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갈륨비소(110) 표면상의 리튬 원자의 흡착에 관한 연구
송기문 건국대학교 자연과학연구소 1998 建國自然科學硏究誌 Vol.9 No.2
이종 원자가 접근하기에 에너지적으로 가장 안정한 갈륨비소(110) 표면상의 4가지 위치에 대하여 리튬 원자를 수직으로 접근시키면서 각 리튬 높이에 대한 Hartree-Fock 에너지 계산을 실시하였다. 에너지적으로 가장 안정된 리튬 높이에서 4차 다체섭동이론 수준의 자세한 갈륨비소(110)표면과 리튬 원자간의 상호작용을 조사하였다. 계산에서, 갈륨,비소,리튬의 Hay-Wadt 유효핵전위를 사용하였다. 리튬 원자의 흡착은 LiGa5As4H12 시스템으로 구성된 위치(Site II)에서 에너지적으로 가장 안정함을 보였다. 리튬 원자로부터 갈륨비소(110) 표면으로 많은 전하이동이 있고, 갈륨비소(110) 표면에서는 갈륨 원자가 전하를 잃고 비소 원자가 전하를 얻는다. Different possible adsorption sites of lithium atoms on a GaAs (110) surface have been studied using ab initio self-consistent Hartree-Fock energy cluster calculations followed by detailed correlation investigations at the level of fourth-order many body perturbation theory. The Hay-Wadt effective core potentials have been applied to represent the core of lithium, gallium, and arsenic atoms. We find that Li atom adsorption at a site modeled with a LiGa5As4H12 system is the most favored energetically. Significant charge transfer from the Li atom to the GaAs (110) surface is also found to occur, with Ga atoms losing charge and As atoms gaining charge.
하이브리드 자동차용 저전압 DC/DC 컨버터 제어 방법
문정송(Jung-Song Moon),이정효(Jung-Hyo Lee),이택기(Taeck-Kie Lee),원충연(Chung-Yeun Won) 전력전자학회 2010 전력전자학술대회 논문집 Vol.2010 No.7
Low Voltage DC/DC Converter(LDC) is the power conversion unit for suppling the power to the auxiliary battery and the electric loads on vehicle. LDC has the capabilities of stability and efficient control method so that the electric loads are fully functional. This paper proposes a control method based on one PI-controller and verifies the stable performance from simulation.
First-principle Study for Al<SUB>x</SUB>Ga<SUB>1-x</SUB>P and Mn-doped AlGaP₂ Electronic Properties
Byung-Sub Kang,Kie-Moon Song 한국자기학회 2015 Journal of Magnetics Vol.20 No.4
The ferromagnetic and electronic structure for the AlxGa1-xP and Mn-doped AlGaP₂ was studied by using the self-consistent full-potential linear muffin-tin orbital method. The lattice parameters of un-doped AlxGa1-xP (x= 0.25, 0.5, and 0.75) were optimized. The band-structure and the density of states of Mn-doped AlGaP₂ with or without the vacancy were investigated in detail. The P-3p states at the Fermi level dominate rather than the other states. Thus a strong interaction between the Mn-3d and P-3p states is formed. The ferromagnetic ordering of dopant Mn with high magnetic moment is induced due to the (Mn-3d)-(P-3p)-(Mn-3d) hybridization, which is attributed by the partially filled P-3p bands. The holes are mediated with keeping their 3d-characters, therefore the ferromagnetic state is stabilized by this double-exchange mechanism.
Chalcopyrite AlGaAs₂, (Al,Ga)As 반도체내 Mn의 강자성
강병섭(Byung-Sub Kang),송기문(Kie-Moon Song),이행기(Haeng-Ki Lee) 한국자기학회 2020 韓國磁氣學會誌 Vol.30 No.5
We investigated the electronic and magnetic properties for a diluted magnetic semiconductor of 3d-metal Mn-doped chalcopyrite (CH) AlAs, GaAs, and AlGaAs₂ semiconductors by using the first-principle calculations. The CH-AlGaAs₂:Mn without the defects exhibits the ferromagnetic and half-metallic states. For the system of CH-Al(Ga,Mn)As₂, the ferromagnetism with high magnetic moment of Mn is induced from the exchange couplings between Mn-3d and As-4p bands. The partially unoccupied majority-spin Mn- 3d and As-4p states are induced. Thus the Mn moments couple to holes by an on-site exchange interaction due to the overlap of the hole wave-function with the Mn-3d (or As-4p) electrons. The electronic and magnetic properties for Mn-doped CH-AlAs and CHGaAs systems were compared with that of CH-Al(Ga,Mn)As₂. It is noticeable that high magnetic moment induces from the characteristics by holes-mediated double-exchange coupling.
HFCVD법으로 증착된 다이아몬드 박막의 이온주입 효과
백홍구,심재엽,송기문 건국대학교 자연과학연구소 1999 建國自然科學硏究誌 Vol.10 No.1
다이아몬드 에미터는 디바이스 안정성이나 내구성에서 탁월한 성능을 가지므로 합성 다이아몬드 박막에 대한 관심이 크다. 이온주입의 효과가 고온 휠라멘트 화학기상증착법(HFCVD)법으로 성장된 다이아몬드 박막의 다이아몬드 품질에 미치는 영향을 연구하였다. 여기서는 붕소와 인의 이온을 고 에너지로 주입시켜, 이온 주입 전후의 다이아몬드의 구조적 변화를 분석하였다. Raman 스펙트럼 측정에 의하면 붕소 이온 주입된 시료는 많은 흑연 성분을 포함한 미약한 다이아몬드의 특성을 보이고 있으나, 인 이온 주입된 시료는 다이아몬드 구조를 나타내지 않는다. Auger 스펙트럼을 분석하면 붕소와 인 이온을 주입한 시료 모두가 표면에 심한 이온주입 훼손이 생겨 다이아몬드 특성을 잃은 것을 알 수 있다. There has been much interest in synthetic thin film diamond as the emitter materials because the diamond emitter can carry a crucial performance for the device stability and durability. Diamond films grown by hot filament chemical vapor deposition (HFCVD) have been studied to investigate the effect of ion implantation on diamond qualities. Here the diamond films were implanted with boron and phosphorus ions and analyzed their structural changes by implantations. From Raman spectra, the boron ion implanted samples still show a weakened diamond peak with high graphite component while the phosphorus ion implanted sample loses diamond structure. On tile other hand. their AES spectra at surface do not exhibit an obvious diamond shoulder, indicating the surface of ion implanted samples damaged by high fore implantation.
Investigation of the transition between glow and streamer discharges in atmospheric air
Choi, Jai Hyuk,Lee, Tae Il,Han, Inho,Baik, Hong Koo,Song, Kie Moon,Lim, Yong Sik,Lee, Eung Suok IOP Pub ; American Institute of Physics 2006 Plasma sources science & technology Vol.15 No.3
<P>Generally, the parameter <I>p</I> · <I>d</I> (pressure × gap distance) in dielectric barrier discharge (DBD) controls the electrical breakdown and also the plasma characteristics. We investigated the optimum plasma transition <I>p</I> · <I>d</I> by controlling the pressure. To find the transition <I>p</I> · <I>d</I> (<I>p</I> · <I>d</I><SUB>tr</SUB>) condition, optical emission spectroscopy (OES) was used to measure emission spectra from the DBD. All <I>p</I> · <I>d</I> data were normalized by the second positive system of nitrogen molecules, the wavelength of which was 337.1 nm. Then we compared the relative intensities of species generated during the discharge by OES analysis. Species selected for comparison were the first negative system (FNS) of nitrogen molecules (391.4 nm) and atomic oxygen spectra (777.1 nm). Experimental results showed that relative intensities were almost constant as <I>p</I> · <I>d</I> decreased, but at specific <I>p</I> · <I>d</I> data, the intensity started to increase. The increase in FNS of nitrogen molecules means not only an increase in electron energy but also a change in the plasma mode, streamer to glow transition. In the case of DBD using alumina with 1 mm thickness applied ac power, the plasma transition occurred at the 1 Torr cm condition.</P>