Operation of Graphene Transistors at Gigahertz Frequencies

Lin, Yu-Ming; Jenkins, K.A.; Valdes‐Garcia, Alberto; Small, Joshua P.; Farmer, Damon B.; Avouris, Phaedon

doi:10.1021/nl803316h

Cited by 1,018 publications

(756 citation statements)

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“…Although several high-k inorganic dielectrics, such as HfO 2 , Al 2 O 3 , and ZrO 2 , have been applied to the fabrication of graphene FETs, they cannot be available for flexible devices based on plastic substrates due to their high growth temperature. 8,12,13 This paper reports a promising method for fabricating a low-voltage operating graphene FET array on plastic substrates using an ion gel as the gate dielectric. The ion gel consists of a room temperature ionic liquid and gelating triblock copolymer, which exhibits an extremely high capacitance of 5.17 µF/cm 2 .…”

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confidence: 99%

High-Performance Flexible Graphene Field Effect Transistors with Ion Gel Gate Dielectrics

et al. 2010

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A high-performance low-voltage graphene field-effect transistor (FET) array was fabricated on a flexible polymer substrate using solution-processable, high-capacitance ion gel gate dielectrics. The high capacitance of the ion gel, which originated from the formation of an electric double layer under the application of a gate voltage, yielded a high on-current and low voltage operation below 3 V. The graphene FETs fabricated on the plastic substrates showed a hole and electron mobility of 203 ( 57 and 91 ( 50 cm 2 /(V · s), respectively, at a drain bias of -1 V. Moreover, ion gel gated graphene FETs on the plastic substrates exhibited remarkably good mechanical flexibility. This method represents a significant step in the application of graphene to flexible and stretchable electronics.KEYWORDS Graphene, ion gel, flexible electronics, field effect transistor, low-voltage operation G raphene has attracted attention for a range of electronic applications, such as displays, solar cells, and sensors owing to its exceptional electronic and optoelectronic properties. [1][2][3][4] Recent developments in the large area synthesis of high-quality graphene films has created new pathways for the application of graphene to highfrequency devices. [5][6][7] There are two general approaches for fabricating graphene devices over large areas: one that employs graphene grown directly on SiC wafers 8 and another that transfers graphene films synthesized on metal layers to other useful substrates. 9,10 The latter approach is attractive because of the special attributes of graphene films, such as flexible/stretchable device fabrication and the possibility of fabrication over large areas. This approach has produced device arrays on rigid insulating wafers and is scalable to a wafer size. 9 Although several studies have reported graphene field-effect transistors (FETs) on a plastic substrate, 11 there are still significant challenges in fabricating large scale, flexible graphene FETs.Exploring graphene for flexible electronics requires solution-processable, high-capacitance gate dielectrics that can form at low temperature with a good interface with the graphene films transferred to plastic sheets. Although several high-k inorganic dielectrics, such as HfO 2 , Al 2 O 3 , and ZrO 2 , have been applied to the fabrication of graphene FETs, they cannot be available for flexible devices based on plastic substrates due to their high growth temperature. 8,12,13 This paper reports a promising method for fabricating a low-voltage operating graphene FET array on plastic substrates using an ion gel as the gate dielectric. The ion gel consists of a room temperature ionic liquid and gelating triblock copolymer, which exhibits an extremely high capacitance of 5.17 µF/cm 2 . [14][15][16] The high capacitance of the ion gel gate dielectrics in the graphene FETs provides both high on-current and low voltage operation. Furthermore, ion gel gated graphene FETs fabricated on plastic substrates show very good mechanical flexibility.Before the fabric...

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High-Performance Flexible Graphene Field Effect Transistors with Ion Gel Gate Dielectrics

et al. 2010

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“…The thin film is not able to grow directly on graphene or CNTs, except for edges or where there are defects as shown in Figure 4(a), so they need functionalization before the ALD growth [62,63]. Non-covalent functionalization layer (NCFL) can be formed prior to ALD growth via molecules like DNA [62], 3,4,9,10-perylene tetracarboxylic acid (PTCA) [63], and NO 2 shown in Figure 4(b) [64][65][66][67]. Besides molecules, polymer can also play the role of NCFL, such as NFC polymers [54,68,69], and ozone pre-treatment (Figure 4(c)) is proved to work for ALD growth as well [70].…”

Section: High-κ Dielectric Growth On Graphenementioning

confidence: 99%

“…Moreover, directly constructing nucleation layer via oxidation of thin film of evaporated or sputtered Al (several nm), followed by Al 2 O 3 ALD growth, is also a choice to form dielectric on graphene surface [71,72]. Unfortunately, functionalization will cause some problems, such as introducing extra scattering centers and surface damages, hence reducing the current and transconductance as shown in Figure 4(d) [67,73]. The interlayer functional molecule will also introduce a gap between the channel and gate oxide, largely reducing the gate modulation efficiency, and hence weakening the transistor performance.…”

Section: High-κ Dielectric Growth On Graphenementioning

confidence: 99%

Graphene-based ambipolar electronics for radio frequency applications

2012

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Graphene is considered as a promising material to construct field-effect transistors (FETs) for high frequency electronic applications due to its unique structure and properties, mainly including extremely high carrier mobility and saturation velocity, the ultimate thinnest body and stability. Through continuously scaling down the gate length and optimizing the structure, the cut-off frequency of graphene FET (GFET) was rapidly increased and up to about 300 GHz, and further improvements are also expected. Because of the lack of an intrinsic band gap, the GFETs present typical ambipolar transfer characteristic without off state, which means GFETs are suitable for analog electronics rather than digital applications. Taking advantage of the ambipolar characteristic, GFET is demonstrated as an excellent building block for ambipolar electronic circuits, and has been used in applications such as highperformance frequency doublers, radio frequency mixers, digital modulators, and phase detectors. Owing to the success isolation of single layer graphene by Novoselov et al. [4] in 2004, the obsolete point was broken down and a tremendous research field has been expanded based on the 2D material [5][6][7][8][9][10][11], and even the 2010 Nobel Prize in Physics was awarded jointly to A. K. Geim and K. S. Novoselov "for groundbreaking experiments regarding the two-dimensional material graphene" [12,13]. The special 2D structure of graphene provides a series of unique properties in mechanics, thermology, optics, and electronics [10,11,[14][15][16][17][18][19]. Graphene not only provides an experimental platform for basic physics, such as relativistic quantum mechanics (or quantum electrodynamics), which is due to the *Corresponding authors (email: zyzhang@pku.edu.cn; lmpeng@pku.edu.cn) massless property of the Dirac fermion behaved electrons in graphene [20][21][22], but also manifests promising application potential in numerous application fields, such as analog radio frequency (RF) field-effect transistors (FETs) [10,[23][24][25], flexible transparent electrodes and touch screen [26], photodetection [11,27,28], and spin transport [29,30]. In this review article, we will focus on the graphene based electronics and applications, especially RF performance of graphene and ambipolar electronics.

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“…[6][7][8][9][10][11] The realization of high-speed basic circuit components 12,13) has emphasized the need for highperformance digital units using graphene, and several logic inverter devices have been demonstrated using mechanically exfoliated graphene at cryogenic temperatures. [14][15][16][17] However, these devices have been a real challenge due to some unique properties of graphene, such as the ambipolarity and the zero bandgap, which led to undesirable imperfect complementary logic operation with excessive on/off state current resulting in input/output logic-level mismatch, therefore, their performances are still not comparable to silicon complimentary metal-oxide-semiconductor (CMOS), and far from the practical requirements.…”

Section: Introductionmentioning

confidence: 99%