Semiconductor laser epitaxial structure and preparation method
By setting a segmented resonant cavity on the ridge waveguide of the semiconductor laser chip and controlling the reflectance of the resonant cavity, the uniform distribution of photons and carriers is achieved, the problem of longitudinal space burning effect is solved, and the output power and power are significantly improved density.
Patent Information
- Application Number
- CN202411324744.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-23
- Publication Date
- 2025-01-10
AI Technical Summary
When existing semiconductor laser chips increase output power and power density, longitudinal space burning effect is prone to occur, resulting in a decrease in maximum output power and deterioration of beam quality.
Using the epitaxial structure of semiconductor lasers, by setting a segmented resonant cavity on the ridge waveguide and controlling the reflectivity of the front cavity surface of different resonant cavity, the uniform distribution of photons and carriers in the longitudinal direction is ensured, and the longitudinal spatial burning effect is eliminated. Specific measures include growing multi-layer structures sequentially on the substrate, forming waveguide grooves on the ohmic contact layer, forming ridge waveguides, and installing DBR structures on them, gradually increasing the length of the ridge waveguide segments and reducing the number of gratings in DBR. .
The output power and power density of the chip are significantly improved under the same luminous area, completely eliminating the power saturation and beam quality deterioration caused by the longitudinal space burning effect.
Smart Images
Figure CN119297738A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of semiconductor lasers, in particular to a semiconductor laser epitaxial structure and a preparation method thereof. Background Art
[0002] Semiconductor lasers have been widely used and developed in the fields of pumping, industrial processing, medical cosmetology, military scientific research, and communications due to their small size, direct photoelectric conversion, high efficiency, and simple preparation process.
[0003] The key parameters of semiconductor laser chips include output power, photoelectric conversion efficiency, beam quality, etc. Among them, output power is the core photoelectric parameter, and its value represents the level of chip development to a certain extent. From the pulse μW level on the day of its birth to the current continuous output W level, the output power and power density of semiconductor laser chips have been greatly improved, but with the further development of technology, it is now more difficult to improve the output power and power density of semiconductor laser chips.
[0004] At present, there are two main mainstream technical solutions for high-power semiconductor laser chips. One is to increase the output power of the chip by increasing the area of the light-emitting area; the other is to increase the area of the gain area and improve the heat dissipation efficiency by increasing the cavity length, thereby increasing the output power. In order to improve the external quantum efficiency, the reflectivity of the front cavity surface of the semiconductor laser chip is getting lower and lower, and the reflectivity of the back cavity surface is close to 100%. However, the above two solutions will make the photon density and carrier density distribution along the cavity length direction (that is, "longitudinal") seriously uneven, that is, forming the so-called "longitudinal space hole burning effect", which will cause the maximum output power of the chip to become lower and the beam quality to deteriorate, seriously affecting the maximum output power density of the chip. Summary of the invention
[0005] In response to the above problems, the present application provides a semiconductor laser epitaxial structure and a preparation method which can significantly improve the output power of the chip under the premise of the same light-emitting area.
[0006] The technical solution adopted by the present invention to solve the technical problem is:
[0007] A semiconductor laser epitaxial structure, comprising, from bottom to top, a substrate, an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer and an ohmic contact layer;
[0008] Two waveguide grooves are arranged on the ohmic contact layer, and a ridge waveguide is formed between the two waveguide grooves;
[0009] The ridge waveguide includes a plurality of ridge waveguide segments along the light output direction, and a DBR structure is arranged between adjacent ridge waveguide segments to improve the uniformity of the distribution of carriers and photons in the longitudinal direction.
[0010] Furthermore, the waveguide groove extends downward into the P-type confinement layer.
[0011] Furthermore, a corrosion barrier layer is provided in the P-type confinement layer, and the waveguide groove extends downward to the corrosion barrier layer.
[0012] Furthermore, the DBR structure extends downward to the P-type waveguide layer.
[0013] Furthermore, an etching stop layer is provided between the P-type waveguide layer and the P-type confinement layer, and the DBR structure extends downward to the etching stop layer.
[0014] Furthermore, along the light emitting direction, the length of the ridge waveguide section gradually increases, and the number of gratings in the DBR structure gradually decreases.
[0015] A method for preparing a semiconductor laser epitaxial structure comprises the following steps:
[0016] First, epitaxially growing an N-type confinement layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, a P-type confinement layer and an ohmic contact layer on a substrate in sequence to form a basic epitaxial structure;
[0017] Second, two waveguide grooves are processed on the basic epitaxial structure obtained in the first step to form a ridge waveguide;
[0018] Third, a plurality of DBR structures are processed on the ridge waveguide obtained in the second step, so as to divide the ridge waveguide into a plurality of ridge waveguide segments along the light output direction.
[0019] Furthermore, an etch barrier layer is grown between the P-type waveguide layer and the P-type confinement layer, and a corrosion barrier layer is grown within the P-type confinement layer.
[0020] Furthermore, the waveguide groove is processed by a wet etching process, and the DBR structure is processed by a dry etching process, and extends downward to the etching stop layer.
[0021] Furthermore, along the light emitting direction, the length of the ridge waveguide section gradually increases, and the number of gratings in the DBR structure gradually decreases.
[0022] The beneficial effects of the present invention are:
[0023] The semiconductor laser epitaxial structure and preparation method provided in the embodiment of the present application, by setting a segmented resonant cavity on the ridge strip and controlling the reflectivity of the front cavity surface of different resonant cavities, the photons and carriers in each resonant cavity and the entire ridge strip are evenly distributed, and the power saturation and beam quality deterioration caused by the longitudinal space hole burning effect are completely eliminated. Under the premise of the same light-emitting area, the output power of the chip is significantly improved, that is, the power density of the chip is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 A processing process of a semiconductor laser epitaxial structure provided in an embodiment of the present application Figure 1 ;
[0025] Figure 2 A processing process of a semiconductor laser epitaxial structure provided in an embodiment of the present application Figure 2 ;
[0026] Figure 3 A processing process of a semiconductor laser epitaxial structure provided in an embodiment of the present application Figure 3 ;
[0027] Figure 4 This is a diagram of the epitaxial stacking structure of the semiconductor laser after the DBR is completed and the epitaxial structure is cut longitudinally on the ridge waveguide.
[0028] In the figure: 101, substrate; 102, N-type confinement layer; 103, N-type waveguide layer; 104, active layer; 105, P-type waveguide layer; 106, P-type confinement layer; 107, ohmic contact layer; 108, etch barrier layer; 109, corrosion barrier layer;
[0029] 200, waveguide groove;
[0030] 300, ridge waveguide; 301, first ridge waveguide segment; 302, second ridge waveguide segment; 303, third ridge waveguide segment; 304, fourth ridge waveguide segment;
[0031] 401, first DBR structure; 402, second DBR structure; 403, third DBR structure. DETAILED DESCRIPTION
[0032] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described in detail below in conjunction with the drawings in the embodiments of the present application, and the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by those skilled in the art without creative work on the basis of the embodiments of the present application shall belong to the protection scope of the present application.
[0033] like Figure 1 , Figure 2 and Figure 3 As shown, a semiconductor laser epitaxial structure includes a substrate 101, an N-type confinement layer 102, an N-type waveguide layer 103, an active layer 104, a P-type waveguide layer 105, a P-type confinement layer 106 and an ohmic contact layer 107 from bottom to top. The ohmic contact layer 107 is provided with two waveguide grooves 200 extending along the light emitting direction, and the waveguide grooves 200 penetrate downwardly through the ohmic contact layer 107 and extend into the P-type confinement layer 106, and a ridge waveguide 300 is formed between the two waveguide grooves 200. The ridge waveguide 300 is a segmented structure, including a plurality of ridge waveguide segments along the light emitting direction, and a DBR structure (Bragg grating) is provided between adjacent ridge waveguide segments. The DBR structure extends downwardly to the P-type waveguide layer 105.
[0034] Here, the number of segments of the ridge waveguide 300 is determined according to the cavity length. As a specific implementation, the ridge waveguide 300 described in this embodiment is divided into four sections, which are the first ridge waveguide section 301, the second ridge waveguide section 302, the third ridge waveguide section 303 and the fourth ridge waveguide section 304 in the light emitting direction. A first DBR structure 401 is arranged between the first ridge waveguide section 301 and the second ridge waveguide section 302, a second DBR structure 402 is arranged between the second ridge waveguide section 302 and the third ridge waveguide section 303, and a third DBR structure 403 is arranged between the third ridge waveguide section 303 and the fourth ridge waveguide section 304.
[0035] The ridge waveguide 300 adopts a segmented structure, and different ridge waveguide segments are isolated by a DBR structure, so that the large cavity length ridge waveguide is divided into multiple small cavity length ridge waveguides. The small cavity length ridge waveguide can effectively improve the uniformity of the longitudinal distribution of carriers and photons, thereby weakening the longitudinal spatial hole burning effect to a certain extent.
[0036] Furthermore, along the light emitting direction, the length of the ridge waveguide section gradually increases, and the number of gratings in the DBR structure gradually decreases.
[0037] The lengths of the ridge waveguide segments of the segmented ridge waveguide 300 increase successively along the cavity length direction, and the number of gratings in the DBR structure decreases successively along the cavity length direction, which can effectively increase the photon density at the rear cavity surface and reduce the carrier density, thereby achieving the purpose of completely eliminating longitudinal spatial hole burning.
[0038] Furthermore, an etch stop layer 108 is disposed between the P-type waveguide layer 105 and the P-type confinement layer 106 , and the DBR structure extends downward to the etch stop layer 108 .
[0039] By providing the etching stop layer 108 , it can be ensured that the etching depth of the DBR structure does not exceed the P-type waveguide layer 105 , thereby avoiding damage to the P-type waveguide layer 105 , and at the same time, the consistency of the etching depth of the DBR structure can be ensured.
[0040] Furthermore, a corrosion barrier layer 109 is provided in the P-type confinement layer 106, and the corrosion barrier layer 109 divides the P-type confinement layer 106 into two layers, an upper layer and an lower layer. For the convenience of understanding and description, the P-type confinement layer 106 located on the upper and lower sides of the corrosion barrier layer 109 are named as an upper P-type confinement layer and a lower P-type confinement layer, respectively. The waveguide slot 200 sequentially passes downward through the ohmic contact layer 107 and the upper P-type confinement layer and extends to the corrosion barrier layer 109.
[0041] The provision of the corrosion barrier layer 109 can ensure the consistency of the depth of the waveguide groove 200 , thereby ensuring the consistency of the preparation of the ridge waveguide 300 .
[0042] By providing the etching stop layer 108 and the corrosion stop layer 109, the depth of subsequent waveguide groove 200 etching and DBR structure etching can be precisely controlled, thereby ensuring the performance consistency of the manufactured chip.
[0043] A method for preparing a semiconductor laser epitaxial structure comprises the following steps:
[0044] First, an N-type confinement layer 102, an N-type waveguide layer 103, an active layer 104, a P-type waveguide layer 105, a P-type confinement layer 106 and an ohmic contact layer 107 are epitaxially grown on a substrate 101 in sequence to form a Figure 1 The basic epitaxial structure shown.
[0045] Second, if Figure 2 As shown, two waveguide grooves 200 are processed on the basic epitaxial structure obtained in the first step to form a ridge waveguide 300.
[0046] Third, if Figure 3 As shown, several DBR structures are processed on the ridge waveguide 300 obtained in the second step, so that the ridge waveguide 300 is divided into several ridge waveguide segments along the light emitting direction, and along the light emitting direction, the length of the ridge waveguide segment gradually increases, and the number of gratings in the DBR structure gradually decreases.
[0047] Furthermore, an etch barrier layer 108 is grown between the P-type waveguide layer 105 and the P-type confinement layer 106, and a corrosion barrier layer 109 is grown in the P-type confinement layer 106. That is, after the growth of the P-type waveguide layer 105 is completed, the etch barrier layer 108 is grown, and then a lower P-type confinement layer is grown on the upper surface of the etch barrier layer 108, and then a corrosion barrier layer 109 is grown on the upper surface of the lower P-type confinement layer, and then an upper P-type confinement layer is grown on the upper surface of the corrosion barrier layer 109.
[0048] The waveguide groove 200 is formed by wet etching, because the wet etching process will stop during the etching process due to the presence of the corrosion barrier layer 109 , that is, the etching depth is determined by the corrosion barrier layer 109 , thus ensuring the consistency of the depth of the waveguide groove 200 .
[0049] The DBR structure is processed by dry etching process, and Figure 4 It is shown extending down to the etch stop layer 108 .
[0050] Other embodiments obtained by those skilled in the art by combining, splitting, reorganizing, etc. the embodiments of the present application on the basis of the embodiments provided in the present application do not exceed the protection scope of the present application.
[0051] The above specific implementation methods have detailed the purpose, technical solutions and beneficial effects of the embodiments of the present application. The above are only specific implementation methods of the embodiments of the present application and are not used to limit the protection scope of the embodiments of the present application. That is, any modifications, equivalent substitutions, improvements, etc. made on the basis of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.
Claims
1. A semiconductor laser epitaxial structure, characterized in that: The invention comprises, from bottom to top, a substrate (101), an N-type confinement layer (102), an N-type waveguide layer (103), an active layer (104), a P-type waveguide layer (105), a P-type confinement layer (106) and an ohmic contact layer (107); Two waveguide grooves (200) are arranged on the ohmic contact layer (107), and a ridge waveguide (300) is formed between the two waveguide grooves (200); The ridge waveguide (300) comprises a plurality of ridge waveguide segments along the light output direction, and a DBR structure is arranged between adjacent ridge waveguide segments.
2. A semiconductor laser epitaxial structure according to claim 1, characterized in that: The waveguide groove (200) extends downward into the P-type confinement layer (106).
3. A semiconductor laser epitaxial structure according to claim 2, characterized in that: A corrosion barrier layer (109) is provided in the P-type confinement layer (106), and the waveguide groove (200) extends downward to the corrosion barrier layer (109).
4. A semiconductor laser epitaxial structure according to claim 1, characterized in that: The DBR structure extends downward to the P-type waveguide layer (105).
5. A semiconductor laser epitaxial structure according to claim 4, characterized in that: An etching stop layer (108) is provided between the P-type waveguide layer (105) and the P-type confinement layer (106), and the DBR structure extends downward to the etching stop layer (108).
6. The semiconductor laser epitaxial structure according to claim 1, characterized in that: Along the light emitting direction, the length of the ridge waveguide section gradually increases, and the number of gratings in the DBR structure gradually decreases.
7. A method for preparing a semiconductor laser epitaxial structure, characterized in that: The following steps are included: First, epitaxially growing an N-type confinement layer (102), an N-type waveguide layer (103), an active layer (104), a P-type waveguide layer (105), a P-type confinement layer (106) and an ohmic contact layer (107) on a substrate (101) in sequence to form a basic epitaxial structure; Second, processing two waveguide grooves (200) on the basic epitaxial structure obtained in the first step to form a ridge waveguide (300); Third, a plurality of DBR structures are processed on the ridge waveguide (300) obtained in the second step, so as to divide the ridge waveguide (300) into a plurality of ridge waveguide segments along the light output direction.
8. The method for preparing a semiconductor laser epitaxial structure according to claim 7, characterized in that: An etching stop layer (108) is grown between the P-type waveguide layer (105) and the P-type confinement layer (106), and a corrosion stop layer (109) is grown inside the P-type confinement layer (106).
9. The method for preparing a semiconductor laser epitaxial structure according to claim 8, characterized in that: The waveguide groove (200) is formed by a wet etching process, and the DBR structure is formed by a dry etching process, and extends downward to the etching stop layer (108).
10. The method for preparing a semiconductor laser epitaxial structure according to claim 7, characterized in that: Along the light emitting direction, the length of the ridge waveguide section gradually increases, and the number of gratings in the DBR structure gradually decreases.