Low-voltage ZnO thin-film transistors based on Y2O3 and Al2O3 high-k dielectrics deposited by spray pyrolysis in air

Adamopoulos, George; Thomas, Stuart; Bradley, Donal D. C.; McLachlan, Martyn A.; Anthopoulos, Thomas D.

doi:10.1063/1.3568893

Cited by 130 publications

(96 citation statements)

References 27 publications

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“…Multiple metal oxides have been proposed as alternatives to SiO 2 including aluminium oxide (AlO x ), 5,6 hafnium oxide (HfO x ), 7,8 and zirconium oxide (ZrO x ), 9,10 all of which have higher dielectric constants. These alternative metal oxide dielectrics can also be produced from solutions by employing analogous routes to those used by solution-processed metal oxide semiconductors.…”

confidence: 99%

Electron mobility enhancement in solution-processed low-voltage In2O3 transistors via channel interface planarization

et al. 2018

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The quality of the gate dielectric/semiconductor interface in thin-film transistors (TFTs) is known to determine the optimum operating characteristics attainable. As a result in recent years the development of methodologies that aim to improve the channel interface quality has become a priority. Herein, we study the impact of the surface morphology of three solution-processed high-k metal oxide dielectrics, namely AlOx, HfOx, and ZrOx, on the operating characteristics of In2O3 TFTs. Six different dielectric configurations were produced via single or double-step spin-casting of the various precursor formulations. All layers exhibited high areal capacitance in the range of 200 to 575 nF/cm2, hence proving suitable, for application in low-voltage n-channel In2O3 TFTs. Study of the surface topography of the various layers indicates that double spin-cast dielectrics exhibit consistently smoother layer surfaces and yield TFTs with improved operating characteristics manifested, primarily, as an increase in the electron mobility (µ). To this end, µ is found to increase from 1 to 2 cm2/Vs for AlOx, 1.8 to 6.4 cm2/Vs for HfOx, and 2.8 to 18.7 cm2/Vs for ZrOx-based In2O3 TFTs utilizing single and double-layer dielectric, respectively. The proposed method is simple and potentially applicable to other metal oxide dielectrics and semiconductors.

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confidence: 99%

Electron mobility enhancement in solution-processed low-voltage In2O3 transistors via channel interface planarization

et al. 2018

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“…This has been boosted mainly by the extraordinary combination of ZnO's assets, such as its chemical stability (enthalpy of formation D f H o ¼ À348 kJ/mol), abundance of constituent elements, a direct optical band gap (E g ¼ 3.34 eV), comparable to that of GaN, 4 its inherent n-type character, 5 and the ability to fabricate it using a variety of methods such as magnetron sputtering, 6 molecular beam epitaxy, 7 metalorganic chemical vapor deposition, 8 and spray pyrolysis. 9 A major asset of ZnO is that its Photoluminescence (PL) spectra consist of two emission components: a narrow UltraViolet (UV) peak at around 380 nm, which is correlated with the near band-edge (NBE) exciton emission, 10 and a broad visible (VIS) peak spanning from 450 to 750 nm, which is associated with deep level emission (DLE) from intrinsic and extrinsic defects. [11][12][13][14] The fabrication of high-quality ZnO films with strong UV or VIS emission is a challenging task; a high-temperature deposition or/and a post-deposition annealing scheme is usually required 15,16 with thermal annealing 17 and rapid thermal annealing, 18 which however are not compatible with temperature sensitive underlayers, such as thin metal layers.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence enhancement of ZnO via coupling with surface plasmons on Al thin films

Dellis

Kalfagiannis

Kassavetis

et al. 2017

Journal of Applied Physics

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We present that the ultra-violet emission of ZnO can be enhanced, as much as six-times its integral intensity, using an Al thin interlayer film between the Si substrate and ZnO thin film and a postfabrication laser annealing process. The laser annealing is a cold process that preserves the chemical state and integrity of the underlying aluminum layer, while it is essential for the improvement of the ZnO performance as a light emitter and leads to enhanced emission in the visible and in the ultraviolet spectral ranges. In all cases, the metal interlayer enhances the intensity of the emitted light, either through coupling of the surface plasmon that is excited at the Al/ZnO interface, in the case of light-emitting ZnO in the ultraviolet region, or by the increased back reflection from the Al layer, in the case of the visible emission. In order to evaluate the process and develop a solid understanding of the relevant physical phenomena, we investigated the effects of various metals as interlayers (Al, Ag, and Au), the metal interlayer thickness, and the incorporation of a dielectric spacer layer between Al and ZnO. Based on these experiments, Al emerged as the undisputable best choice of metal interlayers because of its compatibility with the laser annealing process, as well as due to its high optical reflectivity at 380 and 248 nm, which leads to the effective coupling with surface plasmons at the Al/ZnO interfaces at 380 nm and the secondary annealing of ZnO by the backreflected 248 nm laser beam. Published by AIP Publishing. [http://dx

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“…6 Therefore, the rapid formation and the extremely strong electrostatic coupling effect of an EDL with a large capacitance at the conjugated polymer/electrolyte interface results in a fast and robust field effect transistors, which are capable of operating at low voltages. 7,8 In our previous work, low voltage (<1.5 V) oxide-based EDL TFTs, which is gated by microporous SiO 2 solid electrolyte films after being soaked in phosphoric acid, have been demonstrated. 9 However, Indium Zinc Oxide (IZO) EDL TFTs need to be exposed to the environment for proper operations.…”

Section: Introductionmentioning

confidence: 99%

Effects of humidity on performance of electric-double-layer oxide-based thin-film transistors gated by nanogranular SiO2 solid electrolyte

Yang

Zhu

et al. 2013

AIP Advances

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Electric-double-layer oxide-based thin-film transistors gated by nanogranular SiO2 solid electrolyte have been fabricated at room temperature. The effects of humidity on performances are investigated. At the relative humidity of 65 %, the measured capacitance is 10 μF/cm2, and the device shows Ion/off ratio of 8.93 × 107, field-effect mobility of 5.9 cm2/Vs. As relative humidity declines, the measured capacitance decreases, which gives rise to the degradation in performance. Especially, at the relative humidity of 0 %, the capacitance of 0.01 μF/cm2 is measured, so the device cannot be turned off. The reason may be that humidity can promote H2O molecules to permeate into solid electrolyte, which can cause charges accumulation

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Low-voltage ZnO thin-film transistors based on Y2O3 and Al2O3 high-k dielectrics deposited by spray pyrolysis in air

Cited by 130 publications

References 27 publications

Electron mobility enhancement in solution-processed low-voltage In2O3 transistors via channel interface planarization

Electron mobility enhancement in solution-processed low-voltage In2O3 transistors via channel interface planarization

Photoluminescence enhancement of ZnO via coupling with surface plasmons on Al thin films

Effects of humidity on performance of electric-double-layer oxide-based thin-film transistors gated by nanogranular SiO2 solid electrolyte

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