• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.185-188
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• 1996

The doped n-type $Al_{x}Ga_{1-x}Sb$ crystals were grown by the vertical Bridgman method at composition ratio x=0, x=0.1, x=02 respectively. The lattice constants of the $Al_{x}Ga_{1-x}Sb$ crystals were 6.096${\AA}$, 6.097${\AA}$, 6.106${\AA}$ at composition ratio respectively. The carrier concentration, the resistivity, and the carrier mobility measured by the Van der Pauw method at x-0 were n≡1 x $10^{17}$$cm^{-3}$, $\rho$≡0.15 ${\Omega}$-cm, ${\mu}$$_{n}$≡500 $\textrm{cm}^2$$V^{-1}$$sec^{-1}$ at 300K. The carrier concentration, the resistivity, and the carrier mobility measured by the Van der Pauw method at x=0.1 were n≡2.96 x $10^{15}$$cm^{-3}$, $\rho$≡103 $\textrm{cm}^2$$V^{-1}$$sec^{-1}$ at 300K.

• Electrical & Electronic Materials
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• v.9 no.9
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• pp.885-890
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• 1996

Undoped p-type and Te doped n-type GaSb crystals were grown by the vertical Bridgman method. The lattice constant of the GaSb crystals was 6.096.+-.000373.angs.. The carrier concentration, the resistivity, and the carrier mobility measured by the van der Pauw method were p.iden.8*10$^{16}$ c $m^{-3}$ , .rho..iden.0.20 .ohm.-cm, .mu.$_{p}$ .iden.400c $m^{2}$ $V^{-1}$ se $c^{-1}$ for p-type, n.iden.1*10$^{17}$ c $m^{-3}$ , .rho..iden.0.15 .ohm.-cm, .mu.$_{n}$ .iden.500c $m^{2}$ $V^{-1}$ se $c^{-1}$ for n-type at 300K. In case of treatment with metal ion of R $u^{+3}$, P $t^{+4}$, the carrier concentration, resistivity and carrier mobility of the GaSb crystals were p.iden.2*10$^{17}$ c $m^{-3}$ , .rho..iden.0.08.ohm.-cm, .mu.$_{p}$ .iden.420c $m^{2}$ $V^{-1}$ se $c^{-1}$ for p-type, n.iden.2.5*10$^{17}$ c $m^{-3}$ , .rho..iden.0.07.ohm.-cm, .mu.$_{n}$ .iden.520c $m^{2}$ $V^{-1}$ se $c^{-1}$ for n-type respectively. GaSb crystals had a tendency to lower resistivity and higher mobility, for surface treatment with metal ion effectively diminished surface recombination centers.s.

• Current Optics and Photonics
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• v.2 no.5
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• pp.468-473
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• 2018

We investigate the temperature dependence of efficiency droop in InGaN/GaN multiple-quantum-well (MQW) blue light-emitting diodes (LEDs) in the temperature range from 20 to $80^{\circ}C$. When the external quantum efficiency (EQE) and the wall-plug efficiency (WPE) of the LED sample were measured as injection current and temperature varied, the droop of EQE and WPE was found to be reduced with increasing temperature. As the temperature increased from 20 to $80^{\circ}C$, the droop ratio of EQE was decreased from 16% to 14%. This reduction in efficiency droop with temperature can be interpreted by a temperature-dependent carrier distribution in the MQWs. When the carrier distribution and radiative recombination rate in MQWs were simulated and compared for different temperatures, the carrier distribution was found to become increasingly homogeneous as the temperature increased, which is believed to partly contribute to the reduction in efficiency droop with increasing temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.586-591
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• 2004

We studied the dependence of hot-tarrier-induced degradation characteristics on nitrogen concentration in NO(Nitrided-Oxide) gate of nMOS, under ac and dc stresses. The $\Delta$V$_{t}$ and $\Delta$G$_{m}$ dependence of nitrogen concentration were observed, We observed that device degradation was suppressed significantly when the nitrogen concentration in the gate was increased. Compared to $N_2$O oxynitride, NO oxynitride gate devices show a smaller sensitivity to ac stress frequency. Results suggest that the improved at-hot carrier immunity of the device with NO gate may be due to the significantly suppressed interface state generation and neutral trap generation during stress.ess.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.4
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• pp.180-186
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• 2023

Positive bias temperature instability (PBTI) degradation of n⁺ and p⁺ poly-Si gate high-voltage(HV) SiO2 dielectric nMOSFETs was investigated. Unlike the expectation that degradation of n⁺/nMOSFET will be greater than p⁺/nMOSFET owing to the oxide electric field caused by the gate material difference, the magnitude of the PBTI degradation was greater for the p⁺/nMOSFET than for the n⁺/nMOSFET. To analyze the cause, the interface state and oxide charge were extracted for each case, respectively. Also, the carrier injection and trapping mechanism were analyzed using the carrier separation method. As a result, it has been verified that hole injection and trapping by the p⁺ poly-Si gate accelerates the degradation of p⁺/nMOSFET. The carrier injection and trapping processes of the n⁺ and p⁺ poly-Si gate high-voltage nMOSFETs in PBTI are detailed in this paper.

• Current Optics and Photonics
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• v.3 no.2
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• pp.164-171
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• 2019

Photoluminescence (PL) properties of GaN-based light-emitting diodes (LEDs) were analyzed to study the effects of carrier leakage on the luminescence properties at room temperature. The electrical leakage and PL properties were compared for LEDs showing leakages at forward bias and an LED with an intentional leakage path formed by connecting a parallel resistance of various values. The leakages at the forward bias, which could be observed from the current-voltage characteristics, resulted in an increase in the excitation laser power density for the maximum PL efficiency (ratio of PL intensity to excitation power) as well as a reduction in the PL intensity. The effect of carrier leakages on PL properties was similar to the change in PL properties owing to a reduction of the photovoltage by a reverse current since the direction of the carrier movement under photoexcitation is identical to that of the reverse current. Valid relations between PL properties and electrical properties were observed as the PL properties deteriorated with an increase in the carrier leakage. The results imply that the PL properties of LED chips can be an indicator of the electrical properties of LEDs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.66-69
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• 2001

Effect of $N_2$ flow rate on properties of GaN thin films grown by plasma-enhanced molecular beam epitaxy(PEMBE) was discussed to optimize the quality of thin films. It was found that at low $N_2$ flow rate indicating high III/V flux ratio, the growth rate of GaN thin films was controlled by $N_2$ flux, and at high $N_2$ flow rate the growth rate was not controlled by $N_2$ flux any longer. It was also found that III/V flux ratio affected film quality. The film grown at higher $N_2$ flow rate showed low background carrier concentration, higher carrier mobility, and narrow FWHM in band-edge emission of low temperature PL. It is thought that the film in more Ga flux region was grown by 2-dimensional layer-by-layer growth mode, and the film in more nitrogen region was grown by 3-D island growth mode. All samples exhibited a good crystallinity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.575-578
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• 2002

In this paper, we discuss carrier trapping model and trap characteristics of nitrided oxide thin film. Based on the experimental results, the carrier trapping model for system having multi-traps is proposed and is fitted with experimental data in order to determine trap parameter of nitride oxide and O2 annealed nitrided oxide. As a results of curve fitting, the heavy nitridation of oxide introduces three kinds of traps with capture cross section $\sigma$n1=1.48$\times$10$^{-17}$ $\textrm{cm}^2$, $\sigma$n2=1.51$\times$10$^{-19}$ $\textrm{cm}^2$, $\sigma$p=1.53$\times$10$^{-18}$ $\textrm{cm}^2$ and corresponding trap densities Nnl=2.66$\times$10$^{12}$ Cm$^{-2}$ , Nn2=1.32$\times$10$^{12}$ Cm$^{-2}$ , Np=8.35$\times$10$^{12}$ Cm$^{-2}$ .

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.245-255
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• 2009

Effect of CO$_2$ concentration on reduction reactivity of oxygen carrier particles for chemical-looping combustor were investigated. Four particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN702-1250, were used as oxygen carrier particles and two kinds of gases (CH$_4$, 5%, N$_2$ balance and CH$_4$ 5%, CO$_2$ balance) were used as reactants for reduction. For all oxygen carrier particles, higher maximum conversion, reduction rate, oxygen transfer capacity, and oxygen transfer rate were achieved when we used N$_2$ balance gas. OCN601-650 particle showed higher oxygen transfer rate for all gases than other particles, and therefore we selected OCN601-650 particle as the best candidate. For all particles, lower carbon depositions were observed when we used CO$_2$ balance gas.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.412-420
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• 2016

Effect of $H_2S$ on reactivity of oxygen carrier was measured and discussed using fluidized bed reactor and SDN70 oxygen carrier. We could get 100% of fuel conversion and $CO_2$ selectivity even though $H_2S$ containing simulated syngas was used as fuel for reduction. Absorbed sulfur was released during oxidation and $N_2$ purge step after oxidation as $SO_2$ form. We could get 100% of fuel conversion and $CO_2$ selectivity during cyclic reduction-oxidation tests up to 10th cycle. However, only 6~7% of sulfur can be removed during oxidation and $N_2$ purge step and 93~94% of sulfur was accumulated in the oxygen carrier. Therefore we could conclude that total removal of sulfur was not possible. $SO_2$ emission during oxidation decreased as the number of cycle increased. Therefore we could expect that the reactivity of oxygen carrier will be decreased with time.