Strong Band Bowing Effects and Distinctive Optoelectronic Properties of 2H and 1T′ Phase‐Tunable MoxRe1–xS2 Alloys

• Published in: Advanced functional materials 2020-08, Vol.30 (34), p.n/a
• Main Authors: Deng, Qixin, Li, Xiaobo, Si, Huayan, Hong, Jinhua, Wang, Shiyao, Feng, Qingliang, Hu, Chen‐Xia, Wang, Shanshan, Zhang, Hao‐Li, Suenaga, Kazu, Xu, Hua
• Format: Article
• Language: English
• Subjects: 2D alloy; Alloying effects; Bowing; Chemical vapor deposition; Composition; Crystal structure; Doping; Electron states; Electronic devices; energy band engineering; Energy bands; Materials science; Materials selection; MoS2; Optoelectronic devices; Phase modulation; Phase separation; Photoelectrons; ReS2; Solid phases; Synthesis; Two dimensional materials
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202003264

Structure and energy band engineering of 2D materials via selective doping or phase modulation provide a significant opportunity to design them for optoelectronic devices. Here, the synthesis of high‐quality MoxRe1–xS2 alloys with tunable composition and phase structure via chemical vapor deposition growth is reported, and their novel energy band structures and optoelectronic properties are explored. The phase separation and structure reconstruction, which are found to be two serious problems in the synthesis of these alloys, are successfully suppressed through tuning their growth thermodynamics. As a result, the obtained MoxRe1–xS2 alloys have uniform composition, phase structure, and crystal orientation. Together with X‐ray photoelectron spectroscopy analysis and first‐principle calculation, the Re/Mo doping‐induced Fermi level up‐shift/down‐shift, new electronic states, and “sub‐gap” formation in MoxRe1–xS2 alloys are revealed. Especially, a strong band bowing effect is discovered in the MoxRe1–xS2 alloys with structure transition between 1T′ and 2H phases. Furthermore, these alloys reveal tunable conduction behavior from n‐type to bipolar and p‐type in 1T′ phase, as well as novel “bipolar‐like” electron conduction behavior in 2H alloys. The results highlight the unique alloying effects, which do not exist in the single‐phase 2D alloys, and provide the feasibility for potential applications in building novel electronic and optoelectronic devices. Phase‐tunable MoxRe1–xS2 alloys with uniform composition and phase structure are synthesized via chemical vapor deposition growth. The strong band bowing effects and distinctive optoelectronic properties are revealed in these alloys, which open up new prospects for transition metal dichalcogenides in building multifunctional electronic and optoelectronic devices.