(Al,Ga,In)N diode laser fabricated at reduced temperature

• US 9,054,498 B2
• Filed: 06/18/2014
• Issued: 06/09/2015
• Est. Priority Date: 06/17/2005
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Cohen, Daniel A., DenBaars, Steven P., Nakamura, Shuji
• Primary Examiner(s): TOBERGTE, NICHOLAS J
• Application Number:
  US14/308,445
• Publication Number:
  US 20140301419A1
• Time in Patent Office: 356 Days
• Field of Search: 257/98, 438/22
• US Class Current: 1/1
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 2304/04 MOCVD or MOVPE
• CPC Class Codes: H01S 2304/12 Pendeo epitaxial lateral overgrowth [ELOG], e.g. for growing GaN based blue laser diodes
• CPC Class Codes: H01S 5/0215 Bonding to the substrate
• CPC Class Codes: H01S 5/0217 Removal of the substrate
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/2054 Methods of obtaining the confinement
• CPC Class Codes: H01S 5/22 having a ridge or stripe structure
• CPC Class Codes: H01S 5/3013 AIIIBV compounds
• CPC Class Codes: H01S 5/3211 characterised by special cladding layers, e.g. details on band-discontinuities
• CPC Class Codes: H01S 5/3213 asymmetric clading layers
• CPC Class Codes: H01S 5/3214 comprising materials from other groups of the Periodic Table than the materials of the active layer, e.g. ZnSe claddings and GaAs active layer
• 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 of fabricating an (Al,Ga,In)N laser diode, comprising depositing one or more III-N layers upon a growth substrate at a first temperature, depositing an indium containing laser core at a second temperature upon layers deposited at a first temperature, and performing all subsequent fabrication steps under conditions that inhibit degradation of the laser core, wherein the conditions are a substantially lower temperature than the second temperature.

Claims

1. A method of fabricating a III-Nitride diode laser, the method comprising:

forming a III-Nitride layer on or above a growth substrate, wherein the III-Nitride layer is formed, using at least deposition, at a first temperature, and wherein the III-Nitride layer comprises an indium-containing active region; and

performing at least one subsequent fabrication process at a second temperature that is lower than the first temperature to inhibit degradation of the indium-containing active region, wherein the subsequent fabrication process comprise forming a conducting oxide waveguide or cladding layer on or above the III-Nitride layers at the second temperature.

2. The method of claim 1, wherein the conducting oxide waveguide or cladding layer comprises a crystalline transparent conductive oxide layer grown from an aqueous solution.

3. The method of claim 1, wherein the conducting oxide waveguide or cladding layer comprises a combination of a crystalline transparent conductive oxide layer grown from an aqueous solution and an amorphous or polycrystalline transparent conducting oxide layer deposited by physical vapor deposition.

4. The method of claim 1, wherein the conducting oxide waveguide or cladding layer comprises an amorphous or polycrystalline transparent conducting oxide formed by physical vapor deposition.

5. The method of claim 1, wherein the conducting oxide waveguide or cladding layer comprises a crystalline transparent conductive oxide layer wafer bonded on or above the III-Nitride layer.

6. The method of claim 1, wherein the conducting oxide waveguide or cladding layer is deposited by a method other than crystal growth at a temperature above 550°

C.

7. The method of claim 1, wherein the conducting oxide waveguide or cladding layer has a bulk resistivity below 10 Ohm-centimeters (Ohm-cm) and is capable of making an electrical contact to the indium-containing active region with a specific contact resistance below 0.01 Ohm-cm².

8. The method of claim 1, wherein the conducting oxide waveguide or cladding layer has an optical absorption coefficient below 2000 cm⁻

1 measured at a diode laser'"'"'s wavelength.

9. The method of claim 1, wherein the conducting oxide waveguide or cladding layer has a refractive index lower than a refractive index of the indium-containing active region.

10. The method of claim 1, wherein the conducting oxide waveguide or cladding layer is comprised of one or more metal oxides selected from a group including tin oxide, zinc oxide, gallium oxide, magnesium oxide, cadmium oxide, and alloys thereof.

11. The method of claim 1, wherein the conducting oxide waveguide or cladding layer is patterned to form a rib or ridge, to serve as a lateral waveguide.

12. The method of claim 1, wherein the III-Nitride layers further comprise one or more barrier layers, waveguide layers, cladding layers, blocking layers, or injection layers.

13. The method of claim 1, wherein:

the indium-containing active region is grown on or above a III-Nitride lower injection layer, and the III-Nitride lower injection layer serves to inject either electrons or holes into the indium-containing active region;

the indium-containing active region comprises;

at least one indium-containing active layer in which the light is generated; and

one or more III-Nitride confinement layers, adjacent to each side of the indium-containing active layer, serving to confine the electrons and holes;

at least one III-Nitride upper injection layer is grown on or above the indium-containing active region, serving as an upper injection layer for carriers of a type not provided by the lower injection layer; and

at least one first III-Nitride blocking layer is grown between the indium-containing active region and the lower injection layer, or at least one second III-Nitride blocking layer is grown between the indium-containing active region and the upper injection layer, or the first III-Nitride blocking layer and the second III-Nitride blocking layer, wherein;

the first III-Nitride blocking layer serves to prevent injection of first minority carriers into the lower injection layer and the first minority carriers are carriers of the type not provided by the lower injection layer, and

the second III-Nitride blocking layer serves to prevent injection of second minority carriers into the upper injection layer and the second minority carriers are carriers of a type not provided by the upper injection layer.

14. A III-Nitride diode laser, comprising:

a III-Nitride layer formed on or above a growth substrate, wherein the III-Nitride layer is formed at a first temperature, and wherein one or more of the III-Nitride layers comprise an indium-containing active region; and

a conducting oxide waveguide or cladding layers formed on or above the III-Nitride layers at a second temperature that is lower than the first temperature to inhibit degradation of the indium-containing active region.

15. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer comprises a crystalline transparent conductive oxide layer grown from an aqueous solution.

16. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer comprises a combination of a crystalline transparent conductive oxide layer grown from an aqueous solution and an amorphous or polycrystalline transparent conducting oxide layer deposited by physical vapor deposition.

17. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer comprises an amorphous or polycrystalline transparent conducting oxide formed by physical vapor deposition.

18. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer comprises a crystalline transparent conductive oxide layer wafer bonded on or above the III-Nitride layer.

19. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer is deposited by a method other than crystal growth at a temperature above 550°

C.

20. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer has a bulk resistivity below 10 Ohm-centimeters (Ohm-cm) and is capable of making an electrical contact to the indium-containing active region with a specific contact resistance below 0.01 Ohm-cm².

21. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer has an optical absorption coefficient below 2000 cm⁻

1 measured at a diode laser'"'"'s wavelength.

22. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer has a refractive index lower than a refractive index of the indium-containing active region.

23. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer is comprised of one or more metal oxides selected from a group including tin oxide, zinc oxide, gallium oxide, magnesium oxide, cadmium oxide, and alloys thereof.

24. The laser of claim 14, wherein the conducting oxide waveguide or cladding layer is patterned to form a rib or ridge, to serve as a lateral waveguide.

25. The laser of claim 14, wherein the III-Nitride layers further comprise one or more barrier layers, waveguide layers, cladding layers, blocking layers, or injection layers.

26. The laser of claim 14, wherein:

the indium-containing active region is grown on or above a III-Nitride lower injection layer, and the III-Nitride lower injection layer serves to inject either electrons or holes into the indium-containing active region;

the indium-containing active region comprises;

at least one indium-containing active layer in which the light is generated; and

one or more III-Nitride confinement layers, adjacent to each side of the indium-containing active layer, serving to confine the electrons and holes;

at least one III-Nitride upper injection layer is grown on or above the indium-containing active region, serving as an upper injection layer for carriers of a type not provided by the lower injection layer; and

at least one first III-Nitride blocking layer is grown between the indium-containing active region and the lower injection layer, or at least one second III-Nitride blocking layer is grown between the indium-containing active region and the upper injection layer, or the first III-Nitride blocking layer and the second III-Nitride blocking layer, wherein;

the first III-Nitride blocking layer serves to prevent injection of first minority carriers into the lower injection layer and the first minority carriers are carriers of the type not provided by the lower injection layer, and

the second III-Nitride blocking layer serves to prevent injection of second minority carriers into the upper injection layer and the second minority carriers are carriers of a type not provided by the upper injection layer.