for future nanoelectronic and nanooptoelectronic devices owing to their outstanding electrical and optical properties. Interest in bringing p- and n-type monolayer semiconducting 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 WSe₂ pn homojunction on the supporting ferroelectric BiFeO₃ substrate. This non-volatile WSe₂ pn homojunction is demonstrated with optical and scanning probe methods, scanning photoelectron micro-spectroscopy (SPEM), and transport measurement. A homo-interface is a direct manifestation of our WSe₂ 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.

Keywords: TMDs, pn heterojunction, Gate-free pn homojunction, Nonvolatile