Light-emitting device and method of fabricating the same

• US 7,208,755 B2
• Filed: 03/16/2004
• Issued: 04/24/2007
• Est. Priority Date: 03/27/2003
• Status: Expired due to Fees

• Current Assignee: Shin-Etsu Handotai Co., Ltd. (Shin-Etsu Chemical Company Limited)
• Original Assignee: Shin-Etsu Handotai Co., Ltd. (Shin-Etsu Chemical Company Limited)
• Inventors: Ishizaki, Jun-ya
• Primary Examiner(s): Le; Thao X.
• Assistant Examiner(s): Hafiz; Mursalin B.
• Application Number:
  US10/550,298
• Publication Number:
  US 20060220029A1
• Time in Patent Office: 1,134 Days
• Field of Search: 257/12, 257/22, 257/43
• US Class Current: 257/22
• CPC Class Codes: H01L 33/28 containing only elements of Group II and Group VI of the Periodic Table

Abstract

A light emitting device 1 has formed therein a light emitting layer section 24 based on a double heterostructure in which a p-type cladding layer 34, an active layer 33 and an n-type cladding layer 32, individually composed of a Mg_aZn_1-aO (0≦a≦1) type oxide, are stacked in this order, and uses a face on the n-type cladding layer side as a light extraction surface. The device also has, as being provided on the main surface on the light extraction surface side of the n-type cladding layer 32, an n-type low resistivity layer 35 composed of a Mg_aZn_1-aO type oxide, and having a content of an n-type dopant larger than that in the n-type cladding layer 32. There is thus provided a light emitting device of Mg_aZn_1-aO-type oxide base, excellent in the light extraction efficiency, having the light emitting layer section composed of a Mg_aZn_1-aO-type oxide, and a high conductivity MgZnO-base compound semiconductor layer disposed on the light extraction surface side.

Claims

1. A light emitting device having formed therein a light emitting layer section based on a double heterostructure in which a p-type cladding layer, an active layer and an n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, are stacked in this order, the device using a face on the n-type cladding layer side as a light extraction surface, and having, as being provided on the main surface on the light extraction surface side of the n-type cladding layer, an n-type low resistivity layer composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, and having a content of an n-type dopant larger than that in the n-type cladding layer.

2. The light emitting device as claimed in claim 1, having a metal bonding pad provided so as to cover a part of the main surface of the n-type low resistivity layer.

3. The light emitting device as claimed in claim 1, wherein the n-type low resistivity layer has an effective carrier concentration of 1×

10¹⁷/cm³ to 1×

10²⁰/cm³, both ends inclusive.

4. The light emitting device as claimed in claim 3, wherein the n-type low resistivity layer has an n-type dopant concentration of 1×

10¹⁷/cm³ to 1×

10²⁰/cm³, both ends inclusive.

5. The light emitting device as claimed in claim 1, wherein the n-type low resistivity layer contains, as the n-type dopant, one of or more of B, Al, Ga and In.

6. The light emitting device as claimed in claim 1, wherein the n-type low resistivity layer is grown as a Mg_aZn_1-aO-type oxide layer by MOVPE process, while incorporating therein the n-type impurity in the growth step.

7. The light emitting device as claimed in claim 1, wherein the n-type low resistivity layer is obtained by initially being grown in vapor phase in a form of a Mg_aZn_1-aO-type oxide layer having an n-type dopant concentration lower than the final n-type dopant concentration, and then by allowing the n-type dopant to additionally diffuse therein from the main surface of the layer.

8. The method of fabricating a light emitting device as claimed in claim 1, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

9. The light emitting device as claimed in claim 2, wherein the n-type low resistivity layer has an effective carrier concentration of 1×

10¹⁷/cm³ to 1×

10²⁰/cm³, both ends inclusive.

10. The light emitting device as claimed in claim 9, wherein the n-type low resistivity layer has an n-type dopant concentration of 1×

10¹⁷/cm³ to 1×

10²⁰/cm³, both ends inclusive.

11. The light emitting device as claimed in claim 2, wherein the n-type low resistivity layer contains, as the n-type dopant, one or more of B, Al, Ga and In.

12. The light emitting device as claimed in claim 2, wherein the n-type low resistivity layer is grown as a Mg_aZn_1-aO-type oxide layer by MOVPE process, while incorporating therein the n-type impurity in the growth step.

13. The light emitting device as claimed in claim 2, wherein the n-type low resistivity layer is obtained by initially being grown in vapor phase in a form of a Mg_aZn_1-aO-type oxide layer having an n-type dopant concentration lower than the final n-type dopant concentration, and then by allowing the n-type dopant to additionally diffuse therein from the main surface of the layer.

14. The light emitting device as claimed in claim 3, wherein the n-type low resistivity layer is obtained by initially being grown in vapor phase in a form of a Mg_aZn_1-aO-type oxide layer having an n-type dopant concentration lower than the final n-type dopant concentration, and then by allowing the n-type dopant to additionally diffuse therein from the main surface of the layer.

15. The light emitting device as claimed in claim 9, wherein the n-type low resistivity layer is obtained by initially being grown in vapor phase in a form of a Mg_aZn_1-aO-type oxide layer having an n-type dopant concentration lower than the final n-type dopant concentration, and then by allowing the n-type dopant to additionally diffuse therein from the main surface of the layer.

16. The method of fabricating a light emitting device as claimed in claim 2, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

17. The method of fabricating a light emitting device as claimed in claim 3, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

18. The method of fabricating a light emitting device as claimed in claim 9, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

19. The method of fabricating a light emitting device as claimed in claim 4, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

20. The method of fabricating a light emitting device as claimed in claim 10, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

21. The method of fabricating a light emitting device as claimed in claim 5, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

22. The method of fabricating a light emitting device as claimed in claim 11, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

23. The method of fabricating a light emitting device as claimed in claim 6, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

24. The method of fabricating a light emitting device as claimed in claim 12, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

25. The method of fabricating a light emitting device as claimed in claim 7, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

26. The method of fabricating a light emitting device as claimed in claim 13, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

27. The method of fabricating a light emitting device as claimed in claim 14, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.

28. The method of fabricating a light emitting device as claimed in claim 15, wherein, in the process of formation of the light emitting layer section having a double heterostructure by growing, in vapor phase, the p-type cladding layer, the active layer and the n-type cladding layer, individually composed of a Mg_aZn_1-aO (0≦

a≦

1) type oxide, sequentially in this order, the device after formation of the p-type cladding layer is annealed in an oxidative gas atmosphere, and the active layer and the n-type cladding layer are then grown in vapor phase.