Semiconductor light emitting device

• US 20060038191A1
• Filed: 08/03/2005
• Published: 02/23/2006
• Est. Priority Date: 08/20/2004
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ueda, Tetsuzo, Onishi, Toshikazu, Tanigawa, Tatsuya
• Granted Patent: US 7,538,357 B2
• Time in Patent Office: Days
• US Class Current: 257/96
• CPC Class Codes: H01L 33/105 with a resonant cavity structure
• CPC Class Codes: H01L 33/465 with a resonant cavity structure
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: H01S 5/06226 Modulation at ultra-high frequencies
• CPC Class Codes: H01S 5/18311 using selective oxidation
• CPC Class Codes: H01S 5/18319 comprising a periodical structure in lateral directions
• CPC Class Codes: H01S 5/18355 having a defined polarisation
• CPC Class Codes: H01S 5/18358 containing spacer layers to adjust the phase of the light wave in the cavity
• CPC Class Codes: H01S 5/18386 Details of the emission surface for influencing the near- or far-field, e.g. a grating on the surface
• CPC Class Codes: H01S 5/18394 Apertures, e.g. defined by the shape of the upper electrode

Abstract

A semiconductor light emitting device includes: a cavity including a mesa formed over a substrate, the mesa having an active layer and being isolated by a recess formed around the mesa; and a resin layer with which the recess is filled. On the upper surface of the cavity, which is a light output surface through which light emitted from the active layer is output, a metal film having an opening whose diameter is smaller than the emission wavelength of the emitted light is formed.

Claims

1. A semiconductor light emitting device comprising:

a cavity including a mesa formed over a substrate, the mesa having an active layer and being isolated by a recess formed around the mesa;

a resin layer with which the recess is filled; and

a metal film formed over a light output surface of the cavity and having an opening formed therein,

wherein light emitted from the active layer is output through the light output surface, and the opening has a diameter smaller than an emission wavelength of the emitted light.

2. The device of claim 1, wherein two or more said openings are formed and arranged periodically.

3. The device of claim 1, wherein the diameter of the opening is smaller than or equal to one-half of the emission wavelength.

4. The device of claim 1, wherein the light output through the light output surface is a laser beam, and

in the laser beam, the value of a ratio of intensity of a TM wave component to intensity of a TE wave component is greater than or equal to two.

5. The device of claim 2, wherein in the metal film, the openings are arranged in a lattice.

6. The device of claim 5, wherein relation in P=λ

×

(i²+j²)^0.5/(ε

₁ε

₂/(ε

₁+ε

₂))^0.5 is satisfied where P is an opening period of the openings, ε

₁ is a dielectric constant of the metal film, ε

₂ is a dielectric constant of a material of a layer that is in contact with the metal film, and i and j are integers that are not negative.

7. The device of claim 5, wherein in the metal film, the openings are arranged in a triangular lattice or a hexagonal lattice.

8. The device of claim 1, wherein a planar shape of the opening is anisotropic.

9. The device of claim 1, wherein the metal film has a thickness of from 100 nm to 500 nm.

10. The device of claim 1, wherein the metal film is made of silver, gold, or aluminum.

11. The device of claim 1, wherein the metal film is formed of two layers made of different materials.

12. The device of claim 11, wherein of the two layers of the metal film, the upper layer is thinner than the lower layer, and

the lower layer is made of silver, gold, or aluminum.

13. The device of claim 11, wherein of the two layers of the metal film, the lower layer is made of silver and the upper layer is made of gold.

14. The device of claim 1, further comprising an intermediate layer formed on a surface of the metal film which is located closer to the active layer.

15. The device of claim 14, wherein the intermediate layer has a thickness for correcting phase change caused when the emitted light is reflected by the metal film.

16. The device of claim 15, wherein relation in 0.6×

λ

/n×

(¼

+½

i)≦

d≦

λ

/n×

(¼

+½

i) is satisfied where d is the thickness of the intermediate layer, n is a refractive index of the intermediate layer, λ

is the wavelength of the emitted light, and i is an integer that is not negative.

17. The device of claim 14, wherein the intermediate layer is a dielectric film.

18. The device of claim 17, wherein the dielectric film is a single-layer film made of one element, or a multilayer film made of two or more elements, the one element and the two or more elements being selected from the group consisting of silicon oxide, silicon nitride, aluminum oxide, titanium oxide, and tantalum oxide.

19. The device of claim 14, wherein the intermediate layer is a transparent conductive film.

20. The device of claim 19, wherein the transparent conductive film is made of indium tin oxide, zinc oxide, or tin oxide.

21. The device of claim 14, wherein the intermediate layer is a semiconductor multilayer film.

22. The device of claim 1, further comprising two reflectors provided to a side of the active layer which is located closer to the light output surface and to a side of the active layer which is located opposite to the light output surface,

wherein the metal film functions as the reflector provided to the side closer to the light output surface.

23. The device of claim 22, wherein the reflector provided to the side closer to the light output surface includes a first semiconductor multilayer film formed on a surface of the metal film which is located closer to the active layer.

24. The device of claim 23, wherein the number of periods in the first semiconductor multilayer film is adjusted according to a reflectivity of the metal film.

25. The device of claim 23, wherein the number of periods in the first semiconductor multilayer film is from nine to twenty-two.

26. The device of claim 22, wherein the reflectors have a reflectivity of from 99.4% to 99.9%.

27. The device of claim 22, wherein the reflector provided to the side opposite to the light output surface is formed of a second semiconductor multilayer film.

28. The device of claim 14, further comprising an upper layer formed on a surface of the metal film which opposes the surface of the metal film that is located closer to the active layer.

29. The device of claim 1, further comprising:

a first protective layer formed between the resin layer and side and bottom faces of the recess;

a second protective layer for covering an upper surface of the resin layer; and

an electrode, formed on the second protective layer, for injecting current into the active layer.

30. The device of claim 29, wherein the resin layer is completely surrounded by the first and second protective layers.

31. The device of claim 29, wherein the first and second protective layers are each made of SiO₂, SiN, SiON, Nb₂O₅, ZrO₂, or Ta₂O₅.

32. The device of claim 29, wherein at least part of the resin layer is located higher than an upper surface of the mesa.

33. The device of claim 29, wherein the upper surface of the resin layer and an upper surface of the mesa are connected with no level difference formed therebetween.

34. The device of claim 29, wherein a relative dielectric constant of the resin layer is smaller than or equal to three.

35. The device of claim 34, wherein the resin layer is made of benzocyclobutene resin.

36. The device of claim 1, further comprising a current confinement layer provided in the mesa between the active layer and the metal film and including a high-resistance region and a current confinement region, the high-resistance region being a selectively oxidized region or a region into which protons have been injected selectively, the current confinement region being surrounded by the high-resistance region.

37. The device of claim 36, wherein the current confinement region has a diameter of 10 μ

m or smaller.

38. The device of claim 1, wherein the diameter of the mesa is adjusted so that the volume of the mesa is greater than or equal to one-half of the volume of the entire device.

39. The device of claim 29, wherein the side faces of the mesa are inclined.