Metal-free molecular junctions on ITO via amino-silane binding—towards optoelectronic molecular junctions

Sergani, Shlomi; Furmansky, Yulia; Visoly‐Fisher, Iris

doi:10.1088/0957-4484/24/45/455204

Cited by 7 publications

(9 citation statements)

References 50 publications

(63 reference statements)

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“…The most critical step in the junction fabrication process is often considered to be step iii as the relative fragile molecular structure may be altered or damaged during the fabrication of the top electrode. [2,3,6] Therefore, large-area molecular junctions have been fabricated with protective layers (PLs) on top of the monolayer (such as, graphene [92,[97][98][99] and derivatives thereof, [100] electron-beam deposited carbon (eC), [101,102] carbon paint, [103] GaO x in EGaIn junctions, [104] or conductive polymers [105][106][107][108] ), which, in principle, provide stability and protect the monolayer during fabrication of the top-electrode. In reality the situation is more complicated as the PL adds complexity since additional SAM-PL and PL-top electrode interfaces have to be considered.…”

Section: Large-area Molecular Junctionsmentioning

confidence: 99%

The Unusual Dielectric Response of Large Area Molecular Tunnel Junctions Probed with Impedance Spectroscopy

Chen

Nijhuis

2021

Adv Elect Materials

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workings of charge transport in exquisite detail in areas including molecular plasmonics, [9] spintronics, [10,11] bioelectronics, [12] sensing, [13] catalysis, [14,15] energy storage, [12,16] memory, [17][18][19] and flexible electronics. [2,3,[20][21][22] Control over the dielectric behavior of nanoscale systems is important for a wide range of applications including supercapacitors, [23] organic field effect transistors (OFETs), [24][25][26][27] flexible and stretchable electronics, [25,28] optoelectronics, [29] and memory. [30] For example, for OFETs, it is important to develop gate materials with high dielectric constants yet with low leakage (via tunneling) currents. [24,25] In principle, molecular junctions are interesting because they allow us to study the dielectric properties of materials at the molecular length scale, but their dielectric behavior remains, to date, virtually unexplored despite promising features. [31][32][33][34] For instance, it has been predicted that, due to their well-organized nature, self-assembled monolayers (SAMs) can have very high relative dielectric constants ε r of ≈20, [32] while usually bulk organic materials have values of ε r in the range of 2-4. [35,36] Theoretically it has been shown that ε r can increase with the thickness of SAMs helping to avoid the adverse decrease of the capacitance in OFETSs with increasing gate dielectric thickness [26,31,34,35] which, in turn, can be used to reduce leakage currents. The dielectric behavior of SAMs are also important to modulate work functions, [37][38][39][40] or to reduceThe dielectric behavior of organic materials at molecular dimensions can be vastly different than their bulk counterparts and therefore it is important to investigate and control the dielectric response of molecular-scale materials for a large variety of applications. Large-area molecular junctions are explored to study the charge transport mechanisms with unprecedented detail and to demonstrate novel functionalities. Therefore, large-area molecular junctions are, in principle, a promising platform to study the dielectric effects at the molecular scale. This review summarizes recent progress on the measurements and understanding of the dielectric behavior of molecular systems and how they behave differently from their bulk properties. This review introduces, briefly, the concepts of impedance spectroscopy (IS) and how this technique can be applied to study the dielectric response of solid-state large-area molecular junctions. This analysis gives new insights in the factors that determine the dielectric constant of monolayers (including collective electrostatic effects and how the dielectric constant increases with monolayer thickness), how IS gives new insights into the role of defects, and the factors that contribute to the molecule-electrode contact resistance. This review ends with an outlook highlighting interesting future directions.

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Section: Large-area Molecular Junctionsmentioning

confidence: 99%

The Unusual Dielectric Response of Large Area Molecular Tunnel Junctions Probed with Impedance Spectroscopy

Chen

Nijhuis

2021

Adv Elect Materials

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“…[ 18,22 ] Finally, top contacts were evaporated through a shadow mask. In principle, this last patterning step can also be done with CMOS-compatible lithography, [ 10,12,13 ] but with our facility a shadow-mask was more convenient. As poor adhesion between the evaporated metal and the insulator's inner wall could cause dis-connects at the top rim, [ 13 ] we used a rather thick Pb layer, to fi ll-up the wells (Figure 1 a.IV).…”

Section: Full Papersmentioning

confidence: 99%

“…Defects in rectifying junctions can increase the conductance by orders of magnitudes, compared to a defect‐free junction and, thus, their relative contribution is not proportional to their fractional area and is expected to increase for smaller junctions . Leakage through surrounding insulators scales with the perimeter length and is, therefore, also more pronounced, the smaller the contact area is. Thus, one way to test for transport artifacts is to compare the current densities across junctions of varying contact areas .…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Reproducible, Integration‐Compatible Hybrid Molecular/Si Electronics

Lovrinčić

Kraynis

et al. 2014

Small

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Reproducible molecular junctions can be integrated within standard CMOS technology. Metal-molecule-semiconductor junctions are fabricated by direct Si-C binding of hexadecane or methyl-styrene onto oxide-free H-Si(111) surfaces, with the lateral size of the junctions defined by an etched SiO2 well and with evaporated Pb as the top contact. The current density, J, is highly reproducible with a standard deviation in log(J) of 0.2 over a junction diameter change from 3 to 100 μm. Reproducibility over such a large range indicates that transport is truly across the molecules and does not result from artifacts like edge effects or defects in the molecular monolayer. Device fabrication is tested for two n-Si doping levels. With highly doped Si, transport is dominated by tunneling and reveals sharp conductance onsets at room temperature. Using the temperature dependence of current across medium-doped n-Si, the molecular tunneling barrier can be separated from the Si-Schottky one, which is a 0.47 eV, in agreement with the molecular-modified surface dipole and quite different from the bare Si-H junction. This indicates that Pb evaporation does not cause significant chemical changes to the molecules. The ability to manufacture reliable devices constitutes important progress toward possible future hybrid Si-based molecular electronics.

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“…With the dramatic scaling of silicon devices to the sub-20 nm length scale, it is becoming critical to probe transport properties of complex silicon-based nanoscale structures, such as silicon clusters, nanowires and silicene 2D layers. 1 – 4 Efforts in molecular electronics have demonstrated the use of silicon surfaces as electrodes 5 – 9 and amino-silanes as chemical binding groups to the electrodes. 10 , 11 Moreover, investigation on cyclohexasilane 12 has shown that conformations affect the molecule's electronic structure and another study on [2,2,2]bicyclic carbosilane systems 13 has suggested that different disilanylene bridges in the cage compounds do not act as parallel resistors.…”

Section: Introductionmentioning

confidence: 99%

Conformations of cyclopentasilane stereoisomers control molecular junction conductance

Garner

Shangguan

et al. 2016

Chem. Sci.

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Metal-free molecular junctions on ITO via amino-silane binding—towards optoelectronic molecular junctions

Cited by 7 publications

References 50 publications

The Unusual Dielectric Response of Large Area Molecular Tunnel Junctions Probed with Impedance Spectroscopy

The Unusual Dielectric Response of Large Area Molecular Tunnel Junctions Probed with Impedance Spectroscopy

Fabrication of Reproducible, Integration‐Compatible Hybrid Molecular/Si Electronics

Conformations of cyclopentasilane stereoisomers control molecular junction conductance

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