• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.2
• /
• pp.91-95
• /
• 2012

ZnO thin films were deposited on p-type 4H-SiC substrate by pulsed laser deposition. ZnO nanowires were formed on p-type 4H-SiC substrate by furnace. Ti/Au electrodes were deposited on ZnO thin film/SiC and ZnO nanowire/SiC structures, respectively. Structural and crystallographical properties of the fabricated ZnO thin film/SiC and ZnO nanowire/SiC structures were investigated by field emission scanning electron microscope and X-ray diffraction. In this work, resistance and sensitivity of ZnO thin film/SiC gas sensor and ZnO nanowire/SiC gas sensor were measured at $300^{\circ}C$ with various CO gas concentrations (0%, 90%, 70%, and 50%). Resistance of gas sensor decreases at CO gas atmosphere. Sensitivity of ZnO nanowire/SiC gas sensor is twice as big as sensitivity of ZnO thin film/SiC gas sensor.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.123-124
• /
• 2011

플라즈마 화학적 기상 증착(plasma enhanced chemical vapor deposition)공정 중 NH3 gas flow rate, RF power, SiH4 gas flow rate을 고정시키고 N2O gas flow rate을 0 sccm부터 250 sccm까지 변화시키는 조건 하에 SiON박막을 증착한 후 그 투과율, 굴절률을 측정하고 분석하였다. N2O gas flow rate조건별 시편들은 증착율을 계산하여 350 nm 두께로 동일하게 SiON을 증착하였고, borofloat위에 SiON을 증착한 샘플은 투과율을, 실리콘기판 위에 SiON을 증착한 샘플로는 굴절률을 측정하였다. 투과율의 경우는 UV/Vis spectrometer를 이용해 633 nm, 1550 nm 두 가지 파장 대 모두에서 N2O gas flow rate이 가장 큰 250 sccm일 때 가장 높은 것을 알 수 있었고 N2O gas flow rate이 낮아질수록 투과율 또한 작아지는 경향을 보였다. 굴절률은 ellipsometer를 이용해 측정하였으며 633 nm 파장에서 N2O gas flow rate가 가장 낮은 0 sccm일 때 굴절률이 가장 큰 값을 가지고 N2O gas flow rate이 커질수록 굴절률은 지수함수적으로 감소되었다(n=1.837~1.494). 이는 N2O gas flow rate이 낮을수록 SiN계열에 커질수록 SiO2계열에 가까워지는 현상으로 이해된다. 이러한 실험분석 결과는 향후 실리카 도파로의 설계 및 최적화를 위해 사용될 수 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.12
• /
• pp.1028-1032
• /
• 2009

In this study, the influences of silicon-based gas barrier films fabricated by using a facing target sputtering(FTS) system on the gas permeability for flexible displays have been investigated. Under these optimum conditions on the $SiO_x$ film with oxygen concentration($O_2/Ar+O_2$) of 3.3% and the $SiO_xN_y$ film with nitrogen concentration($N_2/Ar+O_2+N_2$) of 30% deposited by the FTS system, it was found that the films were grown about 4 times higher deposition rate than that of the conventional sputtering system and showed high transmittance about 85% in the visible light range. Particularly, the polyethylene naphthalate(PEN) substrates with the $SiO_x$ and/or $SiO_xN_y$ films showed the enhanced properties of decreased water vapor transmission rate (WVTR) over $10^{-1}\;g/m^2{\cdot}day$ compared with the PEN substrate without any gas barrier films, which was due to high packing density in the Si-based films with high plasma density by FTS process and/or the denser chemical structure of Si-N bond in the $SiO_xN_y$ film.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.1
• /
• pp.83-86
• /
• 2004

A high temperature tolerant microelectronic-based carbon monioxde(CO) gas sensor has been developed. The gas sensing performance has been studied over a wide temperature range$(100-300^\circ{C)}$. The gas sensitivity of the sensor is high, its initial sensing behavior is very fast, and the sensor is reproducible. Pt-SiC and $Pt-SnO_2-SiC$ diodes are fabricated using standard semiconductor processes and their CO gas-sensing behaviors are analyzed as a function of CO gas concentration and temperature by I-V and $\Delta{I-t}$ methods under steady-state and transient conditions. The sensitivity of the device with $Pt-SnO_2$ catalytic gate is higher than that of the Pt gate. The experimental results indicate that $SnO_2$ layer improves the catalytic reaction of the Pt layer.

• Journal of the Korean institute of surface engineering
• /
• v.43 no.1
• /
• pp.36-40
• /
• 2010

The SiO vapor that was generated from a mixture of Si and $SiO_2$ was reacted at $1350^{\circ}C$ for 2 h under vacuum with carbon nanofibers to produce SiC nanofibers having an average diameter of 100~200 nm. In order to understand the gas corrosion behavior, SiC nanofibers were exposed to air up to $1000^{\circ}C$. SiC oxidized to amorphous $SiO_2$, but its oxidation resistance was inferior unlike bulk SiC, because of high surface area of nanofibers. When SiC nanofibers were exposed to Ar-1% $SO_2$ atmosphere, SiC oxidized to amorphous $SiO_2$, without forming $SiS_2$, owing to the thermodynamic stability of $SiO_2$.

• Journal of the Korean Ceramic Society
• /
• v.28 no.8
• /
• pp.625-625
• /
• 1991

The specimens for the corrosion test were made by hot-pressing of SiC power with 2 wt% Nl2O3 and 10wt% Al2O3 additions at 2000℃ and 2050℃. The specimens were corroded in 37 mole% NaCl and 63 mole% Na2SO4 salt mixture at 1000℃ up to 60 min. SiO2 layer was formed on SiC and then this oxide layer was dissolved by Na2O ion in the salt mixture. The rate of corrosion of the specimen containing 10 wt% Al2O3 was slower than that of the specimen containing 2 wt% Al2O3. This is due to the presence of continuous grain boundary phase in the specimen containing 10 wt% Al2O3. The oxidation of SiC produced gas bubbles at the SiC-SiO2 interface. The rate of corrosion follows a linear rate law up to 50 min. and then was accelerated. This acceleration is due to the disruption oxide layer by the gas evolution at SiC-SiO2 interface. Pitting corrosion has found at open pores and grain boundaries.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.4
• /
• pp.288-292
• /
• 1998

In this paper, we fabricated $SnO_2$ composite ceramics doped with 0~20mol% $SnO_2$ of bulk type to investigate the CO and $H_2$ gas sensitivity in various composition, temperature, and concentration of CO and $H_2$ gas. At the temperature range from $100^{\circ}C\sim425^{\circ}C$, the measured 1000ppm and 250ppm CO gas sensitivities of $SiO_2-SnO_2$composite ceramics were about 1.0~7.6 and 1.0~5.6, respectively. These values were about 1.0~1.5 times larger than pure $SnO_2$. The maximum 1000ppm CO gas sensitivity of $SiO_2-SnO_2$composites were measured around $325^{\circ}C$. At the temperature range from $270^{\circ}C\sim380^{\circ}C$, the 1000ppm and 500ppm $H_2$gas sensitivities of $SiO_2-SnO_2$ composites were about 2.9~21.2 and 2.1~11.3, respectively. Also the maximum 1000, 500 ppm $H_2$ gas sensitivities of samples were measured around.

• Korean Journal of Materials Research
• /
• v.14 no.3
• /
• pp.175-180
• /
• 2004

SiC nanotubes were synthesized by CNT-confined reaction. Evaporated SiO gas reacted with carbon nanotubes by VS growth mechanism. By confineded reaction, carbon nanotube was changed to SiC nanotube, and synthesized SiC nanotube was filled partly by the gas reaction in the nanotubes. SiC nanotube's mean diameters were not changed than carbon nanotubes because of means ratio of $CO_2$ and SiO gas was maintained evenly during the process. This result was same of data of simulation. By TEM observastion, SiC nanotube was filled by reaction of inner wall of CNT and SiO gas through the VS reactions. Converted SiC nanotube's compositions were revealed Si and C of 1: 1 ratios at all sites of nanotube by EDS.

• Journal of the Semiconductor & Display Technology
• /
• v.22 no.2
• /
• pp.35-39
• /
• 2023

Silicon oxide thin films have been deposited by plasma-enhanced chemical vapor deposition in SiH4 and N2O plasma along the variation of the gas flow ratio. Optical emission spectroscopy was employed to monitor the plasma and ellipsometry was employed to obtain refractive index of the deposited thin film. The atomic ratio of Si, O, and N in the film was obtained using XPS depth profiling. Fourier Transform Infrared Spectroscopy was used to analyze structures of the films. RI decreased with the increase in N2O/SiH4 gas flow ratio. We noticed the increase in the Si-O-Si bond angles as the N2O/SiH4 gas flow ratio increased, according to the analysis of the Si-O-Si stretching peak between 950 and 1,150 cm-1 in the wavenumber. We observed a correlation between the optical emission intensity ratio of (ISi+ISiH)/IO. The OES intensity ratio is also related with the measured refractive index and chemical composition ratio of the deposited thin film. Therefore, we report the added value of OES data analysis from the plasma related to the thin film characteristics in the PECVD process.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.7
• /
• pp.1-6
• /
• 2000

In this study, the effects of the addition of $N_2$ gas into the $Cl_2$ (90)/Ar(10) gas mixture, which has been proposed as the optimized etching gas combination, for etching of platinum was performed. The selectivity of platinum film to $SiO_2$ film etch mask increased with the addition of $N_2$ gas, and etch profile over 75 $^{\circ}$ could be obtained when 20 % additive $N_2$ gas was added. These phenomena were interpreted as the results of a formation of blocking layer such as Si-N or Si-O-N on the $SiO_2$ mask. The maximum etch rate of Pt film and selectivity of Pt to $SiO_2$ are 1425 ${\AA}$/min and 1.71, respectively. These improvements were considered to be due to the formation of more volatile compounds such as Pt-N or Pt-N-Cl.