• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.85-85
• /
• 2010

Graphene, the building block of graphite, is one of the most promising materials due to their fascinating electronic transport properties. The pseudo-two-dimensional sp2 bonding in graphene layers yields one of the most effective solid lubricants. In this poster, we present the correlation between electrical and nanomechanical properties of graphene layer grown on Cu/Ni substrate with CVD (Chemical Vapor Deposition) method. The electrical (current and conductance) and nanomechanical (adhesion and friction) properties have been investigated by the combined apparatus of friction force microscopy/conductive probe atomic force microscopy (AFM). The experiment was carried out in a RHK AFM operating in ultrahigh vacuum using cantilevers with a conductive TiN coating. The current was measured as a function of the applied load between the AFM tip and the graphene layer. The contact area has been obtained with the continuum mechanical models. We will discuss the influence of mechanical deformation on the electrical transport mechanism on graphene layers.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.1
• /
• pp.8-12
• /
• 2005

Indium tin oxide(ITO) surface treated by Oxygen plasma has been in situ analyzed using XPS(X-ray Photoelectron Spectroscopy) and EDS(Energy Dispersive Spectroscopy), to investigate the relations between the properties of the ITO surface and the properties of OLED(Organic Light Emitting Diode). We measured electrical resistivity using Four-Point-Probe and calculated sheet resistance, and ITO surface roughness was measured by AFM(Atomic Force Microscope). We fabricated OLED using substrate that was treated optimum ITO surface. The plasma treatment of the ITO surface lowered the operating voltage of the OLED. We have obtained an improvement of luminance and decrease of turn-on voltage.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.57-58
• /
• 2002

Asperity arrays and Independent asperities were fabricated on a silicon plate. Then pull-off and friction forces were measured on each asperity pattern by using AFM (atomic force microscope) in humid air and high vacuum of $2{\times}10^{-5}$ Pa. The probe of AFM cantilever has a flat square of about $1\;{\mu}m^2$ on its tip. The results showed that the pull-off force was proportional to the curvature radius of asperity peak in each ambient condition. The friction force was proportional to the pull-off force and was slightly higher in the humid air than in the high vacuum.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.274-274
• /
• 2006

Recently, conjugated polymer solar cells have attracted a great deal of attention. In this work, we applied the various scanning probe techniques to characterize composite materials typically used to fabricate polymer solar cells: poly-3(hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and P3HT/PCBM/Au nanoparticle (NP) samples. The latter is studied due to the idea of using the gold NP surface plasmon to enhance the optical absorption of the composite films. AFM is used to characterize the film morphology whereas conducting AFM is used to study the charge transport properties at the nanoscale. We found that there is a direct correlation between the nanoscale charge transport measurements and the device efficiencies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.522-525
• /
• 2004

ITO thin films $({\sim}150\;nm)$ are deposited on glass substrates by different deposition condition. The sheet resistance of ITO thin films measured by using a four probe station. The microstructure of these films is determined using a X-ray diffractometer (XRD) and a scanning electron microscope (SEM) and a atomic force microscope (AFM). The sheet resistance of ITO thin films compared $s_{11}$ values by using a near field scanning microwave microscope.

• Transactions of the Society of Information Storage Systems
• /
• v.3 no.2
• /
• pp.59-65
• /
• 2007

Scanning Prove Microscope (SPM) - based Data Storage (SDS)는 Atomic Force Microscope (AFM)을 이용하여 Cantilever Tip 이 저장 장치 미디어에 나노미터 단위로 비트를 읽고, 쓰고 지우는 저장 장치로써, x, y 두 축을 이용한다. 따라서 축간 coupling 의 영향이 크게 발생한다. 따라서 축간 coupling 의 영향을 고려하여 제어기를 설계하여야 한다. 본 논문은 coupling 요소를 제거하기 위하여 Feedforward Decoupler 를 설계하여 Stage 의 입력 앞 단에 추가하는 방법을 제안하였다. Feedforward Decoupler 를 추가함으로써 coupling 요소가 줄어드는 것을 모의 실험을 통해 확인한다. 이를 통해 나노급으로 보다 정밀한 제어가 가능함을 확인하였다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.430-430
• /
• 2011

Graphene, one single atomic layer of graphite, has attracted extensive attention in various research fields since its first isolation from graphite. Application in the future electronics requires better understanding and manipulation of electronic properties of graphene supported on various solid substrates. Here, we present a study on charge doping and morphology of graphene prepared on atomically flat and highly polar mica substrates. Ultra-flat single-layer graphene was prepared by micro-exfoliation of graphite followed by deposition on cleaved mica substrates. Atomic force microscopy (AFM) revealed presence of ultra-thin water films formed in a layer-by-layer manner between graphene and mica substrates. Raman spectroscopy showed that a few angstrom-thick water films efficiently block electron transfer from graphene to mica. Hole doping in graphene caused by underlying mica substrates was also visualized by scanning Kelvin probe microscopy (SKPM).

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.461-462
• /
• 2006

This paper reports on the development of a scanning probe microscopy(SPM) tip with caborn nanotubes. We used an electric field which causes dielectrophoresis(DEP), to align and deposit CNTs on a metal-coated SPM tip. Using the CNT attached SPM tip, we have obtained an enhanced resolution and wear property compared to that from the bare silicon tip through the scanning of the surface of the bio materials. The carbon nanotube tip align toward the source of the ion beam allowing their orientation to be changed at precise angles. By this technique, metal coated carbon nanotube tips that are several micrometer in length are prepared for scanning probe microscopy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.111-111
• /
• 2011

Arrangement of individual atoms and molecules with atomic precision and understanding the resulting properties at the molecular level are ultimate goals of chemistry, biology, and materials science. For the past three decades, scanning probe microscopy has made strides towards these goals through the direct observation of individual atoms and molecules, enabling the discovery of new and unexpected phenomena. This talk will discuss the origin of forces governing motion of small organic molecules and their extended self-assembly into two-dimensional surface structures by direct observation of individual molecules using scanning tunneling microscopy (STM). In addition, atomic force microscopy (AFM) is utilized for the investigation of fundamental mechanisms of bone mineral dissolution by examining atomically well characterized simulated bone minerals under aqueous solution environments.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.581-584
• /
• 1998

TiN thin films were grown on (100) Si substrate by atomic layer epitaxy at 130 - $240^{\circ}C$ using TEMAT and NH3 as precursors. Reactants were injected into the reactor in sequence of TEMAT precursor vapor pulse, N2 purging gas pulse, NH3 gas pulse and N2 purging gas pulse so that gas-phase reactions could be removed. The films were characterized by means of x-ray diffraction(XRD), 4-point probe, atomic force microscopy(AFM) and auger electron spectroscopy(AES).