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수직경사응고(VGF)법에 의한 Si 도핑 GaAs 단결정 성장시 $B_{2}O_{3}$ 첨가에 따른 캐리어 농도 변화
배소익,한창운,Bae, So-Ik,Han, Chang-Woon 한국결정성장학회 2009 韓國結晶成長學會誌 Vol.19 No.2
PBN 도가니를 이용하여 Si이 도핑된 GaAs 단결정을 수직경사 응고법으로 성장시켰다. PBN 도가니에 산화막인 $B_{2}O_{3}$의 양을 $0{\sim}0.2wt%$ 범위에서 변화시키면서, 성장 후 캐리어 농도를 측정하였다. $B_{2}O_{3}$ 첨가량이 증가함에 따라, 초기 0.1 정도의 Si 도판트의 편석계수는 0.01 부근까지 급격히 감소하고, 동시에 캐리어 농도도 감소하는 것을 알 수 있었다. 이는 성장도중 도판트인 Si이 $B_{2}O_{3}$과 반응하며 도너인 Si 양을 감소시키며, 동시에 억셉터인 B 양을 증가시키기 때문으로 보인다. 한편 PBN 도가니 내면에 얇은 유리질의 $B_{2}O_{3}$층 형성이 용이한 고온 산화막 처리가 결함감소에 효과적임을 확인하였다. Si-doped GaAs single crystals were grown by vertical gradient freeze using PBN crucibles. The amount of oxide layer $B_{2}O_{3}$ in PBN crucible was changed($0{\sim}0.2wt%$) and measured the concentration of carriers. The segregation coefficients of Si in GaAs melt decreased rapidly from initial 0.1 to 0.01 as the amount of $B_{2}O_{3}$ increases. At the same time, concentration of carriers was shown to decrease. It is likely that the reaction between dopant Si and $B_{2}O_{3}$ in GaAs melt results in the reduction of Si dopants(donor) while increase in the amount of boron(acceptor). The thin layer of $B_{2}O_{3}$ glass in PBN crucible was proved to be a better way to reduce defect formation rather than the total amount of $B_{2}O_{3}$.
우주, 군 응용을 위한 상업용 집적회로부품의 신뢰성 평가
천성일(Sung-Il Chan),한창운(Chang-Woon Han) 한국항공우주학회 2012 韓國航空宇宙學會誌 Vol.40 No.12
고 신뢰성을 요구하는 우주, 군 등과 같은 응용분야에 집적회로 사용에 대한 필요성이 증가하고 있다. 따라서 상업용(Commercial Off The Shelf) 집적회로부품에 대한 신뢰성 보증 요구조건과 실험규격에 대한 연구가 매우 필요하다. 본 연구에서는 ECSS(European Cooperation for Space Standardization) 품질규격과 MIL-STD-883(집적회로 시험방법)을 기초하여 상업용 집적회로부품의 신뢰성 검증(evaluation)을 위한 스크린(Screening) 실험방법을 검토하였다. 그리고 상업용 부품에 대한 스크린 시험절차와 검사방법을 제안하였다. 또한, 제안한 시험절차와 방법에 맞추어 상업용 Linear Bipolar 집적회로를 평가하였다. 시험결과 상업용 Linear Bipolar 제품이 고 신뢰성 활용을 위한 신뢰성 요구조건을 모두 만족하는 것을 확인하였다. Commercial Off the Shelf(COTS) Integrated circuits(ICs) are being increasingly considered for use in space and military applications. Therefore, There is a need to implement standard tests and requirements to ensure reliability of COTS ICs. This paper presents an overview of the ICs screen procedure and methods under the European Cooperation for Space Standardization (ECSS) and Tests Method Standard Microcircuits (MIL-STD-883). We describes the COTS ICs screen test guidelines that are mainly focused after encapsulating. In addition, COTS linear bipolar IC is investigated to evaluate the reliability requirements. The experiment results showed that COTS IC is satisfied with high reliability requirements.
열충격 사이클에 따른 SnAgCu 솔더별 솔더 접합부의 신뢰성 및 계면반응
오철민 ( Chul Min Oh ),박노창 ( No Chang Park ),한창운 ( Chang Woon Han ),방만수 ( Man Soo Bang ),홍원식 ( Won Sik Hong ) 대한금속·재료학회 2009 대한금속·재료학회지 Vol.47 No.8
Pb-free solder has recently been used in electronics in efforts to meet environmental regulations, and a number of Pb-free solder alloy choices beyond the near-eutectic SnAgCu solder are now available. With increased demand for thin and portable electronics, the high cost of alloys containing significant amounts of silver and their poor mechanical shock performance have spurred the development of low Ag SnAgCu solder, which provides improved mechanical performance at a reasonable cost. Although low Ag SnAgCu solder exhibits significantly higher fracture resistance under high-strain rates, little thermal fatigue data exist for this solder. Therefore, it is necessary to investigate thermal fatigue reliability of low Ag SnAgCu solder under variation of thermal stress in order to allow its implementation in electronic products with high reliability requirements. In this study, the reliability of Sn0.3Ag0.7Cu(SAC0307), a low Ag solder alloy, is discussed and compared with that of Sn3Ag0.5Cu(SAC305). Three sample types and six samples size are evaluated. Mechanical properties and microstructure of the solder joint are investigated under thermal shock cycles. It was observed that the mechanical strength of SAC0307 dropped slightly with thermal cycling relative to that of SAC305. This reveals that the failure mode of SAC0307 is different from that SAC305 under this critical condition.