THIN FILM FIELD EFFECT TRANSISTOR AND DISPLAY

• US 20090236596A1
• Filed: 03/04/2009
• Published: 09/24/2009
• Est. Priority Date: 03/24/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Itai, Yuichiro
• Granted Patent: US 8,188,480 B2
• Time in Patent Office: Days
• US Class Current: 257/43
• CPC Class Codes: H01L 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A TFT is provided which includes, on a substrate, at least a gate electrode, a gate insulating layer, an active layer containing an amorphous oxide semiconductor, a source electrode and a drain electrode, wherein a resistance layer containing an amorphous oxide and having a thickness of more than 3 nm is disposed between the active layer and at least one of the source electrode or the drain electrode, and a band gap of the active layer is smaller than a band gap of the resistance layer. Also, a display using the TFT is provided.

Claims

1. A thin film field effect transistor comprising, on a substrate, at least a gate electrode, a gate insulating layer, an active layer containing an amorphous oxide semiconductor, a source electrode and a drain electrode, wherein a resistance layer containing an amorphous oxide and having a thickness of more than 3 nm is disposed between the active layer and at least one of the source electrode or the drain electrode, and a band gap of the active layer is smaller than a band gap of the resistance layer.

2. The thin film field effect transistor according to claim 1, wherein the band gap of the active layer is 2.0 eV or more and less than 4.0 eV.

3. The thin film field effect transistor according to claim 1, wherein the band gap of the resistance layer is 4.0 eV or more and less than 15.0 eV.

4. The thin film field effect transistor according to claim 1, wherein a difference between the band gap of the active layer and the band gap of the resistance layer is 0.1 eV or more and less than 13.0 eV.

5. The thin film field effect transistor according to claim 1, wherein a carrier concentration of the active layer is higher than a carrier concentration of the resistance layer.

6. The thin film field effect transistor according to claim 1, wherein a film thickness of the resistance layer is from 5 nm to 80 nm.

7. The thin film field effect transistor according to claim 1, wherein the amorphous oxide semiconductor in the active layer includes at least one element selected from the group consisting of In, Sn, Zn, and Cd.

8. The thin film field effect transistor according to claim 1, wherein the amorphous oxide in the resistance layer includes at least one element selected from the group consisting of Ga, Mg, Al, Ca, and Si.

9. The thin film field effect transistor according to claim 1, wherein two layers comprising the active layer and the resistance layer are disposed between the gate insulating layer, and the source electrode or the drain electrode.

10. The thin film field effect transistor according to claim 1, wherein the active layer and the resistance layer are layers each formed by a sputtering method.

11. The thin film field effect transistor according to claim 1, wherein the substrate is a flexible substrate.

12. A display including a light-emitting element having a pair of electrodes and a light emission layer interposed between the electrodes, and a field effect transistor for driving the light-emitting element, wherein the field effect transistor is the thin film field effect transistor according to claim 1.