Semiconductor device
An embodiment is a semiconductor device which includes a first oxide semiconductor layer over a substrate having an insulating surface and including a crystalline region formed by growth from a surface of the first oxide semiconductor layer toward an inside; a second oxide semiconductor layer over the first oxide semiconductor layer; a source electrode layer and a drain electrode layer which are in contact with the second oxide semiconductor layer; a gate insulating layer covering the second oxide semiconductor layer, the source electrode layer, and the drain electrode layer; and a gate electrode layer over the gate insulating layer and in a region overlapping with the second oxide semiconductor layer. The second oxide semiconductor layer is a layer including a crystal formed by growth from the crystalline region.
1. A transistor comprising:
a gate electrode; and
an oxide semiconductor layer including a region overlapping with the gate electrode with a gate insulating film therebetween,
wherein the gate electrode is over the oxide semiconductor layer,
wherein the oxide semiconductor layer comprises a first layer comprising two-component metal oxides comprising In and Zn, and a second layer comprising a channel formation region adjacent to the first layer, and
wherein the oxide semiconductor layer comprises a crystalline region whose c-axis is aligned in a direction perpendicular or substantially perpendicular to a surface of the oxide semiconductor layer.
2. The transistor according to claim 1 , wherein the second layer comprises a three-component metal oxide including indium, gallium, and zinc.
3. A transistor comprising:
a gate electrode; and
an oxide semiconductor layer including a region overlapping with the gate electrode with a gate insulating film therebetween,
wherein the gate electrode is over the oxide semiconductor layer,
wherein the oxide semiconductor layer comprises a first layer comprising two-component metal oxides comprising In and Zn, and a second layer comprising a channel formation region adjacent to the first layer, and
wherein the oxide semiconductor layer comprises a c-axis-aligned crystalline region.
4. The transistor according to claim 3 , wherein the second layer comprises a three-component metal oxide including indium, gallium, and zinc.
5. A transistor comprising:
a gate electrode; and
an oxide semiconductor layer including a region overlapping with the gate electrode with a gate insulating film therebetween,
wherein the gate electrode is below the oxide semiconductor layer,
wherein the oxide semiconductor layer comprises a first layer comprising two-component metal oxides comprising In and Zn, and a second layer comprising a channel formation region adjacent to the first layer, and
wherein the oxide semiconductor layer comprises a crystalline region whose c-axis is aligned in a direction perpendicular or substantially perpendicular to a surface of the oxide semiconductor layer.
6. The transistor according to claim 5 , wherein the second layer comprises a three-component metal oxide including indium, gallium, and zinc.
7. A transistor comprising:
a gate electrode; and
an oxide semiconductor layer including a region overlapping with the gate electrode with a gate insulating film therebetween,
wherein the gate electrode is below the oxide semiconductor layer,
wherein the oxide semiconductor layer comprises a first layer comprising two-component metal oxides comprising In and Zn, and a second layer comprising a channel formation region adjacent to the first layer, and
wherein the oxide semiconductor layer comprises a c-axis-aligned crystalline region.
8. The transistor according to claim 7 , wherein the second layer comprises a three-component metal oxide including indium, gallium, and zinc.