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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 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.
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 ㎓.
GaAs/AlAs 이중 장벽 공명 투과 구조의 전기적 특성의 온도 의존성
정관수,김순구,강태원,홍치유,조성환,김종호,백승도 慶熙大學校 材料科學技術硏究所 1991 材料科學技術硏究論集 Vol.4 No.-
Temperature dependences on current transport and peak to valley current ratio for GaAs/AlAs double barrier resonant tunneling structure have been studied. The transmission probability T (E, V) calculated by using an transfer matrix method. The calculation indicate that the double barrier resonant tunneling structures with small well width, and barrier thickness have larger peak to valley current ratio and peak current at high temperature, better temperature stability, and are suitable to operate at higher temperature. These results are good agreement with other published experiments.
실온에서의 이중 장벽 구조의 Resonant Tunneling
강태원,홍치우,김순구,엄기석,정관수,정창섭 慶熙大學校 材料科學技術硏究所 1988 材料科學技術硏究論集 Vol.1 No.-
AlAs/GaAn/AlAs resonant tunneling structures were grown by molecular beam epitaxy (MBE). In this work we observe the occurrence of resonant tunneling through a GaAs/AlAs double barrier at room temperature. A peak to valley current ratio of 1.4 was observed. And we aware of a small deviation in current-voltage characteristics over the sample.
Sodium-Disilicate 유리계내의 Fe이온에 대한 연구
홍치유,김순구,이철세,백승도 東國大學校 1990 論文集 Vol.29 No.-
In this paper, the Mo¨ssbauer spectra of(Na_2O.2SiO_2)_(100-x)(FeO)_x and ((Na_20.2SiO_2)??_x(Fe_2O_3)_x glass systems were invesigated at room temperature. The isomer shift quadrupole spitting and line width have a difference in quantity between the two glass system. As the content of Fe ion increase int eh two glass systems, the isomer shift and line width decrease, but the quadrupole splitting increases. the fe ion in the two glass systems are ferric state and play a role of glass modifier.
Intersubband Absorption in GaAs-AlGaAs Multiple Quantum Well Structure
Hong, C.Y.,Kim, S.K. 동국대학교 자연과학연구소 1989 자연과학연구 논문집 Vol.9 No.-
Infrared technique은 높은 반사율을 가진 기판위의 매우 얇은 막의 구조를 연구하는데 유용하게 사용되었다. MBE로 GaAs/AlGaAs 다양자 우물을 성장시켰고, 이 다양자우물의 absorption spectrum들을 실온에서 FTIR로 측정하였다. Absorption peak는 532cm에서 나타났고, 이것은 다양자 우물의 subband 간의 transition 에너지와 잘 일치한다. An infrared technique has been devised to study the structure of very thin films on substrates of high refractive index. We have grown GaAs/AlGaAs multiple quantum well structures by molecular beam epitaxy(MBE). The absorption spectra of that multiple quantum wells were measured at room temperature using a Fourier transform infrared spectrometer(FTIR). The absorption peak appeared at 532km, which was close of the intersubband transition energy in that multiple quantum wells.