Ultra wide bandgap amorphous oxide semiconductor, Ga-Zn-O

Publication date: Available online 3 March 2016
Source:Thin Solid Films
Author(s): Junghwan Kim, Norihiko Miyokawa, Takumi Sekiya, Keisuke Ide, Yoshitake Toda, Hidenori Hiramatsu, Hideo Hosono, Toshio Kamiya
We fabricated amorphous oxide semiconductor films, a-(Ga1–x Zn x )O y , at room temperature on glass, which have widely tunable band gaps (E g) ranging from 3.47–4.12eV. The highest electron Hall mobility ~7 cm²V⁻¹ s⁻¹ was obtained for E g =~3.8eV. Ultraviolet photoemission spectroscopy revealed that the increase in E g with increasing the Ga content comes mostly from the deepening of the valence band maximum level while the conduction band minimum level remains almost unchanged. These characteristics are explained by their electronic structures. As these films can be fabricated at room temperature on plastic, this achievement extends the applications of flexible electronics to opto-electronic integrated circuits associated with deep ultraviolet region.