Locally doped lithium niobate film and preparation method and application thereof

Abstract

The invention provides a locally doped lithium niobate film and a preparation method and application thereof, and belongs to the field of integrated optics. The method comprises the following steps: locally coating a film on the surface of a lithium niobate wafer by a magnetron sputtering method, diffusing the locally coated lithium niobate wafer in a lithium-deficient crucible, and preparing the locally doped lithium niobate film by utilizing a Smart-cuting technology. The preparation method disclosed by the invention is simple in process, the problem that the film cannot be customized in the local area of the surface of the lithium niobate wafer in the prior art is solved, and the problems of alignment, interface loss and the like during splicing of active and passive films are also solved.

Description

Technical Field

[0001] The invention belongs to the field of integrated optics, and in particular relates to a locally doped lithium niobate film and a preparation method and application thereof. Background Art

[0002] Lithium niobate crystal (LN) is a multifunctional artificial crystal with excellent electro-optical, acousto-optical and nonlinear optical properties. It has long been considered as one of the priority candidate platform materials for photonic integration. Thanks to the preparation and commercialization of single-crystal lithium niobate thin films on insulators (LNOI) with submicron thickness and the development of supporting micro-nano processing technology, a series of achievements have been made in the research of micro-nano photonic devices based on LNOI, such as delay lines, high-speed electro-optic modulators and electro-optic frequency combs.

[0003] By doping LNOI with rare earth ions, waveguide amplifiers and lasers with optical gain capabilities can be realized. Integrating such active and passive devices on a chip can meet the needs of a series of on-chip integrated photonic systems such as loss compensation, power enhancement and functional integration.

[0004] At present, the existing technology is to directly splice LNOI and LNOI doped with rare earth ions together to prepare active and passive integrated lithium niobate thin films. This technology has the following disadvantages: ①High difficulty and complex process.

[0005] ② Because the splicing cannot be 100% aligned and there is a height difference, light will be lost after passing through, causing alignment and interface losses, which in turn affects the performance of devices made of active and passive integrated lithium niobate thin films and reduces the transmission efficiency of light in the device.

[0006] ③ Due to the use of curing glue, the curing glue is affected by light, heat, oxygen and chemical media in the environment, which will cause changes in the internal structure, resulting in aging of the curing glue, and then causing the performance of active and passive integrated devices prepared with lithium niobate thin films to be unstable.

[0007] ④ The shape of the diffusion region cannot be customized, which limits the integration method with the device. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a locally doped lithium niobate film and a preparation method and application thereof.

[0009] The technical solution of the present invention to solve the above technical problem is as follows: A method for preparing a locally doped lithium niobate film, comprising:

[0010] Step 1: Locally coat the surface of lithium niobate wafer by magnetron sputtering.

[0011] Take a clean lithium niobate wafer with a diameter of 3 to 8 inches and a thickness of 0.5 to 1 mm, wherein the molar ratio of [Li] to [Li+Nb] in the lithium niobate wafer is 45% to 52%, cover the area on the lithium niobate wafer that does not need to be coated with a glass slide and high-temperature glue to form a mask, then fix the lithium niobate wafer on the sample holder of the magnetron sputtering instrument, replace the target material in the cavity with an Er target, evacuate, and wait until the pressure in the cavity drops to 10 -4 After Pa, the current is controlled to 200~300mA, and the coating is carried out for 5~10min. After the coating is completed, the magnetron sputtering instrument is turned off. After the sample is cooled in the cavity, it is taken out to obtain a lithium niobate wafer with a localized Er film coated on the surface. The thickness of the Er film is 70~300nm.

[0012] Step 1: The position of the Er film is customized on the local area of ​​the surface of the lithium niobate wafer by magnetron sputtering. Under the same diffusion conditions, the thickness of the Er film can be controlled by controlling the time and current of the magnetron sputtering.

[0013] Step 2: The locally coated lithium niobate wafer is diffused in a lithium-deficient crucible.

[0014] A layer of lithium niobate grains with a diameter of 0.45-0.6 mm is spread on the bottom of the lithium-deficient crucible, and an Al2O3 wafer, a lithium niobate wafer obtained in step 1, and an Al2O3 wafer are placed on the lithium niobate grains in sequence, and a lithium-deficient crucible lid is placed on the lithium-deficient crucible, and lithium-deficient lithium niobate powder is spread around the lid to form a closed lithium-deficient atmosphere, wherein the diameter of the Al2O3 wafer is greater than or equal to the diameter of the lithium niobate wafer obtained in step 1.

[0015] After the production is completed, the platinum crucible cover is put on, and the entire crucible is placed in a muffle furnace and diffused at 1100-1200°C for 80-230 hours to obtain a lithium niobate wafer locally doped with Er, wherein the Er concentration in the lithium niobate wafer is 0.3 mol%-2 mol%.

[0016] The lithium niobate wafer locally doped with Er is subjected to chemical mechanical polishing until the surface roughness is less than 1 nm, thereby obtaining a polished lithium niobate wafer.

[0017] Step 2: Use the lithium-deficient crucible and the lithium-deficient crucible cover to provide a lithium-deficient atmosphere for diffusion, place the locally coated lithium niobate wafer between two Al2O3 wafers of the same size, and fix the lithium niobate wafer in the middle to prevent it from deforming during high-temperature diffusion. Lithium niobate grains with a diameter of 0.45-0.6 mm are laid on the bottom of the lithium-deficient crucible to prevent the lithium niobate wafer and the Al2O3 wafer from contacting the residual lithium-deficient lithium niobate powder on the surface of the lithium-deficient crucible and reacting during the heating process. The above-mentioned lithium-deficient crucible and lithium-deficient crucible cover can be purchased commercially or prepared by yourself.

[0018] Step 3: Prepare locally doped lithium niobate thin film using Smart-cutting technology.

[0019] Helium ions are implanted into the lithium niobate wafer obtained in step 2 by an ion implantation method, thereby forming a thin film layer, a separation layer and a residual material layer in the lithium niobate wafer from top to bottom, wherein the implanted helium ions are distributed in the separation layer, the helium ion implantation energy is 10-20000keV, and the thickness of the thin film layer is 25-4500nm. The lithium niobate wafer after ion implantation is heated at 200-450°C for 1-5h to heat the lithium niobate wafer evenly and to allow the helium ions distributed in the separation layer to obtain energy that allows the helium ions to form bubbles but does not cause the thin film layer to fall off or be damaged, thereby obtaining a heated lithium niobate wafer.

[0020] A 400µm thick Si wafer was taken, and a 2µm thick SiO2 layer was prepared on the Si wafer using plasma enhanced chemical vapor deposition (PECVD) to obtain a substrate layer, wherein the power was 150W, the pressure was 500mTorr, and the temperature was 25°C, and the substrate layer was chemically mechanically polished to a surface roughness of less than 1nm.

[0021] At room temperature, the heated lithium niobate wafer and the substrate layer are bonded by a wafer bonding method to obtain a bonded body with a five-layer structure, which is, from top to bottom: a lithium niobate wafer residual material layer, a separation layer, a thin film layer, a silicon dioxide layer and a silicon layer. The bonded body is placed in an autoclave and heated at 50-190°C for 1-150h to separate the thin film layer and the residual material layer to obtain a separated body with a three-layer structure, which is, from top to bottom: a thin film layer, a silicon dioxide layer and a silicon layer.

[0022] The separated body is heated at 250-550°C for 1-10 hours for annealing, and then the thin film layer is chemically mechanically polished to a target thickness to obtain a locally doped lithium niobate thin film with a target thickness LN layer, a 2µm SiO2 layer, and a 400µm Si layer bonded together.

[0023] Smart-cutting technology is an important technology in the field of semiconductor processing. This technology mainly achieves high-precision transfer and cutting of thin-layer materials on wafers through steps such as ion implantation, wafer bonding, brittle layer formation and stress-induced peeling. Smart slicing technology is widely used in integrated circuits, micro-electromechanical systems (MEMS), solar cells and other fields, playing an important role in improving production efficiency, reducing costs, and ensuring high product quality and flatness.

[0024] Based on the above technical solution, the present invention can also be improved as follows.

[0025] Further, in step 1, the molar ratio of [Li] to [Li+Nb] in the lithium niobate wafer is 47% to 50%, preferably 48% to 49%, and more preferably 48.6%. The diameter of the lithium niobate wafer is 3 inches and the thickness is 1 mm. The lithium niobate wafer used in the present invention is prepared by itself or purchased from the market, such as a commercially available lithium niobate wafer with the same composition.

[0026] Furthermore, in step 1, the high temperature glue is a polyimide glue with a temperature resistance of 250-300°C.

[0027] Further, in step 1, the Er target can be replaced by a Mg target, a Fe target, a Zr target, a Bi target, a Yb target or a Nd target.

[0028] Furthermore, in step 1, the sample is cooled in the chamber for 1 to 2 hours.

[0029] Further, in step 2, the lithium-deficient crucible and the lithium-deficient crucible cover are prepared by a high-temperature solid phase method: Li2CO3 and Nb2O5 with a purity of 99.99% were mixed in a molar ratio of 40mol%:60mol%, and fully ground and mixed on a star ball mill at 300r / min for 2h. The mixture was calcined at 1100℃ for 1h to allow the mixture to undergo a solid phase reaction to obtain lithium-deficient lithium niobate powder.

[0030] Take 800g of lithium-deficient lithium niobate powder, put it in a platinum crucible, and use a mold to compact the powder into a groove with a diameter of 80mm and a depth of 20mm to obtain a lithium-deficient crucible.

[0031] Take 400g of lithium-deficient lithium niobate powder and compact it into a cylinder with a diameter of 100mm and a height of 12mm using a hydraulic press to obtain a lithium-deficient crucible cover.

[0032] The lithium-deficient crucible and the lithium-deficient crucible cover were calcined at 1150° C. for 7 hours to solidify them.

[0033] Furthermore, in step 2, the diameter of the Al2O3 wafer is the same as the diameter of the lithium niobate wafer obtained in step 1, and the thickness is 0.5 mm.

[0034] Furthermore, in step 2, the lithium-deficient lithium niobate powder is prepared by the following method: Li2CO3 with a purity of 99.99% and Nb2O5 are mixed in a molar ratio of 40mol%:60mol%, fully ground and mixed on a star ball mill at 300r / min for 2h, and calcined at 1100°C for 1h to allow the mixture to undergo a solid phase reaction to obtain lithium-deficient lithium niobate powder.

[0035] Further, in step 2, the crucible is placed in a muffle furnace and diffused at 1100° C. for 80 hours.

[0036] Furthermore, in step 2, the diffusion layer on the surface of the lithium niobate wafer locally doped with Er is polished to disappear.

[0037] The beneficial effects of adopting this step are: the purpose of chemical mechanical polishing is to remove the diffusion layer, flatten the surface, and reduce the roughness of the wafer surface.

[0038] Furthermore, in step 3, the locally doped lithium niobate film is divided into small pieces of 1 cm in length and 1.5 cm in width, so as to facilitate micro-nano processing to prepare multifunctional integrated devices.

[0039] The present invention also provides a locally doped lithium niobate film prepared by the above method, wherein the locally doped lithium niobate film has a diameter of 3 to 8 inches and a roughness of less than 1 nm.

[0040] The present invention further provides a locally doped lithium niobate film as described above for use in preparing integrated optoelectronic devices, including integrated waveguides, lasers, amplifiers, electro-optic modulators, and photodetectors.

[0041] The present invention further provides an integrated waveguide, comprising the above-mentioned locally doped lithium niobate film.

[0042] The present invention further provides an integrated laser, comprising the above-mentioned locally doped lithium niobate film.

[0043] The present invention further provides an integrated amplifier, comprising the above-mentioned locally doped lithium niobate film.

[0044] The present invention further provides an integrated electro-optic modulator, comprising the above-mentioned locally doped lithium niobate film.

[0045] The present invention further provides an integrated photodetector, comprising the above-mentioned locally doped lithium niobate film.

[0046] The beneficial effects of the present invention are: The present invention prepares a locally doped lithium niobate film based on a diffusion method, has a simple process, overcomes the disadvantage of the prior art that the shape of the diffusion region cannot be customized, and customizes the shape of the diffusion region by designing a mask pattern, which has the advantage of local customization. In addition, when integrating devices on the lithium niobate film, different diffusion region shapes can meet the integration of devices with different functions.

[0047] The present invention prepares locally doped lithium niobate thin films based on the diffusion method, and has no problems such as alignment and interface loss, which fully ensures the compactness, high efficiency and stability of the integrated optical system. At the same time, it can improve production efficiency and reduce production costs, fill the gap in the integration of monolithic LNOI active-passive devices, and greatly promote the development of large-scale high-performance on-chip photonic devices.

[0048] The present invention prepares a locally doped lithium niobate film based on a diffusion method. Since the method does not use a curing glue, there is no problem of curing glue aging.

[0049] The locally doped lithium niobate film prepared by the present invention is large-sized and optical-grade, that is, the diameter is ≥3 inches and the roughness is <1nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is the Raman spectrum of different regions of the locally doped lithium niobate film prepared in Example 1 under excitation at a wavelength of 532 nm.

[0052] Figure 2 This is the fluorescence intensity distribution diagram of different regions of the locally doped Er lithium niobate film prepared in Example 1. DETAILED DESCRIPTION

[0053] The high temperature adhesive used in the following examples is purchased from commercially available high temperature resistant PI polyimide high temperature insulating tape. Example 1

[0054] Step 1: Locally coat the surface of lithium niobate wafer by magnetron sputtering.

[0055] Take a clean lithium niobate wafer with a diameter of 3 inches and a thickness of 1 mm. The molar ratio of [Li] to [Li+Nb] in the lithium niobate wafer is 48.6%. Cover the area on the lithium niobate wafer that does not need to be coated with a glass slide and high-temperature glue to form a mask. Then fix the lithium niobate wafer on the sample holder of the magnetron sputtering instrument, replace the target material in the cavity with an Er target, and evacuate the cavity until the pressure in the cavity drops to 10 -4 After Pa, the current was controlled to 200mA and the coating was carried out for 5min. After the coating was completed, the magnetron sputtering instrument was turned off. After the sample was cooled in the chamber for 1-2h, it was taken out to obtain a lithium niobate wafer with a localized Er film on the surface. The thickness of the Er film was 80nm.

[0056] Step 2: The locally coated lithium niobate wafer is diffused in a lithium-deficient crucible.

[0057] 2.1) Prepare lithium-deficient crucibles and lithium-deficient crucible covers by high-temperature solid phase method to create a lithium-deficient atmosphere.

[0058] Li2CO3 and Nb2O5 with a purity of 99.99% were mixed in a molar ratio of 40mol%:60mol%, and fully ground and mixed on a star ball mill at 300r / min for 2h. The mixture was calcined at 1100℃ for 1h to allow the mixture to undergo a solid phase reaction to obtain lithium-deficient lithium niobate powder.

[0059] Take 800g of lithium-deficient lithium niobate powder, put it in a platinum crucible, and use a mold to compact the powder into a groove with a diameter of 80mm and a depth of 20mm to obtain a lithium-deficient crucible.

[0060] Take 400g of lithium-deficient lithium niobate powder and compact it into a cylinder with a diameter of 100mm and a height of 12mm using a hydraulic press to obtain a lithium-deficient crucible cover.

[0061] The lithium-deficient crucible and the lithium-deficient crucible cover were calcined at 1150° C. for 7 hours to solidify them.

[0062] 2.2) Place the lithium niobate wafer with localized surface coating in a lithium-deficient crucible for diffusion.

[0063] A layer of lithium niobate grains with a diameter of 0.45-0.6mm is placed on the bottom of the lithium-deficient crucible to prevent the lithium niobate wafer, Al2O3 wafer and the residual lithium-deficient lithium niobate powder on the surface of the lithium-deficient crucible from contacting and reacting during the heating process. Al2O3 wafers, lithium niobate wafers obtained in step 1 and Al2O3 wafers are placed on the lithium niobate grains in sequence. The diameter of the Al2O3 wafer is 3 inches and the thickness is 0.5mm. The two Al2O3 wafers are used to fix the lithium niobate wafer in the middle to reduce its deformation during high-temperature diffusion.

[0064] The lithium-deficient crucible cover is placed on the lithium-deficient crucible, and lithium-deficient lithium niobate powder is spread around the cover to form a closed lithium-deficient atmosphere.

[0065] After the production is completed, the platinum crucible cover is put on, and the entire crucible is placed in a muffle furnace and diffused at 1100° C. for 80 hours to obtain a lithium niobate wafer locally doped with Er, wherein the Er concentration in the lithium niobate wafer is 0.3 mol%.

[0066] The lithium niobate wafer locally doped with Er is subjected to chemical mechanical polishing until the diffusion layer on the surface of the lithium niobate wafer disappears and the surface roughness is less than 1 nm, thereby obtaining a polished lithium niobate wafer.

[0067] Step 3: Prepare locally doped lithium niobate thin film using Smart-cutting technology

[0068] Helium ions are implanted into the lithium niobate wafer obtained in step 2 by ion implantation, thereby forming a thin film layer, a separation layer and a residual material layer in the lithium niobate wafer from top to bottom, wherein the implanted helium ions are distributed in the separation layer, the helium ion implantation energy is 6000keV, and the thickness of the thin film layer is 700nm. The lithium niobate wafer after ion implantation is heated at 220°C for 3h to make the lithium niobate wafer evenly heated and the helium ions distributed in the separation layer obtain energy that allows the helium ions to form bubbles but does not cause the thin film layer to fall off or be damaged, thereby obtaining a heated lithium niobate wafer.

[0069] A 400µm thick Si wafer was taken, and a 2µm thick SiO2 layer was prepared on the Si wafer using plasma enhanced chemical vapor deposition (PECVD) to obtain a substrate layer, wherein the power was 150W, the pressure was 500mTorr, and the temperature was 25°C, and the substrate layer was chemically mechanically polished to a surface roughness of less than 1nm.

[0070] At room temperature, the heated lithium niobate wafer and the substrate layer are bonded by a wafer bonding method to obtain a bonded body with a five-layer structure, which are, from top to bottom: a lithium niobate wafer residual material layer, a separation layer, a thin film layer, a silicon dioxide layer and a silicon layer. The bonded body is placed in an autoclave and heated at 95°C for 10 hours to separate the thin film layer and the residual material layer, thereby obtaining a separated body with a three-layer structure, which are, from top to bottom: a thin film layer, a silicon dioxide layer and a silicon layer.

[0071] The separated body was heated at 400°C for 5 hours for annealing, and then the thin film layer was chemically mechanically polished to 600nm to obtain a locally doped lithium niobate film with a 600nm LN layer, a 2µm SiO2 layer, and a 400µm Si layer bonded together.

[0072] The locally doped lithium niobate film has a diameter of 3 inches, a roughness of <1 nm, and an Er doping concentration of 0.3 mol%. Figure 1 The spectral data show that the Raman signal in the active region comes from the fluorescence signal of Er ions, indicating that Er 3+ is incorporated into localized areas of the film.

[0073] The fluorescence intensity distribution of different regions of the locally doped Er lithium niobate film is shown in Figure 2. Figure 2 As shown, it is shown that the active area and the passive area of ​​the locally doped lithium niobate film prepared by the diffusion method have a clear interface, there is no alignment problem during splicing, and it can be used for micro-nano processing to prepare multifunctional integrated devices.

[0074] The preparation methods of Examples 2-8 are the same as those of Example 1, except that the magnetron current, Er film thickness, diffusion time, and Er concentration are different, and the specific parameters are shown in Table 1. Examples 2-8 can all obtain locally doped lithium niobate thin films with a thickness of 600nm LN layer, 2µm SiO2 layer, and 400µm Si layer bonded together, and the diameter of the locally doped lithium niobate thin films is 3 inches, and the roughness is less than 1nm.

[0075] The locally doped lithium niobate film prepared in Example 2-8 was tested, and the spectral data showed that the Raman signal in the active region came from the fluorescence signal of Er ions, indicating that Er 3+The fluorescence intensity distribution data show that the active area and the passive area of ​​the lithium niobate film have a clear interface, and there is no alignment problem during splicing. Among them, the locally doped lithium niobate film prepared in Example 8 has the best effect when used as an integrated optoelectronic device because the doping concentration of Er in the film is the highest.

[0076] Table 1

[0077] Example Magnetron current (mA) Coating time (min) Diffusion temperature (℃) Diffusion time (h) Er film thickness (nm) Er concentration (mol%) 1 200 5 1100 80 80 0.3 2 200 5 1100 130 80 0.6 3 200 5 1100 180 80 1.2 4 200 5 1100 230 80 1.8 5 300 5 1100 80 150 0.5 6 300 5 1100 130 150 1.0 7 300 5 1100 180 150 1.5 8 300 5 1100 230 150 2.0

Claims

1. A method for preparing a locally doped lithium niobate thin film, characterized in that: include: Step 1: Magnetron sputtering to locally coat the surface of lithium niobate wafer Take a clean lithium niobate wafer with a diameter of 3 to 8 inches and a thickness of 0.5 to 1 mm, wherein the molar ratio of [Li] to [Li+Nb] in the lithium niobate wafer is 45% to 52%, cover the area on the lithium niobate wafer that does not need to be coated with a glass slide and high-temperature glue to form a mask, then fix the lithium niobate wafer on the sample holder of the magnetron sputtering instrument, replace the target material in the cavity with an Er target, evacuate, and wait until the pressure in the cavity drops to 10 -4 After Pa, the current is controlled to be 200-300 mA, and the coating is carried out for 5-10 minutes. After the coating is completed, the magnetron sputtering instrument is turned off, and the sample is taken out after cooling in the chamber to obtain a lithium niobate wafer with a local Er film on the surface. The thickness of the Er film is 70-300 nm. Step 2: Locally coated lithium niobate wafer is diffused in a lithium-deficient crucible A layer of lithium niobate grains with a diameter of 0.45-0.6 mm is laid on the bottom of the lithium-deficient crucible, and an Al2O3 wafer, a lithium niobate wafer obtained in step 1, and an Al2O3 wafer are placed on the lithium niobate grains in sequence, and a lithium-deficient crucible cover is placed on the lithium-deficient crucible, and lithium-deficient lithium niobate powder is spread around the cover to form a closed lithium-deficient atmosphere, wherein the diameter of the Al2O3 wafer is greater than or equal to the diameter of the lithium niobate wafer obtained in step 1; After the production is completed, the platinum crucible cover is put on, and the entire crucible is placed in a muffle furnace and diffused at 1100-1200°C for 80-230 hours to obtain a lithium niobate wafer locally doped with Er, wherein the Er concentration in the lithium niobate wafer is 0.3mol%-2mol%; Chemically mechanically polishing the lithium niobate wafer locally doped with Er until the surface roughness is less than 1 nm, thereby obtaining a polished lithium niobate wafer; Step 3: Prepare locally doped lithium niobate thin film using Smart-cutting technology By ion implantation, helium ions are implanted into the lithium niobate wafer obtained in step 2, thereby forming a thin film layer, a separation layer and a residual material layer in the lithium niobate wafer from top to bottom, wherein the implanted helium ions are distributed in the separation layer, the helium ion implantation energy is 10-20000keV, the thickness of the thin film layer is 25-4500nm, and the lithium niobate wafer after ion implantation is heated at 200-450°C for 1-5h to obtain a heated lithium niobate wafer; A 400µm thick Si wafer was taken, and a layer of SiO2 with a thickness of 2µm was prepared on the Si wafer by plasma enhanced chemical vapor deposition to obtain a substrate layer, wherein the power was 150W, the pressure was 500mTorr, and the temperature was 25°C, and the substrate layer was chemically mechanically polished until the surface roughness was less than 1nm; At room temperature, a heated lithium niobate wafer and a substrate layer are bonded by a wafer bonding method to obtain a bonded body with a five-layer structure, which is, from top to bottom, a lithium niobate wafer residual material layer, a separation layer, a thin film layer, a silicon dioxide layer and a silicon layer; the bonded body is placed in an autoclave and heated at 50-190° C. for 1-150 hours to separate the thin film layer and the residual material layer, to obtain a separated body with a three-layer structure, which is, from top to bottom, a thin film layer, a silicon dioxide layer and a silicon layer; The separated body is heated at 250-550°C for 1-10 hours for annealing, and then the thin film layer is chemically mechanically polished to a target thickness to obtain a locally doped lithium niobate thin film with a target thickness LN layer, a 2µm SiO2 layer, and a 400µm Si layer bonded together.

2. The preparation method according to claim 1, characterized in that: In step 1, The molar ratio of [Li] to [Li+Nb] in the lithium niobate wafer is 47% to 50%; The lithium niobate wafer has a diameter of 3 inches and a thickness of 1 mm; The high temperature glue is a polyimide glue with a temperature resistance of 250-300°C; The Er target can be replaced by a Mg target, a Fe target, a Zr target, a Bi target, a Yb target or a Nd target; The sample is cooled in the chamber for 1 to 2 hours.

3. The preparation method according to claim 1, characterized in that: In step 2, the lithium-deficient crucible and the lithium-deficient crucible cover are prepared by a high-temperature solid phase method: Li2CO3 and Nb2O5 with a purity of 99.99% were mixed in a molar ratio of 40mol%:60mol%, fully ground and mixed for 2h at 300r / min on a star ball mill, and calcined at 1100℃ for 1h to allow the mixture to fully undergo solid phase reaction to obtain lithium-deficient lithium niobate powder; Take 800g of lithium-deficient lithium niobate powder, put it in a platinum crucible, and use a mold to compact the powder into a groove with a diameter of 80mm and a depth of 20mm to obtain a lithium-deficient crucible; Take 400g of lithium-deficient lithium niobate powder and compact it into a cylinder with a diameter of 100mm and a height of 12mm using a hydraulic press to obtain a lithium-deficient crucible cover; The lithium-deficient crucible and the lithium-deficient crucible cover were calcined at 1150° C. for 7 hours to solidify them.

4. The preparation method according to claim 1, characterized in that: In step 2, The diameter of the Al2O3 wafer is the same as the diameter of the lithium niobate wafer obtained in step 1, and the thickness is 0.5 mm; The lithium-deficient lithium niobate powder is prepared by the following method: Li2CO3 with a purity of 99.99% and Nb2O5 are mixed in a molar ratio of 40mol%:60mol%, fully ground and mixed at 300r / min for 2h on a star ball mill, and calcined at 1100°C for 1h to allow the mixture to fully undergo solid phase reaction to obtain lithium-deficient lithium niobate powder; The crucible is placed in a muffle furnace and diffused at 1100° C. for 80 h; The diffusion layer on the surface of the lithium niobate wafer polished to local doping with Er disappears.

5. A locally doped lithium niobate film obtained by the method according to any one of claims 1 to 4, characterized in that: The locally doped lithium niobate film has a diameter of 3 to 8 inches and a roughness of less than 1 nm.

6. A locally doped lithium niobate film as claimed in claim 5 for use in preparing integrated optoelectronic devices, including integrated waveguides, lasers, amplifiers, electro-optic modulators, and photodetectors.

7. An integrated waveguide, characterized in that: Including the locally doped lithium niobate film as described in claim 5.

8. An integrated laser, characterized in that: Including the locally doped lithium niobate film as described in claim 5.

9. An integrated amplifier, characterized in that: Including the locally doped lithium niobate film as described in claim 5.

10. An integrated electro-optic modulator, characterized in that: Including the locally doped lithium niobate film as described in claim 5.

11. An integrated photodetector, characterized in that: Including the locally doped lithium niobate film as described in claim 5.

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