• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 한국표면공학회 2016년도 추계학술대회 논문집
• /
• pp.188-188
• /
• 2016

GZO 박막은 상업적으로 사용되는 ITO를 경제적으로 대체할 수 있는 유망한 투명 전도 물질이며, 인체에 무해하고, 공급이 쉬우며, 화학적으로 안정하다. 특히, CIGS와 같은 광전변환 소자 전극에서는 부식 저항이 매우 중요한데, 습한 환경에서 견뎌낼 수 있다는 장점이 있다. GZO는 3가 갈륨이 2가 아연에 도핑된 n타입의 반도체 물질이다. 그리고 육각형의 황화아연 물질의 전기 전도도는 산소 결핍에 매우 의존한다. GZO의 수소는 산소 결핍 집중에 영향을 끼친다. 따라서 이 연구에서는 RF 마그네트론 스퍼터링 실험 동안 수소 함유량을 다양화 시키고, 면 저항, 광 투과도, 부식저항의 효과를 조사한다. 수소량이 증가할수록, 면 저항은 향상되어지고, 특정 지점을 넘으면 감소한다. 분극 실험에 의해 측정되어진 부식 저항은 박막의 미세조직과 결정립계의 특성에 더 의존되어진다. 훨씬 더 많은 수소를 함량한 비정질이 부식 저항성에 있어서 유효한 차이를 나타내지 못하는 동안 결정 내에서 많은 수소를 지닌 작은 결정의 결정립계는 낮은 분극저항, 즉 낮은 부식 저항성의 결과를 도출한다.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 한국재료학회 2011년도 추계학술발표대회
• /
• pp.43.1-43.1
• /
• 2011

Hydrogenated amorphous Si (a-Si:H), low temperature poly Si (LTPS) 등 기존 thin film transistors (TFTs)에 사용되던 채널 물질을 대체할 재료로써 다양한 연구가 진행되고 있는 amorphous indium-gallium-zinc-oxide (a-IGZO)는 TFT에 적용하였을 때 뛰어난 전기적 특성과 재연성을 나타낼 뿐만 아니라 넓은 밴드갭을 가져 투명소자로도 응용이 가능하다. 본 연구에서는 a-IGZO의 열처리에 따른 소자의 전기적 특성과 조성 분포의 관계를 확인하기 위해 다음과 같이 실험을 진행하였다. Si/SiO2 기판 위에 DC sputter를 이용하여 IGZO를 증착하고 $350^{\circ}C$에서 열처리를 한 후 evaporator로 Al 전극을 형성시켰다. 이 때 전기적 특성의 변화를 비교하기 위해 열처리 한 샘플과 열처리 하지 않은 샘플에 대해 I-V 특성을 측정하였고, 채널 내부의 조성 분포 변화를 transmission electron microscopy (TEM)의 energy dispersive spectrometer (EDS)를 이용하여 관찰하였다. 그 결과 열처리 된 a-IGZO 채널 층의 산소 비율이 감소하였으며 전체적인 조성이 고르게 분포 되었고 전기적 특성은 향상되었다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• 제65권10호
• /
• pp.1664-1671
• /
• 2016

This paper presents the analysis of the gate-source voltage of the gallium nitride high electronic mobility transistor (GaN HEMT) in the half bridge structure focused on the mutual effects of two switching operation. Especially low side gate-source voltage is analyzed mathematically according to the high side switch turn-on and turn-off operation. Moreover, the influence of each gate resistance and parasitic component on the switching characteristic of other side switch is investigated, and the formula, simulation and experimental results are compared with theoretical data.

• Journal of Power Electronics
• /
• 제15권6호
• /
• pp.1489-1498
• /
• 2015

Gallium nitride (GaN)-based power switching devices, such as high-electron-mobility transistors (HEMT), provide significant performance improvements in terms of faster switching speed, zero reverse recovery, and lower on-state resistance compared with conventional silicon (Si) metal-oxide-semiconductor field-effect transistors (MOSFET). These benefits of GaN HEMTs further lead to low loss, high switching frequency, and high power density converters. Through simulation and experimentation, this research thoroughly contributes to the understanding of performance characterization including the efficiency, loss distribution, and thermal behavior of a 160-W GaN-based synchronous boost converter under various output voltage, load current, and switching frequency operations, as compared with the state-of-the-art Si technology. Original suggestions on design considerations to optimize the GaN converter performance are also provided.

• Korean Journal of Materials Research
• /
• 제12권6호
• /
• pp.476-481
• /
• 2002

In this work, we report on the synthesis of the GaN powders from gallium oxide hydroxide (GaOOH) powders and on the structural and optical properties of them. Simple heat treatment of GaOOH in the flow of $NH_3$ gas leads to the formation of submicron hexagonal GaN powders even at the low reaction temperature of $800^{\circ}C$. XRD measurements show that the powders obtained are the single phase GaN. EDS, FTIR, and PL measurements indicate the oxygen-associated characteristics. It is shown from the low temperature PL measurement on GaN powders synthesized at $1000^{\circ}C$ that the shallow donor-acceptor recombination induced emission is more intense than the near band-edge excitonic emission.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.5-5
• /
• 2010

Gallium Nitride(GaN)는 LED, Laser 등에 사용되는 광학적 특성뿐만 아니라 Wide Bandgap의 전기적 특성 또한 주목받고 있다. 본 논문은 600V급 GaN(Gallium Nitride) Power SIT(Static Induction Transistor)에 대해서 Design Parameter 변환에 따른 전기적 (Breakdown Voltgage, On-state Voltage Drop)특성과 열적 (Lattice Temperature Distribution)특성변화를 분석하여 소자가 갖는 구조적 손실을 최소화하였다. 또한, 기존 실리콘 기반 전력소자와 특성 비교를 통하여 GaN Power SIT의 우수성을 증명하였다. GaN Power SIT 소자 설계 및 최적화를 위해서 Silvaco사의 소자 시뮬레이터인 ATLAS를 사용하였다. 실험 결과 수 ${\mu}m$의 소자 두께만으로도 실리콘 전력소자에 비해 더 뛰어난 열 특성과 더 적은 전력소모를 갖는 600V급 GaN Power SIT 소자를 구현할 수 있었다.

• Transactions on Electrical and Electronic Materials
• /
• 제18권6호
• /
• pp.323-329
• /
• 2017

This reports the electrical behavior, bonding structure and Schottky contact of gallium-zinc-oxide (GZO) thin film annealed at $100{\sim}400^{\circ}C$. The mobility of GZO with high density of PL spectra and crystal structure was also increased because of the structural matching between GZO and Si substrate of a crystal structure. However, the GZO annealed at $200^{\circ}C$ with an amorphous structure had the highest mobility as a result of a band to band tunneling effect. The mobility of GZO treated at low annealing temperatures under $200^{\circ}C$ increased at the GZO with an amorphous structure, but that at high temperatures over $200^{\circ}C$ also increased when it was the GZO of a crystal structure. The mobility of GZO with a Schottky barrier (SB) was mostly increased because of the effect of surface currents as well as the additional internal potential difference.

• Korean Journal of Materials Research
• /
• 제26권1호
• /
• pp.42-46
• /
• 2016

The properties of zinc oxynitride semiconductors and their associated thin film transistors are studied. Reactively sputtered zinc oxynitride films exhibit n-type conduction, and nitrogen-rich compositions result in relatively high electron mobility. Nitrogen vacancies are anticipated to act as shallow electron donors, as their calculated formation energy is lowest among the possible types of point defects. The carrier density can be reduced by substituting zinc with metals such as gallium or aluminum, which form stronger bonds with nitrogen than zinc does. The electrical properties of gallium-doped zinc oxynitride thin films and their respective devices demonstrate the carrier suppression effect accordingly.

• Journal of Information Display
• /
• 제10권4호
• /
• pp.171-174
• /
• 2009

The optical and electrical properties of the amorphous indium gallium zinc oxide thin-film transistor ($\alpha$-IGZO TFT) were studied. When the $\alpha$-IGZO TFT was illuminated at a wavelength of 660 nm, the off-state drain current slightly increased, while below 550 nm it increased significantly. The $\alpha$-IGZO TFT was found to be extremely sensitive, with deep-level defects at approximately 2.25 eV near the midgap. After UV light illumination, a slight change occurred on the surface of the $\alpha$-IGZO films, such as in terms of the oxygen 1s spectra, resistivity, and carrier concentrations. It is believed that these results will provide information regarding the photo-induced behaviors in the $\alpha$-IGZO films.

• The Korean Journal of Nuclear Medicine
• /
• 제21권1호
• /
• pp.83-88
• /
• 1987

$^{67}Ga$ Scanning may be a useful adjuvant in screening for suspected extrapulmonary tuberculosis and in assessing the response of therapy. A 52-year-old man with renal tuberculosis showed a renal localization of $^{67}Ga-citrate$ scans. Follow-up Scans after 3 months of chemotherapy showed decrease in uptake. So we present a case with the brief review of literatures.