Increase of Schottky barrier height at GaAs surfaces by carboxylic acid monolayers and multilayers

Tredgold, R.H.; El-Badawy, Z I

doi:10.1088/0022-3727/18/1/013

Cited by 23 publications

(7 citation statements)

References 11 publications

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“…247 The use of Langmuir-Blodgett films also offers the option to add a uniform dipole layer to the semiconductor surface. 248,249 Ideally, the potential drop generated across a uniform layer of dipolar molecules is derivable from the Helmholtz model as 250 …”

Section: A Sbh Modification With Molecular Dipolesmentioning

confidence: 99%

The physics and chemistry of the Schottky barrier height

Tung

2014

Applied Physics Reviews

1,076

479

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The formation of the Schottky barrier height (SBH) is a complex problem because of the dependence of the SBH on the atomic structure of the metal-semiconductor (MS) interface. Existing models of the SBH are too simple to realistically treat the chemistry exhibited at MS interfaces. This article points out, through examination of available experimental and theoretical results, that a comprehensive, quantum-mechanics-based picture of SBH formation can already be constructed, although no simple equations can emerge, which are applicable for all MS interfaces. Important concepts and principles in physics and chemistry that govern the formation of the SBH are described in detail, from which the experimental and theoretical results for individual MS interfaces can be understood. Strategies used and results obtained from recent investigations to systematically modify the SBH are also examined from the perspective of the physical and chemical principles of the MS interface.

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Section: A Sbh Modification With Molecular Dipolesmentioning

confidence: 99%

The physics and chemistry of the Schottky barrier height

Tung

2014

Applied Physics Reviews

1,076

479

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“…They also made Au/GaAs diodes with LB layers of stearic acids (thickness 2.4 nm) and perfluorodecanoic acids (thickness 1.7 nm) and found a similar effect on the barrier height. Therefore, they concluded that the surface density of dipoles is the major parameter rather than the insulator (alkyl chain) length . The major role of interfacial electrostatics is being appreciated more and more in understanding Schottky barriers and especially in the area of organic light emitting diodes (OLEDs) .…”

Section: Introductionmentioning

confidence: 99%

Molecule−Metal Polarization at Rectifying GaAs Interfaces

2003

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Metal/organic monolayer/GaAs junctions, prepared by adsorbing a set of dicarboxylic ligands, with systematic change of ligand substituents, on GaAs, are measured and characterized electrically. The molecules are chemically bound to the semiconductor surface under ambient conditions and form roughly a monolayer (MoL), with average order in the direction perpendicular to the semiconductor surface. This suffices to yield systematic changes in electron affinity and work function of the modified GaAs. Junctions are made by a soft metal deposition method, used here for Au and Al. Experimentally, we find strong molecular effects, reaching differences in current at a given voltage of up to 6 orders of magnitude, depending on the substituent on the molecules making up the monolayer. These and the changes in the effective barrier height of the metal/MoL/ GaAs junctions, extracted by analyses of their current-voltage characteristics, can be explained by electrostatic effects of the molecular layer, rather than by electrodynamic ones (current flow through the molecular film). This can be understood by realizing that the samples are relatively large area devices with extremely narrow (∼1 nm) films of organic molecules, showing only average order, which makes dominance of tunneling effects very unlikely. We show that not only the molecule's electronic and electrical properties but also the way the metals contact the molecules, as well as the doping type of the semiconductor, can determine the direction of the molecular effect. Also the type of metal governs the effect that we identify as being due to interfacial dipoles formed as a result of triple metal/organic molecule/semiconductor interaction.

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“…The experimental procedure followed was in general identical with that described in our 0022-37271851122483 + 05 $02.25 0 1985 The Institute of Physics earlier paper (Tredgold and El-Badawy 1985). However, as we were using polymer films, it was necessary to maintain the sub-phase at a temperature of 30 "C to obtain sufficient fluidity of the spread monolayer and a solvent of ethyl acetate rather than nhexane was employed.…”

Section: Methodsmentioning

confidence: 99%

“…In a recent paper (Tredgold and El-Badawy 1985) we showed that it is possible to increase the efficiency of a solar diode based on GaAs by a factor of 1.24 by the insertion of an insulating Langmuir-Blodgett layer between the semiconductor and the top electrode. The technique of inserting a thin insulating layer into a Schottky solar diode was originated by Stirn and Yeh (1975) and has been studied in the context of GaAs by van Meirhaeghe er a1 (1980,1983).…”

Section: Introductionmentioning

confidence: 99%

GaAs Schottky diodes incorporating Langmuir-Blodgett layers of pre-formed polymers

Tredgold¹,

El-Badawy²

1985

J. Phys. D: Appl. Phys.

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Studies of GaAs photodiodes are described in which insulating layers formed from amphiphilic polymers deposited by the Langmuir-Blodgett technique are incorporated. It is shown that it is possible, by using this technique, to increase the diode efficiency by a substantial amount and to form devices that are stable at temperatures in excess of 200 degrees C and that have considerable mechanical stability.

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Increase of Schottky barrier height at GaAs surfaces by carboxylic acid monolayers and multilayers

Cited by 23 publications

References 11 publications

The physics and chemistry of the Schottky barrier height

The physics and chemistry of the Schottky barrier height

Molecule−Metal Polarization at Rectifying GaAs Interfaces

GaAs Schottky diodes incorporating Langmuir-Blodgett layers of pre-formed polymers

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