Thin film transistor, display device, and electronic device
View Patent ↗A thin film transistor, which is capable of improving carrier mobility, and a display device and an electronic device, each of which uses the thin film transistor, are provided. The thin film transistor includes: a gate electrode; an oxide semiconductor layer including a multilayer film including a carrier travel layer configuring a channel and a carrier supply layer for supplying carriers to the carrier travel layer; a gate insulating film provided between the gate electrode and the oxide semiconductor layer; and a pair of electrodes as a source and a drain. A conduction band minimum level or a valence band maximum level corresponding to a carrier supply source of the carrier supply layer is higher in energy than a conduction band minimum level or a valence band maximum level corresponding to a carrier supply destination of the carrier travel layer.
1. A thin film transistor comprising:
a gate electrode;
an oxide semiconductor layer including a multilayer film, the multiplayer film including a carrier travel layer acting as a channel and a carrier supply layer for supplying carriers to the carrier travel layer;
a gate insulating film provided between the gate electrode and the oxide semiconductor layer; and
a pair of electrodes acting as a source and a drain respectively,
wherein,
the carrier supply layer has a higher conduction band minimum energy level than that of the carrier travel layer, or
the carrier supply layer has a higher valence band maximum energy level than that of the carrier travel layer.
2. The thin film transistor according to claim 1 , wherein the oxide semiconductor layer includes a high-resistance layer between the carrier travel layer and the carrier supply layer, the high-resistance layer having a relatively low carrier concentration.
3. The thin film transistor according to claim 1 , wherein the oxide semiconductor layer includes a single heterostructure, the single heterostructure having the carrier travel layer and the carrier supply layer, each layer being a single layer.
4. The thin film transistor according to claim 1 , wherein the oxide semiconductor layer includes a double heterostructure, the double heterostructure having a pair of carrier supply layers on a top and a bottom of one carrier travel layer, respectively.
5. The thin film transistor according to claim 1 , wherein the oxide semiconductor layer includes a double heterostructure, the double heterostructure having a pair of carrier travel layers on a top and a bottom of one carrier supply layer, respectively.
6. The thin film transistor according to claim 1 , wherein:
the carriers are electrons, and
a conduction band minimum level of the carrier supply layer is higher in energy than a conduction band minimum level of the carrier travel layer.
7. The thin film transistor according to claim 1 , wherein:
the carriers are holes, and
the carrier supply layer has a higher valence band maximum energy level than that of the carrier travel layer.
8. The thin film transistor according to claim 1 , wherein the carrier supply layer comprises Al x Ga y In z O 1.5x+1.5y+1.5z (x, y, z: integer).
9. The thin film transistor according to claim 8 , wherein the carrier travel layer comprises Al x Ga y In z O 1.5x+1.5y+1.5z (x, y, z: integer).
10. The thin film transistor according to claim 1 , wherein at least one layer of the multilayer film of the oxide semiconductor layer comprises amorphous semiconductor.
11. The thin film transistor according to claim 1 , wherein at least one layer of the multilayer film of the oxide semiconductor layer comprises polycrystalline semiconductor.
12. The thin film transistor according to claim 1 , wherein the gate electrode is between the gate insulating film and a substrate.
13. The thin film transistor according to claim 1 , wherein the oxide semiconductor layer is between the gate insulating film and a substrate.
14. The thin film transistor of claim 1 , wherein the carrier travel layer comprises amorphous semiconductor.
15. The thin film transistor of claim 1 , wherein the carrier supply layer comprises amorphous semiconductor.
16. The thin film transistor of claim 1 , wherein the carrier travel layer comprises polycrystalline semiconductor.
17. The thin film transistor of claim 1 , wherein the carrier supply layer comprises polycrystalline semiconductor.