An ultraviolet absorption enhanced semiconductor thin film, a preparation method thereof and an application thereof

Abstract

The present invention provides an ultraviolet absorption enhanced semiconductor thin film, a preparation method and an application thereof. The ultraviolet absorption enhanced semiconductor thin film comprises a substrate, and an aluminum intermediate layer and an aluminum nitride dielectric layer which are sequentially stacked on one surface of the substrate. The ultraviolet absorption enhanced semiconductor thin film of the present invention can utilize the combined action of interface phase shift and absorption phase shift to make the reflection on the upper surface of the ultraviolet absorption enhanced semiconductor thin film with a thickness of several nanometers tend to zero, thereby increasing the light absorption of the semiconductor layer. While ensuring that the thickness of the ultraviolet absorption enhanced semiconductor thin film is small, the light absorption intensity is enhanced, thereby improving the response speed of the photodetector.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor materials, and relates to an ultraviolet absorption enhanced semiconductor thin film, a preparation method thereof, and an application thereof. Background Art

[0002] Ultraviolet detectors are widely used in the fields of ultraviolet radiation measurement, ozone monitoring, air pollution monitoring, space communication, aircraft guidance, blood analysis, mercury lamp disinfection monitoring, etc. An ideal semiconductor detector needs to have the following characteristics: high sensitivity, high responsivity, high signal-to-noise ratio, high spectral selectivity, high speed, and high stability.

[0003] Aluminum nitride (AlN) material has the characteristics of high temperature resistance, good chemical stability, and large bandgap. Its bandgap width is 6.2 eV, corresponding to an absorption wavelength of 200 nm, and it is an excellent candidate material for deep ultraviolet detectors in the vacuum band. The AlN vacuum photodetector based on the Schottky junction has the advantages of small volume, fast response speed, low energy consumption, and natural cut-off band edge, which is of great significance for coping with space weather and monitoring the occurrence and changes of solar storms and other space disasters, and contributes to the development of solar-terrestrial physics and geospace science, and has broad application prospects.

[0004] CN119050173A discloses an aluminum nitride vacuum detector, including: a sapphire substrate; an aluminum nitride buffer layer, an aluminum nitride epitaxial layer, and an n-type aluminum gallium nitride layer stacked in sequence on the sapphire substrate along a first direction; an aluminum nitride layer, a silicon dioxide insulating film, and a first metal contact layer, which are arranged side by side along a second direction on the side of the n-type aluminum gallium nitride layer away from the sapphire substrate, wherein the second direction is perpendicular to the first direction; a metal platinum transparent electrode, which is arranged on the side of the aluminum nitride layer away from the sapphire substrate; and a second metal contact layer, which is arranged on the side of the metal platinum transparent electrode away from the sapphire substrate.

[0005] CN118507579A discloses a Schottky structure-based aluminum nitride vacuum detector, which includes, from bottom to top: a substrate, an AlN buffer layer, an AlN epitaxial layer, an n-AlGaN layer, an AlN layer, and a transparent electrode layer; one side of the AlN layer and the transparent electrode layer exposes the mesa of the n-AlGaN layer, and a first metal electrode is arranged on the mesa, and the first metal electrode forms an ohmic contact with the n-AlGaN layer; an insulating film is arranged on the side of the AlN layer and the transparent electrode layer where the mesa is exposed, and a second metal electrode is arranged on the transparent electrode layer to form a Schottky structure.

[0006] The defects of the photosensitive layer of the detector described in the above solution are also increased due to the larger thickness, resulting in a longer carrier migration time, thereby limiting the response speed of the detector. Summary of the Invention

[0007] The object of the present invention is to provide an ultraviolet absorption enhanced semiconductor thin film, a preparation method and an application thereof. The ultraviolet absorption enhanced semiconductor thin film of the present invention can utilize the combined action of interface phase shift and absorption phase shift to make the reflection on the upper surface of the ultraviolet absorption enhanced semiconductor thin film with a thickness of several nanometers tend to zero, thereby increasing the light absorption of the semiconductor layer. While ensuring that the thickness of the ultraviolet absorption enhanced semiconductor thin film is small, the light absorption intensity is enhanced, thereby improving the response speed of the photodetector.

[0008] To achieve the object of the present invention, the following technical solutions are adopted:

[0009] In the first aspect, the present invention provides an ultraviolet absorption enhanced semiconductor thin film, which includes a substrate and an aluminum intermediate layer and an aluminum nitride dielectric layer sequentially stacked on one side surface of the substrate.

[0010] The ultraviolet absorption enhanced semiconductor thin film of the present invention is an 1 I 1 M sub structure, where 1 I 1 represents the upper high-absorption dielectric layer semiconductor thin film, i.e., the aluminum nitride dielectric layer, and sub M

[0011] preferably, the thickness of the aluminum nitride dielectric layer is 3 nm to 10 nm, such as: 3 nm, 5 nm, 8 nm, 9 nm or 10 nm, etc., not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0012] preferably, the substrate includes a sapphire substrate.

[0013] Preferably, the thickness of the substrate is 400 μm to 500 μm, such as: 400 μm, 420 μm, 450 μm, 480 μm or 500 μm, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0014] Preferably, the thickness of the aluminum intermediate layer is 100 nm to 150 nm, such as: 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0015] In a second aspect, the present invention provides a method for preparing the ultraviolet absorption enhanced semiconductor thin film as described in the first aspect. The preparation method includes the following steps:

[0016] (1) Depositing a first aluminum source on the substrate by molecular beam epitaxy to form an aluminum intermediate layer, obtaining a semi-finished thin film;

[0017] (2) Transferring the semi-finished thin film to a plasma enhanced atomic layer deposition system, introducing a second aluminum source into the plasma enhanced atomic layer deposition system through a carrier gas, introducing plasma nitrogen into the plasma enhanced atomic layer deposition system. The plasma nitrogen reacts with the second aluminum source chemically adsorbed on the surface of the aluminum intermediate layer of the semi-finished thin film to deposit aluminum nitride on the aluminum intermediate layer of the semi-finished thin film, forming an aluminum nitride dielectric layer, obtaining the ultraviolet absorption enhanced semiconductor thin film.

[0018] The vacuum interconnection system of the present invention connects the molecular beam epitaxy deposition equipment and the plasma enhanced atomic layer deposition system by using an ultra-high vacuum pipeline, solving the pollution problems such as dust, surface oxidation and adsorption that are difficult to solve in the traditional cleanroom mode.

[0019] Preferably, the first aluminum source in step (1) includes high-purity aluminum, and the purity of the high-purity aluminum in the present invention is ≥99.9999%.

[0020] Preferably, the substrate is cooled before the molecular beam epitaxy in step (1).

[0021] Preferably, after the cooling treatment, the temperature of the substrate is 25 °C to 80 °C, such as: 25 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C or 80 °C, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0022] Preferably, the deposition rate of the molecular beam epitaxy in step (1) is 0.5 nm / s to 1.5 nm / s, for example: 0.5 nm / s, 0.8 nm / s, 1 nm / s, 1.2 nm / s, or 1.5 nm / s, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0023] Preferably, the time of the molecular beam epitaxy in step (1) is 1 min to 3 min, for example: 1 min, 1.2 min, 1.5 min, 1.8 min, 2 min, 2.5 min, or 3 min, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0024] Preferably, during the molecular beam epitaxy in step (1), the surface of the substrate to be evaporated is inverted and parallel to the evaporation source, and rotates at a speed of 4 revolutions per minute to 6 revolutions per minute, for example: 4 revolutions per minute, 4.5 revolutions per minute, 5 revolutions per minute, 5.5 revolutions per minute, or 6 revolutions per minute, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0025] In the present invention, the surface of the substrate to be evaporated is inverted and parallel to the evaporation source, that is, the substrate is located above the evaporation source, the surface to be evaporated is inverted, parallel, and facing the evaporation source for hollow evaporation.

[0026] Preferably, after forming the aluminum intermediate layer in step (1), the semi-finished thin film is transferred to a plasma-enhanced atomic layer deposition system through vacuum interconnection for depositing aluminum nitride.

[0027] In the present invention, nanomaterials are directly prepared in an ultra-high vacuum environment (similar to the lunar environment) through vacuum interconnection to keep the intrinsic properties of the materials free from external contamination. The present invention uses ultra-high vacuum pipelines to connect various functional devices to solve the pollution problems of dust, surface oxidation, and adsorption that are difficult to solve in the traditional cleanroom mode (mainly to solve the problems of surface oxidation and surface impurities causing increased roughness).

[0028] Preferably, before introducing the second aluminum source into the plasma-enhanced atomic layer deposition system in step (2), the semi-finished thin film is heat-treated.

[0029] Preferably, after the heat treatment, the temperature of the semi-finished thin film is 300 °C to 350 °C, for example: 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, or 350 °C, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0030] Preferably, the second aluminum source in step (2) includes trimethylaluminum.

[0031] Preferably, the carrier gas for the plasma-enhanced atomic layer deposition in step (2) includes argon.

[0032] Preferably, the flow rate of the argon is 15 sccm to 20 sccm, such as: 15 sccm, 16 sccm, 17 sccm, 18 sccm, 19 sccm, or 20 sccm, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0033] Preferably, the flow rate of the plasma nitrogen in step (2) is 2 sccm to 8 sccm, such as: 2 sccm, 3 sccm, 4 sccm, 5 sccm, 6 sccm, 7 sccm, or 8 sccm, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0034] Preferably, while introducing the plasma nitrogen into the plasma-enhanced atomic layer deposition system in step (2), argon plasma and hydrogen plasma are also introduced.

[0035] Preferably, the flow rate of the argon plasma is 3 sccm to 5 sccm, such as: 3 sccm, 3.5 sccm, 4 sccm, 4.5 sccm, or 5 sccm, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0036] Preferably, the flow rate of the hydrogen plasma is 15 sccm to 25 sccm, such as: 15 sccm, 18 sccm, 20 sccm, 22 sccm, or 25 sccm, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0037] Preferably, the power of the plasma-enhanced atomic layer deposition in step (2) is 250 W to 350 W, such as: 250 W, 280 W, 300 W, 320 W, or 350 W, etc. It is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0038] In a third aspect, the present invention provides a photodetector, and the photodetector includes the ultraviolet absorption-enhanced semiconductor thin film as described in the first aspect.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The ultraviolet absorption-enhanced semiconductor thin film of the present invention can utilize the combined action of interface phase shift and absorption phase shift to make the reflection on the upper surface of the ultraviolet absorption-enhanced semiconductor thin film with a thickness of several nanometers tend to zero, thereby increasing the light absorption of the semiconductor layer. While ensuring that the thickness of the ultraviolet absorption-enhanced semiconductor thin film is small, the light absorption intensity is enhanced, thereby improving the response speed of the photodetector.

[0041] (2) The structure of the ultraviolet absorption-enhanced semiconductor thin film of the present invention also has good stability and reliability. Due to the high thermal conductivity and good chemical stability of the AlN material itself, this structure can maintain stable performance under harsh environmental conditions. This is very important for ultraviolet photodetectors in practical applications because they need to work reliably in various extreme environments.

[0042] (3) The structure of the ultraviolet absorption-enhanced semiconductor thin film of the present invention is simple, and the preparation process is easy to implement. While reducing costs, it takes into account good selective absorption effects, avoiding problems such as the large processing difficulty and low error tolerance rate of complex film systems.

[0043] (4) The maximum light absorption rate of the ultraviolet absorption-enhanced semiconductor thin film of the present invention can reach more than 49.5%. By adjusting the thickness of the aluminum nitride layer, the maximum light absorption rate of the ultraviolet absorption-enhanced semiconductor thin film can reach 90%. DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic structural diagram of the ultraviolet absorption-enhanced semiconductor thin film provided by an embodiment of the present invention. 1 is a sapphire substrate, 2 is an aluminum intermediate layer, 3 is an aluminum nitride dielectric layer, and I, II, and III are parallel reflected lights generated when the absorption phase shift and the interface phase shift of the aluminum nitride dielectric layer are superimposed.

[0045] Figure 2 is a comparative curve graph of the reflection of the ultraviolet absorption-enhanced semiconductor thin films prepared in Example 1 and Examples 3-7.

[0046] Figure 3 is a comparative graph of the light absorption curves of the ultraviolet absorption-enhanced semiconductor thin films prepared in Example 2 and Comparative Examples 1-3.

[0047] Figure 4 is a comparative graph of the light absorption curves of the ultraviolet absorption-enhanced semiconductor thin films prepared in Example 3 and Comparative Examples 4-6. DETAILED DESCRIPTION OF THE INVENTION

[0048] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0049] The purity of the high-purity aluminum used in the examples and comparative examples of the present invention is 99.99999%.

[0050] Example 1

[0051] This example provides an ultraviolet absorption-enhanced semiconductor thin film. The structural schematic diagram of the ultraviolet absorption-enhanced semiconductor thin film is as shown in Figure 1 the figure. The ultraviolet absorption-enhanced semiconductor thin film includes a sapphire substrate 1 with a thickness of 450 μm, an aluminum intermediate layer 2 with a thickness of 120 nm, and an aluminum nitride dielectric layer 3 with a thickness of 4 nm, which are sequentially stacked on the surface of the sapphire substrate 1. The ultraviolet absorption-enhanced semiconductor thin film is prepared by the following method:

[0052] (1) Using a substrate refrigeration system, the temperature of the sapphire substrate with a thickness of 450 μm is controlled at 60°C. By using molecular beam epitaxy, the sapphire substrate is inverted and perpendicular to the aluminum source, and it rotates at a self-rotation speed of 5 revolutions per minute. The high-purity aluminum is controlled to deposit at a speed of 1 nm / s for 2 minutes to form an aluminum intermediate layer with a thickness of 120 nm, obtaining a semi-finished thin film;

[0053] (2) Through a vacuum interconnection system, the semi-finished thin film is transferred to a plasma-enhanced atomic layer deposition system. The semi-finished thin film is heated to 300°C. Trimethylaluminum is introduced into the plasma-enhanced atomic layer deposition system using argon with a flow rate of 18 sccm as the carrier gas. Plasma nitrogen, plasma argon, and plasma hydrogen are generated from nitrogen, argon, and hydrogen. Plasma nitrogen, plasma argon, and plasma hydrogen are respectively introduced into the plasma-enhanced atomic layer deposition system at flow rates of 5 sccm, 4 sccm, and 20 sccm. At a power of 300 W, the reaction is carried out for 25 minutes to form an aluminum nitride dielectric layer with a thickness of 4 nm, obtaining the ultraviolet absorption-enhanced semiconductor thin film.

[0054] Example 2

[0055] This example provides an ultraviolet absorption-enhanced semiconductor thin film. The structural schematic diagram of the ultraviolet absorption-enhanced semiconductor thin film is as shown in Figure 1 the figure. The ultraviolet absorption-enhanced semiconductor thin film includes a sapphire substrate 1 with a thickness of 400 μm, an aluminum intermediate layer 2 with a thickness of 150 nm, and an aluminum nitride dielectric layer 3 with a thickness of 3 nm, which are sequentially stacked on the surface of the sapphire substrate 1. The ultraviolet absorption-enhanced semiconductor thin film is prepared by the following method:

[0056] (1) Use a substrate cooling system to control the temperature of a sapphire substrate with a thickness of 400 μm at 50 °C. Adopt molecular beam epitaxy. The sapphire substrate is inverted and perpendicular to the aluminum source, and rotates at a rotation speed of 4 revolutions per minute. Control high-purity aluminum to deposit at a speed of 0.5 nm / s for 5 minutes to form an aluminum intermediate layer with a thickness of 150 nm, obtaining a semi-finished film;

[0057] (2) Through a vacuum interconnection system, transfer the semi-finished film to a plasma-enhanced atomic layer deposition system. Heat the semi-finished film to 320 °C. Use argon with a flow rate of 20 sccm as the carrier gas to introduce trimethylaluminum into the plasma-enhanced atomic layer deposition system. Generate plasma nitrogen, plasma argon, and plasma hydrogen from nitrogen, argon, and hydrogen. Introduce plasma nitrogen, plasma argon, and plasma hydrogen into the plasma-enhanced atomic layer deposition system at flow rates of 8 sccm, 5 sccm, and 25 sccm respectively. React for 20 minutes at a power of 350 W to form a aluminum nitride dielectric layer with a thickness of 3 nm, obtaining the ultraviolet absorption enhanced semiconductor film.

[0058] Example 3

[0059] This example provides an ultraviolet absorption enhanced semiconductor film. The structural schematic diagram of the ultraviolet absorption enhanced semiconductor film is as Figure 1 shown. The ultraviolet absorption enhanced semiconductor film includes a sapphire substrate 1 with a thickness of 500 μm and an aluminum intermediate layer 2 with a thickness of 100 nm and an aluminum nitride dielectric layer 3 with a thickness of 10 nm that are sequentially stacked on the surface of the sapphire substrate 1. The ultraviolet absorption enhanced semiconductor film is obtained by the following method:

[0060] (1) Use a substrate cooling system to control the temperature of a sapphire substrate with a thickness of 500 μm at 50 °C. Adopt molecular beam epitaxy. The sapphire substrate is inverted and perpendicular to the aluminum source, and rotates at a rotation speed of 6 revolutions per minute. Control high-purity aluminum to deposit at a speed of 1 nm / s for 100 s to form an aluminum intermediate layer with a thickness of 100 nm, obtaining a semi-finished film;

[0061] (2) Through a vacuum interconnection system, transfer the semi-finished film to a plasma-enhanced atomic layer deposition system. Heat the semi-finished film to 350 °C. Use argon with a flow rate of 15 sccm as the carrier gas to introduce trimethylaluminum into the plasma-enhanced atomic layer deposition system. Generate plasma nitrogen, plasma argon, and plasma hydrogen from nitrogen, argon, and hydrogen. Introduce plasma nitrogen, plasma argon, and plasma hydrogen into the plasma-enhanced atomic layer deposition system at flow rates of 2 sccm, 3 sccm, and 15 sccm respectively. React for 60 minutes at a power of 250 W to form an aluminum nitride dielectric layer with a thickness of 10 nm, obtaining the ultraviolet absorption enhanced semiconductor film.

[0062] Example 4

[0063] The difference between this example and Example 1 is only that the thickness of the aluminum nitride dielectric layer in the ultraviolet absorption enhanced semiconductor thin film is 1 nm, and other conditions and parameters are exactly the same as those in Example 1 (the preparation parameters need to be appropriately adjusted according to the thickness of the aluminum nitride dielectric layer).

[0064] Example 5

[0065] The difference between this example and Example 1 is only that the thickness of the aluminum nitride dielectric layer in the ultraviolet absorption enhanced semiconductor thin film is 2 nm, and other conditions and parameters are exactly the same as those in Example 1 (the preparation parameters need to be appropriately adjusted according to the thickness of the aluminum nitride dielectric layer).

[0066] Example 6

[0067] The difference between this example and Example 1 is only that the thickness of the aluminum nitride dielectric layer in the ultraviolet absorption enhanced semiconductor thin film is 6 nm, and other conditions and parameters are exactly the same as those in Example 1 (the preparation parameters need to be appropriately adjusted according to the thickness of the aluminum nitride dielectric layer).

[0068] Example 7

[0069] The difference between this example and Example 1 is only that the thickness of the aluminum nitride dielectric layer in the ultraviolet absorption enhanced semiconductor thin film is 8 nm, and other conditions and parameters are exactly the same as those in Example 1 (the preparation parameters need to be appropriately adjusted according to the thickness of the aluminum nitride dielectric layer).

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 2 is only that the aluminum intermediate layer is replaced with a silver intermediate layer, and other conditions and parameters are exactly the same as those in Example 2 (the preparation parameters need to be appropriately adjusted according to the type of the intermediate layer).

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 2 is only that the aluminum intermediate layer is replaced with a gold intermediate layer, and other conditions and parameters are exactly the same as those in Example 2 (the preparation parameters need to be appropriately adjusted according to the type of the intermediate layer).

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 2 is only that the aluminum intermediate layer is replaced with an aluminum oxide intermediate layer, and other conditions and parameters are exactly the same as those in Example 2 (the preparation parameters need to be appropriately adjusted according to the type of the intermediate layer).

[0076] Comparative Example 4

[0077] The difference between this comparative example and Example 3 is only that the aluminum intermediate layer is replaced with a silver intermediate layer, and other conditions and parameters are exactly the same as those in Example 3 (the preparation parameters need to be appropriately adjusted according to the type of intermediate layer).

[0078] Comparative Example 5

[0079] The difference between this comparative example and Example 3 is only that the aluminum intermediate layer is replaced with a gold intermediate layer, and other conditions and parameters are exactly the same as those in Example 3 (the preparation parameters need to be appropriately adjusted according to the type of intermediate layer).

[0080] Comparative Example 6

[0081] The difference between this comparative example and Example 3 is only that the aluminum intermediate layer is replaced with an alumina intermediate layer, and other conditions and parameters are exactly the same as those in Example 3 (the preparation parameters need to be appropriately adjusted according to the type of intermediate layer).

[0082] Comparative Example 7

[0083] The difference between this comparative example and Example 1 is only that the vacuum interconnection system is not used, and other conditions and parameters are exactly the same as those in Example 1.

[0084] Performance test:

[0085] Take the semiconductor thin films prepared in the examples and comparative examples, and use the FDTD simulation calculation software, because it can add monitors to obtain the absorption rate of the AlN layer. The subsequent experimental data is expected to be tested for reflection and transmission using a PerkinElmer Lambda 950 ultraviolet-visible spectrophotometer, and the maximum light absorption rate of the semiconductor thin film is recorded. The test results are shown in Table 1:

[0086] Table 1

[0087]

[0088] As can be seen from Table 1, from Examples 1-7, it can be obtained that the maximum light absorption rate of the ultraviolet absorption-enhanced semiconductor thin film described in the present invention can reach more than 49.5%, and by adjusting the thickness of the aluminum nitride layer, the maximum light absorption rate of the ultraviolet absorption-enhanced semiconductor thin film can reach 90%.

[0089] The reflection comparison curves of the ultraviolet absorption-enhanced semiconductor thin films prepared in Examples 1, 3-7 are as Figure 2 shown. From the comparison of Examples 1, 3-7, it can be obtained that as the thickness of the aluminum nitride dielectric layer on the aluminum intermediate layer increases, the absorption rate of the aluminum nitride dielectric layer first increases and then decreases. This is because the vector sum of the absorption phase shift and the interface phase shift in this structure results in the phase difference of the reflected light on the surface of the aluminum nitride dielectric layer not being an odd multiple of π, so that the incident light cannot be better captured.

[0090] The comparison diagrams of the light absorption curves of the ultraviolet absorption-enhanced semiconductor films prepared in Example 2 and Comparative Examples 1-3 are as follows Figure 3 shown. The comparison diagrams of the light absorption curves of the ultraviolet absorption-enhanced semiconductor films prepared in Example 3 and Comparative Examples 4-6 are as follows Figure 4 shown. By comparing Example 2 with Comparative Examples 1-3 and Example 3 with Comparative Examples 4-6, it can be obtained that the reflection of the aluminum nitride dielectric layer on metals Au, Ag, and Al is very small. Therefore, by adding a monitor and setting it before the aluminum nitride dielectric layer and the substrate, the transmittance T is obtained. Through A = 1–R–T, the absorption of the aluminum nitride dielectric layer is as shown in the figure. It can be found that the 3-nm aluminum nitride dielectric layer will enhance the absorption on the metal, and the absorption is the largest on the aluminum intermediate layer, achieving nearly 86% absorption under the irradiation of 157-nm incident light. The ultraviolet absorption-enhanced semiconductor film with a 10-nm aluminum nitride dielectric layer achieves nearly 86% absorption at 196 nm. The reason may be the surface plasmon effect of the aluminum intermediate layer, that is, when the incident light frequency matches the vibration frequency of the free electrons on the Al metal surface, a strong local electromagnetic field enhancement effect will occur, while the plasmon resonance wavelengths of Au and Ag are usually in the visible to infrared bands.

[0091] The applicant declares that the above description is only the specific implementation manners of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A semiconductor film with enhanced ultraviolet absorption, characterized in that: The ultraviolet absorption enhanced semiconductor film comprises a substrate and an aluminum intermediate layer and an aluminum nitride dielectric layer which are sequentially stacked on a surface of one side of the substrate; The thickness of the aluminum intermediate layer is 100nm-150nm, and the thickness of the aluminum nitride dielectric layer is 3nm-10nm.

2. The ultraviolet absorption enhanced semiconductor film according to claim 1, characterized in that: The substrate includes a sapphire substrate.

3. The ultraviolet absorption enhanced semiconductor film according to claim 1, characterized in that: The thickness of the substrate is 400 μm-500 μm.

4. A method for preparing a semiconductor film with enhanced ultraviolet absorption as claimed in any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) depositing a first aluminum source on a substrate by molecular beam epitaxy to form an aluminum intermediate layer to obtain a semi-finished film; (2) The semi-finished film is transferred to a plasma enhanced atomic layer deposition system, the second aluminum source is brought into the plasma enhanced atomic layer deposition system through a carrier gas, and plasma nitrogen is introduced into the plasma enhanced atomic layer deposition system. The plasma nitrogen reacts with the second aluminum source chemically adsorbed on the surface of the aluminum intermediate layer of the semi-finished film to undergo a nitridation reaction, and aluminum nitride is deposited on the aluminum intermediate layer of the semi-finished film to form an aluminum nitride dielectric layer, thereby obtaining the ultraviolet absorption enhanced semiconductor film.

5. The preparation method according to claim 4, characterized in that: Step (1) The first aluminum source includes high-purity aluminum.

6. The preparation method according to claim 4, characterized in that: The substrate is cooled before the molecular beam epitaxy in step (1).

7. The preparation method according to claim 6, characterized in that: After the temperature reduction treatment, the temperature of the substrate is 25°C to 80°C.

8. The preparation method according to claim 4, characterized in that: The deposition rate of the molecular beam epitaxy in step (1) is 0.5 nm / s to 1.5 nm / s.

9. The preparation method according to claim 4, characterized in that: The time of the molecular beam epitaxy in step (1) is 1 min to 3 min.

10. The preparation method according to claim 4, characterized in that: During the molecular beam epitaxy process of step (1), the surface of the substrate to be evaporated is inverted and parallel to the evaporation source, and rotates at a speed of 4 turns / min to 6 turns / min.

11. The preparation method according to claim 4, characterized in that: Step (2) transfers the semi-finished film to a plasma enhanced atomic layer deposition system through a vacuum interconnect to deposit aluminum nitride.

12. The preparation method according to claim 4, characterized in that: In step (2), before the second aluminum source is brought into the plasma enhanced atomic layer deposition system via the carrier gas, the semi-finished film is heated.

13. The preparation method according to claim 12, characterized in that: After the heating treatment, the temperature of the semi-finished film is 300°C to 350°C.

14. The preparation method according to claim 4, characterized in that: Step (2) The second aluminum source includes trimethylaluminum.

15. The preparation method according to claim 4, characterized in that: The carrier gas for the plasma enhanced atomic layer deposition in step (2) includes argon.

16. The preparation method according to claim 15, characterized in that: The flow rate of the argon gas is 15 sccm-20 sccm.

17. The preparation method according to claim 4, characterized in that: The flow rate of the plasma nitrogen in step (2) is 2 sccm to 8 sccm.

18. The preparation method according to claim 4, characterized in that: In step (2), while introducing plasma nitrogen into the plasma enhanced atomic layer deposition system, argon plasma and hydrogen plasma are also introduced.

19. The preparation method according to claim 18, characterized in that: The flow rate of the argon plasma is 3 sccm-5 sccm.

20. The preparation method according to claim 18, characterized in that: The flow rate of the hydrogen plasma is 15 sccm-25 sccm.

21. The preparation method according to claim 4, characterized in that: The power of the plasma enhanced atomic layer deposition in step (2) is 250W~350W.

22. A photoelectric detector, characterized in that: The photodetector comprises the ultraviolet absorption enhanced semiconductor film as described in any one of claims 1 to 3.

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