• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.120-120
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• 2003

The metallic oxide nanomaterials including ZnO, Ga$_2$O$_3$, TiO$_2$, and SnO$_2$ have been synthesized by a number of methods including laser ablation, arc discharge, thermal annealing procedure, catalytic growth processes, and vapor transport. We have been interested in preparing the nanomaterials of Ga$_2$O$_3$, which is a wide band gap semiconductor (E$_{g}$ =4.9 eV) and used as insulating oxide layer for all gallium-based semiconductor. Ga$_2$O$_3$ is stable at high temperature and a transparent oxide, which has potential application in optoelectronic devices. The Ga$_2$O$_3$ nanoparticles and nanobelts were produced using GaN single crystals, which were grown by flux method inside SUS$^{TM}$ cell using a Na flux and exhibit plate-like morphologies with 4 ~ 5 mm in size. In these experiments, the conventional electric furnace was used. GaN single crystals were pulverized in form of powder for the growth of Ga$_2$O$_3$ nanomaterials. The structure, morphology and composition of the products were studied mainly by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM).).

• 전기전자학회논문지
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• 제22권1호
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• pp.180-184
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• 2018

산화갈륨 ($Ga_2O_3$)과 탄화규소 (SiC)는 넓은 밴드 갭 ($Ga_2O_3-4.8{\sim}4.9eV$, SiC-3.3 eV)과 높은 임계전압을 갖는 물질로서 높은 항복 전압을 허용한다. 수직 DMOSFET 수평구조에 비해 높은 항복전압 특성을 갖기 때문에 고전압 전력소자에 많이 적용되는 구조이다. 본 연구에서는 2차원 소자 시뮬레이션 (2D-Simulation)을 사용하여 $Ga_2O_3$와 4H-SiC 수직 DMOSFET의 구조를 설계하였으며, 항복전압과 저항이 갖는 trade-off에 관한 파라미터를 분석하여 최적화 설계하였다. 그 결과, 제안된 4H-SiC와 $Ga_2O_3$ 수직 DMOSFET구조는 각각 ~1380 V 및 ~1420 V의 항복 전압을 가지며, 낮은 게이트 전압에서의 $Ga_2O_3-DMOSFET$이 보다 낮은 온-저항을 갖고 있지만, 게이트 전압이 높으면 4H-SiC-DMOSFET가 보다 낮은 온-저항을 갖을 수 있음을 확인하였다. 따라서 적절한 구조와 gate 전압 rating에 따라 소자 구조 및 gate dielectric등에 대한 심화 연구가 요구될 것으로 판단된다.

• 전기전자학회논문지
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• 제22권2호
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• pp.427-431
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• 2018

본 논문에서는 최근 전력반도체 산업에서 활용되어지는 와이드밴드갭 반도체 중에 하나인 $Ga_2O_3$를 이용한 에피웨이퍼 성장에 관련되어 서술하였다. GaN 성장시 활용되어지는 HVPE법을 이용하여 Sn이 도핑된 $Ga_2O_3$ 기판웨이퍼에 평균 $5.3{\mu}m$ 두께로 성장시켰다. 일반적으로 화합물반도체의 에피 두께가 $5{\mu}m$일 경우 SiC의 경우 600V 전력반도체소자를 제작할 수 있으며, $Ga_2O_3$ 에피웨이퍼의 경우에는 1000V이상의 전력소자를 제작할 수 있다. 성장된 에피웨이퍼의 J-V 측정 결과 $2.9-7.7m{\Omega}{\cdot}cm^2$의 온저항을 얻을 수 있었으며, 역방향의 경우 상당히 높은 전압에서도 누설전류가 거의 없음을 알 수 있었다.

• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.59-63
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• 2012

Ga2O3-core/CdO-shell nanowires were synthesized by a two step process comprising thermal evaporation of GaN powders and sputter-deposition of CdO. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses revealed that the cores and the shells of the annealed coaxial nanowires were single crystal of monoclinic Ga2O3 and FCC CdO, respectively. As-synthesized Ga2O3 nanowires showed a broad emission band at approximately 460 nm in the blue region. The blue emission intensity of the Ga2O3 nanowires was slightly decreased by CdO coating, but it was significantly increased by subsequent thermal annealing in a reducing atmosphere. The major emission peak was also shifted from ~500 nm by annealing in a reducing atmosphere, which is attributed to the increases in the Cd interstitial and O vacancy concentrations in the cores.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.12-13
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• 2006

$Ga_2O_3$ is associated with the fabrication of thin window layer of solar cell. Usually, $Ga_2O_3$ is synthesized from Ga-metal oxidation method and GaN mono-crystal heat treatment method. We synthesized $Ga_2O_3$ powder using two methods and analyzed powder using latter method compared with powder by former method. XPS, XRD, IR analysis are conducted. XPS result, surface of GaN powder is almost oxidized to $Ga_2O_3$ at $1124^{\circ}C$ heat treatment and XRD and IR result, the inside of GaN powder is dramatically oxidized at $1124^{\circ}C{\sim}1300^{\circ}C$.

• 한국응용과학기술학회지
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• 제21권3호
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• pp.231-237
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• 2004

Ga-MFI was synthesized by a hydrothermal process at atmospheric pressure. The effect of mole ratios of reactants on crystallization was also investigated thoroughly. The characteristics of synthesized Ga-MFI was compared with ZSM-5. The synthesis of Ga-MFI was carried out with five different mole-compositions of $\underline{a}SiO_2-\underline{b}Ga_2O_3-\underline{c}Na_2O-\underline{d}TPA_2o-\underline{e}H_2O$. The synthesized Ga-MFI and ZSM-5 were characterized by XRD and FT-IR. The inorganic cation ($Na^+$) and water played an important role in crystallinity and the organic cation ($TPA^+$) as a template played a great influence on yields. With the increase in the amount of $Ga^{3+}$, crystallization time was increased. With a fixed $SiO_2/Ga_2O_3$ ratio of 400, the optimum reaction condition was obtained at $H_2O/SiO_2$=30${\sim}$35, $Na_2O/SiO_2$=0.5${\sim}$0.6, and $TPA_2O/Na_2O$=1${\sim}$1.25. In these cases, the crystallinity and yield were more than 95% and 90%, respectively. By comparing IR spectrum of Ga-MFI with those of ZSM-5 and silicalite, it was found that Ga-MFI showed a unique peak at 970 $cm^{-1}$, which may be used to identify Ga-MFI from ZSM-5 and silicalite.

• 한국세라믹학회지
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• 제35권11호
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• pp.1148-1154
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• 1998

Ga K-edge EXAFS spectra of PbO-Ga2O3 glasses were recorded at liquid nitrogen temperature and analyz-ed in order to quantitatively understand the medium-range-order arrangement around gallium in the glasses. The second peak was generated from a backscattering of the neighbor balliums and the Ga-Ga distance is ~3.13 A with Ga coordination number of ~2.7 Therefore GaO4 tetrahedra are connected through the cor-ner~sharing mode and form their own clusters made of the tetrahedra sharing more than 3 corners while some chains or rings are also present. These connection schemes of the GaO4 tetrahedra are believed to form the substantial part of the network structure.

• 한국수소및신에너지학회논문집
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• 제3권2호
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• pp.25-33
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• 1992

With the aim to obtain $TiO_2$ films with an increased photorespones and absorbance in the visible region of the solar spectrum, the direct oxidation of titanium alloys were performed. In this study, $Ti-Ga_2O_3$ alloy was prepared by mixing, pressing and arc melting of appropriate amounts of titanium and $Ga_2O_3$ powder. Electrochemical measurements were performed in three electrode cell using electrolyte of 1M NaOH solution. The oxide films on $Ti-Ga_2O_3$ alloy was composed of $Ti_2O$, TiO, $TiO_2$, $Ga_2TiO_5$. The free energy efficiency (${\eta}e$) of $Ti-Ga_2O_3$ oxide films had 0.8~1.3 % and were increased with the increase of $Ga_2O_3$ content up to 10wt %. The onset potential ($V_{on}$) had -0.8V~0.9V ranges and were shifted to anodic direction with the increase of $Ga_2O_3$ content. The spectral response of Ti-$Ga_2O_3$ oxides were similar to the response of the $TiO_2$ and their $E_g$ were observed to 2.90~3.0eV. Variations of onset potential($V_{on}$) associated with electrolyte pH were -59mV/pH. This probably reflects the nature of the bonding of $OH^-$ ion to the $TiO_2$ surface, a common phenomena in the transition-metal oxides.

• The Korean Journal of Ceramics
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• 제3권2호
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• pp.134-138
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• 1997

$Dy^{3+}-(or Tm^{3+}-)$ doped $Ga_2O_3 \;and\; ZnGa_2O_4$ phosphors were prepared using the solid state reaction method to investigate their photoluminescent characteristics. Under 254 nm excitation, $Dy^{3+}-doped Ga2_O_3$ exhibited two emission bands of 460~505nm and 570~600nm. On the other hand, $Dy^{3+}-(or Tm^{3+}-)$ doped $ZnGa_2O_4 $phosphors exhibited a broad-band emission extending from 330 nm to 610 nm, peaking at about 430 nm(or 370 nm). In this study, an emission peak shift of nealy 50 nm towards longer wavelength region was observed with $Dy^{3+}$ doping in the $ZnGa_2O_4 $.

• 조명전기설비학회논문지
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• 제24권4호
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• pp.10-16
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• 2010

본 논문에서는 ZnO와 $Ga_2O_3$ 분말을 1 : 1의 mole비로 혼합하고 여기에 Mn을 첨가하여 Ar 주입 상태와 진공 상태에서 조성된 $ZnGa_2O_4$ : Mn을 합성하였다. 제작된 $ZnGa_2O_4$ : Mn의 발광 스펙트럼 관찰을 하여 산소의 성분 변화가 발광 특성에 미치는 영향을 설명하였다. 또한 저온의 Photoluminescence(PL) 스펙트럼으로부터 Mn의 site symmetry가 발광 스펙트럼에 미치는 영향을 설명하였다.