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Obaidulla SM, Supina A, Kamal S, Khan Y, Kralj M. van der Waals 2D transition metal dichalcogenide/organic hybridized heterostructures: recent breakthroughs and emerging prospects of the device. NANOSCALE HORIZONS 2023; 9:44-92. [PMID: 37902087 DOI: 10.1039/d3nh00310h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
The near-atomic thickness and organic molecular systems, including organic semiconductors and polymer-enabled hybrid heterostructures, of two-dimensional transition metal dichalcogenides (2D-TMDs) can modulate their optoelectronic and transport properties outstandingly. In this review, the current understanding and mechanism of the most recent and significant breakthrough of novel interlayer exciton emission and its modulation by harnessing the band energy alignment between TMDs and organic semiconductors in a TMD/organic (TMDO) hybrid heterostructure are demonstrated. The review encompasses up-to-date device demonstrations, including field-effect transistors, detectors, phototransistors, and photo-switchable superlattices. An exploration of distinct traits in 2D-TMDs and organic semiconductors delves into the applications of TMDO hybrid heterostructures. This review provides insights into the synthesis of 2D-TMDs and organic layers, covering fabrication techniques and challenges. Band bending and charge transfer via band energy alignment are explored from both structural and molecular orbital perspectives. The progress in emission modulation, including charge transfer, energy transfer, doping, defect healing, and phase engineering, is presented. The recent advancements in 2D-TMDO-based optoelectronic synaptic devices, including various 2D-TMDs and organic materials for neuromorphic applications are discussed. The section assesses their compatibility for synaptic devices, revisits the operating principles, and highlights the recent device demonstrations. Existing challenges and potential solutions are discussed. Finally, the review concludes by outlining the current challenges that span from synthesis intricacies to device applications, and by offering an outlook on the evolving field of emerging TMDO heterostructures.
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Affiliation(s)
- Sk Md Obaidulla
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička Cesta 46, HR-10000 Zagreb, Croatia.
- Department of Condensed Matter and Materials Physics, S. N. Bose National Centre for Basic Sciences, Sector III, Block JD, Salt Lake, Kolkata 700106, India
| | - Antonio Supina
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička Cesta 46, HR-10000 Zagreb, Croatia.
- Chair of Physics, Montanuniversität Leoben, Franz Josef Strasse 18, 8700 Leoben, Austria
| | - Sherif Kamal
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička Cesta 46, HR-10000 Zagreb, Croatia.
| | - Yahya Khan
- Department of Physics, Karakoram International university (KIU), Gilgit 15100, Pakistan
| | - Marko Kralj
- Center of Excellence for Advanced Materials and Sensing Devices, Institute of Physics, Bijenička Cesta 46, HR-10000 Zagreb, Croatia.
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Mahlouji R, Kessels WMME, Sagade AA, Bol AA. ALD-grown two-dimensional TiS x metal contacts for MoS 2 field-effect transistors. NANOSCALE ADVANCES 2023; 5:4718-4727. [PMID: 37705798 PMCID: PMC10496909 DOI: 10.1039/d3na00387f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/13/2023] [Indexed: 09/15/2023]
Abstract
Metal contacts to MoS2 field-effect transistors (FETs) play a determinant role in the device electrical characteristics and need to be chosen carefully. Because of the Schottky barrier (SB) and the Fermi level pinning (FLP) effects that occur at the contact/MoS2 interface, MoS2 FETs often suffer from high contact resistance (Rc). One way to overcome this issue is to replace the conventional 3D bulk metal contacts with 2D counterparts. Herein, we investigate 2D metallic TiSx (x ∼ 1.8) as top contacts for MoS2 FETs. We employ atomic layer deposition (ALD) for the synthesis of both the MoS2 channels as well as the TiSx contacts and assess the electrical performance of the fabricated devices. Various thicknesses of TiSx are grown on MoS2, and the resultant devices are electrically compared to the ones with the conventional Ti metal contacts. Our findings show that the replacement of 5 nm Ti bulk contacts with only ∼1.2 nm of 2D TiSx is beneficial in improving the overall device metrics. With such ultrathin TiSx contacts, the ON-state current (ION) triples and increases to ∼35 μA μm-1. Rc also reduces by a factor of four and reaches ∼5 MΩ μm. Such performance enhancements were observed despite the SB formed at the TiSx/MoS2 interface is believed to be higher than the SB formed at the Ti/MoS2 interface. These device metric improvements could therefore be mainly associated with an increased level of electrostatic doping in MoS2, as a result of using 2D TiSx for contacting the 2D MoS2. Our findings are also well supported by TCAD device simulations.
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Affiliation(s)
- Reyhaneh Mahlouji
- Department of Applied Physics, Eindhoven University of Technology P. O. Box 513 5600 MB Eindhoven The Netherlands
| | - Wilhelmus M M Erwin Kessels
- Department of Applied Physics, Eindhoven University of Technology P. O. Box 513 5600 MB Eindhoven The Netherlands
| | - Abhay A Sagade
- Department of Physics and Nanotechnology, Laboratory for Advanced Nanoelectronic Devices, SRM Institute of Science and Technology SRM Nagar, Kattankulathur 603 203 Tamil Nadu India
| | - Ageeth A Bol
- Department of Applied Physics, Eindhoven University of Technology P. O. Box 513 5600 MB Eindhoven The Netherlands
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Sunwoo H, Choi W. Tunable, stable, and reversible n-type doping of MoS 2via thermal treatment in N-methyl-2-pyrrolidone. NANOTECHNOLOGY 2022; 33:50LT01. [PMID: 36137437 DOI: 10.1088/1361-6528/ac9417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
Here, we report a highly stable and reversible n-type doping of monolayer MoS2using thermal treatment in N-methyl-2-pyrrolidone (NMP). The Raman and photoluminescence spectroscopic measurements as well as the device performance of the MoS2transistors suggested a stronger n-type doping effect with increasing time and temperature of the thermal treatment in NMP. Within the given time (5-60 min) and temperature (50 °C-110 °C), the surface treatment in NMP provided an electron concentration from 6 × 1010to 2 × 1012cm-2. Owing to the n-type doping effect, the thermal treatment in NMP reduced the contact resistance and enhanced the field-effect mobility of the MoS2transistors. The n-type doping via thermal treatment in NMP remained effective for more than 12 months in ambient air, and could be completely removed after immersion in isopropanol. These results demonstrate that thermal treatment in NMP can be a facile and effective route to achieve stable and reversible doping of two-dimensional materials including MoS2for their applications in high-performance electronics and optoelectronics.
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Affiliation(s)
- Hyeyeon Sunwoo
- School of Materials Science & Engineering, Kookmin University, Seoul 02707, Republic of Korea
| | - Woong Choi
- School of Materials Science & Engineering, Kookmin University, Seoul 02707, Republic of Korea
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Huang W, Zhang Y, Song M, Wang B, Hou H, Hu X, Chen X, Zhai T. Encapsulation strategies on 2D materials for field effect transistors and photodetectors. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.08.086] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Mahlouji R, Zhang Y, Verheijen MA, Hofmann JP, Kessels WMM, Sagade AA, Bol AA. On the Contact Optimization of ALD-Based MoS 2 FETs: Correlation of Processing Conditions and Interface Chemistry with Device Electrical Performance. ACS APPLIED ELECTRONIC MATERIALS 2021; 3:3185-3199. [PMID: 34337417 PMCID: PMC8320240 DOI: 10.1021/acsaelm.1c00379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
Despite the extensive ongoing research on MoS2 field effect transistors (FETs), the key role of device processing conditions in the chemistry involved at the metal-to-MoS2 interface and their influence on the electrical performance are often overlooked. In addition, the majority of reports on MoS2 contacts are based on exfoliated MoS2, whereas synthetic films are even more susceptible to the changes made in device processing conditions. In this paper, working FETs with atomic layer deposition (ALD)-based MoS2 films and Ti/Au contacts are demonstrated, using current-voltage (I-V) characterization. In pursuit of optimizing the contacts, high-vacuum thermal annealing as well as O2/Ar plasma cleaning treatments are introduced, and their influence on the electrical performance is studied. The electrical findings are linked to the interface chemistry through X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) analyses. XPS evaluation reveals that the concentration of organic residues on the MoS2 surface, as a result of resist usage during the device processing, is significant. Removal of these contaminations with O2/Ar plasma changes the MoS2 chemical state and enhances the MoS2 electrical properties. Based on the STEM analysis, the observed progress in the device electrical characteristics could also be associated with the formation of a continuous TiS x layer at the Ti-to-MoS2 interface. Scaling down the Ti interlayer thickness and replacing it with Cr is found to be beneficial as well, leading to further device performance advancements. Our findings are of value for attaining optimal contacts to synthetic MoS2 films.
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Affiliation(s)
- Reyhaneh Mahlouji
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Yue Zhang
- Laboratory
of Inorganic Materials and Catalysis, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Marcel A. Verheijen
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
- Eurofins
Materials Science, High
Tech Campus 11, Eindhoven 5656 AE, The Netherlands
| | - Jan P. Hofmann
- Laboratory
of Inorganic Materials and Catalysis, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
- Surface
Science Laboratory, Department of Materials and Earth Sciences, Technical University of Darmstadt, Otto-Berndt-Strasse 3, Darmstadt 64287, Germany
| | - Wilhelmus M. M. Kessels
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Abhay A. Sagade
- Laboratory
for Advanced Nanoelectronic Devices, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur 603 203, Tamil Nadu, India
| | - Ageeth A. Bol
- Department
of Applied Physics, Eindhoven University
of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
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Seo SG, Ryu JH, Kim SY, Jeong J, Jin SH. Enhancement of Photodetective Properties on Multilayered MoS 2 Thin Film Transistors via Self-Assembled Poly-L-Lysine Treatment and Their Potential Application in Optical Sensors. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:1586. [PMID: 34204218 PMCID: PMC8234691 DOI: 10.3390/nano11061586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/07/2021] [Accepted: 06/10/2021] [Indexed: 01/04/2023]
Abstract
Photodetectors and display backplane transistors based on molybdenum disulfide (MoS2) have been regarded as promising topics. However, most studies have focused on the improvement in the performances of the MoS2 photodetector itself or emerging applications. In this study, to suggest a better insight into the photodetector performances of MoS2 thin film transistors (TFTs), as photosensors for possible integrated system, we performed a comparative study on the photoresponse of MoS2 and hydrogenated amorphous silicon (a-Si:H) TFTs. As a result, in the various wavelengths and optical power ranges, MoS2 TFTs exhibit 2~4 orders larger photo responsivities and detectivities. The overall quantitative comparison of photoresponse in single device and inverters confirms a much better performance by the MoS2 photodetectors. Furthermore, as a strategy to improve the field effect mobility and photoresponse of the MoS2 TFTs, molecular doping via poly-L-lysine (PLL) treatment was applied to the MoS2 TFTs. Transfer and output characteristics of the MoS2 TFTs clearly show improved photocurrent generation under a wide range of illuminations (740~365 nm). These results provide useful insights for considering MoS2 as a next-generation photodetector in flat panel displays and makes it more attractive due to the fact of its potential as a high-performance photodetector enabled by a novel doping technique.
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Affiliation(s)
| | | | | | | | - Sung Hun Jin
- Department of Electronic Engineering, Incheon National University, Incheon 22012, Korea; (S.G.S.); (J.H.R.); (S.Y.K.); (J.J.)
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Yoo H, Heo K, Ansari MHR, Cho S. Recent Advances in Electrical Doping of 2D Semiconductor Materials: Methods, Analyses, and Applications. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:832. [PMID: 33805062 PMCID: PMC8064109 DOI: 10.3390/nano11040832] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 03/19/2021] [Accepted: 03/22/2021] [Indexed: 12/22/2022]
Abstract
Two-dimensional materials have garnered interest from the perspectives of physics, materials, and applied electronics owing to their outstanding physical and chemical properties. Advances in exfoliation and synthesis technologies have enabled preparation and electrical characterization of various atomically thin films of semiconductor transition metal dichalcogenides (TMDs). Their two-dimensional structures and electromagnetic spectra coupled to bandgaps in the visible region indicate their suitability for digital electronics and optoelectronics. To further expand the potential applications of these two-dimensional semiconductor materials, technologies capable of precisely controlling the electrical properties of the material are essential. Doping has been traditionally used to effectively change the electrical and electronic properties of materials through relatively simple processes. To change the electrical properties, substances that can donate or remove electrons are added. Doping of atomically thin two-dimensional semiconductor materials is similar to that used for silicon but has a slightly different mechanism. Three main methods with different characteristics and slightly different principles are generally used. This review presents an overview of various advanced doping techniques based on the substitutional, chemical, and charge transfer molecular doping strategies of graphene and TMDs, which are the representative 2D semiconductor materials.
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Affiliation(s)
- Hocheon Yoo
- Department of Electronic Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 13120, Korea; (H.Y.); (M.H.R.A.)
- Graduate School of IT Convergence Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 13120, Korea
| | - Keun Heo
- Department of Semiconductor Science & Technology, Jeonbuk National University, Jeonju-si, Jeollabuk-do 54896, Korea;
| | - Md. Hasan Raza Ansari
- Department of Electronic Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 13120, Korea; (H.Y.); (M.H.R.A.)
- Graduate School of IT Convergence Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 13120, Korea
| | - Seongjae Cho
- Department of Electronic Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 13120, Korea; (H.Y.); (M.H.R.A.)
- Graduate School of IT Convergence Engineering, Gachon University, 1342 Seongnamdaero, Sujeong-gu, Seongnam-si, Gyeonggi-do 13120, Korea
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Nalwa HS. A review of molybdenum disulfide (MoS 2) based photodetectors: from ultra-broadband, self-powered to flexible devices. RSC Adv 2020; 10:30529-30602. [PMID: 35516069 PMCID: PMC9056353 DOI: 10.1039/d0ra03183f] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 07/17/2020] [Indexed: 12/23/2022] Open
Abstract
Two-dimensional transition metal dichalcogenides (2D TMDs) have attracted much attention in the field of optoelectronics due to their tunable bandgaps, strong interaction with light and tremendous capability for developing diverse van der Waals heterostructures (vdWHs) with other materials. Molybdenum disulfide (MoS2) atomic layers which exhibit high carrier mobility and optical transparency are very suitable for developing ultra-broadband photodetectors to be used from surveillance and healthcare to optical communication. This review provides a brief introduction to TMD-based photodetectors, exclusively focused on MoS2-based photodetectors. The current research advances show that the photoresponse of atomic layered MoS2 can be significantly improved by boosting its charge carrier mobility and incident light absorption via forming MoS2 based plasmonic nanostructures, halide perovskites-MoS2 heterostructures, 2D-0D MoS2/quantum dots (QDs) and 2D-2D MoS2 hybrid vdWHs, chemical doping, and surface functionalization of MoS2 atomic layers. By utilizing these different integration strategies, MoS2 hybrid heterostructure-based photodetectors exhibited remarkably high photoresponsivity raging from mA W-1 up to 1010 A W-1, detectivity from 107 to 1015 Jones and a photoresponse time from seconds (s) to nanoseconds (10-9 s), varying by several orders of magnitude from deep-ultraviolet (DUV) to the long-wavelength infrared (LWIR) region. The flexible photodetectors developed from MoS2-based hybrid heterostructures with graphene, carbon nanotubes (CNTs), TMDs, and ZnO are also discussed. In addition, strain-induced and self-powered MoS2 based photodetectors have also been summarized. The factors affecting the figure of merit of a very wide range of MoS2-based photodetectors have been analyzed in terms of their photoresponsivity, detectivity, response speed, and quantum efficiency along with their measurement wavelengths and incident laser power densities. Conclusions and the future direction are also outlined on the development of MoS2 and other 2D TMD-based photodetectors.
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Affiliation(s)
- Hari Singh Nalwa
- Advanced Technology Research 26650 The Old Road Valencia California 91381 USA
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Cho K, Pak J, Chung S, Lee T. Recent Advances in Interface Engineering of Transition-Metal Dichalcogenides with Organic Molecules and Polymers. ACS NANO 2019; 13:9713-9734. [PMID: 31330111 DOI: 10.1021/acsnano.9b02540] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The interface engineering of two-dimensional (2D) transition-metal dichalcogenides (TMDs) has been regarded as a promising strategy to modulate their outstanding electrical and optoelectronic properties because of their inherent 2D nature and large surface-to-volume ratio. In particular, introducing organic molecules and polymers directly onto the surface of TMDs has been explored to passivate the surface defects or achieve better interfacial properties with neighboring surfaces efficiently, thus leading to great opportunities for the realization of high-performance TMD-based applications. This review provides recent progress in the interface engineering of TMDs with organic molecules and polymers corresponding to the modulation of their electrical and optoelectronic characteristics. Depending on the interfaces between the surface of TMDs and dielectric, conductive contacts or the ambient environment, we present various strategies to introduce an organic interlayer from materials to processing. In addition, the role of native defects on the surface of TMDs, such as adatoms or vacancies, in determining their electrical characteristics is also discussed in detail. Finally, the future challenges and opportunities associated with the interface engineering are highlighted.
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Affiliation(s)
- Kyungjune Cho
- Department of Physics and Astronomy and Institute of Applied Physics , Seoul National University , Seoul 08826 , Korea
| | - Jinsu Pak
- Department of Physics and Astronomy and Institute of Applied Physics , Seoul National University , Seoul 08826 , Korea
| | - Seungjun Chung
- Photo-electronic Hybrids Research Center , Korea Institute of Science and Technology (KIST) , Seoul 02792 , Korea
| | - Takhee Lee
- Department of Physics and Astronomy and Institute of Applied Physics , Seoul National University , Seoul 08826 , Korea
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Kim SH, Han KH, Park E, Kim SG, Yu HY. Ultralow Schottky Barrier Height Achieved by Using Molybdenum Disulfide/Dielectric Stack for Source/Drain Contact. ACS APPLIED MATERIALS & INTERFACES 2019; 11:34084-34090. [PMID: 31429263 DOI: 10.1021/acsami.9b10746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Energy barrier formed at a metal/semiconductor interface is a critical factor determining the performance of nanoelectronic devices. Although diverse methods for reducing the Schottky barrier height (SBH) via interface engineering have been developed, it is still difficult to achieve both an ultralow SBH and a low dependence on the contact metals. In this study, a novel structure, namely, a metal/transition-metal dichalcogenide (TMD) interlayer (IL)/dielectric IL/semiconductor (MTDS) structure, was developed to overcome these issues. Molybdenum disulfide (MoS2) is a promising TMD IL material owing to its interface characteristics, which yields a low SBH and reduces the reliance on contact metals. Moreover, an ultralow SBH is achieved via the insertion of an ultrathin ZnO layer between MoS2 and a semiconductor, thereby inducing an n-type doping effect on the MoS2 IL and forming an interface dipole in the favorable direction at the ZnO IL/semiconductor interfaces. Consequently, the lowest SBH (0.07 eV) and a remarkable improvement in the reverse current density (by a factor of approximately 5400) are achieved, with a wide room for contact-metal dependence. This study experimentally and theoretically validates the effect of the proposed MTDS structure, which can be a key technique for next-generation nanoelectronics.
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