A red-yellow GaAs LED chip and its preparation method

Abstract

The present invention provides a red-yellow GaAs LED chip and a preparation method thereof, which relates to the field of chip technology. The chip comprises: a GaAs substrate; an epitaxial layer, which is arranged on one side surface of the GaAs substrate; a highly doped GaP layer, which comprises a first GaP layer, a second GaP layer, and a plurality of transition GaP layers sequentially arranged between the first GaP layer and the second GaP layer, wherein the first GaP layer is arranged on a side surface of the epitaxial layer away from the GaAs substrate, and the second GaP layer is arranged on a side surface of the transition GaP layer away from the first GaP layer, and be ions are injected into the second GaP layer; an ODR total reflection layer, which comprises a reflection medium layer and a mirror metal layer, and the reflection medium layer and the mirror metal layer are sequentially arranged on a side surface of the second GaP layer away from the first GaP layer. The present invention can solve the technical problem that SiO2 as a dielectric layer is not conductive in the prior art, and although a CB hole is etched as an ohmic contact channel, the overall voltage of the chip will still increase.

Description

Technical Field

[0001] The invention relates to the technical field of chips, and in particular to a red-yellow GaAs series LED chip and a preparation method thereof. Background Art

[0002] LED mirror is an extremely important process in the red-yellow GaAs LED forward-mounted reverse polarity vertical structure products, which can achieve the purpose of improving brightness. When the red-yellow GaAs LED chip MQW (quantum well) emits light, it is mainly used for forward light. However, due to the high light absorption characteristics of GaAs material, the light emitted from the bottom will be absorbed by GaAs and cannot be reflected back to the front. Therefore, the light emitted by GaAs chips without mirror layer is mainly forward light.

[0003] In order to improve light extraction efficiency and reduce light absorption, red and yellow GaAs products have produced unique forward-mounted reverse polarity products. The main feature is that a set of mirror structures are added below the epitaxy by replacing different substrates, so that when the MQW (quantum well) emits light, the light below can be reflected back to the forward direction by the mirror structure, thereby achieving the effect of increasing brightness. At present, the common mirror structure of red and yellow GaAs LEDs is mainly SiO2 as the dielectric layer, Au or Ag as the mirror metal layer, and ODR reflection is achieved through the dielectric layer and the mirror metal layer.

[0004] At present, the epitaxial growth of red and yellow GaAs LED chips replaces the substrate to add mirrors and dielectric layers to form an ODR structure. SiO2 as the dielectric layer is not conductive. Although CB holes are etched out as ohmic contact channels, the overall voltage of the chip will still increase. Summary of the invention

[0005] Based on this, the purpose of the present invention is to provide a red-yellow GaAs LED chip and a preparation method thereof, aiming to solve the technical problem in the prior art that the red-yellow GaAs LED chip is epitaxially replaced with a substrate to add a mirror and a dielectric layer to form an ODR structure, and SiO2 as a dielectric layer is not conductive. Although a CB hole is etched out as an ohmic contact channel, the overall voltage of the chip will still increase.

[0006] One aspect of the present invention is to provide a red-yellow GaAs LED chip, the LED chip comprising:

[0007] GaAs substrate;

[0008] An epitaxial layer is provided on one side surface of the GaAs substrate;

[0009] A highly doped GaP layer, comprising a first GaP layer, a second GaP layer, and a plurality of transition GaP layers sequentially arranged between the first GaP layer and the second GaP layer, wherein the first GaP layer is arranged on a surface of the epitaxial layer away from the GaAs substrate, the second GaP layer is arranged on a surface of the transition GaP layer away from the first GaP layer, and be ions are implanted into the second GaP layer;

[0010] The ODR total reflection layer comprises a reflection medium layer and a mirror metal layer, wherein the reflection medium layer and the mirror metal layer are sequentially arranged on a surface of the second GaP layer away from the first GaP layer.

[0011] According to one aspect of the above technical solution, the growth thickness of the first GaP layer is equal to the growth thickness of the second GaP layer.

[0012] According to one aspect of the above technical solution, the growth thickness of the first GaP layer and the growth thickness of the second GaP layer are both 5000Å.

[0013] According to one aspect of the above technical solution, the carbon doping concentration of the first GaP layer is 3e 16 cm -3 , the carbon doping concentration of the second GaP layer is 3e 17 cm -3 .

[0014] According to one aspect of the above technical solution, the carbon doping solubility of the plurality of transition GaP layers disposed between the first GaP layer and the second GaP layer gradually increases from the first GaP layer side to the second GaP layer side.

[0015] According to one aspect of the above technical solution, the carbon doping solubility of the multiple transition GaP layers gradually transitions from the first GaP layer side to the second GaP layer side with a step of every 3e1cm-3, and the growth thickness of each transition GaP layer is 1000 Å.

[0016] According to one aspect of the above technical solution, the second GaP layer is a patterned GaP layer.

[0017] According to one aspect of the above technical solution, SiO2 is grown or MgF2 is evaporated on the surface of the second GaP layer away from the transition GaP layer to form the reflective medium layer;

[0018] ITO+Ag or ITO+Au or Au or Al is evaporated on the surface of the reflective medium layer on one side away from the second GaP layer to form the mirror metal layer.

[0019] Another aspect of the present invention is to provide a method for preparing a red-yellow GaAs LED chip, the method being used to prepare the red-yellow GaAs LED chip described in the above technical solution, the method comprising:

[0020] Providing a GaAs substrate;

[0021] Growing an epitaxial layer on one side surface of the GaAs substrate;

[0022] A highly doped GaP layer is grown on a surface of one side of the epitaxial layer, wherein the highly doped GaP layer includes a first GaP layer, a second GaP layer, and a plurality of transition GaP layers sequentially arranged between the first GaP layer and the second GaP layer, wherein the doping solubility of the plurality of transition GaP layers gradually increases from the first GaP layer side to the second GaP layer side, and Be ions are implanted into the second GaP layer;

[0023] An ODR total reflection layer is fabricated on the second GaP layer. The ODR total reflection layer comprises a reflection medium layer and a mirror metal layer. The reflection medium layer and the mirror metal layer are sequentially arranged on a surface of the second GaP layer away from the first GaP layer.

[0024] According to one aspect of the above technical solution, in the method:

[0025] The step of implanting Be ions into the second GaP layer is specifically as follows:

[0026] implanting Be ions into the second GaP layer by an ion implanter;

[0027] After the step of implanting Be ions into the second GaP layer by an ion implanter, the method further comprises:

[0028] A patterned second GaP layer doped with Be ions is produced by photolithography and wet etching.

[0029] Compared with the prior art, the red-yellow GaAs LED chip and its preparation method shown in this embodiment have the following beneficial effects: by using ion implantation to inject Be ions into the high-doped GaP layer, the electron content in the high-doped GaP layer is extremely high, the conductivity of the epitaxial wafer is improved, and the high-doped epitaxial structure makes the barrier extremely thin, and with the low-temperature mirror that does not require annealing, the electrons can directly penetrate the barrier to achieve the ohmic contact effect, which is beneficial to reduce the chip voltage; and a new type of reflective medium layer is obtained by combining the patterned high-doped GaP layer with SiO2 or MgF2, which replaces the original SiO2 layer and can cooperate with the mirror metal layer to form ODR total reflection. Therefore, the red-yellow GaAs LED chip provided by the invention can not only effectively improve the luminous brightness of the red-yellow GaAs LED chip, but also improve the conductivity and reduce the chip voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of a red-yellow GaAs LED chip in the first embodiment of the present invention;

[0031] Figure 2 It is a schematic diagram of the process of preparing a red-yellow GaAs LED chip in the second embodiment of the present invention;

[0032] The following specific implementations will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0034] Embodiment 1

[0035] See also Figure 1 The first embodiment of the present invention provides a red-yellow GaAs LED chip, which includes a GaAs substrate 10, an epitaxial layer 20, a highly doped GaP layer 30 and an ODR total reflection layer.

[0036] Among them, GaAs substrate 10 is a new type of semiconductor material that has been studied most deeply and applied most widely after Si substrate 10. It has the characteristics of high mobility, large bandgap, high temperature resistance, etc. It is mainly used in high-frequency communication, wireless network and optoelectronic fields, such as LED light emitters, solar panels, etc. Among them, the epitaxial layer 20 is arranged on one side surface of the GaAs substrate 10, including N layer 21, MQW 22 and P layer 23.

[0037] The highly doped GaP layer 30 includes a first GaP layer 31, a second GaP layer 32, and a plurality of transition GaP layers sequentially arranged between the first GaP layer 31 and the second GaP layer 32, wherein the first GaP layer 31 is arranged on a side surface of the epitaxial layer 20 away from the GaAs substrate 10, the second GaP layer 32 is arranged on a side surface of the transition GaP layer away from the first GaP layer 31, and be ions 320 are implanted into the second GaP layer 32;

[0038] Specifically, a plurality of transition GaP layers are provided between the first GaP layer 31 and the second GaP layer 32. In this embodiment, the growth thickness of the first GaP layer 31 is equal to the growth thickness of the second GaP layer 32, and the growth thickness of the first GaP layer 31 and the growth thickness of the second GaP layer 32 are both 5000Å. The carbon doping concentration of the first GaP layer 31 is 3e 16 cm -3 The carbon doping concentration of the second GaP layer 32 is 3e 17 cm -3 .

[0039] By way of example and not limitation, the carbon doping concentration of the plurality of transition GaP layers disposed between the first GaP layer 31 and the second GaP layer 32 gradually increases from the first GaP layer 31 side to the second GaP layer 32 side. Specifically, the carbon doping concentration of the plurality of transition GaP layers increases from the first GaP layer 31 side to the second GaP layer 32 side by 3e / cm3. 1 cm -3 A step transition is formed, and the growth thickness of each transition GaP layer is 1000Å.

[0040] In addition, the second GaP layer 32 is a patterned GaP layer. By injecting Be ions 320 into the highly doped, patterned second GaP layer 32, the electron content in the highly doped GaP layer 30 (including the first GaP layer 31, the second GaP layer 32 and the transition GaP layer) is extremely high, and the highly doped epitaxial structure makes the potential barrier extremely thin. Combined with the low-temperature mirror that does not require annealing, electrons can directly penetrate the potential barrier to achieve an ohmic contact effect, which will be very beneficial to reducing the chip voltage.

[0041] The ODR total reflection layer includes a reflective medium layer 34 and a mirror metal layer 40, which are sequentially arranged on a surface of the second GaP layer 32 away from the first GaP layer 31. Specifically, the reflective medium layer 34 obtained by combining SiO2 or MgF2 with the patterned high-doped GaP layer 30 replaces the original SiO2 layer and forms an ODR total reflection with the mirror metal layer 40.

[0042] By way of example but not limitation, SiO2 is grown on the surface of the second GaP layer 32 on a side away from the transition GaP layer to form the reflective medium layer 34; and ITO+Ag is evaporated on the surface of the reflective medium layer 34 on a side away from the second GaP layer 32 to form the mirror metal layer 40. Specifically, the reflective medium layer 34 and the mirror metal layer 40 can cooperate to achieve a high reflectivity, and are not limited to the reflective medium material and the mirror metal material provided in this embodiment.

[0043] In some feasible embodiments, MgF2 is evaporated on a surface of the second GaP layer 32 away from the transition GaP layer to form the reflective medium layer 34 ; and ITO+Au is evaporated on a surface of the reflective medium layer 34 away from the second GaP layer 32 to form the mirror metal layer 40 .

[0044] Compared with the prior art, the red-yellow GaAs LED chip shown in this embodiment has the following beneficial effects: by using ion implantation to inject Be ions into the highly doped GaP layer, the electron content in the highly doped GaP layer 30 is extremely high, thereby improving the conductivity of the epitaxial wafer, and the highly doped epitaxial structure makes the potential barrier extremely thin, and with the low-temperature mirror that does not require annealing, electrons can directly penetrate the potential barrier to achieve an ohmic contact effect, thereby helping to reduce the chip voltage; and a new type of reflective medium layer 34 is obtained by patterning the highly doped GaP layer 30 in combination with SiO2 or MgF2, and the reflective medium layer 34 replaces the original SiO2 layer and can cooperate with the mirror metal layer 40 to form ODR total reflection.

[0045] Therefore, the red-yellow GaAs LED chip shown in this embodiment can not only effectively improve the luminous brightness of the red-yellow GaAs LED chip, but also improve the conductivity and reduce the chip voltage.

[0046] Embodiment 2

[0047] See also Figure 2 The second embodiment of the present invention provides a method for preparing a red-yellow GaAs LED chip, which is used to prepare the red-yellow GaAs LED chip described in the first embodiment. The method comprises steps S10-S40:

[0048] Step S10, providing a GaAs substrate;

[0049] Step S20, growing an epitaxial layer on one side surface of the GaAs substrate;

[0050] Step S30, growing a highly doped GaP layer on a surface of one side of the epitaxial layer, the highly doped GaP layer comprising a first GaP layer, a second GaP layer, and a plurality of transition GaP layers sequentially disposed between the first GaP layer and the second GaP layer, the doping solubility of the plurality of transition GaP layers gradually increasing from the first GaP layer side to the second GaP layer side, and implanting Be ions into the second GaP layer;

[0051] Step S40, manufacturing an ODR total reflection layer on the second GaP layer, wherein the ODR total reflection layer comprises a reflection medium layer and a mirror metal layer, wherein the reflection medium layer and the mirror metal layer are sequentially disposed on a surface of the second GaP layer away from the first GaP layer.

[0052] Specifically, the method for preparing the red-yellow GaAs LED chip shown in this embodiment includes:

[0053] Growing GaAs as a buffer layer on a GaAs substrate layer;

[0054] Growing GaInP on the buffer layer as a cutoff layer;

[0055] Growing GaAs on the cutoff layer as an N-contact layer;

[0056] Growing GaInP on the N-contact layer as an N-transition layer;

[0057] Growing AlxGaInP on the N-transition layer as an N-current spreading layer;

[0058] N-AlInP is grown on the N-current spreading layer to provide electrons;

[0059] Growing AlGaInP as an N-barrier layer on the N-AlInP layer;

[0060] Growing an MQW quantum well on the N-barrier layer as a light-emitting layer;

[0061] AlGaInP is grown on the MQW quantum well as a P-barrier layer;

[0062] Growing P-AlInP on the P-barrier layer to provide holes;

[0063] Growing AlGaInP on P-AlInP as a transition layer;

[0064] Growth of 5000Å carbon-doped 3e on the transition layer 16 cm -3 The first GaP layer is then grown in steps of 3e1 to 3e 17 cm -3A 1000Å transition GaP layer was then grown followed by a 5000Å carbon-doped 3e 17 cm -3 A second GaP layer;

[0065] Be ions are implanted into the second GaP layer using an ion implanter, and then a patterned highly doped GaP layer doped with Be ions is manufactured by photolithography and wet etching;

[0066] SiO2 is grown or MgF2 is evaporated on the epitaxial wafer of the patterned highly doped GaP layer to fill the depressions of the patterned GaP layer. This structure is used as a reflective medium layer, and ITO+Ag or ITO+Au or Au or Al is evaporated on the reflective medium layer as a mirror metal layer.

[0067] Specifically, the step of injecting Be ions into the second GaP layer is as follows:

[0068] implanting Be ions into the second GaP layer by an ion implanter;

[0069] After the step of implanting Be ions into the second GaP layer by an ion implanter, the method further comprises:

[0070] A patterned second GaP layer doped with Be ions is produced by photolithography and wet etching.

[0071] Compared with the prior art, the method for preparing the red-yellow GaAs LED chip shown in this embodiment has the following beneficial effects: by using ion implantation to inject Be ions into the highly doped GaP layer, the electron content in the highly doped GaP layer is extremely high, the conductivity of the epitaxial wafer is improved, and the highly doped epitaxial structure makes the potential barrier extremely thin, and with the low-temperature mirror that does not require annealing, electrons can directly penetrate the potential barrier to achieve an ohmic contact effect, which is beneficial to reducing the chip voltage; and a new type of reflective medium layer is obtained by patterning the highly doped GaP layer in combination with SiO2 or MgF2, which replaces the original SiO2 layer and can cooperate with the mirror metal layer to form ODR total reflection.

[0072] Therefore, the red-yellow GaAs LED chip obtained by the preparation method of the red-yellow GaAs LED chip shown in this embodiment can not only effectively improve the luminous brightness of the red-yellow GaAs LED chip, but also improve the conductivity and reduce the chip voltage.

[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0074] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which 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 attached claims.

Claims

1. A red-yellow GaAs LED chip, characterized in that: The LED chip comprises: GaAs substrate; An epitaxial layer is provided on one side surface of the GaAs substrate; A highly doped GaP layer, comprising a first GaP layer, a second GaP layer, and a plurality of transition GaP layers sequentially arranged between the first GaP layer and the second GaP layer, wherein the first GaP layer is arranged on a surface of the epitaxial layer away from the GaAs substrate, the second GaP layer is arranged on a surface of the transition GaP layer away from the first GaP layer, and be ions are implanted into the second GaP layer; The ODR total reflection layer comprises a reflection medium layer and a mirror metal layer, wherein the reflection medium layer and the mirror metal layer are sequentially arranged on a surface of the second GaP layer away from the first GaP layer; The first GaP layer, the transition GaP layer and the second GaP layer are all doped with carbon, and the carbon doping concentration of the first GaP layer is 3e 16 cm -3 , the carbon doping concentration of the second GaP layer is 3e 17 cm -3 The carbon doping concentration of the transition GaP layers increases from the first GaP layer side to the second GaP layer side by 3e 1 cm -3 A step transition is formed, and the growth thickness of each transition GaP layer is 1000Å.

2. The red-yellow GaAs LED chip according to claim 1, characterized in that: The growth thickness of the first GaP layer is equal to the growth thickness of the second GaP layer.

3. The red-yellow GaAs LED chip according to claim 2, characterized in that: The growth thickness of the first GaP layer and the growth thickness of the second GaP layer are both 5000Å.

4. The red-yellow GaAs LED chip according to claim 1, characterized in that: The second GaP layer is a patterned GaP layer.

5. The red-yellow GaAs LED chip according to claim 4, characterized in that: SiO2 is grown or MgF2 is evaporated on the surface of the second GaP layer away from the transition GaP layer to form the reflective medium layer; ITO+Ag or ITO+Au or Au or Al is evaporated on the surface of the reflective medium layer on one side away from the second GaP layer to form the mirror metal layer.

6. A method for preparing a red-yellow GaAs LED chip, characterized in that: The preparation method is used to prepare the red-yellow GaAs LED chip according to any one of claims 1 to 5, and the preparation method comprises: Providing a GaAs substrate; Growing an epitaxial layer on one side surface of the GaAs substrate; A highly doped GaP layer is grown on a surface of one side of the epitaxial layer, wherein the highly doped GaP layer includes a first GaP layer, a second GaP layer, and a plurality of transition GaP layers sequentially arranged between the first GaP layer and the second GaP layer, wherein the doping solubility of the plurality of transition GaP layers gradually increases from the first GaP layer side to the second GaP layer side, and Be ions are implanted into the second GaP layer; An ODR total reflection layer is fabricated on the second GaP layer. The ODR total reflection layer comprises a reflection medium layer and a mirror metal layer. The reflection medium layer and the mirror metal layer are sequentially arranged on a surface of the second GaP layer away from the first GaP layer.

7. The method for preparing a red-yellow GaAs LED chip according to claim 6, characterized in that: In the method: The step of implanting Be ions into the second GaP layer is specifically as follows: implanting Be ions into the second GaP layer by an ion implanter; After the step of implanting Be ions into the second GaP layer by an ion implanter, the method further comprises: A patterned second GaP layer doped with Be ions is produced by photolithography and wet etching.

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