• Title/Summary/Keyword: Dielectric Film

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Mechanical Property Evaluation of Dielectric Thin Films for Flexible Displays using Organic Nano-Support-Layer (유기 나노 보강층을 활용한 유연 디스플레이용 절연막의 기계적 물성 평가)

  • Oh, Seung Jin;Ma, Boo Soo;Yang, Chanhee;Song, Myoung;Kim, Taek-Soo
    • Journal of the Microelectronics and Packaging Society
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    • v.28 no.3
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    • pp.33-38
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    • 2021
  • Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiNx thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiNx thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiNx thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiNx thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiNx thin films fabricated through the same deposition condition increased compared to the ~130 nm SiNx thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.

Characteristics of Sn-doped β-Ga2O3 single crystals grown by EFG method (EFG 법으로 성장한 β-Ga2O3 단결정의 Sn 도핑 특성 연구)

  • Tae-Wan Je;Su-Bin Park;Hui-Yeon Jang;Su-Min Choi;Mi-Seon Park;Yeon-Suk Jang;Won-Jae Lee;Yun-Gon Moon;Jin-Ki Kang;Yun-Ji Shin;Si-Yong Bae
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.33 no.2
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    • pp.83-90
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    • 2023
  • The β-Ga2O3 has the most thermodynamically stable phase, a wide band gap of 4.8~4.9 eV and a high dielectric breakdown voltage of 8MV/cm. Due to such excellent electrical characteristics, this material as a power device material has been attracted much attention. Furthermore, the β-Ga2O3 has easy liquid phase growth method unlike materials such as SiC and GaN. However, since the grown pure β-Ga2O3 single crystal requires the intentionally controlled doping due to a low conductivity to be applied to a power device, the research on doping in β-Ga2O3 single crystal is definitely important. In this study, various source powders of un-doped, Sn 0.05 mol%, Sn 0.1 mol%, Sn 1.5 mol%, Sn 2 mol%, Sn 3 mol%-doped Ga2O3 were prepared by adding different mole ratios of SnO2 powder to Ga2O3 powder, and β-Ga2O3 single crystals were grown by using an edge-defined Film-fed Growth (EFG) method. The crystal direction, crystal quality, optical, and electrical properties of the grown β-Ga2O3 single crystal were analyzed according to the Sn dopant content, and the property variation of β-Ga2O3 single crystal according to the Sn doping were extensively investigated.

Structural and optical properties of Ni-substituted spinel $LiMn_2O_4$ thin films (니켈 치환된 스피넬 LiMn2O4 박막의 구조적, 광학적 성질)

  • Lee, Jung-Han;Kim, Kwang-Joo
    • Journal of the Korean Vacuum Society
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    • v.15 no.5
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    • pp.527-533
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    • 2006
  • Spinel $LiNi_xMn_{2-x}O_4$ thin films were synthesized up to x = 0.9 by a sol-gel method employing spin-coating. The Ni-substituted films were found to maintain cubic structure at low x but to exhibit tetragonal structure for $x{\geq}0.6$. Such cubic-tetragonal phase transition indicates that $Ni^{3+}(d7)$ ions with low-spin $(t_{2g}^6,e_g^1)$ state occupy the octahedral sites of the compound, thus being subject to the Jahn-Teller distortion. By x-ray photoelectron spectroscopy both $Ni^{2+}$ and $Ni^{3+}$ ions were detected. Optical properties of the $LiNi_xMn_{2-x}O_4$ films were investigated by spectroscopic ellipsometry (SE) in the visible?ultraviolet range. The measured dielectric function spectra by SE mainly consist of broad absorption structures attributed to charge-transfer (CT) transitions, $O^{2-}(2p){\rightarrow}Mn^{4+}(3d)$ for 1.9 $(t_{2g})$ and $2.8{\sim}3.0$ eV $(e_g)$ structures and $O^{2-}(2p){\rightarrow}Mn^{3+}(3d)$ for 2.3 $(t_{2g})$ and $3.4{\sim}3.6$ eV $(e_g)$ structures. Also, sharp absorption structures were observed at about 1.6, 1.7, and 1.9 eV, interpreted as due to d-d crystal-field transitions within the octahedral $Mn^{3+}$ ion. The strengths of these absorption structures are reduced by the Ni substitution. Rapid reduction of the CT transition strength involving the eg states for x = 0.6 is attributed to the reduced wavefunction overlap between the $e_g$ and the $O^{2-}(2p)$ states due to the tetragonal extension of the lattice constant by the Jahn-Teller effect.