TWI646702B - Light-emitting element - Google Patents

Abstract

A light-emitting element includes: a light-emitting stack having a side wall and an upper surface, and the light-emitting stack further includes an active layer capable of emitting a light; a first electrode on the light-emitting stack, including an interior and an exterior, And a plurality of extensions are electrically connected to the inside and the outside; and a light absorbing layer has a first portion surrounding the side wall of the light emitting stack; wherein the upper surface includes a first region and a second region, and the first region surrounds the second region.

Description

Light emitting element

The present invention relates to a light emitting element, and more particularly, to a light emitting element having a light emitting region and an electrode region substantially surrounding the light emitting region.

Light Emitting Diode (LED) is a solid-state lighting element, which has the advantages of low power consumption, low thermal energy generation, long working life, shock resistance, small size, fast response speed and good photoelectric characteristics, such as Stable emission wavelength. Therefore, light-emitting diodes are widely used in household appliances, equipment indicators, and optoelectronic products.

Light-emitting diodes generally include a light-emitting stack and two electrodes, and a current is applied to the light-emitting stack through the two electrodes to make it emit light. In general, the electrode can be designed to diffuse the current through the light-emitting stack, so that the light-emitting area and the surface area of the light-emitting stack are approximately the same. However, in other application fields, a high current density current needs to be injected into a limited light emitting area to improve the light emitting efficiency.

The invention provides a light-emitting element, comprising: a light-emitting stack having a side wall and an upper surface; the light-emitting stack further comprises an active layer capable of emitting a light; a first electrode on the light-emitting stack including a The interior and exterior, and a plurality of extensions are electrically connected to the interior and exterior; and a light absorbing layer has a first portion surrounding the side wall of the light emitting stack; wherein the upper surface includes a first region and a second region, and the first region Around the second zone.

To make the above features and advantages of the present invention more comprehensible, embodiments are described below in detail with reference to the accompanying drawings.

In order to make the description of the present invention more detailed and complete, please refer to the description of the following embodiments and cooperate with related drawings. However, the examples shown below are for exemplifying the light-emitting element of the present invention, and the present invention is not limited to the following examples. In addition, the dimensions, materials, shapes, relative arrangement, etc. of the component parts described in the examples in the present specification are not limited, and the scope of the present invention is not limited thereto, but merely a simple description. In addition, the size or positional relationship of the components shown in each illustration may be exaggerated for clarity. Furthermore, in the following description, in order to appropriately omit detailed descriptions, components of the same or the same nature are displayed with the same name and symbol.

1 and 2 are a light emitting device 100 according to a first embodiment of the present invention. FIG. 1 is a top view of the light emitting element 100. FIG. 2 is a cross-sectional view of the light-emitting element 100 along AA ′. The light-emitting element 100 includes a substrate 10, a light-emitting stack 13 on the substrate 10, a reflective layer 12 between the substrate 10 and the light-emitting stack 13, and a bonding layer 11 between the reflective layer 12 and the substrate 10. The light-emitting stack 13 includes a first-type semiconductor layer 131, a second-type semiconductor layer 133, and an active layer 132 located between the first-type semiconductor layer 131 and the second-type semiconductor layer 133. The first type semiconductor layer 131 and the second type semiconductor layer 133 provide electrons and holes, and the electrons and holes are recombined in the active layer 132 under a current drive to emit a light. The material of the light-emitting stack 13 includes group III-V semiconductor materials, such as Al _x In _y Ga _(1-xy) N or Al _x In _y Ga _(1-xy) P, where 0 ≦ x, y ≦ 1; (x + y) ≦ 1. Depending on the material of the active layer 132, the light emitting stack 13 can emit red light with a wavelength between 610 nm and 650 nm, green light with a wavelength between 530 nm and 570 nm, or a wavelength between 450 nm and 490. Blue light between nm. The method for forming the light-emitting stack 13 is not particularly limited. In addition to the organic metal chemical vapor deposition (MOCVD) method, molecular beam epitaxy (MBE), hydride vapor deposition (HVPE), vapor deposition, and ion plating can be used. method. The light-emitting element 100 further includes a first electrode 16 on the second-type semiconductor layer 133, a second electrode 17 on the substrate 10, a light-absorbing layer 18 on part of the first electrode 16, and an insulating layer 19 on the light-absorbing layer. 18 and the second type semiconductor layer 133. In this embodiment, the first electrode 16 is a patterned electrode and includes an inner portion 161, an outer portion 162, and a plurality of extension portions 163 to electrically connect the inner portion 161 and the outer portion 162. As shown in FIG. 2, the light emitting element 100 further includes an ohmic contact layer 15 between the inner portion 161 and the light emitting stack 13, and forms an ohmic contact with the inner portion 161 and the light emitting stack 13, respectively. The shape of the ohmic contact layer 15 is substantially the same as the shape of the inner portion 161. The ohmic contact layer 15 is not formed between the outer portion 162 and the light emitting stack 13. In another embodiment (not shown), the ohmic contact layer 15 is formed between the outer portion 162 and the light-emitting stack 13. The shape of the ohmic contact layer 15 is substantially the same as that of the outer portion 162. The shapes of the inner portion 161 and the outer portion 162 include a circle, a square, a quadrangle or a polygon. When the shapes of the inner portion 161 and the outer portion 162 are circular, the inner portion 161 and the outer portion 162 are concentric circles.

As shown in FIG. 2, the second-type semiconductor layer 133 of the light-emitting stack 13 has a sidewall 1331 and an upper surface. The upper surface has a first region 1332 and a second region 1333. The second region 1333 is defined by an outer portion 162 formed on the first region 1332 such that the first region 1332 surrounds the second region 1333. Specifically, the outer portion 162 on the first region 1332 surrounds the second region 1333. The inner portion 161 is located on a portion of the second region 1333, and the inner portion 161 does not completely cover the second region 1333 and exposes a portion of the second type semiconductor layer 133, so that the light from the active layer 132 emits light through the exposed portion Element 100 outside. The surface of the second region 1333 which is not covered by the inner portion 161 may be roughened by etching, such as dry etching or wet etching, to improve light extraction efficiency. The light absorbing layer 18 includes a first portion 181 surrounding the side wall 1331 and a second portion 182 on the first region 1332 on the upper surface of the light emitting stack 13. Specifically, the insulating layer 19 and the outer portion 162 are formed and covered on the first region 1332 on the upper surface of the second type semiconductor layer 133, and the second portion 182 of the light absorbing layer 18 is formed and covered on the insulating layer 19 and the outer portion 162. In addition, the insulating layer 19 covers the sidewall 1331 of the light-emitting stack 13, and the first portion 181 covers the sidewall of the insulating layer 19. As shown in FIG. 2, since the ohmic contact layer 15 is formed only between the inner portion 161 and the light-emitting stack 13, the light from the active layer 132 (that is, the second region) below the inner portion 161 will have a first amount (also That is, more than 90%) is directly emitted from the light-emitting element 100 through the second region 1333, and the second amount (that is, less than 10%) is emitted to the light-absorbing layer 18 and absorbed by the light-absorbing layer 18. In one embodiment, more than 50% of the second amount of light is absorbed by the light absorbing layer 18. In addition, the light from the active layer 132 will not be emitted outside the light-emitting element 100 through the first region 1332 and the side wall 1331. The ratio of the area of the second region 1333 to the area of the upper surface of the light emitting stack 13 is between 10% and 90%, that is, the light emitting area is defined as 10% to 90% of the area of the light emitting stack 13. The light absorbing layer 18 includes a single layer or a plurality of layers, and has a thickness greater than 300 Å. The material of the light absorbing layer 18 includes titanium (Ti), chromium (Cr), nickel (Ni), or a combination thereof. The first electrode 16 includes a metal or a metal alloy. Metals include copper (Cu), aluminum (Al), gold (Au), lanthanum (La), or silver (Ag). Metal alloys include germanium gold (GeAu), beryllium gold (BeAu), chrome gold (CrAu), silver titanium (AgTi), copper tin (CuSn), copper zinc (CuZn), copper cadmium (CuCd), tin lead antimony (Sn -Pb-Sb), tin-lead-zinc (Sn-Pb-Zn), nickel-tin (NiSn), or nickel-cobalt (NiCo). The light absorbing layer 18 can be used as a pad, and an electrical connection can be formed under a current operation through a wire bond and an external structure (not shown), such as a package substrate.

In this embodiment, the position where the reflective layer 12 is covered in the bonding layer 11 corresponds to the position of the second region 1333 on the upper surface of the light-emitting stack 13. When light from the active layer 132 strikes the substrate 10, the light may be reflected by the reflective layer 12 and directed toward the second-type semiconductor layer 133. Since part of the light is emitted only through the second region 1333 on the upper surface of the second type semiconductor layer 133, the area of the reflective layer 12 is substantially the same as that of the second region 1333 on the upper surface of the second type semiconductor layer 133. In another embodiment, the area of the reflective layer 12 may be larger than the area of the second region 1333 on the upper surface of the second type semiconductor layer 133.

3 and 4 are a light emitting device 200 according to a second embodiment of the present invention. FIG. 3 is a top view of the light emitting element 200. FIG. 4 is a cross-sectional view of the light-emitting element 200 along BB ′. The structure of the light-emitting element 200 is similar to that of the light-emitting element 100 in the first embodiment, except that the inner portion 161 of the light-emitting element 200 has two sub-inner portions 1611 and 1612. The plurality of first extensions 1631 are electrically connected to the two inner portions 1611 and 1612 and the outer portion 162. Any one of the two sub-interiors 1611, 1612 is electrically connected to the outer 162 through a plurality of second extensions 1632. The first extending portions 1631 and the second extending portions 1632 are staggered. The outer portion 162 includes a plurality of convex portions 164. Here, the second region 1333 is defined by the outer portion 162 and the convex portion 164, and the light from the active layer 132 is emitted from the light emitting element 200 only through the second region 1333. As shown in FIG. 4, the ohmic contact layer 15 is located between the two sub-interiors 1611, 1612 and the light emitting stack 13 to provide an ohmic contact. The shape of the ohmic contact layer 15 is substantially the same as the two sub-interiors 1611, 1612 of the inner 161. The ohmic contact layer 15 is not formed between the outer portion 162 and the light emitting stack 13. In another embodiment (not shown), the ohmic contact layer 15 may be formed between the outer portion 162 and the light-emitting stack 13. The shape of the ohmic contact layer 15 is substantially the same as that of the outer portion 162. The shapes of the two sub-inners 1611, 1612 and the outer 162 of the inner 161 include a circle, a square, a quadrangle or a polygon. When the shapes of the two sub-inner portions 1611, 1612 and the outer portion 162 of the inner portion 161 are circular, they are mutually concentric circles. The ratio of the area of the second region 1333 to the area of the upper surface of the light-emitting stack 13 is between 10% and 90%. The number of the inside and the outside can be adjusted according to the embodiment. The larger the area of the second region 1333 outside the light emitting element through the second region 1333 of the light from the active layer 132, the larger the number of the inside 162 and the outside 162.

5A and 5B are a light emitting device 300 according to a third embodiment of the present invention. FIG. 5A is a top view of a light emitting device 300 according to a third embodiment of the present invention. FIG. 5B is a cross-sectional view of the light-emitting element 300 in FIG. 5A along XX ′. As shown in FIG. 5A, the light-emitting element 300 includes a light-emitting region and an electrode region surrounding the light-emitting region. The light-emitting region is located approximately in the center of the light-emitting element 300. The electrode region is a light-absorbing region, in other words, a non-light-emitting region. The shape of the light-emitting area in the top view is approximately a circle, but the shape of the light-emitting area is not limited thereto, and may be a polygon, such as a triangle or a square. Taking the shape of the light emitting area as a circle as an example, the light emitting area may be a circle with a diameter between 0.004 and 0.5 mm, and preferably a circle with a diameter between 0.001 and 0.2 mm. The structure of the light-emitting element 300 is similar to the structure of the light-emitting element 100 in the first embodiment, except that the light-emitting element 300 includes a trench 20, and the trench 20 separates an epitaxial structure 33 of the light-emitting element 300 into a first semiconductor structure 22 and a first semiconductor structure 22. Two semiconductor structures 24, wherein the first semiconductor structure 22 is substantially circular in a top view, and the second semiconductor structure 24 surrounds the first semiconductor structure 22. The first semiconductor structure 22 and the second semiconductor structure 24 have substantially the same epitaxial structure 33, and their material composition and stacking structure are substantially the same. The epitaxial structure 33 includes a first type semiconductor layer 331 and a second type semiconductor layer. 333, and an active layer 332 is located between the first type semiconductor layer 331 and the second type semiconductor layer 333. The trench 20 separates the active layer 332 and the second type semiconductor layer 333 of the first semiconductor structure 22 from the active layer 332 and the second type semiconductor layer 333 of the second semiconductor structure 24, but the first semiconductor structure 22 The semiconductor layer 331 is connected to the first semiconductor layer 331 of the second semiconductor structure 24. The first semiconductor structure 22 operates under a current, and the active layer 332 of the first semiconductor structure 22 can emit a first light having a first dominant wavelength; the second semiconductor structure 24 operates under a current, and the second semiconductor structure 24 The active layer 332 can emit a second light having a second dominant wavelength, wherein the first dominant wavelength and the second dominant wavelength are in the same wavelength range, or the dominant wavelength of the first light and the dominant wavelength of the second light Substantially the same, for example, the first dominant wavelength and the second dominant wavelength may be red light having a wavelength between 610 nm and 650 nm, green light having a wavelength between 530 nm and 570 nm, or a wavelength between 450 Blue light between nm and 490 nm.

In order to prevent the first light emitted from the active layer 332 of the first semiconductor structure 22 from leaking to the second semiconductor structure 24, the trench 20 includes one or more insulating layers. The insulating material of the insulating layer can absorb the first light or reflect the first light. Light. The insulating material includes an organic polymer material or an inorganic material.

A portion of the reflective layer 12 overlying the first semiconductor structure 22 and a portion overlying the second semiconductor structure 24 of one of the light-emitting elements 300 are connected. In a top view of one of the light-emitting elements 300, the position of the reflective layer 12 is It is arranged in a manner corresponding to the position of the light emitting area and the area of the reflective layer 12 may be the same as or larger than the area of the light emitting area. When the first light and / or the second light from the active layer 332 is directed toward the substrate 10, the first light and / or the second light may be reflected by the reflective layer 12 and directed toward the second type semiconductor layer 333, and close to the second type semiconductor layer 333. One type of semiconductor layer 333 emits light. Specifically, substantially all of the first light and the second light are emitted from a top surface 33S of one of the light-emitting elements 300. In one embodiment, the top surface 33S can be formed into a roughened surface by etching or embossing to improve the light emitting efficiency of the light emitting device 300.

As shown in FIG. 5A, the electrode region includes a plurality of external electrode structures, and the plurality of external electrode structures substantially surround the second semiconductor structure 24. The plurality of external electrode structures include a first external electrode structure 28 and a second external electrode structure 38. Each of the external electrode structures 28 and 38 can be used as a pad, and a wire bond and an external A structure (not shown), such as a package substrate, forms an electrical connection under a current operation. The first external electrode structure 28 and the second external electrode structure 38 include an insulating layer 19 and a conductive layer 281, respectively. The insulating layer 19 is located between the second semiconductor structure 24 and the conductive layer 281. The material of the conductive layer 281 includes a metal or a metal alloy. Metals include lanthanum (La), copper (Cu), aluminum (Al), gold (Au), or silver (Ag). Metal alloys include germanium gold (GeAu), beryllium gold (BeAu), chrome gold (CrAu), silver titanium (AgTi), copper tin (CuSn), copper zinc (CuZn), copper cadmium (CuCd), tin lead antimony (Sn -Pb-Sb), tin-lead-zinc (Sn-Pb-Zn), nickel-tin (NiSn), or nickel-cobalt (NiCo).

As shown in FIG. 5A, the number of the first external electrode structures 28 is one pair, and the number of the second external electrode structures 38 is one pair, in which a pair of first external electrode structures 28 are opposed to each other and a pair of second external electrodes The structures 38 are opposed to each other. The plurality of first external electrode structures 28 and the plurality of second external electrode structures 38 are staggered with each other. However, the number and arrangement of the first external electrode structures 28 and the second external electrode structures 38 are not as described above. For restrictions.

As shown in FIG. 5A, the light emitting element 300 includes a plurality of extended electrodes on the epitaxial structure 33. Specifically, the plurality of extension electrodes include a first extension electrode 221 on the first semiconductor structure 22 and a second extension electrode 241 on the second semiconductor structure 24. The shape of the first extension electrode 221 or the second extension electrode 241 includes The ring shape, but in order to achieve the purpose of uniform current diffusion, the number and shape of the first extension electrode 221 and the second extension electrode 241 are not limited by the above and the figures.

As shown in FIG. 5A, the light-emitting element 300 includes a first connection electrode 223 to connect the first extension electrode 221 and the first external electrode structure 28, and a second connection electrode 243 to connect the second extension electrode 241 and the second external electrode structure. 38.

The light-emitting element 300 may optionally include an ohmic contact layer between the extension electrode, such as the first extension electrode 221, the second extension electrode 241, and the epitaxial structure 33. As shown in FIG. 5B, the light emitting device 300 includes a first ohmic contact layer 222 between the first extension electrode 221 and the second type semiconductor layer 333; and a second ohmic contact layer 242 between the second extension electrode 241 and the first Between two type semiconductor layers 333. In another embodiment, the light emitting device 300 may include an ohmic contact layer 362 between the conductive layer 281 of the first external electrode structure 28 and the second conductive semiconductor layer 333 and / or between the second external electrode structure 38 Between the conductive layer 281 and the second-type semiconductor layer 333. The shapes of the ohmic contact layers 222 and 242 are substantially the same as those of the extension electrodes. By the ohmic contact layers 222, 242, and 362, the contact resistance between the extension electrode and the second-type semiconductor layer 333 and the contact resistance between the conductive layer 281 and the second-type semiconductor layer 333 can be reduced.

As shown in FIG. 5B, the light-emitting element 300 includes a lower electrode 37 formed on a substrate 10. The lower electrode 37 can be electrically connected to the first type semiconductor layer 331 of the first semiconductor structure 22 and the first type semiconductor layer 331 of the second semiconductor structure 24 at the same time to form a light-emitting element having a vertical electrode. The substrate 10 is a conductive material The material of the substrate 10 includes a semiconductor material or a metal material.

As shown in FIG. 5A, the first external electrode structure 28 in the electrode region can be used as a first electrode group to receive a first current value, and form a current path with the lower electrode 37 to drive the first semiconductor structure 22 to emit A first light having a first brightness; the second external electrode structure 38 is different from the first electrode group and can be used as a second electrode group for receiving a second current value to drive the second semiconductor structure 24 to emit a A second light having a second brightness. The magnitude of the first brightness and the second brightness can be adjusted by the magnitude of the first current value and the second current value, and also by the sizes of the first semiconductor structure 22 and the second semiconductor structure 24, such as the first semiconductor structure 22 The area of the active layer 332 of the second semiconductor structure 24 is adjusted. For example, when the area of the active layer 332 of the first semiconductor structure 22 is smaller than the area of the active layer 332 of the second semiconductor structure 24 and the first current value is equal to the second current value, the first brightness will be greater than the second brightness. When the area of the active layer 332 of the first semiconductor structure 22 is equal to the area of the active layer 332 of the second semiconductor structure 24 and the first current value is greater than the second current value, the first brightness will be greater than the second brightness.

The first electrode group and the second electrode group may receive current values individually or simultaneously. As shown in FIG. 5A, when only the first electrode group, that is, the first external electrode structure 28, receives the first current value alone, only the first semiconductor structure 22 is driven to emit the first light. As shown in FIG. 6, when only the second electrode group, that is, the second external electrode structure 38, receives the second current value alone, only the second semiconductor structure 24 is driven to emit a second light. As shown in FIG. 7, when the first electrode group and the second electrode group, that is, the first external electrode structure 28 and the second external electrode structure 38 receive the first current value and the second current value, respectively, the first The semiconductor structure 22 and the second semiconductor structure 24 emit the first light and the second light at the same time.

Although the above drawings and descriptions only correspond to specific embodiments, however, the elements, implementations, design guidelines, and technical principles described or disclosed in each embodiment are inconsistent, contradictory, or difficult to implement together. In addition, we shall be free to refer, exchange, match, coordinate, or merge as needed.

Although the present invention has been described as above, it is not intended to limit the scope, implementation order, or materials and manufacturing methods of the present invention. Various modifications and changes made without departing from the spirit and scope of the invention.

10‧‧‧ substrate

11‧‧‧ bonding layer

12‧‧‧Reflective layer

13‧‧‧Light-emitting stack

131‧‧‧The first type semiconductor layer

132‧‧‧Active Level

133‧‧‧Second type semiconductor layer

1331‧‧‧ sidewall

1332‧‧‧ District 1

1333‧‧‧Second District

15‧‧‧ohm contact layer

16‧‧‧First electrode

161‧‧‧ Internal

1611, 1612‧‧‧times internal

1631‧‧‧First extension

1632‧‧‧Second Extension

162‧‧‧External

164‧‧‧ convex

17‧‧‧Second electrode

18‧‧‧ light-absorbing layer

181‧‧‧Part I

182‧‧‧Part Two

19‧‧‧ Insulation

100, 200, 300‧‧‧ light-emitting elements

20‧‧‧ Ditch

22‧‧‧First semiconductor structure

221‧‧‧First extension electrode

222‧‧‧first ohmic contact layer

223‧‧‧first connection electrode

24‧‧‧Second semiconductor structure

241‧‧‧Second extension electrode

242‧‧‧Second ohmic contact layer

243‧‧‧Second connection electrode

28‧‧‧First external electrode structure

38‧‧‧Second external electrode structure

281‧‧‧ conductive layer

33‧‧‧Epitaxial structure

33S‧‧‧Top

331‧‧‧The first type semiconductor layer

332‧‧‧Active Level

333‧‧‧Second type semiconductor layer

362‧‧‧ohm contact layer

37‧‧‧ lower electrode

FIG. 1 is a top view of a light emitting device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the light-emitting element of FIG. 1 along AA ′.

FIG. 3 is a top view of a light emitting device according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view of the light-emitting element of FIG. 3 along BB ′.

FIG. 5A is a top view of a light emitting device according to a third embodiment of the present invention.

FIG. 5B is a cross-sectional view of the light-emitting element of FIG. 5A along XX ′.

FIG. 6 is a top view of a light emitting device according to a third embodiment of the present invention.

FIG. 7 is a top view of a light emitting device according to a third embodiment of the present invention.

Claims (10)

A light-emitting element includes: a light-emitting stack including an active layer capable of emitting a light; a first electrode on the light-emitting stack; a contact layer between the first electrode and the light-emitting stack; And a reflective layer is located below the light emitting stack, and in a cross section of the light emitting element, the width of the reflective layer is smaller than the width of the light emitting stack. The light-emitting element according to item 1 of the scope of patent application, wherein the first electrode includes an inner portion and an outer portion, the upper surface has a first region and a second region, the first region corresponds to the outer portion and the first region The two regions correspond to the inside. In a top view of the light emitting element, the first region surrounds the second region, and the area of the reflective layer is greater than or equal to the area of the second region. According to the light-emitting element described in item 2 of the scope of patent application, the ratio of the area of the second region to the area of the upper surface is between 10% and 90%. The light-emitting element according to item 2 of the scope of patent application, wherein the contact layer is located between the inside of the first electrode and the light-emitting stack. . The light-emitting element according to item 2 of the patent application, wherein the second region includes a roughened surface. The light-emitting element according to item 2 of the scope of patent application, wherein the shape of the inside and the outside includes a circle. The light-emitting element according to item 1 of the scope of patent application, wherein in the top view of the light-emitting element, the shape of the first electrode includes a circle. The light-emitting element according to item 1 of the patent application scope, wherein the first electrode is formed on the upper surface and divides the upper surface into a first region and a second region, and the light is emitted from the second region to the light-emitting element. The light is not emitted from the first region outside the light emitting element. The light-emitting element according to item 4 of the scope of patent application, further includes a substrate located under the light-emitting stack; and a bonding layer located between the substrate and the reflective layer. The light-emitting element according to item 9 of the scope of patent application, wherein the bonding layer covers the reflective layer.