• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.919-926
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• 2021

In this paper, a study was conducted on the miniaturization of an e-Mobility battery charger module using GaN-FET. GaN-FET is one of the types of WBG devices, and it is a device that exceeds the performance of existing Si power semiconductors. In particular, GaN-FET has the advantage of small packaging size and high switching frequency operation, which is advantageous for miniaturization of power converters. Therefore, a bidirectional DC/DC converter module for e-mobility charging using GaN-FET was developed. To apply to the converter to be developed, analysis is performed on the characteristics of GaN-FET, and after manufacturing a prototype of a bidirectional DC/DC converter module, the efficiency and temperature data of the power converter are analyzed to verify its feasibility.

• Korean Journal of Materials Research
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• v.17 no.1
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• pp.1-5
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• 2007

GaN thin fan were grown by spin coated colloidal GaOOH precursor. Polycrystalline GaNs with crystalline size of $10{\sim}100nm$ were grown on $SiO_2$ substrate. The shape of crystallite above $900^{\circ}C$ had the hexagonal plate and column type. X-ray diffraction patterns for them correspond to those of the hexagonal wurtzite GaN. With increasing droplets. i.e, thickness of deposited layers, XRD intensity increased. PL (photoluminescence) spectrum consisted with an weak near band-edge emission at 3.45 eV and a broad donor-acceptor emission band at 3.32 eV. From the low temperature PL measurement on GaN grown at $800^{\circ}C$ that the shallow donor-acceptor recombination induced emission was more intense than the near band-edge excitonic emission.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.4
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• pp.22-27
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• 1992

The cyclic voltammogram characteristics at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ ceramics/(($10^{-3}$M KCI + p-Si powders) and /(($10^{-4}$M CsNO$_3$ + n-GaAs powders) suspension interfaces have been studied using the microelectrophoresis and the cyclic voltammetric method. The negatively charged ions are specifically absorbed on the virgin and the magnetized SrO${\cdot}6Fe_{2}O_{3}$ ceramics surfaces. The zeta potentials of the p-Si and n-GaAs colloidal semiconductors are + 41mV and -44.8mV, respectively. The magnetization effects act as potential barriers at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ interfaces. The positivelely charged p-Si and the negatively charged n-GaAs colloidal semiconductors act as potential barriers at the virgin SrO${\cdot}6Fe_{2}O_{3}$ interfaces. On the other hand, the charged p-Si and n-GaAs colloidal semiconductors act as potential barrier scavengers at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ interfaces. The magnetization effects and the charged colloidal semiconductor effects are irreversible and interdependent.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.772-775
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• 2013

We have grown a p-GaN film on sapphire by MOCVD and explored the post-annealing effort on the film after depositing a $2500{\AA}$ thick $SiO_2$ protective layer on it. By etching the $SiO_2$ protective film after the heat treatment, the hole concentration was measured, and compared with the data values before the heat treatment. In addition to the concentration, the hole mobility was also monitored while varying the atmospheric gas ratio of $N_2$ and $O_2$, the rapid thermal annealing temperatures ($750^{\circ}C$ and $650^{\circ}C$) and times (1 to 15 min.) In order to investigate the optical and structural properties of the film, room temperature and low temperature PL measurements were conducted.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.460-466
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• 1999

The deep level electron traps in AP-MOCVD GaAs/undoped Al\ulcornerGa\ulcornerAs/n-type GaAs heterostructures have been investigated by means of Deep Level Transient Spectroscopy DLTS). In terms of the experimental procedure, GaAs/undoped Al\ulcornerGa\ulcornerAs/n-type GaAs heterostructures were deposited on 2" undoped semi-insulating GaAs wafers by the AP-MOCVD method at $650^{\circ}C$ with TMGa, AsH3, TMAl, and SiH4 gases. The n-type GaAs conduction layers were doped with Si to the target concentration of about 2$\times$10\ulcornercm\ulcorner. The Al content was targeted to x=0.5 and the thicknesses of Al\ulcornerGa\ulcornerAs layers were targeted from 0 to 40 nm. In order to investigate the electrical characteristics, an array of Schottky diodes was built on the heterostructures by the lift-off process and Al thermal evaporation. Among the key results of this experiment, the deep level electron traps at 0.742~0.777 eV and 0.359~0.680 eV were observed in the heterostructures; however, only a 0.787 eV level was detected in n-type GaAs samples without the Al\ulcornerGa\ulcornerAs overlayer. It may be concluded that the 0.787 eV level is an EL2 level and that the 0.742~0.777 eV levels are related to EL2 and residual oxygen impurities which are usually found in MOCVD GaAs and Al\ulcornerGa\ulcornerAs materials grown at $630~660^{\circ}C$. The 0.359~0.680 eV levels may be due to the defects related with the al-O complex and residual Si impurities which are also usually known to exist in the MOCVD materials. Particularly, as the Si doping concentration in the n-type GaAs layer increased, the electron trap concentrations in the heterostructure materials and the magnitude of the C-V hysteresis in the Schottky diodes also increased, indicating that all are intimately related.ated.

• Korean Journal of Materials Research
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• v.8 no.1
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• pp.38-44
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• 1998

RF 스퍼터링법으로 (001)Si 기판위에 AIN완충층을 성장하고, 그 위에 HVPE법으로 GaN를 성장하였다. GaN의 성장률은 103$0^{\circ}C$의 온도에서 AIN완충충의 두께가 각각 500$\AA$과 2000$\AA$ 일때 65$\mu\textrm{m}$/hr와 84$\mu\textrm{m}$/hr로서 AIN완충층의 두께가 증가함에 따라 증가하였다. AIN완충층위에서 GaN의 성장초기에는 수 $\mu\textrm{m}$크기의 결정들이 임의의 방향으로 성장된 후 성장시간이 경과함에 따라 수평방향으로의 성장에 의하여 합쳐지게 되며, c-축 방향으로 배향된 평탄한 표면을 갖는 다결정체가 성장되었다. 20K의 온도에서 측정된 광루미네센스(PL)스펙트럼에서는 3.482eV에서 자유여지자에 의한 발광과 3.7472eV에서 반치폭이 9.6meV인 도너 구속여기자 발광 및 3.27eV 부근에서의 도너-억셉터 쌍 사이의 재결합과 LO포는 복제에 의한 발광이 나타났다. 그러나 2.2eV부근에서의 황색발광은 관찰되지 않았다.

• Transactions on Electrical and Electronic Materials
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• v.14 no.1
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• pp.32-35
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• 2013

In this paper, a manufacturing process was developed for fabricating high-quality AlGaN/GaN high electron mobility transistors (HEMTs) on silicon carbide (SiC) substrates. Various conditions and processing methods regarding the ohmic contact and pre-metal-deposition $BCl_3$ etching processes were evaluated in terms of the device performance. In order to obtain a good ohmic contact performance, we tested a Ti/Al/Ta/Au ohmic contact metallization scheme under different rapid thermal annealing (RTA) temperature and time. A $BCl_3$-based reactive-ion etching (RIE) method was performed before the ohmic metallization, since this approach was shown to produce a better ohmic contact compared to the as-fabricated HEMTs. A HEMT with a 0.5 ${\mu}m$ gate length was fabricated using this novel manufacturing process, which exhibits a maximum drain current density of 720 mA/mm and a peak transconductance of 235 mS/mm. The X-band output power density was 6.4 W/mm with a 53% power added efficiency (PAE).

• Journal of the Semiconductor & Display Technology
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• v.19 no.4
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• pp.99-104
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• 2020

In this paper, efficiency and loss characteristics of GaN FET were reported by applying it into the QR flyback converter. In particular, for the comparison of efficiency characteristics, QR flyback converter experimental circuits with Si FET and with GaN FET were separately produced in 12W class. As a result of the experiment, the experimental circuit of the QR flyback converter using GaN FET reached a high efficiency of 90% or more when the load power was 2W or more, and the maximum efficiency was observed to be about 92%, and the maximum loss power was about 1.1W. Meanwhile, the efficiency of the experimental circuit with Si FET increased as the input voltage increased, and the maximum efficiency was observed to be about 82% when the load power was 9W or higher, and the maximum loss power was about 2.8W. From the results, it is estimated that that in the case of the experimental circuit applying the GaN FET switch, the power conversion efficiency was improved as the switching loss and conduction loss due to on-resistance were reduced, and the internal loss due to the synchronous rectifier was minimized. Consequently, it is concluded that the GaN FET is suitable for under 20W class power supply unit as a high efficiency power switch.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.6
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• pp.283-287
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• 2002

We have studied Zr(Si)N film as a diffusion barrier between Cu metal and Si substrate for application of interconnection metal in ULSI circuits. Zr(Si)N film was deposited with reactive DC magnetron sputtering system using $Ar/N_2$mixed gas. The value of the resistivity was the lowest for the ZrN film using 29 : 1 of Ar : $N_2$reactant gas ratio at room temperature and decreased with increasing of Si substrate temperature. As the value of ZrN film resistivity was decreased, the direction of crystal growth was toward to (002) plane. The barrier property of ZrN film added with Si was improved. But Si was added too much in ZrN film, the barrier property was degraded. The adhesive property was improved with increasing of Si in ZrN. For the analysis of the film, XRD, Optical microscopy, Scretch tester, so on were used.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1351-1358
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• 2017

In this work, we investigated radiation hardness of GaN-based transistors which are strong candidates for next-generation power electronics. Field effect transistors with three types of gate structures including metal Schottky gate, recessed gate, and p-AlGaN layer gate were fabricated on AlGaN/GaN heterostructure on Si substrate. The devices were irradiated with energetic protons and alpha-particles. The irradiated transistors exhibited the reduction of on-current and the shift of threshold voltage which were attributed to displacement damage by incident energetic particles at high fluence. However, FET operation was still maintained and leakage characteristics were not degraded, suggesting that GaN-based FETs possess high potential for radiation-hardened electronics.