• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.126-129
• /
• 2001

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process ws performed by pulsed laser deposition (PLD). The p-n junction was formed and showed a typical I-V characteristic. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.

• The Korean Journal of Ecology
• /
• v.15 no.4
• /
• pp.355-363
• /
• 1992

Nitrate reductase activity(NRA) and induced NRA were compared in 4 species of moss ctenidium molluscum, homalothecium, tortella tortusa and neckera crispa collected from limestone in england. the NRA and dry weight of the c. molluscum were also measured after spraying with acidic deposition adjusted to ph 5.6, 4.6, 3.6 and 2.8 with one of two molar ratios of nitric to sulfuric acid, i.e. 1:0(N alone) and 1:2(1N+2S) for 20 days. All 4 species showed high NR leavels in the upper part of cut shoots and occurred maximum inducation of NRA within 6h. c. molluscum had the highest NRA levels among 4 species. after daily spraying of acidic deposition, NRA of c. molluscum was increased much more largely at ph 6 and ph 3.6 derived from N alone than from 1N+2S. However that was decreased at ph 2.8 derived both from N alone and 1N+2S . Decline of dry weight had occurred at ph 3.6 and 2.8 derived both from N alone and 1N+2S. Whereas substantial fertilization effect was observed at ph 4.6 derived from N alone. the data suggest that c. molluscum are able to utilize nitrate more effectivery than any other species, and NRA induction are more sensitive than growth response to nitrogen content of acidicdeposition in a short- term. however toxic effects was detected at high $NO_3$ supply and low phacidic deposition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.04a
• /
• pp.54-55
• /
• 2006

Organic light-emitting diodes(OLEOs) are attractive because of possible application in display with low operating voltage, low power consumption, self-emission and capability of multicolor emission by the selection of emissive material. We investigated the effects of deposition rate on the electrical characteristics, physical characteristics and optical characteristics of OLEOs in the ITO(indium-tin-oxide)/N.N'-diphenyl-N,N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline)aluminum($Alq_3$)/Al device. We measured current density, luminous flux and luminance characteristics of devices with varying deposition rates of TPD and $Alq_3$. It has been found that optimal deposition rate of TPD and $Alq_3$ were respectively $1.5{\AA}/s$ from the device structure. An AFM measurement results, surface roughness of the deposited film was the lowest when deposition rate was $1.5{\AA}/s$.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2001.06a
• /
• pp.6-7
• /
• 2001

• Journal of Ecology and Environment
• /
• v.29 no.3
• /
• pp.305-321
• /
• 2006

Atmospheric Acid Deposition: Nitrogen Saturation of Forests: Volume weighted annual average wet deposition of nitroge at 33 sites in Korea during 1999-2004 ranged 7.28 to $21.05kgN{\cdot}ha^{-1}{\cdot}yr^{-1}$ with average $12.78kgN{\cdot}ha^{-1}{\cdot}yr^{-1}$, which values are similar level with nitrogen deposition of Europe and North America. The temperate forests that suffered long-term high atmospheric nitrogen deposition are gradually saturated with nitrogen. Such nitrogen saturated forest watersheds usually leach nitrate ion ($NO_3^-$) in stream water and soil solution. It may be likely that Korean forest ecosystems are saturated by much nitrogen deposition. In leaves with nitrogen saturation ratios of N/P, N/K and N/Mg are so enhanced that mineral nutrient system is disturbed, suffered easily frost damage and blight disease, reduced fine-root vitality and mycorrhizal activity. Consequently nitrogen saturated forests decrease primary productivity and finally become forest decline. Futhermore understory species are replaced the nitrophobous species by the nitrophilous one. In soil with nitrogen saturation uptake of methane ($CH_4$) is reduced and emission of nitrogen monoxide (NO) and nitrous oxide ($N_{2}O$) are increased, which gases are greenhouse gas accelerating global warming.

• Journal of the Korean Ceramic Society
• /
• v.39 no.6
• /
• pp.594-597
• /
• 2002

Silicon Oxynitride(SiON) thick films on p-type silicon(100) wafers have obtained by using plasma-enhanced chemical vapor deposition from SiH$_4$ , N$_2$O and N$_2$. Prism coupler measurements show that the refractive indices of SiON layers range from 1.4620 to 1.5312. A high deposition power of 180 W leads to deposition rates of up to 5.92${\mu}$m/h. The influence of the deposition condition on the chemical composition was investigated using X-ray photoelectron spectroscopy. After deposition of the SiON thick films, the films were annealed at 1050$^{\circ}C$ in a nitrogen atmosphere for 2 h to remove absorption band near 1.5${\mu}$m.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1243-1245
• /
• 1994

SiN films were deposited in $Si_2H_6$(99.9%), $NH_3$(99.99%) gas mixture with carrier gas $N_2$ on Si substrate by ArF Excimer Laser CVD. SiN film deposition conditions that are substrate temperature and Laser average power were varied in order to investigate the dependence of SiN film on the condition. A post-deposition anneal was performed to examine variation of fixed charge density in the films. The deposition rate was increased as the substrate temperature and Laser power were increased during film deposition. The refractive index was increased with increasing substrate temperature, but it didn't have the dependence on Laser power. The fixed charge density was decreased when a post-deposition anneal was performed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.7 no.1
• /
• pp.67-74
• /
• 2008

In this paper, the surface characteristics of the AIP-TiN coated of the SKH51 and SKD11 steels under various deposition times are presented with emphasis on the comparison of the two materials. The micro-particle, the surface roughness, the micro-hardness, the coated layer thickness, the atomic distribution of Ti, N and Fe elements and the adhesion are measured for various deposition times. It has been shown that the micro-particle, the surface roughness, the coated layer thickness and the atomic distribution of Ti, N and Fe elements are similar for the two cases regardless of the test deposition time from 10 to 180 minutes. However, it has been shown that the micro-hardness and the adhesion of the SKH51 steel are higher than the SKD11 steel, indicating that they are much affected by the hardness of the material to be coated.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.204-205
• /
• 2011

In thin film silicon solar cells, p-i-n structure is adopted instead of p/n junction structure as in wafer-based Si solar cells. PECVD is a most widely used thin film deposition process for a-Si:H or ${\mu}c$-Si:H solar cells. For best performance of thin film silicon solar cell, the dopant profiles at p/i and i/n interfaces need to be as sharp as possible. The sharpness of dopant profiles can easily achieved when using multi-chamber PECVD equipment, in which each layer is deposited in separate chamber. However, in a single-chamber PECVD system, doped and intrinsic layers are deposited in one plasma chamber, which inevitably impedes sharp dopant profiles at the interfaces due to the contamination from previous deposition process. The cross-contamination between layers is a serious drawback of a single-chamber PECVD system in spite of the advantage of lower initial investment cost for the equipment. In order to resolve the cross-contamination problem in single-chamber PECVD systems, flushing method of the chamber with NH3 gas or water vapor after doped layer deposition process has been used. In this study, a new plasma process to solve the cross-contamination problem in a single-chamber PECVD system was suggested. A single-chamber VHF-PECVD system was used for superstrate type p-i-n a-Si:H solar cell manufacturing on Asahi-type U FTO glass. A 80 MHz and 20 watts of pulsed RF power was applied to the parallel plate RF cathode at the frequency of 10 kHz and 80% duty ratio. A mixture gas of Ar, H2 and SiH4 was used for i-layer deposition and the deposition pressure was 0.4 Torr. For p and n layer deposition, B2H6 and PH3 was used as doping gas, respectively. The deposition temperature was $250^{\circ}C$ and the total p-i-n layer thickness was about $3500{\AA}$. In order to remove the deposited B inside of the vacuum chamber during p-layer deposition, a high pulsed RF power of about 80 W was applied right after p-layer deposition without SiH4 gas, which is followed by i-layer and n-layer deposition. Finally, Ag was deposited as top electrode. The best initial solar cell efficiency of 9.5 % for test cell area of 0.2 $cm^2$ could be achieved by applying the in-situ plasma cleaning method. The dependence on RF power and treatment time was investigated along with the SIMS analysis of the p-i interface for boron profiles.

• Journal of the Korean Society for Heat Treatment
• /
• v.5 no.1
• /
• pp.1-12
• /
• 1992

In order to improve adhesive force of TiN film, we sputtered titanium as interlayer before TiN deposition by Plasma Enhanced Chemical Vapour Deposition. We observed changes of hardness and adhesion at a various thickness of titanium interlayer and also examined analysis. At the critical thickness of the titanium interlayer(about $0.2{\mu}$), adhesive force of TiN films were promoted mostly. But over the critical thickness, a marked reduction of adhesive force was showed, because of the internal stress of titanium interlayer. From AES analysis, the adhesion improvement of TiN films was mainly caused by nitrogen diffusion into titanium interlayer during TiN deposition process which relieved stress concentration at TiN coating-substrate interface.