• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.355-357
• /
• 2001

ZnO thin films were deposited on (001) sapphire substrate at various ambient gas pressure by pulsed laser deposition(PLD). Oxygen was used as ambient gas, and oxygen gas pressure was varied from 1.0${\times}$10$\^$-6/ Torr to 500 mTorr during the film deposition. As oxygen gas pressure increase in the region below critical pressure photoluminescence(PL) intensity in UV and green region increase. As oxygen gas pressure increase in the region above critical pressure photoluminescence(PL) intensity in UV and green region decrease. Each of critical ambient gas Pressures was 350 mTorr for UV emission and 200 mTorr for green emission.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제1권2호
• /
• pp.95-102
• /
• 2001

Hafnium oxide thin films for gate dielectric were deposited at $300^{\circ}C$ on p-type Si (100) substrates by plasma enhanced chemical vapor deposition (PECVD) and annealed in $O_2$ and $N_2$ ambient at various temperatures. The effect of hydrogen treatment in 4% $H_2$ at $350^{\circ}C$ for 30 min on the electrical properties of $HfO_2$for gate dielectric was investigated. The flat-band voltage shifts of $HfO_2$capacitors annealed in $O_2$ambient are larger than those in $N_2$ambient because samples annealed in high oxygen partial pressure produces the effective negative charges in films. The oxygen loss in $HfO_2$films was expected in forming gas annealed samples and decreased the excessive oxygen contents in films as-deposited and annealed in $O_2$ or $N_2$ambient. The CET of films after hydrogen forming gas anneal almost did not vary compared with that before hydrogen gas anneal. Hysteresis of $HfO_2$films abruptly decreased by hydrogen forming gas anneal because hysteresis in C-V characteristics depends on the bulk effect rather than $HfO_2$/Si interface. The lower trap densities of films annealed in $O_2$ambient than those in $N_2$were due to the composition of interfacial layer becoming closer to $SiO_2$with increasing oxygen partial pressure. Hydrogen forming gas anneal at $350^{\circ}C$ for samples annealed at various temperatures in $O_2$and $N_2$ambient plays critical role in decreasing interface trap densities at the Si/$SiO_2$ interface. However, effect of forming gas anneal was almost disappeared for samples annealed at high temperature (about $800^{\circ}C$) in $O_2$ or $N_2$ambient.

• 대한기계학회논문집
• /
• 제16권11호
• /
• pp.2159-2168
• /
• 1992

본 연구에서는 CWS 액적의 가열 및 연소에 관한 현상규명에 있어서 액적크기, CWS 석탄함량 및 연소분위기 가스온도, CWS 액적중의 미분된 석탄입자의 크기와 특히 분위기중의 산소농도의 변화에 의한 영향을 파악하고자 한다.

• 한국재료학회지
• /
• 제17권6호
• /
• pp.303-307
• /
• 2007

ZnO thin films were prepared by pulsed laser deposition on amorphous fused silica substrates at different ambient $O_2$ pressures varying from 0.5 to 500 mTorr, to observe the effect of ambient gas on their crystalline structure, morphology and optical properties. Results of X-ray diffraction, scanning electron microscopy, atomic force microscopy and photoluminescence studies showed that crystallinity, surface features and optical properties of the films significantly depended on the oxygen background pressure during growth. A low oxygen pressure (0.5 mTorr) seems to be suitable for the growth of highly c-axis oriented and smoother films possessing a superior luminescent property. The films grown at the higher $O_2$ pressures (50-500 mTorr) were found to have many defects probably due to an excessive incorporation of oxygen into ZnO lattice. We speculate that the film crystallinity could be affected by the kinetics of atomic arrangement during deposition at the higher oxygen pressures.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.362-362
• /
• 2009

$MgB_2$ bulk samples were sintered at different ambient. In this work, high purity Ar gas was added with oxygen and hydrogen gas, which can be regarded as impurity in a sense, as a possible dopant in the $MgB_2$. It was found that oxygen in the sintering ambient leads to a decrease in the critical current density $J_c$ at self field and lower fields. However, we can obtained higher $J_c$ at higher fields. It was also noted that $MgB_2$ samples sintered with 5% hydrogen in Ar revealed the increased $J_c$ at all fields compared to those processed in pure Ar ambient. From the XRD and FESEM analysis, the impurity gas in Ar can refine the $MgB_2$ grain size and result in increased grain. boundary, which can act as a strong flux pinning sites in $MgB_2$ samples. Also discussed are the effects of sintering ambient on irreversibility field, $H_{irr}$ and the upper critical field, $H_{C2}$.

• Transactions on Electrical and Electronic Materials
• /
• 제10권6호
• /
• pp.203-207
• /
• 2009

We have investigated the effect of ambient gases on the structural, electrical, and optical characteristics of ITO thin films intended for use as anode contacts in OLED (organic light emitting diodes) devices. These ITO thin films are deposited by radio frequency (RF) magnetron sputtering under different ambient gases (Ar, Ar+$O_2$, and Ar+$H_2$) at $300{^{\circ}C}$. In order to investigate the influences of the oxygen and hydrogen, the flow rate of oxygen and hydrogen in argon mixing gas has been changed from 0.5 sccm to 5 sccm and from 0.01 sccm to 0.25 sccm, respectively. The intensity of the (400) peak in the ITO thin films increased with increasing $O_2$, flow rate whilst the (400) peak was nearly invisible in an atmosphere of Ar+$H_2$. The electrical resistivity of the ITO thin films increased with increasing $O_2$ flow rate, whereas the electrical resistivity decreased sharply under an Ar+$H_2$ atmosphere and was nearly similar regardless of the $H_2$ flow rate. The change of electrical resistivity with changes in the ambient gas composition was mainly interpreted in terms of the charge carrier mobility rather than the charge carrier concentration. All the films showed an average transmittance of over 80% in the visible range. The OLED device was fabricated with different ITO substrates made with the configuration of ITO/$\alpha$-NPD/DPVB/$Alq_3$/LiF/Al in order to elucidate the performance of the ITO substrate. Current density and luminance of OLED devices with ITO thin films deposited in Ar+$H_2$ ambient gas is the highest among all the ITO thin films.

• 반도체디스플레이기술학회지
• /
• 제7권3호
• /
• pp.51-54
• /
• 2008

In this study, we investigated variations in undoped ZnO thin film properties with working pressure, $O_2$/Ar ratio, and annealing ambient. Higher vacuum pressure during deposition was observed to bring about slower growth rate resulting in samples with better crystallinity as well as hole generation efficiency through formation of shallower oxygen interstitial. Given that $O_2$/Ar ratio is greater than unity, O provided from the ambient to ZnO during annealing was found to preferably situate at interstitial sites. When He was used for the second annealing, significant changes were not observed. On the other hand, O ambient caused increased density of oxygen interstitial, thereby making the film more intrinsic-like high resistivity ZnO.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 추계학술대회 논문집
• /
• pp.117-120
• /
• 1999

The relationship between the DC degradation characteristics of the ZnO varistor and the ambient sintering-process is investigated in this study. ZnO varistors made of Matsuoka's composition were fabricated by standard ceramic techniques. The ambient sintering-process is performed at the extraordinary electrical-furnace which is equipped with the vacuum system. The Gas of sintering process was oxygen, nitrogen, argon, air respectively. The microstructure of ZnO varistors be made use of SEM equipment. The condition of DC degradation tests were conducted at $115\pm2^{\circ}C$ for periods up to 13 h. Current-voltage analysis is used to determine nonlinear coefficients($\alpha$). Resistance-frequency and capacitance-frequency analysis are accomplished to the understanding of electrical properties as DC degradation test. From above analysis, it is found that the ZnO varistor sintered in oxygen atmosphere showed superior properties at the DC degradation test.

• 한국전기전자재료학회논문지
• /
• 제25권7호
• /
• pp.543-551
• /
• 2012

In this study, transparent conducting Al-doped Zinc Oxide (AZO) films with a thickness of 150 nm were prepared on corning glass substrate by the RF magnetron sputtering with using a Al-doped zinc oxide (AZO), ($Al_2O_3$: 2 wt%) target at room temperature. This study investigated the effect of rapid thermal annealing temperature and oxygen ambient on structural, electrical and optical properties of Al-doped zinc oxide (AZO) thin films. The films were annealed at temperatures ranging from 400 to $700^{\circ}C$ by using Rapid thermal equipment in oxygen ambient. The effect of RTA treatment on the structural properties were studied by x-ray diffraction and atomic force microscopy. It is observed that the Al-doped zinc oxide (AZO) thin film annealed at $500^{\circ}C$ at 5 minute oxygen ambient gas reveals the strongest XRD emission intensity and narrowest full width at half maximum among the temperature studied. The enhanced UV emission from the film annealed at $500^{\circ}C$ at 5 minute oxygen ambient gas is attributed to the improved crystalline quality of Al-doped zinc oxide (AZO) thin film due to the effective relaxation of residual compressive stress and achieving maximum grain size.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.125.2-125.2
• /
• 2015

The evolution of oxidation states of vanadium is monitored with ambient pressure X-ray photoemission spectroscopy. As the pressure of oxygen gas and surface temperature change, the formations of various oxidation states of vanadium are observed on the surface. Under 100mTorr of the oxygen gas pressure and 523K of sample temperature, VO2 and V2O5 are formed on the surface. The temperature-dependent resistance measurement on grown sample shows a clear metal-insulator transition near 350K. In addition, the measurement of Raman spectroscopy displays the structural change from monoclinic to rutile structures across the phase transition temperature.