Influence of self-assembled monolayer dielectrics on the morphology and performance of α,ω-dihexylquaterthiophene in thin film transistors

Novák, Michael; Schmaltz, Thomas; Faber, Hendrik; Halik, Marcus

doi:10.1063/1.3560454

Cited by 37 publications

(29 citation statements)

References 26 publications

(31 reference statements)

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“…Two types of organic molecules were investigated, namely hexamethyldisilazane (HMDS) and phosphonohexadecanoic acid (PHDA) [ Figure a]. Both SAM molecules are known to form dense and conformal self‐assembled monolayers on solid surfaces with suitable chemistry and have been used extensively as surface passivation agents, surface energy modifiers, and ultrathin gate dielectrics in low‐voltage organic transistors . Importantly, both SAMs can be processed from solution or vapor phase at room temperature onto large‐area substrates and the resulting monolayers are known to exhibit excellent thermal stability making them compatible with the device process flowchart employed in this work .…”

Section: Hybrid Resonant Tunneling Devicesmentioning

confidence: 99%

Signatures of Quantized Energy States in Solution‐Processed Ultrathin Layers of Metal‐Oxide Semiconductors and Their Devices

Labram

Lin

et al. 2015

Adv Funct Materials

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Physical phenomena such as energy quantization have to-date been overlooked in solutionprocessed inorganic semiconducting layers, owing to heterogeneity in layer thickness uniformity unlike some of their vacuum-deposited counterparts. Recent reports of the growth of uniform, ultra-thin (<5 nm) metal-oxide semiconductors from solution, however, have potentially opened the door to such phenomena manifesting themselves. Here, we develop a theoretical framework for energy quantization in inorganic semiconductor layers with appreciable surface roughness, as compared to the mean layer thickness, and present experimental evidence of the existence of quantized energy states in spin-cast layers of zinc oxide (ZnO). As-grown ZnO layers are found to be remarkably continuous and uniform with controllable thicknesses in the range 2-20 nm and exhibit a characteristic widening of the energy band gap with reducing thickness in agreement with theoretical predictions. Using sequentially spin-casted layers of ZnO as the bulk semiconductor and quantum well materials, and gallium oxide or organic self-assembled monolayers as the barrier materials, we demonstrate two terminal electronic devices the current-voltage characteristics of which resemble closely those of double-barrier resonant-tunneling diodes. As-fabricated alloxide/hybrid devices exhibit a characteristic negative-differential conductance region with peak-to-valley ratios in the range 2 -7.

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Section: Hybrid Resonant Tunneling Devicesmentioning

confidence: 99%

Signatures of Quantized Energy States in Solution‐Processed Ultrathin Layers of Metal‐Oxide Semiconductors and Their Devices

Labram

Lin

et al. 2015

Adv Funct Materials

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“…After the lift-off in acetone, an oxygen plasma treatment was performed in a plasma chamber (Diener Electronic Pico, 200 W) for 5 min to generate a dense aluminium oxide layer of around 3.6 nm thickness. 43 This AlO x film serves as inorganic part of the hybrid dielectric and as anchor surface for the phosphonic acids. The self-assembly of phosphonic acids on the surface was carried out directly after the plasma treatment by immersing the substrates into dilute solutions of C 60 C 18 -PA or mixed solutions of alkyl-PA (C 6 -PA, C 10 -PA, C 14 -PA, C 16 -PA or C 18 -PA) and C 60 C 18 -PA in a 1 : 1 molar ratio with a overall concentration of 0.005 mM in 2-propanol.…”

Section: Tft Fabricationmentioning

confidence: 99%

Tuning the molecular order of C₆₀-based self-assembled monolayers in field-effect transistors

Schmaltz¹,

Khassanov²,

Steinrück

et al. 2014

Nanoscale

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The control of order in organic semiconductor systems is crucial to achieve desired properties in electronic devices. We have studied the order in fullerene functionalized self-assembled monolayers by mixing the active molecules with supporting alkyl phosphonic acids of different chain length. By adjusting the length of the molecules, structural modifications of the alignment of the C 60 head groups within the SAM can be tuned in a controlled way. These changes on the sub-nanometre scale were analysed by grazing incidence X-ray diffraction and X-ray reflectivity. To study the electron transport properties across these layers, self-assembled monolayer field-effect transistors (SAMFETs) were fabricated containing only the single fullerene monolayer as semiconductor. Electrical measurements revealed that a high 2D crystalline order is not the only important aspect. If the fullerene head groups are too confined by the supporting alkyl phosphonic acid molecules, defects in the crystalline C 60 film, such as grain boundaries, start to strongly limit the charge transport properties. By close interpretation of the results of structural investigations and correlating them to the results of electrical characterization, an optimum chain length of the supporting alkyl phosphonic acids in the range of C 10 was determined. With this study we show that minor changes in the order on the sub-nanometre scale, can strongly influence electronic properties of functional self-assembled monolayers.

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“…[ 18 ] The slightly reduced "overall performance" of transistors compared to devices with the same semiconductor but on other SAMs [ 16 ] can be attributed to the surface energy of the SAM which infl uences the semiconductor orientation and morphology at the interface which in turn directly infl uences the performance. [ 19,20 ] Additionally, the decrease of the absolute threshold voltage V th for the doped samples can be seen in Figure 3 c. V th of the reference sample is −2.91 V whereas the doping with potassium shifts it to −2.78 V, for lithium to −2.70 V, and for sodium to −2.68 V.…”

Section: Doi: 101002/adma201503911mentioning

confidence: 93%

Improving the Performance of Organic Thin‐Film Transistors by Ion Doping of Ethylene‐Glycol‐Based Self‐Assembled Monolayer Hybrid Dielectrics

Dietrich

Scheiner²,

Portilla³

et al. 2015

Advanced Materials

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Tuning the electrostatics of ethylene-glycol-based self-assembled monolayers (SAMs) by doping with ions is shown. Molecular dynamics simulations unravel binding mechanisms and predict dipole strengths of the doped layers. Additionally, by applying such layers as dielectrics in organic thin-film transistors, the incorporated ions are proven to enhance device performance by lowering the threshold voltage and increasing conductivity.

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Influence of self-assembled monolayer dielectrics on the morphology and performance of α,ω-dihexylquaterthiophene in thin film transistors

Cited by 37 publications

References 26 publications

Signatures of Quantized Energy States in Solution‐Processed Ultrathin Layers of Metal‐Oxide Semiconductors and Their Devices

Signatures of Quantized Energy States in Solution‐Processed Ultrathin Layers of Metal‐Oxide Semiconductors and Their Devices

Tuning the molecular order of C₆₀-based self-assembled monolayers in field-effect transistors

Improving the Performance of Organic Thin‐Film Transistors by Ion Doping of Ethylene‐Glycol‐Based Self‐Assembled Monolayer Hybrid Dielectrics

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Influence of self-assembled monolayer dielectrics on the morphology and performance of α,ω-dihexylquaterthiophene in thin film transistors

Cited by 37 publications

References 26 publications

Signatures of Quantized Energy States in Solution‐Processed Ultrathin Layers of Metal‐Oxide Semiconductors and Their Devices

Signatures of Quantized Energy States in Solution‐Processed Ultrathin Layers of Metal‐Oxide Semiconductors and Their Devices

Tuning the molecular order of C60-based self-assembled monolayers in field-effect transistors

Improving the Performance of Organic Thin‐Film Transistors by Ion Doping of Ethylene‐Glycol‐Based Self‐Assembled Monolayer Hybrid Dielectrics

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Tuning the molecular order of C₆₀-based self-assembled monolayers in field-effect transistors