Energy Level Alignment and Interfacial Electronic Structures at Organic/Metal and Organic/Organic Interfaces

Ishii, Hisao; Sugiyama, K.; Ito, Eisuke; Seki, Kazuhiko

doi:10.1002/(sici)1521-4095(199906)11:8<605::aid-adma605>3.0.co;2-q

Cited by 2,966 publications

(1,104 citation statements)

References 111 publications

Supporting

Mentioning

1,075

Contrasting

Unclassified

Order By: Relevance

“…[53] To a first approximation, the molecular dipole can be viewed as a constant contribution to C I , which affects the shape of the potential profile C I (x) across the monolayer. The effect of a dipolar layer was reviewed by Ishii et al [125] and the importance of the layer's uniformity has been discussed intensively. [112,126,127] Dipolar monolayers can be bound to a variety of inorganic Figure 3.…”

Section: Molecular Dipolementioning

confidence: 99%

Molecules on Si: Electronics with Chemistry

et al. 2009

View full text Add to dashboard Cite

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.

show abstract

Section: Molecular Dipolementioning

confidence: 99%

Molecules on Si: Electronics with Chemistry

et al. 2009

View full text Add to dashboard Cite

show abstract

“…The formation of Schottky barrier between metal electrode and organic electronics materials has been extensively studied both theoretically [71][72][73] and experimentally [74][75][76][77] in recent years. In addition, the application of SAMs (Self Assembled Monolayers) of π-conjugated thiols for single-molecule electronics have been extensively studied [78].…”

Section: Metal-molecule Interfacementioning

confidence: 99%

Metal−Molecule Schottky Junction Effects in Surface Enhanced Raman Scattering

2010

View full text Add to dashboard Cite

We propose a complementary interpretation of the mechanism responsible for the strong enhancement observed in Surface Enhanced Raman Scattering (SERS). The effect of a strong static local electric field due to Schottky barrier at the metal-molecule junction on SERS is systematically investigated. The study provides a viable explanation to the low repeatability of SERS experiments as well as the Raman peak shifts as observed in SERS and raw Raman spectra. It was found that strong electrostatic build-in field at the metal-molecule junction along specific orientations can result in 2-4 more orders of enhancement in SERS.

show abstract

“…This atomically thin carbon layer provides the additional benefit that its work function can be adjusted by the electric field effect (EFE). Since the band alignment of two different materials is determined by their respective work functions, control over the graphene work function is the key to reducing the contact barriers of graphene top electrode devices 9,10 . Previous scanning probe based studies [11][12][13] reveal that the work function of graphene is in a similar range to that of graphite, ~4.6 eV 14 , and depends sensitively on the number of layers 15,16 .…”

mentioning

confidence: 99%

Tuning the Graphene Work Function by Electric Field Effect

et al. 2009

View full text Add to dashboard Cite

We report variation of the work function for single and bi-layer graphene devices measured by scanning Kelvin probe microscopy (SKPM). Using the electric field effect, the work function of graphene can be adjusted as the gate voltage tunes the Fermi level across the charge neutrality point. Upon biasing the device, the surface potential map obtained by SKPM provides a reliable way to measure the contact resistance of individual electrodes contacting graphene.High conductivity 1,2 and low optical absorption 3,4 make graphene an attractive material for use as a flexible transparent conductive electrode [5][6][7][8] . This atomically thin carbon layer provides the additional benefit that its work function can be adjusted by the electric field effect (EFE). Since the band alignment of two different materials is determined by their respective work functions, control over the graphene work function is the key to reducing the contact barriers of graphene top electrode devices 9, 10 . Previous scanning probe based studies [11][12][13] reveal that the work function of graphene is in a similar range to that of graphite, ~4.6 eV 14 , and depends sensitively on the number of layers 15,16 . However, the active controlling of the graphene work function has yet to be demonstrated.In this study, we apply Scanning Kelvin probe microscope (SKPM) techniques to back-gated graphene devices and demonstrate that the work function can be controlled over a wide range by EFE induced modulation of carrier concentration. SKPM is an atomic force microscope (AFM) based experimental technique that can map the surface potential variation of a sample surface relative to that of metallic tip 17 . The change of work function is ascribed by the Fermi level shift due to the EFE induced carrier doping and is well quantified by the electronic band structure of graphene. On biased graphene devices, SKPM also allows us to accurately measure graphene/metal contact resistances by mapping the surface potential of a device. The wide range of control over the work function demonstrated here suggests graphene as an ideal material for applications where work function optimization is important.Graphene samples were prepared by mechanical exfoliation 18 on Si wafers covered with 300 nm thick SiO 2 and then Cr/Au electrodes (5 nm/30 nm thickness) were fabricated by

show abstract

Energy Level Alignment and Interfacial Electronic Structures at Organic/Metal and Organic/Organic Interfaces

Cited by 2,966 publications

References 111 publications

Molecules on Si: Electronics with Chemistry

Molecules on Si: Electronics with Chemistry

Metal−Molecule Schottky Junction Effects in Surface Enhanced Raman Scattering

Tuning the Graphene Work Function by Electric Field Effect

Contact Info

Product

Resources

About