Two-Dimensional Lateral Multiheterostructures Possessing Tunable Band Alignments

Controllable growth, band-alignment engineering, and accurate electronic-structure evaluation are very important for manipulating the physical properties and customizing the potential optoelectronic applications of two-dimensional heterostructures. Herein, a series of lateral WS2-WS2(1-x)Se2x -WSe2 multiheterostructures having atomically sharp interfaces and tunable band alignments were synthesized using a well-designed one-step source-switched physical vapor deposition method. By controlling the chemical composition of the WS2(1-x)Se2x alloy at the middle region, the band alignments and conduction types of the WS2-WS2(1-x)Se2x -WSe2 multiheterostructures could be effectively modulated. The sharp one-dimensional junction interfaces of the WS2-WS2(1-x)Se2x -WSe2 multiheterostructures were characterized by using microphotoluminescence and scanning transmission electron microscopy. Furthermore, the work function differences, energy band gaps, and electronic-structure of the lateral WS2-WS2(1-x)Se2x -WSe2 multiheterostructure were accurately measured using nanoangle-resolved photoemission spectroscopy. Based on our experimental results, an accurate and reliable type-II band-alignment diagram was depicted for the WS2-WS2(1-x)Se2x -WSe2 multiheterostructure. This work confirms the possibility for controlling band alignments in two-dimensional lateral multiheterostructures, which represents a key feature for designing optoelectronic devices.