Spontaneous intercalation of Ga and In bilayers during plasma-assisted molecular beam epitaxy growth of GaN on graphene on SiC

Feldberg, Nathaniel; Klymov, Oleksii; Garro, N.; Cros, A.; Mollard, Nicolas; Okuno, Hanako; Gruart, Marion; Daudin, B.

doi:10.1088/1361-6528/ab261f

Cited by 16 publications

(19 citation statements)

References 36 publications

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“…Although the intercalation of H, Ga, Sn, and In underneath the buffer layer of EMLG has been demonstrated by others using non-engineered EMLG samples, [17,32,63,75,92] the engineering of defects (i.e., multi-atomic discontinuities in the graphene) can significantly promote intercalation. [31,68,91] The engineered defects in these previous works were of relatively high density, with a separation of ≈300-700 nm, [31] or directly observable in the C 1s spectra as judged with a lab-based XPS. [68] Our work differs from these previous efforts in that the patterning of the substrate does not necessarily need to be in such high density in order to greatly facilitate intercalation.…”

Section: Resultsmentioning

confidence: 97%

“…Our patterned lines have a dimension of 2 × 2600 µm 2 , and are separated by 200 µm, in stark contrast with previous efforts. [31,68,91] Our "defect-free" areas are at least three orders of magnitude greater, and thus, have the benefit of large defect-free areas in which devices could be fabricated. Furthermore, we have demonstrated that the rate of Mg-intercalation increases proportionally with the increase in graphene edge length.…”

Section: Resultsmentioning

confidence: 99%

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Increasing the Rate of Magnesium Intercalation Underneath Epitaxial Graphene on 6H‐SiC(0001)

Kotsakidis

Currie

Čabo

et al. 2021

Adv Materials Inter

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in condensed matter physics experiments due to its ease of production (typically via micromechanical cleavage) [1,2] and access to novel physics owing to its linear "Dirac" band structure at low energy. [3,4] But for graphene to be useful in device applications, we must be able to engineer [5] its electrical properties. To achieve this, various techniques such as surface chemical doping [6] or atom substitution (see refs. [5,7] for a brief review of these methods), gating, [8][9][10][11][12][13] proximity effects, [8,14] stacking, [15,16] and intercalation [17][18][19][20][21][22][23][24][25] (see ref. [26] for a brief review of intercalation) have been applied. Of these techniques, intercalation (i.e., the insertion of atoms or molecules beneath or in-between graphene sheets) has been demonstrated as a relatively simple and versatile method for achieving control over graphene's key electrical properties-carrier type, [17][18][19]21] conductivity, [20,[27][28][29] and bandgap. [25,30] For instance, engineering the carrier type and bandgap via intercalation could enable graphene p-n junctions [31][32] and transistors. [33] Whereas increasing graphene's conductivity via intercalation could enable highly conductive and transparent electrodes for solar cells, [34] interconnects, [35] or new superconductors. [20,36] Many of the intercalation experiments to date have utilized epitaxially synthesized graphene on SiC (either the 4H-or 6H-polytype on the (0001) orientation, i.e., silicon Magnesium intercalated "quasi-freestanding" bilayer graphene on 6H-SiC(0001) (Mg-QFSBLG) has many favorable properties (e.g., highly n-type doped, relatively stable in ambient conditions). However, intercalation of Mg underneath monolayer graphene is challenging, requiring multiple intercalation steps. Here, these challenges are overcome and the rate of Mg intercalation is significantly increased by laser patterning (ablating) the graphene to form micron-sized discontinuities. Low energy electron diffraction is then used to verify Mg-intercalation and conversion to Mg-QFSBLG, and X-ray photoelectron spectroscopy to determine the Mg intercalation rate for patterned and non-patterned samples. By modeling Mg intercalation with the Verhulst equation, it is found that the intercalation rate increase for the patterned sample is 4.5 ± 1.7. Since the edge length of the patterned sample is ≈5.2 times that of the non-patterned sample, the model implies that the increased intercalation rate is proportional to the increase in edge length. Moreover, Mg intercalation likely begins at graphene discontinuities in pristine samples (not step edges or flat terraces), where the 2D-like crystal growth of Mg-silicide proceeds. The laser patterning technique may enable the rapid intercalation of other atomic or molecular species, thereby expanding upon the library of intercalants used to modify the characteristics of graphene, or other 2D materials and heterostructures.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Increasing the Rate of Magnesium Intercalation Underneath Epitaxial Graphene on 6H‐SiC(0001)

Kotsakidis

Currie

Čabo

et al. 2021

Adv Materials Inter

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“…The bright line visible above SiC corresponds to the intercalation of a 2 monolayer (ML) thick pure Ga layer under graphene. It was recently established that the formation of this metallic bilayer is mediated by metal diffusion from the defective graphene regions on SiC steps and further promoted during growth by the additional defects created by N-plasma in graphene [14].…”

Section: Resultsmentioning

confidence: 99%

“…Also, exposure to N plasma leads to homogeneization of graphene doping and strain state. [14]. In this context, it appears necessary to investigate the interplay between metallic/N fluxes and graphene during the first stages of the epitaxial growth of GaN by MBE.…”

Section: Introductionmentioning

confidence: 99%

Impact of kinetics on the growth of GaN on graphene by plasma-assisted molecular beam epitaxy

et al. 2019

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The growth of GaN on graphene by molecular beam epitaxy was investigated. The most stable epitaxial relationship, i.e. [00.1]-oriented grains, is obtained at high temperature and Nrich conditions, which match those for nanowire growth. Alternatively, at moderate temperature and Ga-rich conditions, several metastable orientations are observed at the nucleation stage, which evolve preferentially towards [00.1]-oriented grains. The dependence of the nucleation regime on growth conditions was assigned to Ga adatom kinetics. This statement is consistent with the calculated graphene/GaN in-plane lattice coincidence and supported by a combination of transmission electron microscopy, X-ray diffraction, photoluminescence, and Raman spectroscopy experiments.

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“…demonstrated in the case of graphene, exposure to N plasma produces electronic and structural defects[23]. As the mica surface is terminated by a layer of Si/Al atoms tetrahedrally coordinated to O, and due to high chemical reactivity of N with Si, it is expected that N ions from the plasma can react with the surface.…”

mentioning

confidence: 99%

Growth of zinc-blende GaN on muscovite mica by molecular beam epitaxy

et al. 2020

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The mechanisms of plasma-assisted molecular beam epitaxial growth of GaN on muscovite mica were investigated. Using a battery of techniques, including scanning and transmission electron microscopy, atomic force microscopy, cathodoluminescence, Raman spectroscopy and X-ray diffraction, it was possible to establish that, in spite of the lattice symmetry mismatch, GaN grows in epitaxial relationship with mica, with the [11-20] GaN direction parallel to [010] direction of mica. GaN layers could be easily detached from the substrate via the delamination of the upper layers of the mica itself, discarding the hypothesis of a van der Waals growth mode. Mixture of wurtzite (hexagonal) and zinc blende (cubic) crystallographic phases was found in the GaN layers with ratios highly dependent on the growth conditions. Interestingly, almost pure zinc blende GaN epitaxial layers could be obtained at high growth temperature, suggesting the existence of a specific GaN nucleation mechanism on mica and opening a new way to the growth of the thermodynamically less stable zinc blende GaN phase.

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Spontaneous intercalation of Ga and In bilayers during plasma-assisted molecular beam epitaxy growth of GaN on graphene on SiC

Cited by 16 publications

References 36 publications

Increasing the Rate of Magnesium Intercalation Underneath Epitaxial Graphene on 6H‐SiC(0001)

Increasing the Rate of Magnesium Intercalation Underneath Epitaxial Graphene on 6H‐SiC(0001)

Impact of kinetics on the growth of GaN on graphene by plasma-assisted molecular beam epitaxy

Growth of zinc-blende GaN on muscovite mica by molecular beam epitaxy

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