• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.55.2-55
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• 1998

다견정 심리판-거l르마늄(JXlly-SiGe)은 TFT(thin-film transistor)와 갇븐 소자 응용에 있어서 중요한 불칠이다 .. LPCVD (low pressure chemical vapor deposition) 방법으로 비정칠 SiGc (a-SiGe) 박막올 증 착시키고 고상결정화(SPC: solid-phase crystallization)시켜 poly-SiGc옹 얻는 것은 잘 알려져 있다. 그러 나 그러나 PF'||'&'||'pound;VD-SPC 방법올 이용한 poly-SiGc의 제조에 대해서는 아직 두드러지게 연구된 바 없다. 우리단 PF'||'&'||'pound;VD 방법으로 a-SiGc 박막올 증착시키고 고상캘정화시켜 poly-SiGc올 얻었 R며, :~ 결정성, G Gc 농도, 결정핍의 평끌 크기 눔올 XRD (x-ray diffraction) 방법으호 조사하였다. 특히 pr'||'&'||'pound;VD 증착시 가판온도,Gc 함유량 등이 고상화에 미치는 영향에 대해서 조사하였다. P PECVD 장치는 터보펌프콸 사용하여 71저진공이 2xlOlongleftarrow5 Torr에 이르렀다. 가판윤 SiOOO) 웨이퍼륜 사용하고 기판 온도는 약 150- 35()"C 사이에서 변화되었다. 증착가스는 SiH4, GcH4, 112 등흘 썼다. 증착 압력과 r.f 전력용 각각 O.25ToIT와 3W로 일정하게 하였다 .. Gc 함유량(x)은 x x=O.O-O.5 사이에서 변화되었다 .. PECVD모 증착된 SiGc 박막들은 고상결정화를 위해 $\theta$X)"(:: Nz 분위기에서 24시간동안, 혹은 5OO'C에서 4열간 가열되었다. 고상결정화 후 poly-SiGc 박막은 SiGc(Ill), (220), (311) XRD 피크들올 보여주었으며, 각 피 크들은 poly-Si에 비하여 왼쪽으로 Bragg 각이 이동되었고, Vegard’slaw에 의해서 x의 값올 확 인할 수 있었다. 이것온 RBS 결과와 열치하였다. 약 150-350'C 사이에서 변화된 기판온도의 범위 에서 증착온도가 낮올수콕 견정립의 크기는 대체로 증가하는 것으로 나타났다 .. XHD로 추정된 형 균 결정립의 크기는 최대 약 3$\alpha$1m 정도였다. 또한 같끈 샘플뜰에 대해서 기판온도가 낮올수록 증착속도가 증가함옴 확인하였다 .. Gc 함유량이 x=O.1에서 x=O.5로 증가함에 따라서도 결정립의 크기와 SiGc 증착속도는 증가하는 것으로 나타났다 .. Hwang [1] , Kim[2] 둥의 연구자들은 Gc 함유 량이 증가함에 따라 결정 립 크기가 캄소하는 것올 보고하였으냐, Tsai [3] 둥은 반대의 결과플 보 고하고 Ge 힘유량의 증가시 결정립 크기의 증가에 대해 Gc의 Si보다 낮은 융점 (melting point) 올 강조한 바 있다. 결정립 크기의 증가는 대체로 SiGe 중착속도의 증가와도 관련이 있음올 볼 때, poly-SiGc의 경우에도 polv-Si의 고상화에서와 같이 증착속도가 빠를수록 최종적언 결정럽의 크기가 커지는 것으로 이해될 수도 있다 .. PECVD 증착시 증착속도의 증가는 증착된 박딱에서의 무켈서도를 증 가시킬 수 있음올 고려하면, 이라한 결파플온 p이y-SiGc의 고상결정화에서도 ploy-Si의 고상결정 화에서와 마찬가지로 초기 박막에서의 구조직 무절서도가 클수록, 고상결정화 후 결정 립의 크기 가 커칠 수 있음올 보여준다고 생각휠 수 있다,

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.723-732
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• 1996

Cu films were deposited by chemical wapor deposition on the as-received substrates (TiN/Si) and three kinds of Cu-seeded substrates (Cu/TiN/Si) which had seeding layer in the thick ness of 5 ${\AA}$ and 130 ${\AA}$ coated by ICB(Ionized Cluster Beam) method. The effect of Cu seeding layers on the growth rate, crystallinity, grain size uniformity and film adhesion strength of final CVD-Cu films was investigated by scanning eletron microscopy(SEM), X-ray diffractometry and scratch test. The growth rate was found to incresase somewhat in the case of ICB-seeding. The XRD patterns of the Cu films on the as-received substrate and ICB Cu-seeded substrates exhibited the diffraction peaks corresponding to FCC phase, but the peak intensity ratio($I_{111}/I_{200}$) of Cu films deposited on the ICB Cu-seeded substrates increased compared with that of Cu films on the as-received substrate. The resistivity of final Cu film on 40 ${\AA}$ seeded substrate was observed as the lowest value, 2.42 $\mu\Omega\cdot$cm compared with other Cu films. In adhesion test, as the seeding thickness increased from zero to 130 ${\AA}$, the adhesion strength increased from 21N to 27N.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.5
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• pp.556-561
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• 1995

Persisent circadian rhythms in carbon assimilation, stomatal conductance and soluble carbohydrate concentration were investigated during grain filling period in rice plant transferred from a natural photoperiod to constant conditions. A weak rhythm in photosynthesis, measured as carbon assimilation, and stomatal opening, as conductance to water vapor, with a period of approximately 24-hours, occurred under constant condition. Carbon assimilation and stomatal conductance reached maximum values near noon and minimum values near midnight during the early stage (until 72-hour) after transferring to constant condition, and then the amplitude and phase were changed slowly, the rhythms with little damping, reaching maximum values near midnight and minimum values near noon during 96~120-hours after transferring. However, photosynthesis in plants grown for 14days after anthesis under constant moderate light(day and night) did not oscillated in constant condition unlike plants grown under a cycle of light and darkness. These phenomenon was observed in soluble carbohydrate concentration in flag leaves as well. Evidences from several approaches indicate that endogenous rhythms of $CO_2$ assimilation, stomatal conductance and soluble carbohydrate concentration are closely couped with each other and particularly important to plants, which depend on the natural day-night cycle as a external signal.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.474-484
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• 2005

Biological treatment is a promising alternative to conventional air pollution control methods. Bioreactors for air pollution control have found most of their success in the treatment of dilute and high flow waste air streams containing volatile organic compounds and odor compounds. They offer several advantages over traditional technologies such as incineration or adsorption. These include lower treatment costs, absence of formation of secondary pollutants, no spent chemicals, low energy demand and low temperature treatment. The most widely used bioreactor for air pollution control is biofilter, but it has several limitations. In the past years major progress has been accomplished in the development of vapor phase bioreactor, in particular biotrickling filters. Biotrickling filters are more complex than biofilters, but are usually more effective, especially for the treatment of compounds which are difficult to degrade or compounds that generate acidic by-products. While the level of understanding of biotrickling filtration process for VOCs still remains limited, the evident success of biotreatment of VOC in air stimulated the pursue of acitve research. This paper presents fundamental and theoretical/practical aspect of air pollution control in biotrickling filter. Special emphasis is given to the operating parameters and the factors influencing performance for air pollution control in biotrickling filter.

• Clean Technology
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• v.13 no.1 s.36
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• pp.1-15
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• 2007

Biological treatment is a relatively recent air pollution control technology in which off-gases containing biodegradable odors and volatile organic compounds(VOCs) are vented through microbes. It is a promising alternative to conventional air pollution control methods. Bioreactors for air pollution control have found most of their success in the treatment of dilute and high flow waste air streams containing VOCs and odor compounds. They offer several advantages over traditional technologies such as incineration or adsorption. These include lower treatment costs, absence of formation of secondary pollutants, no spent chemicals, low energy demand and low temperature treatment. The three most widely used technologies are described, namely biofiltration, biotrickling filtration, bioscrubbing. The most widely used bioreactor for air pollution control is biofilter, but it has several limitations. In the past years major progress has been accomplished in the development of vapor phase bioreaction systems, for solving problems of biofilter. Biotrickling filters are more complex than biofilters, but are usually more effective, especially for the treatment of compounds which are difficult to degrade or compounds that generate acidic by-products. This, paper reviews fundamental and theoretical/practical aspect of air pollution control in biofilter, biotrickling filter and bioscrubber, focusing more extensively on biotrickling filtration. Special emphasis is given to the operating parameters and the factors influencing performance for air pollution control, and cost estimation in biotreatment technologies.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1129-1136
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• 1999

TIN films were prepared on Si(100) substrate by ICP-CVD(inductive1y coupled plasma enhanced chemical vapor deposition) using TEMAT(tetrakis ethylmethamido titanium : Ti$[\textrm{N}\textrm{(CH)}_{3}\textrm{C}_{2}\textrm{H}_{5}]_{4}$) precursor at various deposition conditions. Phase, microstructure, and the electrical properties of TIN films were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM) and electrical measurements. Polycrystalline TiN films with B1 structure were grown at temperatures over $200^{\circ}C$. Preferentially oriented along TiN(111) films were obtained at temperatures over $300^{\circ}C$ with the flow rates of 10, 5, and 5 sccm for TEMAT, $\textrm{N}_{2}$ and Ar gas. The TiN/Si(100) interface was flat and no chemical reaction between TIN and $\textrm{SiO}_2$ was found. The resistivity, carrier concentration and the carrier mobility for the TiN sample prepared at $500^{\circ}C$ are 21 $\mu\Omega$cm, 9.5$\times\textrm{10}^{18}\textrm{cm}^{-3}$ and $462.6\textrm{cm}^{2}$/Vs, respectively.

• Korean Journal of Materials Research
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• v.8 no.5
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• pp.377-382
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• 1998

Atomic layer deposition(ALD) of amorphous TiN films on $SiO_2$ between 17$0^{\circ}C$ and 21O$^{\circ}C$ has been investigated by alternate supply of reactant sources, Ti[N($C_2,H_5,CH_3)_2]_4$ [tetrakis(ethylmethylamminoltitanium: TEMAT] and $NH_3$. Reactant sources were injected into the reactor in the order of TEMAT vapor pulse, Ar gas pulse, $NH_3$. gas pulse and Ar gas pulse. Film thickness per cycle was saturated at around 1.6 monolayer(MU per cycle with sufficient pulse times of reactant sources at 20$0^{\circ}C$. The results suggest that film thickness per cycle could be beyond 1 MLicycie in ALD, which were explained by rechemisorption mechanisms of reactant sources. The ideal linear relationship be¬tween number of cycles and film thickness is confirmed. As a results of surface limited reactions of ALD, step cover¬age was excellent. Particles caused by the gas phase reactions between TEMAT and NH3 were almost free because TEMAT was seperated from $NH_3$ by the Ar pulse. In spite of relatively low substrate temperature, carbon impurity was incorporated below 4 at%.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.249-256
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• 2006

Catalytic combustion of toluene was investigated on the Cu-Mn oxide catalysts prepared by the impregnation(Imp) and the deposition-precipitation(DP) methods. The mixing of copper and manganese has been found to enhance the activity of catalysts. It is then found that catalytic efficiency of the Cu-Mn oxide catalyst prepared by the DP method on combustion of toluene is much higher than that of the Cu-Mn oxide catalyst prepared by Imp method with the same chemical composition. The catalyst prepared by the deposition-precipitation method observed no change of toluene conversion at time on stream during 10 days and at the addition of water vapor. On the basis of catalyst characterization data, it has been suggested that the catalysts prepared by the DP method showed uniform distribution and smaller particle size on the surface of catalyst and then enhanced reduction capability of catalysts. Therefore, we think that the DP method leads on progressive capacity of catalyst and promotes stability of catalyst. It was also presumed that catalytic conversion of toluene on the Cu-Mn oxide catalyst depends on redox reaction and $Cu_{1.5}Mn_{1.5}O_4$ spinel phase acts as the major active sites of catalyst.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.3
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• pp.49-56
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• 2002

In this study, the InGaP epilayers were grown on the exact and the $2^{\circ}$, $6^{\circ}$, $10^{\circ}$ of cut GaAs substrates by metal-organic vapor phase epitaxy, and the effects of interfacial elastic strains determined by the substrate offcut angle upon the resulting dislocation density of epilayer were investigated for the first time. The elastic strains were obtained from lattice mismatch and lattice misfit by TXRD, and the dislocation densities from epilayer x-ray FWHM. For the offcut angle range used in this study, the elastic strain was maximum and x-ray FWHM minimum at offcut angle $6^{\circ}$. From 11K PL measurements, PL wavelength was found to decrease with an increase of offcut angle. PL intensity was maximum at offcut angle $6^{\circ}$. TEM results showed that the electron diffraction pattern was of typical zincblende structure, and that the dislocation density was minimum for substrate offcut angle $6^{\circ}$. The results obtained in this study, along with the device fabrication process and beam characteristics, clearly demonstrated that the optimum substrate offcut angle for the InGaP/GaAs heterostructures is $6^{\circ}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.89-94
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• 2016

In this study, the crystalline property of a-plane GaN epitaxial layer grown on r-plane sapphire by a HVPE method has been investigated according to the V/III ratio and the growth time of multi-step growth. Furthermore, these results were compared with the previous result obtained from the single-step growth of a-plane GaN on r-plane sapphire substrate. In the multi-step growth for a-plane GaN epitaxial layer on r-plane sapphire, the FWHM values of rocking curve in GaN epitaxial layer were decreased as the HCl source flow rate and the growth time were increased. The void formed in epitaxial layer was continuously decreased as the growth time in first step and second step using a higher HCl flow rate was increased. As a result, the GaN layer obtained with the longest growth time on the first step and second step exhibited the lowest FWHM values of 584 arcsec and the smallest dependence of azimuth angle.