A preparation method of red-yellow GaAs-based LED chips and LED chips

Abstract

The present invention provides a method for preparing a red-yellow GaAs LED and a chip, the method comprising: providing a GaAs substrate; growing an epitaxial layer on the GaAs substrate; sequentially growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer, and evaporating AuBe on the second carbon-doped GaP layer; diffusing Be ions in the AuBe into the second carbon-doped GaP layer by annealing, and then etching the evaporated AuBe to expose the second carbon-doped GaP layer; growing a CB layer on the second carbon-doped GaP layer, and providing a mirror metal layer on the CB layer. Compared with the prior art, the present invention avoids the high overall voltage of the chip while taking into account high light extraction efficiency.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a method for preparing a red-yellow GaAs-based LED chip and an LED chip. Background Art

[0002] The preparation of the LED mirror is an extremely important process in the red-yellow GaAs-based LED flip-chip reverse-polarity vertical structure product. Its main purpose is to improve the chip brightness through the prepared mirror.

[0003] When the red-yellow GaAs-based LED chip MQW (quantum well) emits light, the main application is forward light. Due to the high light absorption characteristics of the GaAs material, the light emitted downward will be absorbed by GaAs and cannot be reflected back to the front. Therefore, the light emission of the GaAs-based chip without a mirror layer is mainly forward light emission. To improve the light emission efficiency and reduce light absorption, the red-yellow GaAs product has a unique flip-chip reverse-polarity product. Its main feature is to add a set of mirror structures below the epitaxy by replacing different substrates, so that the light below can be reflected back to the front by the mirror structure when the MQW (quantum well) emits light, thereby achieving the effect of improving the brightness.

[0004] In the prior art, the epitaxy of the red-yellow GaAs-based LED chip replaces the substrate to form an ODR (omnidirectional reflector) structure by adding a mirror and a dielectric layer, thereby improving the light emission brightness of the LED chip. However, as the dielectric layer SiO2 is not conductive, although the CB hole is etched as an ohmic contact channel, it will still increase the overall voltage of the chip. Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a red-yellow GaAs-based LED chip and a preparation method, aiming to solve the problem of the high overall voltage of the LED chip in the prior art.

[0006] The embodiment of the present invention is implemented as follows. A method for preparing a red-yellow GaAs-based LED chip, the method includes:

[0007] Providing a GaAs substrate;

[0008] Growing an epitaxial layer on the GaAs substrate;

[0009] Growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer in sequence, and evaporating AuBe on the second carbon-doped GaP layer;

[0010] Annealing to diffuse the Be ions in the AuBe into the second carbon-doped GaP layer, and then etching the evaporated AuBe to expose the second carbon-doped GaP layer;

[0011] Grow a CB layer on the second carbon-doped GaP layer, and dispose a mirror metal layer on the CB layer.

[0012] Further, for the above-mentioned red-yellow GaAs-based LED chip and preparation method, in the step of annealing to diffuse Be ions in the AuBe into the second carbon-doped GaP layer and then etching the evaporated AuBe to expose the second carbon-doped GaP layer, the proportion of the Be ions is 15% - 20%.

[0013] Further, for the above-mentioned red-yellow GaAs-based LED chip and preparation method, the step of growing a first carbon-doped GaP layer and a second carbon-doped GaP layer in sequence on the epitaxial layer and evaporating AuBe on the second carbon-doped GaP layer includes:

[0014] Grow a first carbon-doped GaP layer with a set doping concentration on the epitaxial layer, then transition to a transition GaP layer with a set concentration in steps of each preset doping concentration, then continue to grow a second carbon-doped GaP layer with a set doping concentration, and evaporate AuBe on the second carbon-doped GaP layer.

[0015] Further, for the above-mentioned red-yellow GaAs-based LED chip and preparation method, the set doping concentration of the first carbon-doped GaP layer is 3e16 cm -3 , the set concentration of the second carbon-doped GaP layer is 3e17 cm -3 , the set concentration of the transition GaP layer is 3e17 cm -3 , and the preset doping concentration is 3e1 cm -3 .

[0016] Further, for the above-mentioned red-yellow GaAs-based LED chip and preparation method, in the step of annealing to diffuse Be ions in the AuBe into the second carbon-doped GaP layer and then etching the evaporated AuBe to expose the second carbon-doped GaP layer, the AuBe is etched with a gold etchant.

[0017] Further, for the above-mentioned red-yellow GaAs-based LED chip and preparation method, the step of growing a CB layer on the second carbon-doped GaP layer and disposing a mirror metal layer on the CB layer includes:

[0018] Grow SiO 2 on the second carbon-doped GaP layer as the CB layer, photolithograph a CB pattern on the CB layer, then wet-etch a CB hole, and then perform mirror metal evaporation on the CB layer to obtain a mirror metal layer.

[0019] Further, in the above red-yellow GaAs-based LED chip and preparation method, in the step of sequentially growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer and evaporating AuBe on the second carbon-doped GaP layer, the growth thicknesses of the first carbon-doped GaP layer and the second carbon-doped GaP layer are the same.

[0020] Further, in the above red-yellow GaAs-based LED chip and preparation method, the growth thicknesses of both the first carbon-doped GaP layer and the second carbon-doped GaP layer are 5000 Å.

[0021] Further, in the above red-yellow GaAs-based LED chip and preparation method, in the step of sequentially growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer and evaporating AuBe on the second carbon-doped GaP layer, the evaporation thickness of the AuBe is 4000 Å.

[0022] Another object of the present invention is to provide a red-yellow GaAs-based LED chip prepared by the above preparation method.

[0023] Compared with the prior art, by setting a first carbon-doped GaP layer and a second carbon-doped GaP layer, and then evaporating AuBe in the second carbon-doped GaP layer, the Be ions in the AuBe are diffused and incorporated into the GaP second carbon-doped GaP layer through an annealing process, so that the conductivity of the GaP layer is increased, and the barrier of the highly doped epitaxial structure is extremely thin, and electrons can directly penetrate the barrier to achieve an ohmic contact effect. The grown CB layer and the mirror metal layer on the CB layer form a reflection structure to realize the reflection of the light of the chip, which not only protects the GaP layer with higher conductivity to reduce the overall voltage of the chip, but also can perform specular reflection to improve the light extraction efficiency. Description of the Drawings

[0024] Figure 1 It is a flowchart of the preparation method of the red-yellow GaAs-based LED chip in the first embodiment of the present invention;

[0025] Figure 2 It is a schematic structural diagram of the red-yellow GaAs-based LED chip in the second embodiment of the present invention. Detailed Embodiments

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] In addition, the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. In the detailed description and claims, a list of items connected by the term "one of" may mean any one of the listed items. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements. In the detailed description and claims, a list of items connected by the term "at least one of", "at least one kind of", or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" or "at least one of A or B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" or "at least one of A, B, or C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0028] Example 1

[0029] Please refer to Figure 1 , which is a method for preparing a red-yellow GaAs-based LED chip provided in the first embodiment of the present invention. This method includes steps S10 to S14.

[0030] Step S10: Provide a GaAs substrate.

[0031] Step S11: Grow an epitaxial layer on the GaAs substrate.

[0032] Specifically, as an implementation manner of the epitaxial layer, the growth process of the epitaxial layer is as follows:

[0033] Grow GaAs as a buffer layer on the GaAs substrate layer;

[0034] Grow GaInP as a blocking layer on the buffer layer;

[0035] Grow GaAs as an N-contact layer on the blocking layer;

[0036] Grow GaInP as an N-transition layer on the N-contact layer;

[0037] Grow AlxGaInP as an N-current spreading layer on the N-transition layer;

[0038] Growing N-AlInP on the N-current spreading layer provides electrons;

[0039] Growing AlGaInP on the N-AlInP layer serves as the N-blocking layer;

[0040] Growing MQW quantum wells on the N-blocking layer serves as the light-emitting layer;

[0041] Growing AlGaInP on the MQW quantum wells serves as the P-blocking layer;

[0042] Growing P-AlInP on the P-blocking layer provides holes;

[0043] Growing AlGaInP on the P-AlInP serves as the transition layer.

[0044] In step S12, a first carbon-doped GaP layer and a second carbon-doped GaP layer are sequentially grown on the epitaxial layer, and AuBe is evaporated on the second carbon-doped GaP layer.

[0045] Correspondingly, a first carbon-doped GaP layer and a second carbon-doped GaP layer are sequentially grown on the transition layer, and AuBe is evaporated on the second carbon-doped GaP layer. Specifically, during growth, a first carbon-doped GaP layer with a set doping concentration is grown on the epitaxial layer, then it transitions to a transition GaP layer with a set concentration in steps of each preset doping concentration, and then a second carbon-doped GaP layer with a set doping concentration is continuously grown, and AuBe is evaporated on the second carbon-doped GaP layer.

[0046] When specifically implementing this embodiment, the set doping concentration of the first carbon-doped GaP layer is 3e16 cm -3 , the set concentration of the second carbon-doped GaP layer is 3e17 cm -3 , the set concentration of the transition GaP layer is 3e17 cm -3 , and the preset doping concentration is 3e1 cm -3 . A first carbon-doped GaP layer with a doping concentration of 3e16 cm -3 is grown on the epitaxial layer, then it transitions to a transition GaP layer with a concentration of 3e17 cm -3 in steps of each 3e1 cm -3 , and then a second carbon-doped GaP layer with a doping concentration of 3e17 cm -3 is continuously grown, and AuBe is evaporated on the second carbon-doped GaP layer.

[0047] Furthermore, the growth thicknesses of the first carbon-doped GaP layer and the second carbon-doped GaP layer are the same. When specifically implementing this embodiment, the growth thicknesses of both the first carbon-doped GaP layer and the second carbon-doped GaP layer are 5000 Å, and the evaporation thickness of AuBe is 4000 Å.

[0048] In addition, in some preferred embodiments of the present invention, not only AuBe is evaporated on the second carbon-doped GaP layer, but AuGe can also be introduced.

[0049] Step S13: Anneal to diffuse Be ions in the AuBe into the second carbon-doped GaP layer, and then etch the evaporated AuBe to expose the second carbon-doped GaP layer.

[0050] Among them, the proportion of Be ions is 15% - 20%. In some alternative embodiments of the present invention, the proportion of Be ions can be 15%, 18%, 19%, or 20%.

[0051] Step S14: Grow a CB layer on the second carbon-doped GaP layer, and set a mirror metal layer on the CB layer.

[0052] Specifically, SiO 2 is grown as the CB layer on the second carbon-doped GaP layer. Then, a CB pattern is lithographed on this CB layer, and then CB holes are etched by wet etching. Finally, mirror metal evaporation is performed on the CB layer to obtain the mirror metal layer. Among them, the mirror metal includes but is not limited to Au, Ag, and Al.

[0053] In summary, for the preparation method of the red-yellow GaAs-based LED chip in the above embodiments of the present invention, by setting the first carbon-doped GaP layer and the second carbon-doped GaP layer, and then evaporating AuBe in the second carbon-doped GaP layer, the Be ions in the AuBe are diffused and incorporated into the GaP second carbon-doped GaP layer through the annealing process, which increases the conductivity of the GaP layer. And the high-doped epitaxial structure has an extremely thin barrier, and electrons can directly penetrate the barrier to achieve an ohmic contact effect. The grown CB layer and the mirror metal layer on the CB layer form a reflection structure to realize the reflection of the light of the chip, which not only protects the GaP layer with higher conductivity and reduces the overall voltage of the chip, but also can perform specular reflection to improve the light extraction efficiency. The present invention solves the problem in the prior art that the overall voltage of the chip is low when improving the light extraction efficiency of the chip.

[0054] Embodiment 2

[0055] Please refer to Figure 2 , which is the red-yellow GaAs-based LED chip provided in the second embodiment of the present invention. This chip is prepared by using the red-yellow GaAs-based LED chip in the first embodiment.

[0056] As Figure 2 shown, this LED chip includes a GaAs substrate 1, an epitaxial layer 2, a first carbon-doped GaP layer 3, a second carbon-doped GaP layer 4, a CB layer 5, and a mirror metal layer 6 that are sequentially stacked.

[0057] Among them, the epitaxial layer includes an N layer 21, a quantum well layer 22, and a P layer 23 grown in sequence. The N layer 21 is disposed on the side close to the substrate, and the P layer 23 is disposed on the side close to the first carbon-doped GaP layer. Part of the second carbon-doped GaP layer 4 close to the CB layer 5 incorporates Be ions, and CB holes 50 are etched on the CB layer 5.

[0058] In summary, for the red-yellow GaAs-based LED chip in the embodiment of the present invention, by providing the first carbon-doped GaP layer 3 and the second carbon-doped GaP layer 4, and then evaporating AuBe in the second carbon-doped GaP layer 4, the Be ions in the AuBe are diffused and incorporated into the second carbon-doped GaP layer 4 through an annealing process, so that the conductivity of the GaP layer is increased. Moreover, the barrier of the highly doped epitaxial structure is extremely thin, and electrons can directly penetrate the barrier to achieve an ohmic contact effect. The grown CB layer 5 and the mirror metal layer 6 on the CB layer 5 form a reflection structure to realize the reflection of the light of the chip, which not only protects the GaP layer with a higher conductivity and reduces the overall voltage of the chip, but also can perform specular reflection to improve the light extraction efficiency. The present invention solves the problem in the prior art that the overall voltage of the chip is low when improving the light extraction efficiency of the chip.

[0059] The above embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A method for preparing a red-yellow GaAs-based LED chip, characterized in that, the method comprises: providing a GaAs substrate; growing an epitaxial layer on the GaAs substrate; successively growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer, and evaporating AuBe on the second carbon-doped GaP layer; annealing to diffuse Be ions in the AuBe into the second carbon-doped GaP layer, and then etching the evaporated AuBe to expose the second carbon-doped GaP layer; growing a CB layer on the second carbon-doped GaP layer, and providing a mirror metal layer on the CB layer; in the step of annealing to diffuse Be ions in the AuBe into the second carbon-doped GaP layer, and then etching the evaporated AuBe to expose the second carbon-doped GaP layer, the proportion of the Be ions is 15% - 20%; the step of successively growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer, and evaporating AuBe on the second carbon-doped GaP layer comprises: growing a first carbon-doped GaP layer with a set doping concentration on the epitaxial layer, then transitioning to a transition GaP layer with a set concentration in steps of each preset doping concentration, and then continuing to grow a second carbon-doped GaP layer with a set doping concentration, and evaporating AuBe on the second carbon-doped GaP layer.

2. The method for preparing a red-yellow GaAs-based LED chip according to claim 1, characterized in that, The set doping concentration of the first carbon-doped GaP layer is 3e16 cm -3 , the set concentration of the second carbon-doped GaP layer is 3e17 cm -3 , the set concentration of the transition GaP layer is 3e17 cm -3 , the preset doping concentration is 3e1 cm -3 .

3. The method for preparing a red-yellow GaAs-based LED chip according to claim 1, characterized in that, in the step of annealing to diffuse Be ions in the AuBe into the second carbon-doped GaP layer, and then etching the evaporated AuBe to expose the second carbon-doped GaP layer, the AuBe is etched with a gold etchant.

4. The method for preparing a red-yellow GaAs-based LED chip according to claim 1, characterized in that, the step of growing a CB layer on the second carbon-doped GaP layer, and providing a mirror metal layer on the CB layer comprises: SiO is grown on the second carbon-doped GaP layer 2 as the CB layer, a CB pattern is lithographed on the CB layer, then a CB hole is wet-etched, and then mirror metal evaporation is performed on the CB layer to obtain a mirror metal layer.

5. The method for preparing a red-yellow GaAs-based LED chip according to claim 1, characterized in that, in the step of successively growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer, and evaporating AuBe on the second carbon-doped GaP layer, the growth thicknesses of the first carbon-doped GaP layer and the second carbon-doped GaP layer are the same.

6. The method for preparing a red-yellow GaAs-based LED chip according to claim 1 or 5, characterized in that, the growth thicknesses of both the first carbon-doped GaP layer and the second carbon-doped GaP layer are 5000 Å.

7. The method for preparing a red-yellow GaAs-based LED chip according to claim 1, characterized in that, in the step of successively growing a first carbon-doped GaP layer and a second carbon-doped GaP layer on the epitaxial layer, and evaporating AuBe on the second carbon-doped GaP layer, the evaporation thickness of the AuBe is 4000 Å.

8. A red-yellow GaAs-based LED chip, characterized in that, Prepared by using the preparation method described in any one of claims 1 to 7.

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