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Li J, Yuan Y, Lanza M, Abate I, Tian B, Zhang X. Nonepitaxial Wafer-Scale Single-Crystal 2D Materials on Insulators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2310921. [PMID: 38118051 DOI: 10.1002/adma.202310921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/01/2023] [Indexed: 12/22/2023]
Abstract
Next-generation nanodevices require 2D material synthesis on insulating substrates. However, growing high-quality 2D-layered materials, such as hexagonal boron nitride (hBN) and graphene, on insulators is challenging owing to the lack of suitable metal catalysts, imperfect lattice matching with substrates, and other factors. Therefore, developing a generally applicable approach for realizing high-quality 2D layers on insulators remains crucial, despite numerous strategies being explored. Herein, a universal strategy is introduced for the nonepitaxial synthesis of wafer-scale single-crystal 2D materials on arbitrary insulating substrates. The metal foil in a nonadhered metal-insulator substrate system is almost melted by a brief high-temperature treatment, thereby pressing the as-grown 2D layers to well attach onto the insulators. High-quality, large-area, single-crystal, monolayer hBN and graphene films are synthesized on various insulating substrates. This strategy provides new pathways for synthesizing various 2D materials on arbitrary insulators and offers a universal epitaxial platform for future single-crystal film production.
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Affiliation(s)
- Junzhu Li
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Yue Yuan
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Mario Lanza
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Iwnetim Abate
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Chemistry, University of California, Berkeley, CA, 97420, USA
- Department of Materials Science & Engineering, University of California, Berkeley, CA, 97420, USA
| | - Bo Tian
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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Ali A, Shin YH. Strain and thickness effects on the electronic structures of low-energy two-dimensional Cd xTe y phases. Phys Chem Chem Phys 2022; 24:29772-29780. [PMID: 36458904 DOI: 10.1039/d2cp04123e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cadmium telluride (CdTe) has prime importance in photovoltaics due to its direct band gap of 1.45 eV. However, its two-dimensional counterparts have not been fully explored due to polymorphism. We investigated the energy phase diagram of 2D CdxTey (x + y ≤ 8) using state-of-art computational methods and found the phases of CdTe and CdTe2 on and near the energy convex-hull, respectively. Further screening of phonon and ab initio molecular dynamics simulations confirms their experimental viability. These structures reveal promising electronic properties. 2D CdTe has a robust direct band gap unaffected by thickness, monolayer to trilayer and bulk, and strain as high as ±7%. Such robust semiconductors are crucial for device applications because of challenges in the growth of wafer-scale uniform monolayers. In contrast, the direct band gap of 2D transition metal dichalcogenides is highly sensitive to thickness and strain, limiting their usage in devices. The 2D CdTe2 has an indirect band gap whose magnitude is tunable by strain. The robust direct band gap of 2D CdTe and the tunable indirect band gap of CdTe2 make them potential candidates for optoelectronic devices.
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Affiliation(s)
- Asad Ali
- Multiscale Materials Modeling Laboratory, Department of Physics, University of Ulsan, Ulsan 44610, Republic of Korea.
| | - Young-Han Shin
- Multiscale Materials Modeling Laboratory, Department of Physics, University of Ulsan, Ulsan 44610, Republic of Korea.
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Li J, Samad A, Schwingenschlögl U, Tian B, Lanza M, Zhang X. Morphology-Control Growth of Graphene Islands by Nonlinear Carbon Supply. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2206080. [PMID: 36052575 DOI: 10.1002/adma.202206080] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/18/2022] [Indexed: 06/15/2023]
Abstract
Controlling the morphology of graphene and other 2D materials in chemical vapor deposition (CVD) growth is crucial because the morphology reflects the crystal quality of as-synthesized nanomaterials in a certain way, and consequently it indirectly represents the physical properties of 2D materials such as bandgap, selective ion transportation, and impermeability. However, precise control of the morphology is limited by the complex formation mechanism and sensitive growth-environment factors of graphene. Therefore, the CVD synthesis of single-crystal hexagonal-shaped graphene islands with specific sizes is challenging. Herein, an unconventional nonlinear-carbon-supply growth strategy is proposed to realize controllable CVD growth of desired hexagonal graphene islands with specific sizes on Cu substrates. Large-area graphene films of isolated islands with desired densities, sizes, and distances between the islands are successfully synthesized. Subsequently, the direct growth of a planar-tunnel-junction structure based on two parallel gapped graphene islands is achieved by specific adjustment of the growth and etching processes of graphene CVD synthesis. It is therefore demonstrated that the nonlinear-carbon-supply growth strategy is a reliable method for the synthesis of high-quality graphene and can facilitate the direct growth of graphene-based nanodevices in the future.
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Affiliation(s)
- Junzhu Li
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
- Eleven-Dimensional Nanomaterial Research Institute, Xiamen, 361000, China
| | - Abdus Samad
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Udo Schwingenschlögl
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Bo Tian
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
- Eleven-Dimensional Nanomaterial Research Institute, Xiamen, 361000, China
| | - Mario Lanza
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Xixiang Zhang
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
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