• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.659-659
• /
• 2013

Recently, graphene has been intensively studied due to the fascinating physical, chemical and electrical properties. It shows high carrier mobility, high current density, and high thermal conductivity compare with conventional semiconductor materials even it has single atomic thickness. Especially, since graphene has fantastic electrical properties many researchers are believed that graphene will be replacing Si based technology. In order to realize it, we need to prepare the large and uniform graphene. Chemical vapor deposition (CVD) method is the most promising technique for synthesizing large and uniform graphene. Unfortunately, CVD method requires transfer process from metal catalyst. In transfer process, supporting polymer film (Such as poly (methyl methacrylate)) is widely used for protecting graphene. After transfer process, polymer layer is removed by organic solvents. However, it is impossible to remove it completely. These organic residues on graphene surface induce quality degradation of graphene since it disturbs movement of electrons. Thus, in order to get an intrinsic property of graphene completely remove of the organic residues is the most important. Here, we introduce modified wet graphene transfer method without PMMA. First of all, we grow the graphene from Cu foil using CVD method. And then, we deposited several metal films on graphene for transfer layer instead of PMMA. Finally, we fabricate graphene FET devices. Our approaches show low defect density and non-organic residues in comparison with PMMA coated graphene through Raman spectroscopy, SEM and AFM. In addition, clean graphene FET shows intrinsic electrical characteristic and high carrier mobility.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.458-458
• /
• 2013

We investigated a study on the thermal degradation of boron doped zinc-oxide (BZO) layer which used as a transparent conducting layer on the Cu (In1-xGax) Se2 (CIGS) based thin film solar cells. Devices were annealed under the temperature of $100^{\circ}C$ or 100 hours and then Hall measurement was carried out to characterize the parameters of mobility (${\mu}Hall$), resistivity (${\rho}$), conductivity (${\sigma}$) and sheet resistance (Rsh). The initial values of ${\mu}Hall$, ${\rho}$, ${\sigma}$ and Rsh were $29.3cm^2$/$V{\cdot}s$, $2.1{\times}10^{-3}{\Omega}{\cdot}cm$, $476.4{\Omega}^{-1}{\cdot}cm^{-1}$ and $19.1{\Omega}$/${\Box}$ respectively. After the annealing process, the values were $4.5cm^2$/$V{\cdot}s$, $12.8{\times}10^{-3}{\Omega}{\cdot}cm$, $77.9{\Omega}^{-1}{\cdot}cm^{-1}$ and $116.6{\Omega}$/${\Box}$ respectively. We observed that ${\mu}Hall$ and ${\sigma}$ were decreased, and ${\rho}$ and Rsh were increased. In this study, BZO layer plays an important role of conducting path for electrons generated by incident light onthe CIGS absorption layer. Therefore, the degradation of BZO layer characterized by the parameters of ${\mu}Hall$, ${\rho}$, ${\sigma}$ and Rsh, affect to the cell efficiency.

• 한국표면공학회지
• /
• 제35권1호
• /
• pp.33-38
• /
• 2002

CrN 박막이 펄스마그네트론증착법에 의하여 glass, Si(110), AISI 1040 steel 위에 증착되어졌다. 각 기판 위에 증착된 CrN 박막의 구조는 표면의 접촉특성 보다는 표면의 구조에 영향을 받는 것으로 판단되어 진다. 또한 grain의 크기는 기판에 관계없이 증착 시간이 증가함에 따라 증가한다. AISI 1040 steel 위에 증착된 CrN 박막의 grain 성장과 구조는 glass와 Si에 비하여 바이어스에 강하게 영향을 받는다. 이러한 결과는 glass 와 Si 보다도 금속이 높은 전기전도성을 가지고 있기 때문인 것으로 생각되어 진다.

• Composites Research
• /
• 제25권3호
• /
• pp.70-75
• /
• 2012

음향작동기의 응용으로, CNT, ITO와 xGnP로 코팅된 PVDF 나노복합재료의 계면접착 내구성과 전기적 특성을 평가하였다. CNT, ITO와 xGnP의 고유 전기적 특성으로 인하여 xGnP로 코팅된 나노복합재료가 CNT, ITO 경우보다 다소 낮은 전기저항을 나타내었으나, 모두 양호한 음향특성을 보여주었다. 나노복합재료의 계면 내구성은 정적 접촉각 시험을 통해 미처리 CNT 와 플라즈마 처리된 CNT 그리고 플라즈마 처리된 PVDF간의 표면에너지, 접착일, 그리고 퍼짐계수를 평가하여 계면 내구성과의 상호 관련성을 확인하였다. 음향 작동기로서 xGnP 나노복합재료의 최적의 작동성은 시편의 곡률반경, 코팅정도를 달리 하여 음향 측정기를 사용하여 음향특성을 측정하였다. 나노재료의 고유의 전기적 특성으로 인하여 xGnP가 CNT나 ITO보다 음향작동기로서 더 적합함을 알 수 있었다. 곡률반경이 약 15도일 때 가장 적합하며, 코팅두께에 따라 음향특성이 차이가 나지만 투명도도 좋으면서 음향특성도 우수한 음향 작동기를 제작할 수 있었다.

• 한국환경과학회지
• /
• 제14권8호
• /
• pp.801-810
• /
• 2005

The phosphor and ITO(Indium Tin Oxide) films for video phone tube (VPT) were simply prepared by the screen printing and thermal transfer methods. The increasing order of thermal firing of acrylic binder for phosphor and ITO was M6003 < M6664 < A/A 1919 < M500l < M670 1 and all mass of binders were perfectly decomposed at lower temperature than $400^{\circ}C.$ After thermal firing of phosphor paste, the residual of binder on the surface of phosphor could not be found by SEM. Aerosil as thickner provides the thixotropy property for phosphor paste but decrease the brightness of phosphor screen as residual after thermal firing. Since the thixotropy of M5001 binder without aerosil was shown and the storage modulus of phosphor paste by increasing the angular frequency was not nearly changed and the decrease of the storage modulus of phosphor paste by increasing the strain was remarkably shown. It was possible to prepare the phosphor paste which was predominant in the plate separation and the reproduction of pattern after the screen printing. Since the addition of dispersing agent to improve the printing process decreases the electrical conductivity and light transmission of ITa film, it could be found to be necessary the development of binder for phosphor paste that decreases the amount of dispersing agent possibly and does not use the aerosil as additive.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.168-168
• /
• 2008

Dimension of a transistor has rapidly shrunk to increase the speed of device and to reduce the power consumption. However, it is accompanied with several problems like direct tunneling through the gate dioxide layer and low conductivity characteristic of poly-Si gate in nano-region. To cover these faults, study of new materials is urgently needed. Recently, high dielectric materials like $Al_2O_3$, $ZrO_2$, and $HfO_2$ are being studied for equivalent oxide thickness (EOT). However, poly-Si gate is not compatible with high-k materials for gate-insulator. Poly Si gate with high-k material has some problems such as gate depletion and dopant penetration problems. Therefore, new gate structure or materials that are compatible with high-k materials are also needed. TiN for metal/high-k gate stack is conductive enough to allow a good electrical connection and compatible with high-k materials. According to this trend, the study on dry etching of TiN for metal/high-k gate stack is needed. In this study, the investigations of the TiN etching characteristics were carried out using the inductively coupled $BCl_3$-based plasma system and adding $Cl_2$ gas. Dry etching of the TiN was studied by varying the etching parameters including $BCl_3$/Ar gas mixing ratio, RF power, DC-bias voltage to substrate, and $Cl_2$ gas addition. The plasmas were characterized by optical emission spectroscopy analysis. Scanning electron microscopy was used to investigate the etching profile.

• 전기학회논문지P
• /
• 제57권2호
• /
• pp.140-145
• /
• 2008

The purpose of this paper is to discuss the fabrication of $\beta$-PVDF($\beta$-Polyvinylidene fluoride, ${\beta}-PVF_2$) organic thin films using the vapor deposition method. Vapor deposition was performed under the following conditions: the temperature of evaporator, the applied electric field, and the pressure of reaction chamber were $270^{\circ}C$, 142.4 kV/cm, and $2.0{\times}10^{-5}\;Torr$, respectively. The molecular structure of the evaporated organic thin films were evaluated by a FT-IR. The results showed that the characteristic absorption peaks of $\beta$-form crystal increase from 72% to 95.5% with an increase in the substrate temperature. In the analysis of the electric characteristics, the abnormal increases in the relative dielectric constant and the dielectric loss factor in the regions of low frequency and high temperature are known to be caused by inclusion of impurity carriers in the PVDF organic thin films. In order to analyze quantitatively the abnormalities in the conductivity mechanism caused by ionic impurities, the product of the ion density and the mobility that affect the electrical property in polymeric insulators is analyzed. In the case of a specimen produced by varying the substrate temperature from $30^{\circ}C$ to $105^{\circ}C$, the product of mobility and the ion density decreased from $4.626{\times}10^8$ to $8.47{\times}10^7/V{\cdot}cm{\cdot}s$. This result suggests that the higher the substrate temperature is maintained, the better excluded the impurities are, and the more electrically stable material can be obtained.

• Korean Chemical Engineering Research
• /
• 제49권6호
• /
• pp.781-785
• /
• 2011

본 연구에서는 나노 크기의 세리아를 사마리움으로 일부 도핑(samaria-doped ceria(SDC))한 분말을 urea를 첨가제로 사용하여 수열합성법으로 합성하였으며 그 특성들을 XRD, FESEM, TEM 등을 통해 관찰하였다. 합성 시간 및 합성온도가 증가함에 따라 분말의 결정성 및 입도가 증가함을 확인하였다. 또한 이온전도도의 측정을 통해 합성된 SDC 파우더가 중 저온(600~$800^{\circ}C$) 부근에서 0.1 S/cm의 이온전도도를 보여 중 저온형 고체산화물 연료전지(IT-SOFC)의 고체 전해질에 적합함을 확인할 수 있었다. 합성된 SDC 분말은 중·저온 고체산화물 연료전지의 음극지지형 전해질로 사용하기 위해 전기영동 증착 방법을 이용하여 다공성 NiO-SDC 기판 위에 SDC 박막 증착을 시도하였다. 증착 용액은 acetone을 용매로 사용하고, 20V의 인가전압으로 10초간 증착한 결과 얇고 치밀하며 기공이 없는 SDC 박막이 형성되었음을 FESEM 분석을 통해 확인할 수 있었다.

• 대한기계학회논문집B
• /
• 제35권11호
• /
• pp.1133-1137
• /
• 2011

마이크로 수준에서의 온도측정을 위하여 유리 피펫 기반의 프로브형 온도센서를 제작하였다. 이를 이용하여 정밀도 ${\pm}$ 0.1 K 를 가지는 온도측정 보정 실험을 수행하였다. 본 연구에서 제작한 방식은 저온의 용융점을 갖는 솔더합금(Sn)을 피펫에 내부에 주입하고 외부에 니켈(Ni) 코팅을 하여 열전대를제작함으로써 저비용의 프로브형 온도센서를 구현하였다. 제작된 센서 팁 끝단의 지름은 5 Am 에서 30 Am 로 피펫을 가열하여 당기는 방식으로 프로브 끝단의 크기를 조절하였다. 제작된 온도센서는 챔버내에서 정밀하게 제어된 온도 조절기를 사용하여 보정하였으며, 이를 통하여 얻어진 열전계수의 범위는 8.46 에서 $8.86{\mu}V$/K 의 값을 얻었다. 이를 이용하면 MEMS 소자, 세포, 티슈 등의 바이오 소재의 온도 및 열특성 측정용 프로브로 활용할 수 있을 것으로 생각된다.

• Elastomers and Composites
• /
• 제47권4호
• /
• pp.292-296
• /
• 2012

폴리비닐알콜, 규소텅스텐산, 인산 및 수용액으로 구성된 $80{\mu}m$의 두께의 고분자겔 전해질 필름을 제조하여 활성탄소계 전기이중층 케페시터를 제조하였다. 제조한 고분자겔 전해질 필름은 상온에서 $10^{-2}S\;cm^{-1}$의 높은 이온전도도를 나타내었으며, 본 전해질 필름을 적용한 활성탄소계 전기이중층 케패시터는 100 mV/s에서 $58F\;g^{-1}$의 높은 캐패시턴스 특성과 우수한 수명특성을 나타내었다.