Metallization strategies for In2O3-based amorphous oxide semiconductor materials


Amorphous oxide semiconductors based on indium oxide [e.g., In–Zn–O (IZO) and In–Ga–Zn–O (IGZO)] are of interest for use in thin-film transistor (TFT) applications. We report that the stability of amorphous In–Zn–O (a-IZO) used in TFT applications depends, in part, on the metallization materials used to form the source and drain contacts. A thermodynamics-based approach to the selection of IZO metallization materials is presented along with a study of the microstructural stability of a-IZO metallized with Mo and Ti. In situ transmission electron microscopy (TEM), x-ray diffraction, and atomic force microscopy studies are presented that show that the crystallization temperature of a-IZO metallized with Ti is sharply reduced (to ≅200 °C), while a-IZO metallized with Mo remains amorphous. The effects of the unstable Ti/IZO interface are shown to include: vacancy injection, enhanced amorphous-to-crystal transformation kinetics, interfacial oxide formation, and the lateral growth on adjacent IZO of rutile TiO2 needles.

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The authors gratefully acknowledge the financial support of the National Science Foundation (NSF) Award No. DMR-0804915.

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Correspondence to David C. Paine.

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Lee, S., Park, K. & Paine, D.C. Metallization strategies for In2O3-based amorphous oxide semiconductor materials. Journal of Materials Research 27, 2299–2308 (2012).

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