Bandgap-Engineered Ga-Rich GaZnO Thin Films for UV Transparent Electronics

Ga-rich GaZnO thin films were prepared by metal-organic chemical vapor deposition. The optical bandgap of GaZnO films can be engineered from 3.3 to 4.9 eV by varying the Ga content. The film is amorphortized and the resistivity increases with an increase of Ga content. The Ga-rich GaZnO alloy with lower resistivity is investigated as a UV transparent conductor, while the semi-insulating Ga-rich GaZnO film with high transparency at 280-900 nm is employed as the channel layer to fabricate deep UV transparent thin-film transistor. The transistor shows a typical n-channel field-effect characteristic with a current on/off ratio of 10⁴ - 10⁵, a threshold voltage of ~42 V, a saturated field-effect mobility of ~0.06 cm² middot V^-1 middot s^-1, and a subthreshold swing of ~7.7 V middot decade^-1.