• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1247-1249
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• 1993

In this paper, NUDFET(NonUniformly Doped Field Effect Transistor) is presented as an alternative which offers the possibility of reducing the power necessary to operate switching circuits without a substantial loss in speed. The purpose of this NUDFET is to modify the electric field profile in order to cause carrier velocity saturation to occur at a lower voltage than it would occur in the uniformly doped device of the same channel length. The more MESFET and NUDFET circuits are realized, the more accurate model ins the performance of these devices become required. Analytic model ins was replaced by numerical analysis because of the complexity of device configuration. In this paper, FEM is selected because of simpler local mesh refinement and smaller computer memory than FDM. For accurate analysis, this paper has applied the Scharfetter-Gummel(S-G) Scheme and seven-point Gaussian Quadrature rule to assembly of the finite-element stiffness matrices and right-hand side vector of the semiconductor equations.

• 공업화학
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• 제34권1호
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• pp.94-97
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• 2023

BTPSF와 BDTSF는 유기발광다이오드용 스파이로플루오렌 모이어티를 기반으로 하는 새로운 청색 발광 물질로 성공적으로 합성되었다. BTPSF와 BDTSF는 촉매를 사용하지 않고 Diels-Alder 반응을 통해 합성하여 고순도를 얻었다. 합성된 물질의 광발광 스펙트럼은 용액 상태에서 약 381, 407 nm, 필름 상태에서 각각 395, 434 nm의 최대 발광 파장을 나타내어 자외선과 짙은 청색 발광색을 나타냈다. 합성된 BDTSF 물질은 non-doped 소자의 EML로 적용되었으며, 전류 효율은 0.61 cd/A이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.647-647
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• 2013

We apply a density functional theory (DFT) and DFT-based non-equilibrium Green's function approach to study the structures, energetics and charge transport characteristics of nitrogen-doped graphene and graphene nanoribbons (GNRs) with additional doping of phosphorus or boron atoms. Considering graphitic, pyridinic, and porphrin-like N doping sites and increasing N-doping concentration, we analyze the structures of N-P and N-B doped graphene and particularly focus on how they affect the charge transport along the lateral direction. For the GNRs, we also consider the differences between defects formed at the edge and bulk regions. Implications of our findings in the context of electronic and energy device applications will be also discussed.

• 한국전기전자재료학회논문지
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• 제20권12호
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• pp.1017-1021
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• 2007

To implement tera bit level non-volatile memories of low power and fast operation, proving statistical reproductivity and satisfying reliabilities at the nano-scale are a key challenge. We fabricate the charge trapping nano scaled SONOS unit memories and 64 bit flash arrays and evaluate reliability and performance of them. In case of the dielectric stack thickness of 4.5 /9.3 /6.5 nm with the channel width and length of 34 nm and 31nm respectively, the device has about 3.5 V threshold voltage shift with write voltage of $10\;{\mu}s$, 15 V and erase voltage of 10 ms, -15 V. And retention and endurance characteristics are above 10 years and $10^5$ cycle, respectively. The device with LDD(Lightly Doped Drain) process shows reduction of short channel effect and GIDL(Gate Induced Drain Leakage) current. Moreover we investigate three different types of flash memory arrays.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.343-344
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• 2012

It has been known since the mid 1960s that Ag can be photodissolved in chalcogenide glasses to form materials with interesting technological properties. In the 40 years since, this effect has been used in diverse applications such as the fabrication of relief images in optical elements, micro photolithographic schemes, and for direct imaging by photoinduced Ag surface deposition. ReRAM, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of a conductive filament in a solid electrolyte. Especially, Ag-doped chalcogenide glasses and thin films have become attractive materials for fundamental research of their structure, properties, and preparation. Ag-doped chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in ReRAM devices. In this paper, we investigated the nature of thin films formed by the photo-dissolution of Ag into Ge-Se glasses for use in ReRAM devices. These devices rely on ion transport in the film so produced to create electrically programmable resistance states. [1-3] We have demonstrated functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of Ag+ ions photo-induced diffusion in thin chalcogenide films is considered. The influence of Ag+ ions is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Saturated Ag+ ions have been used in the formation of conductive filaments at the solid electrolyte which is the active medium in ReRAM devices. Following fabrication, the cell displays a metal-insulator-metal structure. We measured the I-V characteristics of a cell, similar results were obtained with different via sizes, due to the filamentary nature of resistance switching in ReRAM cell. As the voltage is swept from 0 V to a positive top electrode voltage, the device switches from a high resistive to a low resistive, or set. The low conducting, or reset, state can be restored by means of a negative voltage sweep where the switch-off of the device usually occurs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.326-326
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• 2014

It has been known since the mid 1960s that Ag can be photodissolved in chalcogenide glasses to form materials with interesting technological properties. In the 40 years since, this effect has been used in diverse applications such as the fabrication of relief images in optical elements, micro photolithographic schemes, and for direct imaging by photoinduced Ag surface deposition. ReRAM, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of a conductive filament in a solid electrolyte. Especially, Ag-doped chalcogenide glasses and thin films have become attractive materials for fundamental research of their structure, properties, and preparation. Ag-doped chalcogenide glasses have been used in the formation of solid electrolyte which is the active medium in ReRAM devices. In this paper, we investigated the nature of thin films formed by the photo-dissolution of Ag into Ge-Se glasses for use in ReRAM devices. These devices rely on ion transport in the film so produced to create electrically programmable resistance states [1-3]. We have demonstrated functionalities of Ag doped chalcogenide glasses based on their capabilities as solid electrolytes. Formation of such amorphous systems by the introduction of Ag+ ions photo-induced diffusion in thin chalcogenide films is considered. The influence of Ag+ ions is regarded in terms of diffusion kinetics and Ag saturation is related to the composition of the hosting material. Saturated Ag+ ions have been used in the formation of conductive filaments at the solid electrolyte which is the active medium in ReRAM devices. Following fabrication, the cell displays a metal-insulator-metal structure. We measured the I-V characteristics of a cell, similar results were obtained with different via sizes, due to the filamentary nature of resistance switching in ReRAM cell. As the voltage is swept from 0 V to a positive top electrode voltage, the device switches from a high resistive to a low resistive, or set. The low conducting, or reset, state can be restored by means of a negative voltage sweep where the switch-off of the device usually occurs.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.443-446
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• 2007

The novel blue light emitting material, 9,10-bis(3',5'-diphenylphenyl)anthracene (BDA) was synthesized by Suzuki coupling reaction and characterized by the measurements of 1H NMR, 13C NMR and FT-IR. The new anthracene derivative, which contains anthracene as a main core unit and 3',5'-diphenylphenyl group derivative as wings, has high fluorescence yield, good thermal stability, and high glass transition temperature at 188 oC. With the newly non-doped blue emitting material in the multilayer device structure, it was possible to achieve the current efficiency of 3.0 cd/A. The EL spectrum of the ITO/CuPc/α-NPD/BDA/Alq3/LiF/Al device showed a maximum wavelength (λmax) at 440 nm. The emitting color of device showed the blue emission (x,y) = (0.18,0.19) at 10 mA/cm2 in CIE (Commission Internationale de l'Eclairage) chromaticity coordinates.

• Advances in Energy Research
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• 제4권4호
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• pp.275-284
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• 2016

In the present work, ZnO nanoparticles (NPs) have been dispersed alone in the same solvent of the active layer for improving performance parameters of the organic solar cells. Different concentrations of the ZnO NPs have been blended inside active layer of the solar cell based on poly(3-hexylthiophene) (P3HT), which forms the hole-transport network, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which forms the electron-transport network. In the present investigations, the ZnO NPs may represent an efficient tool for improving light harvesting through light scattering inside active layer, electron mobility, and electron acceptance strength which tend to improve photocurrent and performance parameters of the investigated solar cell. The fill factor (FF) of the ZnO-doped solar cell increases nearly 14% compared to the non-doped solar cell when the doping is 50%. The present investigations show that ZnO NPs improve power conversion efficiency of the solar cell from 1.23% to 1.64% with increment around 25% that takes place after incorporation of 40% as a volume ratio of the ZnO NPs inside P3HT:PCBM active layer.

• 한국전기전자재료학회논문지
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• 제20권3호
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• pp.223-227
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• 2007

The effect of Eu contents on the ferroelectric properties of $Bi_{4-x}Eu_xTi_3 O_{12}$ (BET) thin films has been investigated. Bismuth Europium titanate thin films with a Eu contents were prepared on the $Pt/Ti/SiO_2/Si$ substrate by metal-organic decomposition technique. The structure and the morphology of the films were analyzed using X-ray diffraction (XRD) and field emission scanning microscopy (FE-SEM), respectively. From the XRD analysis, it was found that BET thin films have polycrystalline structure, and the layered-perovskite phase is obtained when the Eu contents exceeds 0.2 (x > 0.2). Also, the ferroelectric characteristics of the BET thin films were found to be dependent on the Eu content. Particularly, the BET films doped with x = 0.75 show better ferroelectric properties (remanent polarization 2Pr = 60.99 C/$cm^2$ and only a little polarization fatigue up to $3.5{\times}10^9$ bipolar switching cycling) than those doped with other Eu contents.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1720-1723
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• 2000

Boron doped conducting diamond thin film were grown on Si substrate by microwave plasma chemical vapor deposition from a gaseous feed of hydrogen, acetone/methanol and solid boron. The doping level of boron was controlled from 0ppm to $10^4$ppm (B/C). The Si substrate was tilted ca. 10$^{\circ}$ to make Si substrate have different height and temperature. Experimental results show that same condition but different temperature of Si substrate by height made different crystalline of diamond thin film. There were appeared 3$\sim$4 step of different crystalline morphology of diamond. To characterize the boron-doped diamond thin film, Raman spectroscopy was used for identification of crystallinity. To survey surface morphology, microscope was used. Grain size was changed gradually by different temperature due to different height. The Raman spectrum of film exhibited a sharp peak at 1334$cm^{-1}$, which is characteristic of crystalline diamond. The lower position of diamond film position, the more non-diamond component peak appeared near 1550$cm^{-1}$.