Laser diodes with scribe structures

• US 9,142,935 B2
• Filed: 04/29/2014
• Issued: 09/22/2015
• Est. Priority Date: 09/17/2009
• Status: Active Grant

• Current Assignee: Kyocera SLD Laser Incorporated (Kyocera Corporation)
• Original Assignee: Soraa Laser Diode, Inc. (Kyocera Corporation)
• Inventors: Raring, James W., Pfister, Nick, Chang, Yu-Chia, Schmidt, Mathew C., Felker, Drew
• Primary Examiner(s): Rodriguez, Armando
• Application Number:
  US14/264,786
• Publication Number:
  US 20140315340A1
• Time in Patent Office: 511 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02016 Backside treatment
• CPC Class Codes: H01L 21/268 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 21/302 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
• CPC Class Codes: H01L 21/428 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/0062 for devices with an active region comprising only III-V compounds
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01S 2301/14 Semiconductor lasers with special structural design for lasing in a specific polarisation mode
• CPC Class Codes: H01S 5/0202 Cleaving
• CPC Class Codes: H01S 5/0206 Substrates, e.g. growth, shape, material, removal or bonding; specific crystal orientation H01S5/3202
• CPC Class Codes: H01S 5/0207 Substrates having a special shape
• CPC Class Codes: H01S 5/1039 Details on the cavity length
• 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 5/3063 using Mg
• CPC Class Codes: H01S 5/320275 semi-polar orientation
• 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 method and device for emitting electromagnetic radiation using semipolar or nonpolar gallium containing substrates is described where the backside of the substrate includes multiple scribes that reduce stray light leaking.

Claims

1. A method for fabricating an optical device, the method comprising:

providing a substrate having a front side and a back side, the substrate including gallium material;

forming an active region including at least one quantum well overlying the front side of the substrate;

forming a cavity overlying the active region, the cavity having a length and a width; and

forming a plurality of trenches provided on the back side of the substrate, at least a portion of each of the plurality of trenches extending under the cavity, the portion under the cavity extending non-parallel to the length of the cavity.

2. The method of claim 1 wherein the plurality of trenches extend across a width of the substrate and are configured to reduce a stray leakage light from the front surface of the substrate;

and reduce an interference pattern of the leakage light.

3. The method of claim 1 wherein:

the plurality of trenches is characterized by a length of about 30 to 100 um; and

the substrate is characterized by a width of about 50 to 500 um.

4. The method of claim 1 wherein the length of the cavity is substantially parallel to a c-direction.

5. The method of claim 1 wherein the substrate is characterized by a nonpolar orientation and the length of the cavity is substantially parallel to a c-direction.

6. The method of claim 1 wherein the substrate is characterized by a semi-polar orientation and the length of the cavity is substantially parallel to the projection of the c-direction.

7. The method of claim 1 wherein the plurality of trenches is characterized by a depth of at least 5 microns below the top side of the substrate.

8. The method of claim 1 wherein the plurality of trenches is characterized by a depth of at least 40 microns below the top side of the substrate.

9. The method of claim 1 wherein the plurality of trenches are oriented substantially perpendicular to the length of the cavity.

10. The method of claim 1 wherein the plurality of trenches are orientated at an angle of about 30 to 60 degrees to the length of the cavity.

11. The method of claim 1 wherein the plurality of trenches are substantially straight lines and are parallel to one another.

12. The method of claim 1 wherein:

the substrate is characterized by a thickness of at least 50 microns; and

the plurality of trenches are characterized by a depth of at least 5 microns less than the thickness of the substrate.

13. The method of claim 1 wherein:

the substrate is characterized by a thickness of at least 50 microns; and

the plurality of trenches are characterized by a depth of at least 10 microns less than the thickness of the substrate.

14. The method of claim 1 wherein the plurality of trenches are characterized by a width of about 0.1 to 10 microns.

15. The method of claim 1 wherein the substrate is characterized by a non-polar or semi-polar orientation.

16. The method of claim 1 wherein a laser diode including the active region fabricated on the substrate has an operational wavelength in the green wavelength regime of about 500-540 nm.

17. The method of claim 1 wherein a laser diode including the active region fabricated on the substrate has an operational wavelength in the blue wavelength regime of about 430-480 nm.

18. The method of claim 1 wherein a laser diode including the active region fabricated on the substrate has an operational wavelength in the violet wavelength regime of about 390-430 nm.

19. A method for fabricating an optical device comprising:

providing a gallium and nitrogen containing substrate, the substrate including a front side and a back side, the back side including a plurality of trench structures each having at least a portion that extends substantially straight, the plurality of trench structures being characterized by a first direction, the plurality of trench structures being configured to reduce a leakage light from the front surface of the substrate;

forming a laser stripe region overlying a portion of the substrate, the laser stripe region being characterized by a cavity orientation non-parallel to the first direction, the laser stripe region having a first end and a second end;

forming a first facet on the first end of the laser stripe region; and

forming a second facet on the second end of the laser stripe region.