LIGHT-EMITTING DISPLAY DEVICE

• US 20100096654A1
• Filed: 10/15/2009
• Published: 04/22/2010
• Est. Priority Date: 10/16/2008
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: GODO, Hiromichi
• Granted Patent: US 8,704,267 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

The light-emitting display device comprises first and second thin film transistors. The first thin film transistor includes a first gate electrode; a first oxide semiconductor film; and a first electrode and a second electrode which are electrically connected to the first oxide semiconductor film. The second thin film transistor includes a second gate electrode electrically connected to the second electrode; a second oxide semiconductor film; a third electrode; a light-emitting layer and a fourth electrode over the second oxide semiconductor film. A work function of the second oxide semiconductor film is higher than a work function of the fourth electrode.

Claims

1. A light-emitting display device comprising:

a gate electrode over a substrate;

a gate insulating film over the gate electrode;

an oxide semiconductor film over the gate insulating film;

a first electrode electrically connected to the oxide semiconductor film;

a light-emitting layer on and in contact with the oxide semiconductor film; and

a second electrode over the light-emitting layer.

2. The light-emitting display device according to claim 1, wherein a work function of the oxide semiconductor film is higher than a work function of the second electrode.

3. The light-emitting display device according to claim 1, wherein the oxide semiconductor film is represented by InMO₃(ZnO)_m (m>

0), and each include, as the M, one or more metal elements of gallium (Ga), iron (Fe), nickel (Ni), manganese (Mg), and cobalt (Co).

4. The light-emitting display device according to claim 1, wherein the gate electrode comprises a conductive film having a light-blocking property, and the second electrode comprises a conductive film having a light-transmitting property.

5. The light-emitting display device according to claim 1, wherein the gate electrode comprises a conductive film having a light-transmitting property, and the second electrode comprises a conductive film having a light-blocking property.

6. The light-emitting display device according to claim 1, wherein the gate electrode comprises a conductive film having a light-transmitting property, and the second electrode comprises a conductive film having a light-transmitting property.

7. The light-emitting display device according to claim 1, wherein the light-emitting layer comprises one light emitting layer and at least one of a hole-injecting layer, a hole-transporting layer, an electron-transporting layer, and an electron-injecting layer.

8. A light-emitting display device comprising:

a first gate electrode and a second gate electrode;

a gate insulating film over the first gate electrode and the second gate electrode;

a first oxide semiconductor film over the first gate electrode with the gate insulating film interposed therebetween;

a first electrode and a second electrode which are electrically connected to the first oxide semiconductor film, the second electrode being electrically connected to the second gate electrode;

a second oxide semiconductor film over the second gate electrode with the gate insulating film interposed therebetween;

a third electrode electrically connected to the second oxide semiconductor film;

a light-emitting layer on and in contact with the second oxide semiconductor film; and

a fourth electrode over the light-emitting layer.

9. The light-emitting display device according to claim 8, wherein a work function of the second oxide semiconductor film is higher than a work function of the fourth electrode.

10. The light-emitting display device according to claim 8, wherein the first oxide semiconductor film and the second oxide semiconductor film are each represented by InMO₃(ZnO)_m (m>

0), and each include, as the M, one or more metal elements of gallium (Ga), iron (Fe), nickel (Ni), manganese (Mg), and cobalt (Co).

11. The light-emitting display device according to claim 8, wherein the second gate electrode comprises a conductive film having a light-blocking property, and the fourth electrode comprises a conductive film having a light-transmitting property.

12. The light-emitting display device according to claim 8, wherein the second gate electrode comprises a conductive film having a light-transmitting property, and the fourth electrode comprises a conductive film having a light-blocking property.

13. The light-emitting display device according to claim 8, wherein the second gate electrode comprises a conductive film having a light-transmitting property, and the fourth electrode comprises a conductive film having a light-transmitting property.

14. A light-emitting display device comprising:

a first thin film transistor comprising;

a first gate electrode;

a gate insulating film over the first gate electrode;

a first oxide semiconductor film over the gate insulating film; and

a first electrode and a second electrode which are electrically connected to the first oxide semiconductor film; and

a second thin film transistor comprising;

a second gate electrode electrically connected to the second electrode;

the gate insulating film over the second gate electrode;

a second oxide semiconductor film over the gate insulating film;

a third electrode electrically connected to the second oxide semiconductor film;

a light-emitting layer on and in contact with the second oxide semiconductor film; and

a fourth electrode over the light-emitting layer.

15. The light-emitting display device according to claim 14, wherein a work function of the second oxide semiconductor film is higher than a work function of the fourth electrode.

16. The light-emitting display device according to claim 14, wherein the first oxide semiconductor film and the second oxide semiconductor film are each represented by InMO₃(ZnO)_m (m>

0), and each include, as the M, one or more metal elements of gallium (Ga), iron (Fe), nickel (Ni), manganese (Mg), and cobalt (Co).

17. The light-emitting display device according to claim 14, wherein the second gate electrode comprises a conductive film having a light-blocking property, and the fourth electrode comprises a conductive film having a light-transmitting property.

18. The light-emitting display device according to claim 14, wherein the second gate electrode comprises a conductive film having a light-transmitting property, and the fourth electrode comprises a conductive film having a light-blocking property.

19. The light-emitting display device according to claim 14, wherein the second gate electrode comprises a conductive film having a light-transmitting property, and the fourth electrode comprises a conductive film having a light-transmitting property.