Effects of working pressure and annealing on bulk density and nanopore structures in amorphous In–Ga–Zn–O thin-film transistors. (11th January 2017)

• Record Type: Journal Article
• Authors: Ide, Keisuke; Kikuchi, Mitsuho; Ota, Masato; Sasase, Masato; Hiramatsu, Hidenori; Kumomi, Hideya; Hosono, Hideo; Kamiya, Toshio
• Is Part Of: Japanese journal of applied physics. Volume 56:Number 3(2017)Supplement
• Publication Date: 2017-01-11
• Subjects: Physics -- Periodicals; 621.05
• DOI: 10.7567/JJAP.56.03BB03
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: Microstructures of amorphous In–Ga–Zn–O (a-IGZO) thin films of different densities were analyzed. Device-quality a-IGZO films were deposited under optimum conditions, e.g., the total pressure P tot = 0.55 Pa produced high film densities of ∼6.1 g/cm 3, while a very high P tot = 5.0 Pa produced low film densities of 5.5 g/cm 3 . Both films formed uniform high-density layers in the vicinity of the glass substrate, 10–20 nm in thickness depending on P tot, while their growth mode changed to a sparse columnar structure in thicker regions. X-ray reflectivity and in situ spectroscopic ellipsometry provided different results on densification by post deposition thermal annealing; i.e., the latter has a higher sensitivity. High- Z -contrast images obtained by high-angle annular dark-field scanning transmission electron microscopy were also useful for detecting nanometer-size non uniformity even in device-quality a-IGZO films.