CVD graphene/Ge interface: morphological and electronic characterization of ripples

Mendoza, Cesar D.; Figueroa, Neileth S.; Costa, M.E.H. Maia da; Freire, F.L.

doi:10.1038/s41598-019-48998-1

Cited by 15 publications

(13 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The graphene film shows p-type doping with a doping level up to ~ 10∙10 12 cm −2 , not systematically depending on growth time. These findings are in good agreement with literature, where TCVD grown graphene films on Ge show predominantly compressive strain and p-type doping 23 , 39 , 45 , 46 . Pasternak et al 46 explained the compressive strain by the different thermal expansion coefficients of graphene (− 6 × 10 −6 K −1 ) 47 and Ge (+ 5.75 × 10 −6 K −1 ) 48 .…”

Section: Resultssupporting

confidence: 93%

Direct growth of graphene on Ge(100) and Ge(110) via thermal and plasma enhanced CVD

Bekdüz

Kaya

Langer

et al. 2020

Sci Rep

View full text Add to dashboard Cite

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.

show abstract

Section: Resultssupporting

confidence: 93%

Direct growth of graphene on Ge(100) and Ge(110) via thermal and plasma enhanced CVD

Bekdüz

Kaya

Langer

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…The corrugated (buckled) alignment observed here occurs to relax residual compressive strain imposed by the periodicity of the supercell. Similar substrate-induced corrugation or rippling of the graphene layer was also observed in the epitaxial growth of graphene on Ge 33 and SiC substrates, 34 and a DFT study of graphene on the diamond (111) surface is carried out. 35 Though this atomic distortion results in the modification of the local potential within the layer, it has a minimal effect on the electronic properties as discussed in the supplementary material.…”

mentioning

confidence: 54%

Structural and electronic properties of 2D (graphene, hBN)/H-terminated diamond (100) heterostructures

Mirabedini

Debnath

Neupane

et al. 2020

Applied Physics Letters

View full text Add to dashboard Cite

We report a first-principles study of the structural and electronic properties of two-dimensional (2D) layer/hydrogen-terminated diamond (100) heterostructures. Both the 2D layers exhibit weak van-der-Waals (vdW) interactions and develop rippled configurations with the H-diamond (100) substrate to compensate for the induced strain. The adhesion energy of the hexagonal boron nitride (hBN) layer is slightly higher, and it exhibits a higher degree of rippling compared to the graphene layer. A charge transfer analysis reveals a small amount of charge transfer from the H-diamond (100) surface to the 2D layers, and most of the transferred charge was found to be confined within the vdW gap. In the graphene/H-diamond (100) heterostructure, the semi-metallic characteristic of the graphene layer is preserved. On the other hand, the hBN/H-diamond (100) heterostructure shows semiconducting characteristics with an indirect bandgap of 3.55 eV, where the hBN layer forms a Type-II band alignment with the H-diamond (100) surface. The resultant conduction band offset and valence band offset are 0.10 eV and 1.38 eV, respectively. A thin layer of hBN offers a defect-free interface with the H-diamond (100) surface and provides a layer-dependent tunability of electronic properties and band alignment for surface-doped diamond field effect transistors.

show abstract

“…Nevertheless, also for these surfaces as well as on flat parts on the Ge(100) surfaces, a sinusoidal ripple formation is reported, apparently due to a compressive biaxial strain at the interface due to different thermal expansions. 21 Compared to the modulation of graphene on the hut cluster structures, the amplitudes of the sinusoidal ripples are two orders of magnitude smaller with only a small variation of the doping level (∼50 meV). Besides these characteristic imperfections, for graphene on Ge(110), the formation of wrinkles was reported as a result of the different thermal expansion coefficients during growth.…”

Section: Introductionmentioning

confidence: 91%

High-Mobility Epitaxial Graphene on Ge/Si(100) Substrates

Aprojanz

Rosenzweig

Nguyen

et al. 2020

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

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 × 10 4 cm 2 / 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.

show abstract

CVD graphene/Ge interface: morphological and electronic characterization of ripples

Cited by 15 publications

References 40 publications

Direct growth of graphene on Ge(100) and Ge(110) via thermal and plasma enhanced CVD

Direct growth of graphene on Ge(100) and Ge(110) via thermal and plasma enhanced CVD

Structural and electronic properties of 2D (graphene, hBN)/H-terminated diamond (100) heterostructures

High-Mobility Epitaxial Graphene on Ge/Si(100) Substrates

Contact Info

Product

Resources

About