US Patent 10032931 Switching element

A switching element of LCDs or organic EL displays which uses a thin film transistor device, includes: a drain electrode, a source electrode, a channel layer contacting the drain electrode and the source electrode, wherein the channel layer comprises indium-gallium-zinc oxide having a transparent, amorphous state of a composition equivalent to InGaO3(ZnO)m (wherein m is a natural number less than 6) in a crystallized state, and the channel layer has a semi-insulating property represented by an electron mobility of more than 1 cm2/(V·sec) and an electron carrier concentration is less than 1018/cm3, a gate electrode, and a gate insulating film positioned between the gate electrode and the channel layer.