Laser devices having a gallium and nitrogen containing semipolar surface orientation

• US 8,971,368 B1
• Filed: 03/11/2013
• Issued: 03/03/2015
• Est. Priority Date: 08/16/2012
• Status: Active Grant

• Current Assignee: Kyocera SLD Laser Incorporated (Kyocera Corporation)
• Original Assignee: Soraa Laser Diode, Inc. (Kyocera Corporation)
• Inventors: Raring, James W., Schmidt, Mathew, Huang, Hua, McLaurin, Melvin, Poblenz, Christiane, Ellis, Bryan
• Primary Examiner(s): Zhang, Yuanda
• Application Number:
  US13/794,410
• Time in Patent Office: 722 Days
• Field of Search: 372/44.011
• US Class Current: 372/44.011
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 5/0202 Cleaving
• CPC Class Codes: H01S 5/0287 Facet reflectivity
• CPC Class Codes: H01S 5/1039 Details on the cavity length
• CPC Class Codes: H01S 5/2018 Optical confinement, e.g. absorbing-, reflecting- or waveguide-layers
• CPC Class Codes: H01S 5/22 having a ridge or stripe structure
• CPC Class Codes: H01S 5/2201 in a specific crystallographic orientation
• CPC Class Codes: H01S 5/3013 AIIIBV compounds
• CPC Class Codes: H01S 5/3063 using Mg
• CPC Class Codes: H01S 5/320275 semi-polar orientation
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
• CPC Class Codes: H01S 5/4031 Edge-emitting structures

Abstract

Laser devices formed on a semipolar surface region of a gallium and nitrogen containing material are disclosed. The laser devices have a laser stripe configured to emit a laser beam having a cross-polarized emission state.

Claims

1. A laser device comprising:

a gallium and nitrogen containing material having a semipolar surface configured on an offcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51) plane, a (40-4-1) plane, (40-41) plane, a (30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2), or a (30-32) plane;

a laser stripe region formed overlying a portion of the semipolar surface, the laser stripe region being characterized by a cavity orientation substantially parallel to the projection of the c-direction, the laser stripe region having a first end and a second end;

the laser stripe region characterized by a length less than 300 μ

m;

a first facet provided on the first end of the laser stripe region;

a second facet provided on the second end of the laser stripe region;

an n-type cladding region overlying the semipolar surface;

an active region comprising at least one active layer region overlying the n-type cladding region, the active region comprising a quantum well region or a double hetero-structure region; and

a p-type cladding region overlying the active region;

wherein the laser stripe region is characterized by a width configured to emit a laser beam having a selected ratio of a first polarization state and a second polarization state, the width configured to emit the laser beam operable in a single lateral mode for an internal loss of less than 8 cm<sup>−

1</sup>.

2. The laser device of claim 1, wherein the laser stripe region is characterized by a length less than 200 μ

m, or wherein the laser stripe region is characterized by a length of less than 100 μ

m, or wherein the laser stripe region is characterized by a length less than 50 μ

m; and

wherein the n-type cladding region is substantially free from aluminum bearing materials.

3. The laser device of claim 1, wherein the laser device is configured to emit electromagnetic radiation in a wavelength range selected from a 400 nm to 435 nm range, a 435 nm to 480 nm range, a 480 nm to 505 nm range, and a 505 nm to 550 nm range.

4. The laser device of claim 1, wherein the first facet and the second facet are formed by a scribing and breaking process or wherein the first facet and the second facet are formed by an etching process.

5. The laser device of claim 4, wherein the etching process is selected from reactive ion etching (RIE), inductively coupled plasma (ICP) etching, and chemical assisted ion beam etching (CAIBE).

6. The laser device of claim 1, wherein the laser beam is configured as a cross-polarized emission;

wherein the first polarization state is a primary state and the second polarization state is a secondary state such that the power emitted in the second polarization state is at least 10% greater than, at least 20% greater than, at least 30% greater than, or at least 40% greater than the power emitted in the first polarization state.

7. The laser device of claim 1, wherein the laser beam is configured to emit in a polarized state wherein the first polarization state is a primary state and the second polarization state is a secondary state such that the power emitted in the second polarization state is at less than 10%, less than 5%, less than 1%, or less than 0.1% of the power emitted in the first polarization state.

8. The laser device of claim 1, wherein the laser device is configured for a pointer application, a display application, a medical application, a biological application, a manufacturing application, a projector application, a visual application, a communication application, or a metrology application.

9. The laser device of claim 1, wherein the laser stripe region is one of a plurality of laser stripes, wherein each of the plurality of laser stripes is configured in a parallel arrangement and is configured to emit in a polarized state wherein the first polarization state is a primary state and the second polarization state is a secondary state such that the power emitted in the second polarization state is less than 10%, less than 5%, less than 1%, or less than 0.1% the power emitted in the first polarization state.

10. The laser device of claim 1, wherein the offcut of the semipolar orientation is between +/−

4 degrees toward a c-plane, between +/−

10 degrees toward an a-plane, or between +/−

4 degrees toward a c-plane and between +/−

10 degrees toward an a-plane.

11. The laser device of claim 1, wherein the laser stripe region is configured to emit a linearly polarized laser beam, a circularly polarized laser beam, or an elliptically polarized laser beam.

12. A laser device comprising:

a gallium and nitrogen containing material having a semipolar surface configured on an offcut orientation to one of either a (30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2), or a (30-32) plane;

an array of N single lateral mode laser stripes formed overlying the semipolar surface, wherein;

each of the laser stripes is characterized by a cavity orientation substantially parallel to the projection of a c-direction, each of the laser stripes having a length less than 300 μ

m;

each of the laser stripes is characterized by a width ranging from about 0.5 μ

m to about 2.5 μ

m;

each of the laser stripes is configured to operate in a single lateral mode;

each of the laser stripes is configured to emit a laser beam characterized by a first polarization state and a second polarization state, wherein the first polarization state is orthogonal to the second polarization state; and

the laser device is configured to emit a plurality of laser beams, each of the plurality of laser beams characterized by a primary polarization state and a secondary polarization state, wherein a power emitted in the second polarization state is at less than 15% of a power emitted in the first polarization state, and the laser device is characterized by an internal loss of less than 9 cm<sup>−

1</sup> and a polarization ratio of at least 90% or at least 95% between the power emitted in the first polarization state and the power emitted in the second polarization state.

13. The laser device of claim 12, wherein the laser stripe region is characterized by a length less than 200 μ

m, less than 100 μ

m, or less than 50 μ

m.

14. The laser device of claim 12, wherein each of the laser stripe regions has a first end having a first facet and a second end having a second facet, and wherein the first facet and the second facet are formed by a scribing and breaking process.

15. The laser device of claim 12, wherein each of the laser stripe regions has a first end having a first facet and a second end having a second facet wherein the first facet and the second facet are formed by an etching process;

wherein the etching process is selected from reactive ion etching (RIE), inductively coupled plasma (ICP) etching, and chemical assisted ion beam etching (CAIBE).

16. The laser device of claim 12, wherein the offcut of the semipolar orientation is between +/−

5 degrees toward a c-plane, between +/−

10 degrees toward an a-plane, or between +/−

5 degrees toward a c-plane and between +/−

10 degrees toward an a-plane.

17. The laser device of claim 12, wherein the laser device is configured to emit in a polarized state wherein the power emitted in the second polarization state is less than 10%, less than 5%, less than 1%, less than 0.1%, or less than 0.01%, the power emitted in the first polarization state.

18. The laser device of claim 12, wherein the width ranging from 1.3 μ

m to 2 μ

m and is configured to maintain a single lateral mode operation; and

wherein N ranges from 2 to 20.

19. The laser device of claim 12, wherein each pair of laser stripes is laterally spaced by about 3 μ

m to about 200 μ

m; and

further comprising a common p-type electrode region coupling the array of N laser stripes; and

a common n-type electrode coupling the array of N laser stripes.

20. The laser device of claim 12, further comprising an optical coupling device to optically couple an emission from each of the N laser stripes to form a single emission.

21. The laser device of claim 12, further comprising a total output power of at least 100 mW and characterized by a single lateral mode of operation of each of the N laser stripes.

22. The laser device of claim 12, further comprising a total output power of at least 200 mW and characterized by a single lateral mode of operation of each of the N laser stripes.

23. The laser device of claim 12, further comprising a total output power of at least 500 mW and characterized by a single lateral mode of operation of each of the N laser stripes.

24. The laser device of claim 12, wherein the laser device is operable to emit electromagnetic radiation in a wavelength range selected from a 400 nm to 435 nm range, a 435 nm to 480 nm range, a 480 nm to 505 nm range, and a 505 nm to 550 nm range.

25. The laser device of claim 12, wherein each of the laser stripe regions is configured to emit a linearly polarized laser beam, a circularly polarized laser beam, an elliptically polarized laser beam, or a combination of any of the foregoing.

26. A laser device comprising:

a gallium and nitrogen containing material having a semipolar surface configured on an offcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51), a (40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a (30-32) plane;

a laser stripe region formed overlying a portion of the semipolar surface, the laser stripe region being characterized by a cavity orientation substantially parallel to the projection of the c-direction, the laser stripe region having a first end and a second end;

a first facet provided on the first end of the laser stripe region;

a second facet provided on the second end of the laser stripe region;

an n-type cladding region overlying the semipolar surface;

an active region comprising at least one active layer region overlying the n-type cladding region;

the active region comprising a quantum well region or a double hetero-structure region; and

a p-type cladding region overlying the active region;

a width characterizing the laser stripe region configured to emit a laser beam having a first polarization state and a second polarization state, the first polarization state being orthogonal to the second polarization state and the first polarization state being the primary polarization state, the width configured to emit the laser beam operable in a multi-lateral mode for an internal loss of less than 8 cm<sup>−

1</sup>; and

a polarization ratio of the laser beam characterizing a cross-polarized emission such that at least 15% of an emitted power is in the second polarization state.

27. The laser device of claim 26, wherein the offcut of the semipolar orientation is between +/−

5 degrees toward a c-plane, between +/−

10 degrees towards an a-plane, or between +/−

5 degrees toward a c-plane and between +/−

10 degrees towards an a-plane;

wherein at least 20% of the emission is in the second polarization state or wherein at least 30% of the emission is in the second polarization state or wherein at least 40% of the emission is in the second polarization state.

28. The laser device of claim 27, wherein the laser device is configured to emit electromagnetic radiation in a wavelength range selected from a 400 nm to 435 nm range, a 435 nm to 480 nm range, a 480 nm to 505 nm range, and a 505 nm to 550 nm range.

29. The laser device of claim 27, wherein the laser stripe region is configured to emit a linearly polarized laser beam, a circularly polarized laser beam, or an elliptically polarized laser beam.

30. A method of manufacturing an optical device, the method comprising:

providing a gallium and nitrogen containing semipolar member having a crystalline surface region;

the semipolar surface being configured on an offcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51) plane, a (40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a (30-32) plane;

the gallium and nitrogen containing substrate member characterized by a dislocation density of less than 10⁷ cm<sup>−

2</sup>;

forming a gallium and nitrogen containing n-type cladding layer overlying the surface region, the n-type cladding layer having a thickness from 300 nm to 6000 nm with an n-type doping level of 1E17 cm<sup>−

3</sup> to 6E18 cm<sup>−

3</sup>;

forming an n-side separate confining heterostructure (SCH) waveguiding layer overlying the n-type cladding layer, the n-side SCH waveguide layer comprising gallium, indium, and nitrogen with a molar fraction of InN of between 1% and 12% and having a thickness from 20 nm to 150 nm;

forming an active region overlying the n-side SCH waveguiding layer, the active region comprising at least two quantum wells, the at least two quantum wells comprising InGaN with a thickness of about 2 nm to about 8 nm;

the at least two quantum wells separated by barrier regions, the barrier regions comprising gallium and nitrogen with a thickness of about 2.5 nm to about 25 nm;

forming a p-type gallium and nitrogen containing cladding layer overlying the active region, the p-type cladding layer having a thickness from 300 nm to 1000 nm with a p-type doping level of 1E17 cm<sup>−

3</sup> to 5E19 cm<sup>−

3</sup>;

forming a p++ gallium and nitrogen containing contact layer overlying the p-type cladding layer, the p++ gallium and nitrogen containing contact layer having a thickness from 10 nm to 120 nm with a p-type doping level of 1E19 cm<sup>−

3</sup> to 1E22 cm<sup>−

3</sup>; and

forming a waveguide member overlying the p++ gallium and nitrogen contact layer, the waveguide member aligned substantially in the projection of the c-direction, the waveguide member comprising a first end and a second end, the first end having a first facet and the second end having a second facet, the waveguide member being characterized by a length of less than 300 microns and a width configured to emit a laser beam having a selected ratio of a first polarization state and a second polarization state, the width configured to emit the laser beam operable in a single lateral mode for an internal loss of less than 8 cm<sup>−

1</sup>.

31. A method for manufacturing an optical device, the method comprising:

providing a gallium and nitrogen containing semipolar member having a crystalline surface region, the semipolar surface being configured on an offcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51) plane, a (40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a (30-32) plane, the gallium and nitrogen containing semipolar member being characterized by a dislocation density of less than 10⁷ cm<sup>−

2</sup>;

forming an n-type cladding layer comprising a first ternary AlGaN alloy or a first quaternary AlInGaN alloy, the first alloy comprising at least an aluminum bearing species, a gallium bearing species, and a nitrogen bearing species overlying the surface region, the n-type cladding layer having a thickness from 100 nm to 6000 nm with an n-type doping level of 5E16 cm<sup>−

3</sup> to 6E18 cm<sup>−

3</sup>;

forming an n-side separate confining heterostructure (SCH) waveguiding layer overlying the n-type cladding layer, the n-side SCH waveguiding layer comprising InGaN with a molar fraction of InN of between 1% and 10% and having a thickness from 30 nm to 150 nm;

forming a multiple quantum well active region overlying the n-side SCH waveguiding layer, the multiple quantum well active region comprising two to five, 2 nm to 8 nm thick, InGaN quantum wells separated by 3 nm to 20 nm thick gallium and nitrogen containing barrier layers;

forming a p-type cladding layer comprising a second ternary AlGaN alloy or quaternary AlInGaN alloy overlying the multiple quantum well active region, the p-type cladding layer having a thickness from 250 nm to 1,000 nm and comprising a p-type doping species including magnesium at a concentration of 1E17 cm<sup>−

3</sup> to 4E19 cm<sup>−

3</sup>;

forming a p++ gallium and nitrogen containing contact layer overlying the p-type cladding layer, the p++ gallium and nitrogen containing contact layer having a thickness from 10 nm to 140 nm and comprising a p-type doping species including magnesium at a concentration of 1E19 cm<sup>−

3</sup> to 1E22 cm<sup>−

3</sup>; and

forming a waveguide member, the waveguide member being aligned substantially in the projection of the c-direction, the waveguide member comprising of a first end and a second end, the first end comprising a first facet, the second end comprising a second facet, the waveguide member provided between the first facet and the second facet and being characterized by a length of less than 300 microns and a width configured to emit a laser beam having a selected ratio of a first polarization state and a second polarization state, the width configured to emit the laser beam operable in a single lateral mode for an internal loss of less than 8 cm<sup>−

1</sup>, the waveguide member having a first edge region formed on a first side of the waveguide member, the first edge region having a first etched surface formed on the first edge region, the waveguide member having a second edge region formed on a second side of the waveguide member, the second edge region having a second etched surface formed on the second edge region.

32. A method of manufacturing an optical device, the method comprising:

providing a gallium and nitrogen containing semipolar member having a crystalline surface region;

the semipolar surface being configured on an offcut orientation to one of either a (60-6-1) plane, a (60-61) plane, a (50-5-1) plane, a (50-51) plane, a (40-4-1) plane, a (40-41) plane, a (30-3-1) plane, a (30-31) plane, a (20-2-1) plane, a (20-21) plane, a (30-3-2) plane, or a (30-32) plane;

the gallium and nitrogen containing semipolar member characterized by a dislocation density of less than 10⁷ cm<sup>−

2</sup>;

forming a gallium and nitrogen containing n-type cladding layer overlying the surface region, the n-type cladding layer having a thickness from 300 nm to 6000 nm with an n-type doping level of 1E17 cm<sup>−

3</sup> to 6E18 cm<sup>−

3</sup>, the n-type cladding layer being substantially free from an aluminum bearing material;

forming an n-side separate confining heterostructure (SCH) waveguiding layer overlying the n-type cladding layer, the n-side SCH waveguiding layer comprising gallium, indium, and nitrogen with a molar fraction of InN of between 1% and 12% and having a thickness from 20 nm to 150 nm;

forming an active region overlying the n-side SCH waveguiding layer, the active region comprising at least two quantum well regions, the at least two quantum wells comprising InGaN with a thickness of about 2 nm to about 8 nm;

the at least two quantum wells separated by barrier regions, the barrier regions comprising least gallium and nitrogen with a thickness of about 2.5 nm to about 25 nm;

forming a p-type gallium and nitrogen containing cladding layer overlying the active region, the p-type cladding layer having a thickness from 300 nm to 1000 nm with a p-type doping level of 1E17 cm<sup>−

3</sup> to 5E19 cm<sup>−

3</sup>;

forming a p++ gallium and nitrogen containing contact layer overlying the p-type gallium and nitrogen containing cladding layer, the p++ gallium and nitrogen containing contact layer having a thickness from 10 nm to 120 nm with a p-type doping level of 1E19 cm<sup>−

3</sup> to 1E22 cm<sup>−

3</sup>; and

forming a waveguide member, the waveguide member aligned substantially in the projection of the c-direction, the waveguide member comprising a first end and a second end, the first end having a first facet and the second end having a second facet, the waveguide member being characterized by a length of less than 300 microns and a width configured to emit a laser beam having a selected ratio of a first polarization state and a second polarization state, the width configured to emit the laser beam operable in a single lateral mode for an internal loss of less than 8 cm<sup>−

1</sup>.