High-efficiency heat-conducting semiconductor laser element and heat dissipation method thereof

Abstract

The invention relates to a semiconductor photoelectric device technology, and discloses an efficient heat-conducting semiconductor laser element and a heat dissipation method thereof. The element comprises a substrate, a lower limiting layer, an active region, an upper limiting layer and a heat dissipation structure, wherein an efficient heat conduction layer is arranged between the upper limiting layer and the heat dissipation structure. The heat conduction layer takes a diamond film with a high heat conductivity coefficient as a substrate, is doped with boron atoms with a specific concentration, and is provided with a nanoscale pore channel array. The structure can effectively capture and conduct heat generated by an active area, heat is efficiently exported through high thermal conductivity of diamond, boron-doped enhanced electron-phonon coupling and a directional phonon transport effect of the nanopore array, and the working temperature of the device is remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to the manufacturing and thermal management technology of semiconductor optoelectronic devices, and particularly to a high-efficiency thermally conductive semiconductor laser element with high heat dissipation capability and its heat dissipation method. Background Technology

[0002] Semiconductor laser components, as a core component of optoelectronic technology, have found wide application in fields such as fiber optic communication, laser processing, medical aesthetics, LiDAR, and scientific research due to their advantages of small size, high efficiency, and long lifespan. With the continuous upgrading of application demands, the market is placing higher requirements on the output power, power density, and integration of semiconductor laser components. However, increased power inevitably brings with it more severe thermal effects.

[0003] During the operation of semiconductor laser devices, the injected electrical energy is not completely converted into light energy; a significant portion of the energy is dissipated as heat. The main sources of heat include nonradiative recombination of charge carriers (electrons and holes) in the active region and Joule heating generated by the bulk resistance and contact resistance of the device materials. If this heat cannot be effectively and promptly removed from the device's interior, especially from the active region—the core heat-generating area—the temperature of the active region and its surrounding area will rise sharply.

[0004] Increased local temperature can trigger a series of negative effects, severely impacting the performance, reliability, and lifespan of semiconductor laser devices. Specifically: 1) Performance degradation: Increased temperature leads to a reduction in the material's bandgap, causing a redshift in the output laser wavelength, while also reducing internal quantum efficiency, resulting in decreased output power and increased threshold current; 2) Reduced reliability and lifespan: Continuous high-temperature operation accelerates material aging, defect proliferation, and electrode degradation, significantly shortening the device's lifespan; 3) Catastrophic optical damage (COD): When the active region temperature is too high, especially at the cleaved cavity surface, the material's absorption of laser light increases dramatically, creating positive feedback that leads to localized instantaneous melting, causing irreversible and permanent damage to the device.

[0005] To address the aforementioned heat dissipation issues, existing technologies primarily employ two strategies: passive and active cooling. Passive cooling, such as using heat sinks made of high thermal conductivity materials like copper, aluminum nitride (AlN), or diamond, removes heat from the chip through thermal conduction. However, its efficiency is limited by two bottlenecks: first, the relatively low thermal conductivity of the semiconductor materials themselves (such as GaAs and InP) forms the first barrier to heat dissipation from the active region; second, the high interfacial thermal resistance (ITR) between the chip and the heat sink hinders effective heat transfer. Active cooling technologies, such as using thermoelectric coolers (TECs) or microchannel liquid cooling, offer stronger heat dissipation capabilities, but generally suffer from problems such as system complexity, large size, high energy consumption, and reliability concerns.

[0006] In summary, most existing heat dissipation technologies for semiconductor laser devices focus on dissipating heat already conducted to the outside of the chip, failing to fundamentally address the bottleneck issue of heat conduction within the chip, particularly along the critical path from the heat source (active region) to the heat dissipation interface. Therefore, there is an urgent need in this field for an innovative heat dissipation solution that can significantly reduce the thermal resistance from the active region to the heat dissipation structure, fundamentally improve heat dissipation efficiency, and possess a relatively simple structure and high reliability. Summary of the Invention

[0007] The purpose of this invention is to overcome the technical defects of existing semiconductor laser devices, such as heat accumulation in the active region due to poor internal heat conduction, which affects device performance and reliability. This invention provides a high-efficiency heat-conducting semiconductor laser device and its heat dissipation method that can optimize the heat conduction path from the inside of the device structure and significantly reduce the total thermal resistance from the active region to the external heat dissipation structure.

[0008] To achieve the above objectives, a first aspect of the present invention provides a highly efficient thermally conductive semiconductor laser element, comprising: Substrate; A lower confinement layer, an active region, and an upper confinement layer are sequentially disposed on the substrate; and A heat dissipation structure is disposed opposite to the upper limiting layer; The feature is that a high-efficiency thermally conductive layer is disposed between the upper limiting layer and the heat dissipation structure, the high-efficiency thermally conductive layer comprising: Diamond films with high thermal conductivity as a matrix material; Boron atoms are doped into the diamond film, and the doping concentration of the boron atoms is 1×10⁻⁶. 18 cm -3 Up to 1×10 20 cm -3; and a nanoscale pore array formed in the diamond film and extending through its thickness direction, the nanoscale pore array having a pore size of 5 nm to 20 nm and a pore density of 10. 10 cm -2 Up to 10 12 cm -2 .

[0009] As a preferred technical solution, the thickness of the high-efficiency thermal conductive layer is 10nm to 50nm.

[0010] Preferably, the boron atom doping concentration is gradient-distributed along the thickness direction of the high-efficiency thermally conductive layer. More preferably, the boron atom doping concentration gradually decreases from the side closer to the active region to the side closer to the heat dissipation structure. More preferably, on the side closer to the active region, the boron atom doping concentration is 1 × 10⁻⁶. 20 cm -3 In the middle region of the high-efficiency thermally conductive layer, the doping concentration is 5×10⁻⁶. 19 cm -3 On the side closest to the heat dissipation structure, the doping concentration is 1×10⁻⁶. 19 cm -3 .

[0011] Preferably, the channels in the nanoscale pore array are arranged in a hexagonal close-packed structure, and the axial direction of the channels forms an angle of 15° to 30° with the heat flow direction from the active region to the heat dissipation structure.

[0012] Preferably, the inner surface of the nanoscale pore array is hydrogen-terminated to form a carbon-hydrogen bonded surface.

[0013] Preferably, a transition layer with a thickness of 2nm to 5nm is provided between the upper confining layer and the high-efficiency thermal conductive layer, the transition layer being used to alleviate the lattice mismatch between the upper confining layer and the high-efficiency thermal conductive layer.

[0014] Preferably, a nanoscale metal bonding layer is provided between the high-efficiency thermally conductive layer and the heat dissipation structure, and the metal bonding layer is used to realize a low thermal resistance electrical and thermal connection between the high-efficiency thermally conductive layer and the heat dissipation structure.

[0015] Preferably, the heat dissipation structure is a copper-based diamond composite heat sink or a microchannel liquid-cooled heat sink.

[0016] A second aspect of the present invention provides a heat dissipation method for a semiconductor laser element, which is applied to a high-efficiency thermally conductive semiconductor laser element as described in any of the preceding claims. The method includes the following steps: S1: Heat generation step, when the semiconductor laser element is working, heat is generated in the active region due to nonradiative recombination of charge carriers and the Joule effect; S2: Heat capture step, wherein the high-efficiency thermally conductive layer efficiently captures heat transferred from the active region via the upper confinement layer through phonon coupling effect, enhanced electron-phonon interaction and reduced interfacial thermal resistance; S3: Heat conduction step, whereby the captured heat is efficiently conducted to the heat dissipation structure through the directional heat conduction path constructed by the nanoscale pore array in the high-efficiency thermal conductive layer, with an equivalent thermal conductivity of up to 2000 W / (m·K) to 3000 W / (m·K); S4: Heat dissipation step, wherein the heat dissipation structure rapidly dissipates the received heat into the surrounding environment.

[0017] As a preferred technical solution, in the heat generation step, the heat generated by nonradiative recombination of charge carriers accounts for 60% to 70% of the total heat, and the heat generated by Joule heating accounts for 30% to 40% of the total heat; and / or, in the heat capture step, the interfacial thermal resistance between the high-efficiency thermally conductive layer and the upper confining layer or heat dissipation structure is less than 1×10⁻⁶. - 8 m 2 ·K / W.

[0018] Compared with existing technologies, the technical solution provided by this invention fundamentally solves the bottleneck problem of heat conduction from the active region to the outside within the chip by innovatively integrating a specially designed composite structure high-efficiency thermal conductive layer inside the semiconductor laser element. This high-efficiency thermal conductive layer utilizes the high intrinsic thermal conductivity of diamond thin film, the electron-phonon coupling enhanced by boron doping, and the directional phonon transport effect of the nanoscale channel array. The synergistic effect of these three factors achieves extremely high equivalent thermal conductivity, thereby efficiently dissipating heat generated in the active region and significantly reducing the steady-state operating temperature of the device. The resulting benefits include a comprehensive improvement in the optoelectronic performance of the device, including increased stability of the output wavelength, reduced threshold current, improved slope efficiency, and enhanced resistance to catastrophic optical damage (COD). Simultaneously, the low-temperature operating environment delays material aging, significantly extending the reliability and lifespan of the device. Furthermore, as a compact chip-level heat dissipation structure, this solution facilitates device miniaturization and high-density integration, and is expected to simplify or even replace complex external active cooling systems in specific applications, thereby reducing the overall module cost, energy consumption, and complexity. Attached Figure Description

[0019] Figure 1 This is a flowchart of the heat dissipation process for semiconductor laser components. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Furthermore, the term "and / or" used in the embodiments of the present invention indicates that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone.

[0022] Example 1 This embodiment provides a specific implementation of a high-efficiency thermally conductive semiconductor laser element and its heat dissipation method. The overall layered structure of the element, from bottom to top, includes: a substrate, a lower confinement layer, an active region, an upper confinement layer, a high-efficiency thermally conductive layer, and a heat dissipation structure.

[0023] I. Device Structure and Fabrication (a) Semiconductor epitaxial structure In this embodiment, the substrate is an n-type heavily doped (100) oriented GaAs single crystal substrate. Subsequent functional layers are epitaxially grown on the substrate using metal-organic chemical vapor deposition (MOCVD). The lower confinement layer is an n-type Al. 0.3 Ga 0.7 As layer. The active region uses In... 0.2 Ga 0.8 As / Al 0.2 Ga 0.8 As a multi-quantum-well structure, the designed emission wavelength is 860 nm. During operation, the active region is the main source of heat generation, with non-radiative recombination accounting for approximately 65% ​​of the total heat, and the remaining 35% being Joule heat. The upper confinement layer is p-type Al. 0.3 Ga 0.7 As layer. The lower confinement layer and the upper confinement layer together form a double heterojunction, which effectively confines the charge carriers and optical field within the active region.

[0024] (ii) High-efficiency thermal conductive layer The high-efficiency thermally conductive layer is the core of this embodiment. It is integrated on top of the upper confinement layer, and its total thickness is precisely controlled at 30nm. Its detailed structure and fabrication process are as follows: First, in the p-type Al of the upper confinement layer 0.3 Ga 0.7 A 3 nm thick transition layer was grown on the As surface. This transition layer was grown in situ using MOCVD, and its Al composition smoothly transitioned from 30% to 0% (i.e., from Al...). 0.3 Ga 0.7As is gradually transformed into GaAs to effectively alleviate the lattice mismatch between the subsequently grown diamond and AlGaAs.

[0025] Next, the main body of the high-efficiency thermally conductive layer is prepared. This main body consists of a diamond film, doped boron atoms, and a nanoscale pore array.

[0026] Growth of diamond film: A 30 nm thick nanocrystalline diamond film was grown on the surface of the transition layer using hot filament chemical vapor deposition (HFCVD). This film possesses high-purity diamond sp. 3 With its bonded structure and strong (111) crystal plane preferred orientation, its intrinsic thermal conductivity can reach 2200 W / (m·K).

[0027] Gradient doping of boron atoms: During the growth of diamond films, in-situ gradient doping of boron atoms is achieved by introducing trimethylboron (B(CH3)3) as a dopant source in a time-sequential manner. By precisely controlling the flux of the dopant source, the boron atom concentration is gradually increased from the side closest to the transition layer (concentration of 1×10⁻⁶). 20 cm -3 ) to the top surface of the film (concentration of 1×10 19 cm -3 The gradient decreases linearly. This gradient distribution creates a built-in potential gradient, which facilitates the directional transport of hot carriers, thereby enhancing thermal conduction.

[0028] Construction and processing of nanoscale pore arrays: After the diamond film is grown, a nanoscale pore array is precisely etched into the film using focused ion beam (FIB) etching technology. In this embodiment, the pores have a hexagonal close-packed structure with a diameter of 15 nm and a pore density of approximately 5 × 10⁻⁶. 11 cm -2 The etching depth extends throughout the entire 30 nm thick diamond film. During etching, the incident angle of the ion beam is precisely controlled so that the axis of the formed channel forms a 22.5° angle with the direction perpendicular to the film surface (i.e., the main heat flux direction). This tilted structure aims to utilize the phonon waveguide effect to guide phonons to propagate in a specific direction, reducing backscattering and increasing net heat flux. After etching, the sample is treated in a hydrogen plasma environment to perform hydrogen termination treatment on the inner wall of the channel. Utilizing the hydrogen atom-saturated carbon dangling bonds, a stable CH bonded surface is formed, effectively passivating the channel surface and significantly reducing the inelastic scattering of phonons on the surface.

[0029] (III) Heat dissipation structure and bonding The heat dissipation structure is made of copper-diamond composite material, which has a thermal conductivity of up to 600 W / (m·K) and a thermal expansion coefficient that is more compatible with semiconductor materials.

[0030] To achieve a low-thermal-resistance, high-strength bond between the high-efficiency thermally conductive layer and the heat dissipation structure, a nanoscale metal bonding layer with a Ti / Pt / Au multilayer structure was first deposited on the top surface of the high-efficiency thermally conductive layer using electron beam evaporation. Finally, the semiconductor chip with the metal bonding layer was soldered to the heat dissipation structure using AuSn eutectic solder, forming a robust mechanical, electrical, and thermal connection with extremely low thermal resistance. Measurements showed that the total interfacial thermal resistance, including the metal bonding layer and the solder layer, was less than 5 × 10⁻⁶. -9 m 2 ·K / W.

[0031] II. Heat dissipation process and effect The heat dissipation process of the semiconductor laser element in this embodiment is as follows: Step S1 (Heat Generation): When the laser element is working, a large amount of heat is generated in the active region.

[0032] Step S2 (Heat Capture): The generated heat is conducted upwards. When the heat reaches the interface between the upper confinement layer and the high-efficiency thermally conductive layer, efficient phonon coupling is achieved due to the presence of the transition layer. Simultaneously, the high-concentration boron doping on the active region side of the high-efficiency thermally conductive layer greatly enhances electron-phonon interactions, allowing the thermal energy to be rapidly absorbed by the electronic system.

[0033] Step S3 (Heat Conduction): The heat entering the high-efficiency thermal conductive layer is efficiently conducted through three mechanisms: phonon heat transfer via the diamond lattice, electron heat transfer introduced by doping, and directional phonon transport via nanopores. The synergistic effect of these three mechanisms results in an effective thermal conductivity of up to 2500 W / (m·K), allowing heat to be rapidly conducted through the layer.

[0034] Step S4 (Heat Dissipation): After passing through the high-efficiency thermally conductive layer and the metal bonding layer, the heat reaches the heat dissipation structure. The copper-diamond composite heat sink, with its high thermal conductivity, rapidly diffuses the concentrated heat laterally and ultimately exchanges heat with the external environment.

[0035] By testing the device prepared in this embodiment and comparing it with a device using a traditional heat dissipation structure, the results show that, under the same power, the active region temperature of the device in this embodiment is significantly reduced, the wavelength temperature drift coefficient is reduced, the slope efficiency is improved, the COD threshold power is increased, and the reliability is also significantly enhanced.

[0036] Example 2 This embodiment provides another specific implementation of the "highly efficient thermally conductive semiconductor laser element" of the present invention. The main difference between this embodiment and Embodiment 1 is that the substrate material, doping strategy and pore structure of the highly efficient thermally conductive layer are different, which aims to demonstrate the flexibility and scalability of the technical solution of the present invention.

[0037] The parts that are the same as in Example 1, such as the materials and fabrication processes of the semiconductor epitaxial structure and heat dissipation structure, can be described in Example 1. The innovation of this example focuses on the design of the high-efficiency thermal conductive layer: Substrate Material: In this embodiment, the high-efficiency thermally conductive layer uses a silicon carbide (SiC) / diamond composite film as the substrate material, forming a "sandwich" structure. Specifically, a 5nm thick 3C-SiC film is first grown on the transition layer, followed by a 20nm thick nanocrystalline diamond film, and finally another 5nm thick 3C-SiC film. The lattice mismatch between 3C-SiC and GaAs is less than that of diamond, which can further reduce interfacial stress, while the middle diamond layer remains the main high thermal conductivity core.

[0038] Doping strategy: This embodiment employs nitrogen (N) and boron (B) co-doping. By simultaneously introducing NH3 and B2H6 gases during the growth process, n-type and p-type compensating doping of the SiC and diamond layers is achieved. This co-doping strategy allows for more flexible control of the material's electrical and thermal properties.

[0039] Nanopore structure: The nano-scale pore array in this embodiment is fabricated using reactive ion etching (RIE) technology. The pores are tapered with a large inlet and a small outlet, and are radially distributed, i.e., arranged radially from the center of the chip to the periphery, to better match the circular heat source distribution of the laser active area. The inner surface of the pores is treated with oxygen plasma to form a Si-O bond or C=O bond passivation layer, which has better stability than CH bonds at high temperatures.

[0040] This embodiment achieves significant heat dissipation by using SiC-based composite materials and optimized channel structures, and its growth process is more compatible with existing semiconductor process lines, potentially leading to lower manufacturing costs.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-efficiency thermally conductive semiconductor laser element, comprising: Substrate; A lower confinement layer, an active region, and an upper confinement layer are sequentially disposed on the substrate; And a heat dissipation structure disposed opposite to the upper limiting layer; The feature is that a high-efficiency thermally conductive layer is disposed between the upper limiting layer and the heat dissipation structure, the high-efficiency thermally conductive layer comprising: a diamond film with high thermal conductivity as a substrate material; and boron atoms doped in the diamond film, wherein the doping concentration of the boron atoms is 1×10⁻⁶. 18 cm -3 Up to 1×10 20 cm -3 ; and a nanoscale pore array formed in the diamond film and extending through its thickness direction, the nanoscale pore array having a pore size of 5 nm to 20 nm and a pore density of 10. 10 cm -2 Up to 10 12 cm -2 .

2. The high-efficiency thermally conductive semiconductor laser element according to claim 1, characterized in that, The thickness of the high-efficiency thermal conductive layer is 10nm to 50nm.

3. The high-efficiency thermally conductive semiconductor laser element according to claim 1, characterized in that, The doping concentration of boron atoms is gradient-distributed along the thickness direction of the high-efficiency thermal conductive layer; The doping concentration of boron atoms gradually decreases from the side closer to the active region to the side closer to the heat dissipation structure. On the side closest to the active region, the boron atom doping concentration is 1 × 10⁻⁶. 20 cm -3 In the middle region of the high-efficiency thermally conductive layer, the doping concentration is 5×10⁻⁶. 19 cm -3 On the side closest to the heat dissipation structure, the doping concentration is 1×10⁻⁶. 19 cm -3 .

4. The high-efficiency thermally conductive semiconductor laser element according to claim 1, characterized in that, The channels in the nanoscale channel array are arranged in a hexagonal close-packed structure, and the axial direction of the channels forms an angle of 15° to 30° with the heat flow direction from the active region to the heat dissipation structure.

5. A high-efficiency thermally conductive semiconductor laser element according to claim 1 or 4, characterized in that, The inner surface of the nanoscale pore array is hydrogen-terminated to form a carbon-hydrogen bonded surface.

6. The high-efficiency thermally conductive semiconductor laser element according to claim 1, characterized in that, A transition layer with a thickness of 2nm to 5nm is provided between the upper confinement layer and the high-efficiency thermal conductive layer. The transition layer is used to alleviate the lattice mismatch between the upper confinement layer and the high-efficiency thermal conductive layer.

7. The high-efficiency thermally conductive semiconductor laser element according to claim 1, characterized in that, A nanoscale metal bonding layer is disposed between the high-efficiency thermally conductive layer and the heat dissipation structure. The metal bonding layer is used to achieve a low thermal resistance electrical and thermal connection between the high-efficiency thermally conductive layer and the heat dissipation structure.

8. The high-efficiency thermally conductive semiconductor laser element according to claim 1, characterized in that, The heat dissipation structure is a copper-based diamond composite heat sink or a microchannel liquid cooling heat sink.

9. A heat dissipation method for a semiconductor laser element, applied to a high-efficiency thermally conductive semiconductor laser element according to any one of claims 1 to 8, characterized in that, The method includes the following steps: S1: Heat generation step, when the semiconductor laser element is working, heat is generated in the active region due to nonradiative recombination of charge carriers and the Joule effect; S2: Heat capture step, wherein the high-efficiency thermally conductive layer efficiently captures heat transferred from the active region via the upper confinement layer through phonon coupling effect, enhanced electron-phonon interaction and reduced interfacial thermal resistance; S3: Heat conduction step, whereby the captured heat is efficiently conducted to the heat dissipation structure through the directional heat conduction path constructed by the nanoscale pore array in the high-efficiency thermal conductive layer, with an equivalent thermal conductivity of up to 2000 W / (m·K) to 3000 W / (m·K); S4: Heat dissipation step, wherein the heat dissipation structure rapidly dissipates the received heat into the surrounding environment.

10. The heat dissipation method for a semiconductor laser element according to claim 9, characterized in that, In the heat generation step, heat generated by nonradiative recombination of charge carriers accounts for 60% to 70% of the total heat, and heat generated by Joule heating accounts for 30% to 40% of the total heat; and / or, in the heat capture step, the interfacial thermal resistance between the high-efficiency thermally conductive layer and the upper confining layer or heat dissipation structure is less than 1 × 10⁻⁶. -8 m 2 ·K / W.

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