Contact Configuration for Optoelectronic Device

• US 20170098739A1
• Filed: 10/03/2016
• Published: 04/06/2017
• Est. Priority Date: 10/01/2015
• Status: Active Grant

• Current Assignee: Nitek, Inc.
• Original Assignee: Sensor Electronic Technology Incorporated (Seoul Semiconductor Co., Ltd.)
• Inventors: Gaevski, Mikhail, Shatalov, Maxim S., Dobrinsky, Alexander, Shur, Michael
• Granted Patent: US 10,147,848 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 31/022408 for devices characterised by at least one potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/02327 the optical elements being integrated or being directly associated to the device, e.g. back reflectors optical coatings H01L31/0216
• CPC Class Codes: H01L 31/03048 comprising a nitride compounds, e.g. InGaN
• CPC Class Codes: H01L 31/035236 Superlattices; Multiple quantum well structures
• CPC Class Codes: H01L 31/0392 including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate textured substrates H01L31/02366
• CPC Class Codes: H01L 31/109 the potential barrier being of the PN heterojunction type
• CPC Class Codes: H01L 31/1848 comprising nitride compounds, e.g. InGaN, InGaAlN
• CPC Class Codes: H01L 31/1852 comprising a growth substrate not being an AIIIBV compound
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/387 with a plurality of electrode regions in direct contact with the semiconductor body and being electrically interconnected by another electrode layer
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy

Abstract

An optoelectronic device with a multi-layer contact is described. The optoelectronic device can include a n-type semiconductor layer having a surface. A mesa can be located over a first portion of the surface of the n-type semiconductor layer and have a mesa boundary. A n-type contact region can be located over a second portion of the surface of the n-type semiconductor contact layer entirely distinct from the first portion, and be at least partially defined by the mesa boundary. A first n-type metallic contact layer can be located over at least a portion of the n-type contact region in proximity of the mesa boundary, where the first n-type metallic contact layer forms an ohmic contact with the n-type semiconductor layer. A second n-type metallic contact layer can be located over a second portion of the n-type contact region, where the second n-type metallic contact layer is formed of a reflective metallic material.

Claims

1. An optoelectronic device comprising:

a n-type semiconductor layer having a surface;

a mesa located over a first portion of the surface of the n-type semiconductor layer and having a mesa boundary;

a n-type contact region located over a second portion of the surface of the n-type semiconductor contact layer entirely distinct from the first portion, wherein the n-type contact region is at least partially defined by the mesa boundary;

a first n-type metallic contact layer located over at least a portion of the n-type contact region in proximity of the mesa boundary, wherein the first n-type metallic contact layer forms an ohmic contact with the n-type semiconductor layer; and

a second n-type metallic contact layer located over a second portion of the n-type contact region, wherein the second n-type metallic contact layer is formed of a reflective metallic material.

2. The optoelectronic device of claim 1, wherein the first n-type metallic layer and the second n-type metallic contact layer at least partially overlap.

3. The optoelectronic device of claim 1, wherein a third metallic contact layer is located over at least a portion of the first n-type metallic contact layer and at least a portion of the second n-type metallic contact layer.

4. The optoelectronic device of claim 1, wherein the n-type semiconductor layer comprises a group III nitride semiconductor.

5. The optoelectronic device of claim 1, wherein the first n-type metallic contact layer comprises a plurality of domains with each domain having a smallest characteristic length-scale being at least a current spreading length width of the n-type semiconductor contact layer.

6. The optoelectronic device of claim 1, wherein the second n-type metallic contact layer includes at least one target radiation scattering domain.

7. The optoelectronic device of claim 1, wherein the n-type semiconductor layer includes a plurality of vacancies, each of the plurality of vacancies having a depth of 0.1-50 microns and a lateral size of 0.1-20 microns.

8. The optoelectronic device of claim 7, further comprising a plurality of target radiation scattering material domains at least partially filling the vacancies.

9. The optoelectronic device of claim 7, wherein at least one of:

the first n-type metallic contact layer or the second n-type metallic contact layer, fills at least a portion of the plurality of vacancies.

10. The optoelectronic device of claim 1, wherein the n-type semiconductor layer comprises a set of angled side surfaces, wherein at least a portion of each angled side surface in the set of angled side surfaces forms an angle between approximately ten and approximately eighty degrees with a normal vector to a top surface of the n-type semiconductor contact layer.

11. The optoelectronic device of claim 1, wherein the mesa comprises a set of angled side surfaces, wherein at least a portion of each angled side surface in the set of angled side surfaces forms an angle between approximately ten and approximately eighty degrees with a normal vector of a top surface of the mesa.

12. The optoelectronic device of claim 1, further comprising:

a substrate; and

a buffer layer located over the substrate, wherein the n-type semiconductor layer is located over the buffer layer.

13. The optoelectronic device of claim 12, wherein a surface area of a top surface of the n-type semiconductor layer is at least 5% smaller than a surface area of a top surface of the buffer layer.

14. The optoelectronic device of claim 12, wherein a surface area of a top surface of the buffer layer is at least 5% smaller than a surface area of the top surface of the substrate.

15. The optoelectronic device of claim 12, wherein the buffer layer comprises a set of angled side surfaces, wherein at least a portion of each angled side surface in the set of angled side surfaces forms an angle between approximately ten and approximately eighty degrees with a normal vector of a top surface of the buffer layer.

16. The optoelectronic device of claim 1, wherein the mesa boundary includes a plurality of interconnected fingers, and wherein the first n-type metallic contact layer extends between the plurality of interconnected fingers.

17. An optoelectronic device comprising:

a n-type group III nitride semiconductor layer having a surface;

a mesa located over a first portion of the surface of the n-type group III nitride semiconductor layer and having a mesa boundary, wherein the mesa boundary includes a plurality of interconnected fingers;

a n-type contact region located over a second portion of the surface of the n-type group III nitride semiconductor contact layer entirely distinct from the first portion, wherein the n-type contact region is at least partially defined by the mesa boundary;

a first n-type metallic contact layer located over at least a portion of the n-type contact region in proximity of the mesa boundary, wherein the first n-type metallic contact layer forms an ohmic contact with the n-type group III nitride semiconductor layer, and wherein the first n-type metallic contact layer extends between the plurality of interconnected fingers; and

a second n-type metallic contact layer located over a second portion of the n-type contact region, wherein the second n-type metallic contact layer is formed of a reflective metallic material.

18. A method of fabricating an optoelectronic device comprising:

forming a mesa having a mesa boundary over a first portion of a n-type semiconductor layer, wherein the mesa includes an active semiconductor layer and a p-type semiconductor contact layer located on an opposite side of the active semiconductor layer as the n-type semiconductor layer, and wherein the n-type semiconductor layer has a n-type contact region located over a second portion of the surface of the n-type semiconductor contact layer entirely distinct from the first portion, wherein the n-type contact region is at least partially defined by the mesa boundary;

depositing a first n-type metallic contact layer over a first portion of the n-type contact region in proximity to the mesa boundary; and

depositing a second n-type metallic contact layer over a second portion of the n-type contact region.

19. The method of claim 18, wherein the first n-type metallic region and the second n-type metallic contact region at least partially overlap.

20. The method of claim 18, further comprising, prior to deposition of the first and the second n-type metallic contact layers, etching the n-type contact region to form a plurality of vacancies, wherein the plurality of vacancies have a depth of 0.1-50 microns and a lateral size of 0.1-20 microns.