http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
IB - Al - VIB₂ 및 IB - Al - VIB₂ : Co²+ 결정의 광학적 특성연구
김화택(Wha-Tek Kim),김창대(Chang-Dae Kim),윤창선(Chang-Sun Yum),진문석(Moon-Seog Jin),최성휴(Sung-Hyu Choi) 한국진공학회(ASCT) 1995 Applied Science and Convergence Technology Vol.4 No.3
I^B-Al-VI^B₂ 및 I^B-Al-VI^B₂ : Co^(2+) 결정을 고순도 원소를 출발 물질로 하고 iodine을 수송 매체로 사용하여 chemical transport reaction method로 성장시켰다. 성장된 결정의 결정구조는 chalcopyrite 구조였으며, energy gap은 direct band gap으로 3.514~1.813 eV 정도로 주어졌으며, cobalt를 불순물로 첨가할 때 energy gap은 감소하였다. I^B-Al-VI^B₂ : Co²+ 결정에서 첨가된 cobalt가 모체 결정의 T_d symmetry site에 Co²+ ion으로 위치하여, Co²+ ion의 energy 준위 사이의 전자전이에 기인하는 불순물 광흡수 peaks가 나타났다. 이 불순물 광흡수 peaks에 결정장 이론을 적용하여 구한 lst-order spin-orbit coupling parameter(λ)는 -183~-189 ㎝-¹ 정도였고, 2nd-order spin-orbit coupling parameter(P)는 225~239㎝-¹ 정도였으며, crystald parameter(D_q)는 328~385㎝-¹, Racah parameter(B)는 531~552㎝-1¹ 정도였다. Crystals of I^B-Al-VI^B₂ and I^B-Al-VI^B₂ : Co²+ were prepared by the chemical transport reaction method using iodine as a transporting agent from high-purity constituent elements as starting materials. It has been found that these crystals have a chalcopyrite structure and the direct band gaps are ranging from 1.813 to 3.514 eV. When a cobalt is introduced as an impurity, it has been observed that the direct band gap decreases. We observed impurity optical absorption peaks due to the electronic transitions of Co²+ ions with T_d symmetry sites of I^B-Al-VI^B₂, host lattices. On the basis of our experimental results, we calculated various parameters using crystal-field theory. The values are given by -183~-189 ㎝-¹ for the 1st-order spin-orbit coupling parameter, 225-239 ㎝-¹, for the 2nd-order spin-orbit coupling parameter, 328-385 ㎝-¹ for the crystal-field parameter, and 531-552 ㎝-¹ for the Racah parameter, respectively.
김화택(Wha-Tek Kim),윤상현(Sang-Hyun Yun),현승철(Seung-Cheol Hyun),김미양(Mi-Yang Kim),김용근(Yong-Geun Kim),김형곤(Hyung-Gon Kim),최성휴(Sung-Hyu Choe),윤창선(Chang-Sun Yoon),정해문(Hae-Mun Jeong) 한국진공학회(ASCT) 1994 Applied Science and Convergence Technology Vol.3 No.1
SbSBr, BiSBr, SbSBr : Co, BiSBr : Co, SbSBr : Ni 및 BiSBr : Ni 단결정을 수직 Bridgman 방법으로 성장시켰다. 성장된 단결정의 구조는 orthorhombic 구조이며, 광학적 energy band gap 구조는 간접전이형이었고, energy gap의 온도의존성은 일차 및 이차 상전이점에서 anomalous한 특성이 나타났다. 불순물로 첨가한 cobalt와 nickel은 T_d 대칭점에 Co^(2+) ion, Co^(3+) ion 및 Ni^(2+) ion으로 위치하며, 이들 ion의 energy 준위간의 전자전이에 의하여 불순물 광흡수 peak들이 나타난다. SbSBr, BiSBr, SbSBr : Co, BiSBr : Co, SbSBr : Ni and BiSBr : Ni single crystals were grown by the vertical Bridgman technique. The grown single crystals were crystallized in orthorhombic. The optical energy band gap of them was the indirect structure, and the temperature dependence of the energy gap showed anomalous properties at the first order phase transition and the second order one. Cobalt and nickel doped with a impurity are sited at the T_d symmetry points as the states of Co^(2+) or CO^(3+) and Ni^(2+) ions.
김화택(Wha-Tek Kim),윤창선(Chang-Sun Yun),김창대(Chang-Dae Kim),최성휴(Sung-Hyu Choi),진문석(Moon-Seog Jin),박태영(Tae-Young Park),박광호(Kwang-Ho Park) 한국진공학회(ASCT) 1997 Applied Science and Convergence Technology Vol.6 No.1
순수한 ZnAl₂S₄, ZnAl₂Se₄, CdAl₂S₄, CdAlSe₄ 및 cobalt와 erbium을 불순물로 첨가한 이들 단결정을 화학수송법으로 성장시켰다. 성장된 단결정의 결정구조, 격자상수, 광학적 energy gap, photoluminescence 특성 등을 측정하여 광학적 전이 기구를 규명하였다. Undoped, cobalt-doped and erbium-doped ZnAl₂S₄, ZnAl₂Se₄, CdAl₂S₄, and CdAl₂Se₄ single crystals were grown by the chemical transport reaction method. The crystal structures, the lattice constants, the optical energy gaps, and the photoluminescence properties of these single crystals were investigated. Also, the optical transition mechanisms by the impurities of cobalt and erbium were identified from these results.
Pb<sub>1-x</sub>Cd<sub>x</sub>I<sub>2</sub> 단결정의 구조적 광학적 특성 연구
송호준,최성길,김화택,Song, Ho-Jun,Choi, Sung-Gill,Kim, Wha-Tek 한국재료학회 2002 한국재료학회지 Vol.12 No.11
$Pb_{1-x}$ $Cd_{x}$ $I_2$ (x=0.0, 0.2, 0.5, 0.7, 0.9, 1.0) single crystals were grown by using Bridgman method and their structural and optical properties were investigated from the measurement of X-ray diffraction, optical absorption and photoluminescence. As-grown single crystals have hexagonal closed packed layered structure. The values of lattice constant c decrease with increasing composition x. Direct and indirect transition optical energy band gaps are calculated from optical absorption spectra measured at room temperature. They increase exponentially from 2.3eV to 3.2 eV with increasing composition x. The energies of photoluminescence peak due to donor bound exciton measured at 6K increase with increasing composition . However, the peak energies of donor-acceptor pair (DAP) are independent of the optical energy band gaps of $Pb_{1-x}$/$Cd_{x}$ $I_2$ single crystals.
CuGaSe₂ 단결정의 Photoluminescence 특성
진문석(Moon-Seog Jin),김화택(Wha-Tek Kim) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.3
CuGaSe₂ 단결정을 고순도(99.9999%)의 Cu, Ga, Se 원소를 화학조성비로 칭량한 후 Se을 3 mole % 과잉으로 첨가하여 합성된 ingot를 사용하여 iodine(99.9999%)을 수송매체로 한 화학수송 법으로 성장시켰다. 성장된 단결정은 검정색을 띠고 있었으며, 10K에서 optical energy gap 이 1.755eV로 주어졌다. Ar-ion laser로 여기시켜 측정한 photoluminescence(PL) 스펙트럼으로부터 1.667eV, 1.085eV, 1.025 eV에 위치한 세 개의 PL peak를 얻었다. Thermally stimulated current(TSC) 측정에서 0.660eV, 0.720eV의 deep donor level을 관측하였으며, PL peak intensity의 thermal quenching으로 구한 activation energy는 0.010eV이었다. CuGaSe₂ 단결정에서 PL mechanism은 edge emission 및 donor-acceptor pair recombination임을 규명했다. CuGaSe₂ single crystal was grown by the chemical transport reaction method using the iodine (99.999%) as the transport agent, where the starting material was the ingot synthesized by the melt grown technique with the excess selenium of 3 mole % plus the high purity elements Cu, Ga and Se (99.9999%) in stoichiometry, The as-grown single crystal showed the black color and had the optical energy gap of 1.755eV at 10K. From the photoluminescence spectra measured at 10K using the Ar-ion laser (488 nm-line) as the exciter, we obtained the three peaks located at 1.667eV, 1.085 eV and 1.025eV. Also, the deep donor levels located at 0.660eV and 0.720eV below the conduction band were obtained from the TSC measurement, and the shallow acceptor level located at 0.010 eV upper the valence band was obtained from the activation energy by the thermal quenching of the photoluminescence intensity. As the result, we identify that the three photoluminescence peaks are attributed to the edge emission and the donor-acceptor pair recombinations.
오석균,현승철,윤상현,김화택,김형곤,최성휴,윤창선,권숙일,Oh, Seok-Kyun,Hyun, Seung-Cheol,Yun, Sang-Hyun,Kim, Wha-Tek,Kim, Hyung-Gon,Choe, Sung-Hyu,Yoon, Chang-Sun,Kwun, Sook-Il 한국진공학회 1993 Applied Science and Convergence Technology Vol.2 No.2
SbSI : V, SbSeI : V, BiSI : V, BiSeI : V, SbSI : Cr, SbSeI : Cr, BiSI : Cr, BiSeI : Cr, SbSI : Ni, SbSeI : Ni, BiSI : Ni, 및 BiSeI : Ni 단결정을 고순도(99.9999%)의 성분원소에 혼합물을 투명석 영관내에 넣고, $1{\times}10^{-6}mmHg$의 진공에서 봉입하여 합성한 ingot를 사용하여, 수직 Bridgman 방법으로 성장시켰다. 성장된 단결정의 구조는 orthorhombic 구조이며, 광학적 energy band gap 구조는 간접전이형 이었고, energy gap의 온도의존성은 상전이에 관계되는 2개의 변곡점이 나타났으며, 연속된 영역에서는 Varshni 방정식을 만족하였다. 첨가한 3d 불순문(V, Cr, Ni)은 모결정의 $T_d$ 대칭을 갖는 주격자점에 +2가 ion으로 위치하며, 이들 ion의 energy 준위간의 전자전이에 의하여 불순물 광흡수 peak가 나타난다. Single crystals, SbSI : V, SbSeI : V, BiSI : V, BiSeI : V, SbSI : Cr, SbSeI : Cr, BiSI : Cr, BiSeI : Cr, SbSI : Ni, SbSeI : Ni, BiSI : Ni, and BiSeI : Ni were grown by the vertical Bridgman method. It is found that the grown single crystals have an orthorhombic structure and the indirect optical transitions. The temperature dependence of energy gap shows the two reflection point related with the phase transitions and is well fitted with Varshni equation in the continuous region. The optical absorption peaks due to the doped impurities (V, Cr and Ni) are respectively attributed to the electron transitions between the split energy levels of $V^{+2}$, $Cr^{+2}$ and $Ni^{+2}$ ions sited at $T_d$ symmetry of the host lattice.
MgGa₂-xInxSe₄ 단결정을 이용한 광전반도체소자 제작과 그 특성 연구
김형곤(Hyung-Gon Kim),김화택(Wha-Tek Kim) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.1
MgGa_(2-x)In_xSe₄ single crystal을 bridgman technique로 성장시켰다, 성장된 단결정은 rhombohedral 구조를 가지고 있었으며, lattice constant는 a=3.950~4.070 Å, c=38.89~39.50 Å으로 주어졌고, 높은 photoconductivity를 가지고 있었다. 이 단결정의 energy gap은 2.20~1.90 eV이었고, photoconductivity spectrum에 peak의 energy는 2.31~2.01 eV로 주어졌으며, photoconductivity의 time constant는 0.24~0.34 sec로 주어졌다. MgGa_(2-x)In_xSe₄ single crystals grown by the bridgman technique. The crystal structure of these compounds determined by X-ray diffraction analysis was rhombohedral structure with lattice constants a=3.950~4.070 Å, c=38.89~39.50 Å for MgGa_(2-x)In_xSe₄ single crystals. Also, these crystals have high photoconductivity. The direct band gaps of these compounds are found to be 2.20~1.90 eV at room temperature, and the peak energy of photoconductivity spectrum, 2.31~2.01 eV, and the time constants of photoconductivity, 0.24~0.34 sec.
Cd₄SnSe6 및 Cd₄SnSe6 : Co²+ 單結晶의 光學的 特性
한석룡(Suk-Ryong Hahn),김화택(Wha-Tek Kim) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.4
화학수송법으로 Cd₄SnSe_6 및 Cd₄SnSe_6 : Co²+ 단결정을 성장시켰다. 성장된 단결정은 monoclinic structure를 갖고 있으며, 광학적 energy gap은 직접전이형으로 293K에서 Cd₄SnSe_6 단결정의 경우 1.68eV이고, Cd₄SnSe_6 : Co²+ 단결정의 경우 1.50eV 이다. Cd₄SnSe_6: Co²+ 단결정에서 cobalt 불순물에 의한 불순물 광흡수는 4879 ㎝^(-1), 5392 ㎝^(-1), 6247 ㎝^(-1)에서 나타났으며, 이들 peak는 Cd₄SnSe_6 단결정의 T_d symmetry site에 위치한 Co²+ ion의 energy 준위 사이의 전자전이에 의한 optical absorption이다. Cd₄SnSe_6 and Cd₄SnSe_6: Co²+ single crystals were grown by the chemical transport reaction (CTR) method. The grown single crystlas crystallize in the monoclinic structure and have the direct band gaps. The energy gaps of them are 1.68eV for Cd₄SnSe_6 and 1.50 eV for Cd₄SnSe_6 : Co²+ at 293K. The impurity optical absorption peaks due to cobalt doped with impurity appear at 4879 ㎝^(-1), 5392 ㎝(-1) and 6247 ㎝^(-1), and are attributed to the electron transitions between the split energy levels of Co²+ ion sited at T_d symmetry of Cd₄SnSe_6 single crystal.
Photoluminescence Properties of Ni - doped and Undoped CdGa₂Se₄ Single Crystals
김창대(Chang-Dae Kim),정해문(Hae-Mun Jeong),신동호(Dong-Ho Shin),김화택(Wha-Tek Kim) 한국진공학회(ASCT) 1992 Applied Science and Convergence Technology Vol.1 No.2
Iodine 화학수송법으로 성장한 Ni-doped CdGa₂Se₄와 undoped CdGa₂Se₄ 단결정의 PL 및 PLE 스펙트럼을 조사하였다. Undoped CdGa₂Se₄ 단결정의 PL 스펙트럼에서는 전도대아래 준 연속적으로 분포된 electron trap과 deep donor level, 그리고 가전자대 위 0.07 eV, 0.12 eV에 있는 acceptor level 사이의 전자전이에 의한 2개의 emission band를 2.13 eV와 1.20 eV 영역에서 관측하였으며, Ni-doped 단결정에서는 Ni^(2+) 이온의 여기상태 ³T₁ (³P)와 바닥상태 ³T₁ (³F) 사이의 전자전이에 의한 emission band를 1.48 eV 영역에서 관측하였다. 이러한 결과로부터 제안된 CdGa₂Se₄의 energy band model은 본 연구의 PL mechanism을 설명하는데 가능함을 보여주었다. PL and PLE spectra of Ni-doped and undoped CdGa₂Se₄ single crystals grown by the iodine transport technique have been investigated. In the PL spectra of undoped CdGa₂Se₄ two emission bands with the maxima at energies 2.13 and 1.20 eV are observed. The emission band at 2.13 eV is attributed to radiative transitions from quasi-continuously distributed traps below the bottom of the conduction band to an acceptor level at 0.07 eV above the valence band. Also, the emission band of 1.20 eV is assigned as DA (donor-accptor) pair recombination between a deep donor level and an acceptor level at 0.12 eV above the valence band. The emission band of 1.48 eV observed in Ni-doped CdGa₂Se₄ is due to intracenter transitions of Ni^(2+) ions from the excited state ³T₁ (³P) to the ground state ³T₁ (³F). The proposed energy band model permits is to explain the radiative recombinatiin processes in CdGa₂Se₄.
현승철,오석균,윤상현,김화택,김형곤,최성휴,김창대,윤창선,권숙일,Hyun, Seung-Cheol,Oh, Seok-Kyun,Yun, Sang-Hyun,Kim, Wha-Tek,Kim, Hyung-Gon,Choe, Sung-Hyu,Kim, Chang-Dae,Yoon, Chang-Sun,Kwun, Sook-Il 한국진공학회 1993 Applied Science and Convergence Technology Vol.2 No.2
$SbS_{1-x}Se_xI,\;BiS_{1-x}Se_xI,\;Sb_{1-x}Bi_xSI,\;Sb_{1-x}Bi_xSeI,\;SbS_{1-x}Se_xI:Co,\;BiS_{1-x}Se_xI:Co,\;Sb_{1-x}Bi_xSI:Co$, and $Sb_{1-x}Bi_xSeI:Co$ single crystals were grown by the vertical Bridgman method using the ingots. It has been found that these single crystals have an orthorhombic structure and indirect optical transition. The composition dependences of energy gaps are given by $E_g(x)=E_g(0)-Ax+Bx^2$. The impurity optical absorption peaks due to cobalt deped with impurity are attributed to the electron transitions between the split energy levels of $Co^{2+}$ and $Co^{3+}$ ions sited at $T_d$symmetry of the host lattice.