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Huang Y, Li M, Hu Z, Hu C, Shen W, Li Y, Sun L. In Situ Studies on the Influence of Surface Symmetry on the Growth of MoSe 2 Monolayer on Sapphire Using Reflectance Anisotropy Spectroscopy and Differential Reflectance Spectroscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1457. [PMID: 39269119 PMCID: PMC11397682 DOI: 10.3390/nano14171457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2024] [Revised: 08/23/2024] [Accepted: 09/05/2024] [Indexed: 09/15/2024]
Abstract
The surface symmetry of the substrate plays an important role in the epitaxial high-quality growth of 2D materials; however, in-depth and in situ studies on these materials during growth are still limited due to the lack of effective in situ monitoring approaches. In this work, taking the growth of MoSe2 as an example, the distinct growth processes on Al2O3 (112¯0) and Al2O3 (0001) are revealed by parallel monitoring using in situ reflectance anisotropy spectroscopy (RAS) and differential reflectance spectroscopy (DRS), respectively, highlighting the dominant role of the surface symmetry. In our previous study, we found that the RAS signal of MoSe2 grown on Al2O3 (112¯0) initially increased and decreased ultimately to the magnitude of bare Al2O3 (112¯0) when the first layer of MoSe2 was fully merged, which is herein verified by the complementary DRS measurement that is directly related to the film coverage. Consequently, the changing rate of reflectance anisotropy (RA) intensity at 2.5 eV is well matched with the dynamic changes in differential reflectance (DR) intensity. Moreover, the surface-dominated uniform orientation of MoSe2 islands at various stages determined by RAS was further investigated by low-energy electron diffraction (LEED) and atomic force microscopy (AFM). By contrast, the RAS signal of MoSe2 grown on Al2O3 (0001) remains at zero during the whole growth, implying that the discontinuous MoSe2 islands have no preferential orientations. This work demonstrates that the combination of in situ RAS and DRS can provide valuable insights into the growth of unidirectional aligned islands and help optimize the fabrication process for single-crystal transition metal dichalcogenide (TMDC) monolayers.
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Affiliation(s)
- Yufeng Huang
- State Key Laboratory of Precision Measurement Technology and Instruments, School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Mengjiao Li
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, Center for Joint Quantum Studies, Tianjin University, Tianjin 300350, China
| | - Zhixin Hu
- Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Department of Physics, Center for Joint Quantum Studies, Tianjin University, Tianjin 300350, China
| | - Chunguang Hu
- State Key Laboratory of Precision Measurement Technology and Instruments, School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Wanfu Shen
- State Key Laboratory of Precision Measurement Technology and Instruments, School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Yanning Li
- State Key Laboratory of Precision Measurement Technology and Instruments, School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Lidong Sun
- Institute of Experimental Physics, Johannes Kepler University Linz, A-4040 Linz, Austria
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Ludwiczak K, Da̧browska AK, Binder J, Tokarczyk M, Iwański J, Kurowska B, Turczyński J, Kowalski G, Bożek R, Stȩpniewski R, Pacuski W, Wysmołek A. Heteroepitaxial Growth of High Optical Quality, Wafer-Scale van der Waals Heterostrucutres. ACS APPLIED MATERIALS & INTERFACES 2021; 13:47904-47911. [PMID: 34606228 PMCID: PMC8517960 DOI: 10.1021/acsami.1c11867] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/16/2021] [Indexed: 05/05/2023]
Abstract
Transition metal dichalcogenides (TMDs) are materials that can exhibit intriguing optical properties like a change of the bandgap from indirect to direct when being thinned down to a monolayer. Well-resolved narrow excitonic resonances can be observed for such monolayers although only for materials of sufficient crystalline quality and so far mostly available in the form of micrometer-sized flakes. A further significant improvement of optical and electrical properties can be achieved by transferring the TMD on hexagonal boron nitride (hBN). To exploit the full potential of TMDs in future applications, epitaxial techniques have to be developed that not only allow the growth of large-scale, high-quality TMD monolayers but also allow the growth to be performed directly on large-scale epitaxial hBN. In this work, we address this problem and demonstrate that MoSe2 of high optical quality can be directly grown on epitaxial hBN on an entire 2 in. wafer. We developed a combined growth theme for which hBN is first synthesized at high temperature by metal organic vapor phase epitaxy (MOVPE) and as a second step MoSe2 is deposited on top by molecular beam epitaxy (MBE) at much lower temperatures. We show that this structure exhibits excellent optical properties, manifested by narrow excitonic lines in the photoluminescence spectra. Moreover, the material is homogeneous on the area of the whole 2 in. wafer with only ±0.14 meV deviation of excitonic energy. Our mixed growth technique may guide the way for future large-scale production of high quality TMD/hBN heterostructures.
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Affiliation(s)
- Katarzyna Ludwiczak
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | | | - Johannes Binder
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Mateusz Tokarczyk
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Jakub Iwański
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Bogusława Kurowska
- Institute
of Physics Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Jakub Turczyński
- Institute
of Physics Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Grzegorz Kowalski
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Rafał Bożek
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Roman Stȩpniewski
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Wojciech Pacuski
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Andrzej Wysmołek
- Faculty
of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
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An In Situ Reflectance Spectroscopic Investigation to Monitor Two-Dimensional MoS 2 Flakes on a Sapphire Substrate. MATERIALS 2020; 13:ma13245794. [PMID: 33353072 PMCID: PMC7766002 DOI: 10.3390/ma13245794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 11/25/2022]
Abstract
In this work, we demonstrate the application of differential reflectance spectroscopy (DRS) to monitor the growth of molybdenum disulfide (MoS2) using chemical vapor deposition (CVD). The growth process, optical properties, and structure evolution of MoS2 were recorded by in-situ DRS. Indeed, blue shifts of the characteristic peak B were discussed with the decrease of temperature. We also obtained the imaginary part of the MoS2 dielectric constant according to reflectance spectra. This method provides an approach for studying the change of two-dimensional (2D) materials’ dielectric constant with temperature. More importantly, our work emphasizes that the DRS technique is a non-destructive and effective method for in-situ monitoring the growth of 2D materials, which is helpful in guiding the preparation of 2D materials.
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