Laser chip, laser module, optical module, and laser device

Abstract

A laser chip and a preparation method therefor, a laser module, an optical module, and a laser device. The laser chip comprises at least two laser epitaxial structures, and the laser epitaxial structures are sequentially vertically stacked and cascaded on a substrate in a second direction. One of an n-side electrode and a p-side electrode is located on the side of the substrate distant from the laser epitaxial structures in the second direction, and the other is located on the side of the laser epitaxial structures distant from the substrate in the second direction. By means of such an arrangement, laser epitaxial structures can be respectively provided corresponding to three primary colors of RGB to achieve lasing at different wavelengths. By cascading and integrating laser epitaxial structures of the three primary colors of RGB on a single chip, monolithic white light output is achieved, no beam combining arrangement is required at a back end, and cost and size can be further reduced. Furthermore, lasing at different wavelengths can be achieved for a same primary color, so that speckle in a projection scene can be effectively reduced, and when each laser epitaxial structure corresponds to a single wavelength, light output power can be increased.

Description

A laser chip, laser module, optical module, and laser device.

[0001] This application claims priority to Chinese Patent Application No. 202510381427.9, filed with the State Intellectual Property Office of China on March 27, 2025, entitled "A Laser Chip, Laser Module, Optical Module and Laser Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of semiconductor technology, and in particular to a laser chip, laser module, optical module and laser device. Background Technology

[0003] Among third-generation semiconductor materials, group III nitrides possess characteristics such as large bandgap, high breakdown voltage, high thermal conductivity, high electron saturation drift velocity, and strong chemical stability, and have found applications in the laser field, meeting the requirements of laser display / projection light source modules. A typical gallium nitride (GaN) chip structure includes, from bottom to top, an n-type electrode, an n-type GaN substrate, a laser epitaxial structure, and a p-type electrode, forming a single-wavelength laser chip. To achieve high power, it is usually necessary to increase the operating current, which leads to problems such as reduced luminous efficiency, increased heat dissipation, decreased efficiency, and increased substrate size. For applications integrating red (R), green (G), and blue (B) primary colors, three or more laser chips of different wavelengths need to be configured in the same light source module; at the same time, due to the physical separation of the RGB primary color beams, multiple mirrors and prisms are needed at the back end of the module for beam combining to reduce the beam spacing, making it impossible to reasonably control the chip configuration cost and the size and cost of the module.

[0004] Furthermore, due to the single-wavelength characteristics of this chip architecture, coupled with the high coherence of lasers, speckle issues arise when applied in projection scenarios, affecting the visual effect. Summary of the Invention

[0005] This application provides a laser chip, a laser module, an optical module, and a laser device. Through structural optimization of the chip architecture, it can effectively improve speckle that may be generated by a single wavelength while increasing power, and provides a good technical guarantee for reasonable control of product size and implementation cost.

[0006] The first aspect of this application provides a laser chip, which includes an n-side electrode, a substrate, laser epitaxial structures, and a p-side electrode. At least two laser epitaxial structures are provided, stacked and cascaded sequentially along a second direction on the substrate, with a tunnel junction between adjacent laser epitaxial structures. One of the n-side and p-side electrodes is located on the side of the substrate away from the laser epitaxial structure along the second direction, and the other is located on the side of the laser epitaxial structure away from the substrate along the second stacking direction. The second direction is the direction intersecting the plane of the substrate. With this configuration, based on this laser chip architecture, the laser epitaxial structures are stacked and cascaded sequentially, and adjacent lasers can be electrically connected through a tunnel junction. The lasing wavelength of each laser epitaxial structure can be a single wavelength corresponding to the same primary color, that is, the lasing wavelength of each laser epitaxial structure is the same, thus multiplying the output power of a single-wavelength chip. Meanwhile, compared to increasing power by increasing operating current, the laser chip architecture provided in this application can effectively avoid the impact on optical efficiency, heat dissipation, efficiency, and substrate size.

[0007] Furthermore, based on this laser chip architecture, laser epitaxial structures can be set for each of the RGB primary colors to achieve lasing at different wavelengths. Adjacent lasers can be electrically connected via tunnel junctions. Therefore, monolithic white light output can be achieved by cascading and integrating RGB primary color laser epitaxial structures onto a single chip. This allows for reasonable control of chip configuration costs. Moreover, compared to solutions using multiple single-wavelength laser chips, the laser chip architecture provided in this application allows for monolithic white light output, further reducing the implementation cost of the light source module. Additionally, the light source module does not require beam coupling at the rear end, further reducing module cost and size.

[0008] Furthermore, based on this laser chip architecture, at least two laser epitaxial structures can be set for the same primary color, and different wavelengths of lasing can be achieved for the same primary color. This can effectively improve speckle in the projection scene. In other words, by appropriately widening the wavelength range, the perceptibility of speckle can be eliminated, thereby improving the user experience.

[0009] For example, both the substrate and the laser epitaxial structure can be made of group III nitrides.

[0010] Based on the first aspect, this application also provides a first implementation of the first aspect: epitaxial structures of lasers with different lasing wavelengths are arranged in a manner that increases sequentially along a second direction. In practical applications, three epitaxial structures are configured, namely, a third epitaxial structure, a second epitaxial structure, and a first epitaxial structure stacked and cascaded sequentially; the lasing wavelength of the third epitaxial structure is 600nm to 700nm, the lasing wavelength of the second epitaxial structure is 500nm to 570nm, and the lasing wavelength of the first epitaxial structure is 400nm to 470nm. Thus, RGB three-primary-color laser epitaxial structures are cascaded and integrated on a single chip, achieving reliable output of monolithic white light.

[0011] Based on the first aspect, this application also provides a second implementation of the first aspect: the lasing wavelength of each laser epitaxial structure corresponds to the same primary color, and the lasing wavelength spacing of each laser epitaxial structure is no greater than 10 nm. Therefore, achieving lasing with different wavelengths for the same primary color can effectively improve speckle in the projection scene, thereby further enhancing the user experience.

[0012] Based on the first aspect, or the first embodiment of the first aspect, or the second embodiment of the first aspect, this application also provides a third embodiment of the first aspect: the substrate is an n-type substrate, the n-side electrode is an n-type electrode electrically connected to the n-type substrate, and the laser epitaxial structure along the second direction sequentially includes an n-type buffer layer, an n-type confinement layer, an n-side waveguide layer, an active region, a p-side waveguide layer, a p-type confinement layer, and a p-type contact layer; the p-side electrode is electrically connected to the p-type contact layer of the laser epitaxial structure located at the top of the stack.

[0013] Based on the third implementation of the first aspect, this application also provides a fourth implementation of the first aspect: a tunnel junction is formed between the p-side electrode and the laser epitaxial structure located on top of the stack. This further enhances electrical conductivity.

[0014] Based on the first aspect, or the first embodiment of the first aspect, or the second embodiment of the first aspect, or the third embodiment of the first aspect, or the fourth embodiment of the first aspect, this application also provides a fifth embodiment of the first aspect: the waveguide of the laser chip is located on the p-side, and the laser chip further includes a p-side heat dissipation substrate, which is in full-surface contact with the p-side electrode. Thus, based on this p-side heat dissipation substrate, good heat dissipation function can be provided.

[0015] Based on the fifth implementation of the first aspect, this application also provides a sixth implementation of the first aspect: In at least two laser epitaxial structures that are stacked and cascaded sequentially, the other laser epitaxial structures, excluding the top laser epitaxial structure, extend laterally in a first direction to form independent waveguides, and the independent waveguides are correspondingly provided with p-side electrodes. In this way, the three laser epitaxial structures share a single n-side electrode 101, and the independent driving of each laser epitaxial structure is achieved through the p-side electrode. That is, a corresponding driving current can be applied based on the corresponding p-side electrode to achieve excitation wavelengths in different color gamuts, which can meet the requirements of precise control applications.

[0016] Based on the first aspect, or the first embodiment of the first aspect, or the second embodiment of the first aspect, or the third embodiment of the first aspect, or the fourth embodiment of the first aspect, or the fifth embodiment of the first aspect, or the sixth embodiment of the first aspect, this application also provides a seventh embodiment of the first aspect: the waveguide of the laser chip is located on the n-side, and the substrate of the laser chip is removed. The laser chip also includes a p-side heat dissipation substrate and an n-side heat dissipation substrate. The p-side heat dissipation substrate is in full-surface contact with the p-side electrode, and the n-side heat dissipation substrate is in full-surface contact with the n-side electrode. With this configuration, the p-side electrode can make full-surface contact with the top of the laser epitaxial structure, and based on the removal of the insulating layer on the side of the path, the current injection area of ​​the p-side is maximized, which can effectively reduce the p-side contact resistance and improve the heat dissipation path, thereby reducing the device operating voltage and thermal resistance. As a result, the junction temperature can be further reduced and the device performance and reliability can be improved. In addition, based on the design of the waveguide 103-1 being located on the n-side of the vertically stacked cascaded epitaxial structure, problems such as interlayer short circuits and cavity surface contamination can be avoided, and overall, the device yield can be further improved. Furthermore, based on the design of the waveguide being located on the n-side of the vertically stacked cascaded epitaxial structure, problems such as material damage and resistance spikes that may be caused by dry etching of the p-side waveguide can be further avoided.

[0017] Based on the first implementation of the first aspect, this application also provides an eighth implementation of the first aspect: the active region of each laser epitaxial structure includes one or more quantum well structures;

[0018] The quantum well material of the active region in the epitaxial structure of the first laser is Al. x1 In y1 GaN, the quantum barrier material is Al x4 In y4 GaN, where 0≤x1≤1, 0≤y1≤1, 0≤x4≤1, 0≤y4≤1, and satisfying: 0≤(x1+y1)≤1, 0≤(x4+y4)≤1;

[0019] The quantum well material of the active region in the epitaxial structure of the second laser is Al. x2In y2 GaN, the quantum barrier material is Al x5 In y5 GaN, where 0≤x2≤1, 0≤y2≤1, 0≤x5≤1, 0≤y5≤1, and satisfying: 0≤(x2+y2)≤1, 0≤(x5+y5)≤1;

[0020] The quantum well material of the active region in the third laser epitaxial structure is Al. x3 In y3 GaN, the material for the quantum barrier is Al. x6 In y6 GaN, where 0≤x3≤1, 0≤y3≤1, 0≤x6≤1, 0≤y6≤1, and satisfying: 0≤(x3+y3)≤1, 0≤(x6+y6)≤1.

[0021] Based on the eighth implementation of the first aspect, this application also provides a ninth implementation of the first aspect: y1≤y2≤y3≤0.5; x1<0.05; x2<0.05; x3<0.05; y4≤y5≤y6 <y1;x4≤x5≤x6≤0.2。

[0022] Based on the first embodiment of the first aspect, or the eighth embodiment of the first aspect, this application also provides a tenth embodiment of the first aspect: the waveguide layer of the first laser epitaxial structure is made of Al. x7 In y7 GaN, where 0 ≤ x7 ≤ 1, 0 ≤ y7 ≤ 1, and satisfying: 0 ≤ (x7 + y7) ≤ 1; the waveguide layer material of the second laser epitaxial structure is Al. x8 In y8 GaN, where 0 ≤ x₈ ≤ 1, 0 ≤ y₈ ≤ 1, and satisfying: 0 ≤ (x₈ + y₈) ≤ 1; the waveguide layer material of the third laser epitaxial structure is Al. x9 In y9 GaN, where 0≤x9≤1, 0≤y9≤1, and satisfy: 0≤(x9+y9)≤1.

[0023] For example, 0≤y7≤y8≤y9 <y1;x7<0.05;x8<0.05;x9<0.05。

[0024] Based on the first embodiment of the first aspect, or the eighth embodiment of the first aspect, or the ninth embodiment of the first aspect, this application also provides an eleventh embodiment of the first aspect: the material of the confinement layer of the first laser epitaxial structure is Al. x10 In y10GaN, where 0 ≤ x10 ≤ 1, 0 ≤ y10 ≤ 1, and satisfying: 0 ≤ (x10 + y10) ≤ 1; the confinement layer material of the second laser epitaxial structure is Al. x11 In y11 GaN, where 0 ≤ x11 ≤ 1, 0 ≤ y11 ≤ 1, and satisfying: 0 ≤ (x11 + y11) ≤ 1; the confinement layer material of the third laser epitaxial structure is Al. x12 In y12 GaN, where 0≤x12≤1, 0≤y12≤1, and satisfy: 0≤(x12+y12)≤1.

[0025] For example, x10≤x11≤x12≤0.2; y10<0.05; y11<0.05; y12<0.05.

[0026] Based on the first aspect, or the first embodiment of the first aspect, or the second embodiment of the first aspect, or the third embodiment of the first aspect, or the fourth embodiment of the first aspect, or the fifth embodiment of the first aspect, or the sixth embodiment of the first aspect, or the seventh embodiment of the first aspect, or the eighth embodiment of the first aspect, or the ninth embodiment of the first aspect, or the tenth embodiment of the first aspect, or the eleventh embodiment of the first aspect, this application also provides a twelfth embodiment of the first aspect: the tunnel junction includes an n-type doped layer and a p-type doped layer, wherein the material of the n-type doped layer is Al. x13 In y13 Ga(1-x13-y13)N, the p-type doped layer is made of Al. x14 In y14 Ga(1-x14-y14), where 0≤x13≤1, 0≤y13≤1, 0≤x14≤1, 0≤y14≤1, and satisfy: 0≤(x13+y13)≤1, 0≤(x14+y14)≤1.

[0027] Based on the twelfth embodiment of the first aspect, this application also provides a thirteenth embodiment of the first aspect: the dopant of the n-type doped layer is at least one of silane and germanane, and the doping concentration is 5 × 10⁻⁶. 18 / cm 3 ~2×10 21 / cm 3 The p-type dopant is magnesia-dicero, and the doping concentration is 5 × 10⁻⁶. 18 / cm 3 ~2×10 21 / cm 3 In practical applications, the dopant of the n-type doped layer can be silane, and the doping concentration of silane is higher than that of magnesium diacene.

[0028] Based on the twelfth or thirteenth embodiment of the first aspect, this application also provides a fourteenth embodiment of the first aspect: the tunnel junction further includes an intermediate layer located between the n-type doped layer and the p-type doped layer, and the material of the intermediate layer is Al. x15 Ga (1-x15) N、In y15 Ga (1-y15) N, where 0≤x15≤1, 0≤y15≤1.

[0029] For example, the intermediate layer is n-type doped, and the dopant can be silane. This neutralizes the diffused Mg doping and helps to mitigate band spikes at the interface caused by stress / polarization electric field, improving tunneling efficiency and thus reducing overall resistance.

[0030] Based on the fourteenth embodiment of the first aspect, this application also provides a fifteenth embodiment of the first aspect: the intermediate layer is any one or more of undoped, p-type doped, and n-type doped, and the doping concentration is less than 2 × 10⁻⁶. 21 / cm 3 .

[0031] A second aspect of this application provides a laser module comprising a laser chip, a circuit board, a reflector, and a housing. The laser chip is the laser chip described above, the housing is mounted on the circuit board, and the compatible laser chip and reflector are located inside the housing. This laser module, with its aforementioned laser chip, also reduces cost and size, effectively improves speckle in projection scenes, and avoids the problems that may arise from increasing power by increasing operating current, such as reduced luminous efficiency, increased heat dissipation, decreased efficiency, and excessively large substrate.

[0032] A third aspect of this application provides an optical module comprising a driver chip and a laser chip. The laser chip is the laser chip described above, and the output terminal of the driver chip is electrically connected to the laser chip. Based on the aforementioned laser chip, this optical module also has the advantages of reducing cost and size, effectively improving speckle in projection scenes, and avoiding the problems of reduced luminous efficiency, increased heat dissipation, decreased efficiency, and excessively large substrate that may result from increasing power by increasing operating current.

[0033] A fourth aspect of this application provides a laser device, which includes an optical component and an optical module. The optical module is as described above, and the optical component is used to adjust the optical parameters of the laser output by the optical module. Based on the aforementioned laser chip, this optical module also has the advantages of reducing cost and size, effectively improving speckle in projection scenes, and avoiding the problems that may result in reduced luminous efficiency, increased heat dissipation, decreased efficiency, and excessively large substrates caused by increasing power through increased operating current. Attached Figure Description

[0034] Figure 1 is a schematic diagram of the architecture of a laser chip provided in an embodiment of this application;

[0035] Figure 2 is a schematic diagram showing the relative positional relationship of the laser epitaxial structure shown in Figure 1;

[0036] Figure 3 is a schematic diagram of the architecture of another laser chip provided in an embodiment of this application;

[0037] Figure 4 is a schematic diagram of the architecture of another laser chip provided in an embodiment of this application;

[0038] Figure 5 is a schematic diagram of three tunneling junctions provided in the embodiments of this application;

[0039] Figure 6 is a schematic diagram of the architecture of another laser chip provided in an embodiment of this application;

[0040] Figure 7 is a schematic diagram of the architecture of another laser chip provided in an embodiment of this application;

[0041] Figure 8 is a schematic diagram of the architecture of another laser chip provided in an embodiment of this application;

[0042] Figure 9 is a schematic diagram of another laser chip provided in an embodiment of this application;

[0043] Figure 10 is a simplified process flow diagram of a laser epitaxial structure provided in an embodiment of this application;

[0044] Figure 11 is a schematic diagram of a laser module provided in an embodiment of this application;

[0045] Figure 12 is a schematic diagram of an optical module provided in an embodiment of this application. Detailed Implementation

[0046] This application provides a monolithic vertically stacked laser chip architecture implementation scheme, which can effectively improve speckle that may be generated by a single wavelength while increasing power, and provides technical guarantee for reasonably controlling the size and implementation cost of RGB three-primary-color integrated products.

[0047] Group III nitrides possess characteristics such as large band gaps, high breakdown voltages, high thermal conductivity, high electron saturation drift velocities, and strong chemical stability, enabling them to withstand high power. Here, "Group III nitrides" refers to compounds formed from elements in Group III of the periodic table (such as gallium, indium, and aluminum) and nitrogen from Group V. Examples include, but are not limited to, single-component compounds such as aluminum nitride (AlN), indium nitride (InN), or gallium nitride (GaN), or multi-component compounds such as indium gallium nitride (InGaN), aluminum gallium nitride (AlGaN), or indium gallium aluminum nitride (InGaN / AlGaN). Group III nitrides are direct bandgap materials with continuously tunable band gaps between 0.7 eV (InN) and 6.2 eV (AlN), emitting wavelengths covering the near-infrared, visible, and deep ultraviolet ranges. Therefore, it has been effectively applied in the field of lasers, possessing advantages such as good directionality, high brightness, long lifespan, wide color gamut, and high efficiency under high current. It has broad prospects in fields such as, but not limited to, laser display, laser lighting, and industrial processing. It can meet the needs of laser display and projection light source modules.

[0048] With the development of laser technology, high luminous efficiency, three-color integration, small size, and low cost have become the evolutionary trends of laser source modules. In related technologies, a typical GaN chip includes an n-type electrode, an n-type GaN substrate, a laser epitaxial structure, and a p-type electrode arranged sequentially from bottom to top, forming a single-wavelength laser chip. Based on this single-wavelength laser chip, the laser epitaxial structure can be optimized to improve power; however, the potential for power improvement is limited. To achieve high power, it is usually necessary to increase the operating current, which leads to a series of problems such as reduced luminous efficiency, increased heat dissipation, decreased efficiency, and increased substrate size.

[0049] Furthermore, based on this single-wavelength laser chip, for integrated RGB three-primary-color applications, the light source module needs to be configured with three or more laser chips of different wavelengths, and multiple reflectors and prisms need to be set at the rear of the module to couple the physically separated RGB three-primary-color beams. This makes it impossible to reasonably control the chip configuration cost, as well as the size and cost of the module.

[0050] Furthermore, due to the single-wavelength characteristics of this chip architecture, coupled with the high coherence of lasers, significant speckle issues arise in projection applications, affecting visual quality. Therefore, methods such as optical engine jitter and screen jitter are typically used to eliminate speckle, requiring additional design and implementation costs.

[0051] Based on this, this application provides a laser chip, which includes an n-side electrode, a substrate, a laser epitaxial structure, and a p-side electrode. At least two laser epitaxial structures are provided, stacked sequentially on the substrate, with a tunnel junction between adjacent laser epitaxial structures. One of the n-side electrode and the p-side electrode is located on the side of the substrate away from the laser epitaxial structure in the stack, and the other is located on the side of the laser epitaxial structure away from the substrate in the stacking direction. Here, the substrate and the laser epitaxial structure are made of group III nitrides.

[0052] With this configuration, based on the laser chip architecture, the epitaxial structures of each laser are stacked and cascaded sequentially, and adjacent lasers can be electrically connected through tunnel junctions. The lasing wavelength of each laser epitaxial structure can be a single wavelength corresponding to the same primary color, that is, the lasing wavelength of each laser epitaxial structure is the same. In this way, the output power of a single-wavelength chip can be increased many times over. At the same time, compared with the method of increasing the operating current to increase power, the laser chip architecture provided by the embodiments of this application can effectively avoid the impact on luminous efficiency, heat dissipation, efficiency, and substrate size.

[0053] Furthermore, based on this laser chip architecture, laser epitaxial structures can be set for each of the RGB primary colors to achieve lasing at different wavelengths. Adjacent lasers can be electrically connected via tunnel junctions. Therefore, monolithic white light output can be achieved by cascading and integrating RGB primary color laser epitaxial structures onto a single chip. This allows for reasonable control of chip configuration costs. Moreover, compared to solutions using multiple single-wavelength laser chips, the laser chip architecture provided in this application allows for monolithic white light output, further reducing the implementation cost of the light source module. Additionally, the light source module does not require beam coupling at the rear end, further reducing module cost and size.

[0054] Furthermore, based on this laser chip architecture, at least two laser epitaxial structures can be set for the same primary color, and different wavelengths of lasing can be achieved for the same primary color. This can effectively improve speckle in the projection scene. In other words, by appropriately widening the wavelength range, the perceptibility of speckle can be eliminated, thereby improving the user experience.

[0055] To better understand the technical solutions and effects of this application, without loss of generality, specific embodiments will be described in detail below with reference to the accompanying drawings. Please refer to Figure 1, which is a schematic diagram of the architecture of a laser chip provided in an embodiment of this application.

[0056] As shown in Figure 1, the laser chip 100 includes an n-side electrode 101, an n-type substrate 102, a laser epitaxial structure 103, a tunnel junction 104, and a p-side electrode 107. For ease of description, the figure uses the symbol X to indicate a first direction, which is a direction located in the plane of the n-type substrate 102, i.e., a transverse direction; and uses the symbol Y to indicate a second direction, which is the direction intersecting the plane of the n-type substrate 102, i.e., the longitudinal direction of the laser epitaxial structure grown layer by layer based on the substrate epitaxy. For example, the second direction Y shown in the figure is approximately perpendicular to the first direction X.

[0057] In the second direction Y, an n-type substrate 102 is located above an n-side electrode 101, and three laser epitaxial structures 103 are located above the n-type substrate 102 and are stacked sequentially on the n-type substrate 102. A p-side electrode 107 is located above each laser epitaxial structure 103. In other words, the n-side electrode 101, n-type substrate 102, each laser epitaxial structure 103, and p-side electrode 107 are sequentially arranged in the second direction Y. A tunnel junction 104 is provided between two adjacent laser epitaxial structures 103 to allow electrical conduction. Similarly, a tunnel junction 104 is also provided between the top laser epitaxial structure 103 and the p-side electrode 107 to improve current injection efficiency. In this embodiment, both the n-side electrode 101 and the p-side electrode 107 are n-type electrodes.

[0058] In other specific implementations, in the second direction Y, the laser chip 100 may further include two laser epitaxial structures 103 (not shown in the figure) stacked and cascaded sequentially on the n-type substrate 102. In other possible implementations, the laser chip 100 may also include a plurality of other laser epitaxial structures 103 (not shown in the figure) stacked and cascaded sequentially on the n-type substrate 102, which may be determined according to the overall product design requirements, and are not limited in the embodiments of this application.

[0059] In this embodiment, the three laser epitaxial structures 103 are a first laser epitaxial structure 103a, a second laser epitaxial structure 103b, and a third laser epitaxial structure 103c, as shown in Figure 1. The first laser epitaxial structure 103a, the second laser epitaxial structure 103b, and the third laser epitaxial structure 103c are stacked and cascaded from top to bottom. Specifically, a first tunneling junction 104a is provided at the top of the first laser epitaxial structure 103a, a second tunneling junction 104b is provided between the first laser epitaxial structure 103a and the second laser epitaxial structure 103b, and a third tunneling junction 104c is provided between the second laser epitaxial structure 103b and the third laser epitaxial structure 103c.

[0060] In the specific implementation, each laser epitaxial structure 103 is grown sequentially from the same n-type substrate 102. Please refer to Figures 1 and 2 together, where Figure 2 is a schematic diagram of the relative positional relationship of the laser epitaxial structures shown in Figure 1.

[0061] To further optimize beam quality and reduce threshold current, a strip waveguide 103-1 is formed on the top (P-side) of the uppermost first laser epitaxial structure 103a. The dimensions of this waveguide 103-1 can be determined according to the overall product design requirements, for example, but not limited to, a waveguide width W of 1µm to 100µm, a length L of 100µm to 2000µm, and a height H of 0.2µm to 2000nm. The specific dimensions can be determined according to the overall product design requirements, and this application embodiment does not impose such limitations. Simultaneously, each laser epitaxial structure 103 has a groove portion 103-2 on both sides. In the second direction Y, the groove portion 103-2 extends from the side of the waveguide 103-1 to the bottom layer structure of the third laser epitaxial structure 103c, for example, but not limited to, the n-type confinement layer of the third laser epitaxial structure 103c. Furthermore, an insulating dielectric layer 106 is provided on both sides of the waveguide 103-1 and in the groove portion 103-2 to form effective insulation.

[0062] In specific implementations, the insulating dielectric layer 106 material includes, but is limited to, SiO2 and SiN. x (x=0~1), any one of SiON, Al2O3, AlON, SiAlON, TiO2, Ta2O5, ZrO2 and polycrystalline silicon, or a combination of two or more.

[0063] In practice, the waveguide 103-1 and the groove 103-2 can be formed using any process method such as dry etching or wet etching.

[0064] In this embodiment, the n-side electrode 101 can make full-surface contact with the thinned and polished n-type substrate 102 for reliable electrical connection. For example, but not limited to, the thickness of the n-side electrode 101 can be 5 nm to 3000 nm. The p-side electrode 107 is electrically connected to the first tunnel junction 104a through the n-type contact layer 105 to apply a driving current; wherein, the thickness of the p-side electrode 107 is 0 μm to 10 μm, the n-type contact layer 105 is not in full-surface contact with the second surface of the first tunnel junction 104a, the width of the n-type contact layer 105 is 1 nm to 100 μm (consistent with the waveguide width), the length is 100 nm to 2000 μm (consistent with the waveguide length), and the thickness is 5 nm to 1000 nm.

[0065] It is understood that the materials of the p-side electrode 107 and the n-side electrode 101 include, but are limited to, any one or a combination of two or more of Ni, Ti, Pd, Pt, Au, Al, TiN, ITO and IGZO.

[0066] In a specific implementation, the vertically stacked cascaded epitaxial structure of the laser chip 100 can be achieved through single or multiple epitaxial growth. To improve electrical conduction reliability, an ohmic contact can be formed between the n-side electrode 101 and the first surface of the n-type substrate 102 through annealing, and an ohmic contact can also be formed between the n-type contact layer 105 and the second surface of the first laser epitaxial structure 103a through annealing. The specific choice can be made according to actual process conditions, and this application embodiment does not limit the specific choice.

[0067] Based on the laser chip 100 described in Figure 1, it is suitable for single-drive of multiple laser structures. Depending on the application scenario, effective control of junction temperature can also be achieved by reducing drive current, widening waveguide size and / or configuring a heat dissipation substrate with good thermal conductivity.

[0068] Please refer to Figure 3, which is a schematic diagram of another laser chip architecture provided in an embodiment of this application. To clearly illustrate the differences and connections between this embodiment and the foregoing embodiments, the same functional components or structures are shown in the figure with the same labels.

[0069] Compared to the laser epitaxial structure described in Figure 1, the difference in this embodiment is that it also includes a p-side heat dissipation substrate 108, which is packaged using a chip-on-carrier (COC) process. As shown in Figure 3, the p-side heat dissipation substrate 108 is located above the p-side electrode 107. The p-side heat dissipation substrate 108 is in full-surface contact with the p-side electrode 107, and thus provides good heat dissipation.

[0070] In a specific implementation, the material of the p-side heat dissipation substrate 108 can be any one of silicon substrate (Si), aluminum nitride substrate (AlN), silicon carbide substrate (SiC), diamond, etc. The specific material can be determined according to the overall product design requirements, and this application embodiment does not impose any limitations.

[0071] The specific implementation of other functional components can adopt the same implementation method as the aforementioned embodiments. Further details will not be provided here.

[0072] In a specific implementation, the n-type substrate 102 serves as the basis for epitaxial structure growth and can be an n-type group III nitride single-crystal substrate to ensure the stable formation of the laser epitaxial structure. Exemplarily, the n-type substrate 102 can be an n-type GaN single-crystal substrate, for example, but not limited to, formed using a metal-organic chemical vapor deposition (MOCVD) process. Please refer to Figure 4, which is a schematic diagram of another laser chip architecture provided in an embodiment of this application. To clearly illustrate the differences and connections between this embodiment and the schemes described in Figures 1 and 3 above, identical functional components or structures are indicated by the same labels in the figures.

[0073] As shown in Figure 4, each laser epitaxial structure 103 sequentially includes an n-type buffer layer 1031, an n-type confinement layer 1032, an n-side waveguide layer 1033, an active region 1034, a p-side waveguide layer 1035, a p-type confinement layer 1036, and a p-type contact layer 1037 along the second direction Y. For descriptive purposes, the first surface of each layer structure is defined as being located on the n-side, and the second surface as being located on the p-side.

[0074] The first surface of the first tunnel junction 104a is connected to the p-type contact layer 1037 of the first laser epitaxial structure 103a, and the second surface of the first tunnel junction 104a is connected to the n-type contact layer 105. The first surface of the second tunnel junction 104b is connected to the p-type contact layer 1037 of the second laser epitaxial structure 103b, and the second surface of the second tunnel junction 104b is connected to the n-type buffer layer 1031 of the first laser epitaxial structure 103a. The first surface of the third tunnel junction 104c is connected to the p-type contact layer 1037 of the third laser epitaxial structure 103c, and the second surface of the third tunnel junction 104c is connected to the n-type buffer layer 1031 of the second laser epitaxial structure 103b. Based on each tunnel junction, longitudinal electrical connectivity between the laser epitaxial structures is achieved.

[0075] The n-side electrode 101 is connected to the negative terminal (GND) of the driving circuit (not shown in the figure), and the p-side electrode 107 is connected to the positive terminal of the driving circuit. Under the action of the external driving circuit, current is injected into the active region 1034 of each laser epitaxial structure 103 through the pn junction. Electrons and holes recombine in the active region 1034 to release photons, and the photon wavelength is determined by the bandgap of the material. Under specific conditions, holes and electrons are in an excited state. When a photon encounters an excited electron, it causes it to transition to a lower energy state and releases two photons with the same frequency and phase direction, which are stimulated emission. Laser light can be realized when the gain generated by the stimulated emission process exceeds the loss and the number of photons in the optical resonant cavity reaches the threshold. The p-side waveguide layer 1035 and the n-side waveguide layer 1033 are located on the upper and lower sides of the active region 1034, respectively, to limit the propagation direction of light. The propagation of light in the active region 1034 is limited by the difference in refractive index. The p-type confinement layer 1036 is located outside the p-side waveguide layer 1035 (away from the active region), and the n-type confinement layer 1032 is located outside the n-side waveguide layer 1033 (away from the active region), used to further confine the propagation of light and prevent light leakage.

[0076] In a specific implementation, the active region 1034 may include one or more quantum well structures, which include a quantum well and quantum barriers located on both sides of the quantum well, thereby restricting the escape of electrons and holes from the quantum well.

[0077] The p-type contact layer 1037 is located above the p-type confinement layer 1036 and is used to achieve good electrical contact with the corresponding tunnel junction 104, thereby reducing contact resistance and ensuring efficient current injection into the active region 1034. Here, the materials of the p-type contact layer 1037, n-type confinement layer 1032, n-side waveguide layer 1033, active region 1034, p-side waveguide layer 1035, and p-type confinement layer 1036 can be group III nitrides. Specifically, they can include Al. x In y Ga (1-x-y) N, where x and y are both greater than or equal to 0 and less than or equal to 1, and satisfy: 0≤(x+y)≤1.

[0078] The n-type buffer layer 1031 serves as the bottom connection interface layer for each laser epitaxial structure 103. The n-type buffer layer 1031 improves epitaxial growth stress and ensures the crystal quality of the laser chip. In particular, it avoids the potential impact of the surface flatness of the tunnel junction 104 on the epitaxial growth accuracy.

[0079] For the laser epitaxial structure 103, based on the n-type confinement layer 1032, the n-side waveguide layer 1033, the active region 1034, the p-side waveguide layer 1035, and the p-type confinement layer 1036, other epitaxial structure layers can be configured according to actual needs.

[0080] In a specific implementation, an electron blocking layer (EBL) (not shown in the figure) can be provided between the p-type confinement layer 1036 and the p-type contact layer 1037 to further prevent electrons from overflowing from the active region 1034 to the p-type region, ensuring carrier confinement efficiency and improving the efficiency and performance of the laser.

[0081] In this embodiment, the lasing wavelengths of each laser epitaxial structure 103 can be the same or different. Preferably, for different wavelength configurations, the wavelength of the third laser epitaxial structure 103c is greater than or equal to the wavelength of the second laser epitaxial structure 103b, which is greater than or equal to the wavelength of the first laser epitaxial structure 103a. In other words, the wavelengths of each longitudinally cascaded laser epitaxial structure 103 can increase sequentially.

[0082] For example, three laser epitaxial structures 103 with different lasing wavelengths can correspond to the wavelengths of the three primary colors RGB, respectively. The wavelength of the third laser epitaxial structure 103c is 600nm-700nm (red), the wavelength of the second laser epitaxial structure 103b is 500nm-570nm (green), and the wavelength of the first laser epitaxial structure 103a is 400nm-470nm (blue). That is, from bottom to top, they are epitaxial structures corresponding to the three primary colors of blue, green, and red.

[0083] For example, three laser epitaxial structures 103 with different lasing wavelengths can each correspond to different wavelengths under any monochromatic RGB light. Taking the three-wavelength synthesis of green light as an example, the wavelength of the third laser epitaxial structure 103c is 530nm, the wavelength of the second laser epitaxial structure 103b is 525nm, and the wavelength of the first laser epitaxial structure 103a is 520nm, which is used to achieve the function of eliminating speckle. Furthermore, when the lasing wavelengths of each laser epitaxial structure 103 correspond to different wavelengths of the same primary color, the wavelength spacing is no greater than 10nm, which can obtain a better speckle elimination effect.

[0084] Of course, for other numbers of laser epitaxial structures 103, the wavelength can also be configured according to product design requirements. This application does not limit the embodiments.

[0085] It is understandable that the emission wavelength is mainly determined by the band gap of the active region material. In practical implementation, different wavelengths can be obtained by adjusting the 1034 band gap and stress of the active region. Specifically, the lasing wavelength can be precisely controlled by adjusting the material composition and thickness of the quantum well. For GaN substrates, this can be achieved by incorporating In components into a multi-quantum-well structure.

[0086] Here, the material of the multi-quantum well structure of the active region 1034 of each laser epitaxial structure can be a group III nitride.

[0087] Taking the three laser epitaxial structures 103 corresponding to the RGB three primary colors as an example, specifically, for the active region 1034 of the first laser epitaxial structure 103a, the quantum well material is Al. x1 In y1 GaN, the material for the quantum barrier is Al. x4 In y4 GaN, where 0≤x1≤1, 0≤y1≤1, 0≤x4≤1, 0≤y4≤1, and satisfying: 0≤(x1+y1)≤1, 0≤(x4+y4)≤1; for the active region 1034 of the second laser epitaxial structure 103b, the quantum well material is Al. x2 In y2 GaN, the material for the quantum barrier is Al. x5 In y5 GaN, where 0≤x2≤1, 0≤y2≤1, 0≤x5≤1, 0≤y5≤1, and satisfying: 0≤(x2+y2)≤1, 0≤(x5+y5)≤1; for the active region 1034 of the third laser epitaxial structure 103c, the quantum well material is Al. x3 In y3 GaN, the material for the quantum barrier is Al. x6 In y6 GaN, where 0≤x3≤1, 0≤y3≤1, 0≤x6≤1, 0≤y6≤1, and satisfying: 0≤(x3+y3)≤1, 0≤(x6+y6)≤1.

[0088] As a preferred value, y1≤y2≤y3≤0.5; x1<0.05; x2<0.05; x3<0.05; y4≤y5≤y6 <y1;x4≤x5≤x6≤0.2。

[0089] Furthermore, the waveguide layer (n-side waveguide layer 1033 and p-side waveguide layer 1035) of the first laser epitaxial structure 103a is made of Al. x7 In y7 GaN, where 0≤x7≤1, 0≤y7≤1, and satisfying: 0≤(x7+y7)≤1; the waveguide layer material of the second laser epitaxial structure 103b is Al. x8 In y8 GaN, where 0 ≤ x₈ ≤ 1, 0 ≤ y₈ ≤ 1, and satisfying: 0 ≤ (x₈ + y₈) ≤ 1; the waveguide layer material of the third laser epitaxial structure 103c is Al. x9 In y9 GaN, where 0≤x9≤1, 0≤y9≤1, and satisfy: 0≤(x9+y9)≤1.

[0090] As a preferred option, 0≤y7≤y8≤y9 <y1;x7<0.05;x8<0.05;x9<0.05。

[0091] Furthermore, the confinement layers (n-type confinement layer 1032 and p-type confinement layer 1036) of the first laser epitaxial structure 103a are made of Al. x10 In y10 GaN, where 0 ≤ x10 ≤ 1, 0 ≤ y10 ≤ 1, and satisfying: 0 ≤ (x10 + y10) ≤ 1; the confinement layer material of the second laser epitaxial structure 103b is Al. x11 In y11 GaN, where 0 ≤ x11 ≤ 1, 0 ≤ y11 ≤ 1, and satisfying: 0 ≤ (x11 + y11) ≤ 1; the confinement layer material of the third laser epitaxial structure 103c is Al. x12 In y12 GaN, where 0≤x12≤1, 0≤y12≤1, and satisfy: 0≤(x12+y12)≤1.

[0092] As a preferred value, x10≤x11≤x12≤0.2; y10<0.05; y11<0.05; y12<0.05.

[0093] For each tunnel junction 104 that achieves longitudinal electrical conduction, the material can be a group III nitride. Please refer to Figure 5, which is a schematic diagram of three tunnel junctions provided in the embodiments of this application.

[0094] As shown in Figure 5(a), the tunnel junction 104 includes an n-type doped layer 1041 and a p-type doped layer 1042, and the second surface of the p-type doped layer 1042 is in contact with the first surface of the n-type doped layer 1041.

[0095] In a specific implementation, the material of the n-type doped layer 1041 can be Al. x13 In y13 The material of Ga(1-x13-y13)N, p-type doped layer 1042 can be Al x14 In y14 Ga(1-x14-y14), where 0≤x13≤1, 0≤y13≤1, 0≤x14≤1, 0≤y14≤1, and satisfy: 0≤(x13+y13)≤1, 0≤(x14+y14)≤1.

[0096] To improve the tunneling probability, in one specific implementation, the tunneling effect can be achieved by increasing the doping concentration. The n-type doped layer 1041 can be a heavily n-type doped layer, and the dopant can be any one or more of silane (SiH4), germanane (GeH4), etc., with a doping concentration of 5 × 10⁻⁶. 18 / cm 3~2×10 21 / cm 3 The p-type doped layer 1042 can be a heavily n-type doped layer, and the dopant can be, but is not limited to, magnesia-dicenocene (Cp₂Mg), with a doping concentration of 5 × 10⁻⁶. 18 / cm 3 ~2×10 21 / cm 3 Preferably, the doping concentration of the p-type doped layer 1042 is not higher than the doping concentration of the n-type doped layer 1041; for example, but not limited to, when the dopant of the n-type doped layer 1041 is SiH4, the SiH4 doping concentration in the n-type doped layer 1041 is higher than the Cp2Mg doping concentration in the p-type doped layer 1042.

[0097] For example, in the tunnel junction 104 shown in Figure 5(a), the material of the n-type doped layer 1041 is heavily n-type doped GaN, and the material of the p-type doped layer 1042 is heavily p-type doped GaN.

[0098] In another specific implementation, the tunneling probability can be improved by band engineering by setting an intermediate layer 1043 between the n-type doped layer 1041 and the p-type doped layer 1042.

[0099] As shown in Figures 5(b) and (c), the tunnel junction 104 includes an n-type doped layer 1041, a p-type doped layer 1042, and an intermediate layer 1043. The material of the intermediate layer 1043 can be Al. x15 Ga (1-x15) N、In y15 Ga (1-y15) N, where 0≤x15≤1, 0≤y15≤1.

[0100] In specific implementations, when grown on a Ga polar facet, the intermediate layer 1043 is preferably InGaN as shown in Figure 5(b); when grown on an N polar facet, the intermediate layer 1043 is preferably AlGaN as shown in Figure 5(c) to ensure an increased probability of tunneling. In other specific implementations, the n-type doped layer 1041 is made of heavily n-type doped GaN, the p-type doped layer 1042 is made of heavily p-type doped GaN, and the intermediate layer 1043 is made of heavily p-type doped or undoped AlGaN.

[0101] Furthermore, the intermediate layer 1043 of each tunnel junction 104 can be any one or more of undoped, p-type doped, and n-type doped, with a doping concentration of less than 2 × 10⁻⁶. 21 / cm 3In the specific implementation, the intermediate layer 1043 adopts n-type doping or higher concentration of Si (silane) doping. On the one hand, it can neutralize the diffused Mg doping, and on the other hand, it helps to mitigate the band spikes formed at the interface due to stress / polarization electric field, improve tunneling efficiency, and thus reduce the overall resistance.

[0102] It should be noted that for the tunnel junction 104 without an intermediate layer shown in Figure 5(a), the compositions of the n-type doped layer 1041 and the p-type doped layer 1042 can both be configured with a gradual change. Taking Ga polarity as an example, the In composition in the InGaN of the p-type doped layer 1042 increases from 0 to a from the first to the second surface of the p-type doped layer 1042. Correspondingly, the In composition in the InGaN of the n-type doped layer 1041 decreases from a to 0 from the second to the first surface of the n-type doped layer 1041, where a < 0.4. Compared to the tunnel junction structure with an intermediate layer, this implementation of a gradual change in the compositions of the n-type doped layer 1041 and the p-type doped layer 1042 helps to mitigate the band spikes formed at the interface due to stress / polarization electric field, resulting in a flatter potential energy transformation, improved tunneling efficiency, and thus reduced overall resistance.

[0103] In practice, the epitaxial growth of the tunnel junction 104 can be achieved using one of the following methods: metal-organic chemical vapor deposition (MOCVD), reduced-pressure chemical vapor deposition (RPCVD), or molecular beam epitaxy (MBE). It should be understood that the heavily p-type doped layer 1042 needs to be in an activated state.

[0104] In other specific implementations, either RPCVD or MBE equipment can be used as the growth method for the intermediate layer 1043 and the n-type doped layer 1041. In this way, the p-type doped layer 1402 can be activated without additional annealing.

[0105] In other specific implementations, MOCVD equipment can be used as the growth method for the intermediate layer 1043 and the n-type doped layer 1041. The activation of the p-type doped layer 1042 can be achieved by any one or more of the following methods, including but not limited to in-furnace annealing, out-of-furnace lateral annealing, exposing part of the p-type doped layer surface, and MOCVD (growing the intermediate layer and n-type doped layer in an N2 atmosphere).

[0106] It should be noted that each tunneling joint 104 (first tunneling joint 104a, second tunneling joint 104b, and third tunneling joint 104c) can have the same structure or different structures. The specific structure can be determined according to the overall product design requirements, and this application does not limit it.

[0107] In the foregoing embodiments, a first tunneling junction 104a is provided on the top of the first laser epitaxial structure 103a. In other specific implementations, the first tunneling junction 104a may not be provided. Please refer to Figure 6, which is a schematic diagram of the architecture of another laser chip provided in this application embodiment. In order to clearly show the differences and connections between this embodiment and the foregoing embodiments, the same functional components or structures are shown with the same labels in the figure.

[0108] Compared with the aforementioned embodiments, the difference in the implementation of this application is that the top of the first laser epitaxial structure 103a is a p-type contact layer (1037), and the p-side electrode 107 is electrically connected to the p-type contact layer. Here, the p-side electrode 107 is a p-type electrode. While satisfying the tunneling efficiency, the embodiments of this application, based on the reduction of the number of tunnel junctions, can further reduce the overall device resistance and operating voltage, effectively improve thermal resistance and junction temperature, and thereby enhance device performance and reliability.

[0109] The specific implementation of other functional components can adopt the same implementation method as the aforementioned embodiments. Further details will not be provided here.

[0110] In the foregoing embodiments, waveguides 103-1 are all located on the p-side of the vertically stacked cascaded epitaxial structure. In other specific implementations, waveguides can also be formed on the n-side of the vertically stacked cascaded epitaxial structure. Please refer to Figure 7, which is a schematic diagram of the architecture of another laser chip provided by an embodiment of this application. In order to clearly show the differences and connections between this embodiment and the foregoing embodiments, the same functional components or structures are indicated by the same labels in the figure.

[0111] Compared with the aforementioned embodiments, the difference in the implementation of this application is that the waveguide 103-1 of the laser chip 100 is located on the n-side of the longitudinally stacked cascaded epitaxial structure, and the n-type substrate is removed. As shown in FIG7, the groove portion 103-2 extends from the side of the waveguide 103-1 to the top layer structure of the first laser epitaxial structure 103a, such as, but not limited to, the p-type confinement layer of the first laser epitaxial structure 103a. Accordingly, an insulating dielectric layer 106 is provided on both sides of the waveguide 103-1 and in the groove portion 103-2 to form effective insulation.

[0112] In this embodiment, the p-side electrode 107 (n-type electrode) can make full-surface contact with the top of the laser epitaxial structure through the n-type contact layer 105. By removing the insulating layer on the side of the path, the current injection area on the p-side is maximized, effectively reducing the p-side contact resistance and improving the heat dissipation path, thereby lowering the device operating voltage and thermal resistance. This further reduces the junction temperature and improves device performance and reliability. Furthermore, the design of waveguide 103-1 located on the n-side of the vertically stacked cascaded epitaxial structure avoids problems such as interlayer short circuits and cavity surface contamination, further improving overall device yield. Additionally, the design of waveguide 103-1 located on the n-side of the vertically stacked cascaded epitaxial structure further avoids material damage and resistance spikes that may occur when dry etching the p-side waveguide.

[0113] Here, the laser chip 100 does not retain the substrate with epitaxial growth structure, which can further improve the overall thermal resistance and junction temperature of the device, thereby improving the device performance and reliability.

[0114] In practice, the substrate can be removed using any process, including but not limited to laser lift-off, electrochemical etching, and mechanical lift-off. Furthermore, the second surface of the separated substrate can be polished so that it can still be reused for other epitaxial growth / chip fabrication, thus reasonably controlling chip manufacturing costs. The specific method can be determined based on actual process conditions, and this application does not impose limitations.

[0115] To form a stable and well-heat-dissipated n-side structure, an n-side heat dissipation substrate 110 may be included as a preferred embodiment. As shown in FIG7, the n-side heat dissipation substrate 110 is in full-surface contact with the n-side electrode 101. In this way, a reliable structural support can be formed based on the n-side heat dissipation substrate 110, while also providing n-side heat dissipation capability.

[0116] In specific implementations, the material of the n-side heat dissipation substrate 110 can be any one of Si substrate, AlN substrate, SiC substrate, diamond, etc. Preferably, the cleavage crystal orientation of the n-side heat dissipation substrate 110 matches the cleavage crystal orientation of the nitride to ensure cleavage yield, including but not limited to any one of 4H-SiC, 6H-SiC, Si(100), etc. The specific material can be determined according to the overall product design requirements, and this application embodiment does not limit it.

[0117] To further control the device junction temperature, a p-side heat dissipation substrate 108 that makes full contact with the p-side electrode 107 may also be included. Similarly, based on the laser chip 100 described in FIG7, it is suitable for single driving of multiple laser structures.

[0118] The specific implementation of other functional components can adopt the same implementation method as the aforementioned embodiments. Further details will not be provided here.

[0119] In the embodiments described in Figure 7 above, a first tunneling junction 104a is provided on the top of the first laser epitaxial structure 103a. In other specific implementations, the first tunneling junction 104a may not be provided. Please refer to Figure 8, which is a schematic diagram of another laser chip architecture provided by an embodiment of this application. In order to clearly show the differences and connections between this embodiment and the foregoing embodiments, the same functional components or structures are shown with the same labels in the figure.

[0120] Compared with the embodiment described in Figure 7 above, the difference in the implementation of this application is that the top of the first laser epitaxial structure 103a is a p-type contact layer (1037), and the p-side electrode 107 is electrically connected to the p-type contact layer. Here, the p-side electrode 107 is a p-type electrode. Based on satisfying the tunneling efficiency, the embodiment of this application, by reducing the number of tunnel junctions, can further reduce the overall device resistance and operating voltage, effectively improve thermal resistance and junction temperature, and thereby enhance device performance and reliability.

[0121] The specific implementation of other functional components can adopt the same implementation method as the aforementioned embodiments. Further details will not be provided here.

[0122] The laser chip 100 described in the foregoing embodiments is applicable to single-drive multiple laser structures. In other specific implementations, the vertically stacked cascaded epitaxial structure of the laser chip 100 adapted to RGB three primary colors can also be driven independently. Please refer to Figure 9, which is a schematic diagram of another laser chip provided in this application embodiment. To clearly illustrate the differences and connections between this embodiment and the foregoing embodiments, the same functional components or structures are shown with the same labels in the figure.

[0123] As shown in Figure 9, three p-side electrodes are provided for the three longitudinally stacked and cascaded laser epitaxial structures 103: a first p-type electrode 107a, a second p-type electrode 107b, and a third p-type electrode 107c.

[0124] Specifically, the first p-type electrode 107a is electrically connected to the waveguide 103-1 of the three vertically stacked laser epitaxial structures 103. More specifically, the first p-type electrode 107a can be connected to the first laser epitaxial structure 103a via a first p-type process contact layer 109a.

[0125] In the first direction X, the second laser epitaxial structure 103b extends laterally to the side of the first laser epitaxial structure 103a, and a second waveguide 103-1b is formed on the extended portion of the second laser epitaxial structure 103b. The second p-type electrode 107b is electrically connected to the second waveguide 103-1b. Specifically, the second p-type electrode 107b can be connected to the second laser epitaxial structure 103b through a second p-type process contact layer 109b.

[0126] In the first direction X, the third laser epitaxial structure 103c extends laterally to the side of the second laser epitaxial structure 103b, and a third waveguide 103-1c is formed on the extended portion of the third laser epitaxial structure 103c. The third p-type electrode 107c is electrically connected to the third waveguide 103-1c. Specifically, the third p-type electrode 107c can be connected to the third laser epitaxial structure 103c through a third p-type process contact layer 109c.

[0127] Of course, the above-described independent driving architecture can also be used for vertically stacked and cascaded laser epitaxial structures, such as, but not limited to, vertically stacked and cascaded two, four, or five laser epitaxial structures. Overall, except for the first laser epitaxial structure 103a located at the top, the other laser epitaxial structures (the second laser epitaxial structure 103b and the third laser epitaxial structure 103c) extend laterally in the first direction X and form independent waveguides, and each independent waveguide is correspondingly provided with a p-side electrode.

[0128] As a preferred embodiment, both the third laser epitaxial structure 103c and the second laser epitaxial structure 103b extend laterally to the same side, resulting in a relatively compact structural layout and good manufacturability.

[0129] In this embodiment, the three laser epitaxial structures 103 share a common n-side electrode 101. Accordingly, the first p-type electrode 107a can drive the three laser epitaxial structures 103 (first laser epitaxial structure 103a, second laser epitaxial structure 103b, and third laser epitaxial structure 103c), the second p-type electrode 107b can drive the second laser epitaxial structure 103b and the third laser epitaxial structure 103c, and the third p-type electrode 107c can drive the third laser epitaxial structure 103c. Thus, for different application scenarios, corresponding driving currents can be applied to the first p-type electrode 107a, the second p-type electrode 107b, and the third p-type electrode 107c respectively to achieve excitation wavelengths in different color gamuts.

[0130] Here, the dimensions of waveguide 103-1, the second waveguide 103-1b, and the third waveguide 103-1c can be determined according to the overall product design requirements. For example, but not limited to, the width W of each waveguide is 1µm to 100µm, the length L is 100µm to 2000µm, and the height H is 0.2µm to 2000nm. The specific dimensions can be determined according to the overall product design requirements, and this embodiment does not impose any limitations.

[0131] In the specific implementation, the three p-type electrodes (first p-type electrode 107a, second p-type electrode 107b, and third p-type electrode 107c) are not electrically conductive to achieve individual driving of each laser epitaxial structure 103. Similarly, insulating dielectric layers 106 are provided on both sides of each waveguide (waveguide 103-1, second waveguide 103-1b, and third waveguide 103-1c) and in the groove portion 103-2 to form lateral insulation between the waveguide structures.

[0132] Meanwhile, the laser chip 100 may also include a p-side heat dissipation substrate 108, the first surface of which is bonded to the first p-type electrode 107a, the second p-type electrode 107b, and the third p-type electrode 107c to improve heat dissipation. The p-side heat dissipation substrate 108 can achieve physical isolation of the first p-type electrode 107a, the second p-type electrode 107b, and the third p-type electrode 107c through structural design, thereby reliably enabling individual driving of each laser.

[0133] In specific implementations, the first p-type process contact layer 109a, the second p-type process contact layer 109b, and the third p-type process contact layer 109c can all be annealed to form ohmic contacts.

[0134] Based on the laser chip 100 described in Figure 9, for the vertically stacked cascaded epitaxial structure adapted to RGB three primary colors, the color gamut can be controlled more precisely by driving it separately, while the device size and cost can be reasonably controlled.

[0135] In other implementations, for two laser epitaxial structures stacked sequentially, or for multiple other laser epitaxial structures stacked sequentially, the aforementioned architecture of independently driven structures can also be used. That is, the other laser epitaxial structures 103 besides the top laser epitaxial structure 103 extend laterally in the first direction X to form independent waveguides (second waveguide 103-1b and third waveguide 103-1c), and each independent waveguide is correspondingly provided with p-type electrodes (second p-type electrode 107b and third p-type electrode 107c). The specific implementation can be determined according to product design needs, and this application embodiment does not limit the specific implementation.

[0136] Of course, for three or more laser epitaxial structures stacked and cascaded in sequence, preferably, the other laser epitaxial structures 103, except for the top laser epitaxial structure 103, extend laterally to the same side in the first direction X. Further details will not be elaborated here.

[0137] The specific implementation of other functional components can adopt the same implementation method as the aforementioned embodiments. Further details will not be provided here.

[0138] The laser chip described in Figure 9 above can be formed into a laser epitaxial structure that can be driven independently through multiple selected area epitaxy methods. Please refer to Figure 10, which is a simplified process flow diagram of a laser epitaxial structure provided in an embodiment of this application. The process steps of multiple selected area epitaxial growth are illustrated by three laser epitaxial structures 103.

[0139] In step S1001, on the n-type substrate 102, functional layers corresponding to the three laser epitaxial structures (first laser epitaxial structure 103a, second laser epitaxial structure 103b, and third laser epitaxial structure 103c) and tunnel junctions (second tunnel junction 104b and third tunnel junction 104c) are grown layer by layer to form a vertically stacked cascaded structure. Here, in the first direction X, the size of the vertically stacked cascaded structure formed in step S1001 is consistent with the maximum size of the laterally extending laser epitaxial structure.

[0140] In practice, the growth of laser epitaxial structures can be achieved using one of the following methods: metal-organic chemical vapor deposition (MOCVD), atmospheric pressure chemical vapor deposition (APCVD), or molecular beam epitaxy (MBE).

[0141] Step S1002: Remove material to form groove 103-2.

[0142] In a specific implementation, based on the longitudinally stacked cascaded structure formed in step S1001, the material on both sides is removed to form a groove portion 103-2. Here, after removing the material to form the groove portion 103-2, the structural layer of the third laser epitaxial structure 103c near the n-type substrate 102 can be retained, for example, but not limited to, the n-type buffer layer 1031 and / or the n-type contact layer can be retained.

[0143] In practice, the removal methods include, but are limited to, any one of the material removal processes such as dry etching, wet etching, and electrochemical etching.

[0144] Dry etching includes, but is not limited to, any one of the following processes: inductively coupled plasma (ICP), reactive ion etching (RIE), or ion beam etching (IBE). Wet etching and electrochemical etching use etching reagents including alkaline or acidic solvents. For example, alkaline solvents include, but are limited to, any one or a combination of two or more of potassium hydroxide (KOH), sodium hydroxide (NaOH), and tetramethylammonium hydroxide (TMAH); for example, acidic solvents include, but are not limited to, any one or a combination of two of phosphoric acid (H3PO4), hydrofluoric acid (HF), and oxalic acid (HO2C–CO2H).

[0145] Step S1003: Remove a portion of the first laser epitaxial structure 103a, and retain the portion of the first laser epitaxial structure 103a near the groove 103-2 on one side.

[0146] In a specific implementation, the first laser epitaxial structure 103a and part of the second tunnel junction 104b are etched, while the portion of the first laser epitaxial structure 103a near the groove 103-2 on one side is retained. In this state, the second laser epitaxial structure 103b and the third laser epitaxial structure 103c extend laterally from the first laser epitaxial structure 103a.

[0147] The specific etching process can be the same as step S1002. It will not be described in detail here.

[0148] Step S1004: Remove a portion of the second laser epitaxial structure 103b, and retain the portion of the second laser epitaxial structure 103b near the groove 103-2 (first laser epitaxial structure 103a).

[0149] In the specific implementation, the second laser epitaxial structure 103b and part of the third tunnel junction 104c are etched, while the portion of the second laser epitaxial structure 103b near the groove 103-2 on one side is retained. In this state, the third laser epitaxial structure 103c extends laterally beyond the second laser epitaxial structure 103b.

[0150] The specific etching process can be the same as step S1002. It will not be described in detail here.

[0151] It is understood that the structure after the above etching process can be surface cleaned. Here, surface cleaning includes, but is not limited to, using any one or more of inorganic and organic solvents. Exemplarily, inorganic solvents include, but are limited to, one or more of hydrofluoric acid (HF), phosphoric acid (H3PO4), sulfuric acid (H2SO4), and BOE (buffer oxide etch). Exemplarily, organic solvents include, but are limited to, any one or more of acetone (CH3COCH3), isopropanol (C3H8O), and ethanol (C2H6O).

[0152] In practice, depending on the actual process conditions, for processes using organic solvents for cleaning, the cleaning operation can be carried out at a temperature below 150°C.

[0153] In step S1005, a first p-type process contact layer 109a, a second p-type process contact layer 109b, and a third p-type process contact layer 109c are formed on the top of the retained first laser epitaxial structure 103a, the top of the second laser epitaxial structure 103b, and the top of the laterally extended first laser epitaxial structure 103a, respectively.

[0154] The selection of growth equipment for the first p-type process contact layer 109a, the second p-type process contact layer 109b, and the third p-type process contact layer 109c can be the same as in step S1001. This will not be elaborated further here.

[0155] Step S1006: Remove material to form a waveguide.

[0156] In practice, waveguide 103-1, second waveguide 103-1b, and third waveguide 103-1c can be formed using an etching process.

[0157] The specific etching process can be the same as step S1002. It will not be described in detail here.

[0158] Step S1007: Forming the insulating dielectric layer 106.

[0159] In a specific implementation, an insulating dielectric layer 106 is deposited on both sides of each waveguide (waveguide 103-1, second waveguide 103-1b and third waveguide 103-1c) and in the groove portion 103-2 to form lateral insulation between each waveguide.

[0160] Based on the structural pattern obtained in step S1007, further steps can be performed to implement other functional structures of the laser chip, such as, but not limited to, thickening the electrodes on the p-side and forming a p-side heat dissipation substrate 108. This can be achieved using existing technologies, which will not be elaborated here.

[0161] The laser chips described in the foregoing embodiments have laser epitaxial structures 103 vertically stacked and cascaded on an n-type substrate. In other possible implementations, functional layers (not shown in the figures) of each laser epitaxial structure 103 can also be deposited on a p-type substrate. That is, the p-type electrode is located on the side of the substrate away from the laser epitaxial structure in the second direction, and the n-type electrode is located on the side of the laser epitaxial structure away from the substrate in the second direction.

[0162] It should be noted that at least two vertically stacked and cascaded laser epitaxial structures 103 can be deposited on the p-type substrate, and the specific fabrication process can be consistent with the aforementioned embodiments. Further details will not be provided here.

[0163] Based on the aforementioned laser chip, this application also provides a laser module. Please refer to Figure 11, which is a schematic diagram of the laser module provided in this application embodiment.

[0164] The laser module 1000a includes a laser chip 100 as described above, a circuit board 200, a housing 300, a reflector 400, a sapphire cover plate 500, and a collimating lens array 600. As shown in Figure 11, the laser chip 100 can be encapsulated within the housing 300 mounted on the circuit board 200. The circuit board 200 can provide the laser chip 100 with stable current drive, modulation signals, and temperature control to generate laser light. A reflector is disposed within the housing 300 to adjust the beam propagation direction of the laser. The sapphire cover plate 500 is sealed to the housing 300 to form a hermetically sealed device. The collimating lens array 600 is stacked on the sapphire cover plate 500 to ensure beam quality.

[0165] Based on the aforementioned laser chip, this laser module also has the ability to reduce cost and size, effectively improve speckle in projection scenarios, and avoid problems such as reduced light efficiency, increased heat dissipation, decreased efficiency, and excessively large substrate that may result from increasing power by increasing operating current.

[0166] It should be understood that the other functional components of the laser module 1000a can be implemented using existing technologies. These will not be elaborated upon here.

[0167] Based on the aforementioned laser chip, this application embodiment also provides an optical module. Please refer to Figure 12, which is a schematic diagram of the optical module provided in this application embodiment.

[0168] The optical module 1000b includes a driver chip 200b and a laser chip 100 as described above. The output terminal of the driver chip 200b is electrically connected to the laser chip 100. The driver chip 200b is used to inject electrons into the electrode layer of the laser chip 100.

[0169] In a specific implementation, the driver chip 200b and the laser chip 100 are mounted on the same substrate (not shown in the figure). In other implementations, the driver chip 200b and the laser chip 100 are packaged separately; for example, the driver chip is packaged in a driver module, and the laser chip is packaged in a laser device. Based on the aforementioned laser chip, this optical module also has the advantages of reducing cost and size, effectively improving speckle in the projection scene, and avoiding the problems of reduced luminous efficiency, increased heat dissipation, decreased efficiency, and excessively large substrate that may result from increasing power by increasing operating current.

[0170] Based on the aforementioned optical module, this application embodiment also provides a laser device, which includes an optical component and the optical module described in FIG11. The optical component is used to adjust the optical parameters (not shown in the figure) of the laser output by the optical module. The optical parameters of the laser include, but are not limited to, at least one of the following: laser propagation direction, spot size, polarization state, intensity, and wavelength. Based on the aforementioned laser chip, this optical module also has the advantages of reducing cost and size, effectively improving speckle in projection scenes, and avoiding the problems of reduced luminous efficiency, increased heat dissipation, decreased efficiency, and excessively large substrate that may result from increasing power by increasing operating current.

[0171] It should be understood that other functional components of this laser device can be implemented using existing technologies. These will not be elaborated upon here.

[0172] Furthermore, the ordinal numbers "first" and "second," etc., used herein are only for describing the composition or structure of the same function in the technical solution. It is understood that the use of the aforementioned ordinal numbers does not constitute a limitation on the understanding of the technical solution for which protection is sought in this application.

[0173] The above are merely preferred embodiments of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A laser chip, characterized in that, The laser chip includes an n-side electrode, a substrate, a laser epitaxial structure, and a p-side electrode. At least two laser epitaxial structures are configured, stacked sequentially along a second direction on the substrate, with a tunnel junction between adjacent laser epitaxial structures. One of the n-side electrode and the p-side electrode is located on the side of the substrate away from the laser epitaxial structure in the second direction, and the other is located on the side of the laser epitaxial structure away from the substrate in the second stacking direction. The second direction is the direction intersecting the plane containing the substrate.

2. The laser chip according to claim 1, characterized in that, At least two of the laser epitaxial structures have the same or different lasing wavelengths.

3. The laser chip according to claim 2, characterized in that, The epitaxial structures of the lasers, each with a different lasing wavelength, are arranged in a manner that increases sequentially along the second direction.

4. The laser chip according to any one of claims 1 to 3, characterized in that, The laser epitaxial structure is configured as three, namely a third laser epitaxial structure, a second laser epitaxial structure and a first laser epitaxial structure stacked and cascaded in sequence; the lasing wavelength of the third laser epitaxial structure is 600nm to 700nm, the lasing wavelength of the second laser epitaxial structure is 500nm to 570nm, and the lasing wavelength of the first laser epitaxial structure is 400-470nm.

5. The laser chip according to claims 1 to 3, characterized in that, The lasing wavelengths of each of the laser epitaxial structures correspond to the same primary color, and the lasing wavelength spacing between each of the laser epitaxial structures is no greater than 10 nm.

6. The laser chip according to any one of claims 1 to 5, characterized in that, The substrate, the laser epitaxial structure, and the tunnel junction are made of group III nitrides.

7. The laser chip according to any one of claims 1 or 6, characterized in that, The substrate is an n-type substrate, and the n-side electrode is an n-type electrode electrically connected to the n-type substrate. The laser epitaxial structure includes, along the second direction, an n-type buffer layer, an n-type confinement layer, an n-side waveguide layer, an active region, a p-side waveguide layer, a p-type confinement layer, and a p-type contact layer. The p-side electrode is electrically connected to the p-type contact layer of the laser epitaxial structure located at the top of the stack.

8. The laser chip according to claim 7, characterized in that, There is a tunnel junction between the p-side electrode and the laser epitaxial structure located on top of the stack.

9. The laser chip according to any one of claims 1 to 8, characterized in that, The waveguide of the laser chip is located on the p-side, and the laser chip also includes a p-side heat dissipation substrate, which is in full-surface contact with the p-side electrode.

10. The laser chip according to claim 9, characterized in that, In at least two laser epitaxial structures that are stacked and cascaded in sequence, the other laser epitaxial structures, except for the top laser epitaxial structure, extend laterally in a first direction to form independent waveguides, and the independent waveguides are respectively provided with p-side electrodes.

11. The laser chip according to any one of claims 1 to 8, characterized in that, The waveguide of the laser chip is located on the n-side, and the substrate of the laser chip is removed. The laser chip also includes a p-side heat dissipation substrate and an n-side heat dissipation substrate. The p-side heat dissipation substrate is in full-surface contact with the p-side electrode, and the n-side heat dissipation substrate is in full-surface contact with the n-side electrode.

12. The laser chip according to claim 4, characterized in that, The active region of each of the laser epitaxial structures includes one or more quantum well structures; The quantum well material of the active region of the first laser epitaxial structure is Al. x1 In y1 GaN, the quantum barrier material is Al x4 In y4 GaN, where 0≤x1≤1, 0≤y1≤1, 0≤x4≤1, 0≤y4≤1, and satisfying: 0≤(x1+y1)≤1, 0≤(x4+y4)≤1; The quantum well material of the active region of the second laser epitaxial structure is Al. x2 In y2 GaN, the quantum barrier material is Al x5 In y5 GaN, where 0≤x2≤1, 0≤y2≤1, 0≤x5≤1, 0≤y5≤1, and satisfying: 0≤(x2+y2)≤1, 0≤(x5+y5)≤1; The quantum well material of the active region of the third laser epitaxial structure is Al. x3 In y3 GaN, the material for the quantum barrier is Al. x6 In y6 GaN, where 0≤x3≤1, 0≤y3≤1, 0≤x6≤1, 0≤y6≤1, and satisfying: 0≤(x3+y3)≤1, 0≤(x6+y6)≤1.

13. The laser chip according to claim 12, characterized in that, y1≤y2≤y3≤0.5; x1<0.05; x2<0.05; x3<0.05; y4≤y5≤y6 <y1;x4≤x5≤x6≤0.2。 14. The laser chip according to claim 4, 12 or 13, characterized in that, The waveguide layer of the first laser epitaxial structure is made of Al. x7 In y7 GaN, where 0 ≤ x7 ≤ 1, 0 ≤ y7 ≤ 1, and satisfying: 0 ≤ (x7 + y7) ≤ 1; the waveguide layer material of the second laser epitaxial structure is Al. x8 In y8 GaN, where 0 ≤ x8 ≤ 1, 0 ≤ y8 ≤ 1, and satisfying: 0 ≤ (x8 + y8) ≤ 1; the waveguide layer material of the third laser epitaxial structure is Al. x9 In y9 GaN, where 0≤x9≤1, 0≤y9≤1, and satisfy: 0≤(x9+y9)≤1.

15. The laser chip according to claim 14, characterized in that, 0≤y7≤y8≤y9 <y1;x7<0.05;x8<0.05;x9<0.05。 16. The laser chip according to any one of claims 4, 12 to 15, characterized in that, The confinement layer of the first laser epitaxial structure is made of Al. x10 In y10 GaN, where 0 ≤ x10 ≤ 1, 0 ≤ y10 ≤ 1, and satisfying: 0 ≤ (x10 + y10) ≤ 1; the confinement layer material of the second laser epitaxial structure is Al. x11 In y11 GaN, where 0 ≤ x11 ≤ 1, 0 ≤ y11 ≤ 1, and satisfying: 0 ≤ (x11 + y11) ≤ 1; the confinement layer material of the third laser epitaxial structure is Al. x12 In y12 GaN, where 0≤x12≤1, 0≤y12≤1, and satisfy: 0≤(x12+y12)≤1.

17. The laser chip according to claim 16, characterized in that, x10≤x11≤x12≤0.2; y10<0.05; y11<0.05; y12<0.

05.

18. The laser chip according to any one of claims 1 to 17, characterized in that, The tunnel junction includes an n-type doped layer and a p-type doped layer, wherein the material of the n-type doped layer is Al. x13 In y13 Ga(1-x13-y13)N, wherein the p-type doped layer is made of Al. x14 In y14 Ga (1- x14-y14) , where 0≤x13≤1, 0≤y13≤1, 0≤x14≤1, 0≤y14≤1, and satisfy: 0≤(x13+y13)≤1, 0≤(x14+y14)≤1.

19. The laser chip according to claim 18, characterized in that, The dopant of the n-type doped layer is at least one of silane and germanane, and the doping concentration is 5 × 10⁻⁶. 18 / cm 3 ~2×10 21 / cm 3 The dopant of the p-type doped layer is magnesium pyrocene, and the doping concentration is 5 × 10⁻⁶. 18 / cm 3 ~2×10 21 / cm 3 .

20. The laser chip according to claim 19, characterized in that, The dopant of the n-type doped layer is silane, and the doping concentration of the silane is higher than that of the magnesium diacene.

21. The laser chip according to any one of claims 18 to 20, characterized in that, The tunnel junction further includes an intermediate layer located between the n-type doped layer and the p-type doped layer, the intermediate layer being made of Al. x15 Ga (1-x15) N、In y15 Ga (1-y15) N, where 0≤x15≤1, 0≤y15≤1.

22. The laser chip according to claim 21, characterized in that, The intermediate layer is any one or more of undoped, p-type doped, and n-type doped, and the doping concentration is less than 2 × 10⁻⁶. 21 / cm 3 .

23. The laser chip according to claim 22, characterized in that, The intermediate layer is n-type doped, and the dopant is silane.

24. A laser module, characterized in that, The laser module includes a laser chip, a circuit board, a reflector, and a housing. The laser chip is the laser chip according to any one of claims 1 to 23. The housing is disposed on the circuit board, and the compatible laser chip and the reflector are located inside the housing.

25. An optical module, characterized in that, The optical module includes a driver chip and a laser chip, wherein the laser chip is the laser chip according to any one of claims 1 to 23, and the output terminal of the driver chip is electrically connected to the laser chip.

26. A laser device, characterized in that, The laser device includes optical components and an optical module, wherein the optical module is the optical module described in claim 25, and the optical components are used to adjust the optical parameters of the laser output by the optical module.

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