GAP DISTRIBUTED BRAGG REFLECTORS

• US 20130050686A1
• Filed: 08/25/2011
• Published: 02/28/2013
• Est. Priority Date: 08/25/2011
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Wunderer, Thomas, Chua, Christopher L., Krusor, Brent S., Johnson, Noble M.
• Granted Patent: US 9,335,262 B2
• Time in Patent Office: Days
• US Class Current: 356/128
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01N 21/17 Systems in which incident light is modified in accordance with the properties of the material investigated where the material investigated is optically excited causing a change in wavelength of the incident light G01N21/63
• CPC Class Codes: G01N 21/41 Refractivity; Phase-affecting properties, e.g. optical path length G01N21/21 takes precedence
• CPC Class Codes: G01N 2201/0635 Structured illumination, e.g. with grating
• CPC Class Codes: G01N 2201/08 Optical fibres; light guides
• CPC Class Codes: G02B 5/0816 Multilayer mirrors, i.e. having two or more reflecting layers G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/085 at least one of the reflecting layers comprising metal
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 5/18308 having a special structure for lateral current or light confinement
• CPC Class Codes: H01S 5/18341 Intra-cavity contacts
• CPC Class Codes: H01S 5/18363 comprising air layers
• CPC Class Codes: H01S 5/18369 based on dielectric materials
• CPC Class Codes: H01S 5/18377 comprising layers of different kind of materials, e.g. combinations of semiconducting with dielectric or metallic layers
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

A device includes one or more reflector components. Each reflector component comprises layer pairs of epitaxially grown reflective layers and layers of a non-epitaxial material, such as air. Vias extend through at least some of the layers of the reflector components. The device may include a light emitting layer.

Claims

1. A method of making a device, comprising:

epitaxially growing a layer stack including one or more reflective layers and one or more interstitial layers, each interstitial layer disposed between two reflective layers; and

forming vias that intersect at least some of the layers;

exposing the interstitial layers to an etchant through the vias; and

etching the interstitial layers.

2. The method of claim 1, wherein the one or more reflective layers comprises two sets of one or more reflective layers and growing the device comprises growing a light emitting layer between the sets of reflective layers.

3. The method of claim 1, wherein growing the layer stack comprises growing only one reflective layer over or under a light emitting layer.

4. The method of claim 1, wherein:

forming the vias comprises dry etching the vias; and

exposing the interstitial layers to the etchant comprises exposing the interstitial layers to a wet etchant through the vias.

5. The method of claim 6, wherein forming the vias comprises forming the vias to surround a central region.

6. The method of claim 1, wherein the reflective layers and the interstitial layers comprise group III-nitride materials.

7. The method of claim 6, wherein the reflective layers and the interstitial layers comprise aluminum (Al) and the reflective layers have a lower Al content than the interstitial layers.

8. The method of claim 1, comprising forming air gaps between the reflective layers.

9. The method of claim 1, wherein etching the interstitial layers further comprises etching the interstitial layers for a predetermined period of time.

10. The method of claim 1, further comprising:

detecting a characteristic of the device; and

controlling the etching based on the detected characteristic.

11. The method of claim 10, wherein the characteristic comprises at least one of a color of a surface of the device and a reflectivity of the device.

12. A device comprising:

one or more reflector components, each reflector component comprising alternating epitaxially grown reflective layers and layers of a non-epitaxially grown material; and

one or more vias that extend through at least some of the layers of the non-epitaxially grown material.

13. The device of claim 12, wherein the non-epitaxially grown material comprises air.

14. The device of claim 12, wherein the one or more reflector components comprises two reflector components and a light emitting layer is between the two reflector components.

15. The device of claim 12, wherein the one or more reflective components comprises only one reflective component and the only one reflective component is above or below a light emitting layer.

16. The device of claim 12, wherein the non-epitaxially-grown material and the reflective layers have an index of refraction difference greater than about 0.6 at a target wavelength, λ

, of about 350 nm.

17. The device of claim 12, wherein:

the epitaxially grown reflective layers comprise GaN; and

the non-epitaxially grown material comprises air.

18. A device comprising:

one or more reflector components, each reflector component comprising pairs of alternating layers of an epitaxially grown nitride system material and interstitial gaps between the reflective layers, wherein the reflector components include fewer than about 20 pairs and have a reflectivity greater than about 99%; and

one or more vias that extend through at least some of the layers.

19. The device of claim 18, wherein the device comprises a vertical cavity surface emitting laser.

20. The device of claim 18, wherein air is disposed in the interstitial gaps.

21. A method, comprising:

exposing a device to an analyte, the device including a distributed Bragg reflector (DBR) comprising;

a plurality of reflective layers;

one or more interstitial gaps between the reflective layers; and

at least one opening configured to allow entry of an analyte into the interstitial gaps;

detecting one or more of a presence and a characteristic of the analyte based on one or more optical properties of the DBR.

22. A sensor, comprising:

a plurality of reflective layers;

one or more interstitial gaps between the reflective layers; and

at least one opening configured to allow entry of an analyte into the interstitial gaps, wherein the plurality of reflective layers and the interstitial gaps form a distributed Bragg reflector (DBR).