• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.61.2-61.2
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• 2015

In the past decades, green energy, such as solar energy, wind power, hydropower, biomass energy, geothermal energy, and so on, has been widely investigated and developed to solve energy shortage. Recently, organic solar cells have attracted much attention, because they have many advantages, including low-cost, flexibility, light weight, and easy fabrication [1-3]. Organic solar cells are as a potential candidate of the next generation solar cells. In this abstract, to improve the power conversion efficiency and the stability, the inverted polymer solar cells with various structures were developed [4-6]. The novel cell structures included the P3HT:PCBM inverted polymer solar cells with AZO nanorods array, with pentacene-doped active layer, and with extra P3HT interfacial layer and PCBM interfacial layer. These three difference structures could respectively improve the performance of the P3HT:PCBM inverted polymer solar cells. For the inverted polymer solar cells with AZO nanorods array as the electronic transportation layer, by using the nanorod structure, the improvement of carrier collection and carrier extraction capabilities could be expected due to an increase in contact area between the nanorod array and the active layer. For the inverted polymer solar cells with pentacene-doped active layer, the hole-electron mobility in the active layer could be balanced by doping pentacene contents. The active layer with the balanced hole-electron mobility could reduce the carrier recombination in the active layers to enhance the photocurrent of the resulting inverted polymer solar cells. For the inverted polymer solar cells with extra P3HT and PCBM interfacial layers, the extra PCBM and P3HT interfacial layers could respectively improve the electron transport and hole transport. The extra PCBM interfacial layer served another function was that led more P3HT moving to the top side of the absorption layer, which reduced the non-continuous pathways of P3HT. It indicated that the recombination centers could be further reduced in the absorption layer. The extra P3HT interfacial layer could let the hole be more easily transported to the MoO3 hole transport layer. The high performance of the novel P3HT:PCBM inverted polymer solar cells with various structures were obtained.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.40-45
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• 2004

This work presents a boundary estimation approach in electrical impedance imaging for binary-mixture fields based on a parallel structured multi-layer neural network. The interfacial boundaries are expressed with the truncated Fourier series and the unknown Fourier coefficients are estimated with the parallel structure of multi-layer neural network. Results from numerical experiments shows that the proposed approach is insensitive to the measurement noise and has a strong possibility in the visualization of binary mixtures for a real time monitoring.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.90-90
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• 2012

The electron/hole injections in organic electronic devices have long been an issue due to the large energy level mismatches between electrode and organic layer. To utilize the organic materials in electronic devices, functional thin layers have been used, which reduce the electron/hole injection barrier from electrode to organic material. Typically, inorganic compounds and organic molecules are used as an electron and hole injection layer, respectively. Recently, CsN3 and 1,4,5,8,- naphthalene-tetracarboxylic-dianhydride (NTCDA) are reported as a potential electron and hole injection layers. CsN3 shows unique properties that it breaks into Cs and N and thus Cs can dope organic layer into n-type. On the other side, hole injection anode, NTCDA forms gap states with anode material. In this presentation, we show the electronic structure changes upon the insertion of CsN3 and NTCDA at proper interfaces to reduce the charge injection barriers. These barrier reductions are correlated with device characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.311-314
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• 1999

Ferroelectric PZT heterolayered thin films were fabricated by spin coating method on the Pt/Ti/SiO$_2$/Si substrate using PZT(10/90) and PZT(90/10) metal alkoxide solutions. All PZT heterolayered films showed a homogeneous grain structure without presence of the rosette structure. It can be assumed that the lower PZT layers a role of nucleation site or seeding layer for the formation of the upper PZT layer. Zr and Ti diffusion into the Pt electrode were mainly distributed at the surface of Pt electrode beneath the PZT/Pt interface. The PZT/Pt interfacial layer showed a microstructure characterized by a grain phase surrounded by a Pb-deficient pyrochlore matrix phase. The relative dielectric constant and the dielectric loss of the PZT-6 film were 567 and 3.6, respectively.

• Journal of the Korean Ceramic Society
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• v.54 no.1
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• pp.66-69
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• 2017

In this study, the fabrication and electrical properties of aligned single-walled carbon nanotube (SWCNT) networks using a template-based fluidic assembly process are presented. This complementary metal-oxide-semiconductor (CMOS)-friendly process allows the formation of highly aligned lateral nanotube networks on $SiO_2/Si$ substrates, which can be easily integrated onto existing Si-based structures. To measure outstanding electrical properties of organized SWCNT devices, interfacial contact resistance between organized SWCNT devices and Ti/Au electrodes needs to be improved since conventional lithographic cleaning procedures are insufficient for the complete removal of lithographic residues in SWCNT network devices. Using optimized purification steps and controlled developing time, the interfacial contact resistance between SWCNTs and contact electrodes of Ti/Au is reached below 2% of the overall resistance in two-probe SWCNT platform. This structure can withstand current densities ${\sim}10^7A{\cdot}cm^{-2}$, equivalent to copper at similar dimensions. Also failure current density improves with decreasing network width.

• Journal of IKEEE
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• v.27 no.3
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• pp.220-224
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• 2023

Row hammering is a phenomenon in which bit flips occur in adjacent rows when accessing a particular row continuously, causing data damage, security problems, and poor computing performance. This paper analyzes the cause and response method of row hammering through TCAD simulation in 2ynm DRAM. In the experiment, the row hammering is reproduced while changing the parameters of the trap and the device structure, and the trap density, temperature. It analyzes the relationship with Active Wisdom, etc. As a result, it was confirmed that changes in trap parameters and device structures directly affect ΔV_cap/pulse. This enables a fundamental understanding of low hammering and finding countermeasures, and can contribute to improving the stability and security of DRAM.

• Transactions on Electrical and Electronic Materials
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• v.7 no.1
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• pp.16-20
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• 2006

In this paper, we investigated the effects of short-term oxygen plasma treatment of semiconducting silicone layer to improve interfacial performances in joints prepared with a insulating silicone materials. Surface characterizations were assessed using contact angle measurement and x-ray photoelectron spectroscopy (XPS), and then adhesion level and electrical performance were evaluated through T-peel tests and electrical breakdown voltage tests of treated semi-conductive and insulating joints. Plasma exposure mainly increased the polar component of surface energy from $0.21\;dyne/cm^2$ to $47\;dyne/cm^2$ with increasing plasma treatment time and then leveled off. Based on XPS analysis, the surface modification can be mainly ascribed to the creation of chemically active functional groups such as C-O, C=O and COH on semi-conductive silicone surface. This oxidized rubber layer is inorganic silica-like structure of Si bound with three to four oxygen atoms ($SiO_x,\;x=3{\sim}4$). The oxygen plasma treatment produces an increase in joint strength that is maximum for 10 min treatment. However, due to brittle property of this oxidized layer, the highly oxidized layer from too much extended treatment could be act as a weak point, decreasing the adhesion strength. In addition, electrical breakdown level of joints with adequate plasma treatment was increased by about $10\;\%$ with model samples of joints prepared with a semi-conducting/ insulating silicone polymer after applied to interface.

• Korean Journal of Materials Research
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• v.19 no.11
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• pp.625-630
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• 2009

Embedding of active devices in a printed circuit board has increasingly been adopted as a future electronic technology due to its promotion of high density, high speed and high performance. One responsible technology is to embedded active device into a dielectric substrate with a build-up process, for example a chipin-substrate (CiS) structure. In this study, desmear treatment was performed before Cu metallization on an FR-4 surface in order to improve interfacial adhesion between electroless-plated Cu and FR-4 substrate in Cu via structures in CiS systems. Surface analyses using atomic force microscopy and x-ray photoemission spectroscopy were systematically performed to understand the fundamental adhesion mechanism; results were correlated with peel strength measured by a 90o peel test. Interfacial bonding mechanism between electrolessplated Cu and FR-4 substrate seems to be dominated by a chemical bonding effect resulting from the selective activation of chemical bonding between carbon and oxygen through a rearrangement of C-C bonding rather than from a mechanical interlocking effect. In fact, desmear wet treatment could result in extensive degradation of FR-4 cohesive strength when compared to dry surface-treated Cu/FR-4 structures.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.133-138
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• 2017

We investigated the interface defect engineering and reaction mechanism of reduced transition layer and nitride layer in the active plasma process on 4H-SiC by the plasma reaction with the rapid processing time at the room temperature. Through the combination of experiment and theoretical studies, we clearly observed that advanced active plasma process on 4H-SiC of oxidation and nitridation have improved electrical properties by the stable bond structure and decrease of the interfacial defects. In the plasma oxidation system, we showed that plasma oxide on SiC has enhanced electrical characteristics than the thermally oxidation and suppressed generation of the interface trap density. The decrease of the defect states in transition layer and stress induced leakage current (SILC) clearly showed that plasma process enhances quality of $SiO_2$ by the reduction of transition layer due to the controlled interstitial C atoms. And in another processes, the Plasma Nitridation (PN) system, we investigated the modification in bond structure in the nitride SiC surface by the rapid PN process. We observed that converted N reacted through spontaneous incorporation the SiC sub-surface, resulting in N atoms converted to C-site by the low bond energy. In particular, electrical properties exhibited that the generated trap states was suppressed with the nitrided layer. The results of active plasma oxidation and nitridation system suggest plasma processes on SiC of rapid and low temperature process, compare with the traditional gas annealing process with high temperature and long process time.

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.478-486
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• 1995

Cu/NbTi multilayer thin films and superconducting wires were fabricated and heat treated with conventional annealing and analyzed by differential scanning calorimetry (DSC) as a basic study for the enhancement of Jc. Interfacial reactions of Cu/NbTi multilayer thin films and superconducting wires were investigated with optical microscope, SEM, and XRD. According to the effective heat of formation (EHF) model, CU$\_$3/Ti was predicted as a first phase. However, considering the crystalline structure and thermodynamics, CuTi was predicted as a first phase. According to the results of DSC and XRD, CU$\_$2/Ti was found to be the first phase, followed by the formation Of CU$\_$4/Ti. The difference in first crystalline phase between the experimental result and the predicted one was discussed. In case of Cu/NbTi superconducting wires, the compounds formed at the Cu/NbTi interface grew with annealing time and the amount of compounds formed in Nb-47wt%Ti alloy was larger than that in Nb-50wt%Ti alloy. It seemed that the incubation time for the formation of compounds in Nb-50wt%Ti alloy was longer than that formed in Nb-47wt%Ti alloy. Also, the diffusion was the rate controlling step for the growth of compounds in all specimens. These compounds were formed at 500-600.deg. C for I hour annealing and, thus, the drawing time below I hour must be required to minimize the growth of compounds for the enhancement of Jc.