• Journal of Advanced Marine Engineering and Technology
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• v.30 no.1
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• pp.176-181
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• 2006

In this study, systematical investigations were carried out on crystal qualifies and optical properties of $ZnSe_{1-x}:Te_x$ (x=0.002-0.04) thin films frown by molecular beam epitaxy (MBE). The crystal qualifies and optical properties have been investigated by X-ray diffraction (XRD) and Photoluminescence (PL) measurements, respectively. From the XRD measurements, the crystallographic characteristics showed mediocre crystal quality with increasing the Te composition. From the PL measurements, emission in the visible spectrum region from blue to green was obtained by varying the Te content of the ZnSe:Te epilayers. The efficient blue and green emission were attributed to the recombination of excitons trapped at isoelectronic isolated a single Te atom and $Te_n(n{\geq}2)$ clusters. respectively. The blue emission become dominant in Te tightly doped $ZnSe_{1-x}:Te_x$ $(Te=0.2\%)$ epilayers with increasing temperature. For the Te heavily doping condition $(Te=4.0\%)$, the dominant green emission could be observed at around 160K.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1032-1037
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• 2003

Boron-doped CdS thin films were chemically deposited onto glass substrates. X-ray diffraction (XRD), photoluminescence (PL), and Raman techniques were used to evaluate the quality of B-doped CdS films. XRD results have confirmed that B-doped CdS films has a hexagonal structure with a preferential orientation of the (002) plane. The PL spectra for all samples consists of two prominent broad bands around 2.3 eV (green emission) and 1.6 eV (red emission) and the higher doping concentrations gradually decreased the green emission and red emission. Raman analysis has shown that undoped films have structure superior to those of B-doped CdS films. Boron doping into CdS films improved the optical transmittance and increased the optical band gap.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.4
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• pp.395-401
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• 2013

In-situ optical emission spectroscopy (OES) is employed for leak detection in plasma etching system. A misprocessing is reported for significantly reduced silicon etch rate with chlorine gas, and OES is used as a supplementary sensor to analyze the gas phase species that reside in the process chamber. Potential cause of misprocessing reaches to chamber O-ring wear out, MFC leaks, and/or leak at gas delivery line, and experiments are performed to funnel down the potential of the cause. While monitoring the plasma chemistry of the process chamber using OES, the emission trace for nitrogen species is observed at the chlorine gas supply. No trace of nitrogen species is found in other than chlorine gas supply, and we found that the amount of chlorine gas is slightly fluctuating. We successfully found the root cause of the reported misprocessing which may jeopardize the quality of thin film processing. Based on a quantitative analysis of the amount of nitrogen observed in the chamber, we conclude that the source of the leak is the fitting of the chlorine mass flow controller with the amount of around 2-5 sccm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.103-112
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• 2011

This paper is tried to analysis the optical emission spectroscopy related to the position of inductive load coil and flow rates of methane and oxygen in the RF inductive plasma process. According to the position of load coil, peak of $H_{\alpha}$, $H_{\beta}$, and CH were appeared strongly at the middle position of the coil and it decreased both direction. The electron temperature was approximately 0.9[eV] at that position. Emission intensities of $H_{\alpha}$, $H_{\beta}$, and CH increased linearly by increasing input power. In addition, intensities of $H_{\alpha}$ and $H_{\beta}$ increased by increasing the flow rate of oxygen. It might be ascribed that the oxygen species were bonded with $C_nH_m$ by suppressing the combination with hydrogen atoms. Consequently, the optimal position of the inductive coil is decided to the intermediate position between 4th and 5th turns, the wanted carbon thin-film is possible to deposit by controlling flow rates of methane and oxygen.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.13-18
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• 2008

We numerically investigate by the finite-difference time-domain method the effects of surface termination on directional emission exiting a photonic crystal waveguide. The directed power and far-field beam profile for the original proposal [E. Moreno et al., Phys. Rev. B 69, 121402 (2004)] and its enhancement [S. K. Morrison et al., Appl. Phys. Lett. 86, 081110 (2005)] are computed for different values of some important parameters. We find another surface termination condition with a positive surface displacement in the structure of the original proposal which has a negative surface displacement. Our surface termination is more effective than the original structure, and nearly as effective as the termination for the enhancement, for directional emission. Besides, our termination is simpler than that for the enhancement. We confirm the effectiveness of directional emission from our termination in its far-field beam profile, radiation intensity distribution, and additionally the wave-vector space representation by the Fourier analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.50-53
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• 1994

In this study. we report the properties of optically pumped stimulated emission at room temperature (RT) from column-III nitride semiconductors of GaN, GaInN, AlGaN/GaN double hetero-structure (DH) and AlGaN/GaInN DH which grown by low pressure metal-organic vapor phase epitaxy on sapphire substrate using an AIN buffer-layer. The peak wavelength of the stimulated emission at RT from AlGaN/GaN DH is 370nm and the threshold of excitation pumping power density (P$\_$th/) is about 89㎾/$\textrm{cm}^2$, and they from AlGaN/GaInN DH are 403nm and 130㎾/$\textrm{cm}^2$, respectively. The P$\_$th/ of AlGaN/GaN and AlGaN/GaInN DHs are lower than the bulk materials due to optical confinement within the active layers of GaN and GaInN. The optical gain and the polarization of stimulated emission characteristics are presented in this article.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.245-246
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• 2011

Emission lines ratios were used for diagnostics of and excited level densities in low-temperature plasmas. In this work, an optical emission spectroscopy (OES) was used to determine the electron temperature and metastable level densities in low-pressure inductively coupled plasma. The emission spectroscopy method was based on a simple collisional-radiative model. The selected lines of the Ar(4p to 4s) were influenced by the radiation trapping at relatively high pressures where the plasma become optically thick. To quantify this effect, a pressure dependence factor ${\alpha}$(P) was derived by using corrections for the measured intensities. It was found that the lower metastable level densities were obtained when ${\alpha}$(P) increased with the increasing discharge pressure. The effect of non-Maxwellian electron energy distribution functions (EEDFs) on the metastables was also presented and discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.784-789
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• 1998

In this work, the optical properties of freestanding GaN single crystalline substrate grown by hydride vapor phase epitaxy(HVPE) were investigated. The low temperature PL spectrum in freestanding GaN consists of free and bound exciton emissions, and a deep DAP recombination around at 1.8eV. The optically-pumped stimulated emission in freestanding GaN substrate was observed at room temperature. At the maximum power density of 2MW/$\textrm{cm}^2$, the peak energy and FEHM of stimulated emission were 3.318 eV and 8meV, respectively. The excitation power dependence on the integrated emission intensity indicates the threshold pumping power density of 0.4 MW/$\textrm{cm}^2$.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.582-588
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• 2014

We study polarization-dependent spontaneous emission (SE) rate and light extraction efficiency (LEE) in localized-surface-plasmon (LSP)-coupled light emitting diodes (LEDs). The closely packed seven $Ag/SiO_2$ core-shell (CS) nanoparticles (NPs) lie on top of the GaN surface for LSP coupling with a radiated dipole. According to the dipole direction, both the SE rate and the LEE are significantly modified by the LSP effect at the $Ag/SiO_2$ CS NPs when the size of Ag, the thickness of $SiO_2$, and the position of the dipole source are varied. The enhancement of the SE rate is related to an induced dipole effect at the Ag, and the high LEE is caused by light scattering with an LSP mode at $Ag/SiO_2$ CS NPs. We suggest the optimum position of the quantum well (QW) in blue InGaN/GaN LEDs with $Ag/SiO_2$ CS NPs for practical application.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.9-14
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• 2011

A spectroscopic measuring system was developed in order to determine optical gain of gas laser discharge for any optical transitions between 190[nm] and 800[nm] without laser resonator. With an image optical system and a feedback optical system emission light of laser discharge are entered in a monochromator and received at a photomultiplier. Subsequently optical gain and line intensity are measured.