WO2019071586A1

WO2019071586A1 - Deep ultraviolet led light-emitting structure and light-emitting device

Info

Publication number: WO2019071586A1
Application number: PCT/CN2017/106120
Authority: WO
Inventors: 何宗江; 贾志强
Original assignee: 深圳前海小有技术有限公司; 深圳佑荟半导体有限公司
Priority date: 2017-10-13
Filing date: 2017-10-13
Publication date: 2019-04-18

Abstract

A deep ultraviolet LED light-emitting structure and a deep ultraviolet LED light-emitting device. The light-emitting device comprises a first electrode, a second electrode, and a light-emitting structure having a reflecting layer. The deep ultraviolet LED light-emitting structure and the deep ultraviolet LED light-emitting device improve the structure of the reflecting layer, thereby improving optical power.

Description

Deep ultraviolet LED light emitting structure and light emitting device

Technical field

The present invention relates to the field of semiconductor technology, and in particular, to a deep ultraviolet LED light emitting structure and a deep ultraviolet LED light emitting device.

Background technique

The deep ultraviolet LED refers to an LED having an emission wavelength of 280 nm or less. Currently, such an LED is mostly made of a semiconductor material of AlGaN. However, the crystal quality of AlGaN is poor, and good doping and ohmic contact cannot be achieved, resulting in low efficiency of deep ultraviolet LED illumination of AlGaN materials.

The light emitted from the P-type AlGaN side of the ultraviolet LED light-emitting device of the prior art does not form an effective output, resulting in low optical power.

In view of the above, in order to overcome the defects in the prior art, it is a technical problem to be solved in the art to provide a new deep ultraviolet LED light emitting structure and a new deep ultraviolet LED light emitting device.

Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a deep ultraviolet LED light emitting structure and a deep ultraviolet LED light emitting device having the above light emitting structure, in view of the above drawbacks of the prior art.

The object of the present invention can be achieved by the following technical measures:

The present invention provides a deep ultraviolet LED light emitting structure comprising a first semiconductor layer, a reflective layer including at least one reflective unit, an active layer and a second semiconductor layer, which are sequentially stacked; the reflective unit includes a plurality of a first refractive layer and a plurality of second refractive layers, wherein the first refractive layer and the second refractive layer are alternately stacked, and the refractive index of the first refractive layer is greater than the refractive index of the second refractive layer.

Preferably, the reflective layer comprises a plurality of spaced apart reflective columns, each reflective column comprising a reflective unit or a plurality of reflective units arranged in a stack.

Preferably, the upper surface of the first refractive layer is a flat surface, and the lower surface is a concave curved surface, and the upper surface of the second refractive layer is a convex curved surface matching the concave curved surface, and the lower surface is a flat surface.

Preferably, the second refractive layer has an arcuate cross section, and the intermediate thicknesses of the first refractive layer and the second refractive layer are respectively a first thickness and a second thickness, and the first thickness is (center wavelength + 2) × The refractive index of a refractive layer is 4.15, and the second thickness is (center wavelength + 2) × refractive index of the second refractive layer / 4.15.

Preferably, the first refractive layer and the second refractive layer are each provided with a plurality of spaced protrusions, and the protrusions in the adjacent two refractive layers are staggered.

Preferably, the reflective layer or the reflective pillar comprises a first reflective unit and a second reflective unit that are vertically staggered, the refractive index of the first reflective unit being greater than the refractive index of the second reflective unit; the first reflection The unit includes a plurality of first sub-refractive layers and a plurality of second sub-refractive layers, wherein the first sub-refractive layer and the second sub-refractive layer are alternately stacked; the second reflective unit includes a plurality of third sub-refractive layers and a fourth sub-refracting layer, wherein the third sub-refracting layer and the fourth sub-refracting layer are alternately stacked.

Preferably, a difference between a refractive index of the first reflective unit and a refractive index of the second reflective unit is 0.15 to 0.35; the first sub-refractive layer, the second sub-refracting layer, the third sub-refracting layer, and fourth sub-refractive layer by Al _{_X} Ga _{_1-X} N materials, different sub-refractive layer Al _{_X} Ga _{_1-X} N X values of different materials, where, 0 <X <1.

Preferably, a difference between a refractive index of the first reflective unit and a refractive index of the second reflective unit is 0.15 to 0.35; and the first sub-refractive layer and the third sub-refractive layer respectively have different Al values _{The X} Ga _1-X N material is made of 0<X<1, and the second sub-refractive layer and the fourth sub-refractive layer are made of an AIN material.

Preferably, the light emitting structure further includes a substrate, a third semiconductor layer disposed between the reflective layer and the active layer, and a buffer layer disposed between the substrate and the second semiconductor layer, The first semiconductor layer is a P-type GaN layer, the second semiconductor layer is an N-type AlGaN layer, the third semiconductor layer is a P-type AlGaN layer, the buffer layer is an AIN layer, and the active layer is grown An active layer of an AlGaN superlattice structure.

The invention also provides a deep ultraviolet LED light emitting device, comprising:

The above deep ultraviolet LED light emitting structure;

a first electrode disposed on the first semiconductor layer of the light emitting structure; and

a second electrode disposed on the second semiconductor layer of the light emitting structure.

Preferably, the light emitting device further includes a substrate connected to both the first electrode and the second electrode, and the first surface of the substrate is provided with an insulating layer.

Preferably, the first region of the first surface of the substrate is formed with a first conductive layer, the second region of the first surface of the substrate is formed with a second conductive layer, and the first electrode and the second electrode respectively pass through the first region A conductive layer and a second conductive layer are connected to the substrate.

The deep ultraviolet LED light emitting structure and the light emitting device of the invention improve the structure of the reflective layer, form a more effective output, and improve the optical power.

DRAWINGS

1 is a schematic structural view of a deep ultraviolet LED light emitting structure according to a first embodiment of the present invention.

2 is a schematic structural view of a deep ultraviolet LED light emitting structure according to a second embodiment of the present invention.

3 is a schematic view showing the structure of a reflective layer of a first preferred embodiment of the light-emitting structure of the present invention.

4 is a schematic view showing the structure of a reflective layer of a second preferred embodiment of the light-emitting structure of the present invention.

Figure 5 is a schematic view showing the structure of a reflective layer of a third preferred embodiment of the light-emitting structure of the present invention.

6 is a schematic structural view of a preferred embodiment of a reflective layer in a deep ultraviolet LED light emitting structure according to a second embodiment of the present invention.

Fig. 7 is a schematic structural view of a deep ultraviolet LED light emitting device according to a first embodiment of the present invention.

Fig. 8 is a schematic structural view of a deep ultraviolet LED light emitting device according to a second embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The description of the embodiments of the present invention is intended to be illustrative and not restrictive The features of various specific embodiments, as well as the method steps and sequences thereof, are constructed and manipulated in the embodiments. However, other specific embodiments may be utilized to achieve the same or equivalent functions and sequence of steps.

The embodiment of the present invention provides a deep ultraviolet LED light emitting structure 100. Referring to FIG. 1 , the light emitting structure 100 includes a first semiconductor layer 31, a reflective layer 32, an active layer 33, and a first layer stacked in this order from bottom to top. A second semiconductor layer 34, wherein the reflective layer 32 comprises at least one reflective unit.

Further, the light emitting structure further includes a substrate 37, a third semiconductor layer 35 disposed between the active layer 33 and the reflective layer 32, and a buffer layer 36 disposed between the substrate 37 and the second semiconductor layer 34. Further, the first semiconductor layer 31 is a P-type GaN layer, the second semiconductor layer 34 is an N-type AlGaN layer, the third semiconductor layer 35 is a P-type AlGaN layer, and the buffer layer 36 is an AIN layer. The second semiconductor layer 34 and the buffer layer 36 have the same area, the third semiconductor layer 35 and the active layer 33 have the same area, and the active layer 33 is an active layer in which an AlGaN superlattice structure is grown.

In the preferred embodiment shown in FIG. 1, the reflective layer 32 is continuously disposed between the first semiconductor 31 and the active layer 33.

In the preferred embodiment shown in FIG. 2, the reflective layer 32 is discontinuously disposed between the first semiconductor 31 and the active layer 33, forming a plurality of cutouts, and the reflective layer 32 includes a plurality of spaced apart reflective pillars 32'. Each of the reflective pillars 32' includes a reflective unit or a plurality of reflective units arranged in a stack.

In the first preferred embodiment shown in FIG. 3, the reflective layer 32 is composed of a reflective unit 32a including a plurality of first refractive layers 301 and a plurality of second refractive layers 302, first refractive layers 301 and The two refractive layers 302 are alternately stacked, and the refractive index of the first refractive layer 301 is greater than the refractive index of the second refractive layer 302. In order to facilitate the reflection of light, the lower surface of the first refractive layer 301 is a concave curved surface, and the upper surface of the second refractive layer 302 is a convex curved surface that cooperates with the concave curved surface. Further, the second refractive layer 302 has an arcuate cross section, and the intermediate thicknesses of the first refractive layer 301 and the second refractive layer 302 are a first thickness h1 and a second thickness h2, respectively. The first thickness h1 is the thickness of the thinnest portion of the first refractive layer 301, extending from the upper surface of the first refractive layer 301 to the curved vertex of the lower surface; the second thickness h2 is the thickness of the thickest portion of the second refractive layer 302, from the first The curved vertex of the upper surface of the second refractive layer 302 extends to the lower surface. The first refractive layer 301 and the second refraction layer 302 are made of Al _X Ga _1-X N material, the first refractive layer 301 and the material _1-X N X Al _X Ga value 302 different from the second refractive layer, wherein , 0 < X < 1. In the present embodiment, the thickness of the reflecting unit 32a is 1 μm or less, and the total number of layers of the two refractive layers is 2 to 18 layers. The first thickness h1 is (center wavelength + 2) × the refractive index of the first refractive layer / 4.15, the second thickness h2 is (center wavelength + 2) × the refractive index of the second refractive layer / 4.15, which can achieve 99.9% near the center wavelength. The reflection greatly improves the light-emitting efficiency of the bottom surface and improves the emission efficiency of the deep ultraviolet light.

Each of the reflecting columns 32' may also adopt the structure shown in Fig. 3, and each of the reflecting columns 32' is a reflecting unit 32a.

In the second preferred embodiment shown in FIG. 4, the reflective layer 32 is composed of a reflective unit 32b including a plurality of first refractive layers 301' and a plurality of second refractive layers 302', the first refractive layer 301 The 'and the second refractive layer 302' are alternately stacked, and the first refractive layer 301' and the second refractive layer 302' are internally provided with a plurality of spaced-apart protrusions 303. The protrusions 303 in the adjacent two refractive layers are staggered, and the refractive index of the first refractive layer 301' is larger than the refractive index of the second refractive layer 302'. The protrusions 303 are preferably hemispherical, and the protrusions 303 are preferably made of an aluminum nitride (AlN) material, which achieves both electrical conductivity and reflection, and the reflectance of such a structure can reach 92%.

Each of the reflecting columns 32' may also adopt the structure shown in Fig. 4, and each of the reflecting columns 32' is a reflecting unit 32b.

In the third preferred embodiment shown in FIG. 5, the reflective layer 32 is composed of a plurality of vertically stacked reflective units, and the reflective layer 32 includes a first reflective unit 32c and a second reflective unit 32d which are vertically staggered and stacked, the first reflection The refractive index of the unit 32c is greater than the refractive index of the second reflective unit 32d; the first reflective unit 32c includes a plurality of first sub-refractive layers 401 and a plurality of second sub-refracting layers 402, wherein the first sub-refracting layer 401 and the second The sub-refracting layers 402 are alternately stacked; the second reflecting unit 32d includes a plurality of third sub-refracting layers 403 and a plurality of fourth sub-refracting layers 404, wherein the third sub-refracting layer 403 and the fourth sub-refracting layer 404 are alternately stacked. Further, a difference between a refractive index of the first reflective unit 32c and a refractive index of the second reflective unit 32d is 0.15 to 0.35; the first sub-refractive layer 401, the second sub-refracting layer 402, and the third sub-refracting layer 403 and fourth sub-refractive layer 404 are made of Al _{_X} Ga _{_1-X} N material, Al _{_X} Ga _{_1-X} N different sub-refractive material layers different value X, where, 0 <X <1. In this embodiment, each of the first reflective unit 32c and the second reflective unit 32d is a superlattice structure layer, and the reflectance can reach 99.96%.

Each of the reflecting columns 32' may also adopt the structure shown in Fig. 5. Referring to Fig. 6, each of the reflecting columns 32' includes a first reflecting unit 32c and a second reflecting unit 32d which are vertically staggered and stacked.

The embodiment of the present invention further provides a deep ultraviolet LED light emitting device 200. Referring to FIG. 7 and FIG. 8 , the light emitting device 200 includes a substrate 10 , a first electrode 201 , a second electrode 202 , and a light emitting structure 100 . Please refer to the above for the structure, and I will not repeat them here. The first electrode 201 is disposed on the first semiconductor layer 31, and the second electrode 202 is disposed on the second semiconductor layer 34.

The first surface of the substrate 10 is provided with an insulating layer 101, the first region of the first surface of the substrate 10 is formed with a first conductive layer 38a, and the second region of the first surface of the substrate 10 is formed with a second conductive layer 38b. The first electrode 201 and the second electrode 202 are connected to the substrate 10 through the first conductive layer 38a and the second conductive layer 38b, respectively. The other side of the first electrode 201 is connected to the first semiconductor layer 31, and the other end of the second electrode 202 is connected to the second semiconductor layer 34 via the isolation layer 36. The first electrode 201 is a positive electrode and the second electrode 202 is a negative electrode.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A deep ultraviolet LED light emitting structure, comprising: a first semiconductor layer, a reflective layer including at least one reflective unit, an active layer and a second semiconductor layer, which are sequentially stacked; the reflective unit includes a plurality of a first refractive layer and a plurality of second refractive layers, wherein the first refractive layer and the second refractive layer are alternately stacked, and the refractive index of the first refractive layer is greater than the refractive index of the second refractive layer.
The deep ultraviolet LED light emitting structure according to claim 1, wherein the reflective layer comprises a plurality of spaced apart reflective columns, each of the reflective columns comprising a reflective unit or a plurality of reflective units arranged in a stack.
The deep ultraviolet LED light emitting structure according to claim 1 or 2, wherein the upper surface of the first refractive layer is a flat surface and the lower surface is a concave curved surface, and the upper surface of the second refractive layer is The convex curved surface and the lower surface of the concave curved surface are plane.
The deep ultraviolet LED light emitting structure according to claim 3, wherein the second refractive layer has an arcuate cross section, and the intermediate thicknesses of the first refractive layer and the second refractive layer are respectively a first thickness and a second The thickness, the first thickness is (center wavelength + 2) × the refractive index of the first refractive layer / 4.15, the second thickness is (center wavelength + 2) × the refractive index of the second refractive layer / 4.15.
The deep ultraviolet LED light emitting structure according to claim 1 or 2, wherein each of the first refractive layer and the second refractive layer is provided with a plurality of spaced protrusions, and two adjacent refractive layers. The bumps in the middle are staggered.
The deep ultraviolet LED light emitting structure according to claim 1 or 2, wherein the reflective layer or the reflective pillar comprises a first reflective unit and a second reflective unit which are vertically staggered and stacked, and a refractive index of the first reflective unit The first reflective unit includes a plurality of first sub-refractive layers and a plurality of second sub-refractive layers, wherein the first sub-refractive layer and the second sub-refractive layer are alternately stacked; The second reflective unit includes a plurality of third sub-refractive layers and a plurality of fourth sub-refractive layers, wherein the third sub-refractive layer and the fourth sub-refractive layer are alternately stacked.
The deep ultraviolet LED light emitting structure according to claim 6, wherein a difference between a refractive index of the first reflecting unit and a refractive index of the second reflecting unit is 0.15 to 0.35; the first sub-refraction layer, the second sub-refractive layer, the third layer and the fourth sub-sub-refractive index layers are made of Al X Ga 1-X N materials, different Al X Ga 1-X N different sub-refractive material layers value of X, Where 0<X<1.
The deep ultraviolet LED light emitting structure according to claim 6, wherein a difference between a refractive index of the first reflecting unit and a refractive index of the second reflecting unit is 0.15 to 0.35; the first sub-refraction The layer and the third sub-refractive layer are respectively made of Al X Ga 1-X N materials having different X values, wherein 0<X<1, and the second sub-refractive layer and the fourth sub-refractive layer are made of AIN material .
The deep ultraviolet LED light emitting structure according to claim 1 or 2, wherein the light emitting structure further comprises a substrate, a third semiconductor layer disposed between the reflective layer and the active layer, and the lining Between the bottom and the second semiconductor layer a buffer layer, the first semiconductor layer is a P-type GaN layer, the second semiconductor layer is an N-type AlGaN layer, the third semiconductor layer is a P-type AlGaN layer, and the buffer layer is an AIN layer, The active layer is an active layer grown with an AlGaN superlattice structure.
A deep ultraviolet LED light emitting device, characterized in that the light emitting device comprises:

The deep ultraviolet LED light emitting structure according to any one of claims 1 to 9;

a first electrode disposed on the first semiconductor layer of the light emitting structure; and

a second electrode disposed on the second semiconductor layer of the light emitting structure.
The deep ultraviolet LED lighting device according to claim 10, wherein the light emitting device further comprises a substrate connected to both the first electrode and the second electrode, and the first surface of the substrate is provided with an insulating layer.
The deep ultraviolet LED light emitting device according to claim 11, wherein a first region of the first surface of the substrate is formed with a first conductive layer, and a second region of the first surface of the substrate is formed with a second conductive layer The first electrode and the second electrode are connected to the substrate through a first conductive layer and a second conductive layer, respectively.