• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.10-10
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• 2009

We have fabricated transparent and flexible thin film transistor(TFT) on polyethylene terephthalate(PET) substrate using Zinc Oxide (ZnO) and Indium Tin Oxide (ITO) film as active layer and electrode. The transfer printing method was used for printing the device layer on target plastic substrate at room temperature. This approach have an advantage to separate the high temperature annealing process to improve the electrical properties of ZnO TFT from the device process on plastic substrate. The resulting devices on plastic substrate presented mechanical and electrical properties similar with those on rigid substrate.

• 한국세라믹학회지
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• 제31권11호
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• pp.1396-1400
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• 1994

Electrical properties in the ZnO-Bi2O3-CoO-Zn7Sb2O12 system were investigated with Zn7Sb2O12 content (0.1~2 mol%). The increase of the Zn7Sb2O12 content inhibited the grain growth of ZnO, which showed a narrow grain size distribution of ZnO. The breakdown voltage (Vb) increased markedly with 1 mol% Zn7Sb2O12 addition due to the grain growth control behaviour of the Zn7Sb2O12 . The nonlinear I-V characteristic was significantly influenced by the Zn7Sb2O12 content (or Bi2O3/Zn7Sb2O12 ratio). Addition of 0.5 mol% Zn7Sb2O12 showed the highest nonlinear coefficient ($\alpha$) of 43. The leakage current in prebreakdown region was decreased with increasing Zn7Sb2O12 content.

• 한국재료학회지
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• 제26권2호
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• pp.84-89
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• 2016

We present the rectifying and nitrogen monoxide (NO) gas sensing properties of an oxide semiconductor heterostructure composed of n-type zinc oxide (ZnO) and p-type copper oxide thin layers. A CuO thin layer was first formed on an indium-tin-oxide-coated glass substrate by sol-gel spin coating method using copper acetate monohydrate and diethanolamine as precursors; then, to form a p-n oxide heterostructure, a ZnO thin layer was spin-coated on the CuO layer using copper zinc dihydrate and diethanolamine. The crystalline structures and microstructures of the heterojunction materials were examined using X-ray diffraction and scanning electron microscopy. The observed current-voltage characteristics of the p-n oxide heterostructure showed a non-linear diode-like rectifying behavior at various temperatures ranging from room temperature to $200^{\circ}C$. When the spin-coated ZnO/CuO heterojunction was exposed to the acceptor gas NO in dry air, a significant increase in the forward diode current of the p-n junction was observed. It was found that the NO gas response of the ZnO/CuO heterostructure exhibited a maximum value at an operating temperature as low as $100^{\circ}C$ and increased gradually with increasing of the NO gas concentration up to 30 ppm. The experimental results indicate that the spin-coated ZnO/CuO heterojunction structure has significant potential applications for gas sensors and other oxide electronics.

• 한국전기전자재료학회논문지
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• 제20권8호
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• pp.711-715
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• 2007

Properties of organic light-emitting diodes (OLEDs) with aluminum-doped zinc oxide (ZnO:Al) anodes showed different behaviors from OLEDs with indium tin oxide (ITO) anodes according to driving conditions. OLEDs with ITO anodes gave higher current density and luminance in lower voltage region and better EL and power efficiency under lower current density conditions, However, OLEDs with ZnO:Al anodes gave higher current density and luminance in higher voltage region over about 8V and better EL and power efficiency under higher current density over $200mA/cm^2$. These seemed to be due to the differences in conduction properties of semiconducting ZnO:Al and metallic ITO. OLEDs with ZnO:Al anodes showed nearly saturated efficiency under high current driving conditions compared with those of OLEDs with ITO anodes. This meant better charge balance in OLEDs with ZnO:Al anodes. These properties of OLEDs with ZnO:Al anodes are useful in making bright display devices with efficiency.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.252-253
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• 2011

ZnO-based thin film transistors (TFTs) are of great interest for application in next generation flat panel displays. Most research has been based on amorphous indium-gallium-zinc-oxide (IGZO) TFTs, rather than single binary oxides, such as ZnO, due to the reproducibility, uniformity, and surface smoothness of the IGZO active channel layer. However, recently, intrinsic ZnO-TFTs have been investigated, and TFT- arrayss have been demonstrated as prototypes of flat-panel displays and electronic circuits. However, ZnO thin films have some significant problems for application as an active channel layer of TFTs; it was easy to change the electrical properties of the i-ZnO thin films under external conditions. The variable electrical properties lead to unstable TFTs device characteristics under bias stress and/or temperature. In order to obtain higher performance and more stable ZnO-based TFTs, HZO thin film was used as an active channel layer. It was expected that HZO-TFTs would have more stable electrical characteristics under gate bias stress conditions because the binding energy of Hf-O is greater than that of Zn-O. For deposition of HZO thin films, Hf would be substituted with Zn, and then Hf could be suppressed to generate oxygen vacancies. In this study, the fabrication of the oxide-based TFTs with HZO active channel layer was reported with excellent stability. Application of HZO thin films as an active channel layer improved the TFT device performance and bias stability, as compared to i-ZnO TFTs. The excellent negative bias temperature stress (NBTS) stability of the device was analyzed using the HZO and i-ZnO TFTs transfer curves acquired at a high temperature (473 K).

• 한국표면공학회지
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• 제54권5호
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• pp.260-266
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• 2021

Synthesizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate highly efficient gas sensors by means of possible enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned zinc oxide (ZnO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Zn metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the ZnO nanorods array of the single hexagonal wurtzite crystalline phase. From gas sensing measurements for the nitrogen dioxide (NO₂) gas, the vertically aligned ZnO nanorod array is observed to have a highly responsive sensitivity to NO₂ gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO₂ at 250 ℃ and a low NO₂ detection limit of 5 ppm in dry air. These results along with a facile fabrication process demonstrate that the ZnO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO₂ gas sensors.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1351-1355
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• 2018

The photocurrent characteristics of zinc-oxide (ZnO) thin-film transistors (TFTs) prepared using radio-frequency sputtering and spin-coating methods were investigated. Various characterization methods were used to compare the physical and the chemical properties of the sputtered and the spin-coated ZnO films. X-ray photoelectron spectroscopy was used to investigate the chemical composition and state of the ZnO films. The transmittance and the optical band gap were measured by using UV-vis spectrometry. The crystal structures of the prepared ZnO films were examined by using an X-ray diffractometer, and the surfaces of the films were investigated by using scanning electron microscopy. ZnO TFTs were prepared using both sputter and solution processes, both of which showed photocurrent characteristics when illuminated by light. The sputtered ZnO TFTs had a photoresponsivity of 3.08 mA/W under illumination with 405-nm light while the solution-processed ZnO TFTs had a photoresponsivity of 5.56 mA/W. This study provides useful information for the development of optoelectronics based on ZnO.

• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.789-794
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• 2008

Zinc oxide (ZnO) has been widely studied for its practical applications such as transparent conduction electrodes for flat panel displays and solar cells. Especially, ZnO films show good chemical stability against hydrogen plasma, absence of toxicity, abundance in nature, and then suitable for photovoltaic applications. However, the fabrication process of thin film solar cells require a high substrate temperature and/or post heat treatment. Therefore, the layers have to withstand high temperatures, requiring an excellent stability without degrading their electronic and optical properties. In this paper, we investigated the stability of zinc oxide (ZnO) films doped with aluminum and hydrogen. Doped ZnO films were prepared by r.f. magnetron sputter and followed by heat treatment at different temperatures and for various times.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권3호
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• pp.111-114
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• 2002

Using the plasma that we developed to generate a low-temperature plasma at atmospheric pressure, we have investigated the etching possibility of an air-exposed zinc oxide(ZnO) thin films. Hydrogen and methane radicals generated from the plasma were observed and their intensity was found to be dependent on the isomer of butyl acetate by an analysis with optical emission spectrosxopy. The etching ability of this plasma was evaluated by an emission intensity, etching time, rf power.

• 한국표면공학회지
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• 제33권4호
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• pp.229-232
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• 2000

C-axis oriented zinc oxide thin films were deposited on glass substrate by reactive Facing Targets Sputtering (FTS) system. The characteristics of zinc oxide thin films on power, inter targets distance, and substrate temperature were investigated by XRD(x-ray diffractometer), alphastep (Tencor) analyses. The Facing Targets Sputtering system can deposit thin film in plasma-free situation and change the deposition condition in wide range. The excellently c-axis oriented zinc oxide thin films were obtained at sputter pressure 1mTorr, sputtering current 0.4A, substrate temperature $300^{\circ}C$, inter targets distance 100mm. In the conditions, the rocking curve of zinc oxide thin films deposited on ZnO/Glass was $3.9^{\circ}$.