Ballistic emission spectroscopy and imaging of a buried metal∕organic interface

Troadec, Cedric; Kunardi, Linda; Chandrasekhar, N.

doi:10.1063/1.1862789

Cited by 22 publications

(16 citation statements)

References 11 publications

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“…Pd/ GaAs diodes grown on epi-GaAs sometimes showed stable tunnel current in air, but a BEEM signal was never detected. 26 We did try adding a capping layer consisting of a C16MT molecular layer to Pd, Ag, and Au/ Ag/ GaAs diodes, but this also failed to improve the diode quality or allow BEEM signal detection. Corresponding STM and BEEM images for Au/ Pd/ GaAs diodes, as a function of the type and presence of a molecular layer, are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Au ∕ Ag and Au∕Pd molecular contacts to GaAs

Ahktari-Zavareh

Kavanagh

et al. 2008

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The hot electron transport through Au/ Pd or Au/ Ag/molecular layer/n-GaAs diodes has been studied by using ballistic electron emission microscopy ͑BEEM͒. The monolayers consisted of either octanedithiol ͑HS -͑CH 2 ͒ 8 -SH͒ or hexadecanethiol ͑HS -͑CH 2 ͒ 15 -CH 3 ͒ linear alkane chains and were deposited from ethanol solutions onto molecular beam epitaxially grown GaAs ͑001͒ surfaces. The metals were electron-beam evaporated onto the molecular layer. Similar to previous results for Au diodes, Au/ Pd metallization onto an octanedithiol monolayer resulted in a large reduction in the BEEM signal, compared to Au and Au/ Pd reference diodes ͑without monolayers͒. However, unlike Au/octanedithiol diodes, the BEEM signal was stronger and the threshold was found to be 1.2 eV instead of 1.4 eV. We attribute this to ballistic electron transmission rather than to the photonic signal that we previously reported for Au/octanedithiol. In comparison, the Au/ Pd/hexadecanethiol diodes showed little change from the reference Au/ Pd diodes, suggesting monolayer disruption by interdiffusion of Pd or Au through the molecules to the interface. Ag/ GaAs or Au/ Ag/ GaAs diodes, with or without a molecular layer, did not result in reliable tunneling, likely the result of a tip-induced reaction. The octanedithiol layer on GaAs provides a free thiol group for bonding with the top metal contact, minimizing Au or Pd penetration and the displacement of the molecule-GaAs thiol bond but not completely eliminating these effects in the case of Pd.

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Section: Resultsmentioning

confidence: 99%

Au ∕ Ag and Au∕Pd molecular contacts to GaAs

Ahktari-Zavareh

Kavanagh

et al. 2008

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…An analysis of the current flowing through the semiconductor allows one to obtain information on the interfacial energy barrier. This technique was first applied to the study of the energy barrier at metal/inorganic semiconductor interface 14,15 , and only recently it has been applied to metal/ molecule systems 16,17 . Here we perform ballistic electron emission spectroscopy in a solid-state device by replacing the electron injection from the scanning tunnelling microscope tip with a large-area tunnel barrier.…”

Section: Resultsmentioning

confidence: 99%

Determination of energy level alignment at metal/molecule interfaces by in-device electrical spectroscopy

et al. 2014

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The energetics of metal/molecular semiconductor interfaces plays a fundamental role in organic electronics, determining the performance of very diverse devices. So far, information about the energy level alignment has been most commonly gained by spectroscopy techniques that typically require experimental conditions far from the real device operation. Here we demonstrate that a simple three-terminal device allows the acquisition of spectroscopic information about the metal/molecule energy alignment in real operative condition. As a proof of principle, we employ the proposed device to measure the energy barrier height between different clean metals and C 60 molecules and we recover typical results from photoemission spectroscopy. The device is designed to inject a hot electron current directly into the molecular level devoted to charge transport, disentangling the contributions of both the interface and the bulk to the device total resistance, with important implications for spintronics and low-temperature physics.

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“…This is also found in the literature. 14,15 Further, one can clearly see that with decreasing temperature, the onset is significantly shifted to higher values. A detailed data analysis shows that the Schottky barrier increases approximately linearly from 1.2 eV at T=300 K to a value of 1.5 eV at T=10 K. This can be seen best in Fig.…”

mentioning

confidence: 90%

“…As one can see from the literature, [14][15][16] BEEM is also a valuable technique to study interfaces between metals and organic films. In this letter, we use BEEM to investigate the metal/organic interface between gold and molecular beam epitaxial ͑MBE͒ grown films of titanylphthalocyanine ͑TiOPc͒.…”

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confidence: 99%

Ballistic electron transport through titanylphthalocyanine films

Özcan

Smoliner

Andrews

et al. 2007

Applied Physics Letters

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In this letter, Au/tanylphthalocyanine/GaAs diodes incorporating ultrathin films of the archetypal organic semiconductor titanylphthalocyanine were investigated by ballistic electron emission microscopy (BEEM)/spectroscopy. The presence of the organic semiconductor increases the BEEM threshold voltage compared to reference Au∕GaAs diodes. The Schottky barrier heights were measured for various temperatures and show an approximately linear increase from 1.2eV at room temperature to 1.5eV at T=10K.

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Ballistic emission spectroscopy and imaging of a buried metal∕organic interface

Cited by 22 publications

References 11 publications

Au ∕ Ag and Au∕Pd molecular contacts to GaAs

Au ∕ Ag and Au∕Pd molecular contacts to GaAs

Determination of energy level alignment at metal/molecule interfaces by in-device electrical spectroscopy

Ballistic electron transport through titanylphthalocyanine films

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