Nanostructure semiconductor light emitting device
A nanostructure semiconductor light emitting device includes a base layer, an insulating layer, a plurality of light emitting nanostructures, and a contact electrode. The base layer is formed of a first conductivity-type semiconductor material. The insulating layer is disposed on the base layer. Each light emitting nanostructure is disposed in a respective opening of a plurality of openings in the base layer, and includes a nanocore formed of the first conductivity-type semiconductor material, and an active layer and a second conductivity-type semiconductor layer sequentially disposed on a surface of the nanocore. The contact electrode is spaced apart from the insulating layer and is disposed on a portion of the second conductivity-type semiconductor layer. A tip portion of the light emitting nanostructure has crystal planes different from those on side surfaces of the light emitting nanostructure.
1. A core-shell structure semiconductor light emitting device, comprising:
a base layer formed of a first conductivity-type semiconductor material;
an insulating layer on the base layer and having a plurality of openings;
a plurality of light emitting core-shell structures each in a separate opening of the plurality of openings, the light emitting core-shell structures being spaced apart from each other, each light emitting core-shell structure including a core formed of the first conductivity-type semiconductor material, and a separate shell including an active layer and a second conductivity-type semiconductor layer sequentially disposed on surfaces of the core; and
a contact electrode spaced apart from the insulating layer and on a portion of the second conductivity-type semiconductor layer, the contact electrode being on at least a tip portion of each respective light emitting core-shell structure; and
an insulating protective layer filling a continuous whole space between the plurality of light emitting core-shell structures and contacting lower regions of the plurality of light emitting core-shell structures,
wherein the tip portion of each respective light emitting core-shell structure has crystal planes different from those on side surfaces of the respective light emitting core-shell structure.
2. The core-shell structure semiconductor light emitting device of claim 1 , wherein a distance between the contact electrode and the insulating layer is greater than approximately 50% of a height of the light emitting core-shell structure measured from a surface of the insulating layer.
3. The core-shell structure semiconductor light emitting device of claim 1 , wherein the light emitting core-shell structure has an aspect ratio (height:width) of 2:1 or higher where the width of the light emitting core-shell structure is measured along a surface of the insulating layer and a height of the light emitting core-shell structure is measured perpendicularly from the surface of the insulating layer.
4. The core-shell structure semiconductor light emitting device of claim 1 , wherein the contact electrode is disposed to cover the tip portion of the light emitting core-shell structure.
5. The core-shell structure semiconductor light emitting device of claim 4 , further comprising a current blocking intermediate layer disposed in at least one of a region between the active layer and the core and a region between the active layer and the second conductivity-type semiconductor layer to suppress a flow of current passing through the active layer in the tip portion of the light emitting core-shell structure.
6. The core-shell structure semiconductor light emitting device of claim 1 , wherein the contact electrode is on the side surfaces of the light emitting core-shell structure.
7. The core-shell structure semiconductor light emitting device of claim 6 , wherein the contact electrode disposed on the side surfaces of the light emitting core-shell structure is extended to a top portion of the side surfaces of the light emitting core-shell structure adjacent to the tip portion of the light emitting core-shell structure.
8. The core-shell structure semiconductor light emitting device of claim 6 , wherein the contact electrode is spaced apart from the tip portion of the light emitting core-shell structure by a predetermined distance, and the predetermined distance is less than approximately 10% of a height of the light emitting core-shell structure.
9. The core-shell structure semiconductor light emitting device of claim 6 , wherein the tip portion of the light emitting core-shell structure has a non-planarized surface.
10. The core-shell structure semiconductor light emitting device of claim 1 , wherein the contact electrode is on the insulating protective layer.
11. The core-shell structure semiconductor light emitting device of claim 1 , wherein the crystal planes on the side surfaces of the light emitting core-shell structure are perpendicular to an upper surface of the base layer.
12. The core-shell structure semiconductor light emitting device of claim 1 , wherein the contact electrode comprises a plurality of contact electrodes spaced apart from one another in a height direction of the light emitting core-shell structure.
13. The core-shell structure semiconductor light emitting device of claim 12 , wherein the light emitting core-shell structure has an aspect ratio (height:width) of 10:1 or higher where the width of the light emitting core-shell structure is measured along a surface of the insulating layer and a height of the light emitting core-shell structure is measured perpendicularly from the surface of the insulating layer.
14. The core-shell structure semiconductor light emitting device of claim 1 , wherein the contact electrode is a thick film that fills a portion of spaces between the light emitting core-shell structures.
15. A core-shell structure semiconductor light emitting device, comprising:
a base layer formed of a first conductivity-type semiconductor material;
an insulating layer on the base layer and having a plurality of openings;
a plurality of light emitting core-shell structures each in a separate opening of the plurality of openings, the light emitting core-shell structures being spaced apart from each other, each light emitting core-shell structure including a core formed of the first conductivity-type semiconductor material, and a separate shell including an active layer and a second conductivity-type semiconductor layer sequentially disposed on a surface of the core;
a first insulating protective layer filling a lower region of a continuous space between the plurality of light emitting core-shell structures and contacting lower portions of the plurality of light emitting core-shell structures;
a contact electrode on the first insulating protective layer and contacting a portion of the second conductivity-type semiconductor layer which is higher than half of a height of the light emitting core-shell structures the contact electrode being on at least a tip portion of each respective light emitting core-shell structure; and
a second insulating protective layer filling an upper region of the continuous spaces between the plurality of light emitting core-shell structures and covering the plurality of light emitting core-shell structures, the second insulating protective layer covering the tip portion of each respective light emitting core-shell structure, the second insulating protective layer having a uniform upper surface;
wherein the lowest level of contact portions between the contact electrode and the second conductivity-type semiconductor layer is determined by a thickness at which the first insulating protective layer is formed.
16. The core-shell structure semiconductor light emitting device of claim 15 , wherein the light emitting core-shell structures have planarized upper surfaces.
17. A core-shell structure semiconductor light emitting device, comprising:
a base layer formed of a first conductivity-type semiconductor material;
an insulating layer disposed on the base layer and having a plurality of openings;
a plurality of light emitting core-shell structures each in a separate opening of the plurality of openings, the light emitting core-shell structures being spaced apart from each other, each light emitting core-shell structure including a core formed of the first conductivity-type semiconductor material, and a separate shell including an active layer and a second conductivity-type semiconductor layer sequentially disposed on surfaces of the core; and
a contact electrode on lower regions of side surfaces of the light emitting core-shell structures adjacent to the insulating layer, wherein the contact electrode does not cover upper regions of the light emitting core-shell structures adjacent to tips of the light emitting core-shell structures, and wherein at least upper regions of the side surfaces of the light emitting core-shell structures are exposed from the contact electrode.
18. The core-shell structure semiconductor light emitting device of claim 17 , further comprising an insulating protective layer filling a space between the plurality of light emitting core-shell structures and contacting upper regions of the plurality of light emitting core-shell structures.