Thin-Film LED Having a Mirror Layer and Method for the Production Thereof

• US 20100283073A1
• Filed: 09/04/2008
• Published: 11/11/2010
• Est. Priority Date: 09/28/2007
• Status: Active Grant

• Current Assignee: OSRAM OLED GMBH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Plaine, Glenn-Ives, Sabathil, Matthias, Hahn, Berthold, Weimar, Andreas, Baur, Johannes
• Granted Patent: US 9,252,331 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/405 Reflective materials

Abstract

A thin-film LED comprising a barrier layer (3), a first mirror layer (2) succeeding the barrier layer (3), a layer stack (5) succeeding the first mirror layer (2), and at least one contact structure (6) succeeding the layer stack (5). The layer stack (5) has at least one active layer (5a) which emits electromagnetic radiation. The contact structure (6) is arranged on a radiation exit area (4) and has a contact area (7). The first mirror layer (2) has, in a region lying opposite the contact area of the contact structure (6), a cutout which is larger than the contact area (7) of the contact structure (6). The efficiency of the thin-film LED is increased as a result.

Claims

1. A thin-film LED, comprising:

a barrier layer,

a first minor layer succeeding the barrier layer,

a layer stack succeeding the first mirror layer and having at least one active layer (5a) which emits electromagnetic radiation; and

at least one contact structure which succeeds the layer stack, is arranged on a radiation exit area and has a contact area, wherein the first mirror layer has, in a region lying opposite the contact area of the contact structure, a cutout which is larger than the contact area of the contact structure.

2. The thin-film LED as claimed in claim 1, wherein the lateral extent of the cutout is 5 μ

m to 20 μ

m larger than the lateral extent of the contact area of the contact structure.

3. The thin-film LED as claimed in claim 1, wherein an interface of the layer stack which lies opposite the radiation exit area is altered in the region of the cutout in such a way that the contact resistance between the layer stack and the cut-out region of the first mirror layer is increased.

4. The thin-film LED as claimed in claim 3, wherein the interface of the layer stack which lies opposite the radiation exit area is altered in the region of the cutout in such a way that the interface of the layer stack is not electrically conductive in the region of the cutout.

5. The thin-film LED as claimed in claim 1, wherein the cutout of the first mirror layer has a second mirror layer.

6. The thin-film LED as claimed in claim 1, wherein a main area of the contact structure which faces the layer stack has a reflective layer.

7. The thin-film LED as claimed in claim 1, wherein the radiation exit area of the layer stack is roughened.

8. The thin-film LED as claimed in claim 1, wherein the regions of the layer stack on which the contact structure is arranged have a smaller layer height than regions of the layer stack on which no contact structure is arranged.

9. The thin-film LED as claimed in claim 1, wherein at least one of the side areas of the layer stack has a further reflective layer.

10. The thin-film LED as claimed in claim 1, wherein a luminescence conversion layer is applied on the radiation exit area of the thin-film LED.

11. A method for producing a thin-film LED as claimed in claim 1, comprising the steps of:

providing a growth substrate;

epitaxially growing a layer stack suitable for generating electromagnetic radiation;

applying a first mirror layer, which has a cutout in a region lying opposite an intended region of a contact structure;

applying a barrier layer on the first mirror layer;

stripping the layer stack from the growth substrate; and

applying a contact structure, which has a contact area, on the opposite side of the layer stack with respect to the first mirror layer, wherein the contact structure is applied in a region lying opposite the cutout of the first mirror layer, and the contact area of the contact structure is smaller than the cutout of the first mirror layer.

12. The method as claimed in claim 11, wherein the interface of the layer stack is damaged before the application of the barrier layer in the region of the cutout of the first mirror layer by means of a plasma process or sputtering process.

13. The method as claimed in claim 12, wherein a second mirror layer is introduced into the cutout of the first mirror layer before the application of the barrier layer.

14. The method as claimed in claim 11, wherein the interface of the layer stack which lies opposite the first mirror layer is roughened before the application of the contact structure.

15. The method as claimed in claim 11, wherein before the contact structure is applied to the layer stack, a reflective layer is applied to the partial regions of the layer stack which are intended for the contact structure.