• 제목/요약/키워드: Energy Gap

검색결과 1,658건 처리시간 0.033초

Optical energy band gap of the conductive $AgGaSe_2$ layers

  • You, Sang-Ha;Hong, Kwang-Joon
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 추계학술대회 논문집
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    • pp.46-46
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    • 2009
  • The photoconductive $AgGaSe_2$(AGS) layers were grown by the hot wall epitaxy method. The AGS layer was confirmed to be the epitaxially grown layer along the <112> direction onto the GaAs(100) substrate. The band-gap variation as a function of temperature on AGS was well fitted by $E_8(T)=1.9501-8.37{\times}10^{-4}T^2/(T+224)$. The band-gap energy of AGS obtained at 293 K was determined to be 1.8111 eV.

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Investigation of Sensitivity Distribution in THz Metamaterials Using Surface Functionalization

  • Cha, Sung Ho;Park, Sae June;Ahn, Yeong Hwan
    • Current Optics and Photonics
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    • 제3권6호
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    • pp.566-570
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    • 2019
  • To investigate dependence of the sensitivity of THz metamaterials on the position of target dielectric materials, we functionalized the metamaterial gap with an adhesive polymer. A shift in resonance frequency occurs when polystyrene microbeads are deposited in the gap of the metamaterial's metal resonator pattern, while little change is observed when they are deposited on other areas of the metasurface. A two-dimensional mapping of the sensitivity, with a grid size of 1 ㎛, is obtained from a finite-difference time-domain simulation: The frequency shift is displayed as a function of the position of a target dielectric cube. The resulting sensitivity distribution clearly reveals the crucial role of the gap in sensing with metamaterials, which is consistent with the electric field distribution near the gap.

Electronic Properties and Conformation of$\pi$-Conjugated Molecules with Phenyl and Heterocyclic Group

  • Eunho Oh;Kim, Cheol-Ju
    • Journal of Photoscience
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    • 제7권2호
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    • pp.67-71
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    • 2000
  • A quantum-chemical investigation on the conformations and electronic properties of trans(diphenyl-diheterocyclic) ethenes(t-PHEs) as building block for fully $\pi$-conjuated polymer are performed in order to display the effects of heterocyclic ring substitution. Structures for the molecules, t-PHEs were fully optimized by using semiempirical AM1, PM3 methods, and ab initio HF methods, with 6-31G basic set. The potential energy curves with respect to the change of single are obtained by using ab initio HF/6-31G basic set. The curves are not similar shapes in the molecules with respect to heterocyclic rings. It is shown that the steric repulsion interactions between phenyl ring and heterocyclic ring are subjected to different type with the respect to each heterocyclic ring. Electronic properties of the molecules were molecules were obtained by applying the optimized structures and selected geometries to the extended Huckel method. To investigate the change of HOMO-LUMO gap with respedt to the torsion angle, we select the optimized structures. By using the results, the dependency of conjugation for the energy gaps is analyzed. For t-PHE the energy gap increase up to 0.52 eV compared with its planar structure. In the cases of t-PHE and t-PHE, the energy gap increase by 1.29 and 1.15 eV, respectively, compared with its planar structure.

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경수로 핵연료 열-구조 연계 해석을 위한 다차원 간극 열전도도 모델 개발 (Development of Multidimensional Gap Conductance Model for Thermo-Mechanical Simulation of Light Water Reactor Fuel)

  • 김효찬;양용식;구양현
    • 대한기계학회논문집A
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    • 제38권2호
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    • pp.157-166
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    • 2014
  • 경수로 핵연료가 원자로내에서 연소되는 동안 핵연료 펠릿에서부터 피복관까지 온도해석은 핵연료 안전 해석에 있어 중요한 요소이며, 경수로 핵연료 온도 해석을 하기 위해서는 간극 모델 개발이 필수적이다. 간극 열전도도는 특성상 간극 두께값에 의존적이게 되며 이러한 특성으로 인해 다차원 간극 열전도도 모델이 비선형적 거동을 보인다. 본 연구에서는 선형화된 다차원 간극 열전도도 모델 개발을 위해 가상 연결 간극 요소를 제안하였다. 제안된 간극 연결 요소에 간극 열전도도를 적용하기 위해 등가 열전달 계수를 정의하였다. 제안된 모듈을 평가하기 위해 상용코드 ANSYS APDL 을 이용하여 열-구조 연계 해석 모듈을 구현하였으며, 다양한 예제를 통해 정확성과 수렴성을 평가하였다.

모형 로켓 연소실에서 배플형 분사기의 간극에 의한 음향 감쇠 효과에 관한 수치적 연구 (A Numerical Study on Acoustic Damping Induced by Gap between Baffled Injectors in a Model Rocket Combustor)

  • 손채훈;이중연
    • 한국추진공학회지
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    • 제11권3호
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    • pp.35-42
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    • 2007
  • 로켓 엔진의 음향 불안정을 제어하기 위해 모형 연소실에 배플형 분사기가 장착된 경우의 음향 감쇠 특성을 수치해석적으로 조사하였다. 기존에 보고된 배플형 분사기의 효용성을 확인하였고 분사기간 간극이 존재할 때 음향 감쇠 효과가 증대되는 메커니즘을 규명하였다. 여러 가지 크기의 간극에 따라 음향학적 감쇠능력을 조사하였고, 본 연소실에서는 0.1 mm 정도의 간극에서 최적의 감쇠능력을 가짐을 알 수 있었다. 음향 감쇠 효과가 증대되는 메커니즘을 규명하기 위해, 분사기 사이의 간극에 따른 에너지 소산율과 와도를 계산하였고, 소산율 변화 추이와 감쇠인자 변화 추이가 유사함을 알았다. 이를 통해, 간극에 의한 에너지 소산의 종대로 음향 감쇠 효과가 증가함을 알았다.

Photoreflectance에 의한 반절연성 GaAs의 띠간격 에너지(Eo)측정 (Band-gap energy (Eo) measurements of semi-insulating GaAs by photoreflectance)

  • 배인호;김말문;이정열;김인수;김기홍
    • E2M - 전기 전자와 첨단 소재
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    • 제7권6호
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    • pp.490-495
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    • 1994
  • We investigated photoreflectance of semi-insulating GaAs with respect to modulation sources, that is, modulation beam intensity, modulation frequency, temperature, and thickness of sample. PR spectra by each modulation source turned out to be signals of low electric field third differential, and band gap values of sample were fitted by least square root method for Aspnes' theoretical equation.

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화학수송법으로 성장한 $Cd_4GeSe_{6}$$Cd_{4}GeSe_{6}$ : $CO^{2+}$ 단결정에서 에너지 띠 간격의 온도의존성 및 열역학함수 추정 (Temperature Dependence of Energy Gap and Thermodynamic Function Properties of Undoped and Co-doped $Cd_{4}GeSe_{6}$ Sing1e Crystals by Chemical Transport Reaction Method)

  • 김남오;김형곤;김덕태;현승철;오금곤
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제52권2호
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    • pp.85-90
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    • 2003
  • In this work $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}$ : $Co^{2+}$ single crystals were grown by the chemical transport reaction method and the structure of $Cd_{4}GeSe_{6}$ and $Cd_{4}GeSe_{6}$ : $Co^{2+}$ single crystals were monoclinic structure. The temperature dependence of optical energy 9ap was fitted well to Varshni equation. Also, the entropy, enthalpy and heat capacity were deduced from the temperature dependence of optical energy gap.

$In_2S_3$ : $Co^{2+}$ 단결정의 광학적 에너지 갭 특성 (Optical energy gap properties of $Co^{2+}$ -doped $In_2S_3$ single crystal)

  • 김형곤;김남오;최영일;이경섭
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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    • pp.42-46
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    • 2000
  • ${\beta}{\cdot}In_2S_3$${\beta}{\cdot}In_2S_3:Co^{2+}$$In_2S_3$+S+ZnS를 출발물질로 하여 ($ZnCl_2+I_2$)를 수송매체로 사용한 chemical transport reaction method로 성장시켰다. 성장된 단결정은 tetragonal structure를 갖고 298K에서 indirect optical energy gap은 2.240eV, 1.814eV로 각각 주어졌고, direct optical energy gap은 2.639eV, 2.175eV로 각각 주어졌다. ${\beta}{\cdot}In_2S_3:Co^{2+}$ single crystal에서 impurity optical absorption peak가 나타났으며, 이들 peaks의 origin은 $Co^{2+}(Td)$ ion의 energy level 간의 electron transition임을 crystal field theory를 적용하여 규명하였다.

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Bridgman 방법 의해서 성장된 GaSe 단결정의 광학적인 특성 (OPTICAL PROPERTIES OF GaSe SINGSE CRYESTALS by BRIDGMAN TECHNIQUE)

  • 이우선;정용호;김남오;김형곤
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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    • pp.239-241
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    • 1996
  • The energy gap of GaSe:$Er^{3+}$(5mol%) single crystals grown by the Bridgman technique displaced a direct energy gap at 1.79 eV and an indirect energy gap at 1.62 eV at $300^{\circ}K$ with the addition of Erbium. Also, an impurity optical absorption peak was found to have occurred at $6505\;cm^{-1}$. The peak identified the origin of the electronic transitions between the energy levels of $Er^{3+}$ ions when the addition of dopant.

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