Origin of ambipolar graphene doping induced by the ordered Ge film intercalated on SiC(0001)

Kim, Hidong; Dugerjav, Otgonbayar; Lkhagvasuren, Altaibaatar; Seo, Jae M.

doi:10.1016/j.carbon.2016.07.010

Cited by 16 publications

(5 citation statements)

References 40 publications

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“…For comparison, monolayer graphene on 6H-SiC(0001) intercalated by one or two monolayers of Ge reveals a robust n- and p-type doping, where the Dirac point is around 300 meV below or above E F , respectively . Similarly, ambipolar doping schemes were reported for ordered intercalated Ge monolayer and bilayer and related to interface-induced charge transfer doping . Apparently, CVD-grown graphene on the present Ge epilayer is well delaminated, thus charge transfer via a proximity coupling is not effective.…”

Section: Resultsmentioning

confidence: 70%

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

Aprojanz

Rosenzweig

Nguyen

et al. 2020

ACS Appl. Mater. Interfaces

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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.

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Section: Resultsmentioning

confidence: 70%

“…37 Similarly, ambipolar doping schemes were reported for ordered intercalated Ge monolayer and bilayer and related to interface-induced charge transfer doping. 38 Apparently, CVDgrown graphene on the present Ge epilayer is well delaminated, thus charge transfer via a proximity coupling is not effective.…”

Section: Resultsmentioning

confidence: 80%

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

Aprojanz

Rosenzweig

Nguyen

et al. 2020

ACS Appl. Mater. Interfaces

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“…Especially attractive is the intercalation of species when both p-and n-doped phases could be retrieved depending on the amount of intercalated material. Among elements showing such ambivalent behavior most studied are Au [11,12] and Ge [13][14][15]. In case of germanium, two symmetrically doped (n-and p-type) phases that are characterized by different number of layers of intercalated Ge (1 ML and 2 ML for n-type and p-types, respectively) can be obtained.…”

Section: Introductionmentioning

confidence: 99%

Ambipolar Behavior of Ge-Intercalated Graphene: Interfacial Dynamics and Possible Applications

Zakharov

2021

Front. Phys.

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For the realization of graphene-based electronic and optic devices, the functionalization of this material becomes essential. Graphene doping through intercalation and tuning the chemical potential is one among other promising concepts. Intercalation of germanium is particularly interesting in view of its ambipolar doping behavior. Both p- and n-type doped graphene and their doping levels were identified by x-ray photoelectron emission microscopy (XPEEM), low-energy electron microscopy (LEEM), and angle-resolved photoemission microspectroscopy (μ-ARPES). The absolute amount of intercalated Ge was determined to be roughly 1 ML and 2 MLs for n- and p-phases, respectively. For the samples in the present study, we utilized the transition from 2 ML to 1 ML Ge via a mix phase after a high temperature annealing. Concrete implementation of mutual distribution of p- and n-phases depends on the temperature, mobility of Ge atoms in the second intercalated layer, and cooling/heating protocol, and can be nicely followed live in low-energy electron microscope (LEEM) during heating/cooling below 500°C. The process has a significant temperature hysteresis, which is an indication of the first-order phase transition. The enhanced Ge diffusion in the second layer can be suitable for tailoring ultrashort junction lengths so that pseudo-spin mismatch can be used in future electronic concepts. Another application can utilize the negative relative refractive index at the p–n boundary and can find possible applications in focusing electron optics.

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“…Intercalation of many species such as H, O, F, Au, Li, Na, Ge, Si and Yb [13][14][15][16][17][18][19][20][21][22] varied graphene doping in a wide range from n-doped to p-doped materials. Si and Ge, both from group IV, can be intercalated and effectively decouple the buffer layer from its supporting SiC substrate [19,20,23,24]. Si atoms can form two ordered structures at the interface depending on the annealing temperature, and the more ordered one obtained at higher temperature passivates the substrate more effectively with less electron doping [23].…”

Section: Introductionmentioning

confidence: 99%

“…Si atoms can form two ordered structures at the interface depending on the annealing temperature, and the more ordered one obtained at higher temperature passivates the substrate more effectively with less electron doping [23]. Ge, similar to Au [16], produces ambipolar doping depending on the amount of intercalated atoms [19,24]. The next element in the group, Sn, was found to decouple CVD graphene from its supporter, Ni(111), by forming a Sn/Ni (√3×√3) alloy interface [25].…”

Section: Introductionmentioning

confidence: 99%

Metal-dielectric transition in Sn-intercalated graphene on SiC(0001)

2017

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The Sn intercalation into a buffer layer graphene grown on 4H-SiC(0001) substrate has been studied with spectroscopic photoemission and low energy electron microscope. Both SnSi x and SnOx interfacial layers are found to form below the buffer layer, converting it into a quasi-freestanding monolayer graphene. Combining the various operation modes of the microscope allows a detailed insight into the formation processes of the interlayers and their thermal stability. In particular, at the interface we observed a reversible transition from silicide to oxide after exposure to ambient pressure and subsequent annealing. This metal-dielectric transition might be useful for interface engineering in graphene-based devices.

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Origin of ambipolar graphene doping induced by the ordered Ge film intercalated on SiC(0001)

Cited by 16 publications

References 40 publications

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

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

Ambipolar Behavior of Ge-Intercalated Graphene: Interfacial Dynamics and Possible Applications

Metal-dielectric transition in Sn-intercalated graphene on SiC(0001)

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