Phase‐Dependent Band Gap Engineering in Alloys of Metal‐Semiconductor Transition Metal Dichalcogenides
[1];
- Department of Physics University of Illinois at Chicago Chicago IL 60607 USA
- Department of Physics Washington University in St. Louis St. Louis MO 63130 USA
- Department of Mechanical and Industrial Engineering University of Illinois at Chicago Chicago IL 60607 USA
- Department of Chemistry University of Illinois at Chicago Chicago IL 60607 USA
- Center for Nanoscale Materials Argonne National Laboratory Argonne IL 60439 USA
- Department of Mechanical Engineering and Material Science Washington University in St. Louis St. Louis MO 63130 USA, Institute of Materials Science and Engineering Washington University in St. Louis St. Louis MO 63130 USA
Abstract Bandgap engineering plays a critical role in optimizing the electrical, optical and (photo)‐electrochemical applications of semiconductors. Alloying has been a historically successful way of tuning bandgaps by making solid solutions of two isovalent semiconductors. In this work, a novel form of bandgap engineering involving alloying non‐isovalent cations in a 2D transition metal dichalcogenide (TMDC) is presented. By alloying semiconducting MoSe 2 with metallic NbSe 2 , two structural phases of Mo 0.5 Nb 0.5 Se 2 , the 1T and 2H phases, are produced each with emergent electronic structure. At room temperature, it is observed that the 1T and 2H phases are semiconducting and metallic, respectively. For the 1T structure, scanning tunneling microscopy/spectroscopy (STM/STS) is used to measure band gaps in the range of 0.42–0.58 at 77 K. Electron diffraction patterns of the 1T structure obtained at room temperature show the presence of a nearly commensurate charge density wave (NCCDW) phase with periodic lattice distortions that result in an uncommon 4 × 4 supercell, rotated approximately 4° from the lattice. Density‐functional‐theory calculations confirm that local distortions, such as those in a NCCDW, can open up a band gap in 1T ‐Mo 0.5 Nb 0.5 Se 2 , but not in the 2H phase. This work expands the boundaries of alloy‐based bandgap engineering by introducing a novel technique that facilitates CDW phases through alloying.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1785851
- Journal Information:
- Advanced Functional Materials, Journal Name: Advanced Functional Materials Vol. 30 Journal Issue: 51; ISSN 1616-301X
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- Germany
- Language:
- English
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