Defining the value of injection current and effective electrical contact area for egain-based molecular tunneling junctions

Felice C. Simeone, Hyo Jae Yoon, Martin M. Thuo, Jabulani R. Barber, Barbara Smith, George M. Whitesides

Research output: Contribution to journalArticle

111 Citations (Scopus)

Abstract

Analysis of rates of tunneling across self-assembled monolayers (SAMs) of n-alkanethiolates SCn (with n = number of carbon atoms) incorporated in junctions having structure AgTS-SAM//Ga2O 3/EGaIn leads to a value for the injection tunnel current density J0 (i.e., the current flowing through an ideal junction with n = 0) of 103.6±0.3 A·cm-2 (V = +0.5 V). This estimation of J0 does not involve an extrapolation in length, because it was possible to measure current densities across SAMs over the range of lengths n = 1-18. This value of J0 is estimated under the assumption that values of the geometrical contact area equal the values of the effective electrical contact area. Detailed experimental analysis, however, indicates that the roughness of the Ga2O3 layer, and that of the Ag TS-SAM, determine values of the effective electrical contact area that are ∼10-4 the corresponding values of the geometrical contact area. Conversion of the values of geometrical contact area into the corresponding values of effective electrical contact area results in J 0(+0.5 V) = 107.6±0.8 A·cm-2, which is compatible with values reported for junctions using top-electrodes of evaporated Au, and graphene, and also comparable with values of J0 estimated from tunneling through single molecules. For these EGaIn-based junctions, the value of the tunneling decay factor β (β = 0.75 ± 0.02 Å-1; β = 0.92 ± 0.02 nC-1) falls within the consensus range across different types of junctions (β = 0.73-0.89 Å-1; β = 0.9-1.1 nC-1). A comparison of the characteristics of conical Ga2O3/EGaIn tips with the characteristics of other top-electrodes suggests that the EGaIn-based electrodes provide a particularly attractive technology for physical-organic studies of charge transport across SAMs.

Original languageEnglish (US)
Pages (from-to)18131-18144
Number of pages14
JournalJournal of the American Chemical Society
Volume135
Issue number48
DOIs
StatePublished - Dec 4 2013
Externally publishedYes

Fingerprint

Self assembled monolayers
Electrodes
Injections
Graphite
Current density
Carbon
Technology
Extrapolation
Graphene
Charge transfer
Tunnels
Surface roughness
Atoms
Molecules

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Defining the value of injection current and effective electrical contact area for egain-based molecular tunneling junctions. / Simeone, Felice C.; Yoon, Hyo Jae; Thuo, Martin M.; Barber, Jabulani R.; Smith, Barbara; Whitesides, George M.

In: Journal of the American Chemical Society, Vol. 135, No. 48, 04.12.2013, p. 18131-18144.

Research output: Contribution to journalArticle

Simeone, Felice C. ; Yoon, Hyo Jae ; Thuo, Martin M. ; Barber, Jabulani R. ; Smith, Barbara ; Whitesides, George M. / Defining the value of injection current and effective electrical contact area for egain-based molecular tunneling junctions. In: Journal of the American Chemical Society. 2013 ; Vol. 135, No. 48. pp. 18131-18144.
@article{3dfedf75b5b84110a91f0c40c5fc0c03,
title = "Defining the value of injection current and effective electrical contact area for egain-based molecular tunneling junctions",
abstract = "Analysis of rates of tunneling across self-assembled monolayers (SAMs) of n-alkanethiolates SCn (with n = number of carbon atoms) incorporated in junctions having structure AgTS-SAM//Ga2O 3/EGaIn leads to a value for the injection tunnel current density J0 (i.e., the current flowing through an ideal junction with n = 0) of 103.6±0.3 A·cm-2 (V = +0.5 V). This estimation of J0 does not involve an extrapolation in length, because it was possible to measure current densities across SAMs over the range of lengths n = 1-18. This value of J0 is estimated under the assumption that values of the geometrical contact area equal the values of the effective electrical contact area. Detailed experimental analysis, however, indicates that the roughness of the Ga2O3 layer, and that of the Ag TS-SAM, determine values of the effective electrical contact area that are ∼10-4 the corresponding values of the geometrical contact area. Conversion of the values of geometrical contact area into the corresponding values of effective electrical contact area results in J 0(+0.5 V) = 107.6±0.8 A·cm-2, which is compatible with values reported for junctions using top-electrodes of evaporated Au, and graphene, and also comparable with values of J0 estimated from tunneling through single molecules. For these EGaIn-based junctions, the value of the tunneling decay factor β (β = 0.75 ± 0.02 {\AA}-1; β = 0.92 ± 0.02 nC-1) falls within the consensus range across different types of junctions (β = 0.73-0.89 {\AA}-1; β = 0.9-1.1 nC-1). A comparison of the characteristics of conical Ga2O3/EGaIn tips with the characteristics of other top-electrodes suggests that the EGaIn-based electrodes provide a particularly attractive technology for physical-organic studies of charge transport across SAMs.",
author = "Simeone, {Felice C.} and Yoon, {Hyo Jae} and Thuo, {Martin M.} and Barber, {Jabulani R.} and Barbara Smith and Whitesides, {George M.}",
year = "2013",
month = "12",
day = "4",
doi = "10.1021/ja408652h",
language = "English (US)",
volume = "135",
pages = "18131--18144",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "48",

}

TY - JOUR

T1 - Defining the value of injection current and effective electrical contact area for egain-based molecular tunneling junctions

AU - Simeone, Felice C.

AU - Yoon, Hyo Jae

AU - Thuo, Martin M.

AU - Barber, Jabulani R.

AU - Smith, Barbara

AU - Whitesides, George M.

PY - 2013/12/4

Y1 - 2013/12/4

N2 - Analysis of rates of tunneling across self-assembled monolayers (SAMs) of n-alkanethiolates SCn (with n = number of carbon atoms) incorporated in junctions having structure AgTS-SAM//Ga2O 3/EGaIn leads to a value for the injection tunnel current density J0 (i.e., the current flowing through an ideal junction with n = 0) of 103.6±0.3 A·cm-2 (V = +0.5 V). This estimation of J0 does not involve an extrapolation in length, because it was possible to measure current densities across SAMs over the range of lengths n = 1-18. This value of J0 is estimated under the assumption that values of the geometrical contact area equal the values of the effective electrical contact area. Detailed experimental analysis, however, indicates that the roughness of the Ga2O3 layer, and that of the Ag TS-SAM, determine values of the effective electrical contact area that are ∼10-4 the corresponding values of the geometrical contact area. Conversion of the values of geometrical contact area into the corresponding values of effective electrical contact area results in J 0(+0.5 V) = 107.6±0.8 A·cm-2, which is compatible with values reported for junctions using top-electrodes of evaporated Au, and graphene, and also comparable with values of J0 estimated from tunneling through single molecules. For these EGaIn-based junctions, the value of the tunneling decay factor β (β = 0.75 ± 0.02 Å-1; β = 0.92 ± 0.02 nC-1) falls within the consensus range across different types of junctions (β = 0.73-0.89 Å-1; β = 0.9-1.1 nC-1). A comparison of the characteristics of conical Ga2O3/EGaIn tips with the characteristics of other top-electrodes suggests that the EGaIn-based electrodes provide a particularly attractive technology for physical-organic studies of charge transport across SAMs.

AB - Analysis of rates of tunneling across self-assembled monolayers (SAMs) of n-alkanethiolates SCn (with n = number of carbon atoms) incorporated in junctions having structure AgTS-SAM//Ga2O 3/EGaIn leads to a value for the injection tunnel current density J0 (i.e., the current flowing through an ideal junction with n = 0) of 103.6±0.3 A·cm-2 (V = +0.5 V). This estimation of J0 does not involve an extrapolation in length, because it was possible to measure current densities across SAMs over the range of lengths n = 1-18. This value of J0 is estimated under the assumption that values of the geometrical contact area equal the values of the effective electrical contact area. Detailed experimental analysis, however, indicates that the roughness of the Ga2O3 layer, and that of the Ag TS-SAM, determine values of the effective electrical contact area that are ∼10-4 the corresponding values of the geometrical contact area. Conversion of the values of geometrical contact area into the corresponding values of effective electrical contact area results in J 0(+0.5 V) = 107.6±0.8 A·cm-2, which is compatible with values reported for junctions using top-electrodes of evaporated Au, and graphene, and also comparable with values of J0 estimated from tunneling through single molecules. For these EGaIn-based junctions, the value of the tunneling decay factor β (β = 0.75 ± 0.02 Å-1; β = 0.92 ± 0.02 nC-1) falls within the consensus range across different types of junctions (β = 0.73-0.89 Å-1; β = 0.9-1.1 nC-1). A comparison of the characteristics of conical Ga2O3/EGaIn tips with the characteristics of other top-electrodes suggests that the EGaIn-based electrodes provide a particularly attractive technology for physical-organic studies of charge transport across SAMs.

UR - http://www.scopus.com/inward/record.url?scp=84889836470&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84889836470&partnerID=8YFLogxK

U2 - 10.1021/ja408652h

DO - 10.1021/ja408652h

M3 - Article

VL - 135

SP - 18131

EP - 18144

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 48

ER -