• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
• /
• pp.247-250
• /
• 1999

We have performed $^{63,65}$Cu nuclear quadrupole resonance (NQR) measurements on Zn and Ni doped YBa$_2Cu_3O_7$ (YBa$_2Cu_{3-x}M_xO_7$, M=Zn or Ni, x = 0.00 ${\sim}$ 0.09). Doping effects are markedly different in relaxation rates as well as in superconducting transition temperatures. Both the spin-lattice and the spin-spin relaxation rates decrease for Zn doped YBCO. However, those increase for Ni doped YBCO. This contrast in local electronic dynamics provides a clear microscopic evidence that Zn forms no local moment, while Ni develops a local moment. Consequently, the antiferromagnetic spin fluctuation is suppressed by Zn doping whereas it is preserved by Ni doping.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 추계학술대회 초록집
• /
• pp.63.2-63.2
• /
• 2011

결정질 실리콘 웨이퍼를 이용한 고효율 태양전지를 제작하기 위해서는 반드시 고려해야 할 주요 인자들이 있다. 그 중에서도 Base resistivity, Thickness, Doping concentration, Texture size, Texture angle등의 주요 인자를 PC1D 시뮬레이션 프로그램을 이용하여 최적화 해 보았다. 그 결과, Base resistivity값은 낮을수록 좋으나 지나치게 낮을 경우 재결합으로 인해 효율이 떨어지기 때문에 Base resistivity = $1{\Omega}{\cdot}cm$에서 최대 효율을 얻을 수 있었다. 또한, Thickness는 두꺼울수록 R=${\rho}$(L/A)의 식에 의해 직렬저항이 증가하여 효율이 감소하므로 Thickness = $200{\mu}m$ 정도가 적정 값임을 확인할 수 있었다. Doping concentration의 경우 높을수록 재결합으로 인해 효율이 떨어지며 Doping concentration = $3.69{\times}10^{-20}cm^{-3}$에서 가장 좋은 효율을 보였다. Textrure size와 Textrure angle은 그 값이 클수록 빛의 흡수 정도가 증가해 효율이 증가함을 볼 수 있었고 Textrure size = $2{\sim}4{\mu}m$, Texture angle = $79^{\circ}$에서 높은 효율을 보여주었다. 이와 같은 조건에서 고효율 태양전지를 제작을 위한 시뮬레이션을 한 결과, 16.23%의 변환효율을 얻을 수 있었다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.168-168
• /
• 2012

본 연구에서는 Molybdenum oxide (MoOx)-doped 4,4',4"-tris[2-naphthyl(amino)] triphenylamine(2-TNATA)의 P-doping에 의한 hole ohmic contact과 fullerene (C60)/lithium (LiF)의 electron ohmic contact에 의한 All Ohmic contact를 이용한 유기 발광 다이오드 (OLEDs)의 광저항 특성의 향상을 설명한다. 이 소자의 성능은 MoOx-doped 2-TNATA의 두께와 도핑농도에 큰 영향을 받는다. glass/ITO/MoOx-doped 2-TNATA (100 nm)/Al 구조의 소자에서 MoOx-doped 2-TNATA 도핑 농도가 25%에서 75%로 증가할수록 hole only device의 hole ohmic 특성이 향상됐다. 그 이유는 p-type doping effect 때문이다. 또한 photoemission spectra 분석결과, p-type doping effect는 hole-injecting barrier 높이는 낮추고, hole conductivity는 향상되었다. 이것은 2-TNATA에 도핑된 MoOx의 전하전송 콤플렉스의 형성으로 hole carrier의 수가 증가하여 발생되었다. MoOx-doped 2-TNATA의 hole ohmic contact과 fullerene (C60)/lithium fluoride (LiF)의 electron ohmic contact 으로 구성된 glass/ITO/MoOx-doped 2-TNATA (75%, 60 nm)/NPB (10 nm)/Alq3 (35 nm)/C60 (5 nm)/LiF (1 nm)/Al (150 nm)의 소자구조는 6,4V에서 127,600 cd/m2 최대 휘도와 약 1,000 cd/m2에서 4.7 lm/W의 높은 전력 효율을 보여준다.

• Electronic Materials Letters
• /
• 제14권6호
• /
• pp.733-738
• /
• 2018

Undoped and Mn-doped $In_2O_3$ films were prepared by radiofrequency magnetron sputtering technique. The effects of Mn doping on the structural and optical properties of as-prepared films were investigated using X-ray diffraction, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. Mn doping can enhance the intensity of (222) peak in Mn-doped $In_2O_3$ thin film, indicating Mn dopant promotes preferred orientation of crystal growth along (222) plane. XPS analyses revealed that the doped Mn ions exist at + 2 oxidation states, substituting for the $In^{3+}$ sites in the $In_2O_3$ lattice. UV-Vis measurements show that the optical band gap $E_g$ decreases from 3.33 to 2.87 eV with Mn doping in $In_2O_3$, implying an increasing sp-d exchange interaction in the film. Our work demonstrates a practical means to manipulate the band gap energy of $In_2O_3$ thin film via Mn impurity doping, and significantly improves the photoelectrochemical activity.

• 정보저장시스템학회논문집
• /
• 제1권1호
• /
• pp.93-98
• /
• 2005

Rewritable optical disk is one of the essential data storage media in these days, which takes advantage of the different optical properties in the amorphous and crystalline states of phase change materials. As well known, data transfer rate is one of the most important parameter of the phase change optical disks, which is mostly limited by the crystallization speed of recording media. Therefore, we doped Sn/Bi to $Ge_2Sb_2Te_5$ alloy in order to improve the crystallization speed and investigated the dependence of phase change characteristics on Sn/Bi doping concentration. The Sn/Bi doped $Ge_2Sb_2Te_5$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, UV-visible spectrophotometer, electron probe microanalysis (EPMA), inductively coupled plasma mass spectrometer (ICP-MS) and atomic force microscopy (AFM). Optimum doping concentration of Bi and Sn were 5${\~}$6 at.$\%$ and the minimum time for crystallization was below than 20 ns. This improvement is correlated with the simple crystalline structure of Sn/Bi doped $Ge_2Sb_2Te_5$ and the reduced activation barrier arising from Sn/Bi doping. The results indicate that Sn/Bi might play an important role in the transformation kinetics of phase change materials..

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
• /
• pp.110-111
• /
• 2006

In this paper, we investigated resistance characteristic of chalcogenide material for next generation ReRAM nonvolatile memory device with laser irradiation. A AES is used to test Ag doping ratio into a As-Ge-Se-S thin film. A sample resistance was observed in real time with He-Ne laser(632.8nm). As a result, resistance of thermal treated As-Ge-Se-S thin film was $500{\Omega}$ which is smaller than initial $1.3M{\Omega}$. A resistance of non-treated Ag/As-Ge-Se-S thin film was $200{\Omega}$ which is lower than $35M{\Omega}$.

• Applied Microscopy
• /
• 제47권1호
• /
• pp.19-28
• /
• 2017

Since graphene was discovered in 2004, two-dimensional (2D) materials have been actively studied. Especially, 2D transition metal dichalcogenides (TMDs), such as $MoS_2$ and $WS_2$, have been the subject of significant research because of their exceptional optical, electrical, magnetic, catalytic, and morphological properties. Therefore, these materials are expected to be used in a variety of applications. Furthermore, tuning the properties of TMDs is essential to improve their performance and expand their applications. This review classifies the various doping methods of 2D TMDs, and it summarizes how the dopants interact with the materials and how the performance of the materials improves depending on the synthesis methods and the species of the dopants.

• Journal of Electrical Engineering and Technology
• /
• 제8권6호
• /
• pp.1497-1502
• /
• 2013

Recently, the junctionless (JL) transistors realized by a single-type doping process have attracted attention instead of the conventional metal-oxide-semiconductor field-effect transistors (MOSFET). The JL transistor can overcome MOSFET's problems such as the thermal budget and short-channel effect. Thus, the JL transistor is considered as great alternative device for a next generation low standby power silicon system. In this paper, the JL FinFET was simulated with a three dimensional (3D) technology computer-aided design (TCAD) simulator and optimized for DC characteristics according to device dimension and doping concentration. The design variables were the fin width ($W_{fin}$), fin height ($H_{fin}$), and doping concentration ($D_{ch}$). After the optimization of DC characteristics, RF characteristics of JL FinFET were also extracted.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.471-471
• /
• 2013

Highly stable and high performance amorphous oxide semiconductor thin film transistors (TFTs) were fabricated using 4-mercaptophenol (4MP) doped ZnO by atomic layer deposition (ALD). The 4 MP concentration in ZnO films were varied from 1.7% to 5.6% by controlling Zn: 4MP pulses. The carrier concentrations in ZnO thin films were controlled from $1.017{\times}10^{20}$/$cm^3$ to $2,903{\times}10^{14}$/$cm^3$ with appropriate amount of 4MP doping. The 4.8% 4MP doped ZnO TFT revealed good device mobility performance of $8.4cm^2V-1s-1$ and on/off current ratio of $10^6$. Such 4MP doped ZnO TFTs were stable under ambient conditions for 12 months without any apparent degradation in their electrical properties. Our result suggests that 4 MP doping can be useful technique to produce more reliable oxide semiconductor TFT.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.1034-1037
• /
• 2002

In this study, we fabricated red organic electrolu-minescent device with a doping material (DCJTB), and The cell structure used ITO:indium tin oxide $[20{\Omega}]$/CuPc:Hole injection layer 20nm/NPB: Hole transfer layer 40nm/$Alq_3$ (host) + DCJTB(1% or 3%) (guest) Emitting layer 40nm/$Alq_3$ : Electron transfer layer 30nm/Al :Cathode layer 150nm. the luminescent layer consisted of a host material. 8-hydrozyquinoline aluminum $(Alq_3)$, and DCJTB dye as the dopant. a stable red emission (chromaticity coordinates : x=0.64, y=0.36) was obtained in this cell with the luminance range of $100-600cd/m^2$. we study the electrical and optical properties of devices.