TWI459583B - Light-emitting device - Google Patents

Description

Light-emitting element

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a light-emitting element, and more particularly to a light-emitting element that enhances light extraction efficiency by an annular photonic crystal structure and controls the collimating characteristics of the light-emitting field shape.

The light extraction efficiency of a solid-state semiconductor light-emitting device (such as a light-emitting diode) is limited by the total reflection between the semiconductor material and an external material (generally air or epoxy) interface, so that the light-emitting element overflows the light amount of the component. It only accounts for a few percentages of the amount of internal luminescence.

1 and 2 illustrate a conventional light emitting diode 100 disclosed in U.S. Patent 7,098,589. The LED 100 includes a substrate 120 and a multilayer stack 122 disposed on the substrate 120. The multilayer stack 122 includes a gallium nitride layer 134 having a plurality of circular holes 150. In particular, US 7,098,589 utilizes the circular aperture 150 to disrupt the total reflection of the interface to enhance light extraction efficiency. In general, the larger the hole has better light extraction efficiency, however, the large hole affects the current distribution of the light-emitting element and the light-emitting efficiency of the light-emitting layer, resulting in a decrease in overall light-emitting efficiency.

The present invention provides a light-emitting element that utilizes an annular photonic crystal structure that destroys total reflection of the interface to enhance light extraction efficiency while simultaneously controlling the collimation characteristics of the light-emitting field shape.

In order to achieve the above object, the present invention provides a light-emitting element comprising a substrate, at least one light-emitting structure disposed on the substrate and capable of generating a light, and an annular photonic crystal structure disposed in the light-emitting structure, wherein the ring The photonic crystal structure includes a plurality of annular holes.

The light-emitting element of the present invention has a better light-emitting amount because it has the annular photonic crystal structure as compared with the conventional light-emitting element having no photonic crystal. Further, the light-emitting element of the present invention has better collimating characteristics due to the light-emitting diode structure having a circular hole as compared with the conventional light-emitting diode having a circular hole.

3 and 4 illustrate the light-emitting element 10 of the present invention. The light emitting device 10 includes a substrate 12, at least one light emitting structure 20 disposed on the substrate 12 and capable of generating a light 36, an N-type contact electrode 22, a P-type contact electrode 24, and a light-emitting structure 20 disposed in the light-emitting structure 20. The annular photonic crystal structure 30. The annular photonic crystal structure 30 includes a plurality of pillars 32 disposed in the light emitting structure 20 and a plurality of annular holes 34 surrounding the plurality of pillars 32. The light emitting structure 20 can be a light emitting diode or a laser diode including at least one N-type semiconductor layer 14, a light emitting layer 16, and a P-type semiconductor layer 18.

The light-emitting structure 20 has a light-emitting side 26 disposed on the light-emitting side 26 of the light-emitting structure 20 . The plurality of annular holes 34 may have a depth less than or equal to the thickness of the P-type semiconductor layer 18.

The plurality of annular holes 34 are between D and 0.2 λ, wherein λ is the wavelength of the light 36. The inner ring 34A and the outer ring 34B of the annular hole 34 may be circular, and the ratio of the outer ring radius (R) of the annular hole 34 to the distance D between the annular holes 34 is preferably between 0.1 and 0.5. In addition, the inner ring 34A and the outer ring 34B of the annular hole 34 can also be selectively designed as an ellipse, a triangle, a rectangle or a polygon.

Fig. 5 is a view showing a change in light extraction efficiency of the light-emitting element 10 of the present invention. The horizontal axis represents the ratio of the radius (r) of the inner ring 34A of the annular hole 34 to the radius (R) of the outer ring 34B, and the vertical axis represents the amount of light emitted from the light-emitting element 10 of the present invention and the amount of light emitted from a light-emitting element having no photonic crystal. The ratio of the ratio (R/D) of the radius (R) to the spacing D of the outer ring 34B of the annular hole 34 is set to 0.45. Compared with the conventional light-emitting element having no photonic crystal, the light-emitting element 10 of the present invention obviously has a large amount of light emitted, that is, the light-emitting element 10 of the present invention has a comparative use of the annular photonic crystal structure 20, thereby A large amount of light.

Fig. 6 illustrates the far field pattern of the light-emitting element 10 of the present invention and the far-field pattern of the conventional light-emitting diode 100. The amount of light emitted by the light-emitting element 10 of the present invention at around 0 degrees is remarkably superior to that of the conventional light-emitting diode 100 at around 0 degrees, that is, the light-emitting element 10 of the present invention has the annular photonic crystal structure 20, Has better collimation characteristics. In other words, the annular photonic crystal structure 20 can serve as a light collimating structure to enhance the collimating characteristics of the light emitting element 10.

7 to 10 illustrate the lattice arrangement of the photonic crystal 30 of the present invention, which may have a quadruple symmetry (90 degree rotational symmetry), a sixfold symmetry (60 degree rotational symmetry) or multiple symmetry. In addition, the crystal lattice of the photonic crystal 30 may also be periodically arranged (as shown in FIGS. 7 to 9), quasi-periodic (as shown in FIG. 4), and non-periodic (ie, randomly arranged).

The technical and technical features of the present invention have been disclosed as above, and those skilled in the art can still make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be construed as being limited by the scope of the appended claims

10. . . Light-emitting element

12. . . Substrate

14. . . N-type semiconductor layer

16. . . Luminous layer

18. . . P-type semiconductor layer

20. . . Light structure

twenty two. . . N-type contact electrode

twenty four. . . P-type contact electrode

26. . . Light exit side

30. . . Ring photonic crystal structure

32. . . Cylinder

34. . . Circular hole

34A. . . Inner ring

34B. . . Outer ring

36. . . Light

100. . . Light-emitting diode

120. . . Substrate

122. . . Multi-layer stacking

134. . . Gallium nitride layer

150. . . Round hole

1 and 2 illustrate a conventional light-emitting diode; FIGS. 3 and 4 illustrate a light-emitting element of the present invention; FIG. 5 illustrates a light-receiving efficiency change of the light-emitting element of the present invention; and FIG. 6 illustrates a light-emitting element of the present invention. The far field field shape and the far field field shape of the conventional light emitting diode; and FIGS. 7 to 10 illustrate the lattice arrangement of the photonic crystal of the present invention.

10. . . Light-emitting element

12. . . Substrate

14. . . N-type semiconductor layer

16. . . Luminous layer

18. . . P-type semiconductor layer

20. . . Light structure

twenty two. . . N-type contact electrode

twenty four. . . P-type contact electrode

26. . . Light exit side

30. . . Ring photonic crystal structure

32. . . Cylinder

34. . . Circular hole

36. . . Light

Claims (20)

A light-emitting element comprising: a substrate; at least one light-emitting structure disposed on the substrate, wherein the light-emitting structure comprises a P-type semiconductor layer; and an annular photonic crystal structure disposed in the light-emitting structure, the ring-shaped photonic crystal The structure includes a plurality of annular holes having a depth less than or equal to a thickness of the P-type semiconductor layer. A light-emitting element according to claim 1, wherein the light-emitting structure is a light-emitting diode or a laser diode. The illuminating element of claim 1, wherein the plurality of annular holes are between 0.2λ and 10λ, and λ is the wavelength of the light. The illuminating element of claim 1, wherein the plurality of annular holes are symmetrically arranged periodically, quasi-periodically or non-periodically. The light-emitting element of claim 1, wherein the plurality of annular holes are quadruple symmetric, six-fold symmetric or multiple symmetric. The illuminating element of claim 1, wherein the inner and outer rings of the annular hole are circular, elliptical, triangular, rectangular or polygonal. The light-emitting element of claim 1, wherein the light-emitting structure has a light-emitting side, and the ring-shaped photonic crystal structure is disposed on a light-emitting side of the light-emitting structure. A light-emitting element according to claim 1, wherein the annular photonic crystal structure comprises: a cylinder; and an annular hole surrounding the cylinder. The illuminating element of claim 8, wherein the cylinder and the annular hole are round The ratio of the radius of the outer ring of the annular hole to the distance between the annular holes is between 0.1 and 0.5. The light-emitting element of claim 8, wherein the cylinder and the annular hole are circular, and a ratio of a radius of the outer ring of the annular hole to an inner ring radius of the annular hole is greater than 0 but less than 1. A light-emitting element comprising: a substrate; at least one light-emitting structure disposed on the substrate; and a light collimating structure disposed in the light-emitting structure, comprising a plurality of columns and a plurality of surrounding the plurality of columns Ring hole. The illuminating element of claim 11, wherein the illuminating structure is a light emitting diode or a laser diode. The illuminating element of claim 11, wherein the plurality of annular holes are between 0.2λ and 10λ, and λ is the wavelength of the light. The illuminating element according to claim 11, wherein the plurality of annular holes are periodically arranged, quasi-periodically arranged or non-periodically arranged. The illuminating element of claim 11, wherein the plurality of annular holes are quadruple symmetric, sixfold symmetric or multiple symmetrical. The illuminating element of claim 11, wherein the illuminating structure comprises a P-type semiconductor layer, and the plurality of annular holes have a depth less than or equal to a thickness of the P-type semiconductor layer. The illuminating element of claim 11, wherein the inner and outer rings of the annular hole are circular, elliptical, triangular, rectangular or polygonal. The light-emitting element of claim 11, wherein the cylinder and the annular hole are circular, and a ratio of a radius of the outer ring of the annular hole to a distance between the annular holes is Between 0.1 and 0.5. The light-emitting element of claim 11, wherein the light-emitting structure has a light-emitting side, and the light-collecting structure is disposed on a light-emitting side of the light-emitting structure. According to the light-emitting element of claim 11, wherein the cylinder and the annular hole are circular, the ratio of the outer ring radius of the annular hole to the inner ring radius of the annular hole is greater than 0 but less than 1