Semiconductor laser and method for manufacturing the same

Abstract

Embodiments of the present application provide a semiconductor laser and a preparation method thereof, which include a substrate, a first confinement layer, a first waveguide layer, an active region, a second waveguide layer and a second confinement layer which are sequentially stacked on one side of the substrate; a ridge waveguide layer formed on one side of the second confinement layer; the ridge waveguide layer and the second confinement layer form a first etching groove in a direction perpendicular to the thickness of the substrate; a passivation layer formed on the groove wall of the first etching groove; a conductive layer formed on one side of the passivation layer; a first conductive member formed on one side of the ridge waveguide layer, and a second conductive member formed on the side of the substrate away from the first conductive member; the first conductive member is electrically connected to the conductive layer and the ridge waveguide layer. When the first conductive member and the second conductive member are connected to a power supply, an electric field can be formed in the conductive layer, so that the carriers in the ridge waveguide layer can be away from the side wall of the ridge waveguide layer, the carriers in the ridge waveguide layer are more concentrated, thereby improving the injection efficiency of the carriers, and the optical field can be optimized, and the beam quality of the semiconductor laser is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor lasers, in particular to a semiconductor laser and a preparation method thereof. BACKGROUND

[0002] Semiconductor lasers play an important role in the fields of optical communication, display lighting, laser processing, etc. However, the traditional semiconductor laser has a current spreading effect, that is, the current will diffuse during the lateral transmission process, resulting in uneven current density distribution in the active region, which further greatly increases the threshold current and degrades the light field distribution, thereby restricting the output performance of the semiconductor laser.

[0003] The traditional semiconductor laser often adopts a ridge structure design, and a ridge waveguide layer is formed by selective etching. The ridge waveguide layer can effectively realize current concentrated injection and light field mode regulation, thereby improving the output performance of the laser.

[0004] However, the etching process inevitably introduces defects such as lattice damage and dangling bonds on the sidewall of the ridge waveguide layer. These defects not only become non-radiative recombination centers, reducing the carrier injection efficiency, but also interfere with the light field distribution, affecting the beam quality. SUMMARY

[0005] The semiconductor laser and the preparation method thereof provided by the embodiments of the present application make the carriers in the ridge waveguide layer more concentrated, thereby improving the efficiency of carrier injection into the active region, optimizing the light field, and further improving the beam quality of the semiconductor laser.

[0006] In a first aspect, the embodiments of the present application provide a semiconductor laser, comprising:

[0007] a substrate, a first confinement layer, a first waveguide layer, an active region, a second waveguide layer, and a second confinement layer; the first confinement layer, the first waveguide layer, the active region, the second waveguide layer, and the second confinement layer are sequentially stacked on one side of the substrate in the thickness direction;

[0008] a ridge waveguide layer formed on the side of the second confinement layer away from the substrate; at least one side of the ridge waveguide layer forms a first etching groove with the second confinement layer in the thickness direction perpendicular to the substrate;

[0009] a passivation layer formed on the groove wall of the first etching groove;

[0010] a conductive layer formed on the side of the passivation layer away from the ridge waveguide layer and the second confinement layer;

[0011] A first conductive member and a second conductive member, the first conductive member is formed on a side of the ridge waveguide layer away from the substrate, and the second conductive member is formed on a side of the substrate away from the first conductive member; the first conductive member electrically connects the conductive layer and the ridge waveguide layer.

[0012] In a possible implementation, the material of the conductive layer is at least one of indium tin oxide, indium gallium zinc oxide and graphene.

[0013] In a possible implementation, the passivation layer is an insulating medium layer.

[0014] In a possible implementation, a side of the passivation layer away from the ridge waveguide layer and the second confinement layer forms a second etching groove, and the conductive layer is formed on a groove wall of the second etching groove.

[0015] In a possible implementation, the thickness of the passivation layer is D, where 5nm≤D≤300nm.

[0016] In a possible implementation, the first confinement layer and the first waveguide layer are N-type doped; and the second confinement layer, the second waveguide layer and the ridge waveguide layer are P-type doped.

[0017] In a possible implementation, the thickness of the ridge waveguide layer along the thickness direction of the substrate is H, where 100nm≤H≤500nm.

[0018] In a possible implementation, the ridge waveguide layer has a first connecting wall and a second connecting wall in opposite positions along the thickness direction, the first connecting wall electrically connects the first conductive member, and the second connecting wall electrically connects the second confinement layer.

[0019] Along the thickness direction of the substrate, the first connecting wall forms a first orthographic projection on the substrate, and the second connecting wall forms a second orthographic projection on the substrate, and the second orthographic projection covers the first orthographic projection.

[0020] In a possible implementation, along a direction close to the substrate, the ridge waveguide layer gradually increases along a cross section perpendicular to the thickness direction of the substrate.

[0021] In a second aspect, an embodiment of the present application provides a preparation method of a semiconductor laser, comprising,

[0022] providing a substrate, and sequentially stacking a first confinement layer, a first waveguide layer, an active region, a second waveguide layer and a second confinement layer on a side of the substrate along a thickness direction of the substrate;

[0023] A ridge waveguide layer is formed on the side of the second confinement layer away from the substrate, and at least one side of the ridge waveguide layer forms a first etching groove with the second confinement layer in the thickness direction perpendicular to the substrate;

[0024] A passivation layer is formed on the groove wall of the first etching groove;

[0025] A conductive layer is formed on the side of the passivation layer away from the ridge waveguide layer and the second confinement layer;

[0026] A first conductive member is formed on the side of the ridge waveguide layer away from the substrate, and a second conductive member is formed on the side of the substrate away from the first conductive member, and the first conductive member is electrically connected to the conductive layer.

[0027] The semiconductor laser and the preparation method thereof provided by the embodiments of the present application can form an electric field in the conductive layer when the first conductive member and the second conductive member are connected to a power supply, and the carriers in the ridge waveguide layer close to the side wall of the ridge waveguide layer can move towards the middle position of the ridge waveguide layer under the action of the electric field, so that the carriers in the ridge waveguide layer can move away from the side wall of the ridge waveguide layer, a depletion layer is formed at the side wall of the ridge waveguide layer, the carriers in the ridge waveguide layer are prevented from being captured by the defects at the side wall of the ridge waveguide layer, the carriers in the ridge waveguide layer can be more concentrated, the efficiency of injecting the carriers in the ridge waveguide layer into the active region is improved, the threshold current of the semiconductor laser is effectively reduced, the loss of the semiconductor laser is reduced, the optical field is optimized, and the beam quality of the semiconductor laser is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the application.

[0029] Figure 1 The schematic diagram provided by some embodiments of the present application for growing a first confinement layer, a first waveguide layer, an active region, a second waveguide layer and a second confinement layer on a substrate;

[0030] Figure 2 The schematic diagram provided by some embodiments of the present application for growing a third waveguide layer on a second confinement layer;

[0031] Figure 3 The first schematic diagram provided by some embodiments of the present application for forming a ridge waveguide layer by etching;

[0032] Figure 4 The second schematic diagram provided by some embodiments of the present application for forming a ridge waveguide layer by etching;

[0033] Figure 5 A schematic diagram of forming a passivation layer in a first etching groove provided for some embodiments of the present application;

[0034] Figure 6 A schematic diagram of etching the passivation layer to form a second etching groove provided for some embodiments of the present application;

[0035] Figure 7 A schematic diagram of forming a conductive layer in the second etching groove provided for some embodiments of the present application;

[0036] Figure 8 A schematic diagram of a structure of a semiconductor laser provided for some embodiments of the present application;

[0037] Figure 9 A schematic diagram of a comparison of a valence band change at a sidewall of a ridge waveguide layer along a thickness direction perpendicular to a substrate between some embodiments of the present application and the related art, wherein a solid line represents the valence band change of some embodiments of the present application, and a dashed line represents the valence band change of the related art;

[0038] Figure 10 A schematic diagram of a comparison of a hole concentration change in a ridge waveguide layer along a thickness direction perpendicular to a substrate between some embodiments of the present application and the related art, wherein a solid line represents the hole concentration change of some embodiments of the present application, and a dashed line represents the hole concentration change of the related art;

[0039] Figure 11 A flowchart of a preparation method of a semiconductor laser provided for some embodiments of the present application.

[0040] Reference signs:

[0041] 100, substrate; 110, second conductive member;

[0042] 200, first confinement layer;

[0043] 300, first waveguide layer;

[0044] 400, active region;

[0045] 500, second waveguide layer;

[0046] 600, second confinement layer;

[0047] 700, third waveguide layer; 710, ridge waveguide layer; 711, first conductive member; 712, first connecting wall; 713, second connecting wall; 720, first etching groove;

[0048] 800, passivation layer; 810, second etching groove;

[0049] 900, conductive layer.

[0050] The specific embodiments of the application have been shown by way of example in the above figures, and will be described in more detail hereafter. These figures and this written description are not intended to limit the scope of the inventive concept in any way, but rather to illustrate the inventive concept to one of ordinary skill in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0051] Exemplary embodiments will be described in detail with reference to the drawings, of which examples are shown. Unless otherwise noted, the same numbers on different drawings and / or in different drawings indicate the same or similar elements. The following detailed description does not limit the application, as claimed, in any way. Rather, it is intended to describe some ways in which the application can be put into practice.

[0052] Semiconductor lasers play an important role in the fields of optical communication, display lighting, laser processing, etc. However, the conventional semiconductor laser has a current spreading effect, that is, the current diffuses during lateral transmission, resulting in uneven current density distribution in the active region, which greatly increases the threshold current and degrades the light field distribution, thereby restricting the output performance of the semiconductor laser.

[0053] The conventional semiconductor laser often adopts a ridge structure design, and a ridge waveguide layer is formed by selective etching, which can effectively realize current concentrated injection and light field mode regulation, thereby improving the output performance of the laser.

[0054] However, the etching process inevitably introduces defects such as lattice damage and dangling bonds on the sidewall of the ridge waveguide layer. These defects not only become non-radiative recombination centers, reducing the carrier injection efficiency, but also interfere with the light field distribution, affecting the beam quality.

[0055] The semiconductor laser and the preparation method thereof provided by the application can form an electric field in the conductive layer when the first conductive part and the second conductive part are connected with the power supply, and the carriers in the ridge waveguide layer close to the sidewall of the ridge waveguide layer can move toward the middle position of the ridge waveguide layer under the action of the electric field, thereby making the carriers in the ridge waveguide layer away from the sidewall of the ridge waveguide layer, forming a depletion layer at the sidewall of the ridge waveguide layer, avoiding the capture of the carriers in the ridge waveguide layer by the defects at the sidewall of the ridge waveguide layer, and making the carriers in the ridge waveguide layer more concentrated, thereby improving the efficiency of the carrier injection from the ridge waveguide layer to the active region, effectively reducing the threshold current of the semiconductor laser, reducing the loss of the semiconductor laser, optimizing the light field, and further improving the beam quality of the semiconductor laser.

[0056] The technical solutions of the present application and how the technical solutions solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples. The embodiments of the present application will be described below with reference to the drawings.

[0057] In a first aspect, referring to Figure 8 As shown in the drawings, the embodiments of the present application provide a semiconductor laser, which can be an FP laser (Fabry-Perot laser), a fiber Bragg grating laser, or a distributed feedback laser, etc., which is not particularly limited, and the semiconductor laser of the embodiments of the present application is a gallium nitride-based blue-green laser.

[0058] The semiconductor laser of the embodiments of the present application includes a substrate 100, the substrate 100 has a thickness direction X, along the thickness direction X of the substrate 100, a first confinement layer 200 is formed on one side of the substrate 100, a first waveguide layer 300 is formed on the side of the first confinement layer 200 away from the substrate 100, an active region 400 is formed on the side of the first waveguide layer 300 away from the substrate 100, a second waveguide layer 500 is formed on the side of the active region 400 away from the substrate 100, and a second confinement layer 600 is formed on the side of the second waveguide layer 500 away from the substrate 100, wherein the type of the active region 400 is a quantum well active region. The semiconductor laser of the embodiments of the present application, the refractive index of the first confinement layer 200 is less than that of the first waveguide layer 300, and the refractive index of the second confinement layer 600 is less than that of the second waveguide layer 500, so that in actual application, the first confinement layer 200 and the second confinement layer 600 can confine the light beam to propagate in the first waveguide layer 300, the active region 400 and the second waveguide layer 500, avoiding the light beam to pass through the first confinement layer 200 or the second confinement layer 600.

[0059] Further, referring to Figures 3-7 As shown in the drawings, a ridge waveguide layer 710 is formed on the side of the second confinement layer 600 away from the substrate 100, and the width dimension of the ridge waveguide layer 710 is less than that of the second confinement layer 600 along the thickness direction X perpendicular to the substrate 100, so that at least one first etching groove 720 can be formed on the side of the ridge waveguide layer 710. The design of the ridge waveguide layer 710 can confine the formed light field in the first waveguide layer 300, the active region 400 and the second waveguide layer 500, especially in the vicinity of the active region 400, to improve the condensation of the light field, realize the regulation of the light field, and improve the output performance of the semiconductor laser of the embodiments of the present application.

[0060] It can be understood that the ridge waveguide layer 710 is formed by deposition, etching and other processes. According to different etching positions, at least one side of the ridge waveguide layer 710 can form the first etching groove 720 along the thickness direction X perpendicular to the substrate 100, that is, the number of the first etching groove 720 in the embodiment of the application can be one or two. In the embodiment of the application, in the process of forming the first etching groove 720 on the ridge waveguide layer 710 by etching, the first etching groove 720 is directly etched to the side of the second confinement layer 600 away from the substrate 100, so that the first etching groove 720 is directly connected with the second confinement layer 600. More specifically, the groove wall of the first etching groove 720 is composed of the side wall of the second confinement layer 600 away from the substrate 100 and the side wall of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100.

[0061] Further, in the embodiment of the application, as shown in Figures 5-8 The passivation layer 800 is formed on the groove wall of the first etching groove 720. The passivation layer 800 is an insulating medium layer. The passivation layer 800 can effectively isolate the external air and water vapor, avoid the external air and water vapor from contacting the second confinement layer 600, and avoid the external air and water vapor from contacting the ridge waveguide layer 710, thereby effectively ensuring the stability of the second confinement layer 600 and the ridge waveguide layer 710 and improving the stability and quality of the output light beam of the semiconductor laser. The refractive index of the passivation layer 800 in the embodiment of the application is smaller than that of the ridge waveguide layer 710, so as to avoid the light beam from being emitted to the outside of the semiconductor laser through the passivation layer 800, thereby causing unnecessary loss.

[0062] Further, as shown in Figure 8 The first conductive member 711 is formed on the side of the ridge waveguide layer 710 away from the substrate 100, and the second conductive member 110 is formed on the side of the substrate 100 away from the first conductive member 711. The first conductive member 711 can act as an anode electrode, and the second conductive member 110 can act as a cathode electrode. When the first conductive member 711 and the second conductive member 110 are connected with a power supply, a current will be formed in the ridge waveguide layer 710, the second confinement layer 600, the second waveguide layer 500, the active region 400, the first waveguide layer 300 and the first confinement layer 200. The flow direction of the current is from the first conductive member 711 to the second conductive member 110. In this process, the carriers existing in the ridge waveguide layer 710, the second confinement layer 600, the second waveguide layer 500, the first waveguide layer 300 and the first confinement layer 200 will converge in the active region 400, thereby enabling the semiconductor laser in the embodiment of the application to generate a light beam and output the light beam.

[0063] It should be noted that, since the width dimension of the ridge waveguide layer 710 is smaller than the width dimension of the second confinement layer 600 along the thickness direction X perpendicular to the substrate 100, and the passivation layer 800 is formed on the groove wall of the first etching groove 720, when the first conductive member 711 and the second conductive member 110 are connected with the power supply, the formed current flows towards the second conductive member 110 in the ridge waveguide layer 710 with the smaller width dimension, and is concentrated under the restriction of the ridge waveguide layer 710, so that the carriers can be more concentratedly injected into the active region 400, the injection efficiency of the carriers can be effectively improved, and the threshold current of the semiconductor laser can be reduced.

[0064] Since the etching process inevitably causes lattice damage, dangling bonds and other defects on the sidewall of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100 in the process of forming the ridge waveguide layer 710 by etching, these defects not only become non-radiative recombination centers, affecting the efficiency of carrier injection into the active region 400, but also interfere with the light field distribution, affecting the quality of the light beam; more specifically, when the first conductive member 711 and the second conductive member 110 are connected with the power supply, the carriers in the ridge waveguide layer 710 exist in the case of diffusion along the thickness direction X perpendicular to the substrate 100, so that the carriers in the ridge waveguide layer 710 can be captured by the defects at the sidewall of the ridge waveguide layer 710, and the semiconductor laser can be heated, so that the loss of the semiconductor laser is increased. Similarly, since the first etching groove 720 directly communicates with the sidewall of the second confinement layer 600 away from the substrate 100, the sidewall of the second confinement layer 600 away from the substrate 100 also has lattice damage, dangling bonds and other defects, so that these defects not only become non-radiative recombination centers, affecting the efficiency of carrier injection into the active region 400, but also interfere with the light field distribution, affecting the quality of the light beam; more specifically, when the first conductive member 711 and the second conductive member 110 are connected with the power supply, the carriers in the second confinement layer 600 and the second waveguide layer 500 exist in the case of diffusion along the thickness direction X perpendicular to the substrate 100, so that the carriers in the second confinement layer 600 and the second waveguide layer 500 can be captured by the defects at the sidewall of the second confinement layer 600, and the semiconductor laser can be heated, so that the loss of the semiconductor laser is increased.

[0065] In the embodiment of the present application, referring to Figure 7 and Figure 8As shown, after the passivation layer 800 is formed on the sidewall of the first etching groove 720, the conductive layer 900 is further formed on the side of the passivation layer 800 away from the ridge waveguide layer 710 and the second confinement layer 600, which is equivalent to that the conductive layer 900 is formed on the side of the passivation layer 800 away from the ridge waveguide layer 710 and on the side of the passivation layer 800 away from the second confinement layer 600, and then the first conductive member 711 is formed on the side of the ridge waveguide layer 710 away from the substrate 100. The first conductive member 711 is not only electrically connected with the ridge waveguide layer 710, but also electrically connected with the conductive layer 900.

[0066] It should be noted that, in the embodiment of the present application, the conductive layer 900 has poor air and moisture isolation capability due to its conductive property. Therefore, the passivation layer 800 is formed between the conductive layer 900 and the ridge waveguide layer 710 and the second confinement layer 600. The passivation layer 800 is an insulating medium layer, which has better isolation effect and can isolate air and moisture, thereby effectively improving the stability of the ridge waveguide layer 710 and the second confinement layer 600. When the conductive layer 900 directly contacts the ridge waveguide layer 710, an ohmic contact is formed between the conductive layer 900 and the ridge waveguide layer 710, which leads to the occurrence of tunneling. Similarly, when the conductive layer 900 directly contacts the second confinement layer 600, an ohmic contact is formed between the conductive layer 900 and the second confinement layer 600, which leads to the occurrence of tunneling. Therefore, the passivation layer 800 can isolate and protect the conductive layer 900 from the ridge waveguide layer 710 and the second confinement layer 600.

[0067] When the first conductive member 711 and the second conductive member 110 are connected with the power supply, an electric field can be formed in the conductive layer 900. Along the thickness direction X of the substrate 100, the carriers in the ridge waveguide layer 710 close to the sidewall of the ridge waveguide layer 710 can move towards the middle position of the ridge waveguide layer 710 under the action of the electric field, thereby making the carriers in the ridge waveguide layer 710 away from the sidewall of the ridge waveguide layer 710, so that a depletion layer is formed at the sidewall of the ridge waveguide layer 710, avoiding the carriers in the ridge waveguide layer 710 being captured by the defects at the sidewall of the ridge waveguide layer 710.

[0068] Similarly, when the electric field is formed in the conductive layer 900, along the thickness direction X of the substrate 100, the carriers in the second confinement layer 600 close to the sidewall of the second confinement layer 600 away from the substrate 100 can move towards the active region 400 under the action of the electric field, thereby making the carriers in the second confinement layer 600 away from the sidewall of the second confinement layer 600, so that a depletion layer is formed at the sidewall of the second confinement layer 600, avoiding the carriers in the second confinement layer 600 being captured by the defects at the sidewall of the second confinement layer 600.

[0069] It is worth mentioning that, in the ridge waveguide layer 710, along the thickness direction X perpendicular to the substrate 100, the carriers at the sidewall of the ridge waveguide layer 710 move towards the middle position of the ridge waveguide layer 710, so that the carriers in the ridge waveguide layer 710 are more concentrated, thereby improving the efficiency of the carriers in the ridge waveguide layer 710 injecting into the active region 400, effectively reducing the threshold current of the semiconductor laser, reducing the loss of the semiconductor laser, and optimizing the optical field, and further improving the beam quality of the semiconductor laser.

[0070] Similarly, in the second confinement layer 600, along the thickness direction X of the substrate 100, the carriers in the second confinement layer 600 and the second waveguide layer 500 move towards the active region 400, thereby avoiding the diffusion of the carriers in the second confinement layer 600 and the second waveguide layer 500 in the thickness direction X perpendicular to the substrate 100, so that the carriers in the second confinement layer 600 and the second waveguide layer 500 are more concentrated, thereby improving the efficiency of the carriers in the second confinement layer 600 and the second waveguide layer 500 injecting into the active region 400, effectively reducing the threshold current of the semiconductor laser, reducing the loss of the semiconductor laser, and optimizing the optical field, and further improving the beam quality of the semiconductor laser.

[0071] In the embodiment of the present application, as shown in Figures 3-8 That is to say, in the embodiment of the present application, the number of the first etching groove 720 is two, and correspondingly, the passivation layer 800 and the conductive layer 900 are formed at each first etching groove 720. In the embodiment of the present application, when the first conductive part 711 and the second conductive part 110 are connected to the power supply, an electric field is formed on both sides of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100, thereby making the carriers in the ridge waveguide layer 710 more concentrated, thereby improving the efficiency of the carriers in the ridge waveguide layer 710 injecting into the active region 400, effectively reducing the threshold current of the semiconductor laser, reducing the loss of the semiconductor laser, and optimizing the optical field, and further improving the beam quality of the semiconductor laser.

[0072] In some embodiments, the material of the conductive layer 900 is at least one of indium tin oxide, indium gallium zinc oxide, and graphene.

[0073] Exemplarily, in the embodiment of the present application, the material of the conductive layer 900 is selected to be indium tin oxide. Since the indium tin oxide is a high transparent conductive oxide, when an electric field is formed in the conductive layer 900, a depletion layer is formed between the conductive layer 900 and the ridge waveguide layer 710, and a depletion layer is formed between the conductive layer 900 and the second confinement layer 600. The depletion layer can effectively block the movement of the carriers towards the defects at the sidewalls of the ridge waveguide layer 710 and the second confinement layer 600, and can promote the carriers in the ridge waveguide layer 710 and the second confinement layer 600 and the second waveguide layer 500 to be more concentratedly injected into the active region 400, thereby improving the injection efficiency of the carriers.

[0074] Further, the indium tin oxide has high conductivity and low optical loss characteristics in the visible light band, which can significantly reduce the series resistance and transmission loss of the device, and realize the double optimization of reducing the threshold current and improving the output power of the semiconductor laser.

[0075] In some embodiments, the thickness of the passivation layer 800 is D, where 5nm≤D≤300nm.

[0076] It can be understood that when the first conductive part 711 and the second conductive part 110 are connected to a power supply, the electric field formed in the conductive layer 900 has a certain range. When the thickness of the passivation layer 800 is less than 5nm, the effect of the passivation layer 800 on isolating air and water vapor is affected, and the range of the electric field in the ridge waveguide layer 710 is too large. When the thickness of the passivation layer 800 is greater than 300nm, the range of the electric field in the ridge waveguide layer 710 and the second confinement layer 600 is too small, and the carriers in the ridge waveguide layer 710 and the second confinement layer 600 are close to the defects at the sidewalls, which cannot effectively prevent the carriers from being captured by the defects at the sidewalls of the ridge waveguide layer 710 and the second confinement layer 600.

[0077] In some embodiments, the first confinement layer 200 and the first waveguide layer 300 are both N-type doped, so that the type of the carriers in the first confinement layer 200 and the first waveguide layer 300 is a hole; and the second waveguide layer 500, the second confinement layer 600 and the ridge waveguide layer 710 are all P-type doped, so that the type of the carriers in the second waveguide layer 500, the second confinement layer 600 and the ridge waveguide layer 710 is an electron.

[0078] When the first conductive member 711 and the second conductive member 110 are connected with the power supply, the current is formed in the ridge waveguide layer 710, the second confinement layer 600, the second waveguide layer 500, the active region 400, the first waveguide layer 300 and the first confinement layer 200, so that the holes in the ridge waveguide layer 710, the second confinement layer 600 and the second waveguide layer 500 move towards the active region 400, and the electrons in the first waveguide layer 300 and the first confinement layer 200 move towards the active region 400, when the holes and the electrons combine in the active region 400, the semiconductor laser of the embodiment of the present application can further generate a laser beam.

[0079] It should be noted that in the embodiment of the present application, the electric field formed in the conductive layer 900 moves the holes at the sidewall of the ridge waveguide layer 710 towards the middle position of the ridge waveguide layer 710, so that the holes in the ridge waveguide layer 710 are more concentrated, and moves the holes at the sidewall of the second confinement layer 600 towards the position of the active region 400, so that the holes in the second confinement layer 600 and the second waveguide layer 500 are more concentrated, so that the holes in the ridge waveguide layer, the second confinement layer 600 and the second waveguide layer 500 can be more concentratedly injected into the active region 400, the efficiency of hole injection can be improved, the threshold current of the semiconductor laser can be reduced, the loss of the semiconductor laser can be reduced, the light field can be optimized, and the beam quality of the semiconductor laser can be further improved.

[0080] Since the holes in the ridge waveguide layer 710 can move away from the defects at the sidewall of the ridge waveguide layer 710 under the influence of the electric field, the holes in the ridge waveguide layer 710 can be avoided to be captured by the defects at the sidewall of the ridge waveguide layer 710, unnecessary loss of holes is avoided, the hole concentration in the ridge waveguide layer 710 is effectively ensured, and the situation of heating of the semiconductor laser is reduced. Similarly, since the holes in the second confinement layer 600 and the second waveguide layer 500 can move away from the defects at the sidewall of the second confinement layer 600 under the influence of the electric field, the holes in the second confinement layer 600 and the second waveguide layer 500 can be avoided to be captured by the defects at the sidewall of the second confinement layer 600, unnecessary loss of holes is avoided, the hole concentration in the second confinement layer 600 and the second waveguide layer 500 is effectively ensured, and the situation of heating of the semiconductor laser is reduced.

[0081] In some embodiments, the conductive layer 900 can not be subjected to a doping treatment, or can be subjected to a doping treatment. For example, in the embodiment of the present application, the conductive layer 900 is N-type doped.

[0082] It should be noted that regardless of whether the conductive layer 900 is doped or not, when the conductive layer 900 directly contacts the ridge waveguide layer 710 and the second confinement layer 600, ohmic contacts will be formed between the conductive layer 900 and the ridge waveguide layer 710, as well as between the conductive layer 900 and the second confinement layer 600, leading to tunneling. Therefore, it is necessary to isolate the conductive layer 900 from the ridge waveguide layer 710 and from the second confinement layer 600 through the passivation layer 800.

[0083] In this embodiment of the application, when the first conductive element 711 is connected to the second conductive element 110 and the power supply, a depletion layer is formed between the conductive layer 900 and the ridge waveguide layer 710. The depletion layer is also called a barrier region. See [link to relevant documentation]. Figure 9 As shown in this embodiment, by optimizing the valence band at the sidewall of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100, the movement of holes in the ridge waveguide layer 710 toward defects at the sidewall of the ridge waveguide layer 710 can be better prevented. Similarly, by optimizing the valence band at the sidewall of the second confinement layer 600 facing away from the substrate 100, the movement of holes in the second confinement layer 600 and the second waveguide layer 500 toward defects at the sidewall of the second confinement layer 600 can be better prevented. See also... Figure 10 As shown, in the lateral distance of the ridge waveguide layer 710, due to the electric field of the conductive layer 900, the hole concentration in the ridge waveguide layer 710, the second confinement layer 600, and the second waveguide layer 500 along the thickness direction X perpendicular to the substrate 100 exhibits a pattern of low concentration on both sides and high concentration in the middle. This also reflects that the holes in the ridge waveguide layer 710, the second confinement layer 600, and the second waveguide layer 500 are more concentrated, which can improve the hole injection efficiency of the active region 400, reduce the threshold current of the semiconductor laser, reduce the loss of the semiconductor laser, optimize the optical field, and further improve the beam quality of the semiconductor laser.

[0084] In some embodiments, the thickness dimension of the ridge waveguide layer 710 along the thickness direction X of the substrate 100 is H, wherein 100nm≤H≤500nm.

[0085] In some implementations, see Figures 3-8 As shown, along the thickness direction X of the substrate 100, the ridge waveguide layer 710 has a first connecting wall 712 and a second connecting wall 713 positioned opposite each other, wherein the first connecting wall 712 is further away from the substrate 100 than the second connecting wall 713, the first connecting wall 712 is electrically connected to the first conductive element 711, and the second connecting wall 713 is electrically connected to the second confinement layer 600.

[0086] Furthermore, along the thickness direction X of the substrate 100, the first connecting wall 712 of this application embodiment can form a first orthographic projection on the substrate 100, and the second connecting wall 713 can form a second orthographic projection on the substrate 100, wherein the second orthographic projection completely covers the first orthographic projection.

[0087] It is understood that, in this embodiment of the application, the second orthographic projection is designed to completely cover the first orthographic projection. That is, the area of ​​the second connecting wall 713 is not less than the area of ​​the first connecting wall 712. More specifically, the area of ​​the first connecting wall 712 can be less than the area of ​​the second connecting wall 713, or the area of ​​the first connecting wall 712 can be equal to the area of ​​the second connecting wall 713. For a more vivid illustration, see [link to relevant documentation]. Figure 4 As shown, when the area of ​​the first connecting wall 712 is equal to the area of ​​the second connecting wall 713, the cross-sectional shape of the ridge waveguide layer 710 is square. (See attached image.) Figure 3 and Figures 5-8 As shown, when the area of ​​the first connecting wall 712 is smaller than the area of ​​the second connecting wall 713, the cross-sectional shape of the ridge waveguide layer 710 is trapezoidal.

[0088] In some implementations, see Figure 3 and Figures 5-8 As shown, along the direction close to the substrate 100, the cross-section of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100 gradually increases. That is, the area of ​​the first connecting wall 712 is smaller than the area of ​​the second connecting wall 713, which makes the cross-sectional shape of the ridge waveguide layer 710 trapezoidal. This makes at least one sidewall of the ridge waveguide layer 710 and the second confinement layer 600 have a certain tilt angle along the thickness direction X perpendicular to the substrate 100, which makes it easier to form the ridge waveguide layer 710 by etching process, and also makes it easier to form the passivation layer 800 on the sidewall of the ridge waveguide layer 710.

[0089] In this embodiment, the area of ​​the first connecting wall 712 is smaller than the area of ​​the second connecting wall 713, and the cross-sectional shape of the ridge waveguide layer 710 is an isosceles trapezoid.

[0090] Along the thickness direction X perpendicular to the substrate 100, since the two sidewalls of the ridge waveguide layer 710 are inclined at a certain angle to the second confinement layer 600, it is easy to form the ridge waveguide layer 710 by etching process, and it is also easier to form the passivation layer 800 on the sidewalls of the ridge waveguide layer 710; and the sidewall of the formed passivation layer 800 away from the ridge waveguide layer 710 is also inclined at a certain angle to the second confinement layer 600, which makes it easy to form the conductive layer 900 on the side of the passivation layer 800 away from the ridge waveguide layer 710.

[0091] Secondly, see Figure 11As shown, the embodiment of the present application provides a preparation method of a semiconductor laser.

[0092] The preparation method of the embodiment of the present application comprises the following steps:

[0093] In step S100, a substrate is provided, and a first confinement layer, a first waveguide layer, an active region, a second waveguide layer and a second confinement layer are sequentially stacked on one side of the substrate in the thickness direction of the substrate.

[0094] In this step, the substrate 100 is placed in the MOCVD device growth chamber, as shown in Figure 1 As shown, the second confinement layer 600, the second waveguide layer 500, the active region 400, the first waveguide layer 300 and the first confinement layer 200 are sequentially grown on one side of the substrate 100 in the thickness direction X of the substrate 100, thereby obtaining the epitaxial structure of the semiconductor laser of the embodiment of the present application.

[0095] Further, in the process of sequentially growing the second confinement layer 600, the second waveguide layer 500, the active region 400, the first waveguide layer 300 and the first confinement layer 200, the second confinement layer 600 and the second waveguide layer 500 are P-type doped, and the first waveguide layer 300 and the first confinement layer 200 are N-type doped.

[0096] In step S200, a ridge waveguide layer is formed on the side of the second confinement layer away from the substrate, and at least one side of the ridge waveguide layer forms a first etching groove with the second confinement layer in the thickness direction perpendicular to the substrate.

[0097] In this step, the process continues in the MOCVD device growth chamber, as shown in Figure 2 As shown, the third waveguide layer 700 is grown on the side of the second confinement layer 600 away from the substrate 100, as shown in Figure 3 and Figure 4 As shown, at least one side of the third waveguide layer 700 is selectively etched in the thickness direction X perpendicular to the substrate 100 by a photolithography and dry etching process, so that at least one side of the ridge waveguide layer 710 can form the first etching groove 720 with the second confinement layer 600.

[0098] In the embodiment of the present application, both sides of the third waveguide layer 700 are etched in the thickness direction X perpendicular to the substrate 100, so that both sides of the ridge waveguide layer 710 can form the first etching groove 720 with the second confinement layer 600.

[0099] In step S300, a passivation layer is formed on the groove wall of the first etching groove.

[0100] In this step, as shown in Figure 5As shown in the figure, the passivation layer 800 is deposited on the sidewalls of the two first etching grooves 720, and the passivation layer 800 is also deposited on the first connecting wall 712 of the ridge waveguide layer 710.

[0101] In step S400, a conductive layer is formed on the side of the passivation layer away from the ridge waveguide layer and the second confinement layer.

[0102] In this step, referring to Figure 6 As shown in the figure, the passivation layer 800 in each first etching groove 720 is etched, so that a second etching groove 810 is formed on the corresponding passivation layer 800. Specifically, the second etching groove 810 is formed on the side of the passivation layer 800 away from the ridge waveguide layer 710 and the second confinement layer 600, as shown in the figure. Figure 7 As shown in the figure, the conductive layer 900 is deposited on the sidewall of the second etching groove 810.

[0103] It should be noted that in the embodiments of the present application, the conductive layer 900 can be N-doped, or the conductive layer 900 can not be doped.

[0104] In step S500, a first conductive member is formed on the side of the ridge waveguide layer away from the substrate, and a second conductive member is formed on the side of the substrate away from the first conductive member, and the first conductive member is electrically connected to the conductive layer.

[0105] In this step, referring to Figure 8 As shown in the figure, first, the passivation layer 800 on the first connecting wall 712 is removed by etching process, so that the first connecting wall 712 is exposed, then the first conductive member 711 is deposited on the first connecting wall 712 and the conductive layer 900, and finally the second conductive member 110 is deposited on the side of the substrate 100 away from the first conductive member 711.

[0106] Finally, it should be noted that other embodiments of the present application will be easily conceived by those skilled in the art after considering the specification and practicing the disclosed application. The present application is intended to cover any variations, uses, or adaptive changes of the present application that follow the general principles of the present application and include common knowledge or conventional technical means in the art that are not disclosed in the present application, and is not limited to the precise structure described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is only limited by the appended claims.

Claims

1. A semiconductor laser, characterized by, The application relates to a ridge waveguide structure, comprising: a substrate (100), a first confinement layer (200), a first waveguide layer (300), an active region (400), a second waveguide layer (500) and a second confinement layer (600); the first confinement layer (200), the first waveguide layer (300), the active region (400), the second waveguide layer (500) and the second confinement layer (600) are sequentially stacked on one side of the substrate (100) in the thickness direction; a ridge waveguide layer (710) formed on the side of the second confinement layer (600) away from the substrate (100); at least one side of the ridge waveguide layer (710) is provided with a first etching groove (720) formed in the thickness direction perpendicular to the substrate (100); a passivation layer (800) formed on the groove wall of the first etching groove (720); a conductive layer (900) formed on the side of the passivation layer (800) away from the ridge waveguide layer (710) and the second confinement layer (600); a first conductive part (711) formed on the side of the ridge waveguide layer (710) away from the substrate (100) and a second conductive part (110) formed on the side of the substrate (100) away from the first conductive part (711); the first conductive part (711) is electrically connected to the conductive layer (900) and the ridge waveguide layer (710).

2. The semiconductor laser of claim 1, wherein: The material of the conductive layer (900) is at least one of indium tin oxide, indium gallium zinc oxide and graphene.

3. The semiconductor laser of claim 1, wherein: The passivation layer (800) is an insulating medium layer.

4. The semiconductor laser of any of claims 1-3, wherein: The side of the passivation layer (800) away from the ridge waveguide layer (710) and the second confinement layer (600) is provided with a second etching groove (810), and the conductive layer (900) is formed on the groove wall of the second etching groove (810).

5. The semiconductor laser of claim 4, wherein: The thickness dimension of the passivation layer (800) is D, wherein 5nm<=D<=300nm.

6. The semiconductor laser of any of claims 1-3 and 5, wherein: The first confinement layer (200) and the first waveguide layer (300) are N-type doped; the second confinement layer (600), the second waveguide layer (500) and the ridge waveguide layer (710) are P-type doped.

7. The semiconductor laser of any of claims 1-3 and 5, wherein: The thickness dimension of the ridge waveguide layer (710) in the thickness direction of the substrate (100) is H, wherein 100nm<=H<=500nm.

8. The semiconductor laser of any of claims 1-3 and 5, wherein: The ridge waveguide layer (710) has a first connecting wall (712) and a second connecting wall (713) opposite in the thickness direction, the first connecting wall (712) is electrically connected to the first conductive part (711), and the second connecting wall (713) is electrically connected to the second confinement layer (600); In the thickness direction of the substrate (100), the first connecting wall (712) forms a first orthographic projection on the substrate (100), the second connecting wall (713) forms a second orthographic projection on the substrate (100), and the second orthographic projection covers the first orthographic projection.

9. The semiconductor laser of claim 8, wherein: The ridge waveguide layer (710) has a gradually increasing trend along a cross section perpendicular to a thickness direction of the substrate (100) along a direction close to the substrate (100).

10. A method of fabricating a semiconductor laser, the method comprising: Comprise, ​ A substrate is provided, and along the thickness direction of the substrate, a first confinement layer, a first waveguide layer, an active region, a second waveguide layer and a second confinement layer are sequentially stacked on one side of the substrate; A ridge waveguide layer is formed on the side of the second confinement layer away from the substrate, and along a direction perpendicular to the thickness direction of the substrate, at least one side of the ridge waveguide layer forms a first etching groove with the second confinement layer; A passivation layer is formed on the groove wall of the first etching groove; A conductive layer is formed on the side of the passivation layer away from the ridge waveguide layer and the second confinement layer; A first conductive member is formed on the side of the ridge waveguide layer away from the substrate, and a second conductive member is formed on the side of the substrate away from the first conductive member, and the first conductive member is electrically connected to the conductive layer.

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