Amorphous oxide and thin film transistor
The present invention relates to an amorphous oxide and a thin film transistor using the amorphous oxide. In particular, the present invention provides an amorphous oxide having an electron carrier concentration less than 10 18 /cm 3 , and a thin film transistor using such an amorphous oxide. In a thin film transistor having a source electrode 6 , a drain electrode 5 , a gate electrode 4 , a gate insulating film 3 , and a channel layer 2 , an amorphous oxide having an electron carrier concentration less than 10 18 /cm 3 is used in the channel layer 2.
1. A thin film transistor device having a top-gate structure or a bottom-gate structure, comprising:
a drain electrode;
a source electrode;
a channel layer contacting the drain electrode and the source electrode;
a gate electrode; and
a gate insulating film positioned between the gate electrode and the channel layer,
wherein the channel layer comprises indium-gallium-zinc oxide having a transparent, amorphous state of a composition equivalent to InGaO 3 (ZnO) m (wherein m is a natural number less than 6) in a crystallized state, and
the channel layer is prepared by a sputtering method or a pulsed laser deposition method in an atmosphere containing oxygen gas, and has a semi-insulating property represented by an electron mobility of more than 1 cm 2 /(V·sec) and an electron carrier concentration of less than 10 16 /cm 3 as deposited state and as measured by Hall effect measurement at room temperature.
2. The thin film transistor device according to claim 1 , wherein the gate insulating film contains one or more selected from Al 2 O 3 , Y 2 O 3 , or HfO 2 .
3. The thin film transistor device according to claim 1 , wherein the substrate is one of a glass plate, a plastic plate or a plastic film.