Semiconductor laser chip structure and manufacturing method thereof

Abstract

The invention relates to the technical field of semiconductor laser manufacturing. The invention particularly relates to a semiconductor laser chip structure and a manufacturing method thereof. The semiconductor laser chip structure provided by the invention comprises a laser substrate and a heavily doped table, and the heavily doped table is arranged on the surface of one side, opposite to a substrate layer, of an upper limiting layer of the laser substrate and comprises a first ohmic contact layer, a second ohmic contact layer and a resistance control layer; the heavily doped table is provided with a current injection region, and is provided with a first current injection window and a second current injection window; a current path from the first current injection window to the substrate layer does not pass through the resistance control layer, and a current path from the second current injection window to the substrate layer passes through the resistance control layer; the second current injection window is at least arranged on one side of the current injection region close to the rear cavity surface. According to the semiconductor laser chip structure provided by the invention, carrier injection of the front cavity surface and the rear cavity surface can be effectively balanced, so that local failure of the front cavity surface is avoided, and the device efficiency can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor laser chips, and more particularly to a semiconductor laser chip structure and a manufacturing method thereof. Background Art

[0002] Semiconductor lasers are widely used in fields including industrial production, lidar, military attack and defense, optical communications, optical information storage, and medical cosmetology due to their compact structure, long life, high reliability, high electro-optical conversion efficiency, fast modulation rate, wide wavelength range, and easy integration. With the development and progress of society, higher requirements are placed on the efficiency and reliability of semiconductor lasers in many application fields. For example, in the industrial application of 10,000-watt-class fiber semiconductor lasers, for the 915 / 976nm semiconductor lasers used for optical pumping, the application end requires semiconductor laser devices with higher power, higher electro-optical conversion efficiency, and better reliability.

[0003] Generally speaking, the chip structure of high-power fiber semiconductor lasers used in the industrial field, such as the chip structure of 10,000-watt fiber semiconductor lasers, needs to be coated with a composite reflective film with a reflectivity of less than 5% on the front cavity surface, and a composite reflective film with a reflectivity of more than 95% on the back cavity surface, in order to obtain high-power laser power output. Therefore, the optical power density on the front cavity side will be much higher than that on the back cavity side. This leads to different temperatures on the front cavity side and the back cavity side of the semiconductor laser chip structure, which makes the front cavity surface more prone to local failure and reduces the electro-optical conversion efficiency. Therefore, a solution is needed to solve the problem that the front cavity surface of the semiconductor laser chip structure used in high-power fiber lasers is more prone to local failure and reduced electro-optical conversion efficiency. Summary of the invention

[0004] Therefore, the present application provides a semiconductor laser chip structure and a manufacturing method thereof to solve the problem that the front cavity surface of the semiconductor laser chip structure for high-power fiber lasers is prone to local failure and reduced electro-optical conversion efficiency.

[0005] In one aspect of the present application: the present application provides a semiconductor laser chip structure, the semiconductor laser chip structure comprises: a laser substrate, the laser substrate comprises: a substrate layer, a buffer layer, a lower confinement layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer and an upper confinement layer which are stacked in sequence; a heavily doped stage, which is arranged on the surface of the upper confinement layer of the laser substrate which faces away from the substrate layer, and comprises a first ohmic contact layer, a second ohmic contact layer and a resistance control layer; the resistance control layer is arranged between the first ohmic contact layer and the second ohmic contact layer, and the resistance value is respectively greater than the resistance value of the first ohmic contact layer and the resistance value of the second ohmic contact layer; the heavily doped stage is divided into a current injection area, and a first current injection window and a second current injection window are arranged in the current injection area; wherein the current path from the first current injection window to the substrate layer does not pass through the resistance control layer, and the current path from the second current injection window to the substrate layer passes through the resistance control layer; the semiconductor laser chip structure has a front cavity surface and a rear cavity surface which are opposite in the length direction of the laser substrate; the second current injection window is arranged at least on the side of the current injection area close to the rear cavity surface.

[0006] The semiconductor laser chip structure provided by the present application changes the conventional single-layer structure into a double-layer ohmic contact layer sandwiched with a resistance control layer in the ohmic contact layer on the upper limiting layer. The resistance value of the resistance control layer is respectively greater than the ohmic contact layers on the upper and lower sides. The second current injection window is provided with a first current injection window, so that the second current injection window needs to pass through the resistance control layer because the current path needs to pass through the resistance control layer. The resistance control layer has a relatively high resistance value, which can suppress the current injection in the area where the second current injection window is located. Therefore, the second current injection window is provided at least on one side of the rear cavity surface, which can suppress the carrier injection near the rear cavity surface. At the same time, the first current injection window can meet the conventional current injection requirements, and the carriers are not suppressed from conventional injection. Through the different settings of the first current injection window and the second current injection window, the carrier injection conditions in different regions are balanced, so that the carrier injection balance of the front and rear cavity surfaces of the semiconductor laser can be achieved, thereby ensuring that the temperature rise of the front and rear cavity surfaces is basically the same, thereby avoiding the problem of local failure of the front cavity surface, improving the reliability of the semiconductor laser; and improving the electro-optical conversion efficiency of the semiconductor laser. In addition, when the semiconductor laser is flipped face down on a heat sink, the quantum well active layer in the second current injection window area is closer to the solder and the heat sink, the heat dissipation path is shorter, and the higher temperature generated on the front cavity surface is more easily conducted away through the heat sink, making the heat distribution on the front and rear cavity surfaces more balanced, which can effectively suppress the thermal lens effect, thereby reducing the far-field horizontal divergence angle to a certain extent and improving the device performance and reliability.

[0007] Optionally, in some embodiments of the present application, the bottom of the first current injection window is located in the first ohmic contact layer close to the upper confinement layer, and the bottom of the second current injection window is located in the second ohmic contact layer away from the upper confinement layer.

[0008] In the semiconductor laser chip structure provided by the present application, the bottoms of the first current injection window and the second current injection window are respectively located in the corresponding ohmic contact layers, so that after the P-side electrode is subsequently formed, a good ohmic contact can be formed with the P-side electrode, which is beneficial to the transmission of carriers and thus improves the device performance.

[0009] Optionally, the doping concentration of the resistance control layer is less than the doping concentration of the first ohmic contact layer and the doping concentration of the second ohmic contact layer; and / or the thickness of the resistance control layer is less than or equal to the thickness of the first ohmic contact layer and the thickness of the second ohmic contact layer.

[0010] The semiconductor laser chip structure provided by the present application can suppress carriers at the position with the resistance control layer, thereby balancing the carrier injection conditions of the front and rear cavity surfaces, because the doping concentration and / or thickness of the resistance control layer is smaller than the ohmic contact layers on both sides.

[0011] Optionally, in some embodiments of the present application, the doping concentration of the first ohmic contact layer is 2E19cm -3 ~1E20cm -3 ; The doping concentration of the second ohmic contact layer is 2E19cm -3 ~1E20cm -3 ; The doping concentration for resistance control is 1E17cm -3 ~1E20cm -3 ; The thickness of the first ohmic contact layer is 200nm~800nm; The thickness of the second ohmic contact layer is 200nm~800nm; The thickness of the resistance control layer is 200nm~500nm; The distance between the bottom of the first current injection window and the bottom of the first ohmic contact layer is 200nm~500nm; The distance between the bottom of the second current injection window and the bottom of the second ohmic contact layer is 200nm~500nm.

[0012] Optionally, in some embodiments of the present application, part of the first ohmic contact layer, the resistance control layer and the second ohmic contact layer in the current injection region form a number of spaced heavily doped islands, and the heavily doped islands constitute a second current injection window; the first current injection window surrounds the second current injection window.

[0013] Optionally, in some embodiments of the present application, a plurality of second current injection windows are spaced apart along the direction from the back cavity surface to the front cavity surface of the semiconductor laser, and the spacing between adjacent second current injection windows gradually increases in the direction from the back cavity surface to the front cavity surface.

[0014] The semiconductor laser chip structure provided by the present application can make the first current injection window occupy a larger area through a plurality of second current injection windows arranged at intervals, thereby ensuring as much current injection as possible. At the same time, the interval distribution of the second current injection windows gradually increases from the rear cavity surface to the front cavity surface, so that the closer to the rear cavity surface, the higher the degree of carrier injection suppression, and the closer to the front cavity surface, the lower the degree of suppression, thereby balancing the carrier injection conditions of the front and rear cavity surfaces.

[0015] Optionally, in some embodiments of the present application, the width of the second current injection window is 10 μm to 100 μm; the distance between the second current injection window and the side boundary of the current injection zone is 5 μm to 10 μm; the distance between the second current injection window closest to the rear cavity surface and the boundary of the current injection zone close to the rear cavity surface is 5 μm to 10 μm; the distance between the edge of the second current injection window closest to the rear cavity surface close to the rear cavity surface and the edge of the second current injection window closest to the front cavity surface close to the front cavity surface, and the ratio of the total size of the current injection zone in the direction from the front cavity surface to the rear cavity surface is 1:1 to 1:5; in the direction from the rear cavity surface to the front cavity surface, the spacing between adjacent second current injection windows is S1, S2...S n , S n-1 :S n The ratio is 1:1~1:10, and S1 is 10μm~200μm.

[0016] Optionally, in some embodiments of the present application, the semiconductor laser provided by the present application further includes: a first isolation groove, located on the heavily doped stage, on both sides of the current injection zone; the bottom of the first isolation groove penetrates deep into the upper limiting layer; an insulating isolation layer, the insulating isolation layer covers the surface of the heavily doped stage outside the current injection zone that is opposite to the substrate layer and the surface of the laser substrate exposed on the side opposite to the substrate layer; a P-side electrode, the P-side electrode covers the surface of the current injection zone that is opposite to the substrate layer and the surface of the insulating isolation layer that is opposite to the substrate layer; an N-side electrode, the N-side electrode covers the surface of the substrate layer that is opposite to the upper limiting layer; the top-view projection area of ​​the heavily doped stage on the laser substrate is smaller than the area of ​​the laser substrate; the laser substrate has exposed platforms around the heavily doped stage; or, the top-view projection area of ​​the heavily doped stage on the laser substrate is equal to the area of ​​the laser substrate; the heavily doped stage is provided with non-current injection limiting grooves on the front cavity surface and the back cavity surface, respectively; the non-current injection limiting grooves are spaced apart from the current injection zone.

[0017] In another aspect of the present application, the present application provides a method for manufacturing a semiconductor laser chip structure, comprising the following steps: forming a laser substrate, the laser substrate comprising: a substrate layer, a buffer layer, a lower confinement layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer and an upper confinement layer stacked in sequence; forming a heavily doped platform, the heavily doped platform being formed on the surface of the upper confinement layer of the laser substrate facing away from the substrate layer, and comprising a first ohmic contact layer, a second ohmic contact layer and a resistance control layer; the resistance control layer being arranged between the first ohmic contact layer and the second ohmic contact layer, and having a resistance value greater than the resistance value of the first ohmic contact layer and the resistance value of the second ohmic contact layer, respectively; forming a current injection region in the heavily doped platform; forming a first current injection window and a second current injection window in the current injection region; wherein a current path from the first current injection window to the substrate layer does not pass through the resistance control layer, and a current path from the second current injection window to the substrate layer passes through the resistance control layer; the semiconductor laser chip structure has a front cavity surface and a rear cavity surface opposite to each other in the length direction of the laser substrate; the second current injection window is formed at least on one side of the current injection region close to the rear cavity surface.

[0018] The manufacturing method of the semiconductor laser chip structure provided in the present application can manufacture the semiconductor laser chip structure provided in the present application. The laser chip structure manufactured by the manufacturing method of the semiconductor laser chip structure provided in the present application, in the ohmic contact layer on the upper limiting layer, changes the conventional single-layer structure into a double-layer ohmic contact layer sandwiched with a resistance control layer, and the resistance value of the resistance control layer is respectively greater than the ohmic contact layers on the upper and lower sides, and cooperates with the setting of the first current injection window and the second current injection window, so that the second current injection window needs to pass through the resistance control layer because the current path needs to pass through the resistance control layer, and the resistance control layer has a relatively high resistance value, which can suppress the current injection in the area where the second current injection window is located. Therefore, the second current injection window is set at least on one side of the back cavity surface, which can suppress the injection of carriers near the back cavity surface. At the same time, the first current injection window can meet the conventional current injection requirements, and the carriers are not suppressed from conventional injection. By setting the first current injection window and the second current injection window differently, the carrier injection conditions in different regions are balanced, so that the carrier injection balance of the front and rear cavity surfaces of the semiconductor laser can be achieved, thereby ensuring that the temperature rise of the front and rear cavity surfaces is basically the same, thereby avoiding the problem of local failure of the front cavity surface, improving the reliability of the semiconductor laser; and improving the electro-optical conversion efficiency of the semiconductor laser. In addition, when the semiconductor laser P face down is flipped on the heat sink for use, because the quantum well active layer in the second current injection window area is closer to the solder and the heat sink, the heat dissipation path is shorter, and the higher temperature generated by the front cavity surface is easier to be conducted away through the heat sink, making the heat distribution at the front and rear cavity surfaces more balanced, which can effectively suppress the thermal lens effect, thereby reducing the far-field horizontal divergence angle to a certain extent, and improving the device performance and reliability.

[0019] Optionally, in some embodiments of the present application, in the step of forming a first current injection window and a second current injection window, the heavily doped platform is processed by etching, wherein the etching end point of the first current injection window is located in the first ohmic contact layer close to the upper limit layer, and the etching end point of the second current injection window is located in the second ohmic contact layer away from the upper limit.

[0020] Optionally, in some embodiments of the present application, in the step of forming a first current injection window and a second current injection window in the current injection area, part of the first ohmic contact layer, the resistance control layer and the second ohmic contact layer in the current injection area are etched to form a number of spaced heavily doped islands, and the heavily doped islands constitute the second current injection window; the first current injection window surrounds the second current injection window. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is the light field intensity distribution diagram of the semiconductor laser chip along the front and rear cavity surfaces; Figure 2 A schematic diagram of the basic structure of the semiconductor laser of this application; Figure 3a A schematic diagram of a first current injection window of a semiconductor laser of the present application; Figure 3b A schematic diagram of a second current injection window of the semiconductor laser of the present application; Figure 4 A top view of the basic structure of a semiconductor laser according to an embodiment of the present application; Figure 5 A top view of the basic structure of a semiconductor laser according to another embodiment of the present application; Figure 6 for Figure 5 Schematic diagram of the cross-sectional structure of the mm cross-sectional line from the side edge of the semiconductor laser to the nn cut-off line in the structure; Figure 7 A top view of the basic structure of a semiconductor laser according to another embodiment of the present application; Figure 8 for Figure 7 Schematic diagram of the cross-sectional structure of the mm cross-sectional line from the side edge of the semiconductor laser to the nn cut-off line in the structure. DETAILED DESCRIPTION

[0023] refer to Figure 1 , Figure 1 This is a light field intensity distribution diagram of a semiconductor laser chip for a high-power fiber laser along the front and rear cavity surfaces. The arrow direction in the figure is the direction from the rear cavity surface to the front cavity surface. The horizontal coordinate axis X-axis in the figure is the length direction of the semiconductor laser chip structure, the 0 point in the X-axis direction is the front cavity surface side, and the maximum value point is the rear cavity surface side; the Y-axis is the horizontal direction perpendicular to the X-axis. The vertical coordinate axis is the normalized data of the light field intensity, with a set value of 1, and the remaining values ​​are proportional values ​​compared with the set value. In actual use, this semiconductor laser chip structure is set in the laser cavity, the length direction of the semiconductor laser chip structure is consistent with the length direction of the cavity, the end face of the semiconductor laser chip structure facing the front of the cavity is the front cavity surface, and the end face facing the rear of the cavity is the rear end face. As can be seen from the figure, in terms of light field intensity distribution, the peak surface of the front cavity surface is significantly higher than the peak surface of the rear cavity surface, so the optical power density of the front cavity surface will be much higher than that of the rear cavity surface. Since the injection current density of the front and rear cavity surfaces is basically the same in the current injection area, however, due to the extremely asymmetric distribution of the optical power density of the front and rear cavity surfaces, it often means that the carrier consumption rate in the front cavity surface area is fast, and the carrier consumption rate in the rear cavity surface area is slow. This leads to, on the one hand, that the temperature rise of the front cavity surface will be greater than that of the rear cavity surface, and the uneven temperature distribution will become the starting point of the failure of the two failure modes of COMD (Catastrophic Optical Mirror Damage) and COBD (Catastrophic Optical Bulk Damage) in the local area of ​​the front cavity surface, greatly damaging the reliability of the semiconductor laser. On the other hand, the speed at which the rear cavity surface consumes carriers to achieve radiative recombination to form laser output is slow, and the extra carriers will leak to the non-current injection area, or in the form of non-radiative recombination such as spontaneous radiation and injection into deep energy level defect recombination centers, reducing the electro-optical conversion efficiency of the semiconductor laser.

[0024] Therefore, the present application provides a semiconductor laser chip structure and a manufacturing method thereof to solve the problem that the front cavity surface of the semiconductor laser chip used in high-power fiber lasers is prone to local failure and reduced electro-optical conversion efficiency.

[0025] The present application provides a semiconductor laser chip structure, comprising: a laser substrate, the laser substrate comprising: a substrate layer, a buffer layer, a lower confinement layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer and an upper confinement layer which are stacked in sequence; a heavily doped stage, which is arranged on the surface of the upper confinement layer of the laser substrate which is not facing the substrate layer, and comprises a first ohmic contact layer, a second ohmic contact layer and a resistance control layer; the resistance control layer is arranged between the first ohmic contact layer and the second ohmic contact layer, and the resistance value of the resistance control layer is respectively greater than the resistance value of the first ohmic contact layer and the resistance value of the second ohmic contact layer; the heavily doped stage is divided into a current injection area, and a first current injection window and a second current injection window are arranged in the current injection area; wherein the current path from the first current injection window to the substrate layer does not pass through the resistance control layer, and the current path from the second current injection window to the substrate layer passes through the resistance control layer; the second current injection window is arranged at least on the side of the current injection area close to the back cavity surface.

[0026] The present application also provides a method for manufacturing a semiconductor laser chip structure, comprising the following steps: forming a laser matrix, the laser matrix comprising: a substrate layer, a buffer layer, a lower confinement layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer and an upper confinement layer stacked in sequence; forming a heavily doped platform, the heavily doped platform being formed on the surface of the upper confinement layer of the laser matrix on the side facing away from the substrate layer, and comprising a first ohmic contact layer, a second ohmic contact layer and a resistance control layer; the resistance control layer being arranged between the first ohmic contact layer and the second ohmic contact layer, and having a resistance value greater than the resistance value of the first ohmic contact layer and the resistance value of the second ohmic contact layer, respectively; forming a current injection region in the heavily doped platform; forming a first current injection window and a second current injection window in the current injection region; wherein a current path from the first current injection window to the substrate layer does not pass through the resistance control layer, and a current path from the second current injection window to the substrate layer passes through the resistance control layer.

[0027] The semiconductor laser chip structure provided in the present application can effectively balance the carrier injection of the front and rear cavity surfaces, thereby balancing the temperature rise of the front and rear cavity surfaces, thereby avoiding local failure of the front cavity surface and improving device efficiency.

[0028] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. In the description of the present application, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0029] Example 1 refer to Figure 2-Figure 4In the figure, the X direction is the direction from the front cavity surface to the back cavity surface of the semiconductor laser chip, and the Y direction is the direction horizontally perpendicular to the X direction, that is, the lateral direction of the semiconductor laser chip. This embodiment provides a semiconductor laser chip structure, such as Figure 2 As shown, the semiconductor laser chip structure includes: The laser substrate 1 comprises: a substrate layer 11, a buffer layer 12, a lower confinement layer 13, a lower waveguide layer 14, a quantum well active layer 15, an upper waveguide layer 16 and an upper confinement layer 17 which are stacked in sequence; The heavily doped stage 2 is arranged on the surface of the upper limiting layer 17 of the laser substrate 1 on the side facing away from the substrate layer 11, and includes a first ohmic contact layer 21, a second ohmic contact layer 23 and a resistance control layer 22; the resistance control layer 22 is arranged between the first ohmic contact layer 21 and the second ohmic contact layer 23, and the resistance value of the resistance control layer 22 is respectively greater than the resistance value of the first ohmic contact layer 21 and the resistance value of the second ohmic contact layer 23; like Figure 4 As shown, the heavily doped stage 2 is divided into a current injection region Ia, and a first current injection window Iw is provided in the current injection region Ia. a and the second current injection window Iw b ; The current injection area Ia is used for current injection in practical applications; Among them, reference Figure 3a and Figure 3b , the first current injection window Iw a The current path to the substrate layer 11 does not pass through the resistance control layer 22, and the second current injection window Iw b The current path to the substrate layer 11 passes through the resistance control layer 22; the semiconductor laser chip structure has a front cavity surface and a rear cavity surface opposite to each other in the length direction of the laser substrate 1; the second current injection window Iw b At least it is arranged on the side of the current injection region Ia close to the rear cavity surface.

[0030] In actual use, the semiconductor laser chip structure provided in this embodiment is arranged in a laser cavity, the length direction of the semiconductor laser chip structure is consistent with the length direction of the cavity, the end face of the semiconductor laser chip structure facing the front of the cavity is the front cavity face, and the end face facing the rear of the cavity is the rear end face.

[0031] The semiconductor laser chip structure provided in this embodiment has an ohmic contact layer on the upper limiting layer 17, which changes the conventional single-layer structure into a double-layer ohmic contact layer sandwiching a resistance control layer 22. The resistance value of the resistance control layer 22 is respectively greater than the ohmic contact layers on the upper and lower sides, and cooperates with the first current injection window Iw a and the second current injection window Iw b The setting makes the second current injection window Iw bSince the current path needs to pass through the resistance control layer 22, the resistance control layer 22 has a relatively high resistance value, which can suppress the second current injection window Iw. b Therefore, the second current is injected into the window Iw b At least one side of the back cavity surface is set to suppress the carrier injection near the back cavity surface. a It can meet the conventional current injection requirements, and the carriers are not suppressed from conventional injection. a and the second current injection window Iw b Different settings can be used to balance the carrier injection conditions in different regions, so that the carrier injection balance of the front and rear cavity surfaces of the semiconductor laser can be achieved, thereby ensuring that the temperature rise of the front and rear cavity surfaces is basically the same, thereby avoiding the problem of local failure of the front cavity surface, and improving the reliability of the semiconductor laser; and avoiding the slow speed of the rear cavity surface consuming carriers to achieve radiation recombination to form laser output, and the extra carriers will leak to the non-current injection area, or in non-radiative recombination methods such as spontaneous radiation and injection into deep energy level defect recombination centers, thereby reducing the electro-optical conversion efficiency of the semiconductor laser, thereby improving the electro-optical conversion efficiency of the semiconductor laser. In addition, when the semiconductor laser P face-down is flipped on the heat sink for use, because the quantum well active layer 15 in the second current injection window area is closer to the solder and the heat sink, the heat dissipation path is shorter, and the higher temperature generated by the front cavity surface is more easily conducted away through the heat sink, making the heat distribution at the front and rear cavity surfaces more balanced, which can effectively suppress the thermal lens effect, thereby reducing the far-field horizontal divergence angle to a certain extent, and improving the device performance and reliability.

[0032] For further reference, Figure 3a and Figure 3b In some embodiments of the present application, the first current injection window Iw a The bottom of the second current injection window Iw is located in the first ohmic contact layer 21 close to the upper confinement layer 17. b The bottom of is located in the second ohmic contact layer 23 away from the upper limit.

[0033] The semiconductor laser chip structure provided in this embodiment has a first current injection window Iw a and the second current injection window Iw b The bottom of each is located in the corresponding ohmic contact layer, so that after the P-side electrode is subsequently formed, a good ohmic contact can be formed with the P-side electrode, which is beneficial to the transmission of carriers and thus improves the device performance.

[0034] Furthermore, the doping concentration of the resistance control layer 22 is less than the doping concentration of the first ohmic contact layer 21 and the doping concentration of the second ohmic contact layer 23; and / or, the thickness of the resistance control layer 22 is less than or equal to the thickness of the first ohmic contact layer 21 and the thickness of the second ohmic contact layer 23.

[0035] The semiconductor laser chip structure provided in this embodiment can suppress carriers at the position with the resistance control layer 22, thereby balancing the carrier injection conditions of the front and rear cavity surfaces, because the doping concentration and / or thickness of the resistance control layer 22 is smaller than the ohmic contact layers on both sides.

[0036] Specifically, in different implementations of the present application: The doping concentration of the first ohmic contact layer 21 is 2E19 cm -3 ~1E20cm -3 .

[0037] The doping concentration of the second ohmic contact layer 23 is 2E19 cm -3 ~1E20cm -3 .

[0038] The doping concentration for resistor control is 1E17cm -3 ~1E20cm -3 .

[0039] The thickness of the first ohmic contact layer 21 is 200 nm to 800 nm.

[0040] The thickness of the second ohmic contact layer 23 is 200 nm to 800 nm.

[0041] The thickness of the resistance control layer 22 is 200 nm to 500 nm.

[0042] The first current injection window Iw a The distance between the bottom of and the bottom of the first ohmic contact layer 21 is 200nm~500nm.

[0043] The second current injection window Iw b The distance between the bottom of and the bottom of the second ohmic contact layer 23 is 200nm~500nm.

[0044] Furthermore, in order to further balance the carrier injection of the front and rear cavity surfaces of the semiconductor laser chip structure, this embodiment further provides two improved methods. Figure 5 , Figure 6 ,or Figure 7 , Figure 8In some embodiments of the present application, a portion of the first ohmic contact layer 21, the resistance control layer 22, and the second ohmic contact layer 23 in the current injection region Ia form a plurality of heavily doped islands spaced apart, and the heavily doped islands constitute a second current injection window Iw b ; The first current injection window Iw a Surrounding the second current injection window Iw b .

[0045] For further reference, Figure 5 , Figure 6 ,or Figure 7 , Figure 8 ,in Figure 5 , Figure 7 The insulating isolation layer 3 and the P-side electrode 4 covering the top of the device are hidden. In some embodiments of the present application, along the direction from the back cavity surface to the front cavity surface of the semiconductor laser, a plurality of second current injection windows Iw b The distribution of the interval, and in the direction from the rear cavity surface to the front cavity surface, the adjacent second current injection window Iw b The interval gradually increases.

[0046] It should be noted that the first ohmic contact layer 21 and the second ohmic contact layer 23 are shown as different graphics in the figure in order to highlight the different film positions. In practical applications, the two can be selected to have the same material and doping concentration. The actual position of the insulating isolation layer 3 and the P-side electrode 4 can be referred to Figure 6 , Figure 8 .

[0047] The semiconductor laser chip structure provided by the present application has a plurality of second current injection windows Iw arranged at intervals. b , the first current injection window Iw can be a Occupies a larger area to ensure as much current injection as possible, while the second current injection window Iw b The spacing distribution gradually increases from the rear cavity surface to the front cavity surface, so that the closer to the rear cavity surface, the higher the carrier suppression degree, and the closer to the front cavity surface, the lower the suppression degree, thereby balancing the carrier injection conditions of the front and rear cavity surfaces.

[0048] Specifically, in different implementations: The second current injection window Iw b The width is 10μm~100μm.

[0049] The second current injection window Iw b The distance from the side boundary of the current injection region Ia is 5 μm to 10 μm.

[0050] The second current injection window Iw closest to the rear cavity surface bThe distance between the boundary of the current injection region Ia close to the rear cavity surface is 5 μm to 10 μm.

[0051] The second current injection window Iw closest to the rear cavity surface b The edge close to the rear cavity surface and the second current injection window Iw closest to the front cavity surface b The ratio of the distance between the edges close to the front cavity surface and the total size of the current injection area Ia in the direction from the front cavity surface to the rear cavity surface is 1:1 to 1:5.

[0052] In the direction from the rear cavity surface to the front cavity surface, the adjacent second current injection window Iw b The spacing between them is S1, S2, ... S n , S n-1 :S n The ratio is 1:1~1:10, and S1 is 10μm~200μm.

[0053] For further reference, Figure 5 , Figure 6 ,or Figure 7 , Figure 8 In some implementations of the present application, the semiconductor laser provided in this embodiment further includes: The first isolation trench 101 is located on the heavily doped stage 2 and on both sides of the current injection region Ia; the bottom of the first isolation trench 101 penetrates deep into the upper confinement layer 17; An insulating isolation layer 3, the insulating isolation layer 3 covers the surface of the heavily doped stage 2 outside the current injection region Ia facing away from the substrate layer 11 and the exposed surface of the laser substrate 1 facing away from the substrate layer 11; A P-surface electrode 4, the P-surface electrode 4 covers the surface of the current injection region Ia facing away from the substrate layer 11 and the surface of the insulating isolation layer 3 facing away from the substrate layer 11; N-side electrode 5, the N-side electrode 5 covers the surface of the substrate layer 11 facing away from the upper limiting layer 17; exist Figure 5 , Figure 6 In the embodiment, the top projection area of ​​the heavily doped platform 2 on the laser substrate 1 is smaller than the area of ​​the laser substrate 1 ; the laser substrate 1 has exposed platforms around the heavily doped platform 2 .

[0054] Or, in Figure 7 , Figure 8 In the embodiment, the top projection area of ​​the heavily doped stage 2 on the laser substrate 1 is equal to the area of ​​the laser substrate 1; the heavily doped stage 2 is provided with non-current injection limiting grooves 102 on the front cavity surface side and the back cavity surface side respectively; the non-current injection limiting grooves 102 are spaced apart from the current injection area Ia.

[0055] The semiconductor laser chip structure provided by the present application is provided with first isolation grooves 101 on both sides of the lateral direction of the current injection region, and the current injection region can be defined. That is, the current injection region is in the Y direction, and the starting point and the end point are the distance between the two first isolation grooves 101. In addition, since the areas near the front cavity surface and the rear cavity surface are high-incidence areas of COMD and COBD, a non-current injection limiting groove 102 is provided here to further suppress the injection of current, reduce the failure risk of the semiconductor laser chip, and improve reliability.

[0056] Example 2 This embodiment provides a method for manufacturing a semiconductor laser chip structure, which is used to manufacture the semiconductor laser chip structure of the above-mentioned embodiment 1. The method comprises the following steps: A laser substrate 1 is formed, wherein the laser substrate 1 comprises: a substrate layer 11, a buffer layer 12, a lower confinement layer 13, a lower waveguide layer 14, a quantum well active layer 15, an upper waveguide layer 16 and an upper confinement layer 17 which are stacked in sequence; A heavily doped platform 2 is formed. The heavily doped platform 2 is formed on the surface of the upper confinement layer 17 of the laser substrate 1 which faces away from the substrate layer 11 and includes a first ohmic contact layer 21, a second ohmic contact layer 23 and a resistance control layer 22; The resistance control layer 22 is disposed between the first ohmic contact layer 21 and the second ohmic contact layer 23, and the resistance value thereof is greater than the resistance value of the first ohmic contact layer 21 and the resistance value of the second ohmic contact layer 23; A current injection region Ia is formed in the heavily doped stage 2; a first current injection window Iw is formed in the current injection region Ia a and the second current injection window Iw b ; Among them, the first current injection window Iw a The current path to the substrate layer 11 does not pass through the resistance control layer 22, and the second current injection window Iw b The current path to the substrate layer 11 passes through the resistance control layer 22 .

[0057] The semiconductor laser chip structure has a front cavity surface and a back cavity surface opposite to each other in the length direction of the laser substrate; the second current injection window Iw b At least it is formed on the side of the current injection region Ia close to the back cavity surface.

[0058] The manufacturing method of the semiconductor laser chip structure provided in this embodiment can manufacture the semiconductor laser chip structure provided in the above-mentioned embodiment 1. The laser chip structure manufactured by the manufacturing method of the semiconductor laser chip structure provided in this application has an ohmic contact layer on the upper limiting layer 17, which changes the conventional single-layer structure into a double-layer ohmic contact layer sandwiching a resistance control layer 22. The resistance value of the resistance control layer 22 is respectively greater than the ohmic contact layers on the upper and lower sides, and cooperates with the first current injection window Iw a and the second current injection window Iw b The setting makes the second current injection window Iw b Since the current path needs to pass through the resistance control layer 22, the resistance control layer 22 has a relatively high resistance value, which can suppress the second current injection window Iw. b Therefore, the second current is injected into the window Iw b At least one side of the back cavity surface is set to suppress the carrier injection near the back cavity surface. a It can meet the conventional current injection requirements, and the carriers are not suppressed from conventional injection. a and the second current injection window Iw b Different settings can be used to balance the carrier injection conditions in different areas, so as to achieve carrier injection balance between the front and rear cavity surfaces of the semiconductor laser, thereby ensuring that the temperature rise of the front and rear cavity surfaces is basically the same, thereby avoiding the problem of local failure of the front cavity surface, improving the reliability of the semiconductor laser; and improving the electro-optical conversion efficiency of the semiconductor laser. In addition, when the P surface of the semiconductor laser (i.e., the side of the P surface electrode 4) is flipped down on the heat sink for use, due to the second current injection window Iw b The quantum well active layer 15 in the region is closer to the solder and the heat sink, the heat dissipation path is shorter, and the higher temperature generated on the front cavity surface is more easily conducted away through the heat sink, making the heat distribution at the front and rear cavity surfaces more balanced, which can effectively suppress the thermal lens effect, thereby reducing the far-field horizontal divergence angle to a certain extent and improving the device performance and reliability.

[0059] Further, in some embodiments of the present application, when forming the first current injection window Iw a and the second current injection window Iw b In the step of etching, the heavily doped stage 2 is processed, wherein the first current injection window Iw a The etching end point is located in the first ohmic contact layer 21 close to the upper limiting layer 17, and the second current injection window Iw b The etching endpoint is located in the second ohmic contact layer 23 away from the upper limit.

[0060] Furthermore, in some embodiments of the present application, a first current injection window Iw is formed in the current injection region Ia. a and the second current injection window Iw b In the step of etching, a portion of the first ohmic contact layer 21, the resistance control layer 22 and the second ohmic contact layer 23 in the current injection region Ia is etched to form a plurality of heavily doped islands spaced apart, and the heavily doped islands constitute the second current injection window Iw b ; The first current injection window Iw a Surrounding the second current injection window Iw b .

[0061] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection created by this application.

Claims

1. A semiconductor laser chip structure, characterized in that: The semiconductor laser chip structure comprises: A laser matrix, the laser matrix comprising: a substrate layer, a buffer layer, a lower confinement layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer and an upper confinement layer stacked in sequence; A heavily doped stage, arranged on the surface of the upper limiting layer of the laser substrate facing away from the substrate layer, comprising a first ohmic contact layer, a second ohmic contact layer and a resistance control layer; the resistance control layer is arranged between the first ohmic contact layer and the second ohmic contact layer; the resistance value of the resistance control layer is respectively greater than the resistance value of the first ohmic contact layer and the resistance value of the second ohmic contact layer; The heavily doped platform is divided into a current injection area, and the current injection area is provided with a first current injection window and a second current injection window; Wherein, the current path from the first current injection window to the substrate layer does not pass through the resistance control layer, and the current path from the second current injection window to the substrate layer passes through the resistance control layer; The semiconductor laser chip structure has a front cavity surface and a rear cavity surface opposite to each other in the length direction of the laser substrate; The second current injection window is at least arranged on a side of the current injection region close to the rear cavity surface.

2. The semiconductor laser chip structure according to claim 1, characterized in that: The bottom of the first current injection window is located in the first ohmic contact layer close to the upper confinement layer, and the bottom of the second current injection window is located in the second ohmic contact layer far from the upper confinement layer.

3. The semiconductor laser chip structure according to claim 1, characterized in that: The doping concentration of the resistance control layer is less than the doping concentration of the first ohmic contact layer and the doping concentration of the second ohmic contact layer; and / or, The thickness of the resistance control layer is less than or equal to the thickness of the first ohmic contact layer and the thickness of the second ohmic contact layer.

4. The semiconductor laser chip structure according to claim 3, characterized in that: The doping concentration of the first ohmic contact layer is 2E19 cm -3 ~1E20 cm -3 ; The doping concentration of the second ohmic contact layer is 2E19 cm -3 ~1E20 cm -3 ; The resistance control doping concentration is 1E17 cm -3 ~1E20 cm -3 ; The thickness of the first ohmic contact layer is 200nm-800nm; The thickness of the second ohmic contact layer is 200nm-800nm; The thickness of the resistance control layer is 200nm~500nm; The distance between the bottom of the first current injection window and the bottom of the first ohmic contact layer is 200nm-500nm; The distance between the bottom of the second current injection window and the bottom of the second ohmic contact layer is 200 nm to 500 nm.

5. The semiconductor laser chip structure according to claim 1, characterized in that: Part of the first ohmic contact layer, the resistance control layer and the second ohmic contact layer in the current injection region form a plurality of spaced heavily doped islands, and the heavily doped islands constitute a second current injection window; The first current injection window surrounds the second current injection window.

6. The semiconductor laser chip structure according to claim 5, characterized in that: A plurality of second current injection windows are spaced apart along the direction from the back cavity surface to the front cavity surface of the semiconductor laser chip structure, and the intervals between adjacent second current injection windows gradually increase in the direction from the back cavity surface to the front cavity surface.

7. The semiconductor laser chip structure according to claim 6, characterized in that: The width of the second current injection window is 10 μm to 100 μm; The distance between the second current injection window and the side boundary of the current injection area is 5 μm to 10 μm; The distance between the second current injection window closest to the rear cavity surface and the boundary of the current injection area close to the rear cavity surface is 5 μm-10 μm; The ratio of the distance between the edge of the second current injection window closest to the rear cavity surface close to the rear cavity surface and the edge of the second current injection window closest to the front cavity surface close to the front cavity surface to the total size of the current injection area in the direction from the front cavity surface to the rear cavity surface is 1:1-1:5; In the direction from the rear cavity surface to the front cavity surface, the spacings between adjacent second current injection windows are S1, S2, ..., S n , S n-1 :S n The ratio is 1:1~1:10, and S1 is 10μm~200μm.

8. The semiconductor laser chip structure according to claim 1, characterized in that: Also includes: A first isolation trench is located on the heavily doped platform and on both sides of the current injection region; the bottom of the first isolation trench penetrates deep into the upper confinement layer; An insulating isolation layer, wherein the insulating isolation layer covers the surface of the heavily doped platform outside the current injection region facing away from the substrate layer and the exposed surface of the laser substrate facing away from the substrate layer; A P-side electrode, the P-side electrode covers a surface of the current injection region facing away from the substrate layer and a surface of the insulating isolation layer facing away from the substrate layer; An N-side electrode, the N-side electrode covers a surface of the substrate layer facing away from the upper restriction layer; The top-view projection area of ​​the heavily doped platform on the laser substrate is smaller than the area of ​​the laser substrate; the laser substrate has exposed platforms around the heavily doped platform; Alternatively, the top-view projection area of ​​the heavily doped platform on the laser substrate is equal to the area of ​​the laser substrate; the heavily doped platform is provided with non-current injection limiting grooves on one side of the front cavity surface and one side of the back cavity surface respectively; the non-current injection limiting grooves are spaced apart from the current injection area.

9. A method for manufacturing a semiconductor laser chip structure, used for manufacturing the semiconductor laser chip structure according to any one of claims 1 to 8, characterized in that: The following steps are involved: Forming a laser matrix, the laser matrix comprising: a substrate layer, a buffer layer, a lower confinement layer, a lower waveguide layer, a quantum well active layer, an upper waveguide layer and an upper confinement layer stacked in sequence; A heavily doped platform is formed, wherein the heavily doped platform is formed on a surface of an upper limiting layer of the laser substrate facing away from the substrate layer, and comprises a first ohmic contact layer, a second ohmic contact layer and a resistance control layer; the resistance control layer is arranged between the first ohmic contact layer and the second ohmic contact layer, and the resistance value of the resistance control layer is respectively greater than the resistance value of the first ohmic contact layer and the resistance value of the second ohmic contact layer; forming a current injection region on the heavily doped platform; forming a first current injection window and a second current injection window in the current injection region; Wherein, the current path from the first current injection window to the substrate layer does not pass through the resistance control layer, and the current path from the second current injection window to the substrate layer passes through the resistance control layer; The semiconductor laser chip structure has a front cavity surface and a rear cavity surface opposite to each other in the length direction of the laser substrate; The second current injection window is formed at least on one side of the current injection region close to the rear cavity surface.

10. The method for manufacturing a semiconductor laser chip structure according to claim 9, characterized in that: In the step of forming the first current injection window and the second current injection window, The heavily doped stage is processed by etching, wherein the etching endpoint of the first current injection window is located in the first ohmic contact layer close to the upper confinement layer, and the etching endpoint of the second current injection window is located in the second ohmic contact layer away from the upper confinement layer.

11. The method for manufacturing a semiconductor laser chip structure according to claim 9, characterized in that: In the step of forming a first current injection window and a second current injection window in the current injection region, Part of the first ohmic contact layer, the resistance control layer and the second ohmic contact layer in the current injection region are etched to form a plurality of heavily doped islands at intervals, wherein the heavily doped islands constitute second current injection windows; The first current injection window surrounds the second current injection window.

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