In-situ integration method for rare earth doped two-dimensional material on surface of lithium niobate micro-nano structure

Abstract

The invention relates to the technical field of integrated photonics and two-dimensional material device manufacturing, in particular to an in-situ integration method of a rare earth doped two-dimensional material on the surface of a lithium niobate micro-nano structure. Comprising the following steps: pretreating a lithium niobate micro-nano structure substrate; a sub-nano metal layer is deposited through high-vacuum magnetron sputtering, and the thickness of the sub-nano metal layer is smaller than 1 nm; performing low-temperature annealing in an inert atmosphere of 200-250 DEG C to form a nano anchoring layer; depositing a main metal film on the surface of the nano anchoring layer, and introducing a rare earth doping element; a pre-reaction layer is constructed through pre-reaction at the low temperature of 400-500 DEG C; and performing high-temperature crystallization at 700-850 DEG C to complete conversion of the main metal film to the crystalline two-dimensional transition metal chalcogenide, and curing the rare earth luminescence center and the structure coating. The method has the advantages that low-damage in-situ integration of the lithium niobate micro-nano structure is realized, rare earth doping is uniform and controllable, and two-dimensional material crystallization is excellent; and a high-performance near-infrared light-emitting heterojunction device can be efficiently prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated photonics and two-dimensional material device manufacturing, and particularly relates to an in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material. BACKGROUND

[0002] The lithium niobate photon platform is considered as the core material for realizing the next generation of multifunctional integrated photon chips due to its excellent electro-optic, acousto-optic and nonlinear optical coefficients. However, the indirect band gap semiconductor characteristics result in extremely low intrinsic light emission efficiency, which is a key bottleneck for building a fully functional lithium niobate photon integrated circuit (PIC). The prior art proposes two solutions: 1. Directly doping rare earth ions (such as Er 3+ ) into the lithium niobate lattice, which can realize light emission, but has problems such as low doping concentration, ion clustering, and increased non-radiative loss leading to passive device performance degradation; 2. Heterogeneous integration of III-V semiconductor lasers through wafer bonding technology, which faces challenges such as complex process, high production cost and difficult thermal management, and is difficult to meet the needs of large-scale integration applications.

[0003] Two-dimensional transition metal chalcogenides (such as MoS2) as emerging direct band gap semiconductor gain media, by introducing rare earth ions (such as Er 3+ ,Yb 3+ ), can realize high-efficiency light emission in the near-infrared communication band, providing a new technical path to solve the lithium niobate light emission bottleneck. However, high-quality integration of such materials onto lithium niobate microcavities faces a fundamental technical contradiction: the high-temperature process (usually ≥850℃) required for traditional two-dimensional material sulfuration far exceeds the thermal budget (usually ≤600℃) of lithium niobate micro-nano structures, which easily leads to irreversible phase change, surface decomposition, microcavity structure cracking and interface adhesion reduction of lithium niobate.

[0004] Specifically, the rare earth doped MoS2 is directly grown on the surface of a lithium niobate (LN) microdisk, which mainly faces two technical obstacles: 1. Thermal sensitivity obstacle: the conventional sulfuration temperature (≥800℃) of Mo to MoS2 will cause phase change, stress cracking and morphology collapse of the LN film / microdisk; in addition, the thermal expansion coefficients of LN and two-dimensional materials do not match, which is particularly prominent during rapid heating, making it difficult to maintain the integrity of the microcavity structure.

[0005] 2. High temperature compatibility and interface bonding difficulty: the conventional epitaxy or transfer integration route of two-dimensional material either exceeds the LN thermal budget due to high process temperature, or affects the device performance due to the introduction of exogenous contamination and residual stress; and the sputtering-sulfuration process for growing rare earth doped MoS2 on the LN substrate directly has problems such as uncontrollable interface chemical reaction, insufficient film adhesion and poor long-term reliability of the device.

[0006] In summary, the prior art restricts the application of high-performance light-emitting devices based on LN microcavities, and therefore there is an urgent need for a stable process that can realize the in-situ, uniform and controllable integration of rare earth doped MoS2 on the LN microdisk. SUMMARY

[0007] To solve the above problems, the present application provides an in-situ integration method of rare earth doped two-dimensional material on the surface of lithium niobate micro-nano structure.

[0008] The first object of the present application is to provide an in-situ integration method of rare earth doped two-dimensional material on the surface of lithium niobate micro-nano structure, comprising the following steps: S1. Pretreating the lithium niobate micro-nano structure substrate; S2. Depositing a sub-nanometer metal layer on the surface of the pretreated substrate by high vacuum magnetron sputtering, the thickness of the sub-nanometer metal layer being less than 1 nm; and annealing at a low temperature in an inert atmosphere at 200-250℃ to form a nano anchoring layer; S3. Depositing a main metal film on the surface of the nano anchoring layer and introducing a rare earth doping element; S4. Constructing a pre-reaction layer by low temperature pre-reaction at 400-500℃; and completing the conversion of the main metal film to a crystalline two-dimensional transition metal chalcogenide and solidifying the rare earth luminescent center and structure coating by high temperature crystallization at 700-850℃.

[0009] Preferably, the process parameters of high vacuum magnetron sputtering in step S2 are as follows: sputtering power 5-10 W, cavity pressure 1-3 mTorr Ar atmosphere, deposition time 5-30 s, and the sub-nanometer metal layer is at the level of sub-monolayer to several atomic layers to realize uniform coverage of the substrate surface.

[0010] Preferably, the inert atmosphere is high-purity Ar or N2, and the annealing time is 5-10 min; the sub-nanometer metal layer is a sub-nanometer Mo layer or a sub-nanometer W layer; and the nano anchoring layer is a molybdate or tungstate transition phase.

[0011] Preferably, the sub-nanometer metal layer is a sub-nanometer Mo layer or a sub-nanometer W layer; the material of the main metal film corresponding to the sub-nanometer metal layer is a Mo film or a W film, and the thickness is 3-30 nm. In step S3, the main metal film is deposited by high vacuum direct current or radio frequency magnetron sputtering, and the process parameters are as follows: sputtering power 20-60 W, Ar flow rate 15-25 sccm, and cavity pressure 1-3 mTorr.

[0012] Preferably, the rare earth doping element includes at least one of Er 3+ , Yb 3+ , Tm 3+ , Eu 3+ , and the doping atom percentage is 0.1-5 at%; the rare earth doping element is introduced by at least one of co-sputtering, step-by-step sputtering or thermal evaporation doping.

[0013] Preferably, when the rare earth doping element is introduced by co-sputtering, the metal target is co-sputtered with a rare earth target or a rare earth oxide target to complete uniform doping of the rare earth element while depositing the main metal film; When the rare earth doping element is introduced by step-by-step sputtering, a rare earth layer or a rare earth oxide layer with a thickness of 0.5-1 nm is sputtered after the main metal film is deposited; When the rare earth doping element is introduced by thermal evaporation doping, a rare earth halide film is deposited on the surface of the main metal film by thermal evaporation process, and the doping of the rare earth element is realized through subsequent sulfidation or selenization.

[0014] Preferably, the low-temperature pre-reaction in step S4 is low-temperature pre-sulfidation or pre-selenization, which is carried out in a mixed gas atmosphere of H2 and Ar with a volume ratio of 1:9, and the holding time is 10-15 min; the pre-reaction layer is amorphous or nanocrystalline MoS x or WS x (x>2) with a loose porous structure; The high-temperature crystallization is treated by a tube furnace in stages or by chemical vapor deposition.

[0015] Preferably, when the high-temperature crystallization is treated by a tube furnace in stages, the tube furnace is raised to 800-850℃ at a temperature rising rate of ≤10℃ / min, and the holding time is 15-30 min; When the high-temperature crystallization is treated by chemical vapor deposition, a sulfur-containing gas or a selenium-containing gas and a rare earth source are introduced at 700-750℃, and the holding time is 15-30 min.

[0016] Preferably, the pretreatment in step S1 includes: first, the substrate is ultrasonically cleaned with deionized water, acetone and anhydrous ethanol in sequence, and the ultrasonic time is 5-10 min each time; after cleaning, the substrate is dried with high-purity nitrogen; the dried substrate is surface-activated by UV-O3 or Ar plasma, the activation power is 50-100 W, and the activation time is 3-10 min; The lithium niobate micro-nano structure substrate is a lithium niobate micro-disk resonant cavity, a micro-ring resonant cavity, a micro-sphere resonant cavity or an optical waveguide structure.

[0017] The second object of the present application is to provide a lithium niobate / rare earth doped two-dimensional transition metal chalcogenide heterojunction light-emitting device, which is prepared by an in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material; the integrated structure is a core-shell or gradient chimeric microstructure, which can generate near-infrared light emission near 1530 nm under 980 nm pumping.

[0018] Compared with the prior art, the present application can achieve the following beneficial effects: (1) Overturning thermal compatibility: through the interface engineering of Mo atomic layer pre-bonding and interface passivation, the lithium niobate microcavity can withstand the high-temperature sulfuration process which is traditionally enough to damage it, and the fundamental obstacle of hetero-integration is solved.

[0019] (2) Excellent interface stability: the interface layer of chemical bonding makes the film adhesion change in quality, the mechanical strength and environmental stability of the device are greatly improved, and the service life is significantly prolonged.

[0020] (3) Excellent light-emitting performance: the unique heterostructure formed by stage temperature control sulfuration, through the double effects of "photonic localization" and "energy sensitization", the light-emitting efficiency and gain of rare earth ions are improved to a new height, which lays a foundation for realizing low threshold laser.

[0021] (4) High process compatibility and universality: the whole process is compatible with the existing micro-nano processing technology and is suitable for wafer-level manufacturing. This technical route can be easily extended to WS2, MoSe2 and other two-dimensional materials and Nd 3+ , Tm 3+ and other rare earth ions to realize wide-spectrum light emission from visible to near-infrared. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a process flow chart of an in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to an embodiment of the present application.

[0023] Figure 2 It is a schematic diagram of a sub-nanometer metal layer pre-bonding and interface passivation process according to an embodiment of the present application; (a) depositing a sub-nanometer Mo atomic layer on the surface of lithium niobate; (b) forming a stable, chemically bonded nano-anchor layer after low-temperature annealing.

[0024] Figure 3 It is a comparison diagram of optical microscopes of lithium niobate micro-disk and a comparative example (without pre-bonding treatment) after sulfuration; in the diagram, the micro-disk structure in area A is complete, and the thin film is uniformly covered, and the lithium niobate thin film in area B of the comparative example is cracked at the edge and the thin film is peeled off.

[0025] Figure 4 Raman spectrum test result provided according to an embodiment of the present application.

[0026] Figure 5 Er-doped MoS2 / LNOI-based lithium niobate micro-disk resonator under 980 nm pumping.

[0027] Reference signs: 1. Substrate; 2. Nano-anchor layer; 3. Main Mo film; 4. MoS2 film. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0029] In order to make the objectives, technical solutions, and advantages of the present application clearer, further detailed descriptions will be given below in combination with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not constitute a limitation on the present application.

[0030] The present application aims to provide a low-damage, controlled, and batchable in-situ integration method of rare earth-doped two-dimensional transition metal chalcogenides and lithium niobate micro-nano structures without damaging the integrity and quality factor (Q factor) of the LN micro-disk structure. The method combines Mo atomic layer pre-bonding passivation and two-stage temperature-controlled sulfuration to construct a rare earth-doped MoS2 light-emitting layer, realizes near-infrared light emission near about 1.53 µm under 980 nm pumping, and significantly reduces the risk of brittle fracture of the LN micro-disk in subsequent high-temperature steps. The method has clear process window and can be extended to other rare earth / two-dimensional materials and other LN microcavity / waveguide structures.

[0031] The present application provides an in-situ integration method of rare earth-doped two-dimensional materials on a lithium niobate micro-nano structure, which specifically comprises the following steps: S1. Lithium niobate micro-nano structure substrate pretreatment; specifically comprising: S11. Select a micro-nano processed LNOI (LN-on-insulator) based lithium niobate micro-nano structure substrate, and sequentially use deionized water, acetone, and anhydrous ethanol to ultrasonically clean the substrate, with each ultrasonic time controlled to be 5-10 min, so as to remove photoresist residues, particulate impurities, and organic contaminants on the surface of the substrate through gradient cleaning; The substrate is specifically a micro-disk resonant cavity, a micro-ring resonant cavity, a micro-sphere resonant cavity or an optical waveguide structure; preferably, the diameter of the micro-disk resonant cavity is 30-120 µm, and the edge thereof is smoothly processed to avoid edge collapse caused by stress concentration in subsequent processes.

[0032] S12. The substrate after cleaning is blown dry with high-purity nitrogen to avoid film growth defects caused by water stain residues.

[0033] S13. The substrate after blowing dry is subjected to surface activation treatment, which removes residual organic groups on the surface of the substrate and introduces active sites such as hydroxyl groups, thereby improving the interfacial wettability and bonding force between the subsequent metal layer and the substrate. Specifically, UV-O3 or Ar plasma activation is used, with an activation power of 50-100 W and an activation time of 3-10 min.

[0034] S2. A sub-nanometer metal layer is deposited and subjected to low-temperature annealing to form a nano-anchor layer; specifically including: S21. The pre-processed lithium niobate micro-nano structure substrate is placed in a high-vacuum magnetron sputtering device, and a sub-nanometer metal layer is deposited by using a direct current (DC) sputtering method. Specifically, the sub-nanometer metal layer is selected from Mo layer or W layer, the sputtering power is controlled to be extremely low, i.e. 5-10 W, the cavity pressure is maintained at 1-3 mTorr in an Ar atmosphere, the deposition time is 5-30 s, the thickness of the deposited metal layer is less than 1 nm, which is at the level of “sub-monolayer to several atomic layers”, and the surface of the substrate is uniformly covered rather than forming a continuous thick film.

[0035] S22. The substrate after deposition of the sub-nanometer metal layer is transferred to an annealing furnace, and subjected to low-temperature annealing treatment in an inert atmosphere (high-purity Ar or N2), with an annealing temperature of 200-250 ℃ and an annealing time of 5-10 min; during the annealing process, the sub-nanometer metal layer and the Nb, O and Li atoms on the surface of the lithium niobate substrate undergo interdiffusion and interface reaction, forming a stable, chemically bonded nano-anchor layer of molybdate or tungstate transition phase; The nano-anchor layer prepared in this step has a triple core function, i.e. stress buffering, chemical bonding and diffusion blocking; specifically, including: (1) heat shielding effect: blocking the direct erosion of sulfur / selenium vapor on the body of lithium niobate in the subsequent high-temperature sulfidation / selenization process; (2) stress buffering effect: relieving the stress generated between lithium niobate and two-dimensional transition metal chalcogenide due to the mismatch of thermal expansion coefficients; (3) nucleation promotion effect: providing high-density, low-energy nucleation sites for the deposition of the subsequent main metal film, and inducing the preferential growth of two-dimensional materials along the (100) crystal plane.

[0036] S3. Main metal film deposition and rare earth doping element introduction; specifically including: S31. In a high vacuum environment, deposit a main metal film on the surface of the nano-anchor layer by direct current (DC) or radio frequency (RF) magnetron sputtering; The main metal film is selected from Mo film or W film corresponding to the sub-nano metal layer, and the total thickness is 3-30 nm; the sputtering process parameters are controlled as follows: power 20-60 W, Ar flow rate 15-25 sccm, and cavity pressure 1-5 mTorr; Preferably, the thickness of the main metal film is 5-15 nm, which can balance the crystalline quality and stress level of the film.

[0037] S32. Introduce rare earth doping elements by any one or combination of the following methods, the rare earth doping elements including at least one of Er 3+ , Yb 3+ , Tm 3+ , Eu 3+ , and the doping atom percentage is controlled to be 0.1-5 at%, preferably 0.2-2 at%, to avoid ion clusters caused by high concentration doping: (1) Co-sputtering: co-target sputtering of a metal target (Mo target or W target) and a rare earth target (such as an Er target) or a rare earth oxide target (such as an Er2O3 target) is performed to uniformly dope the rare earth elements while depositing the main metal film; (2) Step sputtering: after the deposition of the main metal film is completed, a rare earth layer or a rare earth oxide layer with a thickness of 0.5-1 nm is sequentially sputtered, and the rare earth ions can diffuse and solid-solve into the two-dimensional material lattice during the subsequent sulfidation or selenization process; (3) Thermal evaporation doping: as an alternative to sputtering doping, a rare earth halide film is deposited on the surface of the main metal film by thermal evaporation process, and the doping of the rare earth elements is realized during the subsequent sulfidation or selenization process, which can reduce the complexity of the equipment; This step can be in the form of a combination of Er 3+ / Yb 3+ co-doping, which utilizes the high absorption characteristics of Yb 3+ to 980 nm pump light to achieve efficient energy transfer from Yb 3+ to Er 3+ , thereby improving the luminescent efficiency of the rare earth-doped two-dimensional transition metal chalcogenide.

[0038] S4. Stage-wise temperature-controlled sulfidation or selenization treatment: the substrate on which the main metal film is deposited is pre-reacted at low temperature to form a pre-reaction layer, and then the main metal film is converted into a crystalline two-dimensional transition metal chalcogenide at high temperature, and the rare earth luminescent center and the structure are solidified and coated; the controllable growth of the rare earth-doped two-dimensional transition metal chalcogenide is realized, and the thermal damage to the lithium niobate micro-nano structure is avoided; specifically including the following sub-steps: S41. Low-temperature pre-sulphurization or selenization (forming a transition phase pre-reaction layer): the lithium niobate micro-nano structure substrate with deposited main metal film and rare earth doped elements is placed in a tube furnace reaction cavity; first, a mixed protective atmosphere of H2 and Ar is introduced, then the furnace temperature is raised to 400-500°C, and the temperature is maintained for 10-15 min; Specifically, the volume ratio of H2 to Ar is preferably 1:9, and the H2 proportion can be adjusted slightly to control the reaction activity according to the size of the substrate; In this stage, the surface layer of the main metal film (Mo or W film) preferentially reacts with the sulfur source or selenium source to form a non-stoichiometric amorphous or nanocrystalline transition phase metal sulfide or selenide pre-reaction layer (such as MoS x , WS x , where x>2); the pre-reaction layer has a loose porous structure, which can not only serve as a fast channel for the subsequent high-temperature stage of the inward diffusion of the sulfur source or selenium source and the outward migration of the metal source, but also can absorb the interface stress through its own plasticity to avoid cracking of the substrate and the film due to the difference in thermal expansion coefficient.

[0039] S42. High-temperature crystalline sulphurization or selenization (complete crystalline conversion and solidification of rare earth luminescent centers): using a tube furnace for staged processing or chemical vapor deposition, the conversion of the main metal film to a crystalline rare earth doped two-dimensional transition metal chalcogenide is achieved, and the rare earth luminescent centers and structural coating are solidified; specifically as follows: (1) Tube furnace staged processing: after completing the low-temperature pretreatment, the temperature of the tube furnace is raised to 800-850°C at a controllable heating rate of ≤10°C / min (to avoid stress concentration caused by rapid heating), and the temperature is maintained at this temperature for 15-30 min; during this process, the unreacted Mo or W atoms inside are fully reacted with sulfur or selenium through the transition phase pre-reaction layer, completely converted into well-crystallized 2H phase two-dimensional materials (such as MoS2, WS2 or MoSe2), and at the same time, rare earth ions (Er 3+ , Yb 3+ , etc.) are effectively embedded in the two-dimensional material lattice (mainly occupying metal atom sites or existing between layers), achieving the solidification of rare earth luminescent centers and the structural coating of two-dimensional materials; (2) Chemical vapor deposition processing: the substrate with deposited main metal film and rare earth doped elements is placed in a chemical vapor deposition reaction cavity, and at a temperature of 700-750°C, a sulfur-containing gas or selenium-containing gas (such as H2S, Se powder vapor) and a rare earth source (such as a rare earth organic compound vapor) are simultaneously introduced into the reaction cavity, and the temperature is maintained for 15-30 min; during this process, the main metal film reacts with the sulfur source or selenium source to form a two-dimensional transition metal chalcogenide, and at the same time, the rare earth ions provided by the rare earth source are simultaneously doped into the two-dimensional material, completing the sulphurization or selenization, crystalline conversion, and solidification and structural coating of the rare earth luminescent centers in one step; In a specific embodiment, taking the Mo system as an example, the Mo inside is reacted with the MoSx The channel reacts with sulfur fully, and is completely converted into well-crystallized 2H phase MoS2. At the same time, the rare earth ions are effectively introduced into the MoS2 lattice, mainly occupying the Mo sites or existing between the layers. The finally formed film has a unique "core-shell" or "gradient hybrid" microstructure, that is, the inside is high-quality crystalline MoS2, while the surface layer or the grain boundary is wrapped / hybridized with MoS x Phase.

[0040] S43. Furnace cooling and integrated structure forming: after the sulfuration or selenization reaction is completed, the heating device is turned off, and the protective atmosphere is maintained until the furnace temperature naturally cools to room temperature; after cooling, the sample is taken out, and an integrated structure of a rare earth doped two-dimensional transition metal chalcogenide and a lithium niobate micro-nano structure is obtained; The integrated structure includes a lithium niobate micro-nano structure substrate and a rare earth doped two-dimensional transition metal chalcogenide layer covering the surface of the substrate; and has a core-shell or gradient hybrid microstructure in structure: the inside is a high-quality crystalline (2H phase crystalline) rare earth doped two-dimensional material, and the surface layer or the grain boundary is wrapped or hybridized with a transition phase metal sulfide or selenide, which ensures the luminescent performance of the rare earth doped two-dimensional material and improves the interface bonding force of the film and the substrate; at the same time, the lithium niobate micro-nano structure has no crystal phase damage, edge collapse and other defects, and maintains high Q factor optical performance.

[0041] Example 1 This embodiment provides an in-situ integrated method of an Er doped MoS2 / LNOI based lithium niobate microdisk resonant cavity, and a flow chart is shown as Figure 1 shown, and specifically includes the following steps: S1. Select a LNOI based lithium niobate microdisk resonant cavity with a diameter of 80 µm as a substrate 1, and sequentially clean it with deionized water, acetone and anhydrous ethanol for 8 min, dry it by nitrogen blowing, and then activate it by 100W Ar plasma for 5 min; S2. Put the substrate 1 into a high vacuum magnetron sputtering device, deposit a Mo atomic layer by 5W direct current sputtering, the cavity pressure is 2mTorr Ar, the deposition time is 15s, and the thickness is ≤0.5nm; then anneal it at 230°C in a high-purity Ar atmosphere for 8 min, to form a nanometer anchoring layer 2 of a molybdate transition phase; and a principle diagram of the preparation process is shown as Figure 2 shown; S3. Deposit a main Mo film 3 with a thickness of 10nm on the surface of the nanometer anchoring layer 2 by 40W RF magnetron sputtering, the Ar flow is 20sccm, and the cavity pressure is 3mTorr; synchronously co-sputter by an Er2O3 target, and control the Er doping atomic percentage to be 0.8at%; S4: temperature-controlled sulfuration treatment in stages: First stage: Put the sample into the tube furnace, and pass H2 / Ar mixed gas (5 / 45 sccm, volume ratio 1:9) to make the temperature of sulfur source 200℃, and pre-sulfurize at 450℃ for 12 min; Second stage: increase the temperature to 820℃ at a rate of 5℃ / min, and high-temperature sulfurize for 20 min; after cooling down, Er-doped MoS2 film 4 is obtained, and the preparation of Er-doped MoS2 / LNOI-based lithium niobate micro-disk resonator is completed.

[0042] Figure 3 It is an optical microscope photo of the Er-doped MoS2 / LNOI-based lithium niobate micro-disk resonator after sulfurization, in which the left photo is the overall morphology of the micro-disk, and the right photo is a local enlarged view; it can be observed from the photo that the micro-disk surface is completely covered by the uniform film layer without defects such as exposed bottom and holes; the edge of the micro-disk (the junction of regions A and B) maintains a smooth shape without edge collapse, cracks or film layer falling off; the surface of the film layer has no obvious protrusions and wrinkles, and presents a dense and flat appearance. The results prove that, by the sub-nanometer Mo layer anchoring and the stage temperature control sulfurization process, the thermal damage of the lithium niobate micro-disk in the high-temperature process is effectively avoided, and the good combination of the MoS2 film and the substrate is ensured, and the morphology integrity of the micro-nano structure is realized.

[0043] Figure 4 It is the Raman spectrum test result, and it can be seen from the curve in the figure that the characteristic vibration peaks (E - 2g and A1g modes) of 2H phase MoS2 appear near ~400cm 1 , which proves that the main metal film has been successfully converted into crystalline 2H phase MoS2; at the same time, the characteristic peak signal of the lithium niobate substrate in the red curve is covered by the signal of the MoS2 film, which further proves the continuity and uniformity of the film layer; and the slight broadening of the characteristic peak (compared with the standard peak of pure MoS2), combined with the doping parameters in the foregoing, can indicate the lattice micro-strain caused by the Er element after doping. The results show that the sulfurization process of the embodiment realizes the crystalline growth of MoS2 and successfully completes the rare earth doping without damaging the crystal structure of the material.

[0044] The test results are shown in Figure 5 As shown in the figure, a strong PL peak appears near about 1530 nm under 980 nm pumping; there is no crack at the edge of the micro-disk, the microscope photo shows that the film layer is dense, the Raman spectrum is characteristic of 2H MoS2 with slight shift (strain / doping indication).

[0045] It should be understood that the various forms of flow shown above can be used to reorder, add, or remove steps. For example, the steps recited in the present disclosure can be performed in parallel, in series, or in a different order, as long as the desired results of the technical solutions of the present disclosure are achieved, which are not limited herein.

[0046] The above detailed description does not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for in-situ integration of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material, characterized in that: The method comprises the following steps: S1. Pre-treating a lithium niobate micro-nano structure substrate; S2. Depositing a sub-nano metal layer on the surface of the pre-treated substrate by high vacuum magnetron sputtering, and the thickness of the sub-nano metal layer is less than 1 nm; and annealing the sub-nano metal layer at a low temperature in an inert atmosphere at 200-250 ℃ to form a nano anchoring layer; S3. Depositing a main metal film on the surface of the nano anchoring layer and introducing a rare earth doping element; S4. Constructing a pre-reaction layer by low-temperature pre-reaction at 400-500 ℃; Then, high-temperature crystallization at 700-850 ℃ is performed to complete the conversion of the main metal film into a crystalline two-dimensional transition metal chalcogenide and solidify the rare earth luminescent center and structure coating.

2. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 1, characterized in that: The process parameters of the high vacuum magnetron sputtering in step S2 are as follows: sputtering power 5-10 W, cavity pressure 1-3 mTorr Ar atmosphere, deposition time 5-30 s, and the sub-nano metal layer is at a sub-monolayer to several atomic layer level to realize uniform coverage of the substrate surface.

3. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 2, characterized in that: The inert atmosphere is high-purity Ar or N2, and the annealing time is 5-10 min; the sub-nano metal layer is a sub-nano Mo layer or a sub-nano W layer; and the nano anchoring layer is a molybdate or tungstate transition phase.

4. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 1, characterized in that: The sub-nano metal layer is a sub-nano Mo layer or a sub-nano W layer; the material of the main metal film corresponds to the sub-nano metal layer, and the main metal film is a Mo film or a W film with a thickness of 3-30 nm. In step S3, the main metal film is deposited by high vacuum direct current or radio frequency magnetron sputtering, and the process parameters are as follows: sputtering power 20-60 W, Ar flow rate 15-25 sccm, and cavity pressure 1-3 mTorr.

5. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 4, characterized in that: The rare earth doping element includes at least one of Er 3+ , Yb 3+ , Tm 3+ , Eu 3+ , and the doping atom percentage is 0.1-5 at%; the rare earth doping element is introduced by at least one of co-sputtering, step sputtering or thermal evaporation doping.

6. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 5, characterized in that: When the rare earth doping element is introduced by co-sputtering, the metal target and the rare earth target or the rare earth oxide target are co-sputtered to uniformly dope the rare earth element while depositing the main metal film. When the rare earth doping element is introduced by stepwise sputtering, a rare earth layer or a rare earth oxide layer with a thickness of 0.5-1 nm is sputtered after the deposition of the main metal film is completed. When the rare earth doping element is introduced by thermal evaporation doping, a rare earth halide film is deposited on the surface of the main metal film by thermal evaporation process to realize the doping of the rare earth element in the subsequent sulfidation or selenization process.

7. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 1, characterized in that: The low-temperature pre-reaction in the step S4 is low-temperature pre-sulfuration or pre-selenium, which is carried out in a mixed gas atmosphere with a volume ratio of H2 to Ar being 1:9, and the holding time is 10-15 min; and the pre-reaction layer is amorphous or nanocrystalline MoS x or WS x (x>2) with a loose porous structure. The high-temperature crystallization is treated by a tubular furnace in stages or by chemical vapor deposition.

8. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 7, characterized in that: When the high-temperature crystallization is treated by a tubular furnace in stages, the tubular furnace is heated to 800-850 ℃ at a heating rate of ≤10 ℃ / min, and the temperature is maintained for 15-30 min. When the high-temperature crystallization is treated by chemical vapor deposition, a sulfur-containing gas or a selenium-containing gas and a rare earth source are introduced at 700-750 ℃, and the temperature is maintained for 15-30 min.

9. The in-situ integration method of a lithium niobate micro-nano structure surface rare earth doped two-dimensional material according to claim 1, characterized in that: The pre-treatment in step S1 comprises the following steps: first, the substrate is ultrasonically cleaned with deionized water, acetone and anhydrous ethanol in sequence, and the ultrasonic cleaning time is 5-10 min each time; then, the substrate is dried with high-purity nitrogen after cleaning; and then, the dried substrate is surface-activated by UV-O3 or Ar plasma, and the activation power is 50-100 W and the activation time is 3-10 min. The lithium niobate micro-nano structure substrate is a lithium niobate micro-disk resonant cavity, a micro-ring resonant cavity, a micro-sphere resonant cavity or an optical waveguide structure.

10. A lithium niobate / rare earth doped two-dimensional transition metal chalcogenide heterojunction light emitting device, characterized in that: The in-situ integrated method of claim 1 is used to prepare a lithium niobate micro-nano structure surface rare earth doped two-dimensional material; the integrated structure is a core-shell or gradient chimeric microstructure, which can produce near-infrared luminescence near 1530nm under 980nm pumping.

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