• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.92-92
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• 1999

양자우물 무질서화 기술은 양자우물구조의 성장후 그 구조의 밴드갭을 국부적으로 변화시킬 수 있는 기술적 특성으로 인해 기존의 광기능 소자 제작을 위한 결정재성장방법을 대체 혹은 보완할 수 있는 장점이 있기 때문에 최근 활발히 연구되고 있다. 여러 가지 양자우물 무질서화공정중 유전체 박막을 사용하는 impurity free vacancy disordering (IFVD) 공정은 불순물이 개입하지 않는 공정으로 공정후 양질의 반도체 표면을 유지할 수 있는 장점이 있으며 고아소자 제작시 광손실의 증가를 초래하지 않는다. 이 공정은 vacancy의 source로 작용하는 유전체박막의 특성에 크게 의존하며 GaAs/AlGaAs 계열의 양자우물에서는 많은 연구가 진행되었으나, 광통신용 광소자의 제작에 사용되는 InGaAs/InGaAsP 계열의 양자우물에 대한 연구는 충분하지 않다. 그림 1은 IFVD를 위해 본 연구에서 사용된 CBE로 성장한 InGaAs/InGaAsP SQW 구조이다. 성장된 구조는 상온에서의 QW peak, λpl=1550nm 이었다. IFVD를 위한 유전체 덮개층으로는 PECVD로 성장 조정하여 박막성장시의 조건을 변화시킴으로써 유전체 덮개층 박막의 특성을 변화시켰다. 그림 2는 질소 분위기의 furnace에서 75$0^{\circ}C$로 8분간 IFVD를 수행한후 측정한 무질서화된 양자우물의 상온 PL spectrum을 보여준다. 그림에서 보는바와 같이 동일한 SiNx 덮개층을 사용하는 경우에도 적어도 24meV의 bandgap차를 갖는 양자우물을 영역을 동일한 기판상에 제작할 수 있음을 알 수 있다. 일반적으로 IFVD 방법으로 국부적으로 양자우물을 무질서화 하기 위해서는 SiNx/SiO2와 같은 강이한 박막을 사용하였지만 이 방법을 사용하는 경우 상이한 박막을 사용하는 데서 야기되는 제반 문제를 해결할 수 있을 것으로 판단된다. 따라서 이 기술은 기존의 광소자 제작을 위한 IFVD 방법의 문제점을 해결할 뿐만 아니라 결정 재성장 없이 도일한 기판상에 국부적으로 상이한 bandgap 영역을 만들 수 있기 때문에 광소자 제작에 적극 이용될 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.381-381
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• 2010

$(ZrO_2)_{0.66}(HfO_2)_{0.34}$ thin films as gate dielectrics have been proposed to overcome the problems of tunneling current and degradation mobility inachieving a thin equivalent oxide thickness. An extremely thin $SiO_2$ layer is used in order to separate the carrier in MOSFET channel from the dielectric field fluctuation caused by phonons in the dielectric which decreases the carrier mobility. The electronic and optical properties influenced the device performance to a great extent. $(ZrO_2)_{0.66}(HfO_2)_{0.34}$ dielectric films on p-Si (100) were grown by atomic layer deposition method, for which the conduction band offsets, valence band offsets and band gapswere obtained by using X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. The band gap, valence and conduction band offset values for $(ZrO_2)_{0.66}(HfO_2)_{0.34}$ dielectric thin film, grown on Si substrate were about 5.34, 2.35 and 1.87 eV respectively. This band alignment was similar to that of $ZrO_2$. In addition, The dielectric function (k, $\omega$), index of refraction n and the extinction coefficient k for the $(ZrO_2)_{0.66}(HfO_2)_{0.34}$ thin films were obtained from a quantitative analysis of REELS data by comparison to detailed dielectric response model calculations using the QUEELS-$\varepsilon$(k, $\omega$)-REELS software package. These optical properties are similar with $ZrO_2$ dielectric thin films.

• Advances in environmental research
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• v.4 no.2
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• pp.69-81
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• 2015

A new magnetite-silica core/shell nanocomposite ($Fe_3O4@nSiO_2@mSiO_2$) was synthesized and functionalized with trimethylchlorosilane (TMCS). The prepared nanocomposite was used for the removal of diesel oil from aqueous media. The characterization of magnetite-silica nanocomposite was studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), surface area measurement, and vibrating sample magnetization (VSM). Results have shown that the desired structure was obtained and surface modification was successfully carried out. FTIR analysis has confirmed the presence of TMCS on the surface of magnetite silica nanocomposites. The low- angle XRD pattern of nanocomposites indicated the mesoscopic structure of silica shell. Furthermore, TEM results have shown the core/shell structure with porous silica shell. Adsorption kinetic studies indicated that the nanocomposite was able to remove 80% of the oil contaminant during 2 h and fit well with the pseudo-second order model. Equilibrium studies at room temperature showed that the experimental data fitted well with Freundlich isotherm. The magnetic property of nanocomposite facilitated the separation of solid phase from aqueous solution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.20-20
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• 2010

The effect of excimer laser annealing on the structural and dielectric behaviors of $PbZr_{0.52}Ti_{0.48}O_3$ (PZT) thin films has been investigated. The amorphous PZT thin films were prepared on Pt/Ti/$SiO_2$/Si substrates by a sol-gel method. The PZT precursor was prepared from lead acetate, zirconium acetylacetonate, and titanium isopropoxide. The starting materials were dissolved in n-propanol and 1,3-propanediol. After, the amorphous PZT thin films were laser-annealed (using KrF excimer laser) as a function of the laser energy density and the number of laser pulse. Structural properties of PZT thin films are characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The dielectric characterization was done on a RT66A test system and a Agilent 4294A impedance analyzer. The PZT thin films show that excimer laser irradiation drastically improved the crystallization and dielectric properties of the PZT thin films, depending on the energy density and the pulse number.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.146-146
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• 2010

Electrical properties of Large-grain-size TIT with 7/7 ${\mu}m$ channel width and length which gate insulator is made of 20nm $SiO_2$ and 80nm $SiN_x$. was fabricated and measured with Large-grain-size technic(MICC) and compared to ELA technic's data. The field-effect mobility was decreased from 106.78 to $88.74\;cm^2$/Vs and threshold voltage also decreased from -1.8382 to -0.9529 V, when TFT process is changed from ELA technic to MICC technic. Subthreshold swing, also, increased from 0.22 to 0.32 V/dec and $I_{on/off}$ ratio decreased from $1.12{\times}10^8$ to $5.75{\times}10^7$.

• Journal of the Microelectronics and Packaging Society
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• v.1 no.2
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• pp.125-134
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• 1994

저항범위가 다른 두종류의 Ru계 후막저항계(1Kohm/sq. 100kohm/sq.)를 선택하여 도전상의 상전이 기구를 반응조건을 변화시켜 연구하였다. 저저항체의 경우 도전상으로는 RuO2였으며 700-100$0^{\circ}C$에서 1시간 반응한 경우 반응온도에 따른 구성상의 변화는 없었다 반응온도 90$0^{\circ}C$에서 반응시간이 경과함에 따라 도전상은 RuO2가 Glass의 구성성분인 Pb와 반응하여 Rb2(Ru1.69 Pb0.31)O6.5로 변하고 시간이 36시간 경과한 후에는 도전상이 Pb4Al2Si2O10인 결정으로 둘러 쌓이는 반응인 peritectic reaction이 일어났다. 고전항체의 경 우 도전상으로는 Pb2(Ru1.69 Pb0.31)O6.5로 변하고 시간이 36시간 경과한 후에는 더전상이 Pb4Al2Si2O10인 결정으로 둘러쌓이는 반응인 peritectic reaction 이 일어났다. 고저항체의 경 우 도전상으로는 Pb2(Ru1.69 Pb0.31)O6.5인 pyrochrole 상이였다. 100$0^{\circ}C$에서 1시간 반응시킬 경 우 도전상이 RuO2로 변하였다. 반응온도를 90$0^{\circ}C$로 하고 반응시간을 변화시키면 도전상인 Pb2(Ru1.69 Pb0.31)O6.5가 (Ru1.69Pb0.31)O4x로 변하면서 공존하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.93-96
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• 2002

In this study, PZT thin films were fabricated using sol-gel processing onto Si/$SiO_2$/Ti/Pt substrates. PZT sol with different Zr/Ti ratio(20/80, 30/70, 40/60, 52/48) were prepared, respectively. The films were fabricated by using the spin-coating method on substrates. The films were heat treated at $450^{\circ}C$, $650^{\circ}C$ by rapid thermal annealing(RTA). The preferred orientation of the PZT thin films were observed by X-ray diffraction(XRD), and Scanning electron microscopy(SEM). All of the resulting PZT thin films were crystallized with perovskite phase. The fine crystallinity of the films were fabricated. Also, we found that the ferroelectric properties from the dielectric constant of the PZT thin films were over 600 degrees, P-E hysteresis constant. And the leakage current densities of films were lower than $10^{-8}A/cm^2$. It is concluded that the PZT thin films by sol-gel process to be convinced of application for ferroelectric memory device.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.2006-2007
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• 2002

MEMS 공정을 이용하여 $SiN_x$를 지지층으로 한 $SiO_2$/Ta/PZT/Pt 의 박막 구조를 가지는 마이크로 켄틸레버를 제작하였다. 켄틸레버의 전기기계적 특성을 LDV (레이저 미소 변위 측정기)를 이용하여 측정하였으며, 이를 통해 전기기계적 거동을 분석하였다. 또한 무게 감지소자로서의 응용을 위해 Au의 증착을 통한 감도를 측정하였으며, streptavidin의 무게를 감지하기 위해 immobilization 공정을 거쳐 thiol 그룹 및 biotin을 표면에 고정화 시킨후 biotin-streptavidin 결합에 의한 전기기계적 신호 분석을 통해 생체 물질의 무게 감지 소자로의 응용을 평가하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.284-284
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• 2011

Recently, the increasing degree of device integration in the fabrication of Si semiconductor devices, etching processes of nano-scale materials and high aspect-ratio (HAR) structures become more important. Due to this reason, etch selectivity control during etching of HAR contact holes and trenches is very important. In this study, The etch selectivity and etch rate of TEOS oxide layer using ACL (amorphous carbon layer) mask are investigated various process parameters in CH2F2/C4F8/O2/Ar plasma during etching TEOS oxide layer using ArF/BARC/SiOx/ACL multilevel resist (MLR) structures. The deformation and etch characteristics of TEOS oxide layer using ACL hard mask was investigated in a dual-frequency superimposed capacitively coupled plasma (DFS-CCP) etcher by different fHF/ fLF combinations by varying the CH2F2/ C4F8 gas flow ratio plasmas. The etch characteristics were measured by on scanning electron microscopy (SEM) And X-ray photoelectron spectroscopy (XPS) analyses and Fourier transform infrared spectroscopy (FT-IR). A process window for very high selective etching of TEOS oxide using ACL mask could be determined by controlling the process parameters and in turn degree of polymerization. Mechanisms for high etch selectivity will discussed in detail.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.785-789
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• 2005

Low temperature deposition of silicon and silicon nitride films by catalytic CVD technique was studied for application to thin film transistors on plastic substrates for flexible AMOLEDs. The substrate temperature initially held at room temperature, and was controlled successfully below $150^{\circ}C$ during the entire deposition process. Amorphous silicon films having good adhesion, good surface morphology and sufficiently low content of atomic hydrogen were obtained and could be successfully crystallized using excimer laser without a prior dehydrogenation step. $SiN_x$ films showed a good refractive index, a high deposition rate, a moderate breakdown field and a dielectric constant. The Cat-CVD silicon and silicon nitride films can be good candidates for fabricating thin films transistors on plastic substrates to drive active-matrix organic light emitting display.