• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.658-658
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• 2013

Graphene is an attractive material for various device applications due to great electrical properties and chemical properties. However, lack of band gap is significant hurdle of graphene for future electrical device applications. In the past few years, several methods have been attempted to open and tune a band gap of graphene. For example, researchers try to fabricate graphene nanoribbon (GNR) using various templates or unzip the carbon nanotubes itself. However, these methods generate small driving currents or transconductances because of the large amount of scattering source at edge of GNRs. At 2009, Bai et al. introduced graphene nanomesh (GNM) structures which can open the band gap of large area graphene at room temperature with high current. However, this method is complex and only small area is possible. For practical applications, it needs more simple and large scale process. Herein, we introduce a photosensitive graphene device fabrication using CdSe QD coated nano-porous graphene (NPG). In our experiment, NPG was fabricated by thin film anodic aluminum oxide (AAO) film as an etching mask. First of all, we transfer the AAO on the graphene. And then, we etch the graphene using O2 reactive ion etching (RIE). Finally, we fabricate graphene device thorough photolithography process. We can control the length of NPG neckwidth from AAO pore widening time and RIE etching time. And we can increase size of NPG as large as 2 $cm^2$. Thin CdSe QD layer was deposited by spin coatingprocess. We carried out NPG structure by using field emission scanning electron microscopy (FE-SEM). And device measurements were done by Keithley 4200 SCS with 532 nm laser beam (5 mW) irradiation.

• 한국재료학회지
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• 제29권8호
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• pp.491-496
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• 2019

In this study, we prepare pure $WO_3$ inverse opal(IO) film with a thickness of approximately $3{\mu}m$ by electrodeposition, and an ultra-thin $TiO_2$ layer having a thickness of 2 nm is deposited on $WO_3$ IO film by atomic layer deposition. Both sets of photoelectrochemical properties are evaluated after developing dye-sensitized solar cells(DSSCs). In addition, morphological, crystalline and optical properties of the developed films are evaluated through field-emission scanning electron microscopy(FE-SEM), High-resolution transmission electron microscopy(HR-TEM), X-ray diffraction(XRD) and UV/visible/infrared spectrophotometry. In particular, pure $WO_3$ IO based DSSCs show low $V_{OC}$, $J_{SC}$ and fill factor of 0.25 V, $0.89mA/cm^2$ and 18.9 %, achieving an efficiency of 0.04 %, whereas the $TiO_2/WO_3$ IO based DSSCs exhibit $V_{OC}$, $J_{SC}$ and fill factor of 0.57 V, $1.18mA/cm^2$ and 50.1 %, revealing an overall conversion efficiency of 0.34 %, probably attributable to the high dye adsorption and suppressed charge recombination reaction.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.420-423
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• 2003

[ $TiO_2$ ] thin films were fabricated by DC magnetron sputtering system at by controlling deposition times, ratios of $Ar:O_2$ partial presser ratio and substrate conditions. And the surface, cross-section morphology, microstructure, and composition ratio of the films were analyzed by FE-SEM, TEM and XPS. Besides, the optical absorption and transmittance of the $TiO_2$ films were measured by a UV-VIS-NIR Spectrophotometer, and photocatalytic properties were studied by G C Analyzer & Data Analysis system. As the result, when $TiO_2$ thin film was made at deposition time of 120[min] and $Ar:O_2$ ratio of 60:40, the best structural and optical properties among many thin films could be accepted. The best results of properties were as follows: thickness; $360{\sim}370[nm]$, grain size; 40[m], gap between two peak binding energy, $5.8{\pm}0.05[eV]$ ($2p_{3/2}$ peak and $2p_{1/2}$ peak of Ti was show at $458.3{\pm}0.05[eV]$ and $464.1{\pm}0.05[eV]$ respectively), binding energy; $530{\pm}0.05\;[eV]$, opticalenergy band gap; 3.4[eV].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.168-171
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• 2003

Bismuth layered structure, Cerium-substituted $Bi_4Ti_3O_{12}$ ($(Bi,Ce)_4Ti_3O_{12}$) thin films were prepared on the $Pt/TiO_2/SiO_2/Si$ substrates by the pulsed laser deposition method. We investigated the Ce-subsitituted effect on the grain orientation and ferroelectric properties. $Ce^{3+}$ ion substitution for $Bi^{3+}$ ion in perovskite layers of BTO decreased the deeree of c-axis orientation and increased the remanent polariation (2Pr). The structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The $(Bi,Ce)_4Ti_3O_{12}$ (BCT) thin films, which were annealed $700^{\circ}C\;and\;800^{\circ}C$ for 10min and 30min, showed a perovskite phase and dense microstructure. As the thickness of the BCT film was decresed that the ferroelectric properties of the BCT thin films were good.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.154-157
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• 2003

$TiO_2$ thin films were fabricated by RF magnetron sputtering system at by controlling deposition times, ratios of $Ar:O_2$ partial presser ratio and substrate conditions. And the surface, cross-section morphology, microstructure, and composition ratio of the films were analyzed by FE-SEM, TEM and XPS. Besides, the optical absorption and transmittance of the $TiO_2$ films were measured by a UV-VIS-NIR Spectrophotometer, and photocatalytic properties were studied by G${\cdot}$C Analyzer & Data Analysis system. As the result, when $TiO_2$ thin film was made at deposition time of 120[min] and $Ar:O_2$ ratio of 60:40, the best structural and optical properties among many thin films could be accepted. The best results of properties were as follows: thickness; 360~370[nm), grain size; 40[nm], gap between two peak binding energy; $5.8{\pm}0.05[eV]$ ($2_{p3/2}$ peak and $2_{p1/2}$ peak of Ti was show at $458.3{\pm}0.05[eV]$ and $464.1{\pm}0.05[eV]$ respectively), binding energy; $530{\pm}0.05[eV]$, optical energy band gap; 3.4[eV].

• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.631-635
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• 2006

The properties of metal interlayered DLC films between the Si substrate and the DLC films were studied. DC magnetron sputtering method has been used to deposit intermediate layers of metals. And RF-PECVD method has been employed to synthesize DLC onto substrates of the silicon and metal layers. After we used metal Inter-layers, such as chromium, nickel, titanium and we studied tribological properties of the DLC films. The thickness of films were observed by field emission scanning electron microscope (FE-SEM). Also the surface morphology of the films were observed by an atomic force microscope (AFM). The crystallographic properties of the films were analyzed with X-ray diffraction (XRD), the friction coefficients were investigated by AFM in friction force microscope (FFM) mode. Tribological performances of the films were estimated by nano-indenter, stress tester measurement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.139-140
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• 2006

PZT박막은 비휘발성 재료로 유전율이 높고 항전력이 작으면서 잔류 분극랑이 크기 때문에 적합한 특성을 가지고 FeRAM에 매력적인 물질이다. CMP(chemical mechanical polishing)는 기존의 회생막의 전면 식각 공정과는 달리 특정 부위의 제거 속도를 조절함으로써 평탄화 하는 기술로 wafer 전면을 회전하는 탄성 패드 사이에 액상의 Slurry를 투입하여 연마하는 기술이다. 본 논문에서는 CMP 공정으로 제조한 PZT박막 캐패시터에서 CMP 후처리공정(세척)의 유무 및 종류에 따라 피로특성에 대하여 연구하였다, PZT 박막의 캐패시터의 피로 특성을 연구한 결과 CMP 후처리공정 SC-l용액을 사용하여 세정공정을 하였을때 가장 향상된 PZT 캐패시터의 피로특성이 나타났다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2009년도 정기총회 및 동계학술연구발표회
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• pp.201-202
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• 2009

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.677-680
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• 2012

The dependency of annealing temperature on the electrical performances in amorphous silicon-zinc-tin-oxide thin film transistors (SZTO-TFT) has been investigated. The SZTO channel layers were prepared by using radio frequency (RF) magnetron sputtering method with different annealing treatment. The field effect mobility (${\mu}_{FE}$) increased and threshold voltage ($V_{th}$) shifted to negative direction with increasing annealing temperature. As a result, oxygen vacancies generated in SZTO channel layer with increasing annealing temperature resulted in negative shift in $V_{th}$ and increase in on-current.

• 대한기계학회논문집A
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• 제29권4호
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• pp.526-533
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• 2005

Reliability problem in inkjet printhead, one of MEMS devices, is also very important. To eject an ink drop, the temperature of heater must be high so that ink contacting with surface reaches above $280^{o}C$ on the instant. Its heater is embedded in the thin multi-layer in which several materials are deposited. MEMS processes are the main sources of residual stresses development. Residual stress is one of the factors reducing the reliability of MEMS devices. We measured residual stresses of single layers that consist of multilayer. FE analysis is performed using design of experiment(DOE). Transient analysis for heat transfer is performed to get a temperature distribution. And then static analysis is performed with the temperature distribution obtained by heat transfer analysis and the measured residual stresses to get a stress distribution in the structure. Although the residual stress is bigger than thermal stress, thermal stress is more influential on fatigue life.