Semiconductor light emitting device and method for manufacturing the same

Abstract

A semiconductor light emitting device comprises a semiconductor multilayer film including an active layer for generating light, a p electrode formed on the semiconductor multilayer film, and a plasmon generating layer, which are provided on a substrate. A portion of the semiconductor multilayer film including at least the active layer forms a plurality of rods. The plasmon generating layer (8) fills between each rod. The plasmon generating layer (8) is formed of a material having a negative dielectric constant at the wavelength of emitted light. The rods are arranged in a periodic manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a semiconductor light emitting device according to a first embodiment of the present invention. FIG. 1B is a cross-sectional view of the semiconductor light emitting device of the first embodiment, taken along a line passing through an n electrode. FIG. 1C is a perspective view of the semiconductor light emitting device of the first embodiment, where a plasmon generating layer and an insulating layer are not illustrated.

FIG. 2A is a graph showing a dispersion relation between a frequency ω and a horizontal wave number k_// of surface plasmons in the semiconductor light emitting device of the first embodiment. FIG. 2B is a graph showing a relation between the frequency ω and a state density of surface plasmons.

FIG. 3 is a graph showing the result of calculation of a relation between the frequency ω and a conversion efficiency η_e-s from electron-positive hole pairs to surface plasmons in the semiconductor light emitting device.

FIG. 4 is a graph showing the result of calculation of τ_loss in the semiconductor light emitting device, where an interface of the plasmon generating layer and the insulating layer is approximated as being even.

FIG. 5 is a graph showing the result of calculation of η_s-p in the semiconductor light emitting device, where an active layer having an internal quantum efficiency of 30% was used.

FIGS. 6A and 6B are diagrams showing the results of theoretical calculation of the band structure of surface plasmons in the semiconductor light emitting device.

FIGS. 7A and 7B are diagrams showing the results of simulation of photon emission caused by surface plasmons in the semiconductor light emitting device. FIGS. 7C and 7D are diagrams showing electric field distributions at a metal/dielectric substance interface of surface plasmons in modes Γ4 and Γ2, respectively.

FIG. 8 is a graph showing the result of theoretical calculation of the state density of surface plasmons in the semiconductor light emitting device.

FIGS. 9A to 9G are cross-sectional views illustrating a method for manufacturing the semiconductor light emitting device of the first embodiment.

FIG. 10A is a perspective view of a semiconductor light emitting device according to a second embodiment of the present invention. FIG. 10B is a cross-sectional view of the semiconductor light emitting device, taken along a line passing through an n electrode. FIG. 10C is a perspective view of the semiconductor light emitting device of the second embodiment, where a plasmon generating layer and an insulating layer are not illustrated.

FIGS. 11A to 11D are cross-sectional views illustrating a method for manufacturing the semiconductor light emitting device of the second embodiment.

FIG. 12 is a cross-sectional view of a semiconductor light emitting device according to a third embodiment of the present invention.

FIG. 13 is a diagram illustrating a step of arranging microspheres on a semiconductor multilayer film in which an unevenness is formed, in a manufacturing process of the semiconductor light emitting device of the third embodiment.

FIG. 14A is a perspective view of a semiconductor light emitting device according to a fourth embodiment of the present invention. FIG. 14B is a cross-sectional view of the semiconductor light emitting device, taken along a line passing through an n electrode.

FIG. 15 is a cross-sectional view of a semiconductor light emitting device according to a fifth embodiment of the present invention.

FIGS. 16A to 16C are cross-sectional views illustrating a method for manufacturing the semiconductor light emitting device of the fifth embodiment.

FIG. 17A is a diagram for describing surface plasmons. FIG. 17B is a graph for describing surface plasmons.

FIG. 18 is a schematic diagram of a conventional LED employing surface plasmons.

Claims

1. A semiconductor light emitting device comprising: a semiconductor multilayer film including an active layer, wherein unevenness is formed in a portion including at least the active layer; anda plasmon generating layer made of a substance having a negative dielectric constant at a frequency of light generated, and buried in the unevenness.

2. The semiconductor light emitting device of claim 1, wherein a plurality of holes penetrating through the active layer are formed in the semiconductor multilayer film, and the plasmon generating layer is buried in the plurality of holes.

3. The semiconductor light emitting device of claim 2, wherein the plurality of holes are provided and arranged in a one-dimensional periodic manner or in a two-dimensional periodic manner.

4. The semiconductor light emitting device of claim 2, further comprising: a p electrode provided on the semiconductor multilayer film, wherein the plurality of holes are formed in the p electrode; andan n electrode contacting the semiconductor multilayer film,wherein a portion of an upper surface of the p electrode contacts the plasmon generating layer.

5. The semiconductor light emitting device of claim 4, wherein the n electrode is provided on a rear surface of the semiconductor multilayer film.

6. The semiconductor light emitting device of claim 1, wherein a plurality of rods including the active layer are formed in the semiconductor multilayer film, and the plasmon generating layer is buried between the plurality of rods.

7. The semiconductor light emitting device of claim 6, wherein the plurality of rods are provided and arranged in a one-dimensional periodic manner or in a two-dimensional periodic maimer.

8. The semiconductor light emitting device of claim 6, further comprising: a p electrode provided on each of the plurality of rods of the semiconductor multilayer film; andan n electrode contacting the semiconductor multilayer film,wherein an upper surface of the p electrode contacts the plasmon generating layer.

9. The semiconductor light emitting device of claim 8, wherein the n electrode is provided on a rear surface of the semiconductor multilayer film.

10. The semiconductor light emitting device of claim 1, further comprising: an insulating layer provided between a region of the semiconductor multilayer film in which the unevenness is formed, and the plasmon generating layer.

11. The semiconductor light emitting device of claim 10, wherein the insulating layer has a film thickness of 100 nm or less.

12. The semiconductor light emitting device of claim 1, wherein the plasmon generating layer has: a first plasmon generating layer made of a first material; anda second plasmon generating layer made of a second material different from the first material and provided on the first plasmon generating layer.

13. The semiconductor light emitting device claim 1, further comprising: a mounting substrate; andan adhesion layer for adhering a major surface of the mounting substrate and an upper surface of the plasmon generating layer together.

14. The semiconductor light emitting device of claim 1, further comprising: a substrate provided below the semiconductor multilayer film and transparent to light generated in the active layer.

15. The semiconductor light emitting device of claim 1, wherein, in an energy-horizontal wave number function of a plasmon generated in the plasmon generating layer, an energy when a horizontal wave number is 0 is substantially equal to a band gap energy of the active layer.

16. A semiconductor light emitting device comprising: a semiconductor multilayer film including an active layer, wherein unevenness is formed in a portion including at least the active layer;a microsphere made of a substance having a negative dielectric constant at a frequency of light generated, and buried in the unevenness; anda metal layer provided on the semiconductor multilayer film.

17. The semiconductor light emitting device of claim 16, wherein an outer shape of the microsphere is in the shape of a sphere, an ellipse or a rode.

18. The semiconductor light emitting device of claim 17, wherein the microsphere is hollow.

19. The semiconductor light emitting device of claim 17, wherein the microsphere includes a substance having a negative dielectric constant at the frequency of the light.

20. A method for manufacturing a semiconductor light emitting device, comprising the steps of: (a) forming a semiconductor multilayer film including an active layer, wherein unevenness is formed in a portion including at least the active layer; and(b) forming a plasmon generating layer made of a substance having a negative dielectric constant at a frequency of light generated, and buried in the unevenness.

21. The method of claim 20, further comprising, after the step (a): (c) forming an insulating layer on a region of the semiconductor multilayer film in which the unevenness is formed.

22. The method of claim 21, wherein, in the step (c), the insulating layer is formed by oxidation of the region of the semiconductor multilayer film in which the unevenness is formed.

23. The method of claim 20, further comprising, after the step (b): (d) removing the substrate from the semiconductor multilayer film.

24. The method of claim 20, further comprising, after the step (b): (e) adhering the plasmon generating layer onto the mounting substrate.

25. The method of claim 24, further comprising, after the step (e): (f) dividing the mounting substrate into pieces.

26. A method for manufacturing a semiconductor light emitting device, comprising the steps of: (a) forming a semiconductor multilayer film including an active layer, wherein unevenness is formed in a portion including at least the active layer;(b) placing the substrate in a solution in which a microsphere made of a substance having a negative dielectric constant at a frequency of light generated is dispersed, thereby burying the microsphere in the unevenness; and(c) forming a metal layer provided on the semiconductor multilayer film.

27. The method of claim 26, wherein, in the step (a), a plurality of holes penetrating through the active layer or a plurality of rods including the active layer are formed in the semiconductor multilayer film.