• Korean Journal of Materials Research
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• v.23 no.9
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• pp.477-482
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• 2013

We investigated the detection properties of nitrogen monoxide (NO) gas using transparent p-type $CuAlO_2$ thin film gas sensors. The $CuAlO_2$ film was fabricated on an indium tin oxide (ITO)/glass substrate by pulsed laser deposition (PLD), and then the transparent p-type $CuAlO_2$ active layer was formed by annealing. Structural and optical characterizations revealed that the transparent p-type $CuAlO_2$ layer with a thickness of around 200 nm had a non-crystalline structure, showing a quite flat surface and a high transparency above 65 % in the range of visible light. From the NO gas sensing measurements, it was found that the transparent p-type $CuAlO_2$ thin film gas sensors exhibited the maximum sensitivity to NO gas in dry air at an operating temperature of $180^{\circ}C$. We also found that these $CuAlO_2$ thin film gas sensors showed reversible and reliable electrical resistance-response to NO gas in the operating temperature range. These results indicate that the transparent p-type semiconductor $CuAlO_2$ thin films are very promising for application as sensing materials for gas sensors, in particular, various types of transparent p-n junction gas sensors. Also, these transparent p-type semiconductor $CuAlO_2$ thin films could be combined with an n-type oxide semiconductor to fabricate p-n heterojunction oxide semiconductor gas sensors.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.13-16
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• 2012

Zinc oxide (ZnO) films were deposited by an RF magnetron sputtering system with the RF power of 200W and 300W and flow rate of oxygen gases of 20 and 30 sccm, in order to research the growth of ZnO on carbon doped silicon oxide (SiOC) thin film. The reflectance of SiOC film on Si film deposited by the sputtering decreased with increasing the oxygen flow rate in the range of long wavelength. In comparison between ZnO/Si and ZnO/SiOC/Si thin film, the reflectance of ZnO/SiOC/Si film was inversed that of ZnO/Si film in the rage of 200~1000 nm. The transmittance of ZnO film increased with increasing the oxygen gas flow rate because of the transition from conduction band to oxygen interstitial band due to the oxygen interstitial (Oi) sites. The low reflectance and the high transmittance of ZnO film was suitable properties to use for the front electrode in the display or solar cell.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.124-124
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• 2003

To improve the electrochemical properties of thin-film LiCoO$_2$ cathodes, metal oxides were coated on the LiCoO$_2$ thin films using f sputtering. Galvanostatic charge-discharge experiments showed the enhanced cycling behaviors in the metal-oxide coated LiCoO$_2$ thin films than the uncoated ones. These results are because the metal-oxide coating layer suppresses the degradation of Li-diffusion kinetics during cycling, which is related to the protection of cathode surface from the electrolytes [l-3]. The variation in the metal-oxide coating thickness ranging from 10 to 300 nm did not affect the electrochemical properties. Changes of lattice constants in the coated and bare LiCoO$_2$ thin films at different charged states will also be discussed.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.114-118
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• 1989

Due to the increased integration density of VLSI circuits a highly reliable thin oxide film is required to fabricate a small geometry MOS device. The behavior of thermal $SiO_2$ under high electric field and current condition has a major effect on MOS device degration and also the practical use of MOS device under irradiation has cause the degration of thin oxide films. In this paper, in order to evaluate the reliability of thin oxides with no stress applied and stressed by the irradiation under low electric field, the tests of TDDB (Time-dependent-dielectric breakdown) are used. Failure times against electric field are examined and acceleration factor is obtained for each case. Based on the experimental data, breakdown wear out limitation for thin oxide films is characterised.

• Journal of Sensor Science and Technology
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• v.16 no.3
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• pp.229-233
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• 2007

The indium tin oxide (ITO) films were deposited on CR39 substrate using DC magnetron sputtering. The ITO thin films deposited at room temperature because CR39 substrate its glass-transition temperature is $130^{\circ}C$. The ITO thin films used bottom and top electrode and for organic thin film transparent transistors (OTFTs). The ITO thin film electrodes electrical properties and optical transparency properties in the visible wavelength range (300-800 nm) strongly dependent on volume of oxygen percent. For the optimum resistivity and transparency of the ITO thin film electrode achieved with a 75 W plasma power, 10 % volume of oxygen and a 27 nm/min deposition rate. Above 85 % transparency in the visible wavelength range (300-800 nm) measured without post annealing process and a low resistivity value $9.83{\times}10^{-4}{\Omega}cm$ was measured thickness of 300 nm. All fabrication process of ITO thin films did not exceed $80^{\circ}C$.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.414-418
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• 1999

Typical metal oxide thin films having optical and electrical properties are widely used as inorganic functional materials. Liquid phase deposition(LPD) method, a new low temperature process, has been developed for the several advantages of no vacuum system, low cost, high throughput, and low processing temperature(<$50^{\circ}C$). Silica powder was added to 40wt% hydrofluoro-silicic acid($H_2$SiF\ulcorner) to obtain an immersing solution of silica-saturated hydrofluorosilicic acid solution. Boric acid solution was continuously added in the range from 0 to 0.05M to prepare supersaturated hydrofluorosilicic acid solution. LPD $SiL_2$film was formed with the variation of added amount of $H_2$O. The SiO$_2$thin film could be prepared from hydrofluorosilicic acid by LPD method. The thickness of LPD $_SiO2$film was influenced by the boric acid concentration and added amount of $H_2$O. Silicon in thin film existed as SiF\ulcorner by Raman spectrum.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.106-106
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• 2011

Recently, zinc oxide (ZnO) thin films have attracted great attention as a promising candidate for various electronic applications such as transparent electrodes, thin film transistors, and optoelectronic devices. ZnO thin films have a wide band gap energy of 3.37 eV and transparency in visible region. Moreover, ZnO thin films can be deposited in a poly-crystalline form even at room temperature, extending the choice of substrates including even plastics. Therefore, it is possible to realize thin film transistors by using ZnO thin films as the active channel layer. In this work, we investigated influence of oxygen partial pressure on ZnO thin films and fabricated ZnO-based thin film transistors. ZnO thin films were deposited on glass substrates by using a pulsed laser deposition technique in various oxygen partial pressures from 20 to 100 mTorr at room temperature. X-ray diffraction (XRD), transmission line method (TLM), and UV-Vis spectroscopy were employed to study the structural, electrical, and optical properties of the ZnO thin films. As a result, 80 mTorr was optimal condition for active layer of thin film transistors, since the active layer of thin film transistors needs high resistivity to achieve low off-current and high on-off ratio. The fabricated ZnO-based thin film transistors operated in the enhancement mode with high field effect mobility and low threshold voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.7
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• pp.433-437
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• 2014

Transparent thin film transistors were fabricated on $n^+$-Si wafers coated by $Al_2O_3/SiO_2$. Zinc tin oxide (ZTO) films deposited by rf magnetron sputtering were employed for active layers. The mobility (${\mu}s$), threshold voltage ($V_T$), and subthreshold swing (SS) dependances on ZTO thickness were analyzed. The $V_T$ decreased with increasing ZTO thickness. The ${\mu}s$ raised from $5.1cm^2/Vsec$ to $27.0cm^2/Vsec$ by increasing ZTO thickness from 7 nm to 12 nm, and then decreased with ZTO thickness above 12 nm. The SS was proportional to ZTO thickness.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.3
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• pp.154-159
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• 2015

In this paper, we propose a numerical method to model temperature dependent threshold voltage shift observed in metal oxide thin-film transistors (TFTs). The proposed model is then implemented in AIM-SPICE circuit simulation tool. The proposed method consists of modeling the well-known stretched-exponential time dependent threshold voltage shift and their temperature dependent coefficients. The outputs from AIM-SPICE tool and the stretched-exponential model at different temperatures in the literature are compared and they show a good agreement. Since metal oxide TFTs are the promising candidate for flat panel displays, the proposed method will be a good stepping stone to help enhance reliability of fast-evolving display circuits.

• 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.