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Gao J, Xie W, Luo X, Qin Y, Zhao Z. Anisotropic Effects in Local Anodic Oxidation Nanolithography on Silicon Surfaces: Insights from ReaxFF Molecular Dynamics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40. [PMID: 39008811 PMCID: PMC11295202 DOI: 10.1021/acs.langmuir.4c01129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/27/2024] [Accepted: 07/02/2024] [Indexed: 07/17/2024]
Abstract
Fully understanding the anisotropic effect of silicon surface orientations in local anodic oxidation (LAO) nanolithography processes is critical to the precise control of oxide quality and rate. This study used ReaxFF MD simulations to reveal the surface anisotropic effects in the LAO through the analysis of adsorbed species, atomic charge, and oxide growth. Our results show that the LAO behaves differently on silicon (100), (110), and (111) surfaces. Specifically, the application of an electric field significantly increases the quantity of surface-adsorbed -OH2 while reducing -OH on the (111) surface, and results in a higher charge on a greater number of Si atoms on the (100) surface. Moreover, the quantity of surface-adsorbed -OH plays a pivotal role in influencing the oxidation rate, as it directly correlates with an increased formation rate of Si-O-Si bonds. During bias-induced oxidation, the (111) surface appears with a high initial oxidation rate among three surfaces, while the (110) surface underwent increased oxidation at higher electric field strengths. This conclusion is based on the analysis of the evolution of Si-O-Si bond number, surface elevation, and oxide thickness. Our findings align well with prior theoretical and experimental studies, providing deeper insights and clear guidance for the fabrication of high-performance nanoinsulator gates using LAO nanolithography.
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Affiliation(s)
- Jian Gao
- Centre for Precision Manufacturing,
Department of Design, Manufacturing and Engineering Management, University of Strathclyde, Glasgow G1 1XJ, U.K.
| | - Wenkun Xie
- Centre for Precision Manufacturing,
Department of Design, Manufacturing and Engineering Management, University of Strathclyde, Glasgow G1 1XJ, U.K.
| | - Xichun Luo
- Centre for Precision Manufacturing,
Department of Design, Manufacturing and Engineering Management, University of Strathclyde, Glasgow G1 1XJ, U.K.
| | - Yi Qin
- Centre for Precision Manufacturing,
Department of Design, Manufacturing and Engineering Management, University of Strathclyde, Glasgow G1 1XJ, U.K.
| | - Zhiyong Zhao
- Centre for Precision Manufacturing,
Department of Design, Manufacturing and Engineering Management, University of Strathclyde, Glasgow G1 1XJ, U.K.
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2
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Strobel C, Chavarin CA, Knaut M, Albert M, Heinzig A, Gummadi L, Wenger C, Mikolajick T. p-Type Schottky Contacts for Graphene Adjustable-Barrier Phototransistors. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1140. [PMID: 38998745 PMCID: PMC11243045 DOI: 10.3390/nano14131140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 06/21/2024] [Accepted: 06/22/2024] [Indexed: 07/14/2024]
Abstract
The graphene adjustable-barriers phototransistor is an attractive novel device for potential high speed and high responsivity dual-band photodetection. In this device, graphene is embedded between the semiconductors silicon and germanium. Both n-type and p-type Schottky contacts between graphene and the semiconductors are required for this device. While n-type Schottky contacts are widely investigated, reports about p-type Schottky contacts between graphene and the two involved semiconductors are scarce. In this study, we demonstrate a p-type Schottky contact between graphene and p-germanium. A clear rectification with on-off ratios of close to 103 (±5 V) and a distinct photoresponse at telecommunication wavelengths in the infrared are achieved. Further, p-type silicon is transferred to or deposited on graphene, and we also observe rectification and photoresponse in the visible range for some of these p-type Schottky junctions. These results are an important step toward the realization of functional graphene adjustable-barrier phototransistors.
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Affiliation(s)
- Carsten Strobel
- Institute of Semiconductors and Microsystems, Chair of Nanoelectronics, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany; (M.K.); (M.A.); (A.H.); (L.G.); (T.M.)
| | - Carlos Alvarado Chavarin
- IHP—Leibniz-Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany; (C.A.C.); (C.W.)
| | - Martin Knaut
- Institute of Semiconductors and Microsystems, Chair of Nanoelectronics, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany; (M.K.); (M.A.); (A.H.); (L.G.); (T.M.)
| | - Matthias Albert
- Institute of Semiconductors and Microsystems, Chair of Nanoelectronics, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany; (M.K.); (M.A.); (A.H.); (L.G.); (T.M.)
| | - André Heinzig
- Institute of Semiconductors and Microsystems, Chair of Nanoelectronics, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany; (M.K.); (M.A.); (A.H.); (L.G.); (T.M.)
| | - Likhith Gummadi
- Institute of Semiconductors and Microsystems, Chair of Nanoelectronics, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany; (M.K.); (M.A.); (A.H.); (L.G.); (T.M.)
| | - Christian Wenger
- IHP—Leibniz-Institut für Innovative Mikroelektronik, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany; (C.A.C.); (C.W.)
- Semiconductor Materials, Brandenburg University of Technology Cottbus-Senftenberg, Platz der Deutschen Einheit 1, 03046 Cottbus, Germany
| | - Thomas Mikolajick
- Institute of Semiconductors and Microsystems, Chair of Nanoelectronics, Technische Universität Dresden, Nöthnitzer Straße 64, 01187 Dresden, Germany; (M.K.); (M.A.); (A.H.); (L.G.); (T.M.)
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Sharaf Aldeen EM, Jalil AA, Mim RS, Hatta AH, Hazril NIH, Chowdhury A, Hassan NS, Rajendran S. Environmental remediation of hazardous pollutants using MXene-perovskite-based photocatalysts: A review. ENVIRONMENTAL RESEARCH 2023; 234:116576. [PMID: 37423362 DOI: 10.1016/j.envres.2023.116576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/19/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
Photocatalysis utilizing semiconductors offer a cost-effective and promising solution for the removal of pollutants. MXene and perovskites, which possess desirable properties such as a suitable bandgap, stability, and affordability, have emerged as a highly promising material for photocatalytic activity. However, the efficiency of MXene and perovskites is limited by their fast recombination rates and inadequate light harvesting abilities. Nonetheless, several additional modifications have been shown to enhance their performance, thereby warranting further exploration. This study delves into the fundamental principles of reactive species for MXene-perovskites. Various methods of modification of MXene-perovskite-based photocatalysts, including Schottky junction, Z-scheme and S-scheme are analyzed with regard to their operation, differences, identification techniques and reusability. The assemblance of heterojunctions is demonstrated to enhance photocatalytic activity while also suppressing charge carrier recombination. Furthermore, the separation of photocatalysts through magnetic-based methods is also investigated. Consequently, MXene-perovskite-based photocatalysts are seen as an exciting emerging technology that necessitates further research and development.
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Affiliation(s)
- E M Sharaf Aldeen
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor, Malaysia
| | - A A Jalil
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor, Malaysia; Centre of Hydrogen Energy, Institute of Future Energy, 81310, UTM Johor Bahru, Johor, Malaysia.
| | - R S Mim
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor, Malaysia
| | - A H Hatta
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor, Malaysia
| | - N I H Hazril
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor, Malaysia
| | - A Chowdhury
- Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310, UTM Johor Bahru, Johor, Malaysia
| | - N S Hassan
- Centre of Hydrogen Energy, Institute of Future Energy, 81310, UTM Johor Bahru, Johor, Malaysia
| | - S Rajendran
- Faculty of Engineering, Department of Mechanical Engineering, University of Tarapacá, Avda, General Velasquez, 1775, Arica, Chile
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Mendoza CD, Freire FL. Single-Layer Graphene/Germanium Interface Representing a Schottky Junction Studied by Photoelectron Spectroscopy. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2166. [PMID: 37570483 PMCID: PMC10420948 DOI: 10.3390/nano13152166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023]
Abstract
We investigated the interfacial electronic structure of the bidimensional interface of single-layer graphene on a germanium substrate. The procedure followed a well-established approach using ultraviolet (UPS) and X-ray (XPS) photoelectron spectroscopy. The direct synthesis of the single-layer graphene on the surface of (110) undoped Ge substrates was conducted via chemical vapor deposition (CVD). The main graphitic properties of the systems were identified, and it was shown that the Ge substrate affected the electronic structure of the single-layer graphene, indicating the electronic coupling between the graphene and the Ge substrate. Furthermore, the relevant features associated with the Schottky contact's nature, the energy level's alignments, and the energy barrier's heights for electron and hole injection were obtained in this work. The results are useful, given the possible integration of single-layer graphene on a Ge substrate with the complementary metal-oxide-semiconductor (CMOS) technology.
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Affiliation(s)
- Cesar D. Mendoza
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro 22451-900, RJ, Brazil;
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Galbiati M, Persichetti L, Gori P, Pulci O, Bianchi M, Di Gaspare L, Tersoff J, Coletti C, Hofmann P, De Seta M, Camilli L. Tuning the Doping of Epitaxial Graphene on a Conventional Semiconductor via Substrate Surface Reconstruction. J Phys Chem Lett 2021; 12:1262-1267. [PMID: 33497236 DOI: 10.1021/acs.jpclett.0c03649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Combining scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we demonstrate how to tune the doping of epitaxial graphene from p to n by exploiting the structural changes that occur spontaneously on the Ge surface upon thermal annealing. Furthermore, using first-principle calculations, we build a model that successfully reproduces the experimental observations. Since the ability to modify graphene electronic properties is of fundamental importance when it comes to applications, our results provide an important contribution toward the integration of graphene with conventional semiconductors.
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Affiliation(s)
- Miriam Galbiati
- Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | | | - Paola Gori
- Department of Engineering, Roma Tre University, 00146 Rome, Italy
| | - Olivia Pulci
- Department of Physics, University of Rome "Tor Vergata", 00133 Rome, Italy
- Istituto Nazionale di Fisica Nucleare, Roma 2, 00133 Rome, Italy
| | - Marco Bianchi
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | | | - Jerry Tersoff
- IBM Research Division, T.J. Watson Research Center, Yorktown Heights, New York, New York 10598, United States
| | - Camilla Coletti
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa 56127, Italy
- Graphene Laboratories, Istituto Italiano di Tecnologia, Genova 16163, Italy
| | - Philip Hofmann
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Monica De Seta
- Department of Sciences, Roma Tre University, 00146 Rome, Italy
| | - Luca Camilli
- Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
- Department of Physics, University of Rome "Tor Vergata", 00133 Rome, Italy
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Camphor-Based CVD Bilayer Graphene/Si Heterostructures for Self-Powered and Broadband Photodetection. MICROMACHINES 2020; 11:mi11090812. [PMID: 32867054 PMCID: PMC7570377 DOI: 10.3390/mi11090812] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 11/21/2022]
Abstract
This work demonstrates a self-powered and broadband photodetector using a heterojunction formed by camphor-based chemical vaper deposition (CVD) bilayer graphene on p-Si substrates. Here, graphene/p-Si heterostructures and graphene layers serve as ultra-shallow junctions for UV absorption and zero bandgap junction materials (<Si bandgap (1.1 eV)) for long-wave near-infrared (LWNIR) absorption, respectively. According to the Raman spectra and large-area (16 × 16 μm2) Raman mapping, a low-defect, >95% coverage bilayer and high-uniformity graphene were successfully obtained by camphor-based CVD processes. Furthermore, the carrier mobility of the camphor-based CVD bilayer graphene at room temperature is 1.8 × 103 cm2/V·s. Due to the incorporation of camphor-based CVD graphene, the graphene/p-Si Schottky junctions show a good rectification property (rectification ratio of ~110 at ± 2 V) and good performance as a self-powered (under zero bias) photodetector from UV to LWNIR. The photocurrent to dark current ratio (PDCR) value is up to 230 at 0 V under white light illumination, and the detectivity (D*) is 8 × 1012 cmHz1/2/W at 560 nm. Furthermore, the photodetector (PD) response/decay time (i.e., rise/fall time) is ~118/120 μs. These results support the camphor-based CVD bilayer graphene/Si Schottky PDs for use in self-powered and ultra-broadband light detection in the future.
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Bekdüz B, Kaya U, Langer M, Mertin W, Bacher G. Direct growth of graphene on Ge(100) and Ge(110) via thermal and plasma enhanced CVD. Sci Rep 2020; 10:12938. [PMID: 32737382 PMCID: PMC7395096 DOI: 10.1038/s41598-020-69846-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 07/14/2020] [Indexed: 11/12/2022] Open
Abstract
The integration of graphene into CMOS compatible Ge technology is in particular attractive for optoelectronic devices in the infrared spectral range. Since graphene transfer from metal substrates has detrimental effects on the electrical properties of the graphene film and moreover, leads to severe contamination issues, direct growth of graphene on Ge is highly desirable. In this work, we present recipes for a direct growth of graphene on Ge via thermal chemical vapor deposition (TCVD) and plasma-enhanced chemical vapor deposition (PECVD). We demonstrate that the growth temperature can be reduced by about 200 °C in PECVD with respect to TCVD, where usually growth occurs close to the melting point of Ge. For both, TCVD and PECVD, hexagonal and elongated morphology is observed on Ge(100) and Ge(110), respectively, indicating the dominant role of substrate orientation on the shape of graphene grains. Interestingly, Raman data indicate a compressive strain of ca. − 0.4% of the graphene film fabricated by TCVD, whereas a tensile strain of up to + 1.2% is determined for graphene synthesized via PECVD, regardless the substrate orientation. Supported by Kelvin probe force measurements, we suggest a mechanism that is responsible for graphene formation on Ge and the resulting strain in TCVD and PECVD.
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Affiliation(s)
- Bilge Bekdüz
- Werkstoffe der Elektrotechnik and CENIDE, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Umut Kaya
- Werkstoffe der Elektrotechnik and CENIDE, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Moritz Langer
- Werkstoffe der Elektrotechnik and CENIDE, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Wolfgang Mertin
- Werkstoffe der Elektrotechnik and CENIDE, Universität Duisburg-Essen, 47057, Duisburg, Germany.
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, Universität Duisburg-Essen, 47057, Duisburg, Germany
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