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Journal Article
Bandgap Tuned WS2 Thin-Film Photodetector by Strain Gradient in van der Waals Effective Homojunctions
- Authors
- Seong Jun Kim, Dongwook Kim, Bok Ki Min, Yoonsik Yi, Shuvra Mondal, Van-Tam Nguyen, Jeongwoon Hwang, Dongwoo Suh, Kyeongjae Cho, Choon-Gi Choi
- Issue Date
- 2021-11
- Citation
- Advanced Optical Materials, v.9 no.22, pp.1-10
- ISSN
- 2195-1071
- Publisher
- Wiley
- Language
- English
- Type
- Journal Article
- Project Code
- 21PB4200, Development of a real-time detection system for unidentified RCS leakage less than 0.5gpm, Choi Choon Gi
- Abstract
- Van der Waals (vdW) heterostructures (or heterojunctions) are formed by stacking two different 2D materials (e.g., graphene, h-BN, or transition metal dichalcogenides) across vdW gaps. In a type-II heterojunction, 2D semiconductors are aligned with staggered bandgaps, which can effectively separate electron and hole carriers, and enable promising high-performance photovoltaics and photodetectors. Herein, an effective vdW-homojunction is reported, formed by one 2D material (2H-WS2) with vdW gap engineering leading to different electronic structures and type-II junction formation. WS2 films are synthesized by W metal deposition and controlled sulfurization method leading to a nonuniform vdW gap strain in the film. The vdW strain gradients in multilayer WS2 films are confirmed by transmission electron microscopy analysis, and the modeling by density functional theory shows an effective type-II homojunction formation via modulated bandgaps by the vdW gap strains. The superior performance of a broadband photodetector application is confirmed by photoluminescence and photocurrent experiments.
- KSP Keywords
- 2D material, 2D semiconductors, Electronic structures, Hexagonal boron nitride(h-BN), High performance, Hole carriers, Strain gradient, Sulfurization method, Transmission Electron Microscopy(TEM), Type-II heterojunction, Van der Waals (vdW) heterostructures