CN212161844U - Light-emitting diode - Google Patents

Abstract

The utility model belongs to the semiconductor field especially relates to a light emitting diode, including the substrate, set up in epitaxial layer on the substrate and with epitaxial layer electric connection's P electrode and N electrode, the epitaxial layer includes N type layer, luminescent layer and P type layer, the side of epitaxial layer has naked mesa, the mesa includes that the side is regional and bottom surface is regional, the side is regional to have a plurality of inclined planes, is located the below the slope on inclined plane is less than all the other the slope on inclined plane. The utility model discloses both avoid sacrificing too much upper light-emitting region, can effectively promote the lateral expansion ability of electron again, and then reduce emitting diode's forward voltage.

Description

Light-emitting diode

Technical Field

The utility model belongs to the semiconductor field especially relates to a light emitting diode.

Background

A Light Emitting Diode (LED) is a semiconductor Light Emitting element, which is manufactured by using a semiconductor PN junction injection type electroluminescence principle. The LED has the advantages of low energy consumption, small volume, long service life, good stability, fast response, stable light-emitting wavelength and other good photoelectric properties, and has good application in the fields of illumination, household appliances, display screens, indicator lamps and the like at present.

The market demands for low voltage and high brightness are increasing day by day, and how to further reduce the voltage of the light emitting diode is a problem that needs to be solved in order to meet the application demands of the light emitting diode in various fields.

Disclosure of Invention

For further reducing emitting diode's voltage, the utility model provides a emitting diode, including the substrate, set up in epitaxial layer on the substrate and with epitaxial layer electric connection's P electrode and N electrode, the epitaxial layer includes N type layer, luminescent layer and P type layer, the side of epitaxial layer has naked mesa, the mesa includes that the side is regional and bottom surface is regional, the side is regional to have a plurality of inclined planes, is located the below the slope of inclined plane is less than all the other the slope of inclined plane.

Preferably, the inclined surface includes a first inclined surface and a second inclined surface connected to the first inclined surface.

Preferably, the first inclined surface extends from an upper surface of the P-type layer to a lower surface of the light emitting layer, and the second inclined surface extends from the lower surface of the light emitting layer to the bottom surface region.

Preferably, the first inclined surface forms an angle a with the light emitting layer, the second inclined surface forms an angle B with a reverse extension line of the bottom surface region, and the angle a is greater than the angle B.

Preferably, the angle A is 30-90 degrees, and the angle B is 10-60 degrees.

Preferably, a boundary between the first inclined surface and the second inclined surface is lower than an upper surface of the N-type layer and higher than the bottom surface region.

Preferably, an electron blocking layer is further included between the P-type layer and the light emitting layer.

Preferably, the electron blocking layer is a P-type gallium nitride aluminum layer.

Preferably, a current spreading layer is arranged between the P-electrode and the P-type layer.

Preferably, a buffer layer is arranged between the substrate and the epitaxial layer.

The utility model discloses a make into a plurality of inclined planes with the side of epitaxial layer for the slope that is located the inclined plane of below is less than all the other inclined plane slopes, and this kind of structure had both avoided sacrificing too much upper light-emitting region, and it is mild to make the inclined plane of below again, and the lateral expansion area of increase N type layer reduces the impedance of lateral expansion, thereby effectively promotes the lateral expansion ability of electron, and then reduces emitting diode's forward voltage.

Drawings

Fig. 1 is a schematic cross-sectional view of a light emitting diode in the prior art.

Fig. 2 is a schematic cross-sectional view of another led in the prior art.

Fig. 3 is a schematic cross-sectional view of a light emitting diode according to the present invention.

The attached drawings are marked as follows: 10. A substrate; 20. a buffer layer; 30. an epitaxial layer; 31. an N-type layer; 32. a light emitting layer; 33. a P-type layer; 40. a table top; 41. a side region; 411. a first inclined surface; 412. a second inclined surface; 42. 50, an electron blocking layer; 60. a current spreading layer; 70. a P electrode; 80. and an N electrode.

Detailed Description

The structure of the light emitting diode of the present invention will be described in detail with reference to the schematic drawings, and before further describing the present invention, it is to be understood that the present invention is not limited to the specific embodiments described below, since modifications can be made to the specific embodiments. It is also to be understood that the embodiments are presented by way of illustration, not of limitation, since the scope of the invention is defined by the appended claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

When the Light Emitting Diode (LED) is energized, current is injected from the P-electrode 70, through the epitaxial layer 30 to the N-electrode 80. There is a large internal resistance during the current injection, which mainly includes the ohmic contact resistance between the conductive semiconductor layer and the electrode, the resistance of the current spreading layer 60, the lateral spreading resistance of the N-type layer 31, and the resistance of the P-type layer 33, and the magnitude of the resistance affects the voltage of the light emitting diode.

The utility model discloses a horizontal extension resistance to N type layer 31 improves. The lateral spreading resistance is a resistance that needs to be laterally spread back to the N-electrode 80 after the current is conducted to the N-type layer 31. Referring to fig. 1 and 2, each is one of the led structures commonly found in the prior art.

With continued reference to fig. 1 and 2, in fig. 1, the side surface of the epitaxial layer 30 is a vertical step-like structure, which can maximally preserve the area of the light-emitting region, but because the angle of the side surface of the epitaxial layer 30 is too vertical, although the area of the light-emitting region can be maximally preserved, the area M1 of the current laterally expanded at the N-type layer 31 is small, and the lateral expansion capability of the electrons is relatively weak; and the side of epitaxial layer 30 is the inclined plane that has single slope in fig. 2, this kind of structure has increased the area of horizontal extension compared with the structure of fig. 1, but if the resistance of horizontal extension is further reduced, under the unchangeable circumstances of distance (the distance between N electrode 80 and epitaxial layer 30 is less, produce electric leakage phenomenon easily) between guaranteeing N electrode 80 and epitaxial layer 30, then need reduce inclination, make the side angle more gentle, and then increase the area of horizontal extension M2, but when reducing inclination, can sacrifice the more light-emitting area in upper strata. Therefore, the utility model discloses aim at designing out the luminous zone area that neither influences the upper strata, reduced the emitting diode of horizontal spreading resistance again.

Referring to fig. 3, the present invention discloses a light emitting diode, including a substrate 10, an epitaxial layer 30 disposed on the substrate 10, and a P electrode 70 and an N electrode 80 electrically connected to the epitaxial layer 30, wherein the epitaxial layer 30 includes an N-type layer 31, a light emitting layer 32 and a P-type layer 33, a side of the epitaxial layer 30 has a bare mesa 40, the mesa 40 includes a side region 41 and a bottom region 42, the side region 41 has a plurality of inclined surfaces, and a slope of the inclined surface located at the bottom is smaller than slopes of the rest of the inclined surfaces.

In this embodiment, it is preferable that the number of the inclined surfaces is 2, the inclined surfaces are a first inclined surface 411 and a second inclined surface 412 connected to the first inclined surface 411, the slope of the first inclined surface 411 is greater than that of the second inclined surface 412, and the second inclined surface 412 is located below. Specifically, the first inclined surface 411 extends from the upper surface of the P-type layer 33 to the lower surface of the light emitting layer 32, and the second inclined surface 412 extends from the lower surface of the light emitting layer 32 to the bottom surface region 42. The first inclined surface 411 forms an angle a with the light emitting layer 32, and the second inclined surface 412 forms an angle B with the reverse extension line of the bottom surface region 42, the angle a being greater than the angle B. The angle A is 30-90 degrees, and the angle B is 10-60 degrees, so that the lateral expansion resistance is reduced, and the area sacrifice of the light emitting area is minimized.

Further, the boundary between the first inclined surface 411 and the second inclined surface 412 is not limited to the lower surface of the light emitting layer 32, and the boundary between the first inclined surface 411 and the second inclined surface 412 may be lower than the upper surface of the N-type layer 31 and higher than the bottom surface region 42.

The P-type layer 33 or the N-type layer 31 is an N-or P-doped layer, respectively, with an N-type dopant such as Si, Ge, or Sn. The p-type doped layer has a p-type dopant such as Mg, Zn, Ca, Sr, or Ba, without excluding other element equivalent substitution dopings. The P-type layer 33 or the N-type layer 31 may be gallium nitride-based, gallium arsenide-based, or gallium phosphide-based. The light-emitting layer 32 is made of a material capable of providing light radiation, the specific radiation band is 390-950 nm, such as blue, green, red, yellow, orange, infrared light, and the light-emitting layer 32 may be a single quantum well or a multiple quantum well. The buffer layer 20 is also arranged between the substrate 10 and the epitaxial layer 30, and the buffer layer 20 can reduce the lattice difference between the substrate 10 and the epitaxial layer, reduce the growth defects and improve the internal quantum efficiency of the semiconductor element.

A current spreading layer 60 is disposed between the P-electrode 70 and the P-type layer 33. The current spreading layer 60 is a conductive film, and the current spreading layer 60 can spread the current to the region other than the region below the P-electrode 70 as much as possible, thereby promoting the current spreading and improving the light emitting efficiency of the light emitting diode. The current spreading layer 60 may be one or a combination of several selected from an indium tin oxide layer, a zinc indium tin oxide layer, an indium zinc oxide layer, a zinc tin oxide layer, a gallium indium oxide layer, a gallium zinc oxide layer, an aluminum-doped zinc oxide layer, or a fluorine-doped tin oxide layer. The present embodiment is preferably an ito layer, which has good conductivity and transmittance, and can effectively reduce voltage and improve light extraction.

An electron blocking layer 50 is further disposed between the P-type layer 33 and the light-emitting layer 32, and the electron blocking layer 50 blocks electrons from leaking to the P-type layer 33, so that electrons are confined in the light-emitting layer 32, the probability of non-radiative recombination due to electron leakage is reduced, and the internal quantum efficiency of the semiconductor device is increased. The electron blocking layer 50 of this embodiment is preferably a P-type gallium nitride aluminum layer.

The utility model discloses a make into a plurality of inclined planes with epitaxial layer 30's side for the slope that is located the inclined plane of below is less than the slope of all the other inclined planes, and this kind of structure had both avoided sacrificing too much upper light-emitting region, and it is mild to make the inclined plane of below again, and the lateral expansion area of increase N type layer 31 reduces the impedance of lateral expansion, thereby effectively promotes the lateral expansion ability of electron, and then reduces emitting diode's forward voltage.

It should be understood that the above-mentioned embodiments are the preferred embodiments of the present invention, and the scope of the present invention is not limited to these embodiments, and any changes made according to the present invention are all included in the protection scope of the present invention.

Claims (10)

1. A light emitting diode comprises a substrate, an epitaxial layer arranged on the substrate, and a P electrode and an N electrode which are electrically connected with the epitaxial layer, wherein the epitaxial layer comprises an N-type layer, a light emitting layer and a P-type layer, and the light emitting diode is characterized in that: the side surface of the epitaxial layer is provided with an exposed mesa which comprises a side surface area and a bottom surface area, the side surface area is provided with a plurality of inclined surfaces, and the slope of the inclined surface positioned at the lowest part is smaller than that of the rest inclined surfaces.

2. A light emitting diode according to claim 1 wherein: the inclined surfaces include a first inclined surface and a second inclined surface connected to the first inclined surface.

3. A light emitting diode according to claim 2, wherein: the first inclined surface extends from an upper surface of the P-type layer to a lower surface of the light emitting layer, and the second inclined surface extends from the lower surface of the light emitting layer to the bottom surface region.

4. A light emitting diode according to claim 2, wherein: the first inclined plane and the light-emitting layer form an angle A, the second inclined plane and a reverse extension line of the bottom surface area form an angle B, and the angle A is larger than the angle B.

5. The light-emitting diode according to claim 4, wherein: the angle A is 30-90 degrees, and the angle B is 10-60 degrees.

6. A light emitting diode according to claim 2, wherein: the junction of the first inclined plane and the second inclined plane is lower than the upper surface of the N-type layer and higher than the bottom surface area.

7. A light emitting diode according to claim 1 wherein: an electron blocking layer is arranged between the P-type layer and the light-emitting layer.

8. The led of claim 7, wherein: the electron blocking layer is a P-type gallium nitride aluminum layer.

9. A light emitting diode according to claim 1 wherein: and a current expansion layer is arranged between the P electrode and the P type layer.

10. A light emitting diode according to claim 1 wherein: and a buffer layer is arranged between the substrate and the epitaxial layer.

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