ZnO-channel thin-film transistors: Channel mobility

Hoffman, Randy

doi:10.1063/1.1712015

Cited by 311 publications

(207 citation statements)

References 8 publications

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“…Highly conducting (doped) ZnO thin films are being used in diverse applications, such as light-emitting 1 and laser diodes, 2 architectural and automotive glazing, 3 thin-film transistors, 4,5 and high efficiency thin-film solar cells. 6 This latter makes use of ZnO as transparent conducting oxide (TCO), where a high electrical conductivity in combination with a high optical transmittance and surface texture for an enhanced optical path length 7 are required.…”

Section: Introductionmentioning

confidence: 99%

Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition

Ponomarev

Verheijen

Keuning

et al. 2012

Journal of Applied Physics

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Ponomarev, M., Verheijen, M. A., Keuning, W., Sanden, van de, M. C. M., & Creatore, M. (2012). Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition. Journal of Applied Physics, 112(4), 043708-1/7. [043708]. DOI: 10.1063/1.4747942 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Aluminum-doped ZnO (ZnO:Al) grown by chemical vapor deposition (CVD) generally exhibit a major drawback, i.e., a gradient in resistivity extending over a large range of film thickness. The present contribution addresses the plasma-enhanced CVD deposition of ZnO:Al layers by focusing on the control of the resistivity gradient and providing the solution towards thin ( 300 nm) ZnO:Al layers, exhibiting a resistivity value as low as 4 Â 10 À4 X cm. The approach chosen in this work is to enable the development of several ZnO:Al crystal orientations at the initial stages of the CVD-growth, which allow the formation of a densely packed structure exhibiting a grain size of 60-80 nm for a film thickness of 95 nm. By providing an insight into the growth of ZnO:Al layers, the present study allows exploring their application into several solar cell technologies. Highly conducting (doped) ZnO thin films are being used in diverse applications, such as light-emitting 1 and laser diodes, 2 architectural and automotive glazing, 3 thin-film transistors, 4,5 and high efficiency thin-film solar cells. 6 This latter makes use of ZnO as transparent conducting oxide (TCO), whe...

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Section: Introductionmentioning

confidence: 99%

Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition

Ponomarev

Verheijen

Keuning

et al. 2012

Journal of Applied Physics

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“…[ 3 ] The incremental mobility probing the mobility of the charge carriers induced by the gate voltage, as introduced by Hoffman, [ 40 ] is calculated in the linear operation regime (here V D = 1 V) using [ 39 ] Notably, in this approximation, the incremental mobility equals the conventional fi eld-effect mobility µ FE . The sub-threshold slope was calculated as…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, based on the peaking incremental mobility shown in Figure 3 d, the device operation is now limited by the interface scattering instead of trap limited operation which also suggests less traps present in the fi lm when compared to devices with Al-gates. [ 3,39,40 ] In a positive bias-stress (PBS) measurement for device operation stability performed at +1 MV cm −1 gate fi eld, reversible positive turn-on voltage shifts of ≈8.6 and ≈6.3 V are observed in 4000 s for devices with two InO-ink layers on Al-and Augates, respectively, which indicate charge trapping in the semiconductor fi lm or in the semiconductor-dielectric interface ( Figure S7c, Supporting Information). [ 3,39 ] The reduced V on -shift observed for the device with Au-gate supports the reduced amount of traps for the optimized Au-gated devices.…”

Section: Doi: 101002/adma201502569mentioning

confidence: 99%

“…The incremental mobility for two and three layer devices measured at the linear regime at drain voltage V D = 1 V (see Figure S7a,b, Supporting Information) is monotonously increasing with gate voltage V G from V on up to 20 V, which indicates that the devices operate at the trap-fi lling-limited mobility regime rather than in the regime where mobility is limited by semiconductor-dielectric interface scattering. [ 3,39,40 ] Since the In 2 O 3 fi lms contain nanocrystalline inclusions, the operation characteristics of the devices can be qualitatively understood based on the polycrystalline TFT model by Levinson et al [ 41 ] The grain boundaries at the edges of the crystallites have overlapping depletion regions which act as initially neutral charge traps and can compensate for possible large bulk charge carrier concentration of In 2 O 3 .…”

Section: Doi: 101002/adma201502569mentioning

confidence: 99%

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Flexography‐Printed In₂O₃ Semiconductor Layers for High‐Mobility Thin‐Film Transistors on Flexible Plastic Substrate

et al. 2015

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uniform, continuous and dense layers and is thus more suitable for printed TFTs with larger channel dimensions. Several precursor routes for solution-processed metal-oxide semiconductor layers based on metal alkoxides, [ 14,15 ] and on metal salts such as acetates, nitrates, and chlorides have been reported. [ 16,17 ] Precursors based on metal nitrates have been shown to convert into metal oxides generally at lower temperatures than acetateor chloride-based precursors. [ 17,18 ] In contrast to metal alkoxides, metal nitrates are less sensitive to air humidity and can be processed via an aqueous precursor route. [ 7 ] Based on these advantages, metal nitrates show promise as potential precursor materials for printed low-temperature-processed metal-oxide semiconductors. A large amount of work has concentrated on lowering the conversion temperature of the precursor solutions to semiconducting metal-oxide layers. Functional TFTs have been obtained at ≈200 °C or below (1) via the careful design of precursor chemistry utilizing metal alkoxides with controlled hydrolysis, [ 14,15 ] combustion process, [ 11,19 ] or the addition of oxidizing agents, [ 20 ] (2) via the use of additional energy in conversion such as various wavelengths of UV light, [ 8,15,21 ] or microwaves, [ 22 ] or (3) by employing conditions during annealing that promote effi cient precursor conversion such as ozone or vacuum. [ 6,7,20 ] After the fi rst report on inkjet-printed metal oxide layers from metal chloride precursors by Lee et al. in 2007, [ 16 ] the deposition of metal-oxide semiconductor layers for TFTs has been successfully performed via several printing techniques. [ 4 ] In addition to inkjet-printing, [ 12,16,17,19,23 ] metaloxide TFTs have been fabricated with electrodynamic-jet, [ 24 ] spray pyrolysis, [ 9 ] gravure (glass substrate, 550 °C annealing), [ 25 ] and fl exographic printing (Si wafer, 450 °C annealing). [ 26 ] The inkjet, electrodynamic jet, and spray pyrolysis techniques are typically utilized in noncontact sheet-to-sheet batch processes while the contact gravure and fl exographic printing are readily available also as continuous high-throughput roll-to-roll processes. Also novel combinations of conventional vacuum processes and techniques well known from the fi eld of printing have been proposed to prepare metal-oxide TFTs on fl exible substrates such as inkjet-printed growth inhibitors for the patterning of atomic-layer-deposited (ALD) metal-oxide layers, [ 27 ] and transferring of vacuum-processed functional TFTs from rigid to fl exible substrates by a roll-transfer method. [ 28 ] The previous results clearly indicate the challenges in the processability of materials that need to be overcome to enable large-area electronics fabrication using the industrial high-throughput additive printing processes on fl exible low-cost substrates.In this work, for the fi rst time, the metal-oxide TFT fabrication process was performed on fl exible substrate using process technologies that are roll-to-roll-compatible and industrially...

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“…Fully transparent thin film transistor (TFT) devices [3][4][5][6][7] are particularly attractive because it is expected that their characteristics will not degrade under sunlight exposure due to the wide band gap. Besides, ZnO thin films can be grown in many different polycrystalline or nanoscale forms at relatively low deposition temperatures on diverse substrates.…”

Section: Introductionmentioning

confidence: 99%

Study of trap states in zinc oxide (ZnO) thin films for electronic applications

Casteleiro¹,

Gomes²,

Stallinga³

et al. 2008

Journal of Non-Crystalline Solids

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The electrical properties of ZnO thin films grown by pulsed laser deposition were studied. Field-effect devices with a mobility reaching 1 cm 2 /V s show non-linearities both in the current-voltage and in the transfer characteristics which are explained as due to the presence of trap states. These traps cause a reversible threshold voltage shift as revealed by low-frequency capacitance-voltage measurements in metal insulator semiconductor (MIS) capacitors. Thermal detrapping experiments in heterojunctions confirm the presence of a trap state located at 0.32 eV.

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ZnO-channel thin-film transistors: Channel mobility

Cited by 311 publications

References 8 publications

Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition

Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition

Flexography‐Printed In₂O₃ Semiconductor Layers for High‐Mobility Thin‐Film Transistors on Flexible Plastic Substrate

Study of trap states in zinc oxide (ZnO) thin films for electronic applications

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ZnO-channel thin-film transistors: Channel mobility

Cited by 311 publications

References 8 publications

Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition

Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition

Flexography‐Printed In2O3 Semiconductor Layers for High‐Mobility Thin‐Film Transistors on Flexible Plastic Substrate

Study of trap states in zinc oxide (ZnO) thin films for electronic applications

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Flexography‐Printed In₂O₃ Semiconductor Layers for High‐Mobility Thin‐Film Transistors on Flexible Plastic Substrate