Relationship between non-localized tail states and carrier transport in amorphous oxide semiconductor, In-Ga-Zn-O

✍ Scribed by Nomura, K. ;Kamiya, T. ;Ohta, H. ;Shimizu, K. ;Hirano, M. ;Hosono, H.

• Book ID: 105364903
• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 375 KB
• Volume: 205
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200778936

✦ Synopsis

Abstract

The relationship between non‐localized tail states and carrier transport in transparent amorphous oxide semiconductor, In–Ga–Zn–O (a‐IGZO), was investigated. It was found that the energy width (E~0~) of the non‐localized tail states varied from <7 meV to 20 meV depending on the film deposition conditions (i.e. film quality). At carrier concentrations of ∼10^19^ cm^–3^, Hall mobilities larger than 10 cm^2^ (V s)^–1^ were obtained for the high‐quality films, while they were only several cm^2^ (V s)^–1^ for low‐quality films that have large E~0~ values ∼20 meV. However, even for low‐quality films, the E~0~ value decreased from 20 meV to 7 meV and their Hall mobilities were increased from ∼1 cm^2^ to >10 cm^2^ (V s)^–1^ by post thermal annealing at ≥300 °C. These observations indicate that structural relaxation associated with electron transport starts from ∼300 °C, which is much lower than the crystallization temperature (∼520 °C). This situation is similar to the case of amorphous metals. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)