Si-doped AlN template, preparation method and AlGaN-based LED light source
By adopting staged growth and Si doping methods on the AlN template, the problems of dislocation density and compressive strain in the AlN template are solved, and high-quality AlGaN-based LED light source epitaxial is achieved, improving device performance.
Patent Information
- Application Number
- CN202510797119.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-08-01
AI Technical Summary
The prior art is difficult to achieve low dislocation density and low pressure strain on the AlN template, resulting in limited improvement in epitaxial quality of AlGaN-based UV LED light sources, especially in long-wavelength ultraviolet LEDs.
Using the method of phased growth and Si doping, amorphous/microcrystalline AlN nucleation layer was deposited on a sapphire substrate, combined with the AlN buffer layer, transition layer and high-quality layer were deposited in the MOCVD reaction chamber, and the Si doping layered variation design was used to reduce the dislocation density and release the compressive strain.
AlN templates with low dislocation density, low pressure strain and high crystallization quality are achieved, which improves the epitaxial quality of deep ultraviolet LEDs and improves the performance of AlGaN-based devices.
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Figure CN120400992A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of epitaxial growth of semiconductor materials, and particularly to an Si-doped AlN template, a preparation method thereof, and an AlGaN-based LED light source. Background Art
[0002] Since the 21st century, significant progress has been made in deep ultraviolet light sources based on group III nitrides. In recent years, light sources in the UVC band (200 - 280 nm) have attracted great attention from researchers due to their high efficiency in inactivating the DNA of bacteria and viruses. Currently, the disinfection function based on UVC light sources has been widely applied in many scenarios: small portable devices, household appliances, food preservation, water treatment, etc., and UVC light sources have been widely used. Compared with traditional UV light sources mainly based on mercury lamps, semiconductor deep ultraviolet light sources based on group III nitride AlGaN materials exhibit many advantages, such as low power consumption, high portability, durability, long working life, strong wavelength modulation ability, and environmental friendliness. Among them, the environmental protection advantage of being mercury-free is particularly prominent.
[0003] As a key substrate material for the epitaxial growth of AlGaN-based UV LEDs, due to the characteristics of epitaxial growth, the dislocation density in the AlN template will extend into the active region to form non-radiative recombination centers. Therefore, obtaining a high-quality AlN template has become an important basis for improving the efficiency of AlGaN-based UV LED light sources. Currently, some scholars have successfully prepared AlN bulk single crystals with a dislocation density lower than 10 5 cm -2 . Although the dislocation density of such single crystals is extremely low, their limited wafer size and high cost severely restrict their application in the large-scale industrial production of DUV LEDs. In view of this, many scholars have focused on the research of AlN heteroepitaxial technology on hetero-substrate Al2O3 with high ultraviolet transparency. However, most of these research methods require a relatively thick AlN epitaxial layer to promote surface merging, dislocation termination, and annihilation. For this reason, researchers have tried to apply high-temperature annealing processes to improve the quality of AlN thin films.
[0004] Although high-temperature annealing can reduce the dislocation density to a certain extent, due to the problem of thermal expansion coefficient mismatch, it will lead to strain deterioration, making the annealed AlN template in a higher compressive strain state. This compressive strain can not only be observed at room temperature, but also exists at the growth temperature of metalorganic chemical vapor deposition (MOVPE). In fact, no matter what preparation method is used, high-quality AlN / sapphire templates after high-temperature treatment usually exhibit a high-pressure strain state.
[0005] In this context, it should be clear that the original intention of improving the quality of AlN template materials is to enhance the performance of subsequent AlGaN-based devices. However, despite numerous efforts in improving the quality of AlN template materials in existing research, the quality of the subsequently grown AlGaN-based devices has not been directly improved, and there are extremely limited reports on achieving higher device performance on such high-quality AlN templates. This is because the coherent strain can still be continued in the AlGaN grown on the AlN template, and for ultraviolet LEDs with longer wavelengths, relaxation problems will also occur.
[0006] In addition, the performance improvement brought about by using high-quality AlN templates is limited to a certain extent, and the improvement in the crystal quality of thick AlGaN epitaxial layers is limited. In fact, the high strain state and low dislocation density in the AlN template pose new challenges to the subsequent AlGaN epitaxial growth. In the process of preparing AlN templates with low dislocation density, how to reduce its compressive strain becomes a key technical problem. Summary of the Invention
[0007] To solve the above technical problems, the present invention provides a Si-doped AlN template, a preparation method thereof, and an AlGaN-based LED light source. The technical solution of the present invention is as follows: In the first aspect, a preparation method of a Si-doped AlN template is provided, which includes: S1, depositing an amorphous / microcrystalline AlN layer on the surface of a sapphire substrate by a magnetron sputtering process as a nucleation layer for subsequent epitaxial growth; S2, pre-treating the nucleation layer in a MOCVD reaction chamber; S3, depositing an AlN buffer layer on the pre-treated nucleation layer in a MOCVD reaction chamber; S4, depositing an AlN transition layer on the AlN buffer layer in a MOCVD reaction chamber; S5, depositing an AlN high-quality layer on the AlN transition layer in a MOCVD reaction chamber; Wherein, the AlN buffer layer is a Si-doped layer with a single concentration, the AlN transition layer is not Si-doped, and the AlN high-quality layer is a composite Si-doped layer with a stratified change in Si doping concentration.
[0008] Optionally, S2 includes: introducing H2 into the MOCVD reaction chamber and baking for 10 - 30 min under the conditions of 1100 - 1300 °C and 50 - 200 mbar.
[0009] Optionally, S5 includes: successively depositing an AlN low-doped layer, an AlN gradient transition layer, an AlN high-doped layer, and an AlN undoped layer on the AlN transition layer in the MOCVD reaction chamber to form an AlN high-quality layer.
[0010] Optionally, S3 includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1150 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min and the flow rate of NH3 to be 0.1 - 20 L / min to deposit an AlN buffer layer, where the Si doping concentration of the AlN buffer layer is 1×10 15 -2×10 19 cm -3 , and the thickness of the AlN buffer layer is 20 - 500 nm; S4 includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1200 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, suspending Si doping, introducing trimethylaluminum and NH3 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min and the flow rate of NH3 to be 0.1 - 20 L / min to deposit an AlN transition layer, and the thickness of the AlN transition layer is 20 - 500 nm.
[0011] Optionally, when depositing the AlN low-doped layer, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN low-doped layer, where the Si doping concentration of the AlN low-doped layer is 1×10 15 -1×10 19 cm -3 , and the thickness of the AlN low-doped layer is 10 - 500 nm; When depositing the AlN gradient transition layer, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN gradient transition layer, where the Si doping concentration of the AlN gradient transition layer gradually changes from the AlN low-doped layer to the AlN high-doped layer, and the thickness of the AlN gradient transition layer is 10 - 500 nm; When depositing the highly doped AlN layer, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2. Trimethylaluminum, NH3, and SiH4 are introduced into the MOCVD reaction chamber. The flow rate of trimethylaluminum is controlled at 10 - 100 μmol / min, and the flow rate of NH3 is controlled at 0.1 - 10 L / min to deposit the highly doped AlN layer. The Si doping concentration of the deposited highly doped AlN layer is at 1×10 16 -2×10 19 cm -3 , and the thickness of the highly doped AlN layer is 100 - 2000 nm; When depositing the undoped AlN layer, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2. Trimethylaluminum and NH3 are introduced into the MOCVD reaction chamber. The flow rate of trimethylaluminum is controlled at 10 - 100 μmol / min, and the flow rate of NH3 is controlled at 0.1 - 10 L / min to deposit the undoped AlN layer. The thickness of the undoped AlN layer is 100 - 500 nm.
[0012] Optionally, when depositing the highly doped AlN layer, SiH4 is introduced in a periodic pulsed manner.
[0013] Optionally, after S5, it further includes: annealing at a temperature of 1300 - 1400 °C in an H2 atmosphere for 10 - 30 min.
[0014] In a second aspect, a Si-doped AlN template is provided, which includes: A nucleation layer deposited on the surface of the sapphire substrate, and the nucleation layer is an amorphous / microcrystalline AlN layer; An AlN buffer layer and an AlN transition layer sequentially deposited on the nucleation layer; An AlN high-quality layer deposited on the AlN transition layer; Wherein, the AlN buffer layer is a Si-doped layer with a single concentration, the AlN transition layer is not Si-doped, and the AlN high-quality layer is a composite Si-doped layer with a stratified change in Si doping concentration.
[0015] Optionally, the AlN high-quality layer includes an AlN low-doped layer, an AlN gradient transition layer, a highly doped AlN layer, and an undoped AlN layer sequentially deposited on the AlN transition layer; The Si doping concentration of the AlN buffer layer is 1×10 15 -2×10 19 cm -3 , and the thickness is 20 - 500 nm; the thickness of the AlN transition layer is 20 - 500 nm; The Si doping concentration of the AlN low-doped layer is 1×10 15 -1×10 19 cm -3 , with a thickness of 10-500 nm; the Si doping concentration of the AlN gradient transition layer gradually changes from the AlN low-doping layer to the AlN high-doping layer, with a thickness of 10-500 nm; the Si doping concentration of the AlN high-doping layer is 1×10 16 -2×10 19 cm -3 , with a thickness of 100-2000 nm; and the thickness of the AlN undoped layer is 100-500 nm.
[0016] In a third aspect, an AlGaN-based LED light source is provided, which adopts the Si-doped AlN template described in the second aspect.
[0017] All the above optional technical solutions can be combined arbitrarily, and the present invention does not provide detailed descriptions of the structures after each combination.
[0018] By means of the above solution, the beneficial effects of the present invention are as follows: By providing an AlN buffer layer, an AlN transition layer and an AlN high-quality layer, and setting the AlN buffer layer as a Si-doped layer with a single concentration, the AlN transition layer is not Si-doped, and the AlN high-quality layer is a composite Si-doped layer with layered Si-doping concentration changes, a Si-doped AlN template structure with staged growth and Si-doping layered design and a preparation method thereof are provided. The Si-doped AlN template with staged growth and Si-doping layered design can be made to have a good appearance and morphology, maintain low dislocation density, low compressive strain, surface smoothness and high crystal quality, thereby improving the epitaxial quality of deep ultraviolet LEDs.
[0019] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 Schematic diagram of the structure of a Si-doped AlN template provided in one embodiment of the present invention.
[0021] Figure 2 Schematic diagram of the structure of a Si-doped AlN template provided in another embodiment of the present invention.
[0022] Figure 3 This is a schematic structural diagram of the AlN template provided in Comparative Example 1.
[0023] Figure 4It is a schematic structural diagram of the AlN template provided in Comparative Example 2.
[0024] Figure 5 It is a schematic diagram of the comparison result of (102) FWHM obtained by the X-ray diffractometer for the examples and comparative examples.
[0025] Figure 6 It is a schematic diagram of the comparison result of the AFM images of the examples and comparative examples by the atomic force microscope.
[0026] Figure 7 It is a schematic diagram of the test result of the surface roughness of the examples and comparative examples by the atomic force microscope. Detailed implementation manners
[0027] The following combines the accompanying drawings and examples to further describe in detail the specific implementation manners of the present invention. The following examples are used to illustrate the present invention, but do not limit the scope of the present invention.
[0028] To solve the technical problem of reducing the compressive strain in the preparation process of the AlN template with a low dislocation density, the embodiments of the present invention utilize Si-doped AlN to achieve this. Specifically, since the atomic radius of Si is slightly larger than that of Al, during the process of Si doping into AlN, Si atoms will replace Al atoms and enter the lattice, thereby causing local lattice distortion. Si doping may also change the electron distribution in the AlN layer, affect the core structure and energy of dislocations, reduce the energy barrier of dislocation tilt, thereby affecting the movement and interaction of dislocations in the AlN template, making dislocations more likely to tilt, changing the dislocation concentration and distribution, providing a more effective mechanism for strain relaxation, effectively reducing the compressive strain, and further reducing the full width at half maximum and improving the crystal quality.
[0029] Based on the above content, the preparation method of the Si-doped AlN template provided by the embodiments of the present invention includes the following steps S1 to S5: S1, a magnetron sputtering process is used to deposit an amorphous / crystalline AlN layer on the surface of the sapphire substrate 101 as the nucleation layer 102 for subsequent epitaxial growth.
[0030] In the specific implementation of this step, the sputtering power can be controlled at 200 - 4000 W, the Ar gas flow rate at 20 - 50 sccm, the N2 flow rate at 100 - 300 sccm, the O2 flow rate at 0 - 5 sccm, and the temperature at 500 - 700 °C. The thickness of the nucleation layer 102 is 1 - 50 nm. And, after sputtering the nucleation layer 102 on the sapphire substrate 101, it is placed in a MOCVD device for subsequent processes.
[0031] S2, pre-treat the nucleation layer 102 in the MOCVD reaction chamber.
[0032] In a specific embodiment, S2 includes: introducing H2 into the MOCVD reaction chamber and baking it for 10 - 30 min under the environment of 1100 - 1300 °C and 50 - 200 mbar; this step is used to remove impurities on the surface of the nucleation layer 102.
[0033] S3, depositing an AlN buffer layer 103 on the pretreated nucleation layer 102 in the MOCVD reaction chamber.
[0034] In specific implementation, S3 includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1150 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min and the flow rate of NH3 to be 0.1 - 20 L / min to deposit the AlN buffer layer 103, and the Si doping concentration of the AlN buffer layer 103 is 1×10 15 -2×10 19 cm -3 , and the thickness of the AlN buffer layer 103 is 20 - 500 nm.
[0035] S4, depositing an AlN transition layer 104 on the AlN buffer layer 103 in the MOCVD reaction chamber.
[0036] In specific implementation, S4 includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1200 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, suspending Si doping, introducing trimethylaluminum and NH3 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min and the flow rate of NH3 to be 0.1 - 20 L / min to deposit the AlN transition layer 104, and the thickness of the AlN transition layer 104 is 20 - 500 nm. Among them, the AlN transition layer 104 is used to repair surface defects of the AlN buffer layer 103 and promote two-dimensional growth of the subsequent high-quality AlN layer 105.
[0037] S5, depositing a high-quality AlN layer 105 on the AlN transition layer 104 in the MOCVD reaction chamber.
[0038] It should be noted that in the embodiment of the present invention, the AlN buffer layer 103 is a Si-doped layer with a single concentration, the AlN transition layer 104 is not Si-doped, and the high-quality AlN layer 105 is a composite Si-doped layer with a stratified change in Si doping concentration. Regarding how the Si doping concentration in the high-quality AlN layer 105 changes, the embodiment of the present invention does not make specific limitations. For example, from high to low to non-doping, etc.
[0039] In a specific embodiment, S5 includes: sequentially depositing an AlN low-doped layer 105-1, an AlN gradient transition layer 105-2, an AlN high-doped layer 105-3, and an AlN undoped layer 105-4 on the AlN transition layer 104 in an MOCVD reaction chamber to form an AlN high-quality layer 105. The AlN high-quality layer 105 of this structure is a Si-doped "sandwich" structure. Among them, the AlN low-doped layer 105-1 is used to suppress interface dislocations, the AlN gradient transition layer 105-2 is used for gradual strain relaxation, the AlN high-doped layer 105-3 is used to terminate threading dislocations, and the AlN undoped layer 105-4 is used to improve the surface morphology.
[0040] During specific implementation, when depositing the AlN low-doped layer 105-1, the Si doping is restored, including: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min, and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN low-doped layer 105-1. The Si doping concentration of the AlN low-doped layer 105-1 is 1×10 15 -1×10 19 cm -3 , and the thickness of the AlN low-doped layer 105-1 is 10 - 500 nm; When depositing the AlN gradient transition layer 105-2, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min, and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN gradient transition layer 105-2. The Si doping concentration of the AlN gradient transition layer 105-2 gradually changes from the AlN low-doped layer 105-1 to the AlN high-doped layer 105-3, and the thickness of the AlN gradient transition layer 105-2 is 10 - 500 nm; When depositing the AlN high-doped layer 105-3, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min, and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN high-doped layer 105-3. The Si doping concentration for depositing the AlN high-doped layer 105-3 is 1×10 16 -2×10 19 cm -3, the thickness of the highly doped AlN layer 105-3 is 100-2000 nm; When depositing the undoped AlN layer 105-4, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050-1300 °C, the pressure to be 10-100 mbar, the carrier gas to be H2 (10-50 L / min), introducing trimethylaluminum and NH3 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10-100 μmol / min, and the flow rate of NH3 to be 0.1-10 L / min to deposit the undoped AlN layer 105-4, and the thickness of the undoped AlN layer 105-4 is 100-500 nm.
[0041] The structure of the Si-doped AlN template prepared by the above preparation method is as Figure 1 and Figure 2 shown.
[0042] In a specific embodiment, when depositing the highly doped AlN layer 105-3, the method of periodically pulsed introduction of SiH4 can be adopted instead of single-component doping after continuous gradient transition. Specifically, the method of periodically pulsed introduction of SiH4 can achieve a local concentration gradient by adjusting the pulse frequency and duty cycle. For example: the pulse period is to switch the SiH4 flow rate every time 1-50 nm is grown, realizing the high→low→high cycle of the SiH4 flow rate. Pulse doping can generate a micro-area strain gradient, promote dislocation tilt and annihilation, further release the residual compressive strain, and thus can avoid the accumulation of interface defects caused by the gradual change of concentration in continuous gradient doping and improve the surface smoothness.
[0043] In a specific embodiment, after the S5, an annealing process can also be included. The annealing process can specifically be: annealing for 10-30 min in an H2 atmosphere at a temperature of 1300-1400 °C. Through the annealing process, the interfacial micro-strain can be eliminated, and dislocation slip and rearrangement can be promoted; the dislocation density of the AlN template can be further reduced after annealing, and the point defects inside the AlN template can be repaired.
[0044] The embodiment of the present invention also provides a Si-doped AlN template, which can be prepared by using the preparation method of the Si-doped AlN template described in the above embodiment, including: a nucleation layer 102 deposited on the surface of the sapphire substrate 101, and the nucleation layer 102 is an amorphous / microcrystalline AlN layer; an AlN buffer layer 103 and an AlN transition layer 104 sequentially deposited on the nucleation layer 102; an AlN high-quality layer 105 deposited on the AlN transition layer 104; wherein, the AlN buffer layer is a Si-doped layer with a single concentration, the AlN transition layer is not doped with Si, and the AlN high-quality layer is a composite Si-doped layer with a stratified change in Si doping concentration.
[0045] In a specific embodiment, the high-quality AlN layer 105 includes an AlN low-doped layer 105-1, an AlN gradient transition layer 105-2, an AlN high-doped layer 105-3, and an AlN undoped layer 105-4 sequentially deposited on the AlN transition layer 104; The Si doping concentration of the AlN buffer layer 103 is 1×10 15 -2×10 19 cm -3 , and the thickness is 20 - 500 nm; the thickness of the AlN transition layer 104 is 20 - 500 nm; the Si doping concentration of the AlN low-doped layer 105-1 is 1×10 15 -1×10 19 cm -3 , and the thickness is 10 - 500 nm; the Si doping concentration of the AlN gradient transition layer 105-2 gradually changes from the AlN low-doped layer 105-1 to the AlN high-doped layer 105-3, and the thickness is 10 - 500 nm; the Si doping concentration of the AlN high-doped layer 105-3 is 1×10 16 -2×10 19 cm -3 , and the thickness is 100 - 2000 nm; the thickness of the AlN undoped layer 105-4 is 100 - 500 nm.
[0046] To verify the performance of the Si-doped AlN template prepared by the preparation method provided in the embodiments of the present invention and the Si-doped AlN template with the above structure, the following Comparative Example 1, Comparative Example 2, and Example are provided. Specifically, the AlN template provided in the Example is the Si-doped AlN template described in the above Example, the AlN template provided in Comparative Example 1 is not doped with Si, and its structure is as Figure 3 shown, including a first nucleation layer 202 and an AlN layer 203 sequentially deposited on a first substrate 201; the AlN template provided in Comparative Example 2 is a Si-doped AlN layer with a single Si doping concentration, and its structure is as Figure 4 shown, including a second nucleation layer 302 and a Si-doped AlN layer 303 sequentially deposited on a second substrate 301, and the Si doping concentration is 1×10[[ID=?]] 15 -2×10 19 cm -3 .
[0047] The (102) FWHM comparison results are obtained by an X-ray diffractometer, as shown in Figure 5 , and from Figure 5 It should be noted that there seems to be an incomplete or incorrect tag in the original text around line 28 which might affect the accurate translation. The translated text is provided as accurately as possible based on the available content.It can be obtained that the FWHM of the AlN template (102) in Comparative Example 1 is 281 arcsec, the FWHM of the AlN template (102) in Comparative Example 2 is 242 arcsec, and the FWHM of the AlN template (102) in the Example is 237 arcsec, which indicates that the crystal quality of the AlN template is slightly improved after doping with Si. Subsequently, AlGaN (with a thickness of 2 - 2.5 μm) was grown on the AlN templates of the comparative examples and the example in MOCVD under the same conditions, and the (102) FWHM of AlGaN was tested ( Figure 5 ), and it can be obtained that the FWHM of the AlN template (102) in Comparative Example 1 is 535 arcsec, the FWHM of the AlN template (102) in Comparative Example 2 is 331 arcsec, and the FWHM of the AlN template (102) in the Example is 304 arcsec, indicating that the AlN template doped with Si can improve the crystal quality of the subsequently grown AlGaN.
[0048] The AFM image was obtained by an atomic force microscope, and the comparison results are shown in Figure 6 , and from Figure 6 it can be obtained that Comparative Example 1 and the Example have similar morphologies, and there are many hexagonal protrusions on the surface of Comparative Example 2.
[0049] The atomic force microscope was used to test the surface roughness (Rq), and the comparison results are as shown in Figure 7 , and from Figure 7 it can be obtained that the surface roughness of the AlN template in Comparative Example 1 is 2.10 nm, the surface roughness of Comparative Example 2 is 6.25 nm, and the surface roughness of the Example is 2.75 nm. It can be seen from this that the surface roughness of the Si-doped AlN template without hierarchical gradient doping is very large, and for the AlN template with hierarchical gradient doping, its appearance and surface roughness are similar to those of the AlN template without Si doping.
[0050] This conclusion can be confirmed by the results observed through an optical microscope: the AlN templates of Comparative Example 1 and the Example can observe a stepped morphology under the microscope, and have similar appearance morphologies at 200X and 500X; the morphology of the AlN template in Comparative Example 2 is rougher under the microscope, and many granular substances can be clearly observed at 500X, corresponding to the hexagonal protrusions observed in the AFM.
[0051] The Si-doped AlN template and its preparation method provided by the embodiment of the present invention have the following characteristics: (1) Hierarchical doping strategy: Si doping and hierarchical design can obtain a good appearance morphology; doping Si in the AlN buffer layer 103 can induce dislocation tilt to release strain; performing Si doping design can maintain a low dislocation density, low pressure strain and surface smoothness.
[0052] (2) Transition layer design: The undoped AlN transition layer 104 can repair interface defects and avoid deterioration of the surface morphology during subsequent growth caused by excessive Si.
[0053] (3) Process co-optimization: By combining sputtering and MOCVD techniques, an AlN template with a low dislocation density and high crystal quality can be achieved, which can improve the quality of the subsequently grown AlGaN.
[0054] In summary, the embodiments of the present invention provide a staged-growth, Si-doped AlN template structure and its preparation method, which can achieve an AlN template with a low dislocation density, low compressive strain, high crystal quality, and good surface morphology, thereby being able to improve the epitaxial quality of deep ultraviolet LEDs.
[0055] The embodiments of the present invention also provide an AlGaN-based LED light source, which includes the above-mentioned Si-doped AlN template. By providing that the AlGaN-based LED light source includes the above-mentioned Si-doped AlN template, the epitaxial quality of deep ultraviolet LEDs can be improved.
[0056] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.
Claims
1. A method for preparing an Si-doped AlN template, characterized in that Comprising: S1, depositing an amorphous / microcrystalline AlN layer on the surface of a sapphire substrate by magnetron sputtering process as a nucleation layer for subsequent epitaxial growth; S2, pre-treating the nucleation layer in a MOCVD reaction chamber; S3, depositing an AlN buffer layer on the pre-treated nucleation layer in a MOCVD reaction chamber; S4, depositing an AlN transition layer on the AlN buffer layer in a MOCVD reaction chamber; S5, depositing an AlN high-quality layer on the AlN transition layer in a MOCVD reaction chamber; Wherein, the AlN buffer layer is a Si-doped layer with a single concentration, the AlN transition layer is not Si-doped, and the AlN high-quality layer is a composite Si-doped layer with a graded Si doping concentration.
2. The method for preparing the Si-doped AlN template according to claim 1, wherein, The S2 includes: introducing H2 into the MOCVD reaction chamber and baking for 10 - 30 min under the environment of 1100 - 1300 °C and 50 - 200 mbar.
3. The preparation method of the Si-doped AlN template according to claim 1, wherein, The S5 includes: Sequentially depositing an AlN low-doped layer, an AlN gradient transition layer, an AlN high-doped layer, and an AlN undoped layer on the AlN transition layer in a MOCVD reaction chamber to form an AlN high-quality layer.
4. The method for preparing an Si-doped AlN template according to claim 1 or 2 or 3, characterized in that, The S3 includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1150 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min and the flow rate of NH3 to be 0.1 - 20 L / min to deposit an AlN buffer layer, the Si doping concentration of the AlN buffer layer being 1×10 15 -2×10 19 cm -3 , and the thickness of the AlN buffer layer being 20 - 500 nm; The S4 includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1200 °C, the pressure to be 10 - 100 mbar, the carrier gas to be H2, suspending Si doping, introducing trimethylaluminum and NH3 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min, and the flow rate of NH3 to be 0.1 - 2 L / min to deposit the AlN transition layer, and the thickness of the AlN transition layer is 20 - 500 nm.
5. The method for preparing a Si-doped AlN template according to claim 3, wherein When depositing the AlN low-doped layer, it includes: controlling the temperature of the MOCVD reaction chamber at 1050 - 1300 °C, the pressure at 10 - 100 mbar, and the carrier gas as H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum at 10 - 100 μmol / min and the flow rate of NH3 at 0.1 - 10 L / min to deposit the AlN low-doped layer, the Si doping concentration of the AlN low-doped layer is 1×10 15 -1×10 19 cm -3 , and the thickness of the AlN low-doped layer is 10 - 500 nm; When depositing the AlN gradient transition layer, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min, and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN gradient transition layer, the Si doping concentration of the AlN gradient transition layer gradually changes from the AlN low-doped layer to the AlN high-doped layer, and the thickness of the AlN gradient transition layer is 10 - 500 nm; When depositing the AlN highly doped layer, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, and the carrier gas to be H2, introducing trimethylaluminum, NH3, and SiH4 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min, and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN highly doped layer, and the Si doping concentration of the deposited AlN highly doped layer is 1×10 16 -2×10 19 cm -3 , and the thickness of the AlN highly doped layer is 100 - 2000 nm; When depositing the AlN undoped layer, it includes: controlling the temperature of the MOCVD reaction chamber to be 1050 - 1300 °C, the pressure to be 10 - 100 mbar, the carrier gas to be H2, introducing trimethylaluminum and NH3 into the MOCVD reaction chamber, controlling the flow rate of trimethylaluminum to be 10 - 100 μmol / min, and the flow rate of NH3 to be 0.1 - 10 L / min to deposit the AlN undoped layer, and the thickness of the AlN undoped layer is 100 - 500 nm.
6. The method for preparing the Si-doped AlN template according to claim 5, wherein When depositing the AlN high-doped layer, SiH4 is introduced in a periodic pulsed manner.
7. The preparation method of the Si-doped AlN template according to claim 1, characterized in that, After the S5, it further includes: Annealing for 10 - 30 min in an H2 atmosphere at a temperature of 1300 - 1400 °C.
8. A Si-doped AlN template, characterized in that, Comprising: A nucleation layer deposited on the surface of a sapphire substrate, the nucleation layer being an amorphous / microcrystalline AlN layer; An AlN buffer layer and an AlN transition layer sequentially deposited on the nucleation layer; An AlN high-quality layer deposited on the AlN transition layer; Wherein, the AlN buffer layer is a Si-doped layer with a single concentration, the AlN transition layer is not Si-doped, and the AlN high-quality layer is a composite Si-doped layer with a stratified change in Si doping concentration.
9. The Si-doped AlN template according to claim 8, wherein The AlN high-quality layer includes an AlN low-doped layer, an AlN gradient transition layer, an AlN high-doped layer, and an AlN undoped layer sequentially deposited on the AlN transition layer; The Si doping concentration of the AlN buffer layer is 1×10 15 -2×10 19 cm -3 , with a thickness of 20 - 500 nm; the thickness of the AlN transition layer is 20 - 500 nm; The Si doping concentration of the AlN low-doped layer is 1×10 15 -1×10 19 cm -3 , and the thickness is 10 - 500 nm; the Si doping concentration of the AlN gradient transition layer gradually changes from the AlN low-doped layer to the AlN high-doped layer, and the thickness is 10 - 500 nm; the Si doping concentration of the AlN high-doped layer is 1×10 16 -2×10 19 cm -3 , and the thickness is 100 - 2000 nm; the thickness of the undoped AlN layer is 100 - 500 nm.
10. An AlGaN-based LED light source, characterized in that, Use the Si-doped AlN template according to claim 8 or 9.