WO2022148080A1 - Lead zirconate titanate thin film for next-generation high-speed communication, preparation method therefor, and application thereof - Google Patents

Abstract

A lead zirconate titanate thin film for next-generation high-speed communication in the field of integrated photonics, a preparation method therefor, and an application thereof. The material of a device is based on a lanthanide nitrate seed crystal layer; a lead zirconate titanate precursor solution is prepared by a sol-gel method; a PZT crystal thin film is prepared by spin coating and annealing; and a perovskite type PZT single-phase crystal thin film having a uniform and compact structure and dominant orientation can be obtained. The preparation method is simple in operation, low in energy consumption, and low in costs; the grown thin film is a pure perovskite type single-phase crystal thin film, is high in transparency, and is resistant to high temperature; the thickness and the size of the thin film are easy to adjust; and the requirements of various electro-optical modulation devices can be met. The prepared lead zirconate titanate thin film has a nonlinear effect, an electro-optical effect, a piezoelectric effect, a thermoelectric effect and the like, and can be used for preparing devices such as an optical waveguide, an optical switch, a beam splitter/combiner, a piezoelectric modulator, a thermoelectric modulator, and an electro-optical modulator in an integrated photon loop.

Description

Lead zirconate titanate thin film for next-generation high-speed communication and its preparation method and application technical field

The invention relates to the field of integrated photonic communication, in particular to a lead zirconate titanate film for next-generation high-speed communication, a preparation method and application thereof.

Background technique

Lead zirconate titanate (PZT) is a versatile material with large piezoelectric and electro-optic coefficients, high dielectric constant and significant remanent polarization, showing its applications in piezoelectric, electro-optic and pyroelectric, etc. excellent performance. Therefore, lead zirconate titanate has a wide range of applications in sensors, MEMS, electro-optic modulators, ferroelectric memories and many other fields. However, the preparation of dense and uniform PZT crystal films without cracks, high transparency, and high electro-optic effect has always been a great challenge, especially the preparation of films that can be used in electro-optic modulators has always been a difficulty. The properties of PZT crystalline films are closely related to the composition, texture and phase structure of the films. Therefore, the preparation of high-quality PZT films with large electro-optic effects is of great significance for the electro-optic field.

At present, the preparation methods of PZT films mainly include solid-phase methods: including magnetron sputtering, pulsed laser deposition, molecular beam epitaxy, etc.; liquid-phase methods: hydrothermal method, sol-gel method, etc. The solid-phase method generally uses expensive equipment, difficult to control the atomic ratio, and the film quality is heavily dependent on the target material, and the film size is limited; the hydrothermal method has a cumbersome preparation process and harsh conditions. It is limited in practical application. At present, most PZT thin film seed layers are made of metal platinum and titanium. Due to their absorption of light, their application in the field of electro-optics is severely limited, and it is difficult to prepare lead titanate (PT) as the seed layer, which has an advantageous orientation. The single-phase crystal film is difficult to obtain electro-optic effect.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the invention discloses a lead zirconate titanate film and an electro-optical modulator for next-generation ultra-high-speed communication (in the field of integrated photonics). The material of the device is based on a lanthanide nitrate seed layer, and adopts The lead zirconate titanate precursor solution is prepared by spin coating and annealing crystallization to prepare a dense and uniform perovskite-type single-phase lead zirconate titanate (PZT) thin film. Then, after designing and optimizing the device structure, a series of electro-optical modulation devices are prepared through micro-nano processing techniques such as photolithography and etching.

The purpose of this invention is to realize through the following technical solutions:

A preparation method of a lead zirconate titanate thin film for next-generation high-speed communication, the method comprising the following steps:

(1) Substrate cleaning

cleaning the substrate, removing organic and inorganic impurities on the substrate, and drying; the substrate is an inorganic substrate or a composite substrate formed by growing an inorganic thin film on the inorganic substrate;

(2) Configure the seed layer solution

Dissolving lanthanide nitrate in n-propanol or ether alcohol solvent to prepare lanthanide nitrate solution, which is used as a seed layer solution;

(3) Configure the precursor solution of lead zirconate titanate Pb _x Zr _y Ti _1-y O ₃

First, prepare a lead acetate solution, wherein the solute is lead acetate, and the solvent is an ether alcohol solvent; then, any one of tetraethyl titanate, isopropyl titanate or tetraisobutyl titanate is prepared according to The atomic ratio is dissolved in lead acetate solution, and then zirconium n-propoxide or zirconium isopropoxide solution is added dropwise according to the atomic ratio in the chemical formula, and stirred evenly; finally, acetylacetone is added dropwise as a chelating agent and stirred thoroughly to obtain chelated zirconium. Lead titanate precursor solution, sealed and left to stand;

(4) Preparation of seed layer

The seed layer solution prepared in step (2) is dropped on the cleaned substrate in step (1), and then spin coating and pyrolysis treatment are performed in turn to obtain the seed layer; during the preparation process, the spin coating speed and spin coating are adjusted by adjusting Number of times to adjust the thickness of the film;

(5) Preparation of lead zirconate titanate thin film

The lead zirconate titanate precursor solution prepared in step (3) is dropped on the seed layer prepared in step (4), and spin-coating and annealing are performed in turn to obtain a lead zirconate titanate crystal thin film; during the preparation process, adjusting The spin coating speed and the number of spin coats adjust the thickness of the film.

Further, in the step (2), the prepared lanthanide nitrate solution has a concentration of 0.01-0.4 mol/L;

In the step (3), the prepared PZT precursor solution has a concentration of 0.02-1.0 mol/L.

Further, in the step (4), the temperature of pyrolysis is 200-450°C;

In the step (5), the annealing temperature is 500-850°C.

Further, in the step (3), in the precursor solution of lead zirconate titanate Pb _x Zr _y Ti _1-y O ₃ , x=1.0-1.5, y=0.2-0.8.

Further, in the step (3), the amount of the added chelating agent acetylacetone is 0.5%-8% of the total volume.

Further, in the step (1), the substrate is selected from silicon, aluminum oxide, magnesium oxide, glass, or any of silicon nitride, silicon dioxide, titanium dioxide, and aluminum nitride grown on an inorganic substrate. A composite substrate formed therefrom.

Further, the ether alcohol solvents in the steps (2) and (3) are all selected from any one or more of ethylene glycol methyl ether, diethylene glycol methyl ether, ethylene glycol ethyl ether, and the like.

A lead zirconate titanate thin film prepared by any one of the above preparation methods.

An electro-optical modulator made of a lead zirconate titanate film, a cladding film or a strip waveguide or a Mach-Zehnder structure is prepared on the lead zirconate titanate film by a micro-nano processing process, and a corresponding electrode structure is prepared to obtain a corresponding electro-optical modulator.

Further, the material of the cladding film is SiO ₂ , TiO ₂ or Si ₃ N ₄ , and the material of the strip waveguide and the Mach-Zehnder structure is lead zirconate titanate, SiO ₂ , TiO ₂ , Si ₃ N ₄ , the electrode materials are gold, silver, copper, titanium, aluminum, and nickel.

The beneficial effects of the present invention are as follows:

(1) the preparation method of lead zirconate titanate thin film of the present invention is simple in operation, low in energy consumption and low in cost;

(2) The thin film grown by the method of the present invention is a pure perovskite type single-phase crystal thin film, which has high transparency, high temperature resistance, easy adjustment of thin film thickness and size, and can meet the needs of various electro-optical modulation devices.

(3) The present invention applies the prepared PZT film to an electro-optical modulator, which has good compatibility, an electro-optic coefficient of 68-280 pm/V, and a modulation bandwidth of 10-100 GHz, which has a huge application prospect in the field of integrated photonic communication in the future.

Description of drawings

Fig. 1 is the XRD curve diagram of the seed layer thin film prepared by multiple spin coating in Example 3;

Fig. 2 is the XRD curve diagram of the lead zirconate titanate thin film prepared by multiple spin coating preparations in Example 3;

Fig. 3 is the XRD graph of the lead zirconate titanate thin film prepared in Example 5;

4 is a schematic diagram of the waveguide structure designed for the electro-optic coefficient test in Example 10;

5 is an electron microscope image of the slab waveguide prepared in Example 10;

FIG. 6 is a light emitting test diagram of the slab waveguide prepared in Example 10, and the selected light source is a 1550 nm semiconductor laser.

FIG. 7 is a schematic structural diagram of the SiO ₂ ridge waveguide based on the lead zirconate titanate thin film prepared in Example 11. FIG.

FIG. 8 is a schematic structural diagram of the SiO ₂ ridge waveguide based on the lead zirconate titanate thin film prepared in Example 12. FIG.

FIG. 9 is a light output test diagram of the lead zirconate titanate thin film-based SiO ₂ ridge waveguide prepared in Example 11, and the selected light source is a 1550 nm semiconductor laser.

FIG. 10 is a schematic diagram of the waveguide of the upper and lower electrode structures based on the lead zirconate titanate thin film prepared in Example 13. FIG.

FIG. 11 is a schematic diagram of the waveguide of the upper and lower electrode structures based on the lead zirconate titanate thin film prepared in Example 14. FIG.

FIG. 12 is a schematic structural diagram of the lead zirconate titanate thin film-based ridge waveguide prepared in Example 15. FIG.

13 is a schematic structural diagram of the Mach-Zehnder based lead zirconate titanate film prepared in Example 16

Detailed ways

The present invention will be described in detail below according to the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become clearer.

Example 1

(1) Rinse the glass substrate with deionized water, then use acetone, deionized water, and isopropanol to ultrasonically clean for 10 minutes in turn, and then place it in a drying oven to dry at 85°C for use;

(2) dissolving lanthanum nitrate in n-propanol solution to obtain a solution with a concentration of 0.02mol/L seed layer, which is sealed for use;

(3) According to the atomic ratio of Pb _{1.0 Zr 0.2} Ti _0.8 O _{3 ,} lead acetate trihydrate is dissolved in diethylene glycol methyl ether to obtain lead acetate solution; The atomic ratio of _0.8 O ₃ was added dropwise to the lead acetate solution, and then the zirconium isopropoxide solution was added dropwise according to the atomic ratio of Pb _1.0 Zr _0.2 Ti _0.8 O ₃ , and stirred evenly; finally, 0.5% of the total acetylacetone was added dropwise as a chelating agent , fully stirred to obtain the chelated precursor solution; the concentration is 0.04mol/L, sealed and left to stand for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the glass substrate after the above-mentioned cleaning, successively throw the film at 500rpm and 3500rpm, and then pyrolyze at 200°C for 30min, the heating rate is 10°C/min, and the cooling rate is 5°C/min. min, the thickness is about 2nm;

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), successively pass 500 rpm and 3000 rpm, undergo pyrolysis at 200 °C for 30 min and anneal at 500 °C for 20 min, and the heating rate is 10 °C /min, the cooling rate is 5°C/min, and the perovskite crystal film is obtained with a thickness of about 5nm, and the target thickness can be obtained by repeated spin coating.

Example 2

(1) Soak the sapphire substrate with concentrated sulfuric acid, rinse it with deionized water, then ultrasonically clean it with acetone, deionized water, and isopropanol for 10 minutes in turn, and then place it in a drying oven for drying at 85°C for use;

(2) dissolving neodymium nitrate in ethylene glycol methyl ether solution to obtain a 0.04mol/L neodymium nitrate seed layer solution for use;

(3) according to the atomic ratio of Pb _{1.1 Zr0.65} Ti _0.35 O ₃ , lead acetate trihydrate is dissolved in ethylene glycol methyl ether, lead acetate solution; then isobutyl titanate is pressed Pb _{1.1 Zr0.65} Ti _0.35 The atomic ratio of O ₃ is added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution is added dropwise according to the atomic ratio of Pb _1.1 Zr _0.65 Ti _0.35 O ₃ , and stirring is uniform; the 2% acetylacetone is added dropwise as the final volume ratio. The chelating agent is fully stirred to obtain a chelated PZT precursor solution with a concentration of 0.2 mol/L, sealed and left to stand for use;

(4) drop the above-mentioned neodymium nitrate seed layer solution on the sapphire substrate after the above-mentioned cleaning, successively through 500rpm and 3500rpm film throwing, through 200 ℃ of pyrolysis 30min, the heating rate is 10 ℃/min, the cooling rate is 5 ℃/ min, the thickness is about 4nm;

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), successively pass 500 rpm and 3000 rpm, undergo pyrolysis at 200 °C for 30 min and anneal at 600 °C for 20 min, and the heating rate is 10 °C /min, the cooling rate is 5℃/min, and the perovskite crystal film is obtained, with a thickness of about 25nm, and the target thickness can be obtained by repeated spin coating

Example 3

(1) Rinse the glass substrate with deionized water, then use acetone, deionized water, and isopropanol to ultrasonically clean for 10 minutes in turn, and then place it in a drying oven to dry at 85°C for use;

(2) praseodymium nitrate is dissolved in ethylene glycol methyl ether solution, the obtained concentration is 0.1mol/L seed layer solution, sealed for use;

(3) According to the atomic ratio of Pb _1.2 Zr _0.52 Ti _0.48 O ₃ , lead acetate trihydrate is dissolved in ethylene glycol methyl ether to obtain lead acetate solution; then isopropyl titanate is divided into Pb _1.2 Zr _0.52 Ti _0.48 The atomic ratio of O ₃ was added dropwise to the lead acetate solution, and then the zirconium isopropoxide solution was added dropwise according to the atomic ratio of Pb _1.2 Zr _0.52 Ti _0.48 O ₃ , and stirred evenly; finally, 5% of the total acetylacetone was added dropwise as a chelating agent, Fully stirring to obtain a chelated precursor solution; the concentration is 0.4mol/L, sealed and left to stand for use;

(4) drop the above-mentioned praseodymium nitrate seed layer solution on the glass substrate after the above-mentioned cleaning, successively throw the film at 500 rpm and 3500 rpm, and then pyrolyze at 200 ℃ for 30 min, the heating rate is 10 ℃/min, and the cooling rate is 5 ℃/min min, repeat the above steps three times, the thickness of the seed layer is about 24nm, the XRD curve of this seed layer is shown in Figure 1, indicating that the seed layer is a single-phase crystal structure, which is beneficial as a nucleation site. Crystallization of lead zirconate titanate films;

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), successively pass 500 rpm and 3000 rpm, undergo pyrolysis at 200 °C for 30 min and anneal at 600 °C for 20 min, and the heating rate is 10 °C /min, the cooling rate is 5°C/min, and a perovskite crystal film with a thickness of about 50 nm is obtained. Repeat the above steps 4 times with a thickness of about 200 nm to obtain a perovskite crystal film. The XRD test curve is as follows As shown in FIG. 2, it shows that the lead zirconate titanate thin film prepared by the present invention has a single-phase perovskite crystal structure, and its preferred orientation is (100) direction, and the target thickness can be obtained by increasing the number of spin coating.

Example 4

(1) Rinse the magnesium oxide substrate with ionized water, then use acetone, deionized water, and isopropanol for ultrasonic cleaning for 10 minutes successively, and then place it in a drying oven to dry at 85 ° C, and stand by;

(2) dissolving samarium nitrate hexahydrate in ethylene glycol ether solution, and stirring until it is fully dissolved, the obtained concentration is 0.036mol/L samarium nitrate seed layer solution, which is set aside for use;

(3) according to the atomic ratio _of Pb _1.3 Zr _0.35 Ti _0.65 O _{3 ,} lead acetate trihydrate is dissolved in ethylene glycol ether to obtain lead acetate solution _; The atomic ratio of ₃ is added dropwise to the lead acetate solution, and then the zirconium isopropoxide solution is added dropwise according to the atomic ratio of Pb _1.3 Zr _0.35 Ti _0.65 O ₃ and stirred evenly; finally, 3% acetylacetone is added dropwise as a chelating agent , fully stirred to obtain a chelated lead zirconate titanate precursor solution with a concentration of 1.0 mol/L, sealed and left to stand for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the magnesium oxide substrate after the above-mentioned cleaning, successively through 500rpm and 3500rpm film throwing, through 300 ℃ of pyrolysis for 20 minutes, the heating rate is 10 ℃/min, the cooling rate is 5 °C/min.

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), successively pass 500 rpm and 3000 rpm, undergo pyrolysis at 200 °C for 30 min and anneal at 850 °C for 5 min, and the heating rate is 10 °C /min, the cooling rate is 5°C/min, and a perovskite crystal film with a thickness of about 100 nm is obtained, and the target thickness can be obtained by repeating the above steps.

Example 5

(1) Rinse the sapphire substrate with ionized water, then use acetone, deionized water, and isopropanol for ultrasonic cleaning for 10 minutes in turn, and then place it in a drying oven for drying at 85°C, and set aside for use;

(2) dissolving samarium nitrate hexahydrate in ethylene glycol ether solution, and stirring until it is fully dissolved, the obtained concentration is 0.036mol/L samarium nitrate seed layer solution, which is set aside for use;

( ₃ ) according to the atomic ratio _of Pb _1.5 Zr _0.52 Ti _0.48 O ₃ , dissolve lead acetate _trihydrate in ethylene glycol ether to obtain lead acetate solution _; The atomic ratio of zirconium isopropoxide was added dropwise to the lead acetate solution, and then the zirconium isopropoxide solution was added dropwise according to the atomic ratio of Pb _1.5 Zr _0.52 Ti _0.48 O ₃ , and stirred evenly; finally, acetylacetone with a volume ratio of 3% was added dropwise as a chelating agent, Fully stirring to obtain a chelated lead zirconate titanate precursor solution with a concentration of 0.4 mol/L, sealed and left to stand for use;

(4) drop the above-mentioned samarium nitrate seed layer solution on the sapphire substrate after the above-mentioned cleaning, successively through 500rpm and 3500rpm film throwing, through 450 ℃ of pyrolysis for 5 minutes, the heating rate is 10 ℃/min, the cooling rate is 5 ℃ /min.

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), successively pass 500 rpm and 3000 rpm, undergo pyrolysis at 200 °C for 30 min and anneal at 800 °C for 10 min, and the heating rate is 10 °C /min, the cooling rate is 5°C/min, and a perovskite crystal film with a thickness of about 50 nm is obtained, and the above steps are repeated 3 times with a thickness of about 160 nm. The XRD test curve is shown in Figure 3, the bottom curve is the XRD curve of the blank sapphire substrate of the control group, and the top is the XRD curve of the lead zirconate titanate thin film, indicating that the lead zirconate titanate thin film shown in the present invention can be prepared under these conditions. A perovskite crystal film with a single-phase structure was obtained, and the preferred orientation in the (100) direction was obtained.

Example 6

(1) The silicon wafer substrate is cleaned by the standard RCA method, and then dried in a drying oven at 85°C for use;

(2) dissolving neodymium nitrate hexahydrate in ethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a 0.1mol/L neodymium nitrate seed layer solution for use;

(3) according to the atomic ratio of Pb _1.1 Zr _0.8 Ti _0.2 O ₃ , dissolve lead acetate trihydrate in ethylene glycol methyl ether, lead acetate solution; then dissolving isobutyl titanate according to Pb _1.1 Zr _0.8 Ti _0.2 O ₃ The atomic ratio of zirconium isopropoxide is added dropwise to the lead acetate solution, and then the zirconium isopropoxide solution is added dropwise according to the atomic ratio of Pb _1.1 Zr _0.8 Ti _0.2 O ₃ ; finally, acetylacetone with a volume ratio of 8% is added dropwise as a chelating agent, fully stirred, A chelated lead zirconate titanate precursor solution is obtained, the concentration is 0.4mol/L, sealed and left to stand for use;

(4) drop the above-mentioned neodymium nitrate seed layer solution on the above-mentioned cleaned silicon wafer substrate, then sling film at 500 rpm and 3500 rpm, and then pyrolyze at 350 ℃ for 20 min, the heating rate is 10 ℃/min, and the cooling rate is 5 ℃ /min;

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), successively pass 500 rpm and 3000 rpm, undergo pyrolysis at 200 °C for 30 min and anneal at 650 °C for 15 min, and the heating rate is 10 °C /min, the cooling rate is 5°C/min, a perovskite crystal film is obtained with a thickness of about 50 nm, a perovskite crystal film is obtained, and the target thickness can be obtained by repeating the above steps.

Example 7

(1) Use the standard RCA method (remove the DHF cleaning process) for the silicon/silicon nitride substrate, and then place it in a drying oven for drying at 85°C until it is used;

(2) dissolving lanthanum nitrate in the ethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a lanthanum nitrate seed layer solution with a concentration of 0.036 mol/L, for use;

( ₃ ) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , _dissolve lead acetate in ethylene glycol methyl ether, lead _acetate solution _; Add dropwise to lead acetate solution, then add zirconium n-propoxide solution dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ and stir evenly; finally add 5% acetylacetone by volume as a chelating agent and stir well , obtain the chelated light yellow lead zirconate titanate precursor solution, the concentration is 0.4mol/L, sealed and stand for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the above-mentioned cleaned silicon/silicon nitride substrate, and perform uniform glue at 500 rpm and 3500 rpm successively, and then undergo pyrolysis at 400 ° C. The heating rate is 10 ° C/min, and the cooling rate is 5℃/min;

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), successively pass 500 rpm and 3000 rpm, undergo pyrolysis at 200 °C for 30 min and anneal at 600 °C for 15 min, and the heating rate is 10 °C /min, the cooling rate is 5°C/min, and a perovskite crystal film with a thickness of about 50 nm is obtained, and the target thickness can be obtained by repeating the above steps.

Example 8

(1) Use the standard RCA method (removing the DHF cleaning process) for the silicon/silicon dioxide substrate, and then place it in a drying oven for drying at 85°C until it is used;

(2) dissolving lanthanum nitrate in the ethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a lanthanum nitrate seed layer solution with a concentration of 0.036 mol/L, for use;

(3) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , lead acetate trihydrate is dissolved in ethylene glycol methyl ether to obtain a lead acetate solution; then isopropyl titanate is divided according to Pb _1.15 Zr _0.52 Ti _0.48 O The atomic ratio of ₃ is added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution is added dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ and stirred evenly; finally, 5% acetylacetone is added dropwise as a chelating agent , fully stirred to obtain a chelated, pale yellow lead zirconate titanate precursor solution with a concentration of 0.4mol/L, sealed and left to stand for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the above-mentioned cleaned silicon/silicon dioxide substrate, first at 50 rpm, at 350 rpm for 40 seconds, and then pyrolyzed at 300 ℃, and the heating rate is 10 ℃/min , the cooling rate is 5℃/min;

(5) dropwise adding the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), slinging the film at 500 rpm and 3000 rpm in turn, heating at 240°C for 20min, and finally annealing at 600°C for 10min in a tube furnace, The heating rate is 100°C/min, and the cooling rate is 50°C/min, and the perovskite crystal film is prepared.

Example 9

(1) Rinse the magnesium oxide substrate with deionized water, then use acetone, deionized water, and isopropanol for ultrasonic cleaning for 10 minutes in turn, and then place it in a drying oven for drying at 85 ° C, and stand by;

(2) dissolving samarium nitrate in diethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a solution with a concentration of 0.036mol/L lanthanum nitrate seed layer, for use;

(3) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , lead acetate trihydrate is dissolved in diethylene glycol methyl ether to obtain lead acetate solution; then isopropyl titanate is divided according to Pb _1.15 Zr _0.52 Ti The atomic ratio of _0.48 O ₃ was added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution was added dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , and stirred evenly; finally, 5% acetylacetone was added dropwise as a solution. The chelating agent is fully stirred to obtain a chelated mixed solution; the chelated lead zirconate titanate precursor solution, with a concentration of 0.4 mol/L, is sealed and left to stand for use;

(4) drop the above-mentioned samarium nitrate seed layer solution on the above-mentioned cleaned magnesium oxide substrate, first at 50 rpm, at 350 rpm for 40 seconds, and through 300 ℃ of pyrolysis, the heating rate is 10 ℃/min, the cooling rate is 5℃/min;

(5) dropwise adding the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), slinging the film at 500 rpm and 3000 rpm in turn, heating at 240°C for 20min, and finally annealing at 600°C for 10min in a tube furnace, The heating rate is 100°C/min, and the cooling rate is 50°C/min, and the perovskite crystal film is prepared.

Example 10

(1) place the sapphire substrate in an ultrasonic cleaner using acetone, dilute hydrochloric acid, deionized water, and isopropanol as cleaning fluids for 10 minutes, respectively, and then place it in a drying oven to dry at 85° C. for later use;

(2) dissolving lanthanum nitrate in the ethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a lanthanum nitrate seed layer solution with a concentration of 0.036 mol/L, for use;

(3) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , lead acetate trihydrate is dissolved in ethylene glycol methyl ether to obtain lead acetate solution; then isopropyl titanate is divided according to Pb _1.15 Zr _0.52 Ti _0.48 The atomic ratio of O ₃ was added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution was added dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , and stirred evenly; finally, 5% acetylacetone was added dropwise as a chelate mixture, fully stirred to obtain a chelated, pale yellow lead zirconate titanate precursor solution with a concentration of 0.4mol/L, sealed and left to stand for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the cleaned sapphire substrate, firstly glue at 500 rpm for 5 seconds, then spin the film at 3500 rpm for 40 seconds, heat at 440°C for 5 minutes, and the heating rate is 10°C/min , the cooling rate is 5°C/min, and the above steps are repeated 3 times;

(5) Add dropwise the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), first spin the film at 500 rpm and even 3000 rpm for 40 seconds, heat at 200°C for 5 minutes, and finally anneal at 650°C in a tube furnace For 10 min, the heating rate was 10°C/min, and the cooling rate was 5°C/min, and the above steps were repeated 3 times to obtain a perovskite crystal film with a thickness of about 160 nm.

(6) Spin-coating sol-gel silica on the PZT film, heating at 120 °C for 2 hours, and heating at 150 °C for 2 hours, as the upper cladding layer, to obtain a flat-plate waveguide structure. The thickness of colloidal silica is 1.7um, and the thickness of PZT film is 160nm. FIG. 5 is a schematic diagram of the planar waveguide and electrodes designed by the present invention, the electrodes used are aluminum electrodes, the method used is heating evaporation coating, and the thickness of the aluminum electrodes is about 200 nm. 1550nm and 1310nm semiconductor lasers and infrared cameras were used to conduct optical tests on the above-mentioned slab waveguides. Figure 6 is a test chart of the infrared camera receiving light, and the wavelength is 1550nm. As shown in Figure 6, the lead zirconate titanate film prepared by the present invention has high transparency, The absorption of optical signals in the communication band is small. The aluminum coplanar electrodes were connected by probes, and the light was tested for electro-optic modulation by applying an alternating voltage.

Example 11

(1) Use the standard RCA method (removing the DHF cleaning process) for the silicon/silicon dioxide substrate, and then place it in a drying oven for drying at 85°C until it is used;

(2) lanthanum nitrate is dissolved in ethylene glycol methyl ether solution, stirred until it is fully dissolved, and the obtained concentration is 0.036mol/L lanthanum nitrate seed layer solution, stand-by;

(3) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , lead acetate trihydrate is dissolved in ethylene glycol methyl ether to obtain a lead acetate solution; then isopropyl titanate is divided according to Pb _1.15 Zr _0.52 Ti _0.48 O The atomic ratio of ₃ is added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution is added dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ and stirred evenly; finally, 5% acetylacetone is added dropwise as a chelating agent , fully stirred to obtain a chelated mixed solution; the chelated mixed solution was mixed with lead acetate solution, and stirred until the solution was clear and transparent to obtain a pale yellow lead zirconate titanate precursor solution with a concentration of 0.4 mol/L, Sealed and set aside for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the silicon/silicon dioxide substrate after the above-mentioned cleaning, successively throw the film at 500 rpm and 3500 rpm, heat at 400 ℃ for 10 min, the heating rate is 10 ℃/min, and the cooling rate is 5℃/min;

(5) Add dropwise the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), firstly glue at 500 rpm for 5 seconds, then spin the film at 3000 rpm for 40 seconds, heat at 240°C for 2 minutes, and finally After annealing at 600°C for 10min in a tube furnace, the above steps were repeated three times, the heating rate was 100°C/min, and the cooling rate was 50°C/min to obtain a perovskite crystal film.

(6) The sol-gel silica was spin-coated on the PZT film, heated at 120 °C for 2 h, and heated at 150 °C for 2 h, with a thickness of 300 nm. Then, through standard photolithography process and standard etching process in turn, the SiO ₂ stripe structure as shown in Figure 7 is obtained. Finally, through standard photolithography process again, metal electrodes are prepared to obtain the lead zirconate titanate film as shown in Figure 7. SiO ₂ ridged waveguide structure. 1550nm and 1310nm semiconductor lasers and infrared cameras were used to conduct optical tests on the above-mentioned slab waveguides. Figure 9 is a test chart of the infrared camera receiving light, and the wavelength is 1550nm. As shown in Figure 9, the lead zirconate titanate film prepared by the present invention has high transparency, The absorption of optical signals in the communication band is small. The coplanar electrode is connected by a probe, and the light is modulated by applying an alternating voltage. The measured electro-optic coefficient is greater than 240pm/V.

Example 12

(1) Use the standard RCA method (remove the DHF cleaning process) for the silicon/silicon nitride substrate, and then place it in a drying oven for drying at 85°C until it is used;

(2) dissolving lanthanum nitrate in the ethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a lanthanum nitrate seed layer solution with a concentration of 0.036 mol/L, for use;

(3) according to the atomic ratio of Pb _1.15 Zr _0.3 Ti _0.7 O ₃ , dissolve lead acetate trihydrate in ethylene glycol methyl ether to obtain lead acetate solution; then dissolving isopropyl titanate according to Pb _1.15 Zr _0.3 Ti _0.7 O The atomic ratio of ₃ is added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution is added dropwise according to the atomic ratio of Pb _1.15 Zr _0.3 Ti _0.7 O ₃ and stirred evenly; finally, 5% acetylacetone is added dropwise as a chelating agent. , fully stirred to obtain a chelated mixed solution; the chelated mixed solution was mixed with lead acetate solution, and stirred until the solution was clear and transparent to obtain a pale yellow lead zirconate titanate precursor solution with a concentration of 0.4 mol/L, Sealed and set aside for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the above-mentioned cleaned silicon/silicon nitride substrate, firstly glue at 500 rpm for 5 seconds, then throw the film at 3500 rpm for 40 seconds, and heat at 200° C. for 30 minutes. is 10°C/min, and the cooling rate is 5°C/min;

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), firstly glue at 500 rpm for 5 seconds, then spin the film at 3000 rpm for 40 seconds, heat at 240°C for 20 minutes, and finally After annealing at 600 °C for 10 min in a tube furnace, the above steps were repeated three times, the heating rate was 100 °C/min, and the cooling rate was 50 °C/min to obtain a perovskite crystal film.

(6) Prepare a silicon nitride film with a thickness of 200 nm by PECVD on the PZT film, and then go through a standard photolithography process and a standard etching process in turn to obtain the Si ₃ N ₄ ridge waveguide structure shown in Figure 8, and finally pass the standard again. A photolithography process was used to prepare a metal electrode to obtain a Si ₃ N ₄ ridge waveguide structure based on a lead zirconate titanate film as shown in Figure 8. The coplanar electrode was connected by a probe, and the light was modulated by applying an alternating voltage. Its electro-optic coefficient is greater than 68pm/V.

Example 13

(1) The silicon substrate is cleaned by the standard RCA method, and then dried in a drying oven at 85°C for use;

(2) A layer of metal electrodes is prepared on the silicon wafer cleaned in step (1) with a thickness of about 200 nm, and then SiO ₂ with a thickness of about 2 um is prepared by PECVD as a lower cladding layer.

(3) dissolving lanthanum nitrate in ethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a solution of lanthanum nitrate seed layer with a concentration of 0.036 mol/L, for use;

(4) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , lead acetate trihydrate is dissolved in ethylene glycol methyl ether to obtain lead acetate solution; then isopropyl titanate is divided into Pb _1.15 Zr _0.52 Ti _0.48 O The atomic ratio of ₃ is added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution is added dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ and stirred evenly; finally, 5% acetylacetone is added dropwise as a chelating agent , fully stirred to obtain a chelated lead zirconate titanate precursor solution with a concentration of 0.4mol/L, sealed and left to stand for use;

(5) drop the above-mentioned lanthanum nitrate seed layer solution on the above-mentioned cleaned silicon/silicon dioxide substrate, firstly glue at 500 r/min for 5 seconds, then spin the film at 3500 r/min for 40 seconds, and at 200° C. Volatile organic solvent, anneal at 430°C for 10 minutes in a tube furnace, with a heating rate of 10°C/min and a cooling rate of 5°C/min;

(6) Add dropwise the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), firstly glue at 500 rpm for 5 seconds, then spin the film at 3000 rpm for 40 seconds, heat at 240°C for 20 minutes, and finally After annealing at 600 °C for 10 min in a tube furnace, the above steps were repeated three times, the heating rate was 100 °C/min, and the cooling rate was 50 °C/min to obtain a perovskite crystal film.

(7) The sol-gel silica was spin-coated on the PZT film, heated at 120°C for 2h, and heated at 150°C for 2h, with a thickness of 2um. Then, metal electrodes are prepared to obtain a slab waveguide based on the upper and lower electrode structures of the lead zirconate titanate film as shown in FIG. 10 .

Example 14

(1) The silicon substrate is cleaned by the standard RCA method, and then dried in a drying oven at 85°C for use;

(2) A metal electrode with a thickness of about 200 nm is prepared on the silicon wafer cleaned in step ( ₁ ), and then Si3N4 with a thickness of about _2um is prepared by PECVD as a lower cladding layer.

(3) dissolving lanthanum nitrate in ethylene glycol methyl ether solution, stirring until it is fully dissolved, to obtain a solution of lanthanum nitrate seed layer with a concentration of 0.036 mol/L, for use;

(4) according to the atomic ratio _of Pb _1.3 Zr _0.52 Ti _0.48 O ₃ , dissolve lead acetate trihydrate in ethylene glycol methyl ether, stir until the solution is clear and transparent, to obtain lead acetate solution; The atomic ratio of _0.52 Ti _0.48 O ₃ was added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution was added dropwise according to the atomic ratio of Pb _1.3 Zr _0.52 Ti _0.48 O ₃ , and stirred evenly; finally, 5% acetyl acetate was added dropwise. Acetone is used as a chelating agent and is fully stirred to obtain a chelated lead zirconate titanate precursor solution with a concentration of 0.4 mol/L, which is sealed and left to stand for use;

(5) drop the above-mentioned lanthanum nitrate seed layer solution on the above-mentioned cleaned silicon/silicon dioxide substrate, firstly glue at 500 r/min for 5 seconds, then spin the film at 3500 r/min for 40 seconds, and at 200° C. Volatile organic solvent, anneal at 430°C for 10 minutes in a tube furnace, with a heating rate of 10°C/min and a cooling rate of 5°C/min;

(6) Add dropwise the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), firstly glue at 500 rpm for 5 seconds, then spin the film at 3000 rpm for 40 seconds, heat at 240°C for 20 minutes, and finally After annealing at 600 °C for 10 min in a tube furnace, the above steps were repeated three times, the heating rate was 100 °C/min, and the cooling rate was 50 °C/min, to obtain a perovskite crystal film.

(7) A layer of Si ₃ N ₄ is prepared on the PZT film by PECVD as an upper cladding layer. Then, metal electrodes are prepared to obtain a slab waveguide based on the upper and lower electrode structures of the lead zirconate titanate film as shown in FIG. 11 .

Example 15

(1) Use the standard RCA method (remove the DHF cleaning process) for the silicon/silicon oxide substrate, and then place it in a drying oven for drying at 85°C until it is used;

(2) dissolving lanthanum nitrate in ethylene glycol methyl ether solution to obtain a 0.036mol/L lanthanum nitrate seed layer solution for use;

( ₃ ) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O , dissolve lead acetate trihydrate in ethylene glycol methyl ether, stir until the solution is clear and transparent to obtain lead acetate solution _; The atomic ratio of Zr _0.52 Ti _0.48 O ₃ was added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution was added dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ and stirred evenly; Acetylacetone is used as a chelating agent, and is fully stirred to obtain a chelated lead zirconate titanate precursor solution with a concentration of 0.4 mol/L, which is sealed and left to stand for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the above-mentioned cleaned silicon/silicon dioxide substrate, firstly glue at 500 r/min for 5 seconds, then spin the film at 3500 r/min for 40 seconds, and at 200° C. Volatile organic solvent, anneal at 430°C for 10 minutes in a tube furnace, with a heating rate of 10°C/min and a cooling rate of 5°C/min;

(5) dropwise add the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), firstly glue at 500 rpm for 5 seconds, then spin the film at 3000 rpm for 40 seconds, heat at 240°C for 20 minutes, and finally After annealing at 600 °C for 10 min in a tube furnace, the above steps were repeated three times, the heating rate was 100 °C/min, and the cooling rate was 50 °C/min, to obtain a perovskite crystal film.

(6) The PZT ridge waveguide structure shown in Fig. 11 is obtained through a standard photolithography process and an etching process. After a standard photolithography process, a metal electrode as shown in the figure is prepared, and a zirconium titanate-based structure is obtained as shown in Fig. 12. Lead film ridge waveguide structure.

Example 16

(1) Use the standard RCA method (remove the DHF cleaning process) for the silicon/silicon nitride substrate, and then place it in a drying oven for drying at 85°C until it is used;

(2) dissolving lanthanum nitrate in ethylene glycol methyl ether solution to obtain a 0.036mol/L lanthanum nitrate seed layer solution for use;

(3) according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , dissolve lead acetate trihydrate in ethylene glycol methyl ether, stir until the solution is clear and transparent to obtain lead acetate solution _; The atomic ratio of Zr _0.52 Ti _0.48 O ₃ was added dropwise to the lead acetate solution, and then the n-propoxide zirconium solution was added dropwise according to the atomic ratio of Pb _1.15 Zr _0.52 Ti _0.48 O ₃ , and stirred evenly; Acetylacetone is used as a chelating agent, and is fully stirred to obtain a chelated lead zirconate titanate precursor solution with a concentration of 0.4 mol/L, which is sealed and left to stand for use;

(4) drop the above-mentioned lanthanum nitrate seed layer solution on the above-mentioned cleaned silicon/silicon dioxide substrate, firstly glue at 500 r/min for 5 seconds, then spin the film at 3500 r/min for 40 seconds, and at 200° C. Volatile organic solvent, anneal at 430°C for 10 minutes in a tube furnace, with a heating rate of 10°C/min and a cooling rate of 5°C/min;

(5) Add dropwise the PZT precursor solution prepared in step (3) on the seed layer prepared in step (4), firstly glue at 500 rpm for 5 seconds, then spin the film at 3000 rpm for 40 seconds, heat at 240°C for 20 minutes, and finally After annealing at 600 °C for 10 min in a tube furnace, the above steps were repeated three times, the heating rate was 100 °C/min, and the cooling rate was 50 °C/min, to obtain a perovskite crystal film.

(6) The Mach-Zehnder structure as shown in Figure 13 is obtained through a standard photolithography process and an etching process. After a standard photolithography process, a metal electrode as shown in the figure is prepared, and the result is obtained as shown in Figure 13 Shown is a Mach–Zehnder electro-optic modulator based on a lead zirconate titanate thin film.

Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still The technical solutions described in the foregoing examples are modified, or some technical features thereof are equivalently replaced. All modifications, equivalent replacements, etc. made within the spirit and principle of the invention shall be included within the protection scope of the invention.

Claims (10)

1. A method for preparing a lead zirconate titanate thin film for next-generation high-speed communication, characterized in that the method comprises the following steps:

   (1) Substrate cleaning

   cleaning the substrate, removing organic and inorganic impurities on the substrate, and drying; the substrate is an inorganic substrate or a composite substrate formed by growing an inorganic thin film on the inorganic substrate;

   (2) Configure the seed layer solution

   Dissolving lanthanide nitrate in n-propanol or ether alcohol solvent to prepare lanthanide nitrate solution as the seed layer solution;

   (3) Configure the precursor solution of lead zirconate titanate Pb _x Zr _y Ti _1-y O ₃

   First, prepare a lead acetate solution, wherein the solute is lead acetate, and the solvent is an ether alcohol solvent; then, any one of tetraethyl titanate, isopropyl titanate or tetraisobutyl titanate is prepared according to The atomic ratio is dissolved in lead acetate solution, and then zirconium n-propoxide or zirconium isopropoxide solution is added dropwise according to the atomic ratio in the chemical formula, and stirred evenly; finally, acetylacetone is added dropwise as a chelating agent and fully stirred to obtain chelated zirconium. Lead titanate precursor solution, sealed and allowed to stand.

   (4) Preparation of seed layer

   The seed layer solution prepared in step (2) is dropped on the cleaned substrate in step (1), and then spin coating and pyrolysis treatment are performed in turn to obtain the seed layer; during the preparation process, the spin coating speed and spin coating are adjusted by adjusting Number of times to adjust the thickness of the film;

   (5) Preparation of lead zirconate titanate thin film

   The lead zirconate titanate precursor solution prepared in step (3) is dropped on the seed layer prepared in step (4), and spin-coating and annealing are performed in turn to obtain a lead zirconate titanate crystal thin film; during the preparation process, adjusting The spin coating speed and the number of spin coats adjust the thickness of the film.
2. The method for preparing a lead zirconate titanate thin film for next-generation high-speed communication according to claim 1, wherein in the step (2), the prepared lanthanide nitrate solution has a concentration of 0.01-0.4 mol/ L;

   In the step (3), the concentration of the prepared PZT precursor solution is 0.02-1.0 mol/L.
3. The method for preparing a lead zirconate titanate thin film for next-generation high-speed communication according to claim 1, wherein in the step (4), the pyrolysis temperature is 200-450°C;

   In the step (5), the annealing temperature is 500-850°C.
4. The method for preparing a lead zirconate titanate thin film for next-generation high-speed communication according to claim 1, wherein in the step (3), the lead zirconate titanate Pb _x Zr _y Ti _1-y O ₃ precursor is In the body solution, x=1.0-1.5, y=0.2-0.8.
5. The method for preparing a lead zirconate titanate thin film for next-generation high-speed communication according to claim 1, wherein in the step (3), the amount of the added chelating agent acetylacetone is 0.5%- 8%.
6. The method for preparing a lead zirconate titanate thin film for next-generation high-speed communication according to claim 1, wherein in the step (1), the substrate is selected from silicon, aluminum oxide, magnesium oxide, glass or A composite substrate formed by growing any one of silicon nitride, silicon dioxide, titanium dioxide, and aluminum nitride on an inorganic substrate.
7. The method for preparing a lead zirconate titanate thin film for next-generation high-speed communication according to claim 1, wherein the ether alcohol solvents in the step (2) and the step (3) are all selected from ethylene glycol methyl alcohol Ether, diethylene glycol methyl ether, ethylene glycol ethyl ether, etc. any one or more.
8. A lead zirconate titanate film prepared by the preparation method of any one of the preceding claims.
9. An electro-optical modulator made of the lead zirconate titanate thin film of claim 8, characterized in that a cladding thin film or a strip waveguide or a Mach-Zehnder structure is prepared on the lead zirconate titanate thin film by a micro-nano processing technique, and Corresponding electrode structures are prepared to obtain corresponding electro-optic modulators.
10. The electro-optic modulator according to claim 9, wherein the material of the cladding film is SiO ₂ , TiO ₂ or Si ₃ N ₄ , and the material of the strip waveguide and the Mach-Zehnder structure is Lead zirconate titanate, SiO ₂ , TiO ₂ , Si ₃ N ₄ , the electrode materials are gold, silver, copper, titanium, aluminum, and nickel.

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