• Journal of Sensor Science and Technology
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• v.30 no.5
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• pp.279-285
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• 2021

Recently, cesium tellurium iodine (Cs₂TeI₆) has emerged as an inorganic halide perovskite material with potential application in optoelectronic devices due to its high absorption coefficient, suitable bandgap and because it consists of nontoxic and earth-abundant elements. However, studies on its fabrication process as well as photoresponse characteristics are limited. In this study, a simple and effective method is introduced for the synthesis of Cs₂TeI₆ thin films by a two-step dry process. A Cs₂TeI₆-based lateral photosensor was fabricated, and its photoresponse characteristics were explored under laser illuminations of four different wavelengths in the visible range: 405, 450, 520, and 655 nm. The initial photosensing results suggest potential application and can lead to more promising studies of Cs₂TeI₆ film in optoelectronics.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.1
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• pp.6-13
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• 2001

By using a vertical Bridgeman method, single crystalline structures of $Mg_xZn_{1-x}Te(0{\le}X{\le}0.48)$ were grown for various Mg mole compositions. With the increasing Mg fraction, the lattice constant is linearly increased from 6.103 to 6.239$\AA$ for the range of $0{\le}X{\le}0.48$ and the lattice constant of zincblende MgTe was linearly extrapolated to the value of 6.433$\pm$0.002$\AA$. The optical properties of the crystalline structure were characterized with photocurrent measurements. As a results of photocurrent spectra, the single crystalline $Mg_xZn_{1-x}Te$ show the energy bandgap of 2.380 and 2.260eV at 4.2 and 294 K, respectively. The photocurrent peak blueshifts with increasing Mg mole fraction and show the linear dependence of energy bandgap, $E_g$(X)=b+(0.8)X. The extrapolation shows the energy bandgaps of MgTe of 3.18 and 3.06eV at the temperatures of 4.2 and 294K, respectively. Furthermore, the photocurrent peaks redshifts with increasing temperature and the temperature coefficient is given to the value of $dE_g$/dT=-(5.6~$6.1){\times}10^{-4}$eV/K. for the temperature range above 100K.

• Journal of Bio-Environment Control
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• v.32 no.3
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• pp.242-248
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• 2023

This study was conducted to evaluate the effects of trinexapac-ethyl (TE) and prohexadione-calcium (PC) on the growth and turf quality of perennial ryegrass (Lolium perenne L.). Treatments were designed as follows; control (non-treatment), TE (TE 0.01 a.i. g·m^-2·100mL^-1), and PC (PC 0.01 a.i. g·m^-2·100mL^-1). Compared with control, turf color index and chlorophyll content of TE and PC treatments were not significantly different. As applied plant growth regulators (PGRs), shoot length in the TE and PC was decreased by 8.9-12.4% and 6.7-13.6%, respectively, and clipping yield by 44.4-45.8% and 40.6-40.9%. When evaluated with the growth of shoot length after applying PGRs, residual days of TE and PC were 43.6 and 37.9 days after treatment of PGRs (DAT) in the 1st experiment (July 29-August 26), respectively, and 38.3 and 39.5 DATs in the 2nd experiment (September 30-October 28). These results indicated that an application of TE or PC decreased shoot length and clipping yield in the perennial ryegrass, and their residual time was about 40±3 DATs. Perennial ryegrass applied with PGRs like TE and PC was not significant seasonal difference, and might be not phytotoxic.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.114-115
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• 2007

In this study, low temperature sintering property of the $0.6TiTe_3O_8-0.4MgTiO_3$ ceramics with sintering adds were investigated for LTCC application which enable to cofiring with Ag electrode. $TiTe_3O_8$ mixed with $MgTiO_3$ to improve the temperature property. In the X-ray diffraction patterns, the columbite structure of $TiTe_3O_3$ phase and ilmenite structure of $MgTiO_3$ phase were coexisted in all specimens. In the case of $H_3BO_3$ addition, the bulk density and dielectric constant were decreased but quality factor was increased with amount of $H_3BO_3$ additions. The TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3+xwt%H_3BO_3$ ceramics were moved to positive direction. In another case, SnO addition, the bulk density and dielectric constant were increased but Quality factor was decreased with amount of SnO additions. The TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3$+ywt%SnO ceramics were shifted to negative direction. The dielectric constant, quality factor and TCRF of the $0.6TiTe_3O_8-0.4MgTiO_3$ ceramics with $2wt%H_3BO_3$ and 2.5wt%SnO sintered at $830^{\circ}C$ for 1h, were 28.5, 39,570GHz, $+9.34ppm/^{\circ}C$ and 29.86, 35,80000z, $-0.58ppm/^{\circ}C$, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.440-448
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• 2004

In this paper, to make a solar cell of II-Ⅵ ZnTe compound semiconductor, we studied for the property of the transparent electrode(AZO) and Buffer layer(ZnO), and for reducing the energyband gap of optical absorber layer which are most effective on its efficiency. The ZnTe thin film was used the optical absorber layer of solar cell. Zn and Te were deposited using the co-sputtering method. The thin film was sputtered RF power of Zn/50W and Te/30W, respectively and a substrate temperature of foot under Ar atmosphere of 10mTorr. The energy band gap of the thin film was 1.73ev Then the thin film was annealed at $400^{\circ}C$ for 10sec under a vacuum atmosphere. The energy band gap of 1.67eV was achieved and the film composition ratio of Zn and Te was 32% and 68%. At the best condition, the Solar Cell was manufactured and the efficiency of 6.85% (Voc: 0.69V, Jsc: 21.408㎃/$cm^2$, Fill factor (FF): 0.46) was achieved.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.298-299
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• 2012

현재 반도체 나노구조는 단전자 트랜지스터, 레이저, LED, 적외선 검출기 등과 같은 고효율 광전자 소자에서의 응용을 위해 활발한 연구가 진행 되고 있다. 이러한 응용 분야를 위한 다양한 종류의 나노구조 성장이 광범위하게 시도 되고 있지만 주로 III-V 족 화합물 반도체에 대한 연구가 주를 이룬 반면 II-VI 족 화합물 반도체에 대한 연구는 아직 미흡하다. 하지만 II-VI 족 화합물 반도체는 III-V 족 화합물 반도체와 비교했을 때 더 큰 엑시톤 결합에너지(exciton binding energy)를 가지는 우수한 특성을 보이고 있으며 이러한 성질을 가지는 II-VI 족 화합물 반도체 중에서도 넓은 에너지 갭을 가지는 CdTe 양자점은 녹색 영역대의 광전자 소자로서 활용되고 있다. 본 연구에서는 분자 선속 에피 성장법(molecular beam epitaxy; MBE)과 원자 층 교대 성장법(atomic layer epitaxy; ALE)으로 CdTe 두께에 따른CdTe/ZnTe 나노구조의 광학적 특성을 연구하였다. 광루미네센스(photoluminescence; PL)를 통해 CdTe/ZnTe 나노구조에서 CdTe 두께에 따른 에너지 밴드와 열적 활성화 에너지를 관찰하였다. 또한 시분해 광루미네센스(Time-resolved PL)를 통해 CdTe 두께에 따른 CdTe/ZnTe 나노구조의 운반자 동역학을 조사하였다. 저온 광루미네센스 측정 결과 CdTe 두께가 증가할수록 각 샘플의 피크는 더 낮은 에너지 영역대로 이동하는 것을 관찰할 수 있다. 1.2 에서 2.0 ML로 증가할 때 광 루미네센스의 작은 적색편이를 관찰할 수 있는데, 이는 CdTe 양자우물에서 양자점으로의 구조적인 전이가 일어남에 따라 구속효과가 증가하였기 때문이다. 또한 2.0 에서 3.6 ML까지 CdTe 두께가 증가할 때 측정된 적색편이 현상은 양자점의 사이즈 증가함에 따른 것이다. 마지막으로 3.6 에서 4.4 ML로 CdTe 두께가 증가할 때 큰 적색편이 현상을 볼 수 있는데 이는 CdTe 양자점에서 양자세선으로의 구조적 전이에 따라 구속효과가 증가하였기 때문이다. 온도 의존 광루미네센스(Temperature-dependent PL) 측정 결과 1.2 와 3.0 ML 두께의 CdTe/ZnTe 나노구조에서 구속된 전자의 열적 활성화 에너지가 18 과 35 meV로 관찰되었다. 3.0 ML CdTe/ZnTe 나노구조에서 가장 큰 열적 활성화 에너지를 갖는 것은 양자점의 균일도가 좋아지고 저차원 나노구조로의 구조적 전이가 일어나면서 운반자 구속효과에 다른 쿨롱 상호작용이 증가하였기 때문이다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.297.1-297.1
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• 2014

칼코겐화합물은 주기율표 6족에서 산소를 제외한 칼코겐 원소가 하나 이상 포함되는 화합물 반도체 소재로 상변화 및 광전변환 특성을 가지고 있다. 이와 같은 칼코겐화합물의 장점을 이용하여 집적회로의 로직 블록 간의 신호 전달을 제어하는 프로그래머블 스위치를 구현 할 수 있다. 본 연구에서는 프로그래머블 스위치에 적용 가능한 칼코겐화합물로 널리 알려진 GeSbTe 및 GeTe 박막의 도핑에 따른 전기적, 구조적 특성 변화를 보고한다. RF magnetron sputtering 방식을 이용하여 doped GST 및 doped GeTe 박막을 증착하고 도핑에 따른 전기적, 구조적 특성을 관찰하였다. GST 박막의 경우 도핑에 의해 면저항 값이 증가하고 결정화 온도가 상승하는 것을 확인하였다. 반면 GeTe 박막에서는 도핑에 의해 면저항 값이 감소하고 결정화 온도가 낮아지는 것을 확인하였다. 이러한 결과로부터 GeSbTe 및 GeTe 박막의 전기적 특성은 도핑에 따라 변화하며, 도핑 조건을 적절히 조절함으로써 프로그래머블 스위치에 적용 가능한 칼코겐화합물의 확보가 가능하다는 결론을 내릴 수 있다.

• Journal of Powder Materials
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• v.7 no.1
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• pp.6-11
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• 2000

Two kinds of Bi2Te3 powders, pure Bi2Te3/2vol.%ZrO2, have been prepared by a mechanical grinding process process. Effect of mixing of the powders on thermoelectric of the sintered body has been investigated by measuring Seebeck Coeffcient, specific electric resistivity and thermal conductivity. With an increase in the weight fraction of the Bi2Te3/2vol.%ZrO2 powder from 0 to 40wt.%. Especially, the figure of merit of the mixedBi2Te3 sintered body increases and thereafter dedreases above 40wt.%. Especially. the figure of merit of the mixed Bi2Te3 sintered bodies with mixing of Bi2Te3/2vol.%ZrO2 powder increased about 1.3time in comparison with the value of the specimen before mixing. Mixing of two kinds of Bi2Te3 powders which have different theramal and electric propertries with each other seemed to be useful methob to increase the figure of merit of Bi2Te3 sintered body.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1082-1085
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• 2012

CdTe nanoribbons feature their unique optical properties compared with CdTe nanoparticles. Slow oxidation of tellurium ions on CdTe nanoparticles resulted in the organization of individual nanoparticle into nanoribbons. The light-controlled self-assembly of CdTe nanoparticles led to twisted ribbons. It was found that irradiation improved the oxidation of tellurium ions. Transmission electron microscopy (TEM) were performed to characterize the synthesized nanostructures and showed nanowires were twisted after self-assembly. The photoluminescence was slightly blue-shifted from 550 to 544 nm. This synthetic procedure could potentially provide a key step toward the fabrication of nanowires.

• Journal of Sensor Science and Technology
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• v.15 no.6
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• pp.379-385
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• 2006

Single crystal of p-$CdIn_{2}Te_{4}$ was grown in a three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by x-ray diffraction and photoluminescence measurements. From the photoluminescence spectra of the as-grown $CdIn_{2}Te_{4}$ crystal and the various heat-treated crystals, the ($D^{o}$, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the $CdIn_{2}Te_{4}$:Cd, while the ($A^{o}$, X) emission completely disappeared in the $CdIn_{2}Te_{4}$:Cd. However, the ($A^{o}$, X) emission in the photoluminescence spectrum of the $CdIn_{2}Te_{4}$:Te was the dominant intensity like in the as-grown $CdIn_{2}Te_{4}$ crystal. These results indicated that the ($D^{o}$, X) is associated with $V_{Te}$ which acted as donor and that the ($A^{o}$, X) emission is related to $V_{Cd}$ which acted as acceptor, respectively. The p-$CdIn_{2}Te_{4}$ crystal was obviously found to be converted into n-type after annealing in Cd atmosphere. The origin of ($D^{o},{\;}A^{o}$) emission and its to phonon replicas is related to the interaction between donors such as $V_{Te}$ or $Cd_{int}$, and acceptors such as $V_{Cd}$ or $Te_{int}$. Also, the In in the $CdIn_{2}Te_{4}$ was confirmed not to form the native defects because it existed in a stable bonding form.