• Title/Summary/Keyword: GaInZnO

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A study on transparent conducting films for GaN-based light emitting diodes (GaN-LED용 투명전도막에 대한 연구)

  • Lee, Kang-Young;Kim, Won;Uhm, Hyun-Seok;Kim, Eun-Kyu;Kim, Myun-Sung;Park, Jin-Seok
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1270-1271
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    • 2008
  • Effects of thin ZnO/Mg interlayers on electrical and optical properties between p-GaN and ITO were characterized for its application to GaN-LEDs. The ZnO and Mg layers were deposited to have various thicknesses (1${\sim}$6nm for ZnO and 1${\sim}$2nm for Mg) by sputtering. After RTA process, the atomic migration between Mg and ZnO and the formation of Ga vacancy were observed from SIMS depth profile, resulting in the increase of hole concentration and the reduction of band bending at the surface region of p-GaN. The sample using ZnO(2nm)/Mg(2nm) interlayer produced the lowest contact resistance with SBH(Schottky barrier height) of 0.576 eV and the transmittance higher than 83% at a wavelength of 460nm when annealed at 500$^{\circ}C$ for 3min in air ambient.

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Optical Properties of a ZnO-MgZnO Quantum-Well

  • Ahn, Do-Yeol;Park, Seoung-Hwan
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.6 no.3
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    • pp.125-130
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    • 2006
  • The optical gain and the luminescence of a ZnO quantum well with MgZnO barriers is studied theoretically. We calculated the non-Markovian optical gain and the luminescence for the strained-layer wurtzite quantum well taking into account of the excitonic effects. It is predicted that both optical gain and luminescence are enhanced for the ZnO quantum well when compared with those of InGaN-AlGaN quantum well structure due to the significant reduction of the piezoelectric effects in the ZnO-MgZnO systems.

Characterization of Atomic-Layer Deposited ZnSnO Buffer Layer for 18%- Efficiency Cu(In,Ga)Se2 Solar Cells (18% 효율 Cu(In,Ga)Se2 박막태양전지용 ZnSnO 버퍼층의 원자층 증착법 및 분석)

  • Kim, Sun Cheul;Kim, Seung Tae;Ahn, Byung Tae
    • Current Photovoltaic Research
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    • v.3 no.2
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    • pp.54-60
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    • 2015
  • ZnSnO thin films were deposited by atomic layer deposition (ALD) process using diethyl zinc ($Zn(C_2H_5)_2$) and tetrakis (dimethylamino) tin ($Sn(C_2H_6N)_4$) as metal precursors and water vapor as a reactant. ALD process has several advantages over other deposition methods such as precise thickness control, good conformality, and good uniformity for large area. The composition of ZnSnO thin films was controlled by varying the ratio of ZnO and $SnO_2$ ALD cycles. The ALD ZnSnO film was an amorphous state. The band gap of ZnSnO thin films increased as the Sn content increased. The CIGS solar cell using ZnSnO buffer layer showed about 18% energy conversion efficiency. With such a high efficiency with the ALD ZnSnO buffer and no light soaking effect, AlD ZnSnO buffer mighty be a good candidate to replace Zn(S,O) buffer in CIGSsolar cells.

Effect of InGaZnO Solution Concentration on the Electrical Properties of Drop-Cast Oxide Thin-Film Transistors (InGaZnO 용액의 농도가 Drop-casting으로 제작된 산화물 박막 트랜지스터의 전기적 특성에 미치는 영향)

  • Noh, Eun-Kyung;Yu, Kyeong Min;Kim, Min-Hoi
    • Journal of Sensor Science and Technology
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    • v.29 no.5
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    • pp.332-335
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    • 2020
  • Drop casting, a solution process, is a simple low-cost fabrication technique that does not waste material. In this study, we elucidate the effect of the concentration of a InGaZnO solution on the electrical properties of drop-cast oxide thin-film transistors. The higher the concentration the larger the amount of remnant InGaZnO solutes, which yields a thicker thin film. Accordingly, the electrical properties were strongly dependent on the concentration. At a high concentration of 0.3 M (or higher), a large current flowed but did not lead to switching characteristics. At a concentration lower than 0.01 M, switching characteristics were observed, but the mobility was small. In addition to a high mobility, sufficient switching characteristics were obtained at a concentration of 0.1 M owing to the appropriate thickness of the semiconductor layer. This study provides a technical basis for the low-cost fabrication of switching devices capable of driving a sensor array.

Effect of Ga Dopants on Electrical and Optical Characteristics of ZnO Thin Films (Ga 첨가물이 ZnO의 전기적, 광학적 특성에 미치는 영향)

  • Kim, Jun-Sik;Jang, Gun-Eik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.9
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    • pp.685-690
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    • 2010
  • ZnO with the wide band gap near 3.37 eV is typically an n-type semiconductor in which deviation from stoichiometry is electrically active. It was known that the films with a resistivity of the order of $10^{-4}{\Omega}cm$ is not easy to obtain. In order to improve electrical characteristic of ZnO, we added 1, 3, 5 wt% Ga element in ZnO. The Ga-doped ZnO (GZO) was grown on a glass substrate by radio frequency (RF) magnetron sputtering at the temperature range from 100 to $500^{\circ}C$. X-ray diffraction (XRD) patterns of GZO films showed preferable crystal orientation of (002) plane. The lowest resistivity of the GZO films was $8.9{\times}10^{-4}{\Omega}cm$. GZO films significantly influenced by the working temperature. The average transmittance of the films was over 80% in the visible ranges.

A study on properties of ZnO:Ga thin films fabricated by RF Magnetron sputtering (RF Magnetron sputtering으로 증착한 ZnO:Ga의 특성에 관한 연구)

  • Kim, H.S.;Kim, K.B.;Koo, B.K.;Park, K.Y.;Koo, K.W.;Han, S.O.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.953-956
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    • 2003
  • Transparent conductive ZnO:Ga thin films were deposited on glass substrates using rf magnetron sputtering method for flat panel display. The ZnO:Ga films were preferentially oriented to c-axis (002) of on substrates. The surface morphology was smooth and had not porous whatever substrate temperature was. The electrical conductivity of the thin films were in the range of $1.6{\times}10^2{\sim}6.7{\times}10^3\;{\Omega}^{-1}cm^{-1}$ at the growth temperature from 50 to $400^{\circ}C$, whereas has a maximum at around $250^{\circ}C$. By combining of XRD and EXAFS, the crystallinity and grain size decreased with increasing substrate temperature corresponding to the reduction of the grain-boundary scattering. The optical transmittance of sputtered ZnO:Ga thin films had an improved about 86% in the UV-visible region.

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Effect of Process Variation of Al Grid and ZnO Transparent Electrode on the Performance of Cu(In,Ga)Se2 Solar Cells (Al 그리드와 ZnO 투명전도막 의 공정변화에 따른 Cu(In,Ga)Se2 박막태양전지의 특성 연구)

  • Cho, Bo Hwan;Kim, Seon Cheol;Mun, Sun Hong;Kim, Seung Tae;Ahn, Byung Tae
    • Current Photovoltaic Research
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    • v.3 no.1
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    • pp.32-38
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    • 2015
  • CIGS solar cell consisted of various films. In this research, we investigated electrode materials in $Cu(In,Ga)Se_2$ (CIGS) cells, including Al-doped ZnO (ZnO:Al), intrinsic ZnO (i-ZnO), and Al films. The sputtered ZnO:Al film with a sputtering power at 200W showed the lowest series resistance and highest cell efficiency. The electrical resistivity of the 200-W sputtered ZnO:Al film was $5.2{\times}10^{-4}{\Omega}{\cdot}cm$ by the rapid thermal annealing at $200^{\circ}C$ for 1 min. The electrical resistivity of i-ZnO was not measurable due to its high resistance. But the optical transmittance was highest with less oxygen supply and high efficiency cell was achieved with $O_2/(Ar+O_2)$ ratio was 1% due to the increase of short-circuit current. No significant change in the cell performance by inserting a Ni layer between Al and ZnO:Al films was observed.

RF Magentron Sputtering deposited by ZnO:Ga thin film characterization for a transparent thin film transistor an application (투명 박막 트랜지스터 응용을 위한 RF Magnetron Sputtering으로 증착된 ZnO:Ga 박막의 특성)

  • Lee, Seok-Jin;Kwon, Soon-Il;Park, Seung-Beum;Jung, Tae-Hwan;Lim, Dong-Gun;Park, Jea-Hwan;Yang, Kea-Joon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.146-147
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    • 2008
  • In this paper we report upon an investigation into the effect of sputter RF power on the electrical properties of Gallium doped zinc oxide (ZnO:Ga) film. Structural, electrical and optical properties of the ZnO:Ga films were investigation in terms of the sputtering power. Working pressure fixed in 5 mtorr and RF powers the variable did with 50~100 W. The result, We were able to without substrate temperature obtain resistivity of $9.3\times10^{-4}{\Omega}cm$ and optical transmittance of 90%.

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Highly Luminescent (Zn0.6Sr0.3Mg0.1)2Ga2S5:Eu2+ Green Phosphors for a White Light-Emitting Diode

  • Jeong, Yong-Kwang;Cho, Dong-Hee;Kim, Kwang-Bok;Kang, Jun-Gill
    • Bulletin of the Korean Chemical Society
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    • v.33 no.8
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    • pp.2523-2528
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    • 2012
  • Green phosphors $(Zn_{1-a-b}M_aM^{\prime}_b)_xGa_yS_{x+3y/2}:Eu^{2+}$ (M, M' = alkali earth ions) with x = 2 and y = 2-5 were prepared, starting from ZnO, MgO, $SrCO_3$, $Ga_2O_3$, $Eu_2O_3$, and S with a flux $NH_4F$ using a conventional solidstate reaction. A phosphor with the composition of $(Zn_{0.6}Sr_{0.3}Mg_{0.1})_2Ga_2S_5:Eu^{2+}$ produced the strongest luminescence at a 460-nm excitation. The observed XRD patterns indicated that the optimized phosphor consisted of two components: zinc thiogallate and zinc sulfide. The characteristic green luminescence of the $ZnS:Eu^{2+}$ component on excitation at 460 nm was attributed to the donor-acceptor ($D_{ZnGa_2S_4}-A_{ZnS}$) recombination in the hybrid boundary. The optimized green phosphor converted 17.9% of the absorbed blue light into luminescence. For the fabrication of light-emitting diode (LED), the optimized phosphor was coated with MgO using magnesium nitrate to overcome their weakness against moisture. The MgO-coated green phosphor was fabricated with a blue GaN LED, and the chromaticity index of the phosphor-cast LED (pc-LED) was investigated as a function of the wt % of the optimized phosphor. White LEDs were fabricated by pasting the optimized green (G) and the red (R) phosphors, and the commercial yellow (Y) phosphor on the blue chips. The three-band pc-WLED resulted in improved color rendering index (CRI) and corrected color temperature (CCT), compared with those of the two-band pc-WLED.

Thermal diffusion properties of Zn, Cd, S, and B at the interface of CuInGaSe2 solar cells

  • Yoon, Young-Gui;Choi, In-Hwan
    • Current Photovoltaic Research
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    • v.1 no.1
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    • pp.52-58
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    • 2013
  • Two different window-structured $CuInGaSe_2$(CIGS) solar cells, i.e., CIGS/thin-CdS/ZnO:B(sample A) and CIGS/very thin-CdS/Zn(S/O)/ZnO:B(sample B), were prepared, and the diffusivity of Zn, Cd, S, and B atoms, respectively, in the CIGS, ZnO or Zn(S/O) layer was estimated by a theoretical fit to experimental secondary ion mass spectrometer data. Diffusivities of Zn, Cd, S, and B atoms in CIGS were $2.0{\times}10^{-13}(1.5{\times}10^{-13})$, $4.6{\times}10^{-13}(4.4{\times}10^{-13})$, $1.6{\times}10^{-13}(1.8{\times}10^{-13})$, and $1.2{\times}10^{-12}cm^2/s$ at 423K, respectively, where the values in parentheses were obtained from sample B and the others from sample A. The diffusivity of the B atom in a Zn(S/O) of sample B was $2.1{\times}10^{-14}cm^2/sec$. Moreover, the diffusivities of Cd and S atoms diffusing back into ZnO(sample A) or Zn(S/O)(sample A) layers were extremely low at 423K, and the estimated diffusion coefficients were $2.2{\times}10^{-15}cm^2/s$ for Cd and $3.0{\times}10^{-15}cm^2/s$ for S.