100 nm T-gate의 InGaAs/InAlAs/GaAs metamorphic HEMT 소자 제작 및 특성에 관한 연구

김형상,신동훈,김순구,김형배,임현식,김현정,Kim, H.S.,Shin, D.H.,Kim, S.K.,Kim, H.B.,Im, Hyun-Sik,Kim, H.J. 한국진공학회 2006 Applied Science and Convergence Technology Vol.15 No.6

본 논문에서는 100 nm 게이트 길이를 갖는 InGaAs/InAlAs/GaAs MHEMT(metamorphic high electron mobility transistors)m의 DC와 RF 특성을 분석 하였다. 이중 노광 방법으로 ZEP520/P(MMA-MAA)/PMMA 3층 구조의 레지스터와 게이트 길이 100 nm인 게이트를 제작하였다. 게이트의 단위 폭이 $70\;{\mu}m$인 2개의 게이트와 길이가 100 nm로 제작된 MHEMT를 DC 및 RF특성을 조사하였다. 최대 드레인 전류 밀도는 465 mA/mm, 상호전달 컨덕턴스는 844 mS/mm이, RF 측정으로부터 전류 이득 차단 주파수는 192 GHz와 최대 진동주파수 310 GHz인 특성을 보였다. We present the DC and RF characteristics of 100 nm gate length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistors (MHEMTs). We fabricated the T-gate with 100 nm foot print by using a positive resist ZEP520/P (MMA-MAA)/PMMA trilayer by double exposure method. The fabricated 100 nm MHEMT with a $70\;{\mu}m$ unit gate width and two fingers were characterized through do and rf measurements. The maximum drain current density of 465 mA/mm and extrinsic transconductance $(g_m)$ of 844 mS/mm were obtained with our devices. From rf measurements, we obtained the current gain cut-off frequency $(f_T)$ of 192 GHz, and maximum oscillation frequency $(f_{max})$ 310 GHz.

상온 및 액체질소 온도에서 고속 중성자 조사된 원자로 압력 용기의 취화 현상에 관한 연구

김형배(H. B. Kim),김형상(H. S. Kim),김순구(S. K. Kim),신동훈(D. H. Shin),유연봉(Y. B. Yu),고정대(J. D. Ko) 한국자기학회 2005 韓國磁氣學會誌 Vol.15 No.2

The embrittlement of fast neutron-irradiated reactor pressure vessel (RPV) steels was investigated by X-ray diffraction patterns at room temperature and Mossbauer spectroscopy at room- and liquid nitrogen-temperature. Neutron fluence on the samples were 10¹², 10¹³, 10¹⁴, 10^(15), 10^(16), 10^(17), 10^(18) n/㎠. The X-ray diffraction patterns showed that the structure of the neutron unirradiated sample was bcc type, where as but the neutron irradiated samples with the fluence higher than 1017 n/㎠ were so severely damaged, that bcc type structure disappeared. The Mossbauer spectra of all samples showed superposition of two or more sextets. In this paper all Mossbauer spectra were fitted by three set of sextet. The isomer shift and quadrupole splitting values were found around zero. At liquid nitrogen temperature, magnetic hyperfine field and absorption area increase rapidly S1 sextet in the samples of 1017~1018 n/㎠ neutron fluences. And at room temperature, magnetic hyperfine field and absorption increased rapidly at S1 sextet in the samples of 1017~1018 n/㎠ neutron fluences. This rapid increase of magnetic hyperfine field and absorption area were inferred to be caused by the change of (56)^Fe, (55)^Mn into (57)^Fe due to by neutron irradiation.

100 ㎚ T-gate의 InGaAs/InAlAs/GaAs metamorphic HEMT 소자 제작 및 특성에 관한 연구

김형상(H. S. Kim),신동훈(D. H. Shin),김순구(S. K. Kim),김형배(H. B. Kim),임현식(Hyunsik Im),김현정(H. J. Kim) 한국진공학회(ASCT) 2006 Applied Science and Convergence Technology Vol.15 No.6

본 논문에서는 100 ㎚ 게이트 길이를 갖는 InGaAs/InAlAs/GaAs MHEMT(metamorphic high electron mobility transistors)m의 DC와 RF 특성을 분석 하였다. 이중 노광 방법으로 ZEP520/P(MMA-MAA)/ PMMA 3층 구조의 레지스터와 게이트 길이 100 ㎚인 T-게이트를 제작하였다. 게이트의 단위 폭이 70 m인 2개의 게이트와 길이가 100 ㎚로 제작된 MHEMT를 DC 및 RF특성을 조사하였다. 최대 드레인 전류 밀도는 465 ㎃/㎜, 상호전달 컨덕턴스는 844 mS/㎜이, RF 측정으로부터 전류 이득 차단 주파수는 192 ㎓와 최대 진동주파수 310 ㎓인 특성을 보였다. We present the DC and RF characteristics of 100 ㎚ gate length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistors (MHEMTs). We fabricated the T-gate with 100 ㎚ foot print by using a positive resist ZEP520/P(MMA-MAA)/PMMA trilayer by double exposure method. The fabricated 100 ㎚ MHEMT with a 70 ㎛ unit gate width and two fingers were characterized through dc and rf measurements. The maximum drain current density of 465 ㎃/㎜ and extrinsic transconductance (gm) of 844 mS/㎜ were obtained with our devices. From rf measurements, we obtained the current gain cut-off frequency (fT) of 192 ㎓, and maximum oscillation frequency (fmax) 310 ㎓.

소결온도 변화와 충전된 리튬이온 전지 LiFePO₄ 정극에 대한 뫼스바우어 효과

김태희(T. H. Kim),김형상(H. S. Kim),임현식(H. S. Im),유연봉(Y. B. Yu) 한국자기학회 2007 韓國磁氣學會誌 Vol.17 No.2

In this paper, we composed the LiFePO₄ for the reversible use as the replacement material of the Li ion batteries and confirmed the good quality of the structure of the samples with the sintering temperature 675 ℃, 750 ℃, and 800 ℃ for 30 hours at nitrogen atmosphere. We also investigated the size of the particles through SEM picture and the change of the sintering temperature and the Fe<SUP>+3</SUP> content after charging the materials with 1 V, 160 ㎃ and 3 V, 40 ㎃ for 3 hours by Mossbauer spectroscopy. Also we can observe the increase on the Fe<SUP>+3</SUP> content at the charge condition and the increase of the amount ratio of the Fe<SUP>+3</SUP> ion only in sintering temperature 675 ℃ according to the increase of the electric charge. We cannot observe the change of the Fe<SUP>+3</SUP> ion in sintering temperature 800 ℃ after charging.

Effect of Thermal Annealing on the Magnetic and the Optical Properties of (Ga1-xMnx)N Thin Films Grown on GaN Buffer Layers

H. C. Jeon,김형상,J. H. Jung,이정주,K. L. Wang,김문덕,M. K. Li,이승주,강태원,김태환,손윤,H. S. Kim 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.6

The annealing effect on the magnetic and the optical properties of (Ga$_{0.991}$Mn$_{0.009}$)N thin films grown on GaN buffer layers was investigated. The magnetization curves as functions of the magnetic field at 300 K showed that the magnetization in the (Ga$_{0.991}$Mn$_{0.009}$)N thin film annealed at 650 $^\circ$C was significantly enhanced by annealing in comparison with that of the as-grown film. The photoluminescence spectra at 4 K showed that the optical properties of the (Ga$_{0.991}$Mn$_{0.009}$)N thin film annealed at 650 $^\circ$C were improved due to annealing. These results can help to improve understanding of the thermal annealing effect on the magnetic and the optical properties of (Ga$_{1-x}$Mn$_x$)N thin films grown on GaN buffer layers.

Vanadium-phosphate 유리계에서의 철 이온에 관한 Mo¨ssbauer효과

洪致裕,金亨相,徐東滿 동국대학교 재료과학연구소 1983 材料科學硏究所 論文集 Vol.3 No.-

Mo¨ssbauer spectroscopy로서 V_2O_5·P_2O_5·Fe_2O_3 유리계에서 철의 위치, 원자가 상태 및 Mo¨ssbauer parameter를 측정하였다. 본 실험에서는 불순물로 산화철을 y-mole 비로 넣은 vanadium phosphate 유리를 시료로 사용하였으며 시료가 비정질임을 X-ray diffractometer로 확인하였고 γ線 source는 Rhodium에 dope된 ^57Co를 사용하였다. 유리의 성분비는 xV_2O_5·(1-x)P_2O_5·yFe_2O_3이고 x는 0.5, 0.6mole 비, y는 0.03, 0.05, 0.07mole 비로 하였다. 이와같이 준비된 혼합물은 탈수시키기 위하여 전기로 속에서 400℃로 약 30분간 유지한 후 공기 분위기하에서 약 2시간 동안 1000℃에서 용융시켜 시료를 택하였다. 유리의 Fe_2O_3 함량 증가에 따라서 I.S. 값은 증가하였고 Q.S. 값은 감소하는 경향을 나타내었다. 또한 Fe_2O_3 함량 증가에 따라 oxygen-polyhedra는 tetrahedral에서 octahedral로 변화함을 알 수 있었다. The Mo¨ssbauer parameters and the valence state of Fe ion and the site of ion in the Fe_2O_2-P_2O_5-V_2O_5 glasses were studied by the Mo¨ssbauer spectroscopy at room temperature. In this study the amorphous vanadium-phosphate glasses with y mole ratio ferric oxide as impurity were prepared. The structure of samples were investigated by X-ray diffractometer and γ-ray source is 5 mCi^57Co doped in rhodium. The base composition of the vanadium-phosphate glasses containing ferric oxide as follow; xV_2O_5·(1-x)P_2O_5·yFe_2O_3, where x is 0.5 and 0.6 mole ratio and y is 0.03, 0.05 and 0.07 mole ratio. The mixture were kept in the furnace at 400℃ for 30 minutes in order to dehydrate and were kept at the ambient temperature 1000℃ for the melting time, 2 hours.

The Mossbauer Effect of Fe Ion in Vanadium-Phosphate Glass System

Kim,H.S.,Hong,C.Y.,Seo,D.M. 동국대학교 자연과학연구소 1983 자연과학연구 논문집 Vol.3 No.-

Mossbauer spectroscopy로서 V₂O?ㆍP₂ㆍFe₂O₃유리계에서 철의 위치, 원자가 상태 및 Mossbauer parameter를 측정하였다. 본 실험에서는 불순물로 산화철을 y-mole비로 넣은 vanadium phosphate유리를 시료로 사용하였으며 시료가 비정질임을 X-ray diffractometer로 확인하였고 ι線 source는 Rhodium에 dope된 Co를 사용하였다. 유리의 성분비는 xVㅒ?(1-x)₂P₂O?.yFe₂O₃이고 x는 0.5,0.6mole 비, ysms 0.03, 0.05, 0.07mole 비로 하였다. 이와같이 준비된 혼합물은 탈수시키기 위하여 전기로 속에서 400℃로 약 30분간 유지한 후 공기 분위기하에서 약 2시간 동안 1000℃에서 용융시켜 시료를 택하였다. 유리의 Fe₂O₃함량 증가에 따라서 I.S. 값은 증가하였고 Q.S.값은 감소하는 경향을 나타내었다. 또한 Fe₂O₃함량 증가에 따라 oxygen-polyhedra는 tetrahedral에서 octahedral로 변화함을 알 수 있었다. The Mossbauer parameters and the valence state of Fe ion and the site of ion in the V₂O?ㆍP₂ㆍFe₂O₃glasses were studied by the Mossbauer spectroscopy at room temperature. In this study the amorphous vanadium-phosphate glasses with y mole ration ferric oxide as impurity were prepared. The structure of samples were investigated by X-ray diffractometer and ι-ray source is 5mCi Co doped in rhodium. The base composition of the vanadium-phosphate glasses containing ferric oxide as follow; xV₂O?(1-x)₂P₂O?.yFe₂O₃, where x is 0.5 and 0.6mole ration and y is 0.03, 0.05 and 0.07mole ration. The mixture were kept in the furcace at 400℃ for 30 minutes in order to dehydrate and were kept at the ambient temperature 1000℃ for the melting time, 2 hours. We found that isomer shift values tend to increase and quadrupole splitting values decrease as the Fe₂O₃concentration is increased. Also we found that the oxygen-polyhedra of iron chage from tetrahedral to octahedral as the Fe₂O₃concentration is increased.