• Electrical & Electronic Materials
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• v.9 no.8
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• pp.819-824
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• 1996

We have investigated the temperature dependence of CO gas sensitivity for ZnO and ZnO-CuO thick films at 200 ppm CO gas, where those films were prepared by thermal transformation. The ZnO thick film shows the maximum sensitivity of -4 at >$300^{\circ}C$ On the other hand, ZnO-CuO(more than 1mol%) thick film shows that the maximum sensitivity reduced to less than 1.5. The decrease in sensitivity of CO gas with increasing the CuO contents is due to the decrease of the oxygen absorption in thick films.

• Electrical & Electronic Materials
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• v.9 no.9
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• pp.925-932
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• 1996

Using the d.c. 2-probe method, we have examined the temperature dependence of CO gas sensitivity of pure ZnO and ZnO CuO thick films prepared by the acqueous precipitation. At 200ppm CO gas, pure ZnO thick film shows the maximum sensitivity of -6.5 at 300.deg. C. On the other hand, the maximum sensitivity of 1-5 mol% and 10-15 mol% CuO added ZnO thick films are 2.8-2.5 and 1.6, respectively. Therefore, the sensitivity of pure ZnO thick film is about three times larger than those of ZnO-CuO thick films. We suggest that the promotion of maximum sensitivity is caused by low packing and the increase of chemical adsorptions for $O_{2}$ gas.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.724-727
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• 2009

We have fabricated (Ba,Sr)TiO3$TiO_3$ thick films doped with various amount of ZnBO dopants (1, 3, and 5 wt%) by screen printing method on the alumina substrates, which were sintered at the temperature below $1200^{\circ}C$. With increasing the amount of ZnBO dopants, the relative dielectric permittivity of ZnBO doped (Ba,Sr)$TiO_3$ was decreased, while loss tangent was increased. 1 wt% ZnBO doped (Ba,Sr)$TiO_3$ thick film has relative dielectric permittivity of 759 at 1 MHz, while 3 and 5 wt% of ZnBO doped (Ba,Sr)$TiO_3$ thick films have 624 and 554, respectively. By introducing ZnBO dopants to the (Ba,Sr)$TiO_3$ thick films, leakage current densities were decreased. The decreased leakage current with increasing ZnBO dopants can be explained by increased density and grain size of thick film on alumina substrate. We believe this decreased leakage current density probably come from the increased grain size and increased density.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.749-753
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• 2006

The $ZnGa_2O_4$ phosphor thick films were fabricated using a screen printing method on Si(100) substrates at various sintering temperatures. The XRD patterns show that the $ZnGa_2O_4$ thick films have a (311) main peak and a spinel structure with increasing sintering temperatures. The particle sizes of $ZnGa_2O_4$ phosphor were about 100 nm and the thickness of $ZnGa_2O_4$ thick film was $10{\mu}m$. The CL and PL properties of $ZnGa_2O_4$ showed main peak of 420nm and maximum intensity at the sintering temperature of $900^{\circ}C$. These results indicate that $ZnGa_2O_4$ phosphor thick films hold promise for displays such as plasma display panel and field emission display.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.245-248
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• 1991

Recently, oxide semiconductor gas sensors consisted of n-type semiconductor materials such as $SnO_2$, ZnO and $Fe_2O_3$ have been widely used to detect reducing gases. In this paper, we made the thick-film ZnO gas sensors with $PdCl_2$ as a catalyst and investigated the sensitivity to CO gas. In the thick-film Zno sensor, the highest sensitivity was shown in the sensor with 1wt.% of $PdCl_2$ which was sintered for 1 hour at $700^{\circ}C$ and operated at $300^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.5
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• pp.355-358
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• 2011

As a II-IV compound semiconductor, ZnO has a wide band gap of 3.37 eV with transparent properties. Due to this transparent properties, ZnO materials can be also employed as the transparent conducting electrode materials. Recently, rapid progress has been made in the field of DSSC (dye sensitized solar cell)area. Therefore, strong demands have been required for the transparent electrodes with low temperature processing and cheap cost. In this paper, we will prepare ZnO thick films on the PET substrates for the electrode applications. We will investigate the structural and microstructure properties through the XRD, and SEM analysis, respectively. Also, we will study the electrical of specimens to apply the conducting electrode.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.467-473
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• 2010

The objective of this study is to prepare lead-free thick film resistor (TFR) paste compatible with AlN substrate for hybrid microelectronics. For this purpose, CaO-ZnO-$B_2O_3-Al_2O_3-SiO_2$ glass system was chosen as a sintering aid of $RuO_2$. The effects of the weight ratio of CaO to ZnO in glass composition, the glass content and the sintering temperature on the electrical properties of TFR were investigated. $RuO_2$ as a conductive and glass powder were dispersed in an organic binder to obtain printable paste and then thick-film was formed by screen printing, followed by sintering at the range between $750^{\circ}C$ and $900^{\circ}C$ for 10 min with a heating rate of $50^{\circ}C$/min in an ambient atmosphere. The addition of ZnO to glass composition and sintering at higher temperature resulted in increasing sheet resistance and decreasing temperature coefficient of resistance. Using $RuO_2$-based resistor paste containing 40 wt%glass of CaO-20.5%ZnO-25%$B_2O_3$-7%$Al_2O_3$-15%$SiO_2$ composition, it is possible to produce thick film resistor on AlN substrate with sheet resistance of $10.6\Omega/\spuare$ and the temperature coefficient of resistance of 702ppm/$^{\circ}C$ after sintering at $850^{\circ}C$.

• Journal of Surface Science and Engineering
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• v.42 no.5
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• pp.216-219
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• 2009

A surface acoustic wave (SAW) filter structure was fabricated employing $4{\mu}m$ thick nanocrystalline diamond (NCD) and $2.2{\mu}m$ thick ZnO films on Si wafer. The NCD film was deposited in an $Ar/CH_4$ gas mixture by microwave plasma chemical vapor deposition method. The ZnO film was formed over the NCD film in an RF magnetron sputter using ZnO target and $Ar/O_2$ gas. On the top of the two layers, copper film was deposited by the RF sputter and inter digital transducer (IDT) electrode pattern (line/space : $1.5/1.5{\mu}m$) was defined by the photolithography including a lift-off etching process. The fabricated SAW filter exhibited the center frequency of 1.66 GHz and the phase velocity of 9,960 m/s, which demonstrated that a giga Hertz SAW filter can be realized by utilizing the nanocrystalline diamond thin film.

• Korean Journal of Materials Research
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• v.12 no.4
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• pp.304-307
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• 2002

A zinc oxide (ZnO) single crystal was used as a substrate in the hydride vapor-phase epitaxy (HVPE) growth of GaN and the structural and optical properties of GaN layer were characterized by x- ray diffraction, transmission electron microscopy, secondary ion mass spectrometry, and photoluminescence (PL) analysis. Despite a good lattice match and an identical structure, ZnO is not an appropriate substrate for application of HVPE growth of GaN. Thick film could not be grown. The substrate reacted with process gases and Ga, being unstable at high temperatures. The crystallinity of ZnO substrate deteriorated seriously with growth time, and a thin alloy layer formed at the growth interface due to the reaction between ZnO and GaN. The PL from a GaN layer demonstrated the impurity contamination during growth possibly due to the out-diffusion from the substrate.

• Journal of IKEEE
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• v.23 no.2
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• pp.375-379
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• 2019

$ZnO-SnO_2(ZTO)$ was deposited by RF magnetron sputtering using a ceramic target whose Zn atomic ratio to Sn is 2:1 as a target, and the crystal structure variation with thermal treats was investigated. Transparent thin film transistors (TTFT) were fabricated using the ZTO films as active layers. About 100 nm-thick $Si_3N_4$ film grown on 100 nm-thick $SiO_2$ film was adopted as gate dielectrics. The mobility, threshold voltage, $I_{on}/I_{off}$, and interface trap density were obtained from the transfer characteristics of ZTO TTFTs. The effects of substrate temperature, and post-annealing on the property variation of ZTO TTFT were analyzed.