Amorphous metal-oxide semiconductors have emerged as potential replacements for organic and silicon materials in thin-film electronics. The high carrier mobility in the amorphous state, and excellent large-area uniformity, have extended their applications to active-matrix electronics, including displays, sensor arrays and X-ray detectors1,2,3,4,5,6,7. Moreover, their solution processability and optical transparency have opened new horizons for low-cost printable and transparent electronics on plastic substrates8,9,10,11,12,13. But metal-oxide formation by the sol–gel route requires an annealing step at relatively high temperature2,14,15,16,17,18,19, which has prevented the incorporation of these materials with the polymer substrates used in high-performance flexible electronics. Here we report a general method for forming high-performance and operationally stable metal-oxide semiconductors at room temperature, by deep-ultraviolet photochemical activation of sol–gel films. Deep-ultraviolet irradiation induces efficient condensation and densification of oxide semiconducting films by photochemical activation at low temperature. This photochemical activation is applicable to numerous metal-oxide semiconductors, and the performance (in terms of transistor mobility and operational stability) of thin-film transistors fabricated by this route compares favourably with that of thin-film transistors based on thermally annealed materials. The field-effect mobilities of the photo-activated metal-oxide semiconductors are as high as 14 and 7 cm2 V−1 s−1 (with an Al2O3 gate insulator) on glass and polymer substrates, respectively; and seven-stage ring oscillators fabricated on polymer substrates operate with an oscillation frequency of more than 340 kHz, corresponding to a propagation delay of less than 210 nanoseconds per stage.
This is a preview of subscription content, access via your institution
Open Access articles citing this article.
Nature Communications Open Access 19 April 2022
One-step photonic curing of screen-printed conductive Ni flake electrodes for use in flexible electronics
Scientific Reports Open Access 09 February 2021
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Nomura, K. et al. Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors. Nature 432, 488–492 (2004)
Kim, M. G., Kanatzidis, M. G., Facchetti, A. & Marks, T. J. Low-temperature fabrication of high-performance metal oxide thin-film electronics via combustion processing. Nature Mater. 10, 382–388 (2011)
Facchetti, A. & Marks, T. J. Transparent Electronics (Wiley, 2010)
Dusastre, V. Materials for Sustainable Energy. (World Scientific, 2010)
Kamiya, T., Nomura, K. & Hosono, H. Present status of amorphous In-Ga-Zn-O thin-film transistors. Sci. Technol. Adv. Mater. 11, 044305 (2010)
Jeon, S. et al. Nanometer-scale oxide thin film transistor with potential for high-density image sensor applications. ACS Appl. Mater. Interfaces 3, 1–6 (2011)
Kim, K. M. et al. Competitive device performance of low-temperature and all-solution-processed metal-oxide thin-film transistors. Appl. Phys. Lett. 99, 242109 (2011)
Yang, S. et al. Low-temperature processed flexible In-Ga-Zn-O thin-film transistors exhibiting high electrical performance. Electron. Dev. Lett. 32, 1692–1694 (2011)
Wager, J. F. Transparent electronics. Science 300, 1245–1246 (2003)
Cao, Q. et al. Medium-scale carbon nanotube thin-film integrated circuits on flexible plastic substrates. Nature 454, 495–500 (2008)
Klauk, H. Organic Electronics: Materials, Manufacturing and Applications (Wiley-VCH, 2006)
Briseno, A. L. et al. Patterning organic single-crystal transistor arrays. Nature 444, 913–917 (2006)
Sekitani, T., Zschieschang, U., Klauk, H. & Someya, T. Flexible organic transistors and circuits with extreme bending stability. Nature Mater. 9, 1015–1022 (2010)
Han, S. Y., Herman, G. S. & Chang, C. Low-temperature, high-performance, solution-processed indium oxide thin-film transistors. J. Am. Chem. Soc. 133, 5166–5169 (2011)
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 transistors. Adv. Mater. 22, 1346–1350 (2010)
Meyers, S. T. et al. Aqueous inorganic inks for low-temperature fabrication of ZnO TFTs. J. Am. Chem. Soc. 130, 17603–17609 (2008)
Kim, Y. H., Han, J. I. & Park, S. K. Effect of Zn/Tin composition ratio on the operational stability of solution-processed zinc tin oxide thin film transistors. IEEE Electron Device Lett. 33, 50–52 (2012)
Kim, Y. H., Han, M. K., Han, J. I. & Park, S. K. Effect of metallic composition on electrical properties of solution-processed indium-gallium-zinc-oxide thin film transistors. IEEE Trans. Electron. Dev. 57, 1009–1014 (2010)
Adamopoulos, G. et al. High-mobility low-voltage ZnO and Li-doped ZnO transistors based on ZrO2 high-k dielectric grown by spray pyrolysis in ambient air. Adv. Mater. 23, 1894–1898 (2011)
Van de Leest, R. E. UV photo-annealing of thin sol-gel films. Appl. Surf. Sci. 86, 278–285 (1995)
Imai, H. in Handbook of Sol-Gel Science and Technology: Processing, Characterization and Applications Vol. 1 (ed. Sakka, S. ) 639–650 (Kluwer, 2005)
Clark, T., Jr et al. A new application of UV-ozone treatment in the preparation of substrate-supported, mesoporous thin films. Chem. Mater. 12, 3879–3884 (2000)
Imai, H., Tominaga, A., Hirashima, H., Toki, M. & Asakuma, N. Ultraviolet-reduced reduction and crystallization of indium oxide films. J. Appl. Phys. 85, 203–207 (1999)
Park, Y. M., Daniel, J., Heeney, M. & Salleo, A. Room-temperature fabrication of ultrathin oxide gate dielectrics for low-voltage operation of organic field-effect transistors. Adv. Mater. 23, 971–974 (2011)
Hwang, S., Lee, J. H., Woo, C. H., Lee, J. Y. & Cho, H. K. Effect of annealing temperature on the electrical performances of solution-processed InGaZnO thin film transistors. Thin Solid Films 519, 5146–5149 (2011)
Lim, W. et al. Improvement in bias stability of amorphous-InGaZnO4 thin film transistors with SiOx passivation layers. J. Vac. Sci. Technol. B 28, 116–119 (2010)
Son, K.-S. et al. Highly stable double-gate Ga-In-Zn-O thin-film transistor. Electron Dev. Lett. 31, 812–814 (2010)
Cho, E. N., Kang, J. H., Kim, C. E., Moon, P. & Yun, I. Analysis of bias stress instability in amorphous InGaZnO thin-film transistors. IEEE Trans. Device Mater. Reliab. 11, 112–117 (2011)
Choi, H. S. et al. Influence of Hf contents on interface state properties in a-HfInZnO thin-film transistors with SiNx/SiOx gate dielectrics. Appl. Phys. Lett. 99, 183502 (2011)
We acknowledge discussions with C.-I. Kim, S.-H. Song, H.-I. Kwon, B.-S. Bae, Y. Hong, S. Lim, J.-I. Han, M. J. Lee, A. Fenoglio and K.-H. Kim. This work was partially supported by Basic Science Research Program (no. 2010-0002623) and World-Class University Program (no. R31-10026) through a National Research Foundation of Korea (NRF) grant funded by the Ministry of Education, Science, and Technology.
The authors declare no competing financial interests.
About this article
Cite this article
Kim, YH., Heo, JS., Kim, TH. et al. Flexible metal-oxide devices made by room-temperature photochemical activation of sol–gel films. Nature 489, 128–132 (2012). https://doi.org/10.1038/nature11434
Nature Communications (2022)
Efficient synthesis of enwrapped CuO@rGO nanowire arrays to improve supercapacitor electrode performance
Journal of Applied Electrochemistry (2022)
Sol–gel preparation of Sn doped gallium oxide films for application in solar-blind ultraviolet photodetectors
Journal of Materials Science (2022)
Solution-Processed HfO2/Y2O3 Multilayer Si-Based MOS Capacitors Photoactivated by Deep-Ultraviolet Radiation
Journal of Electronic Materials (2022)
Performance Enhancement of In2O3 Thin-Film Transistors via Multi-Spin Coating Combined with UV-Assisted Thermal Annealing
Journal of Electronic Materials (2022)