Vertical cavity surface emitting laser and method for manufacturing the same

Abstract

The application discloses a vertical cavity surface emitting laser and a preparation method thereof. The method comprises the following steps: sequentially forming a first epitaxial layer, a sacrificial layer, a second epitaxial layer and a first DBR reflecting layer on a first substrate, wherein the second epitaxial layer comprises at least an active layer; performing a patterning treatment on the first DBR reflecting layer, the second epitaxial layer and the sacrificial layer; adopting an electrochemical etching method to etch away the patterned sacrificial layer, so as to separate the patterned second epitaxial layer and the patterned first DBR reflecting layer from the first epitaxial layer as a whole; bonding the separated patterned first DBR reflecting layer and the patterned second epitaxial layer with a second substrate; and forming a patterned second DBR reflecting layer on a side of the patterned second epitaxial layer, which is away from the patterned first DBR reflecting layer, so as to obtain the VCSEL. By setting the sacrificial layer and cooperating with the electrochemical etching, the smoothness of the surface of the separated epitaxial layer can be improved, so that the light-emitting efficiency and stability of the VCSEL are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor lasers, and particularly relates to a vertical-cavity surface-emitting laser and a preparation method thereof. BACKGROUND

[0002] A vertical-cavity surface-emitting laser (VCSEL) is a new type of semiconductor laser, which generally comprises a bottom DBR (distributed Bragg reflector), an active layer and a top DBR. The DBRs form a resonant cavity on both sides of the active layer, and the higher the reflectivity of the DBR, the more times the laser is reflected in the resonant cavity, and the stronger the intensity of the laser. Therefore, the reflectivity of the DBR has an important influence on the performance of the VCSEL.

[0003] The existing method for preparing the VCSEL generally comprises: forming an epitaxial layer and a first DBR layer on a first substrate; using a laser lift-off (LLO) technology to separate the epitaxial layer and the first DBR layer from the substrate; bonding the separated first DBR layer and epitaxial layer with a second substrate; and forming a second DBR layer on a side of the epitaxial layer away from the first DBR layer. At this time, the first DBR layer and the second DBR layer are respectively located on the upper and lower sides of the active layer, and the laser is reflected back into the resonant cavity, thereby realizing the amplification and oscillation of the laser.

[0004] However, in the laser lift-off process, the thermal shock caused by laser irradiation is easy to cause the film layer (such as an AlGaN film) in the epitaxial structure to crack, and the thermal decomposition of AlGaN will produce hard aluminum residues, which will increase the surface roughness and further increase the scattering loss of the VCSEL.

[0005] Therefore, how to prepare a DBR structure with high reflectivity under the premise of ensuring the performance of the VCSEL device, so as to improve the light-emitting efficiency and stability of the VCSEL is a technical problem to be solved at present. SUMMARY

[0006] In view of the above problems, the present application is proposed to provide a vertical-cavity surface-emitting laser and a preparation method thereof, which overcomes the above problems or at least partially solves the above problems. By using a method of a sacrifice layer combined with electrochemical etching, part of the epitaxial layer is separated, and the smoothness of the surface of the separated epitaxial layer is improved, which is conducive to the formation of a DBR structure with high reflectivity, thereby improving the light-emitting efficiency and stability of the VCSEL.

[0007] In a first aspect, a preparation method of a vertical-cavity surface-emitting laser is provided, and the preparation method comprises:

[0008] forming a first epitaxial layer, a sacrificial layer, a second epitaxial layer and a first DBR reflective layer on a first substrate in sequence, the second epitaxial layer comprising at least an active layer;

[0009] performing a patterning process on the first DBR reflective layer, the second epitaxial layer and the sacrificial layer to form at least one patterning structure on a side of the first epitaxial layer away from the first substrate, the patterning structure comprising a patterning sacrificial layer, a patterning second epitaxial layer and a patterning first DBR reflective layer;

[0010] adopting an electrochemical etching method to etch away the patterning sacrificial layer in the patterning structure to separate the patterning second epitaxial layer and the patterning first DBR reflective layer from the first epitaxial layer;

[0011] bonding the separated patterning first DBR reflective layer and the patterning second epitaxial layer with a second substrate, the patterning first DBR reflective layer being between the patterning second epitaxial layer and the second substrate;

[0012] forming a patterning second DBR reflective layer on a side of the patterning second epitaxial layer away from the patterning first DBR reflective layer to obtain the vertical cavity surface emitting laser.

[0013] In some implementations, the patterning first DBR reflective layer and the patterning second DBR reflective layer comprise a plurality of first reflective layers and a plurality of second reflective layers arranged in sequence and staggered, the first reflective layers and the second reflective layers being HfO2 layers and SiO2 layers respectively.

[0014] In some implementations, the bonding the separated patterning first DBR reflective layer and the patterning second epitaxial layer with a second substrate comprises:

[0015] picking up the separated patterning first DBR reflective layer and the patterning second epitaxial layer using an organic substrate, the patterning first DBR reflective layer being between the patterning second epitaxial layer and the organic substrate;

[0016] bonding a side of the organic substrate away from the patterning first DBR reflective layer and the patterning second epitaxial layer with the second substrate.

[0017] In some implementations, the adopting an electrochemical etching method to etch away the patterning sacrificial layer in the patterning structure comprises:

[0018] soldering an electrical contact material on an edge of the first epitaxial layer, and electrically connecting the first epitaxial layer to a positive pole of a power source through the electrical contact material, a negative pole of the power source being electrically connected to a cathode material;

[0019] The first substrate formed with the first epitaxial layer and the patterned structure is put into an electrolyte, the first epitaxial layer is used as an anode, the cathode material is used as a cathode, and the patterned sacrificial layer in the patterned structure is electrochemically etched.

[0020] In some implementations, the electrical contact material is indium, and the cathode material is platinum.

[0021] In some implementations, the patterning the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer includes:

[0022] forming a patterned photoresist layer on the first DBR reflective layer;

[0023] etching away the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer at the opening positions of the photoresist layer to transfer the pattern on the photoresist layer to the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer, forming the patterned first DBR reflective layer, the patterned second epitaxial layer, and the patterned sacrificial layer;

[0024] removing the patterned photoresist layer.

[0025] In some implementations, the sacrificial layer is an N-type doped AlGaN layer or an N-type doped GaN layer.

[0026] In some implementations, the first substrate and the second substrate are both sapphire substrates, the first epitaxial layer includes a nucleation layer, a buffer layer, and a current spreading layer sequentially stacked on the first substrate, and the active layer includes a plurality of quantum well layers and a plurality of quantum barrier layers alternately arranged.

[0027] wherein a material of the nucleation layer includes AlN, a material of the buffer layer includes Al a Ga (1-a) N, a material of the current spreading layer includes Al b Ga (1-b) N, a material of the quantum well layer includes Al k1 Ga (1-k1) N, a material of the quantum barrier layer includes Al k2 Ga (1-k2) N, a > 0.5, b > 0.5, k1 > 0.5, and k2 > 0.5.

[0028] In some implementations, the second epitaxial layer further includes a first resonant cavity adjustment layer and a second resonant cavity adjustment layer, the first resonant cavity adjustment layer is located between the active layer and the sacrificial layer, and the second resonant cavity adjustment layer is located on a side of the active layer away from the sacrificial layer.

[0029] The first resonant cavity adjusting layer is an AlcGa(1-c)N layer, and the second resonant cavity adjusting layer is an AldGa(1-d)N layer, c>0.5, and d>0.5.

[0030] The technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0031] The vertical cavity surface emitting laser and the preparation method thereof provided by the embodiment of the present application, by forming a sacrifice layer in the epitaxial layer growth process, the epitaxial layer is grown in two parts, then the first DBR reflection layer, the second epitaxial layer including the active layer and the sacrifice layer are patterned, at least one patterned structure is formed on the side of the first epitaxial layer away from the first substrate, at this time, since the sacrifice layer is patterned, part of the sacrifice layer is exposed, which is convenient for subsequent electrochemical etching method to etch away the sacrifice layer, so as to separate the patterned second epitaxial layer and the patterned first DBR reflection layer from the first epitaxial layer; then, the separated patterned first DBR reflection layer and the patterned second epitaxial layer are bonded with the second substrate, and the patterned first DBR reflection layer is located between the patterned second epitaxial layer and the second substrate, at this time, the first DBR reflection layer is located at the bottom of the active layer, that is, as the bottom DBR layer. Finally, the patterned second DBR reflection layer is formed on the side of the patterned second epitaxial layer away from the patterned first DBR reflection layer, as the top DBR layer, and the required vertical cavity surface emitting laser is prepared. The present application adopts the method of sacrifice layer combined with electrochemical etching, compared with the traditional laser separation method, the electrochemical etching method has higher precision and controllability, can reduce the thermal shock and mechanical damage to the epitaxial layer, makes the surface of the separated second epitaxial layer smoother, and by accurately controlling the electrochemical etching process, the cracking of each film layer in the second epitaxial layer and the generation of aluminum residues can be reduced, thereby reducing the scattering loss of the VCSEL, improving the reliability and stability of the device, and at the same time, the preparation cost of the VCSEL can be reduced, and the production efficiency can be improved.

[0032] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application, the specific embodiments of the present application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0033] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of illustrating the preferred embodiments and are not considered limiting on the present application. Moreover, the same reference symbols are used throughout the drawings to represent the same parts. In the drawings:

[0034] Figure 1 is a preparation method flowchart of a vertical cavity surface emitting laser provided by an embodiment of the present application;

[0035] Figure 2 is an epitaxial structure schematic diagram provided by an embodiment of the present application;

[0036] Figure 3 is a structure schematic diagram after step S110 is executed;

[0037] Figure 4 is a structure schematic diagram after step S121 is executed;

[0038] Figure 5 is a structure schematic diagram after step S122 is executed;

[0039] Figure 6 is a top view of the structure shown in Figure 5

[0040] Figure 7 is a structure schematic diagram of electrochemical etching provided by an embodiment of the present application;

[0041] Figure 8 is a structure schematic diagram when step S141 is executed;

[0042] Figure 9 is a structure schematic diagram after step S142 is executed;

[0043] Figure 10 is a structure schematic diagram after step S150 is executed;

[0044] Figure 11 is a schematic diagram of the relationship between the emission intensity and the pump power density of a VCSEL prepared by the preparation method provided by the present application;

[0045] Figure 12 is a schematic diagram of the emission spectrum of a VCSEL prepared by the preparation method provided by the present application under different excitation levels. DETAILED DESCRIPTION

[0046] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in combination with the drawings of the specification and specific embodiments. It should be understood that the embodiments of the present disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, and not limitations of the technical solutions of the present application. In the case of no conflict, the technical features in the embodiments of the present application and the embodiments can be combined with each other.

[0047] Figure 1 is a preparation method flowchart of a vertical cavity surface emitting laser provided by an embodiment of the present application, as Figure 1 ​As shown, the preparation method comprises:

[0048] The step S110 comprises sequentially forming a first epitaxial layer, a sacrificial layer, a second epitaxial layer and a first DBR reflection layer on the first substrate, and the second epitaxial layer at least comprises an active layer.

[0049] In some implementations, the first substrate is a sapphire substrate, the first epitaxial layer comprises a nucleation layer, a buffer layer and a current spreading layer which are sequentially arranged on the first substrate, and the active layer comprises a plurality of quantum well layers and a plurality of quantum barrier layers which are alternately arranged. The material of the nucleation layer comprises AlN, the material of the buffer layer comprises Al a Ga (1-a) N, the material of the current spreading layer comprises Al b Ga (1-b) N, the material of the quantum well layer comprises Al k1 Ga (1-k1) N, the material of the quantum barrier layer comprises Al k2 Ga (1-k2) N, a>0.5, b>0.5, k1>0.5, k2>0.5.

[0050] The nucleation layer is an AlN layer, and AlN has a small lattice mismatch and a small coefficient of thermal expansion mismatch with the subsequent epitaxial layer (such as AlGaN), which helps to reduce stress accumulation during epitaxial growth, reduce defect density, and thus improve the crystal quality and structural integrity of the epitaxial layer. During epitaxial growth, the buffer layer can adjust and relieve the stress caused by lattice mismatch, etc., to ensure the flatness of the epitaxial structure and reduce defects, and the current spreading layer is used to enhance the lateral spreading of current within the chip, so that the current can be more uniformly distributed in the entire active area, thereby improving the light extraction efficiency and electrical performance of the device.

[0051] In some implementations, the second epitaxial layer further comprises a first resonant cavity adjusting layer and a second resonant cavity adjusting layer, the first resonant cavity adjusting layer is located between the active layer and the sacrificial layer, and the second resonant cavity adjusting layer is located on the side of the active layer away from the sacrificial layer. The first resonant cavity adjusting layer is an Al c Ga (1-c) N layer, and the second resonant cavity adjusting layer is an Al d Ga (1-d) N layer, c>0.5, d>0.5. The first resonant cavity adjusting layer and the second resonant cavity adjusting layer together with the active layer form a resonant cavity, and the first resonant cavity adjusting layer and the second resonant cavity adjusting layer can adjust the length of the resonant cavity.

[0052] It should be noted that the VCSEL in the above implementations is an AlGaN-based deep ultraviolet VCSEL, and the content of Al in each AlGaN is greater than 0.5 to prevent each AlGaN layer from absorbing light.

[0053] In some implementations, the first DBR reflective layer includes a plurality of first reflective layers and a plurality of second reflective layers arranged alternately in sequence, and the first reflective layers and the second reflective layers are HfO2 layers and SiO2 layers respectively. Both HfO2 and SiO2 are chemically stable materials, which are not easy to chemically react with other substances, thereby ensuring the long-term stability and reliability of the DBR structure. In addition, there is usually good etching selectivity between HfO2 and SiO2, which helps to accurately remove or pattern specific layers in subsequent process steps without damaging other structure layers. The thin film deposition technology of HfO2 and SiO2 is relatively mature, which can be prepared by sputtering, chemical vapor deposition and other methods, and the process control is relatively simple.

[0054] In some implementations, the sacrificial layer is an N-type doped AlGaN layer or an N-type doped GaN layer. The N-type doped AlGaN and GaN layer has a large number of free electrons inside, which can participate in the anodic oxidation reaction in the electrochemical etching process, thereby accelerating the etching process. In addition, the n-type AlGaN and GaN layer has good electrical conductivity, which is conducive to the transmission of current and the progress of etching reaction. At the same time, the AlGaN or GaN layer can better match other epitaxial layers, reduce lattice mismatch and stress, and ensure the crystal quality of the second epitaxial layer grown thereon.

[0055] In some implementations, a metal organic chemical vapor deposition (MOCVD) method can be used to form the first epitaxial layer, the sacrificial layer and the second epitaxial layer on the first substrate.

[0056] Figure 2 is a schematic diagram of an epitaxial structure provided by an embodiment of the present application, as shown in Figure 2 The epitaxial structure includes a first epitaxial layer 20, a sacrificial layer 30 and a second epitaxial layer 40 arranged in sequence on a first substrate 10. The first epitaxial layer 20 includes a nucleation layer 21, a buffer layer 22 and a current spreading layer 23 arranged in sequence, and the second epitaxial layer 40 includes a first resonant cavity adjusting layer 41, an active layer 42 and a second resonant cavity adjusting layer 43 arranged in sequence.

[0057] For example, the nucleation layer 221 is an AlN layer of 700 nm, the buffer layer is an Al 0.8 Ga 0.2 N layer of 200 nm, and the current spreading layer is an Al 0.6 Ga 0.4 N layer of 500 nm, the sacrificial layer is an N-type GaN layer of 20 nm, the first resonant cavity adjusting layer is an Al 0.5 Ga 0.5 N layer of 190 nm, and the second resonant cavity adjusting layer is an Al 0.5 Ga 0.5N layer, the active layer includes 5 periods of 2 nm Al 0.55 Ga 0.45 N quantum well layers and 9 nm Al 0.45 Ga 0.55 N quantum barrier layers. The first DBR reflective layer includes 15.5 pairs of HfO2 / SiO2 layers arranged in sequence.

[0058] Figure 3 is a structural schematic diagram after step S110 is performed. As shown in Figure 3 , the first epitaxial layer 20, the sacrificial layer 30, the second epitaxial layer 40, and the first DBR reflective layer 50 are sequentially stacked on the first substrate 10 at this time.

[0059] Step S120, the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer are patterned to form at least one patterned structure on the side of the first epitaxial layer away from the first substrate, and the patterned structure includes a patterned sacrificial layer, a patterned second epitaxial layer, and a patterned first DBR reflective layer.

[0060] In some implementations, step S120 includes:

[0061] Step S121, forming a patterned photoresist layer on the first DBR reflective layer.

[0062] For example, a desired patterned photoresist layer can be formed on the first DBR reflective layer by coating, exposing, developing, etc. This is a conventional technique and will not be described here.

[0063] Figure 4 is a structural schematic diagram after step S121 is performed. As shown in Figure 4 , the patterned photoresist layer 51 is formed on the first DBR reflective layer 50 at this time.

[0064] Step S122, etching away the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer at the opening position of the photoresist layer to transfer the pattern on the patterned photoresist to the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer, forming a patterned first DBR reflective layer, a patterned second epitaxial layer, and a patterned sacrificial layer.

[0065] As shown in Figure 4 , the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer at the opening position of the photoresist layer are the portions of the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer on the first substrate 10 whose orthographic projections are located in Figure 4 the opening region a. Figure 5 is a structural schematic diagram after step S122 is performed. As shown in Figure 5As shown, the first DBR reflective layer, the second epitaxial layer and the sacrificial layer located in the opening area a are etched to form the patterned first DBR reflective layer 50a, the patterned second epitaxial layer 40a and the patterned sacrificial layer 30a.

[0066] In some implementations, a buffer oxide etchant (BOE) solution is used to wet-etch the first DBR reflective layer at the opening position of the photoresist layer, and an inductively coupled plasma (ICP) is used to dry-etch the second epitaxial layer and the sacrificial layer at the opening position of the photoresist layer.

[0067] Step S123: removing the patterned photoresist layer.

[0068] Figure 6 is Figure 5 is a top view of the structure as shown in Figure 6 As shown, the side of the first epitaxial layer 20 away from the first substrate 10 forms at least one patterned structure A, each of which includes a patterned first DBR reflective layer 50a, a patterned second epitaxial layer 40a and a patterned sacrificial layer 30a as shown. Figure 5

[0069] In some implementations, the patterned first DBR reflective layer includes a plurality of first reflective layers and a plurality of second reflective layers arranged alternately, the first reflective layers and the second reflective layers being HfO2 layers and SiO2 layers respectively.

[0070] Step S130: using an electrochemical etching method to etch the patterned sacrificial layer in the patterned structure, so as to separate the patterned second epitaxial layer and the patterned first DBR reflective layer from the first epitaxial layer.

[0071] In some implementations, step S130 includes:

[0072] In some implementations, step S130 includes:

[0073] For example, when the electrochemical etching is performed, the working voltage provided by the power supply is 20V, the etching time is 30 minutes, and the electrolyte is nitric acid with a concentration of 1 mole per liter.

[0074] In some implementations, the electrical contact material is indium, and the cathode material is platinum.

[0075] Figure 7 is a schematic diagram of an electrochemical etching structure provided by an embodiment of the present application, as shown in​Figure 7 As shown, at this time, the first epitaxial layer 20 serves as an anode, and a cathode material 60 (platinum) serves as a cathode, and the patterned sacrificial layer in the patterned structure is electrochemically etched.

[0076] Step S140, bonding the patterned first DBR reflective layer and the patterned second epitaxial layer after peeling off with the second substrate, and the patterned first DBR reflective layer is between the patterned second epitaxial layer and the second substrate.

[0077] In some implementations, step S140 includes:

[0078] Step S141, picking up the patterned first DBR reflective layer and the patterned second epitaxial layer after peeling off using an organic substrate, and the patterned first DBR reflective layer is between the patterned second epitaxial layer and the organic substrate.

[0079] Exemplarily, the organic substrate can be polyimide, which can pick up the patterned first DBR reflective layer and the patterned second epitaxial layer after peeling off.

[0080] Figure 8 is a structural schematic diagram when step S141 is performed, as Figure 8 shown, Figure 8 S1 in Figure 8 represents the patterned first DBR reflective layer and the patterned second epitaxial layer after peeling off as a whole, at this time, the organic substrate 70 picks up the patterned first DBR reflective layer and the patterned second epitaxial layer (i.e. the S1 part in

[0081] Step S142, bonding the side of the organic substrate away from the patterned first DBR reflective layer and the patterned second epitaxial layer with the second substrate.

[0082] Figure 9 is a structural schematic diagram after step S142 is performed, as Figure 9 shown, at this time, the organic substrate 70 is bonded with the second substrate 80, and the patterned first DBR reflective layer and the patterned second epitaxial layer (i.e. the S1 part in Figure 9 ) are on the side of the organic substrate 70 away from the second substrate 80.

[0083] Step S150, forming a patterned second DBR reflective layer on the side of the patterned second epitaxial layer away from the patterned first DBR reflective layer to obtain a vertical cavity surface emitting laser.

[0084] In some implementations, the patterned second DBR reflective layer comprises a plurality of first reflective layers and a plurality of second reflective layers arranged alternately, the first reflective layers and the second reflective layers are HfO2 layers and SiO2 layers respectively.

[0085] In some implementations, the step S150 comprises:

[0086] forming a second reflective layer on the side of the patterned second epitaxial layer away from the patterned first DBR reflective layer; forming a patterned photoresist layer on the second reflective layer, the pattern on the patterned photoresist layer is the same as the pattern on the patterned second epitaxial layer; removing the second reflective layer at the position of the opening of the patterned photoresist layer by using a wet etching process to transfer the pattern on the photoresist layer to the second reflective layer to form a patterned second DBR reflective layer; and removing the patterned photoresist layer.

[0087] For example, the patterned photoresist layer on the first DBR reflective layer can be formed by using the methods of gluing, exposing, developing, etc. This is a conventional technology and will not be described here in detail.

[0088] In some implementations, the step S150 can further comprise:

[0089] After forming the patterned second DBR reflective layer, the second substrate is removed to obtain a vertical cavity surface emitting laser.

[0090] Figure 10 is a structural schematic diagram after the step S150 is performed, as Figure 10 shown, the patterned second DBR reflective layer 90 is formed on the side of the patterned second epitaxial layer away from the patterned first DBR reflective layer.

[0091] Based on the same inventive concept, the present application also provides a vertical cavity surface emitting laser prepared by using the preparation method described in the above embodiments, and the specific structure of the vertical cavity surface emitting laser can be referred to Figure 10 .

[0092] The present application also performs optical pumping tests on the prepared VCSEL, Figure 11 is a schematic diagram of the relationship between the emission intensity and the pumping power density of the VCSEL prepared by using the preparation method provided by the present application, Figure 11 wherein the horizontal axis represents the pumping power density, the unit is MW / cm 2 , and the vertical axis represents the emission intensity, and it can be obtained from Figure 11 that the threshold pumping power density of the VCSEL prepared by the present application is 7.4 MW / cm 2 , that is, when the pumping power density reaches or exceeds 7.4 MW / cm 2 , lasing will occur Figure 12is a schematic diagram of emission spectrum of the VCSEL prepared by the preparation method provided by the application under different excitation levels, Figure 12 In the figure, the horizontal axis represents the lasing wavelength, and the unit is nm; the vertical axis represents the light emission intensity, Figure 12 The corresponding lasing wavelength and light emission intensity under different pump power densities are shown. The lasing wavelength of the VCSEL prepared by the application is 294 nm, that is, the application can prepare a deep ultraviolet VCSEL.

[0093] The technical solutions provided in the embodiments of the application have at least the following technical effects or advantages:

[0094] The vertical cavity surface emitting laser and the preparation method thereof provided by the embodiments of the application grow the first DBR reflection layer, the second epitaxial layer including the active layer and the sacrificial layer into two parts by forming the sacrificial layer during the epitaxial layer growth process, then patternize the first DBR reflection layer, the second epitaxial layer including the active layer and the sacrificial layer, to form at least one patterned structure on the side of the first epitaxial layer away from the first substrate, at this time, since the sacrificial layer is patternized, part of the sacrificial layer is exposed, which facilitates subsequent etching of the sacrificial layer by using the electrochemical etching method, to peel off the patterned second epitaxial layer and the patterned first DBR reflection layer from the first epitaxial layer as a whole, then bond the patterned first DBR reflection layer and the patterned second epitaxial layer after peeling off with the second substrate, and the patterned first DBR reflection layer is located between the patterned second epitaxial layer and the second substrate, at this time, the first DBR reflection layer is located at the bottom of the active layer, that is, can be used as the bottom DBR layer. Finally, form the patterned second DBR reflection layer on the side of the patterned second epitaxial layer away from the patterned first DBR reflection layer, as the top DBR layer, and the required vertical cavity surface emitting laser can be prepared. The application adopts the method of the sacrificial layer cooperating with the electrochemical etching, compared with the traditional laser peeling method, the electrochemical etching method has higher precision and controllability, can reduce the thermal shock and mechanical damage to the epitaxial layer, makes the surface of the second epitaxial layer after peeling off smoother, and by accurately controlling the electrochemical etching process, can reduce the cracking of each film layer in the second epitaxial layer and the generation of aluminum residues, thereby reducing the scattering loss of the VCSEL, improving the reliability and stability of the device, at the same time, can also reduce the preparation cost of the VCSEL, and improve the production efficiency.

[0095] In the specification provided herein, a large number of specific details are described. However, it can be understood that the embodiments of the application can be practiced without these specific details. In some examples, well-known methods, structures and techniques are not shown in detail in order not to obscure the understanding of the present specification.

[0096] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0097] It should be noted that the above embodiments are illustrative of the invention and not restrictive of the invention, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.

Claims

1. A method for fabricating a vertical-cavity surface-emitting laser, characterized in that, The preparation method includes: A first epitaxial layer, a sacrificial layer, a second epitaxial layer, and a first DBR reflective layer are sequentially formed on a first substrate, wherein the second epitaxial layer includes at least an active layer; The first DBR reflective layer, the second epitaxial layer, and the sacrificial layer are patterned to form at least one patterned structure on the side of the first epitaxial layer away from the first substrate. The patterned structure includes a patterned sacrificial layer, a patterned second epitaxial layer, and a patterned first DBR reflective layer. An electrochemical etching method is used to etch away the patterned sacrificial layer in the patterned structure, so as to peel the patterned second epitaxial layer and the patterned first DBR reflective layer as a whole from the first epitaxial layer; The stripped patterned first DBR reflective layer and the patterned second epitaxial layer are bonded to the second substrate, with the patterned first DBR reflective layer located between the patterned second epitaxial layer and the second substrate; A patterned second DBR reflective layer is formed on the side of the patterned second epitaxial layer away from the patterned first DBR reflective layer to obtain the vertical cavity surface-emitting laser.

2. The preparation method according to claim 1, characterized in that, The patterned first DBR reflective layer and the patterned second DBR reflective layer include a plurality of first reflective layers and a plurality of second reflective layers arranged alternately in sequence, wherein the first reflective layer and the second reflective layer are respectively an HfO2 layer and a SiO2 layer.

3. The preparation method according to claim 1, characterized in that, The step of bonding the stripped patterned first DBR reflective layer and the patterned second epitaxial layer to the second substrate includes: The patterned first DBR reflective layer and the patterned second epitaxial layer are picked up using an organic substrate after being stripped, with the patterned first DBR reflective layer located between the patterned second epitaxial layer and the organic substrate; The side of the organic substrate away from the patterned first DBR reflective layer and the patterned second epitaxial layer is bonded to the second substrate.

4. The preparation method according to claim 1, characterized in that, The method of etching away the patterned sacrificial layer in the patterned structure using electrochemical etching includes: Electrical contact material is welded to the edge of the first epitaxial layer, and the first epitaxial layer is electrically connected to the positive terminal of the power supply through the electrical contact material, and the negative terminal of the power supply is electrically connected to the cathode material. The first substrate, on which the first epitaxial layer and the patterned structure are formed, is placed in an electrolyte. The first epitaxial layer is used as the anode and the cathode material is used as the cathode to perform electrochemical etching on the patterned sacrificial layer in the patterned structure.

5. The preparation method according to claim 4, characterized in that, The electrical contact material is indium, and the cathode material is platinum.

6. The preparation method according to claim 1, characterized in that, The step of patterning the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer includes: A patterned photoresist layer is formed on the first DBR reflective layer; The first DBR reflective layer, the second epitaxial layer, and the sacrificial layer at the opening position of the photoresist layer are etched away to transfer the pattern on the photoresist layer to the first DBR reflective layer, the second epitaxial layer, and the sacrificial layer, forming the patterned first DBR reflective layer, the patterned second epitaxial layer, and the patterned sacrificial layer; Remove the patterned photoresist layer.

7. The preparation method according to claim 1, characterized in that, The sacrificial layer is an N-type doped AlGaN layer or an N-type doped GaN layer.

8. The preparation method according to claim 1, characterized in that, Both the first substrate and the second substrate are sapphire substrates. The first epitaxial layer includes a nucleation layer, a buffer layer and a current spreading layer sequentially stacked on the first substrate. The active layer includes a plurality of quantum well layers and a plurality of quantum barrier layers alternately arranged. The nucleation layer is made of AlN, and the buffer layer is made of Al. a Ga (1-a) N, the material of the current spreading layer includes Al. b Ga (1-b) N, the material of the quantum well layer includes Al k1 Ga (1-k1) N, the material of the quantum barrier layer includes Al k2 Ga (1-k2) N, a>0.5, b>0.5, k1>0.5, k2>0.

5.

9. The preparation method according to claim 8, characterized in that, The second epitaxial layer further includes a first resonant cavity adjustment layer and a second resonant cavity adjustment layer, wherein the first resonant cavity adjustment layer is located between the active layer and the sacrificial layer, and the second resonant cavity adjustment layer is located on the side of the active layer away from the sacrificial layer; Wherein, the first resonant cavity adjustment layer is Al c Ga (1-c) N layers, the second resonant cavity tuning layer is Al d Ga (1-d) For N layers, c > 0.5 and d > 0.

5.

10. A vertical-cavity surface-emitting laser, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 9.

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