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수소 플라즈마 처리를 거친 ZnO 박막에 대한 PL 연구
조재원,이석주,Cho, Jaewon,Rhee, Seuk Joo 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.1
The physical effects of H-plasma treatment on ZnO thin film have been studied using photoluminescence(PL) spectroscopy. Four characteristic peaks have been identified: (i) $D^0X$ peak (neutral donor-bound exciton), showing relatively small integrated intensity after H-plasma treatment, indicates that H-plasma passivates the neutral donors in ZnO at low temperatures. The rapid decrease in the integrated intensity of the peak as the temperature goes up is considered to be due to the ionization of neutral donors. (ii) H-related complex-bound exciton peak appears at the low temperatures (10 K~80 K) after H-plasma treatment, showing the same thermal evolution as $D^0X$ peak. (iii) FX (free exciton) peak starts to show up at 60 K and grows more and more as the temperature goes up, which is considered to be related to the increase in free electron concentration in the film. (iv) violet band is intensified after H-plasma, which means more defects and impurities are generated by H-plasma process.
조재원,Cho, Jaewon 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.2
The optical properties of ZnO thin film have been studied using photoluminescence(PL) spectroscopy with the change of sample temperatures from 10 K to 290 K. The spectrum at 10 K showed the characteristic emission lines of ZnO which were as follows: free exciton(FX) at 3.369 eV, neutral donor-bound exciton($D^0X$) at 3.360 eV, two electron satellite(TES) at 3.332 eV, $D^0X$-1LO at 3.289 eV, and donor-acceptor pair(DAP) transiton at 3.217 eV. From the spectral evolution with temperatures, two features could be identified as temperature went higher: (1) the bound excitons changed gradually into free excitons, (2) DAP turned into free electron-acceptor transition(e,$A^0$). The PL intensity of free exciton increased with the increase of temperatures, which was accompanied by the decrease of the intensity of bound excitions and bound excition-related transitons such as TES and $D^0X$-1LO. At 80 K DAP transition disappeared, while (e,$A^0$) transition started to appear at 30 K.
조재원(Jaewon Cho),이재열(Jae-Yel Yi) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.1
여러 가지 방법의 plasma 표면 처리와 산화 공정이 SiO₂-Si(100) 계면에 미치는 물리적 영향을 angle resolved uv-photoelectron spectroscopy(ARUPS)를 이용하여 연구하였다. 표면은 ex situ 방법과 함께 in situ 수소 플라즈마를 이용하여 처리되어 졌으며, 이것은 고진공 고온 열 처리 방법과 비교되어졌다. ARUPS 빛띠 상에 나타난 산화물 가전자 띠에 대한 특징적인 peak 위치는 표면 처리 및 산화 공정 방법에 따라 이동하였다. 이러한 peak의 이동은 Si에서의 띠휨에 의한 것으로 분석되어졌다. 또한 peak 이동의 원인으로 Si-SiO₂ 계면에 형성된 결점과 표면 처리 공정에 따라 달라지는 표면 거칠기 등을 고려할 수 있었다. 여러 공정에 대한 ARUPS 결과를 비교함으로써 Si-SiO₂ 계면 결합이 표면 처리 및 산화 방법에 깊이 관련되어 있음을 결론지을 수 있었다. 산소 plasma 공정은 가장 작은 band bending을 보여주었다. The effect of different plasma surface preparation and oxidation processes for the formation of SiO₂-Si(100) interfaces was studied using angle resolved uv-photoelectron spectroscopy. The surface preparation processes included ex situ preclean as well as in situ hydrogen plasma, which were compared to the processes of UHV annealing at high temperature. The spectral position of the oxide valence band features, with respect to the Fermi level, were found to shift according to the different processes of surface preparation and oxidation. The shifts were analyzed in terms of band bending in the Si. Origins of the spectral shifts were considered to include defects at the SiO₂-Si interfaces and surface morphology(roughness) dependent on the surface preparation processes. From comparison of the ARUPS results of the various processes, it was concluded that the interface bonding of the silicon oxide-Si(100) was dependent on the oxidation process and the surface preparation. The O-plasma process showed the lowest band bending.
산소 플라즈마 처리후의 이차전자방출계수(γ)를 이용한 MgO 보호막의 일함수(φW) 변화
정재천,유세기,조재원,Jeong, Jae-Cheon,Yu, SeGi,Cho, Jaewon 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.3
The changes in secondary electron emission coefficient(${\gamma}$) and work function($\Phi$$_{\omega}$) have been studied on the surface of MgO protective layer aster plasma(Ar. $O_2$) treatment using ${\gamma}$-focused ion beam (${\gamma}$-FIB) system. The values of ${\gamma}$ varied as follows: $O_2$-treated MgO > Ar-treated MgO > Non-treated MgO, and the work functions varied in the reverse order. The result indicates that both the physical etching and the chemical reaction of $O_2$-plasma removed the contaminating materials from the surface of MgO.
Hyung-Seop Shin(신형섭),Juho Yeo(여주호),Jaewon Cho(조재원),Eunsu Min(민은수),Un-Bong Baek(백운봉) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
Recently, ANU group has established a simple screening technique for hydrogen embrittlement compatibility of steels, which is adopting an in-situ small-punch (SP) test method and corresponding to the ‘external hydrogen’ condition, and proposed a characterizing factor which is suitable for the SP test. The technique is based on the quantitative evaluation of the hydrogen embrittlement (HE) behaviors of various structural steels for hydrogen energy facilities. To investigate the HE compatibility of metallic materials, the in-situ SP tests were carried out under a high-pressure hydrogen gas environment and at the temperature ranges sensitive to HE. Through the measurement of the reduction of thickness (ROT) at the fractured part of the specimen after SP tests under both H2 and inert gas environments, the relative reduction of thickness (RRT) due to HE can be obtained. The RRT has a similar physical meaning to the relative reduction of area (RRA) obtained by the conventional slow strain-rate tensile test (SSRT), since both factors are based on the ductility induced under hydrogen environments. In this study, it is tried to investigate the hydrogen embrittlement (HE) behaviors of pipeline steels and welds by the in-situ SP test. The ductility-based RRT obtained by in-situ SP tests was used to quantify the HE sensitivity of the base metal and welds under various test conditions corresponding to practical use environments of hydrogen devices. This study will contribute to confirm the validity of in-situ SP tests as a simple test method for the quantitative evaluation of the HE susceptibility of pipeline steel welds.
스마트 임산부복 (Lily Kickee): 태아의 태동을 감지하여 시각적으로 보여주는 웨어러블 장치
전빈(Jeon Been),박상후(Park Sanghoo),조재원(Cho Jaewon),배병철(Bae Byung-chull),조준동(Cho Jun-dong) 한국HCI학회 2014 한국HCI학회 학술대회 Vol.2014 No.12
본 연구는 스마트 임산부복으로써 태아의 태동을 감지하여 시각적으로 보여주는 웨어러블 컴퓨터를 제작하고 사용성 평가까지 함을 목적으로 한다. 프로토타입 제작에 앞서 사전조사를 하였고, 그 결과를 토대로 태동을 알려주는 직관적인 모습을 태아의 발자국 모양으로 형상화하였다. 릴리패드 아두이노, 전도성 실, 압력센서 그리고 다양한 LED 를 사용하여 프로토타입을 제작하고 그 이후 사용성 평가를 진행하였다. 50 명을 대상으로 만족감, 착용감, 실용성, 직관성 그리고 공감 정도 평가를 한 결과, 스마트 임산부복을 착용한 후 태아와의 공감 정도가 높아졌다는 점에서 본 연구는 의의가 있다. This study purposed to develop smart maternity wear, which is a wearable computer that senses and visualize fetal movements, and to evaluate its usability. Before making the prototype, we conducted a preliminary survey and, based on the results, visualized fetal movements intuitively in the form of fetal footprint. The prototype was built with Lilypad Arduino, conductive thread, pressure sensor, and various LED’s, and then its usability was tested. When satisfaction, fitness, practicality, intuitiveness, and sympathy were evaluated with 50 participants, the use of the smart maternity wear was found to enhance the level of empathy and increase communication among the family members.