Semiconductor light emitting device
A semiconductor light emitting device includes a semiconductor light emitting portion having a first contact layer of a first conductivity, a second contact layer of a second conductivity and an active layer sandwiched between the first and second contact layers. The device further includes a transparent electrode which substantially entirely covers a surface of the second contact layer in ohmic contact with the surface of the second contact layer and is transparent to a wavelength of light emitted from the semiconductor light emitting portion, and a metal reflection film which is opposed to substantially the entire surface of the transparent electrode and electrically connected to the transparent electrode, and reflects the light emitted from the semiconductor light emitting portion and passing through the transparent electrode toward the semiconductor light emitting portion.
1. A semiconductor light emitting device comprising:
a semiconductor light emitting portion having a first contact layer of a first conductivity, a second contact layer of a second conductivity and an active layer sandwiched between the first and second contact layers;
a transparent electrode which substantially entirely covers a surface of the second contact layer in ohmic contact with the surface of the second contact layer and is transparent to a wavelength of light emitted from the semiconductor light emitting portion; and
a metal reflection film which is opposed to substantially the entire surface of the transparent electrode and electrically connected to the transparent electrode, and reflects the light emitted from the semiconductor light emitting portion and passing through the transparent electrode toward the semiconductor light emitting portion;
further comprising a transparent insulation film disposed between the transparent electrode and the metal reflection film, wherein
the metal reflection film is connected to the transparent electrode via an opening formed in the transparent insulation film; and
wherein the reflection film is provided on a surface portion of the transparent insulation film opposite from the semiconductor light emitting portion and substantially entirely covers a region of the transparent insulation film opposed to the semiconductor light emitting portion.
2. A semiconductor light emitting device as set forth in claim 1 , further comprising a transparent substrate which is transparent to the wavelength of the light emitted from the semiconductor light emitting portion, and has a light extracting surface defined by one surface thereof through which the light emitted from the semiconductor light emitting portion is extracted to the outside, and a device formation surface defined by the other surface thereof on which the semiconductor light emitting portion is provided, the device formation surface of the transparent substrate being opposed to the first contact layer.
3. A semiconductor light emitting device as set forth in claim 1 , further comprising an electrode portion extending from the first contact layer toward the metal reflection film.
4. A semiconductor light emitting device as set forth in claim 1 , wherein
the transparent electrode comprises a Zn 1-x Mg x O (wherein 0≦x<1) film.
5. A semiconductor light emitting device as set forth in claim 1 , wherein
the first contact layer has a light extracting surface defined by one surface thereof,
the device further comprising an electrode provided on the light extracting surface opposite from the transparent electrode.
6. A semiconductor light emitting device as set forth in claim 5 , wherein
the light extracting surface is a roughened surface.
7. A semiconductor light emitting device as set forth in claim 5 , wherein
the light extracting surface is a regularly undulated surface.
8. A semiconductor light emitting device as set forth in claim 5 , wherein
the first contact layer is a photonic crystal layer.
9. A semiconductor light emitting device as set forth in claim 1 , wherein the reflection of the light from the semiconductor light emitting portion occurs in an interface between the transparent insulation film and the metal reflection film.
10. A semiconductor light emitting device as set forth in claim 1 , wherein a ratio of the area of the opening formed in the transparent insulation film to an area of the transparent electrode is 1 to 30%.
11. A semiconductor light emitting device as set forth in claim 1 , wherein the thickness t of the transparent insulation film is t=λ/(4n)×(2m+1), where m is a zero or a positive integer, λis the wavelength of the light emitted from the semiconductor light emitting portion, and n is the refraction index of the transparent insulation film.
12. A semiconductor light emitting device as set forth in claim 1 , comprising a plurality of the opening formed in the transparent insulation film, which openings expose minute surface portion areas of the transparent electrode.
13. A semiconductor light emitting device as set forth in claim 1 , wherein the reflection film is connected to the transparent electrode via the opening formed in the transparent insulation film, whereby the transparent electrode and the reflective electrode are electrically connected.