The Experts below are selected from a list of 42279 Experts worldwide ranked by ideXlab platform
Alex K.y. Jen - One of the best experts on this subject based on the ideXlab platform.
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Influence of Self-Assembled Monolayer binding group on graphene transistors
Applied Physics Letters, 2015Co-Authors: Nathan Cernetic, Daniel O Hutchins, Hong Ma, Alex K.y. JenAbstract:Graphene transistors on Self-Assembled Monolayer (SAM) modified dielectric substrates were fabricated and characterized in order to determine the influence SAM binding group has on device properties. It was found that silane based alkyl SAMs had little to no influence in doping graphene transistors, while phosphonic acid based ones caused n-type doping of graphene transistors with a charge neutrality point shift of over 10 V. It was also discovered that alkyl SAM packing density influenced the doping magnitude. Due to substrate surface charge trap quenching, these SAMs independent of binding group enhanced charge mobility of graphene transistors compared to ones on bare oxide substrates.
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solution processed inverted tandem polymer solar cells with Self Assembled Monolayer modified interfacial layers
Applied Physics Letters, 2010Co-Authors: Steven K. Hau, Hin Lap Yip, Kungshih Chen, Jingyu Zou, Alex K.y. JenAbstract:Inverted tandem bulk-heterojunction solar cells with comparable efficiency to single layer devices have been demonstrated by utilizing two thin layers (∼50 nm) of poly-(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester as the active material and a fullerene Self-Assembled Monolayer (C60-SAM) to modify the interfaces between the ZnO buffer layer and the active layer. Single and tandem solar cells without the SAM modification have much lower efficiencies than the ones with modification. The successful demonstrations of inverted tandem devices with SAM modification give promise of further device improvements if active materials with complementary absorption can be used.
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High performance ambient processed inverted polymer solar cells through interfacial modification with a fullerene Self-Assembled Monolayer
Applied Physics Letters, 2008Co-Authors: Steven K. Hau, Hin Lap Yip, Hong Ma, Alex K.y. JenAbstract:The performance of inverted bulk-heterojunction solar cells with zinc oxide nanoparticles as the electron selective contact is compared to those modified with a fullerene Self-Assembled Monolayer (C60-SAM). The devices modified with a C60-SAM show very significant improvement in conversion efficiencies compared to unmodified devices leading to efficiencies as high as 4.9%. This is due to enhanced electronic coupling of the inorganic/organic interface from the C60-SAM leading to improved fill factor and photocurrent. Furthermore, devices fabricated in an inert environment were compared to those fabricated in ambient showing comparable device performance.
Hagen Klauk - One of the best experts on this subject based on the ideXlab platform.
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top gate zno nanowire transistors and integrated circuits with ultrathin Self Assembled Monolayer gate dielectric
Nano Letters, 2011Co-Authors: Daniel Kalblein, Thomas R Weitz, Jens H Bottcher, Frederik Ante, Ute Zschieschang, Klaus Kern, Hagen KlaukAbstract:A novel approach for the fabrication of transistors and circuits based on individual single-crystalline ZnO nanowires synthesized by a low-temperature hydrothermal method is reported. The gate dielectric of these transistors is a Self-Assembled Monolayer that has a thickness of 2 nm and efficiently isolates the ZnO nanowire from the top-gate electrodes. Inverters fabricated on a single ZnO nanowire operate with frequencies up to 1 MHz. Compared with metal-semiconductor field-effect transistors, in which the isolation of the gate electrode from the carrier channel relies solely on the depletion layer in the semiconductor, the Self-Assembled Monolayer dielectric leads to a reduction of the gate current by more than 3 orders of magnitude.
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thermal stability of organic thin film transistors with Self Assembled Monolayer dielectrics
Applied Physics Letters, 2010Co-Authors: Kenjiro Fukuda, Ute Zschieschang, Hagen Klauk, Tomoyuki Yokota, Kazunori Kuribara, Tsuyoshi Sekitani, Takao SomeyaAbstract:We have investigated the annealing effects on 2 V-operation pentacene organic thin-film transistors (TFTs) with Self-Assembled Monolayer-based gate dielectrics. When pentacene TFTs without passivation layers are annealed at 100 °C, the pentacene crystal structure changes to the bulk phase, resulting in an irreversible degradation of electronic performances. This degradation is suppressed by a 2.5-μm-thick passivation layer. The mobility of the encapsulated TFTs decreases by only 12% upon annealing at 140 °C. We have also investigated the bias-stress effect and found the drain current of low-voltage pentacene TFTs annealed at 70 °C decreases by 1% during continuous bias stress for 1 h.
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high performance carbon nanotube field effect transistors with a thin gate dielectric based on a Self Assembled Monolayer
Nano Letters, 2007Co-Authors: Ralf Thomas Weitz, Ute Zschieschang, Hagen Klauk, Franz Effenberger, Marko Burghard, Klaus KernAbstract:Individual single-walled carbon nanotube (SWCNT) field effect transistors (FETs) with a 2 nm thick silane-based organic Self-Assembled Monolayer (SAM) gate dielectric have been manufactured. The FETs exhibit a unique combination of excellent device performance parameters. In particular, they operate with a gate−source voltage of only −1 V and exhibit good saturation, large transconductance, and small hysteresis (≤100 mV), as well as a very low subthreshold swing (60 mV/dec) under ambient conditions. The SAM-based gate dielectric opens the possibility of fabricating transistors operating at low voltages and constitutes a major step toward nanotube-based flexible electronics.
Andreas Hirsch - One of the best experts on this subject based on the ideXlab platform.
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improving the charge transport in Self Assembled Monolayer field effect transistors from theory to devices
Journal of the American Chemical Society, 2013Co-Authors: Christof M Jager, Thomas Schmaltz, Artoem Khassanov, Michael Novak, Alexei Vorobiev, Matthias Hennemann, A Krause, Hanno Dietrich, Dirk Zahn, Andreas HirschAbstract:A three-pronged approach has been used to design rational improvements in Self-Assembled Monolayer field-effect transistors: classical molecular dynamics (MD) simulations to investigate atomistic structure, large-scale quantum mechanical (QM) calculations for electronic properties, and device fabrication and characterization as the ultimate goal. The MD simulations reveal the effect of using two-component Monolayers to achieve intact dielectric insulating layers and a well-defined semiconductor channel. The QM calculations identify improved conduction paths in the Monolayers that consist of an optimum mixing ratio of the components. These results have been used both to confirm the predictions of the calculations and to optimize real devices. Monolayers were characterized with X-ray reflectivity measurements and by electronic characterization of complete devices.
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low voltage p and n type organic Self Assembled Monolayer field effect transistors
Nano Letters, 2011Co-Authors: Michael Novak, Timo Meyerfriedrichsen, Kislon Voitchovsky, Francesco Stellacci, Alexander Ebel, Abdesselam Jedaa, Benito F Vieweg, Guang Yang, Erdmann Spiecker, Andreas HirschAbstract:We report on p- and n-type organic Self-Assembled Monolayer field effect transistors. On the base of quaterthiophene and fullerene units, multifunctional molecules were synthesized, which have the ability to Self-assemble and provide multifunctional Monolayers. The Self-assembly approach, based on phosphonic acids, is very robust and allows the fabrication of functional devices even on larger areas. The p- and n-type transistor devices with only one molecular active layer were demonstrated for transistor channel lengths up to 10 μm. The Monolayer composition is proven by electrical experiments and by high-resolution transmission electron microscopy, electron energy loss spectroscopy, XPS, and AFM experiments. Because of the molecular design and the contribution of isolating alkyl chains to the hybrid dielectric, our devices operate at low supply voltages (−4 V to +4 V), which is a key requirement for practical use and simplifies the integration in standard applications. The Monolayer devices operate in am...
Ute Zschieschang - One of the best experts on this subject based on the ideXlab platform.
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top gate zno nanowire transistors and integrated circuits with ultrathin Self Assembled Monolayer gate dielectric
Nano Letters, 2011Co-Authors: Daniel Kalblein, Thomas R Weitz, Jens H Bottcher, Frederik Ante, Ute Zschieschang, Klaus Kern, Hagen KlaukAbstract:A novel approach for the fabrication of transistors and circuits based on individual single-crystalline ZnO nanowires synthesized by a low-temperature hydrothermal method is reported. The gate dielectric of these transistors is a Self-Assembled Monolayer that has a thickness of 2 nm and efficiently isolates the ZnO nanowire from the top-gate electrodes. Inverters fabricated on a single ZnO nanowire operate with frequencies up to 1 MHz. Compared with metal-semiconductor field-effect transistors, in which the isolation of the gate electrode from the carrier channel relies solely on the depletion layer in the semiconductor, the Self-Assembled Monolayer dielectric leads to a reduction of the gate current by more than 3 orders of magnitude.
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thermal stability of organic thin film transistors with Self Assembled Monolayer dielectrics
Applied Physics Letters, 2010Co-Authors: Kenjiro Fukuda, Ute Zschieschang, Hagen Klauk, Tomoyuki Yokota, Kazunori Kuribara, Tsuyoshi Sekitani, Takao SomeyaAbstract:We have investigated the annealing effects on 2 V-operation pentacene organic thin-film transistors (TFTs) with Self-Assembled Monolayer-based gate dielectrics. When pentacene TFTs without passivation layers are annealed at 100 °C, the pentacene crystal structure changes to the bulk phase, resulting in an irreversible degradation of electronic performances. This degradation is suppressed by a 2.5-μm-thick passivation layer. The mobility of the encapsulated TFTs decreases by only 12% upon annealing at 140 °C. We have also investigated the bias-stress effect and found the drain current of low-voltage pentacene TFTs annealed at 70 °C decreases by 1% during continuous bias stress for 1 h.
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high performance carbon nanotube field effect transistors with a thin gate dielectric based on a Self Assembled Monolayer
Nano Letters, 2007Co-Authors: Ralf Thomas Weitz, Ute Zschieschang, Hagen Klauk, Franz Effenberger, Marko Burghard, Klaus KernAbstract:Individual single-walled carbon nanotube (SWCNT) field effect transistors (FETs) with a 2 nm thick silane-based organic Self-Assembled Monolayer (SAM) gate dielectric have been manufactured. The FETs exhibit a unique combination of excellent device performance parameters. In particular, they operate with a gate−source voltage of only −1 V and exhibit good saturation, large transconductance, and small hysteresis (≤100 mV), as well as a very low subthreshold swing (60 mV/dec) under ambient conditions. The SAM-based gate dielectric opens the possibility of fabricating transistors operating at low voltages and constitutes a major step toward nanotube-based flexible electronics.
Nathan Cernetic - One of the best experts on this subject based on the ideXlab platform.
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enhanced performance of Self Assembled Monolayer field effect transistors with top contact geometry through molecular tailoring heated assembly and thermal annealing
Advanced Functional Materials, 2015Co-Authors: Nathan Cernetic, Tobias Weidner, Joe E Baio, Hao LuAbstract:Low-voltage Self-Assembled Monolayer field-effect transistors (SAMFETs) that operate under an applied bias of less than −3 V and a high hole mobility of 10−2 cm2 V−1 s−1 are reported. A Self-Assembled Monolayer (SAM) with a quaterthiophene semiconducting core and a phosphonic acid binding group is used to fabricate SAMFETs on both high-voltage (AlOx/300 nm SiO2) and low-voltage (HfO2) dielectric platforms. High performance is achieved through enhanced SAM packing density via a heated assembly process and through improved electrical contact between SAM semiconductor and metal electrodes. Enhanced electrical contact is obtained by utilizing a functional methylthio head group combined with thermal annealing post gold source/drain electrode deposition to facilitate the interaction between SAM and electrode.
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Influence of Self-Assembled Monolayer binding group on graphene transistors
Applied Physics Letters, 2015Co-Authors: Nathan Cernetic, Daniel O Hutchins, Hong Ma, Alex K.y. JenAbstract:Graphene transistors on Self-Assembled Monolayer (SAM) modified dielectric substrates were fabricated and characterized in order to determine the influence SAM binding group has on device properties. It was found that silane based alkyl SAMs had little to no influence in doping graphene transistors, while phosphonic acid based ones caused n-type doping of graphene transistors with a charge neutrality point shift of over 10 V. It was also discovered that alkyl SAM packing density influenced the doping magnitude. Due to substrate surface charge trap quenching, these SAMs independent of binding group enhanced charge mobility of graphene transistors compared to ones on bare oxide substrates.
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spin cast Self Assembled Monolayer field effect transistors
Organic Electronics, 2012Co-Authors: Daniel O Hutchins, Nathan Cernetic, Guy Ting, Tobias Weidner, Orb Acton, Joe E Baio, David G CastnerAbstract:Abstract Top-contact Self-Assembled Monolayer field-effect transistors (SAMFETs) were fabricated through both spin-coating and solution assembly of a semiconducting phosphonic acid-based molecule (11-(5⁗-butyl-[2,2′;5′,2″;5″,2‴;5‴,2⁗]quinquethiophen-5-yl)undecylphosphonic acid) (BQT-PA). The field-effect mobilities of both spin-cast and solution Assembled SAMFETs were 1.1–8.0 × 10 −6 cm 2 V −1 s −1 for a wide range of channel lengths (between 12 and 80 μm). The molecular Monolayers were characterized by atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It was found that the BQT-PA Monolayer films exhibit dense surface coverage, bidentate binding, and tilt angles of ∼32° and ∼44° for the thiophene rings and alkyl chain, respectively. These results indicate that rapid throughput of fabricating SAMFETs is possible even by spin-coating.