Growth and electronic structure of graphene on semiconducting Ge(110)

The implementation of graphene in semiconducting technology requires precise knowledge about the graphene-semiconductor interface. In our work the structure and electronic properties of the graphene/n-Ge(110) interface are investigated on the local (nm) and macro (from μm to mm) scales via a combination of different microscopic and spectroscopic surface science techniques accompanied by density functional theory calculations. The electronic structure of freestanding graphene remains almost completely intact in this system, with only a moderate n-doping indicating weak interaction between graphene and the Ge substrate. With regard to the optimisation of graphene growth it is found that the substrate temperature is a crucial factor, which determines the graphene layer alignment on the Ge(110) substrate during its growth from the atomic carbon source. Moreover, our results demonstrate that the preparation route for graphene on the doped semiconducting material (n-Ge) leads to the effective segregation of dopants at the interface between graphene and Ge(110). Furthermore, it is shown that these dopant atoms might form regular structures at the graphene/Ge interface and induce the doping of graphene. Our findings help to understand the interface properties of the graphene-semiconductor interfaces and the effect of dopants on the electronic structure of graphene in such systems.

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“…[21]. These results are consistent with our previous preliminary data [25] as well as with present results (see also discussion below).…”

Section: Resultssupporting

confidence: 94%

“…As was shown earlier in Ref. 25, these spots can be assigned to two types of graphene domains, which are misoriented by ±15 • with respect to the graphene singledomain orientation observed earlier [15,17,26,27] and in the present work (see below).…”

Section: Resultssupporting

confidence: 85%

The graphene/n-Ge(110) interface: structure, doping, and electronic properties

et al. 2018

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“…This reflection could be due to a minority of graphene domains with different crystalline orientation rotated by 30° with respect to the dominant one. The formation of such domains has been observed in the literature [15] as an additional subset of spots rotated by 30° in c-LEED. In contrast, in our case, these spots are not visible in c-LEED, indicating that this second orientational domain is clearly marginal.…”

Section: Fig 3 Graphene Sample Deposited At Td= Tc= 930 °C: (A) Honmentioning

confidence: 63%

Driving with temperature the synthesis of graphene on Ge(110)

Persichetti

Seta

Scaparro

et al. 2020

Applied Surface Science

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By tuning the growth parameters, we show that it is possible to drive the CVD synthesis of graphene on Ge(110) towards the formation of either ultrathin armchair nanoribbons or of continuous graphene films.The ribbons are aligned along specific high-symmetry directions of the Ge(110) surface and have a width of ~5 nm. Moreover, by merging spectroscopic and morphological information, we find that the quality of graphene films depends critically on the growth temperature improving significantly in a narrow range close to the Ge melting point. The abruptness of the temperature behavior observed indicates that achieving high-quality graphene is intimately connected to the quasi-liquid Ge layer formed close to 930 °C on the substrate. Being observed for diverse Ge orientations, this process, known as incomplete melting, is shown to be of general relevance for graphene synthesis on Ge, and explains why similar growth conditions present in literature lead to graphene of very diverse quality on these substrates.

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“…The main bottleneck to unlocking graphene's potential is developing metal-free deposition techniques compatible with the standard CMOS paradigm [10]. To this end, the catalysed chemical vapor deposition (CVD) of graphene on Ge or Ge/Si substrates [11][12][13][14][15][16][17][18] is a promising route for overcoming the issue of metallic contamination inherently associated with the well-established CVD synthesis of graphene on metals or with the transfer process from metallic templates [19][20][21]. Besides being intrinsically compatible with Si-based processing technology, Ge is well-suited as a catalytically-active substrate for promoting the decomposition of carbon precursors and the formation of a graphene phase, due to the low solubility of C in Ge and the absence of a stable Ge carbide.…”

Section: Introductionmentioning

confidence: 99%

Abrupt changes in the graphene on Ge(001) system at the onset of surface melting

Persichetti

Gaspare

Fabbri

et al. 2019

Carbon

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By combining scanning probe microscopy with Raman and x-ray photoelectron spectroscopies, we investigate the evolution of CVD-grown graphene/Ge(001) as a function of the deposition temperature in close proximity to the Ge melting point, highlighting an abrupt change of the graphene's quality, morphology, electronic properties and growth mode at 930 °C. We attribute this discontinuity to the incomplete surface melting of the Ge substrate and show how incomplete melting explains a variety of diverse and long-debated peculiar features of the graphene/Ge(001), including the characteristic nanostructuring of the Ge substrate induced by graphene overgrowth. We find that the quasi-liquid Ge layer formed close to 930 °C is fundamental to obtain high-quality graphene, while a temperature decrease of 10 degrees already results in a wrinkled and defective graphene film.

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Growth and electronic structure of graphene on semiconducting Ge(110)

Cited by 26 publications

References 57 publications

The graphene/n-Ge(110) interface: structure, doping, and electronic properties

The graphene/n-Ge(110) interface: structure, doping, and electronic properties

Driving with temperature the synthesis of graphene on Ge(110)

Abrupt changes in the graphene on Ge(001) system at the onset of surface melting

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