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.

Ga₂S₃: Er 단결정의 Photoluminescence 특성 연구

진문석(Moon-Seog Jin),김화택(Wha-Tek Kim) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.1

두가지 종류의 Ga₂S₃:Er(A형 및 B형) 단결정을 iodine을 수송매체로 사용하는 화학수송법으로 성장시켰다. 성장된 단결정은 모두 단사정계 결정구조를 갖고 있었다. 광흡수 측정으로부터 구한 광학적 에너지 띠 간격은 13 K에서 A형 단결정이 3.375±0.001 eV, B형 단결정이 3.365±0.001 eV로 주어졌다. 이들 Ga₂S₃:Er 단결정을 Cd-He 레이저의 325 ㎚-선으로 여기하여 측정한 photoluminescence 스펙트럼에서, A형 단결정은 444 ㎚에 피크가 위치하는 강한 청색발광띠가 나타났으며 518 ㎚과 690 ㎚에 피크가 위치하는 녹색발광띠 및 적색발광띠가 나타났다. B형 단결정은 513 ㎚과 695 ㎚에 피크가 위치하는 녹색발광띠 및 적색발광띠만이 나타났다. 두가지 종류의 단결정 모두에서 525 ㎚, 553 ㎚, 664 ㎚, 812 ㎚, 986 ㎚, 1540 ㎚ 파장 영역 부근에 위치하는 예리한 발광피크들이 나타났으며, 이들 예리한 발광피크는 Er^(3+) 이온의 에너지 준위 사이의 전자전이에 의하여 나타나는 것으로 해석된다. Two kinds of Ga₂S₃:Er (type A and type B) single crystals were grown by the chemical transport reaction method using iodine as a transport agent. The single crystals were crystallized into a monoclinic structure. The optical energy band gaps were found to be 3.375 eV for the Ga₂S₃:Er (type A) single crystal and 3.365 eV for the Ga₂S₃:Er (type B) single crystal at 13 K. When the Ga₂S₃:Er (type A and type B) single crystals were excited by the 325 ㎚-line of a Cd-He laser, photoluminescence spectra of the Ga₂S₃:Er (type A) single crystal exhibited blue emission band peaked at 444 ㎚ and green and red emission bands peaked at 518 ㎚ and 690 ㎚. Photoluminescence spectra of the Ga₂S₃:Er (type B) single crystal showed green and red emission bands peaked at 513 ㎚ and 695 ㎚. Sharp emission peaks in the two kinds of Ga₂S₃:Er single crystals were observed near 525 ㎚, 553 ㎚, 664 ㎚, 812 ㎚, 986 ㎚, and 1540 ㎚ and analysed as originating from the electron transitions between the energy levels of Er^(3+) ion.

CuAl₁_xGa xSe₂ 및 CuAl₁_xGa xSe₂ : CO²+ 단결정의 광학적 특성

진문석(Moon-Seog Jin),김화택(Wha-Tek Kim) 한국진공학회(ASCT) 1994 Applied Science and Convergence Technology Vol.3 No.3

삼원화합물 반도체, CuAlSe₂ 및 CuGaSe₂ 단결정의 solid solution인 CuAl_(1-x)Ga_xSe₂ 및 cobalt를 2.0 mol% 첨가한 CuAl(1-x)Ga_xSe₂:Co^(2+) 단결정을 iodine을 수송물질로 사용한 화학수송법으로 성장시켰다. source material로는 CuAl_(1-x)Ga_xSe₂의 화학조성비에서 Se를 3.0mol% 과잉으로 첨가하여 합성한 ingot를 사용하였으며, 불순물이 첨가된 CuAl_(1-x)Ga_xSe₂:Co^(2+) 단결정 성장시에는 source material 에 cobalt 분말을 2.0mol% 첨가하였다. X-선 회절무늬로부터 성장된 단결정들이 chalcopyrite 결정구조를 하고 있음을 확인하였으며 격자상수를 구하였다. 광흡수 spectra 측정으로부터 성장된 단결정의 optical energy gap 조성의존성을 규명하였고, 결정장 이론을 적용하여 CuAl_(1-x)Ga_xSe₂:Co^(2+) 단결정에서 나타나는 cobalt 불순물에 의한 광흡수 peak가 T_d 대칭점에 위치한 Co^(+2) 이온의 에너지 준위들간 전자전이에 의해 나타남을 규명하였다. The solid solution, CuAl_(1-x)Ga_xSe₂ single crystals of ternary compound semiconductors, CuAlSe₂ and CuGaSe₂, and CuAl(1-x)Ga_xSe₂:Co^(2+) single crystals doped with 2.0 mol% of cobalt as an impurity were grown by the chemical transport reaction method using iodine as the transport agency. Then, CuAl_(1-x)Ga_xSe₂ ingot synthesized from stoichiometric eleemnts, Cu, AI, Ga and Se with excess Se of 3.0 mol% was used as a source material. To grow CuAl_(1-x)Ga_xSe₂:Co^(2+) single crystal, cobalt powder of 2.0 mol% was added to the source matera1. The grown single crystals were crystalized in the chalcopyrite structure and lattice constants were obtained from X-ray diffraction. From the analysis of optical absorption spectra, the composition dependence of the optical energy gap was decided. Applying the crystal field theory to impurity optical absorption peaks in CuAl_(1-x)Ga_xSe₂:Co^(2+) single crystals, it was identified that the impurity optical absorption are originated in the electron transition between the energy levels of Co^(2+) ion sited at T_d symmetry point in the host crystals.

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.

Aluminum을 포함한 삼원화합물 반도체의 합성 및 단결정 성장과 광학적 특성 규명에 관한 연구 Ⅱ -ZnAl₂S₄, ZnAl₂Se₄, CdAl₂S₄, CdAl₂Se₄를 중심으로 -

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.