• Bulletin of the Korean Chemical Society
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• v.21 no.8
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• pp.769-773
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• 2000

The dependence of photoluminescence (PL) and photoluminescence itation (PLE) on preparation condi-tions and the aging of porous silicon carbide (PSC) have been investigatted. The fiber size of the material pre-pared under dark-current mode, labele d DCM, was larger than that of the photoassisted (PA)process.The intensity of the PL spectrum for the PA condition was higher than that of the DCM condition. The PA condition giving small fiber size exhibited amore prominent high-energy component but the emission bands of both con-ditionsobserved were rather similar. The origin of the PL may have played an importantrole in the surface defect center introduced by the reaction conditions ofHFatthe surface of the silicon carbide. Selective excita-tion of the PL bandsusingdifferent excitation wavelengths has been used to identify distinct componentswith-in the PL bandwidth. Two main PL bands with peak wavelength of494 and534 nm were clearly resolved. On the other hand, selectivc emission of the PLEbands using different emission wavelengths has been used to identify distinct components within the PLE bandwidth. The higher energy band with peak wavelength of 338 nm and the lower energy bands involving 390,451 and 500 nm were clearly resolved. According to the pro-ionged aging in air, PL spectra appearedasone band, This emission probably originated from states localized to the band-to-band recombination due to the oxidation on the crystallite surface.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.195-199
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• 2003

The $p-CdIn_2$$Te_4$single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. From the photoluminescence spectra of the as-grown $CdIn_2$$Te_4$crystal and the various heat-treated crystals, the ($D^{\circ}$, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the $CdIn_2$T $e_4$:Cd, while the ($A^{\circ}$, X) emission completely disappeared in the $CdIn_2$T $e_4$:Cd. However, the ($A^{\circ}$, X) emission in the photoluminescence spectrum of the $CdIn_2$T $e_4$:Te was the dominant intensity like an as-grown $CdIn_2$T $e_4$crystal. These results indicated that the ($D^{\circ}$, X) is associated with $V_{Te}$ acted as donor and that the ($A^{\circ}$, X) emission is related to $V_{cd}$ acted as acceptor, respectively. The $p-CdIn_2$T $e_4$crystal was found to be obviously converted into the n-type after annealing in the Cd atmosphere. The origin of ( $D^{\circ}$, $A^{\circ}$) emission and its TO phonon replicas is related to the interaction between donors such as $V_{Te}$ or $Cd_{int}$, and accepters such as $V_{cd}$ or T $e_{int}$. Also, the In in the $CdIn_2$X$CdIn_4$was confirmed not to form the native defects because it existed in the stable form of bonds.

• Journal of the Korean Vacuum Society
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• v.22 no.6
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• pp.291-297
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• 2013

ZnO nanowires were synthesized by vapor-liquid-solid (VLS) process using ZnO and graphite powders on the sapphire substrate coated with an Au film as a catalyst. ZnO nanowires had two prominent emission bands; i) near-band edge (NBE) emission band at 380 nm, and ii) a relatively stronger deep level (DL) emission band ($I_{NBE}/I_{DL}$ <1). In order for the ZnO nanowires to be utilized as an effective material for UV emitting devices, the photoluminescence intensity of NBE needs to be improved with the decreased intensity of DL. In the current study, hydrogen plasma treatment was performed to improve the photoluminescence characteristics of ZnO nanowires. With the hydrogen plasma treatment time of more than 120 sec, the extent of performance improvement was gradually decreased. However, the intensity ratio of NBE to DL ($I_{NBE}/I_{DL}$) was significantly improved to about 4 with a relatively short plasma treatment time of 90 sec, suggesting hydrogen plasma treatment is a promising approach to improve the photoluminescence properties of ZnO nanowires.

• Korean Journal of Materials Research
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• v.22 no.3
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• pp.140-144
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• 2012

Compared with bulk material, quantum dots have received increasing attention due to their fascinating physical properties, including optical and electronic properties, which are due to the quantum confinement effect. Especially, Luminescent CdSe quantum dots have been highly investigated due to their tunable size-dependent photoluminescence across the visible spectrum. They are of great interest for technical applications such as light-emitting devices, lasers, and fluorescent labels. In particular, quantum dot-based light-emitting diodes emit high luminance. Quantum dots have very high luminescence properties because of their absorption coefficient and quantum efficiency, which are higher than those of typical dyes. CdSe quantum dots were synthesized as a function of the synthesis time and synthesis temperature. The photoluminescence properties were found strongly to depend on the reaction time and the temperature due to the core size changing. It was also observed that the photoluminescence intensity is decreased with the synthesis time due to the temperature dependence of the band gap. The wavelength of the synthesized quantum dots was about 550-700 nm and the intensity of the photoluminescence increased about 22~70%. After the CdSe quantum dots were synthesized, the particles were found to have grown until reaching a saturated concentration as time increased. Red shift occurred because of the particle growth. The microstructure and phase developments were measured by transmission electron microscopy (TEM) and X-ray diffractometry (XRD), respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.179-182
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• 2004

The $p-CdIn_2Te_4$ single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. From the Photoluminescence spectra of the as-grown $CdIn_2Te_4$ 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 $CdIn_2Te_4:Cd$, while the $(A^{o},X)$ emission completely disappeared in the $CdIn_2Te_4:Cd$. However, the $(A^{o},X)$ emission in the photoluminescence spectrum of the $CdIn_2Te_4:Te$ was the dominant intensity like an as-grown $p-CdIn_2Te_4$ crystal. These results indicated that the $(D^{o},X)$ is associated with $V_{Te}$ acted as donor and that the $(A^{o},X)$ emission is related to $V_{Cd}$ acted as acceptor, respectively. The $p-CdIn_2Te_4$ crystal was found to be obviously converted into the n-type after annealing in the 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 accepters such as $V_{Cd}$ or $Te_{int}$. Also, the In in the $CdIn_2Te_4$ was confirmed not to form the native defects because it existed in the stable form of bonds.

• Journal of the Korean Electrochemical Society
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• v.4 no.1
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• pp.10-13
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• 2001

Effects of an anionic surfactant pentadecafluorooctanoic acid on the photoluminescence of porous silicon was investigated, which was prepared by photoelectrochemical etching at 4V of single crystalline n-type silicon (100) with the specific resistivity of $0.4\~0.8{\Omega}{\cdot}cm$. Photoluminescence shifted to shorter wavelength and its intensity decreased when the concentration of the surfactant increased. FT-IR and contact angle data supported the presence of the surfactant lying on the surface of porous silicon.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.278-281
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• 2003

The p-CIn2Te4 single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. From the photoluminescence spectra of the as-grown CdIn2Te4 crystal and the various heat-treated crystals, the (Do, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the CdIn2Te4:Cd, while the (Ao, X) emission completely disappeared in the CdIn2Te4:Cd. However, the (Ao, X) emission in the photoluminescence spectrum of the CdIn2Te4:Te was the dominant intensity like an as-grown CdIn2Te4 crystal. These results indicated that the (Do, X) is associated with VTe acted as donor and that the (Ao, X) emission is related to VCd acted as acceptor, respectively. The p-CdIn2Te4 crystal was found to be obviously converted into the n-type after annealing in the Cd atmosphere. The origin of (Do, Ao) emission and its TO phonon replicas is related to the interaction between donors such as VTe or Cdint, and accepters such as VCd or Teint. Also, the In in the CdIn2Te4 was confirmed not to form the native defects because it existed in the stable form of bonds.

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.183-190
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• 2002

Photoluminescence(PL) properties of $Si^+$-implanted $SiO_2$ film, which was thermally grown on c-Si substrate, is reported. We have compared room temperature photoluminescence (PL) spectra of the samples which was made in several kinds of implantation, subsequent annealing and $SiO_2$ film thickness. XRD data was correlated with the PL spectra. Silicon nanocrystals in $SiO_2$ film is considered as the origin of the photoluminescence. PL spectra was investigated after wet etching of the $SiO_2$ film by using BOE (Buffered Oxide Etchant) at every one minute. PL peak wavelength was varied as the etching is proceeded. These results indicate that the quantity and the distribution of dominant size of Si nanocrystals in $SiO_2$ film seem to have a direct effect on PL spectrum.

• 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.

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.1-5
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• 2007

The 1R(Infra-Red) spectrum and PL(Photoluminescence) of the antiferromagnetic pure $MnF_2$ and the single crystal $MnF_2(1.5%\;EuF_3)$ with the rutile structures were measured. The detailed analysis of the measured PL data showed the differences of the optical property between the single crystal $MnF_2(1.5%\;EuF_3)$ and the pure $MnF_2$. It was found that the additional PL peak by the doping of the $EuF_3$ in $MnF_2$ is originated from the f-d transition of $Eu^{3+}$ from the temperature dependent intensity measurement.