• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.193-193
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• 2008

In this paper, a MMIC diplexer with a low pass and high pass filter are designed and fabricated using an InGaP/GaAs process. The design of this diplexer is based on its stabilization of the low insertion loss since it is important in the in-building system (IBS). The IBS integrates wire and wireless signal between the cable television (CATV) and the personal communication system. In this design, a dual-mode operation of diplexer is fabricated with the frequency of 0 Hz to 900 MHz and 1.7 GHz to 2.2 GHz for CATV and personal communication. respectively. The topolygy of the designed diplexer is based on the L-C filter. This diplexer fabricated by nanoENS Inc. which is foundry service company, was measured by using the facilities of the Kwangwoon University RFIC center. The fabricated chip size is $1.6\times1.4mm^2$ and it has abroad frequency range from 0 Hz to 2.2 GHz.

• Korean Journal of Materials Research
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• v.4 no.6
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• pp.687-694
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• 1994

Heteroepitaxial InP/GaAs layers were grown using the selective liquid phase epitaxy (SLPE) technique. It was observed that the optimum LPE conditions were $660^{\circ}C$ growth temperature, $5^{\circ}C$ supercooling, and $0.4^{\circ}C$/min cooling rate. Maximum expitaxial layer overgrowth (ELO) of 110-160$\mu \textrm{m}$ was obtained when the seed was aligned along (112) orientation. Initial melt-back of the substrate was observed but limited to the seed region so that flat In-Ga-As-P layers were grpwn throughout the GaAs substrates. The InP/GaAs heteroepitaxial structure could be obtained by growing an additional InP layer on top of the In-Ga-As-P layer.

• Journal of the Korean Vacuum Society
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• v.4 no.S1
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• pp.168-173
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• 1995

$GaxIn{1_x}As$ epitaxial layers were grown by a simplified hydrode vapor phase epitaxy(VPE) method bsed on the utilization of Ga/In alloy as the source metal. The effects of a wide range of experimental variables(i.e.,inlet mole fraction of HCI, deposition temperature, Ga/In alloy composition) on the ternary composition and growth rate were investigated. Layers of $Ga_{0.47}In_{0.53}As$ lattice matched to InP were successfully grown from alloys containing 5 to 8 at.% Ga. These layers were used to produce state-of-the art p-i-n photodetectors having the following characteristics: dark current, $I_d$(-5V) = 10-20 nA: responsivity, R=0.84-0.86 A/W; dark current, Id(-5V)=10-20 nA; responsivity, R=0.84-0.86 A/W; capacitance, C=0.88-0.92 pF; breakdown voltage, $V_b$ >40V. This study demonstrated for the first time that a simplified hydride VPE process with a Ga/In alloy source is capable of producing device quality epitaxial layers.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.895-898
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• 2014

The wavelength dependence of the photoacoustic signal for n-type GaAs semiconductors in the region of the band-gap energies was investigated. The significant changes in the phase and amplitude of the photoacoustic signal near the band-gap absorption wavelengths were observed to occur when the Si-doping densities in GaAs were varied. Particularly, the first derivatives of the photoacoustic phase vs. wavelength graphs were evaluated and fitted with single Gaussian functions. The peak centers and the widths of the Gaussian curves clearly showed linear relationships with the log values of the Si-doping densities in n-type GaAs semiconductors. It is proposed that the wavelength-dependent PA spectroscopy can be used as a simple and nondestructive method for measuring the doping densities in bulk semiconductors.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.39-46
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• 1996

In AlGaAs/GaAs HBT the temperature dependence of DC parameters was investigated over the temperature range between 95K and 580K. The temperature dependence of DC parameters depends on the relative contribution of each of the current components suc as emitter-injection-current, base-injection-current, bulk recombination current, interface recombination curretn, thermal generation ecurrent and avalanche current due to impact ionization within the collector space charge layer in a specific temperature. In this paper we investigated the temperature effects on DC parameters such as V$_{BE,ON}$ current gain, input and output characteristics, V$_{CE, OFF}$, R$_{E}$, R$_{C}$ and analyzed the origins, and extracted the qualitativ econditions for a stable HBTs against the temperature variation. Finally, in order to keep HBTs stable with respect to the variation of temperature, the valance-band-energy-discontinuity at emitter-base heterojunction should be large enough to enhance the effect of carrier suppression at a relatively high temperature. In addition the recombination centers, especially around collector junction, should be removed and the area of emitter and collector junction should be identical as well.

• Journal of electromagnetic engineering and science
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• v.4 no.1
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• pp.37-42
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• 2004

In this paper, LNB(low noise block) downconverter MMIC is designed for Ku-band satellite communication system using InGaP/GaAs HBT high linear process. Designed MMIC consists of low noise amplifier, double balanced mixer, and IF amplifier with a total chip area of 2.6${\times}$1.1 $\textrm{mm}^2$. Designed MMIC has the characteristics of over 37.5 ㏈ conversion gain, 14 ㏈ noise figure, ripple of 3 ㏈, and output-referred $P_{1dB}$TEX>(1 ㏈ compression power) of 2.5 ㏈m with total power dissipation of 3 V, 50 mA.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.5
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• pp.285-290
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• 2015

The phase change memory material is an active element in phase change memory and exhibits reversible phase transition behavior by thermal energy input. The doping of the phase change memory material with Ga leads to the increase of its crystallization temperature and the improvement of its amorphous stability. In this study, we investigated the effect of GaGe sputtering power on the formation of the phase change memory material including Ga. The deposition rate linearly increased to a maximum of 127 nm and the surface roughness remained uniform as the GaGe sputtering power increased in the range from 0 to 75 W. The Ga concentration in the thin film material abruptly increased at the critical sputtering power of 60 W. This influence of GaGe sputtering power was confirmed to result from a combined sputtering-evaporation process of Ga occurring due to the low melting point of Ga ($29.77^{\circ}C$).

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1280-1282
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• 1993

We investigated theoretically the current-voltage characteristics of resonant tunneling diodes with a single quantum well structure, using a self-consistent method. This method is a numerical analysis which is able to include the effects of the undoped spacer layer and the band bending by charge accumulation and depletion on the contact layers, so that it is better suited to explain experimental results. The structure used is an $Al_{0.5}Ga_{0.5}$As/GaAs/$Al_{0.5}Ga_{0.5}As$ single quantum well. In this work, we estimate the theoretical current-voltage characteristics, and then, the dependence of the current-voltage curves on the thickness of undoped spacer layers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1113-1123
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• 1999

The purpose of this study was to see the effect of anti inflammatory and analgesic action of the glucosamine hydrochloride(GA HCl) or taurine. Male Sprague Dawley rats(100~250g) and ICR mice(20 ~30g) were used. Experimental groups were divided into seven groups, one control group given as saline and six groups given as oral administration of GA HCl or taurine; GA HCl 250mg/kg, b.w group, taurine 250mg/kg, b.w group, GA HCl 250mg/kg, b.w＋taurine 250mg/kg, b.w group, GA HCl 500mg/kg, b.w group, taurine 500mg/kg, b.w group, GA HCl 500mg/kg, b.w＋taurine 500mg/kg, b.w group. Carrageenan induced edema test were shown to be significantly inhibited in the GA HCl 250mg/kg group and taurine 250mg/kg group compared to the control group, but the GA HCl 500mg/kg＋taurine 500mg/kg group were significantly inhibited than the control group. Capillary permeability test were shown to be sig nificantly inhibited in the taurine 500mg/kg group, but the GA HCl 500mg/kg＋taurine 500mg/kg group were significantly inhibited than the control group. Leucocyte emigration test were shown to be significantly inhibited in the GA HCl 250mg/kg＋ taurine 250mg/kg group and GA HCl 500mg/kg＋taurine 500mg/kg group compared to the control group. Acetic acid, Phenyl p benzoquinone writhing syndrome were shown to be significantly inhibited in the GA HCl 500mg/kg＋taurine 500mg/kg group compared to the control group. Inhibitory action against COX 1 and COX 2 were not significantly inhibited in the experimental group. These results suggest that the combined administration of the GA HCl and taurine have potential action in anti inflammatory and analgesic action.

• The Journal of Korean Physical Therapy
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• v.14 no.2
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• pp.234-249
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• 2002

This study was performed, using c-fos and Substance P, to investigate the effect of GaAlAs laser on acute pain model induced by wound in lumbar region's spinal level. The test group was divided into control and experimental group. Control group is shamed group(c-fos and substance P expression after non-irradiation by a GaAlAs laser), The experimental group was divided into two subgroups: one is experimental group I (c-fos expression after irradiation by a GaAlAs laser), and the other is experimental group II (substance P expression after irradiation by a GaAlAs laser). The results of this study were as following: 1. The numbers of c-fos immunoreactive neuron in spinal cord was increased markedly 1 day after wound, and decreased gradually from 1 day to 2 days in wound with GaAlAs laser irradiation. 2. The changes of the average percentages of substance P immunoreactive neurons in spinal cord was increased markedly 1 day after wound, and decreased gradually from 1 day to 2 days in wound with GaAlAs laser irradiation. Therefore, decreasing the changes of c-fos and substance P expression after irradiation by a GaAlAs laser indicates and GaAlAs laser have effect on pain control.