1
|
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.
Collapse
Affiliation(s)
- Cesar D. Mendoza
- Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, Rio de Janeiro 22451-900, RJ, Brazil;
| | | |
Collapse
|
2
|
Aprojanz J, Rosenzweig P, Nguyen TTN, Karakachian H, Küster K, Starke U, Lukosius M, Lippert G, Sinterhauf A, Wenderoth M, Zakharov AA, Tegenkamp C. High-Mobility Epitaxial Graphene on Ge/Si(100) Substrates. ACS APPLIED MATERIALS & INTERFACES 2020; 12:43065-43072. [PMID: 32865383 DOI: 10.1021/acsami.0c10725] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Graphene was shown to reveal intriguing properties of its relativistic two-dimensional electron gas; however, its implementation to microelectronic applications is missing to date. In this work, we present a comprehensive study of epitaxial graphene on technologically relevant and in a standard CMOS process achievable Ge(100) epilayers grown on Si(100) substrates. Crystalline graphene monolayer structures were grown by means of chemical vapor deposition (CVD). Using angle-resolved photoemission spectroscopy and in situ surface transport measurements, we demonstrate their metallic character both in momentum and real space. Despite numerous crystalline imperfections, e.g., grain boundaries and strong corrugation, as compared to epitaxial graphene on SiC(0001), charge carrier mobilities of 1 × 104 cm2/Vs were obtained at room temperature, which is a result of the quasi-charge neutrality within the graphene monolayers on germanium and not dependent on the presence of an interface oxide. The interface roughness due to the facet structure of the Ge(100) epilayer, formed during the CVD growth of graphene, can be reduced via subsequent in situ annealing up to 850 °C coming along with an increase in the mobility by 30%. The formation of a Ge(100)-(2 × 1) structure demonstrates the weak interaction and effective delamination of graphene from the Ge/Si(100) substrate.
Collapse
Affiliation(s)
- J Aprojanz
- Institut für Physik, Technische Universität Chemnitz, Chemnitz 09126, Germany
| | - Ph Rosenzweig
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - T T Nhung Nguyen
- Institut für Physik, Technische Universität Chemnitz, Chemnitz 09126, Germany
| | - H Karakachian
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - K Küster
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - U Starke
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany
| | - M Lukosius
- Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, Frankfurt (Oder) 15236, Germany
| | - G Lippert
- Leibniz-Institut für innovative Mikroelektronik, Im Technologiepark 25, Frankfurt (Oder) 15236, Germany
| | - A Sinterhauf
- IV. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - M Wenderoth
- IV. Physikalisches Institut, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - A A Zakharov
- MAX IV Laboratory and Lund University, Lund 22100, Sweden
| | - C Tegenkamp
- Institut für Physik, Technische Universität Chemnitz, Chemnitz 09126, Germany
| |
Collapse
|
3
|
Saeed M, Alshammari Y, Majeed SA, Al-Nasrallah E. Chemical Vapour Deposition of Graphene-Synthesis, Characterisation, and Applications: A Review. Molecules 2020; 25:E3856. [PMID: 32854226 PMCID: PMC7503287 DOI: 10.3390/molecules25173856] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 12/11/2022] Open
Abstract
Graphene as the 2D material with extraordinary properties has attracted the interest of research communities to master the synthesis of this remarkable material at a large scale without sacrificing the quality. Although Top-Down and Bottom-Up approaches produce graphene of different quality, chemical vapour deposition (CVD) stands as the most promising technique. This review details the leading CVD methods for graphene growth, including hot-wall, cold-wall and plasma-enhanced CVD. The role of process conditions and growth substrates on the nucleation and growth of graphene film are thoroughly discussed. The essential characterisation techniques in the study of CVD-grown graphene are reported, highlighting the characteristics of a sample which can be extracted from those techniques. This review also offers a brief overview of the applications to which CVD-grown graphene is well-suited, drawing particular attention to its potential in the sectors of energy and electronic devices.
Collapse
Affiliation(s)
- Maryam Saeed
- Energy and Building Research Centre, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109, Kuwait;
| | - Yousef Alshammari
- Waikato Centre for Advanced Materials, School of Engineering, The University of Waikato, Hamilton 3240, New Zealand;
| | - Shereen A. Majeed
- Department of Chemistry, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait;
| | - Eissa Al-Nasrallah
- Energy and Building Research Centre, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109, Kuwait;
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|