Semiconductor laser and preparation method thereof

Abstract

The embodiment of the invention provides a semiconductor laser and a preparation method thereof. The semiconductor laser comprises a substrate, a first limiting layer, a first waveguide layer, an active region, a second waveguide layer and a second limiting layer, the ridge waveguide layer is formed on one side of the second limiting layer; the ridge waveguide layer and the second limiting layer form a first etching groove in the thickness direction perpendicular to the substrate; the passivation layer is formed on the groove wall of the first etching groove; a conductive layer formed on one side of the passivation layer; the first conductive part is formed on one side of the ridge waveguide layer, and the second conductive part is formed on one side, deviating from the first conductive part, of the substrate; the first conductive member electrically connects the conductive layer and the ridge waveguide layer. When the first conductive part and the second conductive part are connected with a power supply, an electric field can be formed in the conductive layer, so that carriers in the ridge waveguide layer can be far away from the side wall of the ridge waveguide layer, the carriers in the ridge waveguide layer are more concentrated, the injection efficiency of the carriers is further improved, a light field can be optimized, and the light beam quality of the semiconductor laser can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor lasers, and in particular to a semiconductor laser and a method for manufacturing the same. Background Art

[0002] Semiconductor lasers play an important role in optical communications, display lighting, laser processing, and other fields. However, traditional semiconductor lasers suffer from a current spreading effect—current diffusion during lateral transmission leads to uneven current density distribution in the active region, significantly increasing the threshold current and degrading the light field distribution, thus restricting the output performance of semiconductor lasers.

[0003] Traditional semiconductor lasers often adopt a ridge structure design, in which a ridge waveguide layer is formed through selective etching. The ridge waveguide layer can effectively realize concentrated current injection and light field mode control, 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 side walls 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 and affect the beam quality. Summary of the Invention

[0005] The embodiments of the present application provide a semiconductor laser and a method for preparing the same, which 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, an embodiment of the present application provides 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 a thickness direction;

[0008] a ridge waveguide layer formed on a side of the second confinement layer facing away from the substrate; a first etched groove is formed between at least one side of the ridge waveguide layer and the second confinement layer along a thickness direction perpendicular to the substrate;

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

[0010] A conductive layer is formed on a 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, wherein the first conductive member is formed on a side of the ridge waveguide layer facing away from the substrate, and the second conductive member is formed on a side of the substrate facing 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 conductive layer is made of at least one of indium tin oxide, indium gallium zinc oxide, and graphene.

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

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

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

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

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

[0018] In a possible implementation, the ridge waveguide layer has a first connecting wall and a second connecting wall positioned opposite to each other in a thickness direction, the first connecting wall is electrically connected to the first conductive member, and the second connecting wall is electrically connected to the second limiting 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 manner, along a direction approaching the substrate, a cross section of the ridge waveguide layer along a thickness direction perpendicular to the substrate tends to gradually increase.

[0021] In a second aspect, an embodiment of the present application provides a method for preparing 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 one side of the substrate along a thickness direction of the substrate;

[0023] forming a ridge waveguide layer on a side of the second confinement layer facing away from the substrate, wherein a first etched groove is formed between at least one side of the ridge waveguide layer and the second confinement layer along a thickness direction perpendicular to the substrate;

[0024] forming a passivation layer on the wall of the first etching groove;

[0025] forming a conductive layer on a side of the passivation layer away from the ridge waveguide layer and the second confinement layer;

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

[0027] A semiconductor laser and a method for manufacturing the same are provided in an embodiment of the present application. A conductive layer is formed on a side of a passivation layer facing away from the ridge waveguide layer and the second confinement layer. When the first conductive member and the second conductive member are connected to a power source, an electric field is generated in the conductive layer. Under the action of the electric field, carriers in the ridge waveguide layer near the sidewalls of the ridge waveguide layer can move toward the middle of the ridge waveguide layer along a thickness direction perpendicular to the substrate. This allows the carriers in the ridge waveguide layer to move away from the sidewalls of the ridge waveguide layer, forming a depletion layer at the sidewalls of the ridge waveguide layer. This prevents carriers in the ridge waveguide layer from being captured by defects at the sidewalls of the ridge waveguide layer, further concentrates the carriers in the ridge waveguide layer, and improves the efficiency of carrier injection from the ridge waveguide layer into the active region. This effectively reduces the threshold current of the semiconductor laser, reduces the loss of the semiconductor laser, optimizes the optical field, and further improves the beam quality of the semiconductor laser. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0030] Figure 2 Schematic diagram of growing a third waveguide layer on a second confinement layer provided in some embodiments of the present application;

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

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

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

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

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

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

[0037] Figure 9 A schematic diagram comparing the valence band variation at the sidewall of the ridge waveguide layer along the thickness direction perpendicular to the substrate provided in some embodiments of the present application with the valence band variation in the related art, wherein the solid line represents the valence band variation in some embodiments of the present application, and the dotted line represents the valence band variation in the related art;

[0038] Figure 10 A schematic diagram comparing the hole concentration variation in the ridge waveguide layer along the thickness direction perpendicular to the substrate provided in some embodiments of the present application with the hole concentration variation in the related art, wherein the solid line represents the hole concentration variation in some embodiments of the present application, and the dotted line represents the hole concentration variation in the related art;

[0039] Figure 11 This is a flow chart of a method for preparing a semiconductor laser provided in some embodiments of this application.

[0040] Reference numerals:

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

[0042] 200, first restriction layer;

[0043] 300, first waveguide layer;

[0044] 400, active area;

[0045] 500, second waveguide layer;

[0046] 600, second restriction layer;

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

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

[0049] 900. Conductive layer.

[0050] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0051] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0052] Semiconductor lasers play an important role in optical communications, display lighting, laser processing, and other fields. However, traditional semiconductor lasers suffer from a current spreading effect—current diffusion during lateral transmission leads to uneven current density distribution in the active region, significantly increasing the threshold current and degrading the light field distribution, thus restricting the output performance of semiconductor lasers.

[0053] Traditional semiconductor lasers often adopt a ridge structure design, in which a ridge waveguide layer is formed through selective etching. The ridge waveguide layer can effectively realize concentrated current injection and light field mode control, 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 side walls 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 and affect the beam quality.

[0055] The present application provides a semiconductor laser and a method for manufacturing the same. A conductive layer is formed on a side of a passivation layer facing away from a ridge waveguide layer and a second confinement layer. When the first conductive member and the second conductive member are connected to a power source, an electric field is generated in the conductive layer. Under the action of the electric field, carriers in the ridge waveguide layer near the sidewalls of the ridge waveguide layer can move toward the middle of the ridge waveguide layer along a thickness direction perpendicular to the substrate. This allows the carriers in the ridge waveguide layer to move away from the sidewalls of the ridge waveguide layer, forming a depletion layer at the sidewalls of the ridge waveguide layer. This prevents carriers in the ridge waveguide layer from being captured by defects at the sidewalls of the ridge waveguide layer, further concentrates the carriers in the ridge waveguide layer, and improves the efficiency of carrier injection from the ridge waveguide layer into the active region. This effectively reduces the threshold current of the semiconductor laser, reduces the loss of the semiconductor laser, optimizes the optical field, and further improves the beam quality of the semiconductor laser.

[0056] The following specific embodiments describe in detail the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0057] First, see Figure 8 As shown, an embodiment of the present application provides a semiconductor laser, which can be an FP laser (Fabry-Perot laser), a fiber Bragg grating laser or a distributed feedback laser, etc., without particular limitation. Exemplarily, the semiconductor laser of the embodiment of the present application is a gallium nitride-based blue-green laser.

[0058] The semiconductor laser according to an embodiment of the present application includes a substrate 100. The substrate 100 has a thickness direction X. A first confinement layer 200 is formed on one side of the substrate 100 along the thickness direction X. A first waveguide layer 300 is formed on a side of the first confinement layer 200 facing away from the substrate 100. An active region 400 is formed on a side of the first waveguide layer 300 facing away from the substrate 100. A second waveguide layer 500 is formed on a side of the active region 400 facing away from the substrate 100. A second confinement layer 600 is formed on a side of the second waveguide layer 500 facing away from the substrate 100. The active region 400 is a quantum well active region. In the semiconductor laser of the embodiment of the present application, the refractive index of the first confinement layer 200 is lower than that of the first waveguide layer 300, and the refractive index of the second confinement layer 600 is lower than that of the second waveguide layer 500. Therefore, in practical applications, the first confinement layer 200 and the second confinement layer 600 can confine the light beam to propagate within the first waveguide layer 300, the active region 400, and the second waveguide layer 500, thereby preventing the light beam from passing through the first confinement layer 200 or the second confinement layer 600.

[0059] Further, see Figure 3-Figure 7 As shown, a ridge waveguide layer 710 is formed on the side of the second confinement layer 600 facing away from the substrate 100. Along the thickness direction X perpendicular to the substrate 100, the width of the ridge waveguide layer 710 is smaller than the width of the second confinement layer 600, enabling the formation of a first etched groove 720 on at least one side of the ridge waveguide layer 710. The design of the ridge waveguide layer 710 can suppress the formed light field within the first waveguide layer 300, the active region 400, and the second waveguide layer 500, particularly near the active region 400, thereby improving the cohesion of the light field and enabling control of the light field, thereby enhancing the output performance of the semiconductor laser according to the present embodiment.

[0060] It is understood that the ridge waveguide layer 710 is formed through processes such as deposition and etching. Depending on the etching position, a first etched groove 720 can be formed on at least one side of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100. In other words, the number of first etched grooves 720 in the embodiment of the present application can be one or two. In the embodiment of the present application, during the process of etching the first etched groove 720 in the ridge waveguide layer 710, the first etched groove 720 is directly etched to the side of the second confinement layer 600 facing away from the substrate 100. Therefore, the first etched groove 720 is directly connected to the second confinement layer 600. More specifically, the groove wall of the first etched groove 720 is composed of the sidewall of the second confinement layer 600 facing away from the substrate 100 and the sidewall of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100.

[0061] Further, in the examples of this application, see Figure 5-Figure 8 As shown, a passivation layer 800 is formed on the wall of the first etched groove 720. The passivation layer 800 is an insulating dielectric layer. The passivation layer 800 can effectively isolate the outside air and water vapor, preventing the outside air and water vapor from contacting the second confinement layer 600, and preventing the outside air and water vapor from contacting the ridge waveguide layer 710. This can effectively ensure the stability of the second confinement layer 600 and the ridge waveguide layer 710, and improve the stability and quality of the output beam of the semiconductor laser. The refractive index of the passivation layer 800 in this embodiment of the application is lower than that of the ridge waveguide layer 710 to prevent the light beam from transmitting through the passivation layer 800 and escaping to the outside of the semiconductor laser, causing unnecessary loss.

[0062] Further, see Figure 8 As shown, a first conductive member 711 is formed on the side of the ridge waveguide layer 710 facing away from the substrate 100, and a second conductive member 110 is formed on the side of the substrate 100 facing away from the first conductive member 711. The first conductive member 711 can serve as an anode electrode, and the second conductive member 110 can serve as a cathode electrode. When the first conductive member 711 and the second conductive member 110 are connected to a power source, a current flows from the first conductive member 711 to the second conductive member 110 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. During this process, carriers 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 converge in the active region 400, thereby enabling the semiconductor laser of the present embodiment to generate and output a 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 a passivation layer 800 is formed on the groove wall of the first etched groove 720, when the first conductive member 711 and the second conductive member 110 are connected to a power source, the generated current will flow in the ridge waveguide layer 710 with a smaller width dimension toward the second conductive member 110. Under the restriction of the ridge waveguide layer 710, the current can be more concentrated, and the carriers can be more concentratedly injected into the active area 400, which can effectively improve the carrier injection efficiency and reduce the threshold current of the semiconductor laser.

[0064] During the process of forming the ridge waveguide layer 710 by etching, the etching process inevitably causes defects such as lattice damage and dangling bonds to appear on the sidewalls of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100. 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 and affect the quality of the light beam. More specifically, when the first conductive member 711 and the second conductive member 110 are connected to a power source, the carriers in the ridge waveguide layer 710 diffuse along the thickness direction X perpendicular to the substrate 100, so that the carriers in the ridge waveguide layer 710 are captured by the defects at the sidewalls of the ridge waveguide layer 710, causing the semiconductor laser to heat up, thereby increasing the loss of the semiconductor laser. Similarly, since the first etched groove 720 is directly connected to the sidewall of the second confinement layer 600 facing away from the substrate 100, defects such as lattice damage and dangling bonds may also appear on the sidewall of the second confinement layer 600 facing away from the substrate 100. These defects may 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 to a power source, carriers in the second confinement layer 600 and the second waveguide layer 500 may diffuse along the thickness direction X perpendicular to the substrate 100. As a result, the carriers in the second confinement layer 600 and the second waveguide layer 500 may be captured by defects on the sidewall of the second confinement layer 600, causing the semiconductor laser to heat up and increase the loss of the semiconductor laser.

[0065] In the examples of this application, see Figure 7 and Figure 8As shown, after the passivation layer 800 is formed on the groove wall of the first etched groove 720, the conductive layer 900 is formed on the side of the passivation layer 800 away from the ridge waveguide layer 710 and the second confinement layer 600. This is equivalent to forming the conductive layer 900 on the side of the passivation layer 800 away from the ridge waveguide layer 710 and the side of the passivation layer 800 away from the second confinement layer 600, and then forming the first conductive member 711 on the side of the ridge waveguide layer 710 away from the substrate 100. The first conductive member 711 is electrically connected not only to the ridge waveguide layer 710, but also to the conductive layer 900.

[0066] It should be noted that in the embodiment of the present application, due to the conductive properties of the conductive layer 900, its ability to isolate air and water vapor is poor. Therefore, a passivation layer 800 is formed between the conductive layer 900, the ridge waveguide layer 710, and the second confinement layer 600. Since the passivation layer 800 is an insulating dielectric layer, it has a good isolation effect, isolating air and water vapor, 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, resulting in 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, resulting in tunneling. Therefore, the passivation layer 800 can provide isolation and protection for the conductive layer 900 and the ridge waveguide layer 710, as well as the conductive layer 900 and the second confinement layer 600.

[0067] When the first conductive member 711 and the second conductive member 110 are connected to a power source, an electric field can be formed in the conductive layer 900. Along the thickness direction X perpendicular to the substrate 100, the carriers in the ridge waveguide layer 710 near the side wall of the ridge waveguide layer 710 can move toward the middle position of the ridge waveguide layer 710 under the action of the electric field, thereby enabling the carriers in the ridge waveguide layer 710 to move away from the side wall of the ridge waveguide layer 710, so that a depletion layer is formed at the side wall of the ridge waveguide layer 710, thereby preventing the carriers in the ridge waveguide layer 710 from being captured by defects at the side wall of the ridge waveguide layer 710.

[0068] Similarly, when an 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 that are close to the side wall of the second confinement layer 600 facing away from the substrate 100 can move toward the active area 400 under the action of the electric field, thereby enabling the carriers in the second confinement layer 600 to move away from the side wall of the second confinement layer 600, so that a depletion layer is formed at the side wall of the second confinement layer 600, thereby preventing the carriers in the second confinement layer 600 from being captured by defects at the side wall 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, since the carriers at the side walls of the ridge waveguide layer 710 move toward the middle position of the ridge waveguide layer 710, the carriers in the ridge waveguide layer 710 can be more concentrated, thereby improving the efficiency of injecting carriers in the ridge waveguide layer 710 into the active area 400, effectively reducing the threshold current of the semiconductor laser, reducing the loss of the semiconductor laser, and optimizing the light field, which can further improve the beam quality of the semiconductor laser.

[0070] Similarly, in the second confinement layer 600, along the thickness direction X of the substrate 100, since the carriers in the second confinement layer 600 and the second waveguide layer 500 move toward the active region 400, 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 can be avoided. This can make the carriers in the second confinement layer 600 and the second waveguide layer 500 more concentrated, thereby improving the efficiency of injecting the carriers in the second confinement layer 600 and the second waveguide layer 500 into the active region 400, effectively reducing the threshold current of the semiconductor laser, reducing the loss of the semiconductor laser, optimizing the optical field, and further improving the beam quality of the semiconductor laser.

[0071] In the examples of this application, see Figure 3-Figure 8 As shown, along the thickness direction X perpendicular to the substrate 100, first etched grooves 720 are formed on both sides of the ridge waveguide layer 710 by an etching process. That is, in the embodiment of the present application, there are two first etched grooves 720, and accordingly, a passivation layer 800 and a conductive layer 900 are formed at each first etched groove 720. In the embodiment of the present application, when the first conductive member 711 and the second conductive member 110 are connected to a 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 injecting carriers from the ridge waveguide layer 710 into the active region 400, effectively reducing the threshold current of the semiconductor laser, reducing the loss of the semiconductor laser, and optimizing the light field, which can further improve 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] For example, in the embodiment of the present application, the material of the conductive layer 900 is indium tin oxide. Since indium tin oxide is a highly 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 carriers toward 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, the second confinement layer 600, and the second waveguide layer 500 to be more concentratedly injected into the active area 400, thereby improving the carrier injection efficiency.

[0074] Furthermore, 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, achieving dual optimization of reducing the threshold current and increasing the output power of the semiconductor laser.

[0075] In some embodiments, the passivation layer 800 has a thickness dimension D, where 5 nm ≤ D ≤ 300 nm.

[0076] It can be understood that when the first conductive member 711 and the second conductive member 110 are connected to a power source, the electric field formed in the conductive layer 900 has a certain range. When the thickness of the passivation layer 800 is less than 5 nm, it will affect the effect of the passivation layer 800 in isolating air and water vapor, and the range of the electric field in the ridge waveguide layer 710 will be too large; when the thickness of the passivation layer 800 is greater than 300 nm, the range of the electric field in the ridge waveguide layer 710 and the second confinement layer 600 will be too small, and the carriers in the ridge waveguide layer 710 and the second confinement layer 600 will be closer to the defects at the side walls, and the carriers cannot be effectively prevented from being captured by the defects at the side walls 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 carriers in the first confinement layer 200 and the first waveguide layer 300 are holes; 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 carriers in the second waveguide layer 500, the second confinement layer 600 and the ridge waveguide layer 710 are electrons.

[0078] When the first conductive member 711 and the second conductive member 110 are connected to a power source, a current is generated 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. This causes holes in the ridge waveguide layer 710, the second confinement layer 600, and the second waveguide layer 500 to move toward the active region 400, and causes electrons in the first waveguide layer 300 and the first confinement layer 200 to move toward the active region 400. When the holes and electrons combine in the active region 400, the semiconductor laser according to the embodiment of the present application can 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, on the one hand, causes the holes at the sidewalls of the ridge waveguide layer 710 to move toward the middle position of the ridge waveguide layer 710, thereby making the holes in the ridge waveguide layer 710 more concentrated; on the other hand, it causes the holes at the sidewalls of the second confinement layer 600 to move toward the position of the active region 400, thereby making the holes in the second confinement layer 600 and the second waveguide layer 500 more concentrated. As a result, 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, thereby improving the efficiency of hole injection, 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.

[0080] Because holes in the ridge waveguide layer 710 are able to move away from defects on the sidewalls of the ridge waveguide layer 710 under the influence of the electric field, holes in the ridge waveguide layer 710 are prevented from being trapped by defects on the sidewalls of the ridge waveguide layer 710, thus avoiding unnecessary hole loss. This effectively maintains the hole concentration in the ridge waveguide layer 710 and reduces heating of the semiconductor laser. Similarly, because holes in the second confinement layer 600 and the second waveguide layer 500 are able to move away from defects on the sidewalls of the second confinement layer 600 under the influence of the electric field, holes in the second confinement layer 600 and the second waveguide layer 500 are prevented from being trapped by defects on the sidewalls of the second confinement layer 600, thus avoiding unnecessary hole loss. This effectively maintains the hole concentration in the second confinement layer 600 and the second waveguide layer 500 and reduces heating of the semiconductor laser.

[0081] In some embodiments, the conductive layer 900 may or may not be doped. 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 contact 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, resulting in tunneling. Therefore, it is necessary to isolate the conductive layer 900 and the ridge waveguide layer 710, as well as between the conductive layer 900 and the second confinement layer 600, through the passivation layer 800.

[0083] In the embodiment of the present application, when the first conductive member 711 and the second conductive member 110 are connected to 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. Figure 9 As shown, in the embodiment of the present application, in terms of the lateral distance of the ridge waveguide layer 710, by optimizing the valence band of the sidewall of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100, it is possible to effectively prevent the holes in the ridge waveguide layer 710 from moving toward the defects in the sidewall of the ridge waveguide layer 710. Similarly, by optimizing the valence band of the sidewall of the second confinement layer 600 facing away from the substrate 100, it is possible to effectively prevent the holes in the second confinement layer 600 and the second waveguide layer 500 from moving toward the defects in the sidewall of the second confinement layer 600. Figure 10 As shown, in the lateral distance of the ridge waveguide layer 710, due to the action of the electric field of the conductive layer 900, along the thickness direction X perpendicular to the substrate 100, the concentration of holes in the ridge waveguide layer 710, the second confinement layer 600, and the second waveguide layer 500 is low on both sides and high in the middle. This also shows that the holes in the ridge waveguide layer 710, the second confinement layer 600, and the second waveguide layer 500 are more concentrated, thereby improving the efficiency of hole injection into the active region 400, 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.

[0084] In some embodiments, along the thickness direction X of the substrate 100 , the ridge waveguide layer 710 has a thickness dimension H, where 100 nm≦H≦500 nm.

[0085] In some embodiments, see Figure 3-Figure 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 that are positioned opposite to each other, wherein the first connecting wall 712 is farther away from the substrate 100 than the second connecting wall 713, the first connecting wall 712 is electrically connected to the first conductive member 711, and the second connecting wall 713 is electrically connected to the second limiting layer 600.

[0086] Furthermore, along the thickness direction X of the substrate 100 , the first connecting wall 712 of the embodiment of the present application 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 can be understood that the embodiment of the present application completely covers the first orthographic projection by designing the second orthographic projection, that is, the area of ​​the second connecting wall 713 is not less than the area of ​​the first connecting wall 712. In more detail, 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 example, see 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-section of the ridge waveguide layer 710 is a square. Figure 3 and Figure 5-Figure 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-section of the ridge waveguide layer 710 is a trapezoid.

[0088] In some embodiments, see Figure 3 and Figure 5-Figure 8 As shown, along the direction approaching the substrate 100, the cross-section of the ridge waveguide layer 710 along the thickness direction X perpendicular to the substrate 100 tends to gradually increase. That is, the area of ​​the first connecting wall 712 is smaller than the area of ​​the second connecting wall 713, thereby making the cross-section of the ridge waveguide layer 710 trapezoidal in shape. As a result, along the thickness direction X perpendicular to the substrate 100, at least one sidewall of the ridge waveguide layer 710 forms a certain inclination angle with the second confinement layer 600, making it easier to form the ridge waveguide layer 710 through an etching process, and also making it easier to form the passivation layer 800 on the sidewall of the ridge waveguide layer 710.

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

[0090] Along the thickness direction X perpendicular to the substrate 100, since both sidewalls of the ridge waveguide layer 710 and the second confinement layer 600 form a certain inclination angle, it is convenient to form the ridge waveguide layer 710 through an 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 facing away from the ridge waveguide layer 710 also forms a certain inclination angle with the second confinement layer 600, which facilitates the formation of the conductive layer 900 on the side of the passivation layer 800 facing away from the ridge waveguide layer 710.

[0091] Second, see Figure 11As shown, an embodiment of the present application provides a method for preparing a semiconductor laser, which is used to prepare the above-mentioned semiconductor laser.

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

[0093] Step S100: 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 one side of the substrate along a thickness direction of the substrate;

[0094] In this step, the substrate 100 is placed in the growth chamber of the MOCVD equipment. Figure 1 As shown, along the thickness direction X of the substrate 100, 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, thereby obtaining the epitaxial structure of the semiconductor laser according to the embodiment of the present application.

[0095] Furthermore, during 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 doped with P-type, and the first waveguide layer 300 and the first confinement layer 200 are doped with N-type.

[0096] Step S200: forming a ridge waveguide layer on a side of the second confinement layer facing away from the substrate, and forming a first etched groove between at least one side of the ridge waveguide layer and the second confinement layer along a thickness direction perpendicular to the substrate;

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

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

[0099] Step S300, forming a passivation layer on the wall of the first etched groove;

[0100] In this step, see Figure 5As shown, a passivation layer 800 is deposited on the sidewalls of the two first etched grooves 720 . During this process, a passivation layer 800 is also deposited on the first connecting wall 712 of the ridge waveguide layer 710 .

[0101] Step S400, forming a conductive layer on a side of the passivation layer away from the ridge waveguide layer and the second confinement layer;

[0102] In this step, see Figure 6 As shown, the passivation layer 800 in each first etched groove 720 is etched to form a second etched groove 810 on the corresponding passivation layer 800. Specifically, the second etched 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. Figure 7 As shown, a conductive layer 900 is deposited on the wall of the second etched groove 810 .

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

[0104] Step S500: forming a first conductive member on a side of the ridge waveguide layer facing away from the substrate, and forming a second conductive member on a side of the substrate facing away from the first conductive member, wherein the first conductive member is electrically connected to the conductive layer;

[0105] In this step, see Figure 8 As shown, the passivation layer 800 on the first connecting wall 712 is firstly removed by an etching process to expose the first connecting wall 712, and 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 those skilled in the art will readily identify other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The present invention is not limited to the precise structure described above and illustrated in the accompanying drawings, and various modifications and variations may be made without departing from the scope thereof. The scope of the present invention is limited solely by the appended claims.

Claims

1. A semiconductor laser, characterized in that include: 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 a thickness direction; A ridge waveguide layer (710) is formed on a side of the second confinement layer (600) facing away from the substrate (100); along a thickness direction perpendicular to the substrate (100), at least one side of the ridge waveguide layer (710) and the second confinement layer (600) form a first etched groove (720); a passivation layer (800) formed on the wall of the first etching groove (720); a conductive layer (900) formed on a side of the passivation layer (800) facing away from the ridge waveguide layer (710) and the second confinement layer (600); A first conductive member (711) and a second conductive member (110), wherein the first conductive member (711) is formed on a side of the ridge waveguide layer (710) facing away from the substrate (100), and the second conductive member (110) is formed on a side of the substrate (100) facing away from the first conductive member (711); the first conductive member (711) electrically connects the conductive layer (900) and the ridge waveguide layer (710).

2. The semiconductor laser according to 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 according to claim 1, wherein: The passivation layer (800) is an insulating dielectric layer.

4. The semiconductor laser according to any one of claims 1 to 3, characterized in that: A second etching groove (810) is formed on the side of the passivation layer (800) away from the ridge waveguide layer (710) and the second limiting layer (600), and the conductive layer (900) is formed on the groove wall of the second etching groove (810).

5. The semiconductor laser according to claim 4, wherein: The passivation layer (800) has a thickness dimension D, wherein 5 nm ≤ D ≤ 300 nm.

6. The semiconductor laser according to any one of claims 1 to 3 and 5, characterized in that: 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 according to any one of claims 1 to 3 and 5, characterized in that: Along the thickness direction of the substrate (100), the thickness dimension of the ridge waveguide layer (710) is H, wherein 100 nm ≤ H ≤ 500 nm.

8. The semiconductor laser according to any one of claims 1 to 3 and 5, characterized in that: The ridge waveguide layer (710) has a first connecting wall (712) and a second connecting wall (713) that are positioned opposite to each other along the thickness direction, the first connecting wall (712) is electrically connected to the first conductive member (711), and the second connecting wall (713) is electrically connected to the second limiting layer (600); Along the thickness direction of the substrate (100), the first connecting wall (712) forms a first orthographic projection on the substrate (100), and the second connecting wall (713) forms a second orthographic projection on the substrate (100), wherein the second orthographic projection covers the first orthographic projection.

9. The semiconductor laser according to claim 8, wherein: Along the direction approaching the substrate (100), the cross section of the ridge waveguide layer (710) along the thickness direction perpendicular to the substrate (100) tends to gradually increase.

10. A method for preparing a semiconductor laser, characterized in that: include, 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 one side of the substrate along a thickness direction of the substrate; forming a ridge waveguide layer on a side of the second confinement layer facing away from the substrate, wherein a first etched groove is formed between at least one side of the ridge waveguide layer and the second confinement layer along a thickness direction perpendicular to the substrate; forming a passivation layer on the wall of the first etching groove; forming a conductive layer on a side of the passivation layer away from the ridge waveguide layer and the second confinement layer; A first conductive member is formed on a side of the ridge waveguide layer facing away from the substrate, and a second conductive member is formed on a side of the substrate facing away from the first conductive member. The first conductive member is electrically connected to the conductive layer.

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