• Transactions on Electrical and Electronic Materials
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• v.11 no.6
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• pp.253-256
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• 2010

Different active layer thicknesses for zinc oxide (ZnO) bottom-contact thin-film transistors (TFTs) were fabricated with a poly-4-vinyphenol polymeric dielectric using injector type atomic layer deposition. The properties of the ZnO TFTs were influenced by the active thickness and width-to-length (W/L) ratio of the device. The threshold voltage of ZnO TFTs shifted positively as the active layer thickness decreased, while the subthreshold slope decreased. The W/L ratio of ZnO TFTs also affected the mobility and subthreshold slope. An optimized TFT structure exhibited an on-tooff current ratio of above 106 with solid saturation.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.582-582
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• 2013

Oxide TFT (thin film transistor) active channel layer에 대한 저온 열처리 공정은 투명하고 flexibility을 기반으로하는 display 산업과 AMOLED (active matrix organic light emitting diode) 분야 등 다양한 분야에서 필요로 하는 기술로서 많은 연구가 이루어지고 있다. 과거 active layer는 ALD (atomic layer deposition), CVD (chemical vapor deposition), pulse laser deposition, radio frequency-dc (RF-dc) magnetron sputtering 등과 같은 고가의 진공 장비를 이용하여 증착 되어져 왔으나 현재에는 진공 장비 없이 spin-coating 후 열처리 하는 저가의 공정이 주로 연구되어 지고 있다. Flexible 기판들은 일반적인 OTFT (oxide thin films Transistor)에 적용되는 열처리 온도로 공정 진행시 열에 의한 기판의 손상이 발생한다. Flexible substrate의 열에 의한 기판 손상을 막기 위해 저온 열처리 공정이 연구되고 있지만 기존 열처리와 비교하여 소자의 특성 저하가 동반 되었다. 본 연구에서는 Si 기판위에 SiO2 (100)를 절연층으로 증착하고 그 위에 IZO (indium zinc oxide) solution을 spin-coating 한뒤 $250^{\circ}C$ 이하의 온도에서 열처리하였다. 저온 공정으로 인하여 소자의 특성 저하가 동반 되었으므로 소자의 저하된 특성 복원하고자 post-treatment로 고가의 진공장비가 필요 없고 roll-to roll system 적용이 수월한 remote-type의 APP (atmospheric pressure plasma) 처리를 하였다. Post-treatment로 APP를 이용하여 $250^{\circ}C$ 이하에서 소자에 적용 가능한 on/off ratio를 얻을 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.84.2-84.2
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• 2011

In this research, two thin film deposition techniques, Atomic Layer Deposition and Sputtering are carried out for the fabrication of Yittria Stabilized Zirconia electrolyte for thin film Solid Oxide Fuel Cell. Zirconium to Yittrium ratio for both cases is about 1/8. Scanning Electron Microscope(SEM) image shows that the growth rate per hour for Atomic Layer Deposition is faster than for sputtering. X-ray Photo-electron Spectroscopy(XPS) shows that the peaks of both Zirconia and Yittria shift towards higher bending energy for the case of Atomic Layer deposition and thus are more strongly attached to the substrate. Later, Nyquist plot was used to compare the conductivity of Yittria Stabilized Electrolyte for both cases. The conductivity at $300^{\circ}C$ for Atomic Layer Deposited Yittria Stabilized Zirconia is found to be $5{\times}10^{-4}S/cm$ while that for sputtered Yittria Stabilized Zirconia is $2{\times}10^{-5}S/cm$ at the same temperature. The reason for better performance for Atomic Layered YSZ is believed to be the Nano-structured layer fabrication that aids in along the plane conduction as compared to the columnarly structured Sputtered YSZ.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.153-160
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• 2011

The AISI 216L stainless steel with a composition of Fe-16Cr-6Ni-6Mn-1.7Mo (wt.%) was oxidized at $700{\sim}900^{\circ}C$ in air for 100 h. At $700^{\circ}C$, a thin $Mn_{1.5}Cr_{1.5}O_4$ oxide layer with a thickness of $0.4{\mu}m$ formed. At $800^{\circ}C$, an outer thin $Fe_2O_3$ oxide layer and a thick inner $FeCr_2O_4$ oxide layer with a total thickness of $30{\mu}m$ formed. The non-adherent scale formed at $800^{\circ}C$ was susceptible to cracking. At $900^{\circ}C$, an outer thin $Fe_2O_3$ oxide layer and a thick inner $Mn_{1.5}Cr_{1.5}O_4$ oxide layer formed, whose total thickness was $10{\sim}15{\mu}m$. The scales formed at $900^{\circ}C$ were non-adherent and susceptible to cracking. 216 L stainless steel oxidized faster than 316 L stainless steel, owing to the increment of the Mn content and the decrement of Ni content.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1003-1004
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• 2011

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.296-298
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• 1997

The performance of thin film pressure sensors with polyimide and silicon oxide as a insulating layer between the stainless steel diaphragm and the Cu-Ni strain gauges is presented. The polyimide was spun on the stainless steel diaphragm and cured in an oven. The silicon oxide was deposited by rf sputtering. The thin film pressure sensor with silicon oxide as a insulating layer showed a better nonlinearity and a lower hysteresis.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.421.1-421.1
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• 2016

We studied indium-doped zinc oxide (IZO) film grown by atomic layer deposition (ALD) as transparent conductive oxide (TCO). A variety of TCO layer, such as ZnO:Al (AZO), InSnO2(ITO), Zn (O,S) etc, has been grown by various method, such as ALD, chemical vapor deposition (CVD), sputtering, laser ablation, sol-gel technique, etc. Among many deposition methods, ALD has various advantages such as uniformity of film thickness, film composition, conformality, and low temperature deposition, as compared with other techniques. In this study, we deposited indium-doped zinc oxide thin films using diethyl[bis(trimethylsilyl)amido]indium [Et2InN(TMS)2] as indium precursor, DEZn as zinc precursor and H2O as oxidant for ALD and investigated the optical and electrical properties of IZO films. As an alternative, this liquid In precursor would has several advantages in indium oxide thin-film processes by ALD, especially for low resistance indium oxide thin film and high deposition rate as compared to InCp, InCl3, TMIn precursors etc. We found out that Indium oxide films grown by Et2InN(TMS)2 and H2O precursor show ALD growth mode and ALD growth window. We also found out the different growth rate of Indium oxide as the substrate and investigated the effect of the substrate on Indium oxide growth.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.273-277
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• 2018

This research introduces the sputtered IZO thin film transistor (TFT) with solution-processed $Al_2O_3$ diffusion layer. IZO is one of the most commonly used amorphous oxide semiconductor (AOS) TFT. However, most AOS TFTs have many defects that degrade performance. Especially oxygen vacancy in the active layer. In previous research, aluminum was used as a carrier suppressor by binding the oxygen vacancy and making a strong bond with oxygen atoms. In this paper, we use a solution-processed $Al_2O_3$ diffusion layer to fabricate stable IZO TFTs. A double-layer solution-processed $Al_2O_3$-sputtered IZO TFT showed better performance and stability, compared to normal sputtered IZO TFT.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.263-270
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• 2000

The Pt/copper oxide/n-Si electrodes were fabricated by depositing copper oxide thin film of 500${\AA}$ and very thin Pt layer on the n-type (100) Si substrate. hotoelectrochemical properties and stability profiles of the electrodes were investigated as a function of deposition time of Pt layer. As the deposition time of Pt layer increased up to 10 seconds, the photocurrent and quantum efficiency were increased and then decreased with further depositing time. The better cell stability was observed for the electrode with longer deposition time. The improvements in above photoelectrochemical properties indicate that Pt layer acts as a catalyst layer at electrode/electrolyte interface as well as a protective layer. The decreasing tendency of the photocurrent and efficiency for the electrode with Pt layer deposited above 20 seconds was explained as an increases in probbility of electron-hole pair recombination and also the absorbing photon loss at electrode surface due to the excessive thickness of Pt layer. The results were confirmed by impedance spectroscopy, mutiple cycle voltammograms and microstructural analyses.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.211.1-211.1
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• 2013

We fabricate the conductive zinc oxide(ZnO) thin film using UV-enhanced atomic layer deposition. ZnO is semiconductor with a wide band gap(3.37eV) and transparent in the visible region. ZnO can be deposited with various method, such as metal organic chemical vapour deposition, magnetron sputtering and pulsed laser ablation deposition. In this experiment, ZnO thin films was deposited by atomic layer deposition using diethylzinc (DEZ) and D.I water as precursors with UV irradiation during water dosing. As a function of UV exposure time, the resistivity of ZnO thin films decreased dramatically. We were able to confirm that UV irradiation is one of the effective way to improve conductivity of ZnO thin film. The resistivity was investigated by 4 point probe. Additionally, we confirm the thin film composition is ZnO by X-ray photoelectron spectroscopy. We anticipate that this UV-enhanced ZnO thin film can be applied to electronics or photonic devices as transparent electrode.