Versatile method and system for single mode VCSELs

• US 6,905,900 B1
• Filed: 11/28/2000
• Issued: 06/14/2005
• Est. Priority Date: 11/28/2000
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Johnson, Ralph H., Morales, Gilberto
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Mondt, Johannes
• Application Number:
  US09/724,820
• Time in Patent Office: 1,659 Days
• Field of Search: 438/22, 438/29, 438/45, 372 43- 50, 372/96, 257 79-103
• US Class Current: 438/29
• CPC Class Codes: H01S 2301/166 Single transverse or lateral mode
• CPC Class Codes: H01S 5/18308 having a special structure for lateral current or light confinement
• CPC Class Codes: H01S 5/18311 using selective oxidation
• CPC Class Codes: H01S 5/18316 Airgap confined
• 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 5/18391 Aperiodic structuring to influence the near- or far-field distribution
• CPC Class Codes: H01S 5/2063 obtained by particle bombardment

Abstract

A system and method for providing a single mode VCSEL (vertical cavity surface emitting laser) component (100) is disclosed, comprising a semiconductor substrate (102) having a lower surface and an upper surface, a bottom electrical contact (104) disposed along the lower surface of the substrate, a lower mirror (106) formed of n-type material and disposed upon the upper surface of the substrate, an active region (108) having a plurality of quantum wells disposed upon the lower mirror portion, an upper mirror (110) formed from isotropic material and disposed upon the active region, an equipotential layer (112) disposed upon the upper mirror portion, a first upper electrical contact (120) disposed upon the equipotential layer, a second upper electrical contact (122) disposed upon the equipotential layer at a particular distance (124) from the first upper electrical contact, a first isolation region (126) disposed beneath the first upper contact and traversing the equipotential layer, the upper mirror, the active region, and the lower mirror, a second isolation region (128) disposed beneath the second upper contact and traversing the equipotential layer, the upper mirror, the active region, and the lower mirror, and an insulating layer (114, 116) interposed between the upper mirror and the equipotential layer and adapted to form therebetween an aperture (118) of smaller dimension than the particular distance between the first and second upper contacts.

Claims

1. A method of producing a single mode VCSEL comprising the steps of:

forming a VCSEL structure having a substrate, a bottom contact portion disposed below a lower surface of the substrate, a lower mirror portion disposed above an upper surface of the substrate, an active region disposed above the lower mirror portion, and an upper mirror portion disposed above the active region formed from an electrically isotropic material, the upper mirror portion having layers of a first mobility material and layers of a second mobility material, the first mobility being higher than the second mobility, wherein the layers of the first mobility material are doped less than the layers of the second mobility material except at graded interfaces between the first mobility material and the second mobility material when a doping level at the interfaces is graded so that the resistivity of the upper mirror portion is substantially independent of direction;

providing a substantially equipotential layer disposed above the upper mirror portion;

providing an electrically insulating layer between the upper mirror portion and the equipotential layer to form an aperture therebetween; and

providing an upper contact portion disposed above the equipotential layer.

2. The method of claim 1 wherein the substrate is formed of Gallium Arsenide material.

3. The method of claim 1 wherein the lower mirror portion is formed of a p-type material and the upper mirror portion is formed of a n-type material.

4. The method of claim 1 wherein the lower mirror portion is formed of a p-type material and the upper mirror portion is formed on a n-type material.

5. The method of claim 1 wherein the both the lower and upper mirror portion are formed of n-type material.

6. The method of claim 1 wherein the both the lower and upper mirror portions are formed of p-type material.

7. The method of claim 1 wherein the step of providing an equipotential layer further comprises providing a layer of material having a resistivity of 0.01 ohm-cm.

8. The method of claim 1 wherein the step of providing an equipotential layer further comprises providing a layer of Aluminum Gallium Arsenide.

9. The method of claim 1 wherein the insulating layer comprises an oxide.

10. The method of claim 9 wherein the insulating layer comprises Al₂O₃.

11. The method of claim 1 wherein the insulating layer comprises air.

12. The method of claim 1 wherein the step of providing an equipotential layer further comprises providing a layer of material having electrical conductance greater than the conductance of the upper mirror portion.

13. The method of claim 12 wherein the step of providing an equipotential layer further comprises providing a layer of material having conductance at least four times greater than the conductance of the upper mirror portion.

14. The method of claim 12 wherein the step of providing an equipotential layer further comprises providing a layer of material having conductance at least ten times greater than the conductance of the upper mirror portion.

15. The method of claim 1 wherein the step of forming a VCSEL structure further comprises forming the upper mirror portion of material having a lateral conductance that is substantially similar to the conductance in the vertical direction.

16. The method of claim 10 wherein the insulating layer is formed to reduce reflectivity outside the aperture.

17. The method of claim 10 wherein the insulating layer is formed to increase effective index outside the aperture and thereby produce a longer resonant wavelength outside the aperture.

18. The method of claim 10 wherein the insulating layer is formed to reduce reflectivity and to increase effective index outside the aperture.

19. A method of providing anti guide mode selectivity in a VCSEL comprising the steps of:

forming a VCSEL structure having a substrate, a bottom contact portion disposed below a lower surface of the substrate, a lower mirror portion disposed above an upper surface of the substrate, an active region disposed above the lower mirror portion, and an upper mirror portion disposed above the active region formed from an isotropic material, the upper mirror portion having layers of a first mobility material and layers of a second mobility material, the first mobility being higher than the second mobility, wherein the layers of the first mobility material are doped less than the layers of the second mobility material except at interfaces between the first mobility material and the second mobility material where a doping level at the interfaces is graded so that the resistivity of the upper mirror portion is substantially independent of direction;

providing a substantially equipotential layer disposed above the upper mirror portion;

providing an electrically insulating layer between the upper mirror portion and the equipotential layer to form an aperture therebetween, wherein the electrically insulating layer is adapted to provide a greater nominal cavity resonance outside the aperture than inside it; and

providing an upper contact portion disposed upon the equipotential layer.

20. A method of producing a single mode VCSEL comprising the steps of:

forming a VCSEL structure having a substrate, a bottom contact portion disposal below a lower surface of the substrate, a lower mirror portion disposed above an upper surface of the substrate, and active region disposed above the lower mirror portion, and an upper mirror portion disposed above the active region formed from electrically isotropic material, the upper mirror portion having layers of a first mobility material and layers of a second mobility material, the first mobility being higher than the second mobility, wherein the layers of the first mobility material are doped less than the layers of the second mobility material except at interfaces between the first mobility material and the second mobility material where a doping level at the interfaces is graded so that the resistivity of the upper mirror portion is substantially independent of direction and disposed upon to the active region;

providing a substantially equipotential layer disposed above the upper mirror portion;

providing an electrically insulating layer between the upper mirror portion and the equipotential layer to form an aperture therebetween, wherein the insulating layer is formed to reduce reflectivity and to increase effective index outside the aperture; and

providing an upper contact portion disposed above the equipotential layer.

21. A method for producing an optoelectronic device, the method comprising the steps of:

providing a lower mirror portion;

providing an active region above the lower mirror portion;

providing an upper mirror portion above the active region, the upper mirror portion having layers of higher mobility material and layers of lower mobility material, where the layers of higher mobility material have a lower doping level than the layers of lower mobility material except at graded interfaces between the layers of higher mobility material and the lower mobility where a doping level is heavier than the doping level of the layers of lower mobility material so that the resistivity of the upper mirror portion is substantially independent of direction;

providing a substantially equipotential portion above the upper mirror portion; and

providing an electrically insulating portion between the upper mirror portion and the equipotential portion, the electrically insulating portion forming an aperture.

22. The method of claim 21 wherein the substantially equipotential portion includes doped AIGaAs.

23. The method of claim 21 wherein the substantially equipotential portion has a resistivity of about 0.01 ohm-cm or less.

24. The method of claim 21 wherein the substantially equipotential portion providing step includes providing one or more layers of material that have an electrical conductance that is greater than the electrical conductance of the upper mirror portion.

25. The method of claim 24 wherein the substantially equipotential portion providing step includes providing one or more layers of material having an electrical conductance that is at least four times the electrical conductance of the upper mirror portion.

26. The method of claim 24 wherein the substantially equipotential portion providing step includes providing one or more layers of material having an electrical conductance that is at least ten times the electrical conductance of the upper mirror portion.

27. The method of claim 21 wherein the insulating portion is formed to reduce the reflectivity outside of the aperture.

28. The method of claim 21 wherein the insulating portion is formed to increase the effective index outside the aperture and thereby produce a longer resonant wavelength outside the aperture.

29. The method of claim 21 wherein the substantially equipotential portion is another mirror portion.

30. A method for producing an optoelectronic device, the method comprising the steps of:

providing a lower mirror portion;

providing an active region above the lower mirror portion;

providing an upper mirror portion above the active region, the upper mirror portion having layers of higher mobility material and layers of lower mobility material, wherein the layers of higher mobility material having a lower doping level than the layers of lower mobility material except at graded interfaces between the layers of higher mobility material and the lower mobility material where a dopine level is heavier than the doping level of the layers of lower mobility material so that the resistivity of the upper mirror portion is substantially independent of direction;

providing a substantially equipotential portion above the upper mirror portion; and

providing an electrically insulating portion within the upper mirror portion, the electrically insulating portion forming an aperture.

31. The method of claim 30 wherein the lower mirror portion is formed of a n-type material and the upper mirror portion is formed of a p-type material.

32. The method of claim 30 wherein the lower mirror portion is formed of a p-type material and the upper mirror portion is formed of a n-type material.

33. The method of claim 30 wherein the lower mirror portion and the upper mirror portion are formed from either an n-type of material or a p-type of material.

34. The method of claim 30 wherein the upper mirror portion includes a number of semi-conductor layers with interfaces therebetween, the method further comprising the step of doping the interfaces more heavily than selected non-interface regions.

35. The method of claim 30 further comprising the step of doping the upper mirror portion such that the product of the hole concentration and the mobility is substantially constant across at least a portion of the thickness of the upper mirror portion.

36. The method of claim 30 further comprising the step of providing a dielectric stack above the aperture.

37. The optoelectronic device of claim 30 further comprising a dielectric stack situated above the aperture.

38. A method of producing a single mode VCSEL comprising the steps of:

forming a VCSEL structure having a substrate, a bottom contact portion disposed below a lower surface of the substrate, a lower mirror portion disposed above an upper surface of the substrate, an active region disposed above the lower mirror portion, and an upper mirror portion disposed above the active region formed such that a product of a hole concentration and a mobility is substantially constant for each layer in the upper mirror portion;

providing a substantially equipotential layer disposed above the upper mirror portion, the substantially equipotential layer comprises a layer of semiconductor material;

providing an electrically insulating layer between the upper mirror portion and the equipotential layer to form an aperture therebetween; and

providing an upper contact portion disposed above the equipotential layer.

39. A method according to claim 38 wherein the substantially equipotential layer comprising a layer of Aluminum Gallium Arsenide.

40. A method for producing an optoelectronic device, the method comprising the steps of:

providing a lower mirror portion;

providing an active region above the lower mirror portion;

providing an upper mirror portion above the active region, the upper mirror having graded interfaces between layers in the upper mirror portion, wherein a product of a hole concentration and a mobility is substantially constant for each layer in the upper mirror portion;

providing a substantially equipotential portion above the upper mirror portion, wherein the substantially equipotential portion is another mirror portion; and

providing an electrically insulating portion between the upper mirror portion and the equipotential portion, the electrically insulating portion forming an aperture.

41. A method for producing an optoelectronics device, the method comprising the steps of:

providing a lower mirror portion;

providing an active region above the lower mirror portion;

providing an upper mirror portion above the active region, the upper mirror portion being at least substantially electrically isotropic;

doping the upper mirror portion such that the product of the hole concentration and the mobility is substantially constant across at least one or more semiconductor layers of the upper mirror portion, wherein doping at interfaces between semiconductor layers in the upper mirror portion is heavier than doping within the semiconductor layers;

providing a substantially equipotential portion above the upper mirror portion; and

providing an electrically insulating protein within the upper mirror portion and/or between the upper mirror portion and the equipotential portion, the electrically insulating portion forming an aperture.