• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 추계학술대회 논문집
• /
• pp.233-244
• /
• 2004

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_2O_3$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193nm) excimer laser. The epilayers of ZnO were achieved on sapphire ($Al_2O_3$)substrate at a temperature of $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}10^{16}\;cm^{-3}$ and $299\;{\textrm}cm^2/V.s$ at 293K. respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;3.3973\;eV\;-\;(2.69{\times}10^{-4}\;eV/K)T^2/(T+463K)$. After the as-grown ZnO epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO atmospheres has been investigated by the photoluminescence(PL) at 10K. The native defects of $V_{zn},\;Vo,\;Zn_{int},\;and\;O_{int}$ obtained by PL measurements were classified as a donors or acceptors type. In addition, we concluded that the heat-treatment in the oxygen atmosphere converted ZnO thin films to an optical p-type. Also, we confirmed that vacuum in $ZnO/Al_2O_3$ did not form the native defects because vacuum in ZnO thin films existed in the form of stable bonds.

• 한국전기전자재료학회논문지
• /
• 제25권10호
• /
• pp.811-816
• /
• 2012

The effect of co-sputtering condition on the structural properties of $Mg_xZn_{1-x}O$ thin films grown by RF magnetron co-sputtering system was investigated for manufacturing ZnO/MgZnO structure LED. $Mg_xZn_{1-x}O$ thin films were grown with ZnO and MgO target varying RF power. Structural properties were investigated by X-ray diffraction (XRD) and Energy dispersive spectroscopy (EDS). The ZnO thin films have sufficient crystallinity on the high RF power. As RF power of ZnO target increased, the contents of MgO in the $Mg_xZn_{1-x}O$ film decreased. LED was manufactured using ZnO/MgZnO multi-layer on p-GaN/$Al_2O_3$ substrate. Threshold voltage of multi-layer LED was appeared at 8 V, and it was luminesced at wave length of 550 nm.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.166-166
• /
• 2010

Recently, TFTs based on amorphous oxide semiconductors (AOSs) such as ZnO, InZnO, ZnSnO, GaZnO, TiOx, InGaZnO(IGZO), SnGaZnO, etc. have been attracting a grate deal of attention as potential alternatives to existing TFT technology to meet emerging technological demands where Si-based or organic electronics cannot provide a solution. Since, in 2003, Masuda et al. and Nomura et al. have reported on transparent TFTs using ZnO and IGZO as active layers, respectively, much efforts have been devoted to develop oxide TFTs using aforementioned amorphous oxide semiconductors as their active layers. In this thesis, I report on the performance of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer at room temperature. $SiO_2$ was employed as the gate dielectric oxide. The amorphous indium gallium zinc oxides were deposited by RF magnetron sputtering. The carrier concentration of amorphous indium gallium zinc oxide was controlled by oxygen pressure in the sputtering ambient. Devices are realized that display a threshold voltage of 1.5V and an on/off ration of > $10^9$ operated as an n-type enhancement mode with saturation mobility with $9.06\;cm^2/V{\cdot}s$. The devices show optical transmittance above 80% in the visible range. In conclusion, the fabrication and characterization of thin-film transistors using amorphous indium gallium zinc oxides for an active channel layer were reported. The operation of the devices was an n-type enhancement mode with good saturation characteristics.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.461-463
• /
• 2009

We report on the fabrication of ZnO-based thin-film transistor (TFT) inverters with top and bottom gate structures with $Al_2O_3$ dielectrics grown by atomic layer deposition (ALD). Since the top gate ZnO-based TFT showed somewhat lower field effect mobility than that of the bottom gate device, our ZnO-based TFT inverters were designed with identical dimensions for both channels. This TFT inverter device demonstrated an high voltage gain at a low supply voltage of 5 V and clear dynamic behavior.

• Journal of Information Display
• /
• 제10권4호
• /
• pp.137-142
• /
• 2009

Transparent top-gate Al-Zn-Sn-O (AZTO) thin-film transistors (TFTs) with an $Al_2O_3$ protective layer (PL) on an active layer were studied, and a transparent 2.5-inch QCIF+AMOLED (active-matrix organic light-emitting diode) display panel was fabricated using an AZTO TFT backplane. The AZTO active layers were deposited via RF magnetron sputtering at room temperature, and the PL was deposited via two different atomic-layer deposition (ALD) processes. The mobility and subthreshold slope were superior in the TFTs annealed in vacuum and with oxygen plasma PLs compared to the TFTs annealed in $O_2$ and with water vapor PLs, but the bias stability of the TFTs annealed in $O_2$ and with water vapor PLs was excellent.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.304.2-304.2
• /
• 2016

Hafnium oxide-aluminum oxide (HfO2-Al2O3) dielectric films have been fabricated by Pulsed Laser Deposition (PLD), and their properties are studied in comparison with HfO2 films. As a gate dielectric of the TFT, in spite of its high dielectric constant, HfO2 has a small energy band gap and microcrystalline structure with rough surface characteristics. When fabricated by the device, it has the drawback of generating a high leakage current. In this study, the HfAlO films was obtained by Pulsed Laser Deposition with HfO2-Al2O3 target(chemical composition of (HfO2)86wt%(Al2O3)14wt%). The characteristics of the thin Film have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM) and spectroscopic ellipsometer (SE) analyses. The X-ray diffraction studies confirmed that the HfAlO has amorphous structure. The RMS value can be compared to the surface roughness via AFM analysis, it showed HfAlO thin Film has more lower properties than HfO2. The energy band gap (Eg) deduced by spectroscopic ellipsometer was increased. HfAlO films was expected to improved the interface quality between channel and gate insulator. Apply to an oxide thin Film Transistors, HfAlO may help improve the properties of device.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.421.1-421.1
• /
• 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.

• 센서학회지
• /
• 제6권4호
• /
• pp.265-273
• /
• 1997

RF 마그네트론 스펏터링 방법으로 ZnO 박막을 성장시켜 TMA 가스 센서를 제작하였다. ZnO 박막의 성장분위기 가스와 첨가불순물이 박막의 표면 캐리어(전자) 농도, Hall 전자 이동도, 전기저항률 및 감도에 미치는 영향을 동작온도와 TMA 가스 농도를 변화시켜가며 조사하였다. 산소분위기에서 성장된 박막이 아르곤의 경우보다, 촉매불순물이 첨가된 박막이 첨가되지 않은 경우보다, 각각 표면 캐리어 농도와 Hall 전자 이동도가 높았고, 높은 감도 및 낮은 전기저항률을 나타내었다. 산소분위기에서 성장되었고, 불순물로 4 wt.%의 $Al_{2}O_{3}$, 1 wt.%의 $TiO_{2}$ 및 0.2 wt.%의 $V_{2}O_{3}$를 첨가한 ZnO 박막으로 만든 센서가 가장 높은 표면 캐리어 농도 $5.95{\times}10^{20}cm^{-3}$ 및 Hall 전자 이동도 $177\;cm^{2}/V{\cdot}s$와 가장 낮은 전기저항률 $0.59{\times}10^{-4}{\Omega}{\cdot}cm$ 및 가장 높은 감도 12.1을 나타내었다. 이때 TMA 가스 농도는 8 ppm, 동작온도는 $300^{\circ}C$였다.

• Corrosion Science and Technology
• /
• 제11권1호
• /
• pp.1-8
• /
• 2012

The development of martensitic grades which can be processed in continuous galvanizing lines requires the reduction of the oxides formed on the steel during the hot dip process. This reduction mechanism was investigated in detail by means of High Resolution Transmission Electron Microscopy (HR-TEM) of cross-sectional samples. Annealing of a martensitic steel in a 10% $H_2+N_2$ atmosphere with the dew point of $-35^{\circ}C$ resulted in the formation of a thin $_{C-X}MnO.SiO_{2}$ (x>1) oxide film and amorphous $_{a-X}MnO.SiO_{2}$ oxide particles on the surface. During the hot dip galvanizing in Zn-0.13%Al, the thin $_{C-X}MnO.SiO_{2}$ (x>1) oxide film was reduced by the Al. The $_{a-X}MnO.SiO_{2}$ (x<0.9) and $a-SiO_{2}$ oxides however remained embedded in the Zn coating close to the steel/coating interface. No $Fe_{2}Al_{5-X}Zn_{X}$ inhibition layer formation was observed. During hot dip galvanizing in Zn-0.20%Al, the $_{C-X}MnO.SiO_{2}$ (x>1) oxide film was also reduced and the amorphous $_{a-X}MnO.SiO_{2}$ and $a-SiO_{2}$ particles were embedded in the $Fe_{2}Al_{5-X}Zn_{X}$ inhibition layer formed at the steel/coating interface during hot dipping. The results clearly show that Al in the liquid Zn bath can reduce the crystalline $_{C-X}MnO.SiO_{2}$ (x>1) oxides but not the amorphous $_{a-X}MnO.SiO_{2}$ (x<0.9) and $a-SiO_{2}$ oxides. These oxides remain embedded in the Zn layer or in the inhibition layer, making it possible to apply a Zn or Zn-alloy coating on martensitic steel by hot dipping. The hot dipping process was also found to deteriorate the mechanical properties, independently of the Zn bath composition.

• 한국전기전자재료학회논문지
• /
• 제26권3호
• /
• pp.177-182
• /
• 2013

Transparent thin film transistors (TTFT) were fabricated on $N^+$ Si wafers. $SiO_2$, $Si_3N_4/SiO_2$ and $Al_2O_3/SiO_2$ grown on the wafers were used as gate insulators. The rf magnetron sputtered zinc tin oxide (ZTO) films were adopted as active layers. $N^+$ Si wafers were wet-oxidized to grow $SiO_2$. $Si_3N_4$ and $Al_2O_3$ films were deposited on the $SiO_2$ by plasma enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD), respectively. The mobility, $I_{on}/I_{off}$ and subthreshold swing (SS) were obtained from the transfer characteristics of TTFTs. The properties of gate insulators were analyzed by comparing the characteristics of TTFTs. The property variation of the ZTO TTFTs with time were observed.