Comparison of mobility extraction methods based on field-effect measurements for graphene

Zhong, Hua; Zhang, Zhiyong; Xu, Haitao; Qiu, Chenguang; Peng, Lian‐Mao

doi:10.1063/1.4921400

Cited by 80 publications

(70 citation statements)

References 26 publications

(27 reference statements)

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“…[ 12 ] The calculated Zeeman splitting energy E Z and its corresponding Zeeman field B Z are plotted against the external magnetic field in Figure 3b, respectively. The inset provides field effect mobility [ 50,51 ] (μ * ) versus carrier density of graphene/CrBr 3 heterostructures. High carrier mobility ensures the excellent device performance of 2D magnetic coupling and further observation of pronounced quantum oscillations.…”

Section: Figurementioning

confidence: 99%

Magnetic Proximity Effect in Graphene/CrBr₃ van der Waals Heterostructures

et al. 2020

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the third method, that is, the introduction of magnetism in graphene with the proximity effect in the interface of magnetic insulators and graphene. Pioneer works have been demonstrated with 3D bulk magnetic insulators like yttrium iron garnet, europium (II) sulfide, and bismuth ferrite. [7][8][9][10][11][12][13][14][15] Due to the short-range nature of the magnetic exchange coupling, a fully 2D van der Waals heterostructures is desired for downsizing the device and introducing magnetic proximity effect (MPE) at the same time. The recent profound discoveries of 2D ferromagnets [16][17][18][19][20][21][22][23][24][25][26][27][28][29] bring the possibility of 2D ferromagnetic van der Waals heterostructures, [30][31][32][33][34][35][36] it is urgent and essential to comprehensively investigate the magnetic coupling between graphene and 2D ferromagnetic materials for developing 2D spintronic devices. Not just the evidence of the existence of MPE in 2D ferromagnetic van der Waals heterostructures, [37,38] here, we report the direct observation of MPE in graphene/CrBr 3 van der Waals heterostructures by probing Zeeman spin Hall effect (ZSHE) through non-local transport measurements. A further quantitative estimation of Zeeman splitting field demonstrates a significant magnetic proximity exchange field even in a low magnetic field. Furthermore, we observe anomalous longitudinal resistance changes at the Dirac point R XX,D with increasing external magnetic field near ν = 0. This may attribute to the MPE induced ground state phases transformation of graphene from the ferromagnetic state at the lower magnetic field and a canted antiferromagnetic state at a higher field in quantum Hall regime.A typical graphene/CrBr 3 van der Waals heterostructure with Hall bar structure for electrical transport measurement is fabricated as shown in Figure 1a. In order to reach the best performance and a substantial MPE in graphene/CrBr 3 heterostructures, we optimize the fabrication process and conditions to achieve the desired heterostructures (see Experimental Section for details). The sample in the final stage is encapsulated and protected by poly(methyl methacrylate) (PMMA), which keeps the device surface away from the moisture and air for cryotemperature tests. The atomic structure of layered CrBr 3 is shown in Figure 1b. The Cr 3+ ions are configured in a honeycomb network, and the green arrows represent the spin direction of Cr atoms, which are found to exhibit a strong ferromagnetic coupling. [39][40][41][42][43][44] The Raman spectra of Figure 1c indicates that the monolayer graphene still preserves a high crystal quality when heterostructured with CrBr 3 layer. The optical image in 2D van der Waals heterostructures serve as a promising platform to exploit various physical phenomena in a diverse range of novel spintronic device applications. Efficient spin injection is the prerequisite for these devices. The recent discovery of magnetic 2D materials leads to the possibility of fully 2D van der Waals spintronics devices by implemen...

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Section: Figurementioning

confidence: 99%

Magnetic Proximity Effect in Graphene/CrBr₃ van der Waals Heterostructures

et al. 2020

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“…[26][27][28][29] The total resistance R t consists of channel resistance from MoS 2 channel (R channel and parameter resistance at source/drain contact (R c , which can be expressed by…”

Section: Materials Expressmentioning

confidence: 99%

High mobility top gated field-effect transistors and integrated circuits based on chemical vapor deposition-derived monolayer MoS<SUB>2</SUB>

Wu¹,

Zhang²,

Lv³

et al. 2016

Mat Express

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Monolayer MoS 2 with large area and high quality are grown using chemical vapor deposition (CVD) on Si/SiO 2 substrate, the triangle grain size is about 50 m, and top-gated field-effect transistors (FETs) were fabricated using atomic layer deposition (ALD) grown HfO 2 at low temperature as high-k gate insulator. The transistors present typical n-type field-effect properties, especially with high carrier mobility up to about 36.4 cm 2 /Vs, which is the highest value of mobility of top gated transistors based on CVD-derived single layer MoS 2 . Two kinds of methods were used to extract mobility from the measured properties of FETs, and the consistent results indicated the retrieved mobility was reliable. In addition an inverter circuit with gain larger than 1 was constructed based on the n-type FETs.

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“…The red circles show valley polarization estimated in the experiment. The doped carrier density n under gate voltage V Gate is estimated from the relationship of geometric capacitance and the back‐gate voltage using

n \approx \sqrt{n_{0}^{2} + {(| V_{Gate} - V_{0} | ε ε_{0} / t_{{SiO}_{2}})}^{2}}

, where n 0 is the residual carrier density, ε = 3.9 is the dielectric constant of silicon dioxide, ε 0 is the dielectric constant of vacuum, and

t_{{SiO}_{2}}

is the thickness of SiO 2 . The carrier density is defined to be positive (negative) under hole (electron) doped condition.…”

Section: Resultsmentioning

confidence: 99%

Continuous Control and Enhancement of Excitonic Valley Polarization in Monolayer WSe₂ by Electrostatic Doping

Shinokita

Wang

Miyauchi

et al. 2019

Adv Funct Materials

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Enhancement and continuous control of the excitonic valley polarization in electrostatically doped monolayer WSe 2 are demonstrated. Under excitation with circularly polarized light, 20% valley polarization of excitons around the charge neutrality condition at 70 K is increased to 40% by modulating the electron/hole density up to 2 × 10 12 cm −2 . This increase originates from slow valley relaxation for neutral exciton between the K and −K valleys owing to screening of longrange e-h exchange interactions by doped carriers. The gate-dependences of the exciton valley polarization at various temperatures are reproduced by theoretical calculations, which holds potential for next-generation valleytronic devices continuously controlled by an applied bias voltage.

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Comparison of mobility extraction methods based on field-effect measurements for graphene

Cited by 80 publications

References 26 publications

Magnetic Proximity Effect in Graphene/CrBr₃ van der Waals Heterostructures

Magnetic Proximity Effect in Graphene/CrBr₃ van der Waals Heterostructures

High mobility top gated field-effect transistors and integrated circuits based on chemical vapor deposition-derived monolayer MoS<SUB>2</SUB>

Continuous Control and Enhancement of Excitonic Valley Polarization in Monolayer WSe₂ by Electrostatic Doping

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Comparison of mobility extraction methods based on field-effect measurements for graphene

Cited by 80 publications

References 26 publications

Magnetic Proximity Effect in Graphene/CrBr3 van der Waals Heterostructures

Magnetic Proximity Effect in Graphene/CrBr3 van der Waals Heterostructures

High mobility top gated field-effect transistors and integrated circuits based on chemical vapor deposition-derived monolayer MoS<SUB>2</SUB>

Continuous Control and Enhancement of Excitonic Valley Polarization in Monolayer WSe2 by Electrostatic Doping

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Magnetic Proximity Effect in Graphene/CrBr₃ van der Waals Heterostructures

Magnetic Proximity Effect in Graphene/CrBr₃ van der Waals Heterostructures

Continuous Control and Enhancement of Excitonic Valley Polarization in Monolayer WSe₂ by Electrostatic Doping