• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.2
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• pp.84-88
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• 2021

The change of the photoluminescence properties of La2O3-CaF2-Al2O3-SiO2 glass-ceramics doped with rare earth material, that is used as laser and optical sensors, was analyzed according to heat treatment temperature. The heat treatment conditions for fabricating glass-ceramics were obtained through non-isothermal thermal analysis, and X-ray diffraction analysis was performed to determine the degree of crystal growth and kinds of crystal phases generated according to the heat treatment temperature. Using Scherrer's equation, it was predicted that crystals with a size of 25~40 nm would be generated inside the glass-ceramics. Photoluminescence (PL) analysis showed that the specimens heat-treated at 660℃ to 670℃ for 1 hour had the highest PL intensity. Also, from the CIE color coordinate analysis, all glass-ceramics specimens emitted red-orange light regardless of the heat treatment condition.

• Transactions on Electrical and Electronic Materials
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• v.11 no.4
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• pp.170-173
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• 2010

Nanocrystalline cadmium sulfide (CdS) thin films were prepared using chemical bath deposition in a solution bath containing $CdSO_4$, $SC(NH_2)_2$, and $NH_4OH$. The CdS thin films were investigated using X-ray diffraction (XRD), photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). The as-deposited CdS thin film prepared at $80^{\circ}C$ for 60 min had a cubic phase with homogeneous and small grains. In the PL spectrum of the 2,900 A-thick CdS thin film, the broad red band around 1.7 eV and the broad high-energy band around 2.7 eV are attributed to the S vacancy and the band-to-band transition, respectively. As the deposition time increases to over 90 min, the PL intensity from the band-to-band transition significantly increases. The temperature dependence of the PL intensity for the CdS thin films was studied from 16 to 300 K. The $E_A$ and $E_B$ activation energies are obtained by fitting the temperature dependence of the PL intensity. The $E_A$ and $E_B$ are caused by the deep trap and shallow surface traps, respectively. From the FTIR analysis of the CdS thin films, a broad absorption band of the OH stretching vibration in the range $3,000-3,600\;cm^{-1}$ and the peak of the CN stretching vibration at $2,000\;cm^{-1}$ were found.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1033-1036
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• 2004

Si nanocrystallites thin films on p-type (100) Si substrate have been fabricated by pulsed laser deposition using a Nd:YAG laser. After deposition, samples were annealed at the temperatures of 400 to $800^{\circ}C$. Hydrogen passivation was then performed in the forming gas (95% $N_2$ + 5% $H_2$) for 1 hr. Strong violet-indigo photoluminescence has been observed at room temperature from nitrogen ambient-annealed Si nanocrystallites. The variation of photoluminescence (PL) Properties of Si nanocrystallites thin films has been investigated depending on annealing temperatures with hydrogen passivation. From the results of PL, Fourier transform infrared (FTIR), and high-resolution transmission electron microscopy (HRTEM) measurements, it is observed that the origin of violet-indigo PL from the nanocrystalline silicon in the silicon oxide film is related to the quantum size effect of Si nanocrystallites and oxygen vacancies in the SiOx(x : 1.6-1.8) matrix affects the emission intensity.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.413-417
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• 2014

The effect of calcination treatment of raw powders prior to high temperature synthesis of Ca-${\alpha}$-SiAlON:$Eu^{2+}$ phosphor was investigated. Based on data acquired from thermogravimetric analysis, calcination temperatures were set at 600, 750, and $900^{\circ}C$. Compared to the photoluminescence (PL) intensity of direct synthesis without calcination, a similar intensity was found for the $600^{\circ}C$ treatment, a 19% increased PL intensity was found for the $750^{\circ}C$ treatment, and a 23% decreased PL intensity was found for the $900^{\circ}C$ treatment. Observation of the particle morphology of the synthesized phosphors revealed that the material transport promoted through the agglomerates formed by the $750^{\circ}C$ treatment led to enhanced PL intensity. On the other hand, the oxidation of the starting AlN particles during the $900^{\circ}C$ treatment resulted in decreased photoluminescence.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.6
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• pp.279-283
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• 2003

In this study, ZnTe : S single crystal thin films substituted by sulfur were grown on GaAs (100) substrates by hot-wall epitaxy. The photoluminescence (PL) characteristics of ZnTe : S single crystal thin films was measured to investigate the effects due to sulfur atoms in the ZnTe layer. The Peak of 2.339 eV identified as the isoelectronic center was observed in low temperature PL spectrum, but PL spectra which the origin had not been well-explained were not observed. Temperature dependence of PL intensities of the light hole free exciton was explained by extrinsic self-trapping. Besides it is reported that the emission lines near absorption edge at room temperature were observed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.10-16
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• 2010

In this paper, synthesis here Mn add to Ar injection the state and a vacuum an atomosphere $ZnGa_2O_4$ : Mn, ZnO and $Ga_2O_3$ power of 1 : 1 mole ratio mixture. Manufacture a close examination of oxygen a component variation luminescence a specific character reach an in fluence of $ZnGa_2O_4$ : Mn, luminescence spectrum observation also an explanation of Mn site symmetry and at luminescence spectrum reach an influence from low temperature photoluminescence spectrum.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.859-862
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• 2008

We have realized static image on organic light emitting diodes (OLEDs) using photoluminescence degradation. Ultraviolet (UV) was irradiated to the glass side of device. UV power was 350 Wand the wavelength was 365 nm. The UV irradiation gives rise to the degradation of photoluminescence. Due to the degradation, the current density-voltage curve was shifted to the higher voltage side and the luminescence was also degraded by the current and photoluminescence drop. The negative imaged films were prepared to control the transmittance of UV. The UV light was passed through the film. By this method, the film image was transferred to the device with reversed image and the static image was realized on the OLED.

• Journal of Integrative Natural Science
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• v.14 no.4
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• pp.147-154
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• 2021

A luminescent porous silicon sensor, whose surface was passivated with organic molecule via hydrosilylation under various conditions, has been researched to measure the photoluminescence (PL) stability of porous silicon (PSi). Photoluminescent PSi were synthesized by an electrochemical etching of n-type silicon wafer under the illumination with a 300 W tungsten filament bulb during the etching process. The PL of PSi displayed at 650 nm, which is due to the quantum confinement of silicon quantum dots in the PSi. To stabilized the photoluminescence of PSi, the hydrosilylation of PSi with silole molecule containg vinyl group was performed. Surface morphologies of fresh PSi and surface-modified PSi were obtained with a cold FE-SEM. Optical characterization of red photoluminescent silicon quantum dots was investigated by UV-vis and fluorescence spectrometer.

• Journal of the Korean Chemical Society
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• v.60 no.2
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• pp.131-136
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• 2016

Copper ion induced photoluminescence (PL) quenching dynamics and recovery of the PL by zinc ions were investigated for CdSe based nanocrystals. When copper ions were added, CdSe quantum dots showed fast and dramatically PL quenching whereas PL of CdSe nanorod gradually decreased. In the presence of zinc ions, the PL of CdSe/CdS (core/shell) nanocrystals that have quenched by copper ions was efficiently recovered. It showed that the PL intensity of nanocrystals increased by 50% in a solution containing 1 μM zinc ions. The PL intensity was increasing with increasing zinc ions, and could be described by Langmuir binding isotherm model. We showcase that the CdSe based nanocrystals can be used as fluorescence turn-on sensor.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.379-384
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• 1994

Room-temperature photoluminescent porous Si has been formed by etching Si wafer u-ith the solution of $HF:HNO_{3}: H_{2}O$=l : 5 : 10. We have observed photoluminescence(PL) spectra similar to those reported recently for porous-Si films formed by anodic etching with HF solutions. We have also investigated the dependence of PI, spectra on the etching time which was varied from 1 to 10 minutes. We found that 5-minute etching gave us the strongest PL intensity. We also found by atomic force microscopy( AFM) measurements that the surface fearure size became smaller for longer etching time and the average feature size of the etched Si wafer for 5-minute was about 1, 500~2, 000$\AA$. This indicates that the surface feature of the etched porous Si affects the PL intensity of the sample.