Spin‐Cast and Patterned Organophosphonate Self‐Assembled Monolayer Dielectrics on Metal‐Oxide‐Activated Si

Acton, Orb; Hutchins, Daniel; Árnadóttir, Líney; Weidner, Tobias; Cernetic, Nathan; Ting, Guy; Kim, Tae Wook; Castner, David G.; Ma, Hong; Jen, Alex K.‐Y.

doi:10.1002/adma.201004762

Cited by 71 publications

(62 citation statements)

References 34 publications

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“…144 We believe this could be attributed to inherently different material/ chemical properties of the phosphonic acid molecule and the aforementioned silane. First, it has been demonstrated that frequently used alkyl-phosphonic acid SAM molecules, which are commonly regarded as highly ordered and densely packed, exhibit an inherent tilt angle of Z 301 much like BQT-PA. 112 The intrinsic tilt angle of the phosphonic acid could result in decreased wave function overlap and inferior charge transport properties relative to the monofunctional chlorosilane molecule which is tilted at 101. Second, the silane based chemistry used by Smits et al, as stated in their supporting information, forms not a true monolayer that may have resulted in increased device performance.…”

Section: Sam-fets Based On Molecular Monolayer Semiconductorsmentioning

confidence: 99%

Multifunctional phosphonic acid self-assembled monolayers on metal oxides as dielectrics, interface modification layers and semiconductors for low-voltage high-performance organic field-effect transistors

Acton

Hutchins

et al. 2012

Phys. Chem. Chem. Phys.

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145

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Insulating and semiconducting molecular phosphonic acid (PA) self-assembled monolayers (SAMs) have been developed for applications in organic field-effect transistors (OFETs) for low-power, low-cost flexible electronics. Multifunctional SAMs on ultrathin metal oxides, such as hafnium oxide and aluminum oxide, are shown to enable (1) low-voltage (sub 2 V) OFETs through dielectric and interface engineering on rigid and plastic substrates, (2) simultaneous one-component modification of source-drain and dielectric surfaces in bottom-contact OFETs, and (3) SAM-FETs based on molecular monolayer semiconductors. The combination of excellent dielectric and interfacial properties results in high-performance OFETs with low-subthreshold slopes down to 75 mV dec(-1), high I(on)/I(off) ratios of 10(5)-10(7), contact resistance down to 700 Ω cm, charge carrier mobilities of 0.1-4.6 cm(2) V(-1) s(-1), and general applicability to solution-processed and vacuum-deposited n-type and p-type organic and polymer semiconductors.

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Section: Sam-fets Based On Molecular Monolayer Semiconductorsmentioning

confidence: 99%

Multifunctional phosphonic acid self-assembled monolayers on metal oxides as dielectrics, interface modification layers and semiconductors for low-voltage high-performance organic field-effect transistors

Acton

Hutchins

et al. 2012

Phys. Chem. Chem. Phys.

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145

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“…This has been shown by our group to deposit a ~2.5nm thick layer of AlOx on substrate surfaces as previously verified by time of flight secondary ion mass spectroscopy (TOF-SIMS) [17]. The PhO-19-PA SAM was prepared on the Si native oxide/AlOx layer via spin coating from a 3 mM solution in chloroform: tetrahydrofuran (THF) (4:1) at 3k RPM for 30 seconds.…”

Section: Methodsmentioning

confidence: 77%

“…One method of obtaining these hybrid structures is through merging inorganic oxides and self-assembled monolayers (SAMs) [17]. This technique has been demonstrated by several groups and has proven to be quite successful, allowing the formation of sufficiently insulative layers that are less than 10 nm in thickness [18–20].…”

Section: Introductionmentioning

confidence: 99%

Solid-state densification of spun-cast self-assembled monolayers for use in ultra-thin hybrid dielectrics

Hutchins

Acton

Weidner

et al. 2012

Applied Surface Science

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Ultra-thin self-assembled monolayer (SAM)-oxide hybrid dielectrics have gained significant interest for their application in low-voltage organic thin film transistors (OTFTs). A [8-(11-phenoxy-undecyloxy)-octyl]phosphonic acid (PhO-19-PA) SAM on ultrathin AlOx (2.5 nm) has been developed to significantly enhance the dielectric performance of inorganic oxides through reduction of leakage current while maintaining similar capacitance to the underlying oxide structure. Rapid processing of this SAM in ambient conditions is achieved by spin coating, however, as-cast monolayer density is not sufficient for dielectric applications. Thermal annealing of a bulk spun-cast PhO-19-PA molecular film is explored as a mechanism for SAM densification. SAM density, or surface coverage, and order are examined as a function of annealing temperature. These SAM characteristics are probed through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure spectroscopy (NEXAFS). It is found that at temperatures sufficient to melt the as-cast bulk molecular film, SAM densification is achieved; leading to a rapid processing technique for high performance SAM-oxide hybrid dielectric systems utilizing a single wet processing step. To demonstrate low-voltage devices based on this hybrid dielectric (with leakage current density of 7.7×10−8 A cm−2 and capacitance density of 0.62 µF cm−2 at 3 V), pentacene thin-film transistors (OTFTs) are fabricated and yield sub 2 V operation and charge carrier mobilites of up to 1.1 cm2 V−1 s−1.

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“…1 Self-assembled monolayers (SAMs) are very promising in this context. 2 For applications where the orientation and structural alignment are crucial for device performance SAMs have been used to improve the performance of electronic devices, 3–9 while protein and DNA SAMs have been adopted as effective sensors in biochips. 10,11 For a SAM-based insulators, perfect order and tight packing of the molecular monolayer is crucial to avoid dielectric breakdown in a device.…”

mentioning

confidence: 99%

High-Throughput Analysis of Molecular Orientation on Surfaces by NEXAFS Imaging of Curved Sample Arrays

et al. 2014

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Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy provides detailed information about the orientation and alignment of thin films. NEXAFS is a synchrotron-based technique—the availability of beam-time per user is typically limited to no more than a few weeks per year. The limited availability is currently a true barrier for using NEXAFS in combinatorial studies of molecular alignment. We have recently demonstrated how large area full field NEXAFS imaging allows users to pursue combinatorial studies of surface chemistry. Now we report an extension of this approach which allows the acquisition of orientation information from a single NEXAFS image. An array with 80 elements (samples), containing eight series of different surface modifications, was mounted on a curved substrate allowing the collection of NEXAFS spectra with a range of orientations with respect to the X-ray beam. Images collected from this array show how hyperspectral NEXAFS data collected from curved surfaces can be used for high-throughput molecular orientation analysis.

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Spin‐Cast and Patterned Organophosphonate Self‐Assembled Monolayer Dielectrics on Metal‐Oxide‐Activated Si

Cited by 71 publications

References 34 publications

Multifunctional phosphonic acid self-assembled monolayers on metal oxides as dielectrics, interface modification layers and semiconductors for low-voltage high-performance organic field-effect transistors

Multifunctional phosphonic acid self-assembled monolayers on metal oxides as dielectrics, interface modification layers and semiconductors for low-voltage high-performance organic field-effect transistors

Solid-state densification of spun-cast self-assembled monolayers for use in ultra-thin hybrid dielectrics

High-Throughput Analysis of Molecular Orientation on Surfaces by NEXAFS Imaging of Curved Sample Arrays

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