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  • Title/Summary/Keyword: 이종재료 접합

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Tensile-Shear Fatigue Strength of Self-Piercing Rivets Joining Dissimilar Metal Sheets (이종재료 Self-Piercing Rivets 접합부의 인장-전단 피로강도)

  • Kang, Se Hyung;Kim, Taek Young;Oh, Man Jin;Kim, Ho Kyung
    • Journal of the Korean Society of Safety
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    • v.30 no.4
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    • pp.1-7
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    • 2015
  • Self-piercing riveting (SPR) process is gaining popularity due to its many advantages. The SPR does not require a pre-drilled hole and has capability to join a wide range of similar or dissimilar materials and combinations of materials. This study investigated the fatigue strength of self-piercing rivet joint with aluminum alloy (Al-5052) and steel (SPCC) sheets. Static and fatigue tests on tensile-shear specimens were conducted. From the static strength aspect, the optimal punching force for the specimen with upper SPCC (U.S) sheet and lower aluminum alloy(L.A) sheets was 34 kN. During static test the specimens fractured in pull-out fracture mode due to influence of plastic deformation of joining area. There was a relationship between applied load amplitude Pamp and number of cycles N ; Pamp=19588N0.211f and Pamp=4885N0.083f for U.S-L.A and U.A-L.S specimens, respectively. U.A-L.S fatigue specimens failed due to fretting crack initiation around the rivet neck between upper and lower sheets.

Polarization of Stimulated Emission from Optically Pumped AIGaN/GaInN DH (AIGaN/GaInN DH의 광여기 유도방출광의 편광)

  • ;;H. Amano;I. Akasaki
    • Proceedings of the Materials Research Society of Korea Conference
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    • 1994.11a
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    • pp.98-98
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    • 1994
  • 최근 청색반도체레이저의 실현을 위하여 ZnSe가 대표하는 II-Ⅵ족 화합물반도체와 Gan가 대표하는 III족 질화물반도체분야에서 집중적인 연구가 이루어지고 있으며, 아직까지 실용화 되지 않고 있는 청색반도체레이저의 출현에 대하여 많은관심이 모아지고 있다. III족 질화물반도체는 InM(Eg:1.9eV)부터 AIN(Eg: 6.2eV)에 이르기까지 전 조성영역에서 완전한 고용체를 이루며, 실온에서 직접천이형 에너지 대구조를 가지므로 청색 혹은 자외영역에서 동작하는 발광소자를 제작하는데 있어 유망시 되고 있는 소재이다. 특히 GaN와 InN의 3원흔정인 GaInN를 활성층으로 이용하면 그 발전파장을 370nm부터 650nm까지 즉 가시 전 영역으로부터 근 자외영역을 포함할 수 있게 된다. 이 연구에서는 AIGaN/GaInN 이중이종접합(DH) 구조의 고아여기에 의한 유도방출고아의 편광 특성을 조사하였다. 유기금속기상에피텍셜(MOVPE)법으로 성장한 AIGaN/GaInN DH 구조의 표면에 수직으로 펄스 발진 질소레이저(파장: 337.1cm, 주기 10Hz, 폭: 8nsec) 빔을 조사하고 DH구조의 단면으로부터의 유도방출광을 편광기를 통과 시킨 후 스펙트럼을 측정하였다. 입사고아 밀도가 증가함에 따라 약 402nm의 파장에서 유도발출에 의한 가도가 큰 피크가 나타났고, 그 반치폭은 약 18meV이었다. 실온에서 AIGaN/GaInN DH 구조로 부터의 유도방출에 필요한 입사광밀도의 임계치는 약 130㎾/cm2이었다. 한편 편광각이 90일때는 발광스펙트럼의 강도가 매우 낮고 단지 자연방출에 의한 스펙트럼만이 나타났다. 편광각이 0일 때 최대의 방출광 강도를 나타내었으며, 편광각이 -90로 회전함에 따라 발고아강도의 강도가 감소하였다. 이와 같은 결과는 광여기에 의하여 AIGaN/GaInN DH 로 부터의 유도방출광이 GaInN활성층의 단면에 평행한 전기장의방향으로, 즉 TE모드로 선형적으로 편광됨을 의미한다. AIGaN/GanN DH 로 부터의 유도방출이 선형적으로 TE모드로 편광되는 것은 이 구조를 이용한 청색 및 자외선 반도체 레이저다이오드의 실현에 매우 유익한 것이다.

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Photoinduced Hydrophilicity of Heterogeneous TiO2/WO3 Double Layer Films (이종 접합 구조를 갖는 TiO2/WO3 이중 박막의 광유기 친수 특성)

  • Oh, Ji-Yong;Lee, Byung-Roh;Kim, Hwa-Min;Lee, Chang-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.11
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    • pp.715-720
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    • 2015
  • The photoinduced hydrophilicity of TiO2/WO3 double layer films was fabricated by using a conventional rf-magnetron sputtering method. The photoinduced hydrophilic reaction of the TiO2 surface was enhanced by the presence of WO3 under the TiO2 layer by irradiation of a 10 W cylindrical fluorescent light bulb. However, when the TiO2 and WO3 layers were separated by an insulating layer, the surface did not appeared high hydrophilic, under the same light bulb. The enhanced photoinduced hydrophilic reaction can be explained by the charge transfer between TiO2 and WO3 layers. It was also demonstrated that visible light passing through the TiO2 layer could excite WO3. Thus, visible light can be used for the hydrophilic reaction in the present TiO2/WO3 system.

Relative Absorption Edges of GaN/InGaN/GaN Single Quantum Wells and InGaN/GaN Heterostructures by Metalorganic Chemical Vapor Deposition (유기금속화학기상증착법으로 성장된 GaN/InGaN/GaN 단양자 우물층과 InGaN/GaN 이종접합 구조의 광학적 특징)

  • Kim, Je-Won;Son, Chang-Sik;Jang, Yeong-Geun;Choe, In-Hun;Park, Yeong-Gyun;Kim, Yong-Tae;Ambacher, O.;Ctutzmann, M.
    • Korean Journal of Materials Research
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    • v.9 no.1
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    • pp.42-45
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    • 1999
  • The room temperature optical transmission spectra of GaN /InGaN/GaN single quantum wells (SQW) and InGaN/GaN heterostructures grwon by low pressure metalorganic chemical vapor deposition have been measured. The dependence of the absorption edges of the GaN/InGaN/GaN SQW on the well width has been determined from the transmission spectra. The result shows that the absorption edge of GaN/InGaN/GaN SQW shifts towards lower energy as increasing the well width. The dependence of the absorption edges of the InGaN/GaN heterostructures on InN mole fraction has also been determined from the transmission spectra. The result is compared with calculated values obtained from Vegards's laws. Our result shows a good agreement with the calculated values.

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Photoelectrochemical Properties of a Cu2O Film/ZnO Nanorods Oxide p-n Heterojunction Photoelectrode for Solar-Driven Water Splitting (물분해용 Cu2O 박막/ZnO 나노막대 산화물 p-n 이종접합 광전극의 광전기화학적 특성)

  • Park, Junghwan;Kim, Hyojin;Kim, Dojin
    • Korean Journal of Materials Research
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    • v.28 no.4
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    • pp.214-220
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    • 2018
  • We report on the fabrication and photoelectrochemical(PEC) properties of a Cu2O thin film/ZnO nanorod array oxide p-n heterojunction structure with ZnO nanorods embedded in Cu2O thin film as an efficient photoelectrode for solar-driven water splitting. A vertically oriented n-type ZnO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method and then a p-type Cu2O thin film was directly electrodeposited onto the vertically oriented ZnO nanorods array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were characterized using X-ray diffraction and scanning electron microscopy as well as Raman scattering. The PEC properties of the fabricated Cu2O/ZnO p-n heterojunction photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the Cu2O/ZnO photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., 0.77mA/cm2 at 0.5 V vs Hg/HgCl2 in a 1mMNa2SO4 electrolyte, revealing an effective operation of the oxide heterostructure. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs Hg/HgCl2, which made the device self-powered. The observed PEC performance was attributed to some synergistic effect of the p-n bilayer heterostructure on the formation of a built-in potential, including the light absorption and separation processes of photoinduced charge carriers.

Comparison of Dry Etching of GaAs in Inductively Coupled BCl3 and BCl3/Ar Plasmas (BCl3BCl3/Ar 유도결합 플라즈마에 따른 GaAs 건식식각 비교)

  • ;;;;;S.J Pearton
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.62-62
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    • 2003
  • 고밀도 유도결합 플라즈마(high density inductively coupled plasma) 식각은 GaAs 이종접합 양극성 트랜지스터(HBTs)와 고속전자 이동도 트랜지스터(HEMTs)와 같은 GaAs 기반 반도체의 정교한 패턴을 형성하는데 더욱 많이 이용되고 있다 본 연구는 고밀도 플라즈마 소스(source)인 평판형(planar) 고밀도 유도결합 플라즈마 식각장치를 이용하여 BCl3BCl3/Ar 가스에 따른 GaAs 식각결과를 비교 분석하였다. 공정변수는 ICP 소스 파워를 0-500W, RIE 척(chuck) 파워를 0-150W, 공정압력을 0-15 mTorr 이었다. 그리고 가스 유량은 20sccm(standard cubic centimeter per minute)으로 고정시킨 상태에서 Ar 첨가 비율에 따른 GaAs의 식각결과를 관찰하였다. 공정 결과는 식각률(etch rate), GaAs 대 PR의 선택도(selectivity), 표면 거칠기(roughness)와 식각후 표면에 남아 있는 잔류 가스등을 분석하였다. 20 BCl3 플라즈마를 이용한 GaAs 식각률 보다 Ar이 첨가된 (20-x) BC13/xAr 플라즈마의 식각률이 더 우수하다는 것을 알 수 있었다. 식각률 증가는 Ar 가스의 첨가로 인한 GaAs 반도체와 Ar 플라즈마의 충돌로 나타난 결과로 예측된다. BCl3BC13/Ar 플라즈마에 노출된 GaAs 반도체 모두 표면이 평탄하였고 수직 측벽도 또한 우수하였다. 그리고 표면에 잔류하는 성분은 Ga와 As 이외에 Cl2 계열의 불순물이 거의 발견되지 않아 매우 깨끗함을 확인하였다. 이번 발표에서는 BCl3BCl3/Ar 플라즈마를 이용한 GaAs의 건식식각 비교에 대해 상세하게 보고 할 것이다.

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Metal Oxide-Based Heterojunction Broadband Photodetector (산화물 반도체 기반의 이종접합 광 검출기)

  • Lee, Sang-eun;Lee, Gyeong-Nam;Ye, Sang-cheol;Lee, Sung-ho;Kim, Joondong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.3
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    • pp.165-170
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    • 2018
  • In this study, double-layered TCO (transparent conductive oxide) films were produced by depositing two distinct TCO materials: SnO2 works as an n-type layer and ITO (indium-doped tin oxide) serves as a transparent conductor. Both transparent conductive oxide-films were sequentially deposited by sputtering. The electrical and optical properties of single-layered TCO films (SnO2) and double-layered TCO (ITO/SnO2) films were investigated. A TCO-embedding photodetector was realized through the formation of an ITO/SnO2/pSi/Al layered structure. The remarkably high rectifying ratio of 400.64 was achieved with the double-layered TCO device, compared to 1.72 with the single-layered TCO device. This result was attributed to the enhanced electrical properties of the double-layered TCO device. With respect to the photoresponses, the photocurrent of the double-layered TCO photodetector was significantly improved: 1,500% of that of the single-layered TCO device. This study suggests that, due to the electrical and optical benefits, double-layered TCO films are effective for enhancing the photoresponses of TCO photodetectors. This provides a useful approach for the design of photoelectric devices, including solar cells and photosensors.

Development of SiGe Heterostructure Epitaxial Growth and Device Fabrication Technology using Reduced Pressure Chemical Vapor Deposition (저압화학증착을 이용한 실리콘-게르마늄 이종접합구조의 에피성장과 소자제작 기술 개발)

  • Shim, K.H;Kim, S.H;Song, Y.J;Lee, N.E;Lim, J.W;Kang, J.Y
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.4
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    • pp.285-296
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    • 2005
  • Reduced pressure chemical vapor deposition technology has been used to study SiGe heterostructure epitaxy and device issues, including SiGe relaxed buffers, proper control of Ge component and crystalline defects, two dimensional delta doping, and their influence on electrical properties of devices. From experiments, 2D profiles of B and P presented FWHM of 5 nm and 20 nm, respectively, and doses in 5×10/sup 11/ ∼ 3×10/sup 14/ ㎝/sup -2/ range. The results could be employed to fabricate SiGe/Si heterostructure field effect transistors with both Schottky contact and MOS structure for gate electrodes. I-V characteristics of 2D P-doped HFETs revealed normal behavior except the detrimental effect of crystalline defects created at SiGe/Si interfaces due to stress relaxation. On the contrary, sharp B-doping technology resulted in significant improvement in DC performance by 20-30 % in transconductance and short channel effect of SiGe HMOS. High peak concentration and mobility in 2D-doped SiGe heterostructures accompanied by remarkable improvements of electrical property illustrate feasible use for nano-sale FETs and integrated circuits for radio frequency wireless communication in particular.

Characterization of ZnO/MgZnO heterojunction grown by thermal evaporation (열기상증착법으로 성장된 ZnO/MgZnO 이종접합 나노막대의 물성분석)

  • Kong, Bo-Hyun;Jun, Sang-Ouk;Kim, Yung-Yi;Kim, Dong-Chan;Cho, Hyung-Koun;Kim, Hong-Seung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.11-11
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    • 2006
  • ZnO는 넓은 밴드갭(3.37eV)과 큰 액시톤(exciton) 결합에너지(60meV)를 가지는 II-VI족 화합물 반도체이다[1]. 이와같은 특성은 상온에서도 높은 재결합 효율이 기대되는 엑시톤 전이가 가능하여 자발적인 발광특성 및 레이저 발진을 위한 낮은 임계전압을 가져 일광효율이 큰 장점이 있다. 최근에는 ZnO의 전기적, 광학적, 자기적 특성을 높이기 위해 doping에 대한 연구가 많이 보고 되고 있다. 이중 ZnO내에 Mg을 doping하게 되면 Mg 조성에 따라 밴드갭이 3.3~7.7eV까지 변하게 된다. 그러나 이원계 상평형도에 따라 ZnO내에 고용될 수 있는 MgO의 고용도는 4at% 이하이다. 이는 ZnO는 Wurtzite 구조이고, MgO는 rocksalt 구조로 각각 결정구조가 다르기 때문이다. 본 연구는 열기상증착방법(thermal evaporation)으로 ZnO 템플레이트를 이용하여 MgZnO 나노막대를 합성하였고, Zn와 Mg의 서로 다른 녹는점을 이용해 2-step으로 성장을 하였다. 합성은 수평로를 사용하였으며, 반응온도 550, 700C로 2-step으로 하였으며, 소스로 사용된 Zn(99.99%)과 Mg(99.99%) 분말을 산소를 직접 반응시켜 합성하였다. Ar 가스와 O2 가스를 각각 운반가스와 반응가스로 사용하였다. ZnO 템플레이트 위에 성장시킨 1차원 MgZnO 나노구조의 형태 및 구조적 특성을 FESEM과 TEM으로 분석하였다. 그리고 결정학적 특성은 XRD를 이용해 분석하였다.

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Electrical Characteristics of the Packaged SiGe Hetero-Junction Bipolar Transistors Fabricated with Various Conditions of the Collector Formation (패키지된 실리콘-게르마늄 이종접합 바이폴라 트랜지스터의 콜렉터 형성 조건에 따른 전기적 특성)

  • Lee, Seung-Yun;Lee, Sang-Heung;Kim, Hong-Seung;Park, Chan-U;Kim, Sang-Hun;Lee, Ja-Yeol;Sim, Gyu-Hwan;Gang, Jin-Yeong
    • Korean Journal of Materials Research
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    • v.12 no.6
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    • pp.470-475
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    • 2002
  • The effects of the conditions of the collector formation on electrical characteristics of the packaged SiGe hetero-junction bipolar transistors (HBT) were investigated. While the DC characteristics of SiGe HBTs such as IV characteristic, forward current gain, Early voltage, and breakdown voltage were hardly changed after packaging, the AC characteristics such as fτandfmax were degraded severely. With the rise of the collector concentration, the break-down voltage decreased but the fτ increased. Additionally, β and fτ values were kept high in the range of elevated collector current due to the increase of the critical current density for the onset of the Kirk effect. The devices As implanted before the collector deposition showed lower breakdown voltage and higher fτ than the others, which seems to be originated from the As up-diffusion resulting in the thinner collector.