• Transactions on Electrical and Electronic Materials
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• v.12 no.1
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• pp.11-15
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• 2011

In this study, $ZnGa_2O_4$ phosphors in its application to field emission displays and electroluminescence were synthesized through the precipitation method and $Mn^{2+}$ ions. A green luminescence activator, $Cr^{3+}$ ions, and a red luminescence activator were separately doped into $ZnGa_2O_4$, which was then screen printed to an indium tin oxide substrate. The thick films of the $ZnGa_2O_4$ were deposited with the various thicknesses using nano-sized powder. The best luminescence characteristics were shown at a thickness of 60 ${\mu}m$. Additionally, green-emission $ZnGa_2O_4:Mn^{2+}$ and red-emission $ZnGa_2O_4:Cr^{3+}$ phosphor thick films, which have superior characteristics, were manufactured through the screen-printing method. These results indicate that $ZnGa_2O_4$ phosphors prepared through the precipitation method have wide application as phosphor of the full color emission.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.775-779
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• 2006

In this study, sputtered $Al_2O_3$ thin films were evaluated as a passivation layer in the process of InGaN-based blue LEDs in order to improve the brightness of LED lamps. In terms of packaged LED lamps, lamps with $Al_2O_3$ passivation layer emanated higher brightness than those with $SiO_2$ passivation layer, and LED lamps with 90 nm $Al_2O_3$ passivation layer were the brightest among four kinds of lamps. Although lamps with $Al_2O_3$ passivation had a slight increase in operating voltage, their brightness was improved about 13.6 % compare to the lamps made of conventional LEDs without the changes of emitting wavelength.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.575-580
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• 2012

The purpose of this study is to investigate the crystalline structure and optical properties of (GaZn)(NO) powders prepared by solid-state reaction between GaOOH and ZnO mixture under $NH_3$ gas flow. While ammoniation of the GaOOH and ZnO mixture successfully produces the single phase of (GaZn)(NO) solid solution within a GaOOH rich composition of under 50 mol% of ZnO content, this process also produces a powder with coexisting (GaZn)(NO) and ZnO in a ZnO rich composition over 50 mol%. The GaOOH in the starting material was phase-transformed to ${\alpha}$-, ${\beta}-Ga_2O_3$ in the $NH_3$ environment; it was then reacted with ZnO to produce $ZnGa_2O_4$. Finally, the exchange reaction between nitrogen and oxygen atoms at the $ZnGa_2O_4$ powder surface forms a (GaZn)(NO) solid solution. Photoluminescence spectra from the (GaZn)(NO) solid solution consisted of oxygen-related red-emission bands and yellow-, green- and blue-emission bands from the Zn acceptor energy levels in the energy bandgap of the (GaZn)(NO) solid solutions.

• Journal of IKEEE
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• v.25 no.3
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• pp.511-516
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• 2021

The electrical characteristics of AlGaN/GaN/HEMT and MOSHFETs with NiO were studied. The threshold voltage of NiO MOSHFET revealed positive shift of +1.03 V than the -3.79 V of HEMT and negative shift of -1.73 V for SiO₂ MOSHFET. Also, NiO MOSHFET showed better linearity in drain current corresponding to gate voltage and higher transconductance at positive gate voltage than the others. The response of gate pulse with base voltage of -5 V was different for both transistors as HEMT showed 20 % drain current decrease at the frequency range of 0.1 Hz~10 Hz and NiO MOSHFET decreased continuously above 10 Hz.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.462-462
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• 2013

Gallium Oxide (Ga2O3) has been widely investigated for the optoelectronic applications due to its wide bandgap and the optical transparency. Recently, with the development of fabrication techniques in nanometer scale semiconductor materials, there have been an increasing number of extensive reports on the synthesis and characterization of Ga2O3 nano-structures such as nano-wires, nanobelts, and nano-dots. In contrast to typical vaporliquid-solid growth mode with metal catalysts to synthesis 1-dimensional nano-wires, there are several difficulties in fabricating the nanostructures by using sputtering techniques. This is attributed to the fact that relatively low growth temperatures and higher growth rate compared with chemical vapor deposition method. In this study, Ga2O3 chestnut burr were synthesized by using radio-frequency magnetron sputtering method. In contrast to typical sputtering method with sintered ceramic target, a Ga2O3 powder (99.99% purity) was used as a sputtering target. Several samples were prepared with varying the growth parameters, especially he growth time and the growth temperature to investigate the growth mechanism. Samples were characterized by using XRD, SEM, and PL measurements. In this presentation, the details of fabrication process and physical properties of Ga2O3 nano chestnut burr will be reported.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.22 no.1
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• pp.45-51
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• 1977

The studies were carried to know the effects of GA$_3$, Ethrel and $H_2O$$_2$ on dormancy and germination in ginseng seeds. GA$_3$ stimulated the embryo growth and increased dehiscent (Kaekapp) ratio of the seeds for more than Ethrel and $H_2O$$_2$ GA$_3$ not only increased germination ratio but also shortened the period of germination. Ethrel and $H_2O$$_2$ showed no effects on the germination and there were no significant differences among the treatment levels of GA$_3$. The slow germination of ginseng seeds seemed to be mainly due to the dormancy of endosperm or seed coat rather than of embryo.

• 전자공학회논문지 IE
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• v.46 no.3
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• pp.1-5
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• 2009

In this paper, we study the electrical characteristics of $RuO_2$/n-GaN Schottky diodes fabricated by using electrochemical metallization. The solution for GaN Schottky electrodes of $RuO_2$ is perchloric acid($HClO_4$). Thickness of $RuO_2$ layer depend on supplied voltage and dipping time. We verified the possibility of the rectifying and non-rectifying devices' electrode which was depend on the thickness of $RuO_2$ layer.

• Journal of IKEEE
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• v.28 no.1
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• pp.104-109
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• 2024

In this research, we explored the influence of post-annealing atmospheres on the electrical properties of Ga₂O₃/SiC heterojunction diodes. We fabricated Ga₂O₃/SiC heterojunction diodes by RF sputtering and after the fabrication the post-annealing in various gas atmospheres was performed. We measured the changes in deep-level defects using Deep Level Transient Spectroscopy (DLTS) and we conducted an electrical characteristic of J-V measurement and Hall measurement to analyzed the effects of annealing atmosphere on Ga₂O₃/SiC heterojunction diode. In the N₂ annealed devices, the highest on-state current was measured as 3.06 × 10^-2 A/cm^2, and an increase in carrier concentration of 3.8 × 10¹⁴ cm^-3 was observed. This confirms that the variations in deep level defects due to the post-annealing atmosphere can influence the electrical properties.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.2
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• pp.73-77
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• 2021

Ga-doped ZnO thin films by RF magnetron sputtering process were synthesized according to the deposition conditions of O2 and Ar atmosphere gases, and rapid heat treatment (RTA) was performed at 600℃ in an N2 atmosphere. The thickness of the deposited ZnO : Ga thin film was measured, the crystal phase was investigated by XRD pattern analysis, and the microstructure of the thin film was observed by FE-SEM and AFM images. The intensity of the (002) plane of the X-ray diffraction pattern showed a significant difference depending on the deposition conditions of the thin films formed by O2 and Ar atmosphere gas types. In the case of a single thin f ilm doped with Ga under O2 conditions, a strong diffraction peak was observed. Under O2 and Ar conditions, in the case of a multilayer thin film with Ga doping, only a peak on the (002) plane with a somewhat weak intensity was shown. In the FE-SEM image, it was observed that the grain size of the surface of the thin film slightly increased as the thickness increased. In the case of a multilayer thin film with Ga doping under O2 and Ar atmosphere conditions, the specific resistance was 6.4 × 10-4 Ω·cm. In the case of a single thin film with Ga doping under O2 atmosphere conditions, the resistance of the thin film decreased. The resistance decreased as the thickness of the Ga-doped ZnO thin film increased to 2 ㎛, showing relatively a low specific resistance of 1.0 × 10-3 Ω·cm.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.291.2-291.2
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• 2013

Growth behavior of b-Ga2O3 nanowires (NWs) on sapphire(0001) substrates during radio-frequency magnetron sputtering is reported. Upon fabrication, flat thin films grew initially, subsequent to which, NW bundles were formed on the surface of thin film with increasing film thickness. This transition of the growth mode occurred only at temperatures greater than ${\sim}450^{\circ}C$. The b-Ga2O3 NWs were grown through the self-catalytic vapor-liquid-solid mechanism with self-assembled Ga seeds. Secondary growth of NWs, which occurred from the sides of primary NWs resulting in branched NW structures, was also observed. Finally, the room temperature photoluminescence properties of as-grown and annealed b-Ga2O3 NW samples were investigated.