Semiconductor light emitting device growing active layer on textured surface

• US 9,911,896 B2
• Filed: 07/06/2010
• Issued: 03/06/2018
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds LLC (Apollo Global Management, Inc.), Koninklijke Philips N.V.
• Inventors: Yi, Sungsoo, Gardner, Nathan F., Krames, Michael R., Romano, Linda T.
• Primary Examiner(s): SAYADIAN, HRAYR
• Application Number:
  US12/830,885
• Publication Number:
  US 20100264454A1
• Time in Patent Office: 2,800 Days
• Field of Search: 257 97, 257 99, 257101, 257103, 257E33005, 257E33055, 257E33074
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

In accordance with embodiments of the invention, at least partial strain relief in a light emitting layer of a III-nitride light emitting device is provided by configuring the surface on which at least one layer of the device grows such that the layer expands laterally and thus at least partially relaxes. This layer is referred to as the strain-relieved layer. In some embodiments, the light emitting layer itself is the strain-relieved layer, meaning that the light emitting layer is grown on a surface that allows the light emitting layer to expand laterally to relieve strain. In some embodiments, a layer grown before the light emitting layer is the strain-relieved layer. In a first group of embodiments, the strain-relieved layer is grown on a textured surface.

Claims

1. A device comprising:

a III-nitride semiconductor structure comprising;

a first n-type layer including a textured surface, the textured surface having a cross sectional profile of peaks alternating with valleys; and

a second n-type layer with at least partial strain relief grown over the textured surface, the layer with at least partial strain relief comprising islands formed on the peaks, the islands expanding laterally to provide the at least partial strain relief;

a light emitting layer with at least partial strain relief, the light emitting layer having a top surface that is planar and not textured, the light emitting layer being disposed on the second n-type layer within 1000 angstroms of the textured surface; and

a p-type region disposed over the light emitting layer.

2. The device of claim 1 wherein the textured surface comprises features lithographically formed on a III-nitride layer.

3. The device of claim 1 wherein:

the light emitting layer is InGaN;

the material of the light emitting layer has a bulk lattice constant a_bulk corresponding to a lattice constant of a free standing material of the light emitting layer;

the light emitting layer emits light between 430 nm and 520 nm;

the light emitting layer has an in-plane lattice constant a_in-plane corresponding to a lattice constant of the light emitting layer as grown in the structure; and

(a_in-plane−

a_bulk)/a_bulk is less than 1%.

4. The device of claim 1 wherein the light emitting layer has a thickness greater than 50 angstroms.

5. The device of claim 1 wherein the light emitting layer is doped with silicon to a dopant concentration between 1×

10¹⁸ cm<sup>−

3</sup> and 1×

10²⁰ cm<sup>−

3</sup>.

6. The device of claim 1 further comprising:

contacts electrically connected to the n-type region and the p-type region; and

a cover disposed over the III-nitride semiconductor structure.

7. The device of claim 1 wherein a depth from a top of a peak to a bottom of a valley is less than 200 nm.

8. The device of claim 1 wherein the light emitting layer has been epitaxially grown over the textured surface.