Temperature-Dependent Electronic Transport through Alkyl Chain Monolayers:  Evidence for a Molecular Signature

Salomon, Adi; Shpaisman, Hagay; Seitz, Oliver; Boecking, and Till; Cahen, David

doi:10.1021/jp710985b

Cited by 32 publications

(63 citation statements)

References 56 publications

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“…Only at higher forward bias do the currents vary according to the thickness of the insulator, i.e., the molecular layer width here. Such length-independence of current at low forward bias was observed for several moderately-doped n-type MOMS junctions with n-Si [29,56,88,134,135,138,139] and n-GaAs, [35,36,140] contacted with medium-high work-function metals such as Hg.…”

Section: Semiconductor Versus Insulator-limited Transportmentioning

confidence: 53%

“…Furthermore, the longer the molecule is, the more pronounced is the metal-like temperature effect. [138] These observations all point to the monolayer as the origin of this temperature dependence and the question is how?…”

Section: Quasi-metallic Temperature Behavior For Monolayer-limited Cumentioning

confidence: 99%

“…also Refs. [20,29,56,97,138]). This difference can be explained by minor changes in interface electrostatics, e.g., a minute amount of residual chemicals can increase the Si work function and drive the MOMS from inversion (Fig.…”

Section: Transition From Minority To Majority Carrier-dominated Transmentioning

confidence: 99%

“…7a, p-SiÀC 18 /Hg) only ''metal-like'' behavior is found. [138] In contrast, n-Si MOMS show thermally activated (semiconductor-like) behavior at reverse and up to $0.6 V forward bias where the curves at different temperatures (isotherms) cross. The crossing voltage in Figure 7b is very close to that where the J-V curves become length-dependent in Figure 5a, namely, where transport changes from semiconductorto insulator-dependent.…”

Section: Quasi-metallic Temperature Behavior For Monolayer-limited Cumentioning

confidence: 99%

“…[177] For through-space tunneling this implies a narrower barrier and, thus, an exponentially higher current. [138] Increasing temperature also increases the probability for gauche defects and general disorder (''fluidity'') in the monolayer, [178] which affect electrical transport [179] and such disorder will scatter or trap the tunneling charges. Differences in temperature dependences of Si-MOMS and MIM junctions may well be related to how and how strongly the molecules are bound to Au as compared to Si.…”

Section: Quasi-metallic Temperature Behavior For Monolayer-limited Cumentioning

confidence: 99%

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Molecules on Si: Electronics with Chemistry

et al. 2009

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Basic scientific interest in using a semiconducting electrode in molecule‐based electronics arises from the rich electrostatic landscape presented by semiconductor interfaces. Technological interest rests on the promise that combining existing semiconductor (primarily Si) electronics with (mostly organic) molecules will result in a whole that is larger than the sum of its parts. Such a hybrid approach appears presently particularly relevant for sensors and photovoltaics. Semiconductors, especially Si, present an important experimental test‐bed for assessing electronic transport behavior of molecules, because they allow varying the critical interface energetics without, to a first approximation, altering the interfacial chemistry. To investigate semiconductor‐molecule electronics we need reproducible, high‐yield preparations of samples that allow reliable and reproducible data collection. Only in that way can we explore how the molecule/electrode interfaces affect or even dictate charge transport, which may then provide a basis for models with predictive power.To consider these issues and questions we will, in this Progress Report, review junctions based on direct bonding of molecules to oxide‐free Si. describe the possible charge transport mechanisms across such interfaces and evaluate in how far they can be quantified. investigate to what extent imperfections in the monolayer are important for transport across the monolayer. revisit the concept of energy levels in such hybrid systems.

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Section: Semiconductor Versus Insulator-limited Transportmentioning

confidence: 53%

Section: Quasi-metallic Temperature Behavior For Monolayer-limited Cumentioning

confidence: 99%

Section: Transition From Minority To Majority Carrier-dominated Transmentioning

confidence: 99%

Section: Quasi-metallic Temperature Behavior For Monolayer-limited Cumentioning

confidence: 99%

Section: Quasi-metallic Temperature Behavior For Monolayer-limited Cumentioning

confidence: 99%

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Molecules on Si: Electronics with Chemistry

et al. 2009

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Doping Molecular Monolayers: Effects on Electrical Transport Through Alkyl Chains on Silicon

Seitz

Vilan

Cohen

et al. 2008

Adv Funct Materials

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Abstractn‐Si/CnH2n + 1/Hg junctions (n = 12, 14, 16 and 18) can be prepared with sufficient quality to assure that the transport characteristics are not anymore dominated by defects in the molecular monolayers. With such organic monolayers we can, using electron, UV and X‐ray irradiation, alter the charge transport through the molecular junctions on n‐ as well as on p‐type Si. Remarkably, the quality of the self‐assembled molecular monolayers following irradiation remains sufficiently high to provide the same very good protection of Si from oxidation in ambient atmosphere as provided by the pristine films. Combining spectroscopic (UV photoemission spectroscopy (UPS), X‐ray photoelectron spectroscopy (XPS), Auger, near edge‐X‐ray absorption fine structure (NEXAFS)) and electrical transport measurements, we show that irradiation induces defects in the alkyl films, most likely CC bonds and CC crosslinks, and that the density of defects can be controlled by irradiation dose. These altered intra‐ and intermolecular bonds introduce new electronic states in the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap of the alkyl chains and, in the process, dope the organic film. We demonstrate an enhancement of 1–2 orders of magnitude in current. This change is clearly distinguishable from the previous observed difference between transport through high quality and defective monolayers. A detailed analysis of the electrical transport at different temperatures shows that the dopants modify the transport mechanism from tunnelling to hopping. This study suggests a way to extend significantly the use of monolayers in molecular electronics.

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Replacing Ag^TSSCH₂‐R with Ag^TSO₂C‐R in EGaIn‐Based Tunneling Junctions Does Not Significantly Change Rates of Charge Transport

et al. 2014

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Abstract:This paper compares rates of charge transport by tunneling across junctions with the structures Ag TS X(CH 2 ) 2n CH 3 //Ga 2 O 3 /EGaIn (n = 1 -8 and X = -SCH 2 -and -O 2 C-); here Ag TS was template-stripped silver, and EGaIn is the eutectic alloy of gallium and indium. Its objective was to compare the tunneling decay coefficient (β, Å -1 ) and the injection current (J 0 , A/cm 2 ) of the junctions comprising SAMs of n-alkanethiolates and n-alkanoates.

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Temperature-Dependent Electronic Transport through Alkyl Chain Monolayers: Evidence for a Molecular Signature

Cited by 32 publications

References 56 publications

Molecules on Si: Electronics with Chemistry

Molecules on Si: Electronics with Chemistry

Doping Molecular Monolayers: Effects on Electrical Transport Through Alkyl Chains on Silicon

Replacing Ag^TSSCH₂‐R with Ag^TSO₂C‐R in EGaIn‐Based Tunneling Junctions Does Not Significantly Change Rates of Charge Transport

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Temperature-Dependent Electronic Transport through Alkyl Chain Monolayers: Evidence for a Molecular Signature

Cited by 32 publications

References 56 publications

Molecules on Si: Electronics with Chemistry

Molecules on Si: Electronics with Chemistry

Doping Molecular Monolayers: Effects on Electrical Transport Through Alkyl Chains on Silicon

Replacing AgTSSCH2‐R with AgTSO2C‐R in EGaIn‐Based Tunneling Junctions Does Not Significantly Change Rates of Charge Transport

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Replacing Ag^TSSCH₂‐R with Ag^TSO₂C‐R in EGaIn‐Based Tunneling Junctions Does Not Significantly Change Rates of Charge Transport