guest ::
| Home > Workflow collections > In process > Metal-free chemical vapor deposition of single-layer graphene and hexagonal boron nitride films on c-plane sapphire for electronic devices |
| Home > Workflow collections > In process > Metal-free chemical vapor deposition of single-layer graphene and hexagonal boron nitride films on c-plane sapphire for electronic devices |
| Book/Dissertation / PhD Thesis | FZJ-2026-03918 |
2026
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-993-0
This record in other databases:
Abstract: The rapid growth of information technology (IT), which will continue to increase in the future thanks to applications of artificial intelligence (AI), is generating an exponential rise in energy consumption by IT. Mitigating this increase requires significantly more energy-efficient information storage and processing than the classic von Neumann architectures based on complementary silicon semiconductor technology (CMOS). Therefore, intensive research is currently being conducted into new algorithms and new computer architectures, such as neuromorphic and quantum computing, as well as new components, such as memristors, and new materials. Twodimensional (2D) materials, in which atoms are bound in layers and the layers are connected via van derWaals bonds, have great potential for future IT applicationsand beyond due to their unique physical and chemical properties. The successful integration of novel 2D materials with CMOS chips opens up new fields of application in the areas of "More Moore" and "Beyond Moore," which can contribute to solving the energy problem of modern IT. One challenge for the use of 2D materials is to develop CMOS-compatible materials and growth processes as well as suitable transfer processes to pre-processed silicon wafers. Intensive research is being conducted worldwide in this area. Metal organic chemical vapor deposition (MOCVD) is a scalable process established in semiconductor technology for the growth of defect-free, thin, single-crystal layers. Therefore, one branch of research, which is also being pursued in the European Union’s "Graphene Flagship Project," aims to deposit single-crystal layers of 2D materials on suitable growth substrates using MOCVD and, in a second step, transfer them to CMOS substrates. In the recent past, the search for suitable growth substrates has been guided by the desire to reduce the high growth temperatures by using catalytic effects for the decomposition of the reactants in the CVD process. Copper foil has proven particularly suitable for this purpose. However, residual copper contamination in the 2D material at a concentration that exceeds the tolerances of CMOS technology prompted the search for CMOS-compatible growth substrates in the form of singlecrystal wafers, on the one hand for the subsequent transfer of the layers and on the other hand for the construction of component structures with the possibility of direct use on the chip, which requires insulating substrates. Single-crystal substrates made of sapphire (Al2O3, corundum) are well established in the electro-optical industry and are cost-effective, with high purity, available in substrate sizes up to 300 mm in diameter. The c-plane with its hexagonal surfaceis particularly interesting as a growth template for 2D materials, as evidenced by numerous high-profile publications. It is important to note that the quality of layers made of 2D materials grown on sapphire still lags significantly behind those achieved on copper. This is particularly evident for single-layer graphene (SLG), which, when grown on copper, exhibits charge carrier mobilities at room temperature of up to 68000cm2/Vs, while graphene grown on sapphire achieved a maximum of 6000cm2/Vs. One reason for this is the significantly higher density of grain boundaries for SLG on sapphire. Despite numerous studies on the relationship between the physical and electrical properties of layers of 2D materials, only a few deal with the mechanisms for growth on sapphire. The effects of various pretreatmentsof sapphire are generally discussed phenomenologically. This thesis therefore presents a detailed investigation of the growth of single-layer graphene and thin layers of hexagonal boron nitride (h-BN) on c-plane-oriented sapphire substrates. The (MO)CVD processes were carried out in an AIXTRON SE cold wall 2D R&D Close Coupled Showerhead (CCS®) reactor in a 7x2" configuration. Thanks to the scalable reactor concept, the results presented are transferable to industrial processes. Furthermore, in-situ reflectivity measurements with an integrated EpiTT® system from Laytec provide information on surface coverage during the growth process. Methane, hydrogen, and argon or triethylborane, ammonia, and hydrogen of the highest purity were used for the (MO)CVD processes of SLG and h-BN. The growth studies include orientation, miscut, and pretreatment of the sapphire substrate as well as process variations such as flow rates and temperature profiles combined with nanoscale physical and structural analytical methods.
|
The record appears in these collections: |
PDF