Amorphous oxide semiconductor material, field-effect transistor, and display device
There is provided an amorphous oxide semiconductor material including an amorphous oxide semiconductor including In, Ga and Zn, wherein when In:Ga:Zn=a:b:c denotes an element composition ratio of the oxide semiconductor, the element composition ratio is defined by the range of a+b=2 and b<2 and c<4b−3.2 and c>−5b+8 and 1≦c≦2.
1. An amorphous oxide semiconductor material comprising an amorphous oxide semiconductor including In, Ga and Zn, wherein when In:Ga:Zn=a:b:c denotes an element composition ratio of the oxide semiconductor, the element composition ratio is defined by the range of a+b=2 and 1.25≦b≦1.5 and c <4b−3.2 and c>−5b+8 and 1≦c≦2, and wherein an optical band gap of the amorphous oxide semiconductor material is equal to or greater than 3.85 eV.
2. A field-effect transistor having an active layer that comprises the amorphous oxide semiconductor material according to claim 1 and whose electrical conductivity σ is 10 −9 ≦σ≦10 −2 (S/cm).
3. The field-effect transistor according to claim 2 , wherein the amorphous oxide semiconductor material is heat-treated.
4. A display device equipped with the field-effect transistor according to claim 2 .
5. An amorphous oxide semiconductor material comprising an amorphous oxide semiconductor including In, Ga and Zn, wherein when In:Ga:Zn=a:b:c denotes an element composition ratio of the oxide semiconductor, the element composition ratio is defined by the range of a+b=2 and c<4b−3.2 and c<−5b+8 and 1≦c and 1.25≦b≦1.5, and an optical band gap of the amorphous oxide semiconductor material is equal to or greater than 3.85 eV.
6. A bottom-emission display device comprising:
a substrate;
the field-effect transistor according to claim 2 which is placed on the substrate and has a bottom-gate structure; and
an organic electroluminescent element that is electrically connected to the field-effect transistor on the substrate,
wherein light emitted from the organic electroluminescent element is produced from the substrate side.
7. A display device comprising:
a light-emitting layer configured to irradiate light at a wavelength of from 380 nm to 440 nm; and
an amorphous oxide semiconductor material comprising In, Ga and Zn, wherein when In:Ga:Zn=a:b:c denotes an element composition ratio of the oxide semiconductor, the element composition ratio is defined by the range of a+b=2 and 1.25≦b≦1.5 and c<4b−3.2 and c>−5b+8 and 1≦c≦2.
8. A display device comprising:
a light-emitting layer configured to irradiate blue light; and
an active layer including an amorphous oxide semiconductor material comprising In, Ga and Zn, wherein when In:Ga:Zn=a:b:c denotes an element composition ratio of the oxide semiconductor, the element composition ratio is defined by the range of a+b=2 and 1.25≦b≦1.5 and c<4b−3.2 and c>−5b+8 and 1≦c≦2.