CN115132889A - Light-emitting diodes and light-emitting devices - Google Patents

Abstract

The invention relates to the technical field of semiconductor manufacturing, In particular to a light emitting diode which comprises an epitaxial structure, wherein the epitaxial structure is provided with a first surface and a second surface which are opposite, the epitaxial structure sequentially comprises an N-type semiconductor layer, a light emitting layer and a P-type semiconductor layer from the second surface to the first surface, the P-type semiconductor layer comprises a composite ohmic contact layer and a current expansion layer, the current expansion layer is positioned between the composite ohmic contact layer and the light emitting layer, and In and C are doped In the composite ohmic contact layer. Therefore, the crystal quality of the tail end contact layer can be improved, dislocation light absorption is reduced to improve the lighting effect, the routing quality is improved, and the quality of the light emitting diode is improved.

Description

Light-emitting diodes and light-emitting devices

technical field

The present invention relates to the technical field of semiconductor manufacturing, and in particular, to a light emitting diode and a light emitting device.

Background technique

A light-emitting diode (Light Emitting Diode, LED for short) is a semiconductor light-emitting element, usually made of semiconductors such as GaN, GaAs, GaP, GaAsP, etc., and its core is a PN junction with light-emitting characteristics. LED has the advantages of high luminous intensity, high efficiency, small size and long service life, and is considered to be one of the most potential light sources at present. LED has been widely used in lighting, monitoring and commanding, high-definition studio, high-end cinema, office display, conference interaction, virtual reality and other fields.

At present, in order to obtain a higher impurity concentration at the epitaxy tail end (such as the surface layer of the P-type semiconductor layer) to meet the purpose of making ohmic contacts in the chip manufacturing process to reduce the voltage, it is necessary to orient the epitaxy under the conditions of low temperature and special gas content. Doping (such as Mg and C), lower temperature and special gas conditions will cause quality deviation of the epitaxial layer at the tail end, more dislocations and light absorption affecting brightness, and quality abnormalities such as wire bonding due to chip contact diffusion. Therefore, how to grow and develop new epitaxial materials to overcome the above-mentioned defects is a key point to improve the luminous efficiency and quality, and it is also one of the technical problems to be solved urgently by those skilled in the art.

SUMMARY OF THE INVENTION

The present invention provides a light emitting diode including an epitaxial structure. The epitaxial structure has opposing first and second surfaces. The epitaxial structure includes an N-type semiconductor layer, a light-emitting layer and a P-type semiconductor layer in sequence from the second surface to the first surface. Wherein, the P-type semiconductor layer includes a composite ohmic contact layer and a current spreading layer. The current spreading layer is located between the composite ohmic contact layer and the light emitting layer. The composite ohmic contact layer is doped with In and C.

In some embodiments, the composite ohmic contact layer includes a first sublayer and a second sublayer, the second sublayer being located between the first sublayer and the current spreading layer.

In some embodiments, the thickness of the first sublayer is less than the thickness of the second sublayer.

In some embodiments, the material of the composite ohmic contact layer includes GaP.

In some embodiments, the concentration ratio of In to Ga in the composite ohmic contact layer is 1:1˜20:1.

In some embodiments, the concentration of In doped in the composite ohmic contact layer ranges from 1×10 ¹⁷ cm ⁻³ to 1×10 ²² cm ⁻³ .

In some embodiments, the concentration of In doped in the composite ohmic contact layer gradually decreases along the direction from the first surface to the second surface.

In some embodiments, the concentration of In doped in the composite ohmic contact layer is gradually increased along the direction from the first surface to the second surface.

In some embodiments, the material of the current spreading layer includes GaP.

In some embodiments, the current spreading layer is doped with Mg.

In some embodiments, the light emitting diode further includes an N-type electrode and a P-type electrode, the N-type electrode is electrically connected to the N-type semiconductor layer, and the P-type electrode is electrically connected to the P-type semiconductor layer.

In some embodiments, an ITO electrode is disposed between the P-type electrode and the P-type semiconductor layer.

In some embodiments, the emission wavelength of the light-emitting layer is 550-950 nm.

The present invention also provides a light-emitting device, which adopts the light-emitting diode provided in any of the above embodiments.

An embodiment of the present invention provides a light emitting diode and a light emitting device. By doping In and C into the composite ohmic contact layer, dislocation defects are filled and the crystal of the tail end contact layer (ie, the composite ohmic contact layer) is improved. quality, reduce the light absorption of dislocations to improve light efficiency, improve the quality of wire bonding, and then improve the quality of light-emitting diodes.

Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

FIG. 1 is a schematic structural diagram of a light emitting diode according to a first embodiment of the present invention;

Fig. 2 is the structural representation of composite ohmic contact layer;

3 is a schematic structural diagram of a light emitting diode provided by a second embodiment of the present invention;

4 to 5 are schematic structural views of the light-emitting diode shown in FIG. 3 at various stages in the manufacturing process;

6 is a schematic structural diagram of a light emitting diode provided by a third embodiment of the present invention;

FIG. 7 is a schematic diagram of the light effect of different In fluxes.

Reference number:

1, 2, 3 - light emitting diode; 10 - growth substrate; 12 - epitaxial structure; 121 - first surface; 122 - second surface; 123 - N-type semiconductor layer; 124 - light-emitting layer; 125 - P-type semiconductor layer 1251-composite ohmic contact layer; 1252-current spreading layer; 1253-P-type cover layer; 1254-transition layer; 1251a-first sublayer; 1251b-second sublayer; 1231-N-type window layer; 1233-N-type ohmic contact layer; 21-N-type electrode; 22-P-type electrode; 23-insulating layer; 24-ITO electrode; 25-metal reflection layer; 26-bonding layer; 27-substrate.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of the embodiments of the present invention, not all of the embodiments; the technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, this All other embodiments obtained by persons of ordinary skill in the art without creative work fall within the protection scope of the present invention.

In the description of the present invention, it should be understood that the terms "center", "lateral", "top", "bottom", "left", "right", "vertical", "horizontal", "top", " The orientation or positional relationship indicated by "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the indicated device or The components must have a particular orientation, or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "plurality" means two or more. In addition, the term "comprising" and any variations thereof mean "at least including".

Please refer to FIG. 1 and FIG. 2 , FIG. 1 is a schematic structural diagram of the light emitting diode 1 provided by the first embodiment of the present invention, and FIG. 2 is a structural schematic diagram of the composite ohmic contact layer 1251 . To achieve at least one of the aforementioned advantages or other advantages, a first embodiment of the present invention provides a light emitting diode 1 . As shown in the figures, the light emitting diode 1 may include an epitaxial structure 12 .

The epitaxial structure 12 has opposing first surfaces 121 and second surfaces 122 . In this embodiment, the first surface 121 and the second surface 122 of the epitaxial structure 12 are the upper surface and the lower surface, respectively. The epitaxial structure 12 includes an N-type semiconductor layer 123 , a light-emitting layer 124 and a P-type semiconductor layer 125 in order from the second surface 122 to the first surface 121 . In other words, the epitaxial structure 12 sequentially includes an N-type semiconductor layer 123 , a light-emitting layer 124 and a P-type semiconductor layer 125 from bottom to top, and the light-emitting layer 124 is located between the N-type semiconductor layer 123 and the P-type semiconductor layer 125 .

The N-type semiconductor layer 123 and the P-type semiconductor layer 125 may be respectively n-type or p-type doped to achieve at least supply of electrons or holes, respectively. The N-type semiconductor layer 123 may be doped with an n-type dopant such as Si, Ge, or Sn, and the P-type semiconductor layer 125 may be doped with a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. The N-type semiconductor layer 123 , the light-emitting layer 124 and the P-type semiconductor layer 125 can be specifically made of materials such as AlGaInN, GaN, AlGaN, AlInP, AlGaInP, GaAs or AlGaAs, etc. form. The N-type semiconductor layer 123 or the P-type semiconductor layer 125 includes a capping layer that provides electrons or holes, and may include other layer materials such as a current spreading layer, a window layer, or an ohmic contact layer, etc., depending on the doping concentration or component content. Make settings for different layers. The light-emitting layer 124 is a region that provides electrons and holes recombination to provide light radiation. Different materials can be selected according to different light-emitting wavelengths. The light-emitting layer 124 can be a periodic structure of single quantum well or multiple quantum wells. By adjusting the composition ratio of the semiconductor material in the active layer light-emitting layer 124, it is desired to radiate light of different wavelengths. In this embodiment, the epitaxial structure 12 is preferably composed of AlGaAs-based or AlGaInP-based materials. The emission wavelength of the light-emitting layer 124 is preferably 550 to 950 nm.

The P-type semiconductor layer 125 includes a composite ohmic contact layer 1251 and a current spreading layer 1252 . The current spreading layer 1252 is located between the composite ohmic contact layer 1251 and the light emitting layer 124 , and the current spreading layer 1252 can play a current spreading effect to improve the optoelectronic characteristics of the light emitting diode 1 . The composite ohmic contact layer 1251 is used to form a good ohmic contact with the electrodes, which is beneficial to the input and output of current. The composite ohmic contact layer 1251 is doped with In (indium) and C (carbon), that is, on the basis of C doping in the low-temperature composite ohmic contact layer 1251 , an appropriate amount of In is added to fill dislocation defects and reduce light absorption. By doped In and C in the composite ohmic contact layer 1251, dislocation defects can be filled, so as to solve the problem that the crystal quality of the existing tail contact layer is too low, that is, to improve the tail contact layer (ie, the composite ohmic contact layer) 1251) crystal quality, reduce the light absorption of dislocations to improve the light efficiency, improve the quality of the wire, and then improve the quality of the light-emitting diode 1. This optimized solution doped with In and C is more suitable for the light-emitting diode 1 with the light-emitting wavelength of the light-emitting layer 124 being 550-950 nm.

In some embodiments, the material of the composite ohmic contact layer 1251 may include GaP, that is, the GaP composite ohmic contact layer 1251 is doped with In and C to fill dislocation defects. The concentration ratio of In to Ga in the composite ohmic contact layer 1251 is 1:1˜20:1, which is beneficial to improve the crystal quality of the composite ohmic contact layer 1251 . The concentration range of In doped in the composite ohmic contact layer 1251 is 1×10 ¹⁷ cm ^-3 to 1×10 ²² cm ^-3 , so as to avoid In entering the current spreading layer 1252 due to the high In concentration, thereby affecting the light-emitting diode 1 The light efficiency and quality are excellent, and it can also provide a better effect of filling dislocation defects and reducing light absorption.

In some embodiments, the concentration of In doped in the composite ohmic contact layer 1251 gradually decreases along the direction from the first surface 121 to the second surface 122 , which can provide a better effect of filling dislocation defects and reducing light absorption. However, the present patent is not limited to this. The concentration of In doped in the composite ohmic contact layer 1251 can also be gradually increased along the direction from the first surface 121 to the second surface 122, which can also provide better reduction of filling dislocation defects. light-absorbing effect.

In some embodiments, the material of the current spreading layer 1252 may include GaP. The current spreading layer 1252 is doped with Mg, and Mg can provide P-type holes, increase the number of carriers for current spreading, reduce VF (forward voltage), and improve the current spreading capability.

In some embodiments, as shown in FIG. 1 , the P-type semiconductor layer 125 may further include a P-type cladding layer 1253 and a transition layer 1254 . The P-type cladding layer 1253 is located between the transition layer 1254 and the light emitting layer 124 . The transition layer 1254 is located on the P-type cladding layer 1253 and the current spreading layer 1252 . The N-type semiconductor layer 123 may include an N-type window layer 1231 and an N-type capping layer 1232 . The N-type cladding layer 1232 is located between the N-type window layer 1231 and the light-emitting layer 124 . In other words, along the direction from the second surface 122 to the first surface 121 of the epitaxial structure 12 are the N-type window layer 1231 , the N-type cladding layer 1232 , the light-emitting layer 124 , the P-type cladding layer 1253 , the transition layer 1254 , and the current spreading layer. 1252 and composite ohmic contact layer 1251. The P-type capping layer 1253 can provide the light emitting layer 124 with hole minority carriers and electrons for recombination light emission. The transition layer 1254 is used to allow the P-type capping layer 1253 to smoothly transition to the current spreading layer 1252, thereby reducing lattice defects and potential barriers, reducing voltage, and reducing light absorption points. The N-type window layer 1231 can be used as a process roughening layer. The N-type cladding layer 1232 is used to supply electrons for the light-emitting layer 124 to emit light.

In some embodiments, as shown in FIG. 2, the composite ohmic contact layer 1251 may include a first sublayer 1251a and a second sublayer 1251b. The second sublayer 1251b is located between the first sublayer 1251a and the current spreading layer 1252 . In other words, along the direction from the second surface 122 to the first surface 121 of the epitaxial structure 12 are the current spreading layer 1252 , the second sublayer 1251b and the first sublayer 1251a in order.

In order to prevent In in the composite ohmic contact layer 1251 from entering the current spreading layer 1252 of higher quality, causing defects to affect the current spreading effect of the current spreading layer 1252, thereby affecting the brightness of the light emitting diode 1, the thickness of the first sublayer 1251a is less than The thickness of the second sub-layer 1251b, the quality of the growth of the second sub-layer 1251b is higher than that of the first sub-layer 1251a. The second sub-layer 1251b acts as a confinement layer of In, that is, restricts the entry of In into the current spreading layer 1252 under the composite ohmic contact layer 1251. If the thickness of the first sub-layer 1251a is too thick or the doped In concentration is too high, In will enter The current spreading layer 1252 thus affects the light efficiency and quality of the light emitting diode 1 . Preferably, the thickness of the first sub-layer 1251a ranges from 200 to 1500 angstroms. Preferably, the concentration of In doped in the first sublayer 1251a ranges from 1×10 ¹⁷ cm ⁻³ to 0.5×10 ²² cm ⁻³ .

Please refer to FIG. 3 , which is a schematic structural diagram of a light emitting diode 2 according to a second embodiment of the present invention. To achieve at least one of the aforementioned advantages or other advantages, a second embodiment of the present invention provides a light emitting diode 2 . Compared with the light emitting diode 1 shown in FIG. 1 , the light emitting diode 2 of this embodiment further includes an N-type electrode 21 , a P-type electrode 22 , an insulating layer 23 , an ITO electrode 24 , a metal reflective layer 25 , and a bonding layer 26 , and the substrate 27 . The light emitting diode 2 is a vertical structure light emitting diode 2 . The N-type electrode 21 and the P-type electrode 22 are respectively located on the side of the second surface 122 and the first surface 121 of the epitaxial structure 12 . The N-type electrode 21 is electrically connected to the N-type semiconductor layer 123 , and the P-type electrode 22 is electrically connected to the P-type semiconductor layer 125 . Specifically, along the direction from the first surface 121 to the second surface 122 of the epitaxial structure 12 are the P-type electrode 22 , the substrate 27 , the bonding layer 26 , the metal reflective layer 25 , the ITO electrode 24 , the insulating layer 23 , the P-type electrode 22 , the Type semiconductor layer 125 , light emitting layer 124 , N type semiconductor layer 123 , and N type electrode 21 . An N-type ohmic contact layer 1233 is further disposed between the N-type electrode 21 and the N-type window layer 1231 to form a good ohmic contact, which is beneficial to current transmission.

A method for manufacturing the light emitting diode 2 shown in FIG. 3 is disclosed below. Please refer to FIGS. 4 to 5 . FIGS. 4 to 5 are schematic structural diagrams of the light emitting diode 2 shown in FIG. 3 at various stages in the manufacturing process. .

First, referring to FIG. 4, a growth substrate 10 is provided. Next, an N-type semiconductor layer 123 , a light-emitting layer 124 and a P-type semiconductor layer 125 are grown sequentially on the growth substrate 10 . Specifically, the N-type semiconductor layer 123 includes an N-type ohmic contact layer 1233 , an N-type window layer 1231 and an N-type capping layer 1232 that are sequentially stacked from bottom to top. The P-type semiconductor layer 125 includes a P-type cladding layer 1253, a transition layer 1254, a current spreading layer 1252, and a composite ohmic contact layer 1251 that are sequentially stacked from bottom to top. The composite ohmic contact layer 1251 is doped with In and C.

Next, as shown in FIG. 5 , the insulating layer 23 is first formed under the P-type semiconductor layer 125, and the insulating layer 23 is etched to form an opening to facilitate electrical conduction. A thin ITO electrode 24 is formed at the opening of the insulating layer 23 and on the surface of the insulating layer 23 . The ITO electrode 24 is located between the P-type electrode 22 and the P-type semiconductor layer 125, and a good ohmic contact can be formed between the ITO electrode 24 and the composite ohmic contact layer 1251 to enhance the input and output of current. The ITO electrode is made of transparent conductive material, and the transparent conductive material includes indium tin oxide (ITO). Then, a metal reflective layer 25 is formed under the ITO electrode 24 , and the metal reflective layer 25 can reflect the light emitted by the light-emitting layer 124 to improve the overall light-emitting effect. Then, the metal reflective layer 25 is connected to the substrate 27 through the bonding layer 26 . Then, a P-type electrode 22 is provided on the side of the substrate 27 away from the bonding layer 26 ; finally, the growth substrate 10 is removed, and an N-type electrode 21 is formed on the N-type semiconductor layer 123 .

The above is only a disclosed method for manufacturing the light emitting diode 2 shown in FIG. 3 , and the present case is not limited to this, but is only used to illustrate a method of manufacturing the light emitting diode 2 .

Please refer to FIG. 6 , which is a schematic structural diagram of a light emitting diode 3 according to a third embodiment of the present invention. To achieve at least one of the aforementioned advantages or other advantages, a third embodiment of the present invention provides a light emitting diode 3 . The N-type electrode 21 and the P-type electrode 22 of the light emitting diode 3 in this embodiment are located on the same side of the epitaxial structure 12 , that is, the N-type electrode 21 and the P-type electrode 22 are both located on the first surface 121 of the epitaxial structure 12 . side. The N-type electrode 21 is electrically connected to the N-type semiconductor layer 123 , and the P-type electrode 22 is electrically connected to the P-type semiconductor layer 125 .

It is supplemented that, regarding the manner in which the composite ohmic contact layer 1251 is doped with In and C, the doping of In and C can be achieved by feeding a growth source containing In and C during the epitaxial growth process, or it can be done during the growth process. After the composite ohmic contact layer 1251 is completed, In and C are actively implanted into the composite ohmic contact layer 1251, such as ion implantation. However, this patent is not limited to this, and the method of doping In into the composite ohmic contact layer 1251 can also be achieved by diffusing In into the composite ohmic contact layer 1251 from the ITO electrode 24 when the ITO electrode 24 is plated.

Please refer to FIG. 7, which is a schematic diagram of the light effect of different In fluxes. The left ordinate in Fig. 7 is lop (optical output power), the right ordinate is wpe (electro-optical conversion efficiency), and the abscissa is the mixed In flux. The In flow rate of 0 corresponds to the LED products of the prior art. Under the same test condition of 350mA, the light efficiency (lop and wpe) of the light-emitting diode 1 of the present invention is improved compared with the LED products of the prior art through different In flow rates, for example, the light output power is increased from 402 to 433mW , the light efficiency is increased by about 8%, and the quality of the light-emitting diode 1 is improved.

The present invention also provides a light-emitting device, which adopts the light-emitting diodes 1, 2, and 3 provided in any of the above embodiments.

To sum up, the light emitting diodes 1 , 2 , 3 and the light emitting device provided by an embodiment of the present invention can fill the dislocation defects and improve the tail end by doping In and C in the composite ohmic contact layer 1251 . The crystal quality of the contact layer (ie the composite ohmic contact layer 1251 ) reduces the light absorption of dislocations to improve light efficiency, improve the quality of wire bonding, and further improve the quality of LEDs 1 , 2 and 3 .

In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, without simultaneously solving the problems in the prior art or All technical issues listed in the background art. Those skilled in the art should understand that anything not mentioned in a claim should not be construed as a limitation on the claim.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (14)

1. A light-emitting diode, characterized in that: the light-emitting diode comprises: an epitaxial structure, having an opposite first surface and a second surface, the epitaxial structure including an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer in sequence along the direction from the second surface to the first surface; Wherein, the P-type semiconductor layer includes a composite ohmic contact layer and a current spreading layer, the current spreading layer is located between the composite ohmic contact layer and the light-emitting layer, and the composite ohmic contact layer is doped with In and C . 2 . The light emitting diode according to claim 1 , wherein the composite ohmic contact layer comprises a first sublayer and a second sublayer, and the second sublayer is located between the first sublayer and the current between extension layers. 3. The light emitting diode according to claim 2, wherein the thickness of the first sub-layer is smaller than the thickness of the second sub-layer. 4. The light emitting diode according to claim 1, wherein the material of the composite ohmic contact layer comprises GaP. 5 . The light-emitting diode according to claim 4 , wherein the concentration ratio of In to Ga in the composite ohmic contact layer is 1:1˜20:1. 6 . 6 . The light-emitting diode according to claim 1 , wherein the concentration of In doped in the composite ohmic contact layer ranges from 1×10 ¹⁷ cm ⁻³ to 1×10 ²² cm ⁻³ . 7 . 7 . The light emitting diode according to claim 1 , wherein the concentration of In doped in the composite ohmic contact layer gradually decreases along the direction from the first surface to the second surface. 8 . 8 . The light emitting diode according to claim 1 , wherein the concentration of In doped in the composite ohmic contact layer gradually increases along the direction from the first surface to the second surface. 9 . 9 . The light emitting diode of claim 1 , wherein the material of the current spreading layer comprises GaP. 10 . 10 . The light-emitting diode of claim 1 , wherein the current spreading layer is doped with Mg. 11 . 11. The light emitting diode according to claim 1, wherein the light emitting diode further comprises an N-type electrode and a P-type electrode, the N-type electrode is electrically connected to the N-type semiconductor layer, and the P-type electrode is electrically connected to the N-type semiconductor layer. The P-type semiconductor layer is connected. 12 . The light emitting diode of claim 11 , wherein an ITO electrode is disposed between the P-type electrode and the P-type semiconductor layer. 13 . 13 . The light-emitting diode according to claim 1 , wherein the light-emitting wavelength of the light-emitting layer is 550-950 nm. 14 . 14. A light-emitting device, wherein the light-emitting device adopts the light-emitting diode according to any one of claims 1 to 13.

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