Patterned Carbon Nanotube Thin-Film Transistors with Transfer-Print Assembly

Sangwan, Vinod K.; Hines, D. R.; Ballarotto, V. W.; Esen, G.; Fuhrer, Michael S.; Williams, Ellen D.

doi:10.1557/proc-0963-q10-57

Cited by 9 publications

(13 citation statements)

References 23 publications

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“…In the post-growth method, CNT thin films are selectively removed after growth with a transfer printing method. We have previously shown that CNTs can be transferred from SiO 2 to thermoplastics (polyterephthalate (PET)) [10,11] and metallic substrates (Au and Pd) [12]. This means that pristine CNTs can be patterned by printing onto stamps made from these materials, thus a transfer printing method using stamps of PET and Au was developed.…”

Section: B Patterning Cnt Thin Filmsmentioning

confidence: 99%

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Controlled growth, patterning and placement of carbon nanotube thin films

Sangwan

Ballarotto

Hines

et al. 2009

2009 International Semiconductor Device Research Symposium

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This abstract is for oral presentation.Carbon nanotube (CNT) thin films are promising electronic materials for a wide range of applications, such as large area transparent and flexible electronics [1], supercapacitors [2], and solar cells [3]. Because the electrical response of a random network of CNTs is determined by percolation of both metallic and semiconducting CNTs, the density of the CNTs determines the electrical behavior of a CNT thin film [4]. Thus, it is possible to realize different CNT-device components by controlling the density. In addition, it is essential to pattern CNT thin films to define individual device components. However, different applications require different patterning approaches. For large area integrated circuits, CNT thin films must be patterned with high resolution and low edge roughness. For flexible electronics on plastic substrates, the patterned CNT thin films must be compatible with additional fabrication steps such as transfer printing. To probe the intrinsic physical properties of CNTs, as-grown CNT thin film patterns are desired without any chemical exposure. Finally, to fully realize the potential of CNT thin film as electronic materials in flexible electronics, patterned CNT thin films have to be placed onto different substrates. Here, we report on controlled growth, patterning, and placement methods that meet these requirements.Chemical vapor deposition (CVD) was used to grow CNT thin films. The density of CNTs was controlled by systematically varying the density of catalyst nanoparticles (ferric nitrate) on the thermally oxidized Si growth substrate. The resulting CNT thin films had densities ranging from ~ 5 CNTs/100 m 2 to ~ 300 CNTs/100 m 2 (Fig. 1).Initially the CNT thin films can be patterned in two ways. In the first method, CNTs are grown from pre-patterned catalyst particles. In the second method, CNT thin films are patterned by photolithography after the growth. In the first case, CNTs pattern remain pristine, but the edge roughness of patterns is determined by length of CNTs (~ 10 m). In the second case, a good edge roughness (< 1 m) is achieved, but CNTs are exposed to processing chemicals. The disadvantages of these two approaches can be avoided by patterning CNT thin film using an alternative approach.We used transfer printing approach to pattern as-grown CNT thin films. This was achieved by selectively transfer printing CNTs from the growth substrate to thermoplastic (polyterephthalate) or metallic (Au) stamps, see Fig. 2(a) and (b). Fig. 2 (c) shows parallel arrays of CNT thin films patterned by using Au stamps. These pristine CNT thin film patterns have high resolution (up to 5 m), low edge roughness (~ 1 m).We employed transfer printing methods to place patterned CNT thin films on different substrates. High quality CNT thin film transistors (TFT) were fabricated on PET substrates, incorporating poly(methyl methacrylate) as the gate dielectric and Au as the electrode material. CNT TFTs were demonstrated with field effect mobility up to 20 cm 2 /Vs with o...

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Section: B Patterning Cnt Thin Filmsmentioning

confidence: 99%

“…Controlled placement of patterned CNT films can achieved by transfer printing [10,11] when proper differential adhesion exists between the CNT/SiO 2 substrate and device substrate. This is ensured by using the release layer mentioned in previous section.…”

Section: C Controlled Placement Of Patterned Cnt Thin Filmsmentioning

confidence: 99%

Controlled growth, patterning and placement of carbon nanotube thin films

Sangwan

Ballarotto

Hines

et al. 2009

2009 International Semiconductor Device Research Symposium

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“…These techniques have produced high-quality, light-weight, flexible devices. [8][9][10][11] This process has the potential to be scaled-up for roll-to-roll manufacturing. 12,13 Transfer printing relies primarily on differential adhesion where a printable layer deposited (and possible patterned) onto one substrate (the transfer substrate) is pressed against a second substrate (the device substrate).…”

Section: Introductionmentioning

confidence: 99%

Transfer printing as a method for fabricating hybrid devices on flexible substrates

et al. 2007

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Printing methods are becoming important in the fabrication of flexible electronics. A transfer printing method has been developed for the fabrication of organic thin-film transistors (OTFT), capacitors, resistors and inductors onto plastic substrates. The method relies primarily on differential adhesion for the transfer of a printable layer from a transfer substrate to a device substrate. A range of materials applications is illustrated, including metals, organic semiconductors, organic dielectrics, nanotube and nanowire mats, a patterned inorganic semiconductor and graphene. Transfer printing can be used to create complex structures including many disparate materials sequentially printed onto the flexible substrate, with no mixed processing steps performed on the device substrate. Specifically, the fabrication and performance of model OTFT devices consisting of a polyethylene terephthalate (PET) substrate, gold (Au) gate and source/drain electrodes, a poly(methyl methacrylate) (PMMA) dielectric layer and either a pentacene (Pn) or a poly(3-hexylthiophene) (P3HT) organic semiconductor layer will be presented. These transfer printed OTFTs on plastic outperform non-printed devices on a Si substrate with a SiO 2 dielectric layer (SiO 2 /Si). Transfer printed Pn OTFTs on a plastic substrate have exhibited mobilities of 0.237 cm 2 /Vs, compared to non-printed Pn OTFTs on a SiO 2 /Si substrate with mobilities of 0.1 cm 2 /Vs. Transfer printed P3HT TFTs on a plastic substrate have exhibited mobilites of 0.04 cm 2 /Vs, compared to non-printed P3HT TFTs on a SiO 2 /Si substrate with mobilities of 0.007 cm 2 /Vs.

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“…A wide variety of materials have been utilized in the fabrication of thin-film transistors (TFT) and mechanical resonators. Thin-film transistors with active layers of Pentacene (Pn), poly(3-hexylthiophene) (P3HT), carbon nanotube mats (CNTM), graphene and silicon (Si) nano-ribbons have all been fabricated with a polymethylmethacrylate (PMMA) dielectric layer on a polyethylene terephthalate (PET) substrate [1,2,3,4]. Figure 1 shows optical micrographs of (a) CNTM, (b) graphene and (c) Si nano-ribbon devices.…”

mentioning

confidence: 99%

Electronic and mechanical systems printed onto flexible substrates

Hines

Huang

Williams

et al. 2009

2009 International Semiconductor Device Research Symposium

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Printing methodologies that combine capabilities from both nanoimprint lithography (NIL) and transfer printing (TP) have been utilized to fabricate electronic and mechanical device components onto plastic substrates. A wide variety of materials have been utilized in the fabrication of thin-film transistors (TFT) and mechanical resonators. Thin-film transistors with active layers of Pentacene (Pn), poly(3-hexylthiophene) (P3HT), carbon nanotube mats (CNTM), graphene and silicon (Si) nano-ribbons have all been fabricated with a polymethylmethacrylate (PMMA) dielectric layer on a polyethylene terephthalate (PET) substrate [1,2,3,4]. Figure 1 shows optical micrographs of (a) CNTM, (b) graphene and (c) Si nano-ribbon devices. The performance of each of these devices on plastic is as good as that for non-printed devices fabricated using a SiO 2 dielectric layer on a Si substrate. The most recently fabricate Si nanoribbon TFT devices have been doped n-type and exhibit an electron mobility of 144 cm 2 /Vs. Mechanical resonators constructed from both Si features and thin Au-coated polymer films are shown in figure 2. These structures were aligned and printed over a previously printed cavity on a polycarbonate (PC) substrate. The mechanical response of these structures was measured optically in air using an AC voltage applied to a probe tip to actuate the resonator. For a Si resonator of thickness 70 nm and area 10,000 μm 2 a resonance frequency of approximately 480 KHz was measured (Fig. 2a). For a 200 nm thick PC film coated with 35 nm of Au and area 10,000μm 2 , a resonance frequency of approximately 520 KHz was measured for the highly strained (note wrinkle pattern in Au layer) device shown in Fig. 2b and of approximately 35 KHz for the relatively unstrained device shown in Fig. 2c. Preliminary calculations suggest a fundamental resonant frequency of 42 KHz for the Si resonator (Fig. 2a) and 80 KHz for the (unstrained) Au coated PC film (Fig. 2c). Differences between measured and calculated frequencies are most likely related to strain in the printed structures. Similar printing methods have been used to fabricated transistors, resistors, capacitors, inductors and mechanical resonators onto plastic substrates in an additive process that does not require the use of chemical processing on the device substrate. The transfer printing process can thus be used to build circuits based on dissimilar materials in ways not possible with standard lithographic methods. For example, an array containing both inorganic, metallic and polymeric resonators could be printed onto a common substrate. Details of the printing methods and characteristics of the resulting devices will be presented as a function of membrane material, thickness, printing conditions and cavity dimensions.

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Patterned Carbon Nanotube Thin-Film Transistors with Transfer-Print Assembly

Cited by 9 publications

References 23 publications

Controlled growth, patterning and placement of carbon nanotube thin films

Controlled growth, patterning and placement of carbon nanotube thin films

Transfer printing as a method for fabricating hybrid devices on flexible substrates

Electronic and mechanical systems printed onto flexible substrates

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