Ultraviolet semiconductor light-emitting device and fabrication method

1. A UV semiconductor light-emitting device, comprising:

a light-emitting epitaxial layer having one side as a light-emitting surface and another side as a non-light-emitting surface and comprising an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer;

a tunneling junction at the non-light-emitting side and comprising a patterned structure having openings to expose the light-emitting epitaxial layer;

an optical phase matching layer over a surface layer of the light-emitting epitaxial layer and transmissive of UV light; and

a reflecting layer covering the tunneling junction and the optical phase matching layer.

2. The semiconductor light-emitting device of claim 1 , wherein the reflecting layer comprises a material having a work function of about 4.0-5.0 eV, and forms ohmic contact with the tunneling junction.

3. The semiconductor light-emitting device of claim 2 , wherein the reflecting layer has a work function value of about 4.0-5.0 eV, and a reflectivity of not less than 70% for light with wavelengths less than 380 nm.

4. The semiconductor light-emitting device of claim 1 , wherein the tunneling junction has a patterned structure and a side with a solid slope with a gradient between 10°-85°.

5. The semiconductor light-emitting device of claim 4 , wherein the patterned structure comprises at least one of a band shape, an island shape, a round platform, a trapezoid platform, a cone shape, or a hemispheric shape.

6. The semiconductor light-emitting device of claim 1 , wherein the light-emitting epitaxial layer comprises a III-V group material that is a binary compound or ternary compound comprising at least one of Al, Ga, N, P, or In.

7. The semiconductor light-emitting device of claim 6 , wherein the III-V group material is AlGaN having an Al concentration of not less than 40%.

8. The semiconductor light-emitting device of claim 1 , wherein: the optical phase matching layer is composed of an insulation material.

9. A method of fabricating a UV light-emitting device with wavelengths of about 100-380 nm, the method comprising:

(1) fabricating an n-type conductive layer, a light-emitting layer, a p-type conductive layer over a growth substrate and forming a light-emitting epitaxial layer having one side as a light-emitting surface and another side as a non-light-emitting surface;

(2) fabricating a tunneling junction over the non-light-emitting surface;

(3) patterning the tunneling junction including etching an area of the tunneling junction and the light-emitting epitaxial layer to expose a portion of the light-emitting epitaxial layer surface;

(4) fabricating an optical phase matching layer over the exposed light-emitting epitaxial layer surface; and

(5) fabricating a reflecting layer over the tunneling junction and the optical phase matching layer.

10. The fabrication method of claim 9 , wherein the growth substrate is substantially transparent and UV-permeable with a band gap not less than 3.4 eV.

11. The fabrication method of claim 9 , wherein the step (3) comprises fabricating a three-dimensional pattern at the tunneling junction by yellow light photoetching and dry etching with an etching depth not less than 0.5 nm.

12. The fabrication method of claim 9 , wherein the reflecting layer comprises a material with a work function of 4.0-5.0 eV and forming ohmic contact with the tunneling junction.

13. The fabrication method of claim 9 , further comprising:

fabricating a p-electrode and an n-electrode over the p-type semiconductor layer and the n-type semiconductor layer, respectively;

providing a supporting substrate having a patterned metal layer thereon, which bonds the supporting substrate with the p-electrode and the n-electrode; and

thinning the growth substrate to form a flip-chip light-emitting device.

14. The fabrication method of claim 9 , further comprising:

forming an electrode bonding layer over the reflecting layer;

providing a supporting substrate and bonding the supporting substrate with the electrode bonding layer; and

removing the growth substrate to expose the light-emitting epitaxial layer, over which fabricating an electrode, to thereby form a vertical light-emitting device.

15. A system comprising a plurality of UV semiconductor light-emitting devices, each device comprising:

a light-emitting epitaxial layer having one side as a light-emitting surface and another side as a non-light-emitting surface and comprising an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer;

a tunneling junction at the non-light-emitting side and comprising a patterned structure having openings to expose the light-emitting epitaxial layer;

an optical phase matching layer over a surface layer of the light-emitting epitaxial layer and transmissive of UV light; and

a reflecting layer covering the tunneling junction and the optical phase matching layer.

16. The system of claim 15 , wherein the reflecting layer comprises a material having a work function of about 4.0-5.0 eV, and forms ohmic contact with the tunneling junction.

17. The system of claim 16 , wherein the reflecting layer has a work function value of about 4.0-5.0 eV, and a reflectivity of not less than 70% for light with wavelengths less than 380 nm.

18. The system of claim 15 , wherein the tunneling junction has a patterned structure and a side with a solid slope with a gradient between 10°-85°.

19. The system of claim 18 , wherein the patterned structure comprises at least one of a band shape, an island shape, a round platform, a trapezoid platform, a cone shape, or a hemispheric shape.

20. The system of claim 15 , wherein the light-emitting epitaxial layer comprises a III-V group material that is a binary compound or ternary compound comprising at least one of Al, Ga, N, P, or In.