High breakdown voltage ZnMgO/In-Ga-Zn-O heterostructure transistors

ZnO-based semiconductors with the wide-band gap have attracted great interest for electronic and optical applications. Among them, an amorphous In-Ga-Zn-O (a-IGZO) has been intensively studied. The thin-film transistors using of a-IGZO as an active n-channel layer exhibit good performances such as the high field-effect mobility [μ_FE ~ 10 cm² (Vs)^-1], I_on/I_off ratio of ~10⁸, and excellent process stability, even when the channel layer was deposited at room temperature (RT). The band gap of a-IGZO was estimated to E_g = 3.1-3.4 eV from several spectroscopic techniques, which is a promising candidate for high voltage applications such as switching devices for power supplies. Moreover, a-IGZO films have the high uniformity in large area owing to the amorphous character, which results in low-cost fabrication.