Effect of oxygen plasma treatment on reduction of contact resistivity at pentacene/Au interface

Kim, Woong-Kwon; Lee, Jong‐Lam

doi:10.1063/1.2218044

Cited by 40 publications

(36 citation statements)

References 11 publications

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“…To enhance the performance of the BC OFETs, it is essential to reduce the contact resistance by lowering the energy barrier. For this purpose, several methods for treating S/D electrodes have been reported, such as O 2 plasma [8], self-assembled monolayers (SAMs) with a dipole moment [9e11], and a few nanometer thick buffer layer with a transition metal oxide (TMO) [12e14], which can adjust the work function of S/D electrodes. In particular, the use of solutionprocessible TMOs is a favourable method because (i) they can be applied easily to all kinds of metals, (ii) their low process temperature is suitable for flexible or stretchable device fabrication, and (iii) they have deep highest-occupied-molecular-orbital (HOMO) and lowest-unoccupied-molecular-orbital (LUMO) energy levels that are sufficient to facilitate carrier injection into organic semiconductors [15e17].…”

Section: Introductionmentioning

confidence: 99%

Room-temperature and solution-processed vanadium oxide buffer layer for efficient charge injection in bottom-contact organic field-effect transistors

Jin

Jung

Song

et al. 2014

Current Applied Physics

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Section: Introductionmentioning

confidence: 99%

Room-temperature and solution-processed vanadium oxide buffer layer for efficient charge injection in bottom-contact organic field-effect transistors

Jin

Jung

Song

et al. 2014

Current Applied Physics

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“…It was also confirmed from O 1s spectra of O 2 -Au. 4 For both bare Au and O 2 -Au substrates, Au and O peak intensities exponentially decreased and C peak intensities z E-mail: jllee@postech.ac.kr increased with PEN film thickness. Negligible changes in the peak positions of Au 4f and O 1s spectra with PEN film thickness were found for both bare Au and O 2 -Au.…”

mentioning

confidence: 99%

“…3 It was reported that the contact resistance between Au and PEN could be reduced by O 2 plasma treatment on Au electrode prior to PEN deposition. 4 The surface of Au was transformed into AuO x ͑Au-O bond formation͒ when the Au surface was exposed to O 2 plasma. Enhanced crystallinity of PEN deposited on O 2 plasmatreated Au was observed.…”

mentioning

confidence: 99%

In Situ Analysis of Hole Injection Barrier of O[sub 2] Plasma-Treated Au with Pentacene Using Photoemission Spectroscopy

Kim

Lee

2007

Electrochem. Solid-State Lett.

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Pentacene was in situ deposited on both bare-Au and O 2 plasma-treated Au ͑O 2 -Au͒. The band structure at the interface of Au with pentacene was quantitatively determined using ultraviolet photoelectron spectroscopy. The work function of Au increased from 4.65 to 5.28 eV as the Au surface was treated with O 2 plasma. The corresponding interface dipoles were −0.30 eV for bare Au and −0.71 eV for O 2 -Au, respectively. Thus the hole injection barrier at the interface reduced from 0.45 to 0.15 eV by the O 2 plasma before the deposition of pentacene, leading to an increase of the linear field-effect mobility of thin-film transistors.A high work function metal is essential to obtain good ohmic contact with p-type organic semiconductor pentacene ͑PEN͒ through the small hole injection barrier at the interface of metal contact with PEN. Gold ͑Au͒ is a typical material used as a source ͑S͒ and drain ͑D͒ electrode for pentacene-based organic thin-film transistors ͑OTFTs͒ due to its chemical inertness and high work function. 1,2 However, when PEN is deposited on Au, the vacuum level shifts downward at the interface, making a barrier for holes with the barrier heights ͑⌽ BH ͒ of 0.85 eV at the Au/PEN interface. 3 It was reported that the contact resistance between Au and PEN could be reduced by O 2 plasma treatment on Au electrode prior to PEN deposition. 4 The surface of Au was transformed into AuO x ͑Au-O bond formation͒ when the Au surface was exposed to O 2 plasma. Enhanced crystallinity of PEN deposited on O 2 plasmatreated Au was observed. In addition, the oxygen chemisorption at the surface of Au increases the work function via electron transfer from gold to chemisorbed oxygen. 5 Thus it was considered that O 2 plasma treatment may reduce the ⌽ BH at the Au/PEN interface. However, the effect of O 2 plasma on the interface barrier height between Au and PEN has not been reported yet. Because the metal/ organic contact properties is a determining factor of device performances in bottom-contact ͑BC͒ OTFTs, it is important to understand the band structure between O 2 plasma-treated Au and PEN.In this paper, we report the effect of O 2 plasma treatment on hole injection barrier at the interface of PEN with Au film. The band structure at the interface was investigated using synchrotron radiation photoemission spectroscopy ͑SRPES͒ and ultraviolet photoelectron spectroscopy ͑UPS͒ with in situ deposition of PEN on both the untreated Au ͑bare Au͒ and the treated one ͑O 2 -Au͒. From these, the effect of O 2 plasma treatment on the reduction of hole injection barrier in BC OTFT is discussed.High conducting ͑ϳ5 ⍀ cm͒ n-type Si with thermally grown SiO 2 ͑300 nm thick͒ was used as the starting substrates, which functioned as the gate electrode and the gate insulator, respectively. Cr/Au ͑3/50 nm͒ films were used as S-D electrodes of OTFTs. Details of device fabrication process can be found elsewhere. 6 Electrical properties were measured using an HP-4156A semiconductor parameter analyzer in an air ambient at room temperature with r...

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“…It is thus very easy to estimate the contact resistance from the current-voltage characteristics of such a device configuration [15,544]. For instance, a TLM scheme [106,[549][550][551][552][553] was implemented using an electrode material pattern deposited on a glass substrate with a gap between adjacent electrodes from 50 to 90 μm with an increment of 5 μm [553] and depositing the OS directly on this pattern. Total contact resistance was thus determined from the measured I-V characteristics of such OFETs.…”

Section: Interface Engineering For Os Devicesmentioning

confidence: 99%

“…In order to adjust the electrical conditions at different interfaces encountered in practice, various types of SAMs were developed in the past and used in different contexts such as patterning of nanoscale devices, corrosion prevention, and controlling surface properties [518,[552][553][554][562][563][564][565][566][567][568][569][570][571][572][573][574]. SAM modification of a metal surface offers a better possibility to improve the performance of OE devices as well [518,[562][563][564][565][566][567][568][569][570][571][572][573][574].…”

Section: Interface Engineering For Os Devicesmentioning

confidence: 99%

Organic semiconductors for device applications: current trends and future prospects

Ahmad

2014

Journal of Polymer Engineering

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Abstract:With the rich experience of developing silicon devices over a period of the last six decades, it is easy to assess the suitability of a new material for device applications by examining charge carrier injection, transport, and extraction across a practically realizable architecture; surface passivation; and packaging and reliability issues besides the feasibility of preparing mechanically robust wafer/substrate of single-crystal or polycrystalline/ amorphous thin films. For material preparation, parameters such as purification of constituent materials, crystal growth, and thin-film deposition with minimum defects/ disorders are equally important. Further, it is relevant to know whether conventional semiconductor processes, already known, would be useable directly or would require completely new technologies. Having found a likely candidate after such a screening, it would be necessary to identify a specific area of application against an existing list of materials available with special reference to cost reduction considerations in large-scale production. Various families of organic semiconductors are reviewed here, especially with the objective of using them in niche areas of large-area electronic displays, flexible organic electronics, and organic photovoltaic solar cells. While doing so, it appears feasible to improve mobility and stability by adjusting π-conjugation and modifying the energy bandgap. Higher conductivity nanocomposites, formed by blending with chemically conjugated C-allotropes and metal nanoparticles, open exciting methods of designing flexible contact/interconnects for organic and flexible electronics as can be seen from the discussion included here.

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Effect of oxygen plasma treatment on reduction of contact resistivity at pentacene/Au interface

Cited by 40 publications

References 11 publications

Room-temperature and solution-processed vanadium oxide buffer layer for efficient charge injection in bottom-contact organic field-effect transistors

Room-temperature and solution-processed vanadium oxide buffer layer for efficient charge injection in bottom-contact organic field-effect transistors

In Situ Analysis of Hole Injection Barrier of O[sub 2] Plasma-Treated Au with Pentacene Using Photoemission Spectroscopy

Organic semiconductors for device applications: current trends and future prospects

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