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Article

Stabilizing of Mechanical Property of Amorphous In−Zn−O Thin Films with Hydrogen Flow

by
Seo-han Kim
1,
Janghee Yoon
2,
Sung-Ho Jin
3,
Joonho Bang
4,* and
Pungkeun Song
1,*
1
Department of Materials Science and Engineering, Pusan National University, Busandaehakro 63-2, Busan 46241, Korea
2
Busan Center, Korea Basic Science Institute, Busan 618-230, Korea
3
Department of Chemistry Education, Graduate Department of Chemical Materials, Institute for Plastic Information and Energy Materials, Pusan National university, Busandaehakro 63-2, Busan 46241, Korea
4
Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 26-8503, Japan
*
Authors to whom correspondence should be addressed.
Coatings 2019, 9(8), 485; https://doi.org/10.3390/coatings9080485
Submission received: 25 June 2019 / Revised: 24 July 2019 / Accepted: 30 July 2019 / Published: 31 July 2019
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Abstract

:
Amorphous In−Zn−O thin films were deposited with various hydrogen flow rates using a magnetron sputtering system. With the addition of hydrogen, the mechanical stability of the films was dramatically improved without any degradation of electrical properties and optical transmittance. The average change in the resistance of the sample deposited at a hydrogen flow rate of 0.4% was approximately six times lower than that in the sample deposited without hydrogen. Both, the compressive residual stress and absorption coefficient of the sample, decreased with hydrogen flow, indicating similar trends with the average change in the resistance. The absorption coefficient near 3.1 eV indicated that subgap state defects also decreased with increasing hydrogen flow rates. It was confirmed that the improvement in mechanical stability was derived from the suppression of subgap defects due to the hydrogen impurity. Thus, we demonstrated that hydrogen is a promising candidate for stabilizing the mechanical properties of oxide thin films.

1. Introduction

Recently, transparent electrodes (TEs) have assumed importance of the development of displays and electronic devices. TEs have been studied extensively owing to their high transmittance and electrical properties in the visible region [1,2,3]. There are various kinds of TEs, such as graphene, Ag nanowires, transparent conductive oxides (TCOs), and metal meshes. Among them, TCOs have been widely studied and employed in electronic devices such as organic light-emitting diodes (OLEDs), liquid crystal displays (LCDs), and touch screen panels (TSPs), because of their excellent optical and electrical properties [4,5,6,7,8]. Nowadays, with the increasing demand for flexible electronics, the issue with the mechanical stability of TCOs is attracting immense attention [5,9,10]. Mechanical stability under long-term bending stress is vital in flexible electrodes; however, studies on the stability are still lacking.
There have been many attempts to improve the mechanical properties of TCOs, using dopants, heat treatment, and amorphization [6,11,12,13,14,15]. Microcracks, which deteriorate the mechanical properties of polycrystalline structure, mainly depend on the grain boundary that generate microcracks that comes from defects [16,17,18,19].
Therefore, polycrystalline TCOs such as c-In−Sn−O, c-Al−Zn−O, and c-Ga−Zn−O are not suitable for flexible devices as TEs due to the grain boundary which generates microcracks that are harmful to the mechanical properties despite their high conductivity and optical transmittance [4,11,20,21]. Consequently, amorphous TCOs such as a-In−Sn−O, a-In−Zn−O, and a-In−Sn−Zn−O have been studied for flexible devices with high mechanical stability and comparable electrical and optical properties to those of polycrystalline TCOs [12,22,23,24,25,26].
In previous study, we found the hydrogen introduction induces the improvement of the mechanical stability of a-In−Sn−O [12]. However, there is fatal problem that the region which In−Sn−O could be a stable amorphous state; it can be easily crystallized during device fabrication process. In contrast, In−Zn−O can maintain a stable amorphous state at higher temperatures about 500 °C. For these reasons, we focus on the amorphous In−Zn−O (a-IZO) owing to its excellent etchability, high crystallization temperature, and high electrical and optical properties that are comparable to those of c-In−Sn−O [25,27,28]. The a-IZO has stable electrical and optical properties in the amorphous form; these properties are maintained up to a crystallization temperature [25]. Despite the higher mechanical stability of a-IZO, the mechanical stability of a-IZO needs improvement. To this end, many kinds of dopants such as heavy or alkali elements have been doped in IZO, such as W, Zr, Ga, Ni, Li, Na, and K [4,13,14,27,28].
Recent studies have clarified its crucial role in the physical properties of oxide semiconductors [12,29,30,31]. In this study, we demonstrate the effect of hydrogen flow during sputtering on the mechanical properties of a-IZO thin films. If the hydrogen could suppress defects as within In−Sn−O, it could be a good candidate as a universal defect healer for In2O3 based TCOs applied for flexible devices. For flexible applications, it is important to understand the role of hydrogen in oxide semiconductors. We believe that the mechanical stability could be improved by introducing an appropriate amount of hydrogen during sputtering, as the hydrogen may act as a defect healer by providing a hydrogen passivation effect, which is analogous to that observed for amorphous silicon [32,33]. As a result, we confirmed that the mechanical stability of a-IZO thin films with hydrogen is dramatically improved by adding an appropriate amount of hydrogen, without any observable degradation in the electrical and optical properties.

2. Experimental Details

First, 150 nm thick In−Zn−O thin films were deposited on a polyethylene terephthalate (PET) substrate (50 by 50 mm2, t = 250 μm) using a conventional DC magnetron sputtering system with a single sintered IZO target (In2O3:ZnO = 90:10 wt.%, dia. 3 in., 5 mm t). The thin films were deposited without intensive heating using a mixed gas of Ar and H2 at a total gas pressure of 0.7 Pa. The gas flow ratio of H2/(Ar + H2) was varied 0%, 0.1%, 0.2%, 0.4% and 0.8% under a constant total gas rate of 20 sccm. The distance between the substrate and target was 70 mm, and a power of 110 W (2.7 W/cm2) was applied to the sputtering target.
The films were approximately 150 nm thick, as confirmed using a spectral reflectometer (ST2000-DLXn, K-MAC, Daejeon, Korea). The crystal structures were determined by X-ray diffraction (XRD, Cu Kα, HADDS, BRUKER, Billerica, MA, USA). The electrical and optical properties were measured by Hall effect measurements (HMS-3000, ECOPIA, Anyang, Korea) and with a UV-visible spectrometer (SHIMADZU, UV-1800, Kyoto, Japan), respectively.
The dynamic bending properties of the thin films were estimated by measuring the change in resistance during the cyclic bending test with a digital multimeter (Agilent 34401A, Santa Rosa, CA, USA). The cyclic tests were performed on a rectangular sample with IZO thin films deposited on a PET substrate of size 10 by 40 mm2 (t = 250 μm). The frequency of bending was 0.5 Hz with constant linear vertical movements, and the bending radius (r) was 5 mm. The cracks formed on the surface of the thin film were observed using optical microscopy (BX41M, Olympus, Tokyo, Japan).
The residual stress of the thin films was estimated by a residual stress test (Residual stress tester, J&L Tech, Ansan, Korea) using a 300 μm thick Si substrate of size 5 by 50 mm2. The residual stress was estimated as follows Stoney Equation [34]:
σ = E s h 2 2 6 R h 1 ( 1 − v S )
where, ES is the Young’s elastic modulus and h1 and h2 represents the thickness of thin film and substrate, respectively. R denotes curvature of sample and vs is Poisson’s ratio of the substrate. The elastic modulus of Si substrate and the thickness of thin films were used to estimate the residual stresses.

3. Results and Discussion

Figure 1 represents the XRD patterns of the IZO thin films deposited with hydrogen flow rates from 0.0% to 0.8% during sputtering processes. Every sample showed amorphous structure; the crystallization temperature of IZO thin film is almost 600 °C.
The electrical properties of the a-IZO thin films are presented in Figure 2. The electrical properties of IZO thin films could be affected by hydrogen; the hydrogen easily changed chemical state and they attribute to carrier density [12,30]. However, the resistivity, carrier density, and mobility does not show observable change with various hydrogen flow rates and the values were similar with previous study [12]. As shown in Figure 2, there are no significant differences in the carrier density and Hall mobility. Therefore, it is conjectured that hydrogen might form a deep energy level in a-IZO thin films.
A dynamic bending test was conducted to evaluate the mechanical property of the a-IZO thin films. Figure 3a shows the changes in resistance (∆R/R0, where R0 is the initial resistance) under dynamic bending with increasing cycles, and Figure 3b shows the surface images of the cracks generated on the thin film after the bending tests. Figure 3c,d shows the surface of the IZO films deposited without hydrogen after the dynamic bending test, and that deposited with a H2 flow rate of 0.4%. Figure 3e shows a magnified view of the cracks. The IZO thin film deposited without hydrogen flow showed dramatic changes in resistance with increasing number of cycles and many microcracks were observed on the surface of the thin film after the bending test in Figure 3c,d. On the other hand, with increasing hydrogen flow rates, the changes in resistance drastically decreased until a hydrogen flow rate of 0.4% [H2/(Ar + H2)] and increased again at higher hydrogen flow rates. The number of microcracks generated on the surface of the thin film exhibited a similar trend to the changes in resistance. There are distinct differences in the number of cracks, as observed in Figure 3c,d. These results indicate that there exists a relationship between the change in the resistance and number of microcracks; this is because microcracks may serve as barriers to electron conduction, thereby increasing the electrical resistivity.
Figure 4a,b shows the average changes in resistance during the dynamic bending tests and residual stress of the IZO thin films deposited with various hydrogen flow rates. The average changes in the resistance of the IZO thin films are approximately 100 times lower than those previously reported for an ITO thin film [12]; this result seems reasonable considering that the more stable amorphous structure of a-IZO compared to that of a-ITO.
The average ∆R/R0 of the thin film deposited with a hydrogen flow rate of 0.4% was 1.09 × 10−5, which is six times lower than that of the film deposited without hydrogen flow. Figure 4b shows that the residual stress of the IZO thin films has negative values, indicating that the residual stress on the IZO thin films is a compressive stress. The trend for the residual stress is similar to that for the changes in resistance, suggesting that the residual stress is negligibly dependent on the mechanical stability.
Figure 5a shows the transmittance and Figure 5b absorption coefficient (α) of the IZO thin films deposited with various hydrogen flow rates. The absorption coefficient is estimated from the equation α = −ln(T/(1 − R))/d, where T and R are the transmittance and reflectance, and d is the film thickness. All thin films showed high transmittance near 550 nm (~80%), and there was no significant difference for the different hydrogen flow rates. However, there exists obvious difference in the absorption coefficient that IZO thin film deposited with hydrogen flow showed lower α compared to deposited without hydrogen flow and the IZO deposited with hydrogen flow rate 0.4 % showed the lowest α at 3.1 eV. The mechanical stability of the thin films depends on defects such as vacancies and impurities, which in turn affect the subgap state. Decrease in both, the residual stress and subgap absorption, is achieved by introducing hydrogen flow during the deposition, because hydrogen acts as a defect healer to suppress subgap state defects. Thus, appropriate hydrogen flow during deposition can improve the mechanical stability by suppressing the subgap state defects, to thereby decrease defects.

4. Conclusions

a-IZO films were prepared with various hydrogen flow rates during deposition using a magnetron sputtering system. The mechanical stability of the a-IZO thin films dramatically improved with appropriate hydrogen flow rates, without remarkable changes in the resistivity and transmittance. The average changes in resistance and residual stress dramatically decreased until a hydrogen flow rate of 0.4% and then increased again. The subgap absorption showed a similar trend with the residual stress. The subgap absorption near 3.1 eV was successfully suppressed with hydrogen flow. These results indicate that the hydrogen-terminated dangling bond in an amorphous structure behaves like the hydrogen in amorphous Si. This study demonstrates that an appropriate amount of hydrogen in thin films can effectively suppress subgap defects, thereby improving the mechanical stability.

Author Contributions

Conceptualization, S.K. and J.B.; Data curation, J.Y.; Formal analysis, J.Y.; Funding acquisition, P.S.; Investigation, S.K.; Supervision, P.S.; Writing—original draft, S.K.; Writing—review & editing, J.B. and P.S.

Funding

This work was funded by the National Research Foundation of Korea (NRF) grant (No. 2017R1A2B4012144 and No. 2018R1A5A1025594) and partially financially supported by the [2019 Post-Doc. Development Program] of Pusan National University.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Song, P.K.; Shigesato, Y.; Yasui, I.; Cleva, W.; Yang, W.O.; Paine, D.C. Study on Crystallinity of tin-doped Indium oxide films sputtering deposited by dc magnetron. Jpn. J. Appl. Phys. 1998, 37, 1870. [Google Scholar] [CrossRef]
  2. Kim, D.H.; Park, M.R.; Lee, G.H. Preparation of high quality ITO films on a plastic substrate using RF magnetron sputtering. Surf. Coat. Technol. 2006, 201, 927–931. [Google Scholar] [CrossRef]
  3. Sannicolo, T.; Lagrange, M.; Cabos, A.; Celle, C.; Simonato, J.P.; Bellet, D. Metallic Nanowire-Based Transparent Electrodes for Next Generation Flexible Devices: A Review. Small 2016, 12, 6052–6075. [Google Scholar] [CrossRef] [PubMed]
  4. Oh, B.Y.; Jeong, M.C.; Moon, T.H.; Lee, W.; Myoung, J.M.; Hwang, J.Y.; Seo, D.S. Transparent conductive Al-doped ZnO films for liquid crystal displays. J. Appl. Phys. 2006, 99, 124505. [Google Scholar] [CrossRef]
  5. Leterrier, Y.; Médico, L.; Demarco, F.; Månson, J.A.E.; Betz, U.; Escolà, M.F.; Olsson, M.K.; Atamny, F. Mechanical integrity of transparent conductive oxide films for flexible polymer-based displays. Thin Solid Film 2004, 460, 156–166. [Google Scholar] [CrossRef]
  6. Kang, J.W.; Jeong, W.I.; Kim, J.J.; Kim, H.K.; Kim, D.G.; Lee, G.H. High-Performance Flexible Organic Light-Emitting Diodes Using Amorphous Indium Zinc Oxide Anode. Electrochem. Solid-State Lett. 2007, 10, J75–J78. [Google Scholar] [CrossRef]
  7. Hwang, T.H.; Cui, W.H.; Yang, I.S.; Kwon, O.K. A highly area-efficient controller for capacitive touch screen panel systems. IEEE Trans. Consum. Electron. 2010, 56, 1115–1122. [Google Scholar] [CrossRef]
  8. Lee, J.; Han, T.H.; Park, M.H.; Jung, D.Y.; Seo, J.; Seo, H.K.; Cho, H.; Kim, E.; Chung, J.; Choi, S.Y.; et al. Synergetic electrode architecture for efficient graphene-based flexible organic light-emitting diodes. Nat. Commun. 2016, 7, 1–9. [Google Scholar] [CrossRef]
  9. Mohl, M.; Dombovari, A.; Vajtai, R.; Ajayan, P.M.; Kordas, K. Self-assembled large scale metal alloy grid patterns as flexible transparent conductive layers. Sci. Rep. 2015, 5, 1–8. [Google Scholar] [CrossRef]
  10. Sahu, B.B.; Long, W.; Han, J.G. Highly conductive flexible ultra thin ITO nanoclusters prepared by 3-D confined magnetron sputtering at a low temperature. Scr. Mater. 2018, 149, 98–102. [Google Scholar] [CrossRef]
  11. Kim, M.J.; Song, P.K. High Crystallization of Ultra-Thin Indium Tin Oxide Films Prepared by Direct Current Magnetron Sputtering with Post-Annealing. Sci. Adv. Mater. 2016, 8, 622. [Google Scholar] [CrossRef]
  12. Kim, S.; Yoon, J.h.; Bang, J.; Song, P. Effect of hydrogen on mechanical stability of amorphous In–Sn–O thin films for flexible electronics. Thin Solid Films 2019, 669, 275–280. [Google Scholar] [CrossRef]
  13. Lee, Y.-J.; Lim, B.-W.; Kim, J.-H.; Kim, T.-W.; Oh, B.Y.; Heo, G.-S.; Kim, K.-Y. Thin Transparent W-Doped Indium-Zinc Oxide (WIZO) layer on glass. J. Nanosci. Nanotechnol. 2012, 12, 5604–5608. [Google Scholar] [CrossRef] [PubMed]
  14. Choi, K.-H.; Jeong, J.-A.; Kim, H.-K.; Lee, J.-Y.; Lee, J.-H.; Bae, H.-D.; Tak, Y.-H.; Lee, S.-H.; Leem, D.-S.; Kim, J.-J. Characteristics of Ni-Doped IZO Layers grown on izo anode for enhancing hole injection in OLEDs. J. Electrochem. Soc. 2008, 155, J340–J344. [Google Scholar] [CrossRef]
  15. Zhang, Q.; Di, Y.; Huard, C.M.; Guo, L.J.; Wei, J.; Guo, J. Highly stable and stretchable graphene-polymer processed silver nanowires hybrid electrodes for flexible displays. J. Mater. Chem. C 2015, 3, 1528–1536. [Google Scholar] [CrossRef]
  16. Alzoubi, K.; Hamasha, M.M.; Lu, S.; Sammakia, B. Bending fatigue study of sputtered ITO on flexible substrate. J. Display Techn. 2011, 7, 593–600. [Google Scholar] [CrossRef]
  17. Ohya, Y.; Nakaoawa, Z. Grain-boundary microcracking due to thermal expansion anisotropy in aluminum titanate ceramics. J. Am. Ceram. Soc. 1987, 70, 184–186. [Google Scholar] [CrossRef]
  18. Ohya, Y.; Nakagawa, Z. Crack healing and bending strength of aluminum titanate ceramics at high temperature. J. Am. Ceram. Soc. 1998, 71, 232–233. [Google Scholar] [CrossRef]
  19. Lin, H.; Pope, D.P. The influence of grain boundary geometry on intergranular crack propagation in Ni3Al. Acta Metall. Mater. 1993, 41, 553–562. [Google Scholar]
  20. Fortunato, E.; Raniero, L.; Siva, L.; Gonçalves, A.; Pimentel, A.; Barquinha, P.; Águas, H.; Pereira, L.; Gonçalves, G.; Ferreira, I.; et al. Highly stable transparent and conducting gallium-doped zinc oxide thin films for photovoltaic applications. Sol. Energy Mater. Sol. Cells 2008, 92, 1605–1610. [Google Scholar] [CrossRef]
  21. Minami, T.; Nanto, H.; Takata, S. Highly Conductive and Transparent Aluminum Doped Zinc Oxide Thin Films Prepared by RF Magnetron Sputtering. Jap. J. Appl. Phys. 1984, 23, L280. [Google Scholar] [CrossRef]
  22. Kang, Y.M.; Kwon, S.H.; Choi, J.H.; Cho, Y.J.; Song, P.K. Properties of Ce-doped ITO films deposited on polymer substrate by DC magnetron sputtering. Thin Solid Films 2010, 518, 3081–3084. [Google Scholar] [CrossRef]
  23. Choi, S.R.; Cho, S.H.; Kim, S.I.; Kang, Y.M.; Yoon, H.H.; Kim, K.H.; Song, P.K. Microstructure and Electrical Properties of Yb- or Sm-Doped Indium–Tin-Oxide Films Prepared by DC Magnetron Sputtering. Jpn. J. Appl. Phys. 2009, 48, 05EC04. [Google Scholar] [CrossRef]
  24. Jeong, S.; Ha, Y.G.; Moon, J.; Facchetti, A.; Marks, T.J. Role of gallium doping in dramatically lowering amorphous-oxide processing temperatures for solution-derived indium zinc oxide thin-film transistor. Adv. Mater. 2010, 22, 1346–1350. [Google Scholar] [CrossRef] [PubMed]
  25. Hara, H.; Hanada, T.; Shiro, T.; Yatabe, T. Properties of indium zinc oxide thin films on heat withstanding plastic substrate. J. Vac. Sci. Technol. A Vac. Surf. Film 2004, 22, 1726. [Google Scholar] [CrossRef]
  26. Ni, J.; Yan, H.; Wang, A.; Yang, Y.; Stern, C.L.; Metz, A.W.; Jin, S.; Wang, L.; Marks, T.J.; Ireland, J.R.; et al. MOCVD-derived highly transparent, conductive zinc- and tin-doped indium oxide thin films: Precursor synthesis, metastable phase film growth and characterization, and application as anodes in polymer light-emitting diodes. J. Am. Chem. Soc. 2005, 127, 5613–5624. [Google Scholar] [CrossRef] [PubMed]
  27. Choi, W.S.; Jo, H.; Kwon, M.S.; Jung, B.J. Control of electrical properties and gate bias stress stability in solution-processed a-IZO TFTs by Zr doping. Curr. Appl. Phys. 2014, 14, 1831–1836. [Google Scholar]
  28. Wan, D.; Liu, X.; Xu, L.; Liu, C.; Xiao, X.; Guo, S.; Liao, L. The Study for Solution-Processed Alkali Metal-Doped Indium-Zinc Oxide Thin-Film Transistors. IEEE Electron Device Lett. 2016, 37, 50–52. [Google Scholar] [CrossRef]
  29. Byeon, J.; Kim, S.; Lim, J.H.; Song, J.Y.; Park, S.H.; Song, P. Thermoelectric and electrical properties of micro-quantity Sn-doped amorphous indium-zinc oxide thin films. Jpn. J. Appl. Phys. 2017, 56, 010304. [Google Scholar] [CrossRef]
  30. Bang, J.; Matsuishi, S.; Hosono, H. Hydrogen anion and subgap states in amorphous In-Ga-Zn-O thin films for TFT applications. Appl. Phys. Lett. 2017, 110, 232105. [Google Scholar] [CrossRef]
  31. Walle, C.V.D. Hydrogen as a cause of doping in zinc oxide. Phys. Rev. Lett. 2000, 85, 1012–1015. [Google Scholar] [CrossRef] [PubMed]
  32. Assali, L.V.C.; Leite, J.R. Microscopic mechanism of hydrogen passivation of acceptor shallow levels in silicon. Phys. Rev. Lett. 1985, 55, 980–982. [Google Scholar] [CrossRef] [PubMed]
  33. Stutzmann, M. The defect density in amorphous silicon. Philos. Mag. B 1989, 60, 531–546. [Google Scholar] [CrossRef]
  34. He, C.R.; Wang, W.G.; Wang, J.; Xue, Y. Effect of alumina on the curvature, Young’s modulus, thermal expansion coefficient and residual stress of planar solid oxide fuel cells. J. Power Sources 2011, 196, 7639–7644. [Google Scholar] [CrossRef]
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Figure 1. XRD patterns of In−Zn−O thin films deposited with various hydrogen flow rates.
Figure 1. XRD patterns of In−Zn−O thin films deposited with various hydrogen flow rates.
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Figure 2. Electrical properties of In−Zn−O thin films as a function of hydrogen flow rates.
Figure 2. Electrical properties of In−Zn−O thin films as a function of hydrogen flow rates.
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Figure 3. Dynamic bending test results for In−Zn−O thin films prepared with various hydrogen flow rates. (a) changes in resistance (ΔR/R0) with the bending cycle and (b) corresponding surface images after bending tests. (c) and (d) are surface crack images after dynamic bending of a-IZO thin film deposited without, with hydrogen flow and the enlarged surface crack, respectively.
Figure 3. Dynamic bending test results for In−Zn−O thin films prepared with various hydrogen flow rates. (a) changes in resistance (ΔR/R0) with the bending cycle and (b) corresponding surface images after bending tests. (c) and (d) are surface crack images after dynamic bending of a-IZO thin film deposited without, with hydrogen flow and the enlarged surface crack, respectively.
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Figure 4. Mechanical properties of In−Zn−O thin films as a function of various hydrogen flow rates. (a) average changes in resistance (ΔR/R0) and (b) residual stress of In−Zn−O thin films.
Figure 4. Mechanical properties of In−Zn−O thin films as a function of various hydrogen flow rates. (a) average changes in resistance (ΔR/R0) and (b) residual stress of In−Zn−O thin films.
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Figure 5. Optical properties of In−Zn−O thin films with various hydrogen flow rates. (a) transmittance and (b) absorption coefficients (α) calculated from the measured transmittance and reflectance spectra, respectively.
Figure 5. Optical properties of In−Zn−O thin films with various hydrogen flow rates. (a) transmittance and (b) absorption coefficients (α) calculated from the measured transmittance and reflectance spectra, respectively.
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MDPI and ACS Style

Kim, S.-h.; Yoon, J.; Jin, S.-H.; Bang, J.; Song, P. Stabilizing of Mechanical Property of Amorphous In−Zn−O Thin Films with Hydrogen Flow. Coatings 2019, 9, 485. https://doi.org/10.3390/coatings9080485

AMA Style

Kim S-h, Yoon J, Jin S-H, Bang J, Song P. Stabilizing of Mechanical Property of Amorphous In−Zn−O Thin Films with Hydrogen Flow. Coatings. 2019; 9(8):485. https://doi.org/10.3390/coatings9080485

Chicago/Turabian Style

Kim, Seo-han, Janghee Yoon, Sung-Ho Jin, Joonho Bang, and Pungkeun Song. 2019. "Stabilizing of Mechanical Property of Amorphous In−Zn−O Thin Films with Hydrogen Flow" Coatings 9, no. 8: 485. https://doi.org/10.3390/coatings9080485

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