Effect of thickness of ZnO active layer on ZnO-TFT's characteristics

Chung, Jihoon; Lee, J.Y.; Kim, H.S.; Jang, Nakwon; Kim, J.H.

doi:10.1016/j.tsf.2007.07.107

Cited by 76 publications

(37 citation statements)

References 8 publications

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“…Transparent thin-film transistors (TTFTs) [1][2][3][4][5] using amorphous films as an active channel have attracted considerable attention with the hope of developing entirely transparent active matrix displays. Although amorphous films have smooth surfaces and can enable better interfacing between the gate dielectric and active channel, they have limitations as a channel material because their mobility is lower than that of polycrystalline films.…”

Section: Introductionmentioning

confidence: 99%

Highly transparent and resistive nanocrystalline ZnO-SnO₂films prepared by rf magnetron sputtering

Cha¹,

Choi²,

Ma³

2012

Journal of Electrical Engineering and Technology

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-ZnO-SnO 2 films were deposited by rf magnetron sputtering using a ZnO-SnO 2 (2:1 molar ratio) target. The target was made from a mixture of ZnO and SnO 2 powders calcined at 800°C. The working pressure was 1 mTorr, and the rf power was 120 W. The ratio of oxygen to argon (O 2 :Ar) was varied from 0% to 10%, and the substrate temperature was varied from 27°C to 300°C. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force spectroscopy (AFM). The ZnO-SnO 2 films deposited in O 2 :Ar = 10% exhibited resistivity higher than 10 6 Ωcm and transmittance of more than 80% in the visible range.

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Section: Introductionmentioning

confidence: 99%

Highly transparent and resistive nanocrystalline ZnO-SnO₂films prepared by rf magnetron sputtering

Cha¹,

Choi²,

Ma³

2012

Journal of Electrical Engineering and Technology

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“…Some studies have reported a considerable impact of semiconductor thickness on the electrical properties of TFTs. 31,37,41,42 These reports show that channel mobility and I off increase and the threshold voltage decreases with increasing semiconductor layer thickness. Thus, an alternative approach to improve the I on /I off parameter of the devices with ZnO films deposited at 3 mTorr and 5 mTorr would be reduction of the channel thickness.…”

Section: Resultsmentioning

confidence: 95%

“…Such an effect has already been observed in previous reports. 31,37 To determine the electrical resistivity of the ZnO layers in all the devices, we employed the I DS -V DS data of the TFTs measured at V GS = 0 V. Figure 9 shows the electrical resistivity (q) versus the deposition pressure of the ZnO layers for L = 20 lm, 40 lm, and 80 lm channel lengths. The observed increasing resistivity with increasing channel length can be attributed to series resistance effects, 38 which is more evident in higherresistive ZnO films (8 mTorr and 10 mTorr).…”

Section: Resultsmentioning

confidence: 99%

Effect of Sputtered ZnO Layers on Behavior of Thin-Film Transistors Deposited at Room Temperature in a Nonreactive Atmosphere

Medina-Montes

Lee

Perez

et al. 2011

Journal of Elec Materi

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In this work we present the electrical characterization of ZnO-based thin-film transistors fabricated at room temperature. The ZnO films were deposited by radiofrequency magnetron sputtering at variable argon pressure (3 mTorr to 10 mTorr) at room temperature. The sputtered ZnO films were polycrystalline with hexagonal structure and electrical resistivity ranging from 10 1 X cm to 10 8 X cm for films deposited from 3 mTorr to 10 mTorr. The trend in the electrical behavior of the devices was found to be due to the variation of the electron concentration of the ZnO films. The devices with better performance showed a field-effect mobility of 2.9 cm 2 /Vs, threshold voltage of 20 V, I on / I off % 10 6 , and electrical resistivity of $10 8 X cm. In addition, linear behavior of I on /I off with deposition pressure was observed. The lowest I on /I off ratio ($2) was calculated for devices with ZnO layers deposited at 3 mTorr, and the highest ratio ($10 6 ) for devices processed at 10 mTorr. Hall-effect measurements were performed on ZnO films showing the lowest resistivity. The layer grown at 3 mTorr showed a Hall mobility of l H = 8.9 cm 2 /Vs and carrier concentration of n = 4.2 9 10 16 cm À3 with resistivity of q = 31.8 X cm. For films deposited at 5 mTorr, the Hall mobility, carrier concentration, and resistivity were l H = 7.9 cm 2 /Vs, n = 3.4 9 10 16 cm À3 , and q = 38.4 X cm, respectively. Films deposited at 8 mTorr and 10 mTorr could not be measured due to their high resistance.

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“…The electrical properties of the ZnO thin films strongly depend on their grain size and crystallinity. [14,15] Our ALD process includes a high density of hydroxyl groups due to water vapor source, and it provides oxygen-rich atmosphere in the initial growth stage, which leads to the formation of the more insulating films with reduced carrier density. Figure 3 shows the output curves for the TFTs with different channel thickness and the effect of thermal treatment.…”

Section: Resultsmentioning

confidence: 99%

Influence of active layer thickness and annealing in zinc oxide TFT grown by atomic layer deposition

Ahn

Woo

Hwang

et al. 2010

Surface & Interface Analysis

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aWe utilized atomic layer deposition (ALD) for the growth of the ZnO channel layers in the oxide thin-film-transistors (TFTs) with a bottom-gate structure using a SiO 2 /p-Si substrate. For fundamental study, the effect of the channel thickness and thermal treatment on the TFT performance was investigated. The growth modes for the ALD-grown ZnO layer changed from island growth to layer-by-layer growth at thicknesses of >7.5 nm with highly resistive properties. A channel thickness of 17 nm resulted in good TFT behavior with an on/off current ratio of >10 6 and a field effect mobility of 2.9 without the need for thermal annealing. However, further increases in the channel thickness resulted in a deterioration of the TFT performance, or no saturation. The ALD-grown ZnO layers showed reduced electrical resistivity and carrier density after thermal treatment in oxygen.

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Effect of thickness of ZnO active layer on ZnO-TFT's characteristics

Cited by 76 publications

References 8 publications

Highly transparent and resistive nanocrystalline ZnO-SnO₂films prepared by rf magnetron sputtering

Highly transparent and resistive nanocrystalline ZnO-SnO₂films prepared by rf magnetron sputtering

Effect of Sputtered ZnO Layers on Behavior of Thin-Film Transistors Deposited at Room Temperature in a Nonreactive Atmosphere

Influence of active layer thickness and annealing in zinc oxide TFT grown by atomic layer deposition

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Effect of thickness of ZnO active layer on ZnO-TFT's characteristics

Cited by 76 publications

References 8 publications

Highly transparent and resistive nanocrystalline ZnO-SnO2films prepared by rf magnetron sputtering

Highly transparent and resistive nanocrystalline ZnO-SnO2films prepared by rf magnetron sputtering

Effect of Sputtered ZnO Layers on Behavior of Thin-Film Transistors Deposited at Room Temperature in a Nonreactive Atmosphere

Influence of active layer thickness and annealing in zinc oxide TFT grown by atomic layer deposition

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Highly transparent and resistive nanocrystalline ZnO-SnO₂films prepared by rf magnetron sputtering

Highly transparent and resistive nanocrystalline ZnO-SnO₂films prepared by rf magnetron sputtering