Effect of nitrogen addition on the structural, electrical, and optical properties of In-Sn-Zn oxide thin films

• Published in: Applied surface science 2017-02, Vol.396, p.897-901
• Main Authors: Jia, Junjun, Torigoshi, Yoshifumi, Suko, Ayaka, Nakamura, Shin-ichi, Kawashima, Emi, Utsuno, Futoshi, Shigesato, Yuzo
• Format: Article
• Language: English
• Subjects: Amorphous oxide semiconductor; Indium-Tin-Zinc oxide (ITZO) film; Negative-bias-illumination stress-induced instability; Nitrogen addition
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.11.058

•Nitrogen addition induces the structure of ITZO film change from amorphous phase to a c-axis oriented InN polycrystalline phase.•Nitrogen addition suppressed the formation of oxygen-related vacancies in ITZO films.•A red-shift in the optical band edge for ITZO films was observed as the nitrogen flow ratio increased, which was due to the generation of InN crystallites. Indium-tin-zinc oxide (ITZO) films were deposited at various nitrogen flow ratios using magnetron sputtering. At a nitrogen flow ratio of 40%, the structure of ITZO film changed from amorphous, with a short-range-ordered In2O3 phase, to a c-axis oriented InN polycrystalline phase, where InN starts to nucleate from an amorphous In2O3 matrix. Whereas, nitrogen addition had no obvious effect on the structure of indium-gallium-zinc oxide (IGZO) films even at a nitrogen flow ratio of 100%. Nitrogen addition also suppressed the formation of oxygen-related vacancies in ITZO films when the nitrogen flow ratio was less than 20%, and higher nitrogen addition led to an increase in carrier density. Moreover, a red-shift in the optical band edge was observed as the nitrogen flow ratio increased, which could be attributed to the generation of InN crystallites. We anticipate that the present findings demonstrating nitrogen-addition induced structural changes can help to understand the environment-dependent instability in amorphous IGZO or ITZO based thin-film transistors (TFTs).