Field effect transistor with amorphous oxide

摘要

A novel amorphous oxide film applicable, for example, to an active layer of a TFT is provided. The amorphous oxide in the film has an electron carrier concentration of less than 10 18 /cm 3 at a temperature of 25° C, wherein the amorphous oxide is any one selected from the group consisting of an oxide containing In, Zn, and Sn; an oxide containing In and Zn; an oxide containing In and Sn; and an oxide containing In, Ga, and Zn. The oxide chemical composition changes in the layer thickness direction in the film interior such that there is a region with a first chemical composition and a region with a second chemical composition other than said first composition.