CN102180704A - Preparation method of Bi3TiNbO9-Bi4Ti3O12 natural superlattice ferroelectric film on Si substrate - Google Patents

Preparation method of Bi3TiNbO9-Bi4Ti3O12 natural superlattice ferroelectric film on Si substrate Download PDF

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CN102180704A
CN102180704A CN 201110052767 CN201110052767A CN102180704A CN 102180704 A CN102180704 A CN 102180704A CN 201110052767 CN201110052767 CN 201110052767 CN 201110052767 A CN201110052767 A CN 201110052767A CN 102180704 A CN102180704 A CN 102180704A
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王�华
许积文
周尚菊
杨玲
任明放
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Guilin University of Electronic Technology
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Abstract

The invention discloses a preparation method of a Bi3TiNbO9-Bi4Ti3O12 natural superlattice ferroelectric film on an Si substrate. A sol-gel technique is adopted to directly form a natural superlattice structure; in order to overcome the defect that Bi2O3 is volatile at high temperature, a composition formula of moderately excessive Bi is adopted on the basis of the nominal composition of the Bi3TiNbO9-Bi4Ti3O12; multiple spin coating and layer-by-layer annealing are adopted; and film-forming annealing is carried out in an oxygen atmosphere. The method is simple and can satisfy the requirements for the silicon planar technique; and the prepared Bi3TiNbO9-Bi4Ti3O12 ferroelectric film has a superlattice structure, and has the advantages of outstanding ferroelectric properties, excellent antifatigue characteristic and favorable comprehensive properties.

Description

A kind of Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The preparation method of nature superlattice ferroelectric membranc
Technical field:
The invention belongs to informational function thin-film material field, particularly a kind of Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The preparation method of nature superlattice ferroelectric membranc.
Background technology:
Ferroelectric crystal belongs to a subtribe of dielectric crystal, piezoquartz and pyroelectric crystal, so ferroelectric crystal must have dielectric, piezoelectricity and electrical property of heat releasing except that ferroelectricity, the ferroelectrics of light transmission also has electrooptical property.Because special dielectric, electric light, acousto-optic, the light of ferroelectrics sells off, nonlinear optics, pyroelectricity and piezoelectric property, is a kind of material that has commercial application prospect, therefore ferroelectric application has caused the attention of community of physicists and material educational circles very early.Since the seventies, because to going deep into of ferroelectrics understanding, the expansion of artificial ferroelectric material kind, the progress of microelectronics, ferroelectric membranc is the preparation method constantly make progress, the operating voltage of ferroelectric membranc device can reach 3-5V, can with Si or GaAs integrated technique compatibility, thereby for producing at a high speed, the high-density nonvolatile ferroelectric memory, pyroelectric infrared detector, electro-optical modulation device, ferro-electric devices such as image intensifer have been opened up new approach, in microtronics, photoelectronics, field such as integrated optics and microelectromechanical systems demonstrates very application prospects.Bi 4Ti 3O 12Ferroelectric membranc has and very approaching lattice parameter of Si substrate and ferroelectric properties preferably, and particularly anti-fatigue performance is good, is one of preferred material of New Si integrated ferroelectric memory device, sensitive detection parts preparation.At present, this technical field has become one of focus of novel material research in the world.Some research groups of external Motorola, Siemens company, Japan and Korea S and domestic Sichuan University, Fudan University, Tsing-Hua University, Shanghai Silicate Inst., Chinese Academy of Sciences etc. have all obtained some impressive progresses, but the ferroelectric properties of Bi laminated perovskite structure film, particularly the requirement of residual polarization performance and operational device is compared, and also has big gap.
Superstructure causes lattice distortion, thereby influences the performance of material by two or more alternately reorganization of different crystal structure with close lattice parameter.Therefore can make full use of the polarization that this phenomenon strengthens ferroelectric material, keep improving dielectric characteristics on the good fatigue characteristic basis, improving ferroelectric properties thereby be implemented in.The realization of superstructure film has high requirement to technology of preparing.At first, to replace repeated growth and go out which floor, tens layers, even more multi-layered thickness only is the high quality monocrystalline film of several nanometers, tens nanometers; Secondly, ferroelectric superlattice is made up of oxide compound mostly, so manufacturing technology is subjected to very big restriction.At present, the technology that is used to make ferroelectric superlattice mainly contains molecular beam epitaxy (MBE), pulsed laser deposition methods such as (PLD).As the Bi that adopted the PLD prepared of professor M.Okuyama of Japan leader's research group 3TiNbO 9-Bi 4Ti 3O 12(Appl.Phys.Lett.2003,83:1411) and Bi 2MoO 6-Bi 3TiNbO 9(Integrated Ferroelectrics, 2006,79:15) wait Bi 4Ti 3O 12The natural superlattice ferroelectric membranc of base; Minority mechanisms such as domestic Nanjing University have tentatively carried out the research of artificial ferroelectric superlattice, as PLD method LiNbO 3/ Al 2O 3The preparation of ferroelectric/dielectric super-lattice acoustic and acoustic effect (Yang Bin. the research of the crystal of ferroelectric membranc multilayer film superlattice and polarization orientation control and physical influence thereof. the doctorate paper. Nanjing University, 2001.), BaTiO 3/ SrTiO 3(Cui Shufan, in literature, Xu Ming waits .BaTiO for preparation and photoelectric characteristic thereof 3/ SrTiO 3Superlattice interface structure and the research of photoelectric properties relation, artificial lens journal, 2000,29 (5): 261) etc.But these method apparatus expensive, complex process, cost is very high.Up to the present, Shang Weijian adopts sol-gel technology to prepare the report of Bi laminated perovskite nature superlattice ferroelectric membranc.
Summary of the invention
The objective of the invention is to for overcoming the deficiencies in the prior art, and a kind of Si substrate Bi is provided 3TiNbO 9-Bi 4Ti 3O 12The preparation method of nature superlattice ferroelectric membranc, this method is simple and can satisfy the requirement of silicon planner technology, the Bi of its preparation 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc has superstructure and outstanding ferroelectric properties, excellent fatigue resistance and good comprehensive performances.
The technical scheme that realizes goal of the invention is: 1) adopt sol-gel technology, directly form the nature superstructure; 2) for remedying Bi 2O 3At high temperature be easy to volatilization, at Bi 3TiNbO 9-Bi 4Ti 3O 12On the basis of nominal composition batching, adopt the excessive component prescription of Bi appropriateness; 3) adopt repeatedly even glue, layering annealing; 4) film forming annealing is carried out under oxygen atmosphere.
Realize the concrete technology of technique scheme, comprise the steps:
(1) selects for use resistivity＜10 Ω cm, (100) crystal orientation p type single crystalline Si substrate as substrate, and carry out surface treatment and cleaning according to the semiconductor planar processing requirement;
(2) preparation Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol;
(3) colloidal sol for preparing is dripped on the substrate, spare glue again, make wet film;
(4) wet film of even good glue is dried processing, removes carbon, hydrogen composition in the wet film;
(5) will dry the film of handling and carry out anneal;
(6) repeat above-mentioned steps (3)-(5), determine multiplicity, until the film that obtains desired thickness according to the thickness of required film;
(7) to above-mentioned Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Film carries out anneal, forms Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Nature superlattice ferroelectric membranc.
The described preparation of step (2) Bi 3TiNbO 9-Bi 4Ti 3O 12The raw material of colloidal sol is: Bismuth trinitrate, and the ethanol niobium, metatitanic acid fourth fat, ethylene glycol monomethyl ether, Glacial acetic acid, methyl ethyl diketone, its consumption proportion is: (a) Bismuth trinitrate (Bi (NO 3) 35H 2O): ethanol niobium (Nb (OC 2H 5) 5): metatitanic acid fourth fat (C 16H 36O 4Ti) mol ratio is 7.21-7.35: 1.00: 4.00; (b) solvent ethylene glycol methyl ether (C 3H 8O 2): catalyzer Glacial acetic acid (CH 3COOH): stablizer methyl ethyl diketone (CH 3COCH 2COCH 3) volume percent be respectively 30-60%: 10-20%: 20-50%; (c) 6.10-6.17 mole (a) solute raw material (wherein containing: Bismuth trinitrate 3.60-3.67 mole, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat) is joined 93.20ml (b) solvent, catalyzer, stablizer raw material (wherein containing: solvent ethylene glycol methyl ether 30.00-60.00ml, catalyzer Glacial acetic acid 10.00-20.00ml, stablizer methyl ethyl diketone 20.00-50.00ml).Its preparation method comprises the steps:
(1) load weighted Bismuth trinitrate is put into container;
(2) add ethylene glycol monomethyl ether and Glacial acetic acid;
(3) use magnetic stirrer, make it reaction evenly fully, till Bismuth trinitrate dissolves fully;
(4) add the ethanol niobium by the metering ratio;
(5) use magnetic stirrer, up to ethanol niobium dissolving thorough mixing;
(6) measured metatitanic acid fourth fat is put into another container;
(7) add an amount of methyl ethyl diketone, make its sufficient reacting, no longer change up to solution colour;
(8) use magnetic stirrer, make it reaction evenly fully;
(9) solution in above-mentioned two containers is mixed and adds remaining methyl ethyl diketone;
(10) use magnetic stirrer, make it reaction evenly fully, up to the dissolving thorough mixing;
(11) filter, obtain Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol.
The best proportioning of described raw material is: (a) Bismuth trinitrate (Bi (NO 3) 35H 2O): ethanol niobium (Nb (OC 2H 5) 5): metatitanic acid fourth fat (C 16H 36O 4Ti) mol ratio is 7.28: 1.00: 4.00; (b) solvent ethylene glycol methyl ether (C 3H 8O 2): catalyzer Glacial acetic acid (CH 3COOH): stablizer methyl ethyl diketone (CH 3COCH 2COCH 3) volume percent be 45.00%: 18%: 30.20%; (c) 6.14 moles of (a) solute raw materials (wherein containing: 3.64 moles of Bismuth trinitrates, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat) are joined 93.20ml (b) solvent, catalyzer, stablizer raw material (wherein containing: solvent ethylene glycol methyl ether 45.00ml, catalyzer Glacial acetic acid 18.00ml, stablizer methyl ethyl diketone 32.20ml).
The described anneal of step (5): annealing temperature is 600-700 ℃, during annealing oxygen flow be the 1.5-3.0 liter/minute, annealing time is 5-8 minute.
The described anneal of step (7): annealing temperature is 600-700 ℃, during annealing oxygen flow be the 1.5-3.0 liter/minute, annealing time is 30-40 minute.
The present invention directly adopts Sol-Gel prepared Bi on the monocrystalline silicon substrate of (100) crystal orientation 3TiNbO 9-Bi 4Ti 3O 12Nature superlattice ferroelectric membranc, after tested, this ferroelectric membranc has superstructure and outstanding ferroelectric properties, excellent fatigue resistance and good comprehensive performances.
Advantage of the present invention is: (1) adopts sol-gel preparation technology, directly form the nature superstructure, cost is low, because the hydrolysis in the sol-gel technology, polymerization etc. are reflected at carries out in the solution, can realize intermolecular abundant blending, help forming the nature superstructure, each component can be on molecular level uniform mixing, the component control of making film is accurately, and be easy to adjust (doping) component, microcell component uniformity height is easy to big area system film, and cost is low; (2) adopt repeatedly even glue, layering annealed process program can improve degree of crystallinity, reduces the film internal stress; (3) ferroelectric membranc of the present invention's preparation has superstructure and outstanding ferroelectric properties, excellent fatigue resistance and good comprehensive performances.
Description of drawings
Fig. 1 is Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Nature superlattice ferroelectric membranc Sol-Gel preparation technology schematic flow sheet;
Fig. 2 is the Bi of the present invention's preparation 3TiNbO 9-Bi 4Ti 3O 12Nature superlattice ferroelectric membranc is for the brilliant sectional view of the sample of test usefulness;
The Bi of Fig. 3 for preparing on the Si substrate 3TiNbO 9-Bi 4Ti 3O 12X-ray diffraction (XRD) collection of illustrative plates of nature superlattice ferroelectric membranc;
Fig. 4 is Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Transmission electron microscope (TEM) picture of nature superlattice ferroelectric membranc;
Fig. 5 is Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Surface topography scanning electronic microscope (SEM) picture of nature superlattice ferroelectric membranc;
Fig. 6 is Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The ferroelectric hysteresis loop of nature superlattice ferroelectric membranc;
Fig. 7 is Bi 3TiNbO 9-Bi 4Ti 3O 12The fatigue characteristic curve of nature superlattice ferroelectric membranc;
Fig. 8 is Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Capacitance-voltage (C-V) rational curve of nature superlattice ferroelectric membranc.
Embodiment
The invention will be further described below in conjunction with embodiment, but be not the qualification to content of the present invention.
Consider Bi 2O 3Be easy to volatilization at high temperature, therefore at Bi 3TiNbO 9-Bi 4Ti 3O 12On the basis of nominal composition batching, adopt the component prescription of the excessive 3-5% of Bi, to remedy the volatilization loss of Bi.Bi 3TiNbO 9-Bi 4Ti 3O 12Sol formulation is: (a) Bismuth trinitrate (Bi (NO 3) 35H 2O), ethanol niobium (Nb (OC 2H 5) 5), metatitanic acid fourth fat (C 16H 36O 4Ti) mol ratio is 7.21-7.35: 1.00: 4.00; (b) solvent ethylene glycol methyl ether (C 3H 8O 2), catalyzer Glacial acetic acid (CH 3COOH) and stablizer methyl ethyl diketone (CH 3COCH 2COCH 3) volume percent be respectively 30-60%: 10-20%: 20-50%; (c) 6.10-6.17 mole (a) solute raw material (wherein containing: Bismuth trinitrate 3.60-3.67 mole, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat) is joined 93.20ml (b) solvent, catalyzer, stablizer raw material (wherein containing: solvent ethylene glycol methyl ether 30.00-60.00ml, catalyzer Glacial acetic acid 10.00-20.00ml, stablizer methyl ethyl diketone 20.00-50.00ml).
Embodiment 1
(1) selects for use resistivity 3 Ω cm, (100) crystal orientation p type single crystalline Si substrate as substrate, and carry out surface treatment and cleaning according to the semiconductor planar processing requirement;
(2) adopt following raw material (its purity is analytical pure 99.99%) preparation Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol:
Wherein: (a) Bismuth trinitrate (Bi (NO 3) 35H 2O), ethanol niobium (Nb (OC 2H 5) 5), metatitanic acid fourth fat (C 16H 36O 4Ti) mol ratio is 7.35: 1.00: 4.00; (b) solvent ethylene glycol methyl ether (C 3H 8O 2), catalyzer Glacial acetic acid (CH 3COOH) and stablizer methyl ethyl diketone (CH 3COCH 2COCH 3) volume percent be respectively 35.00%: 12.00%: 46.20%; (c) 6.17 moles of (a) solute raw materials (wherein containing: 3.67 moles of Bismuth trinitrates, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat) are joined 93.20ml (b) solvent, catalyzer, stablizer raw material (wherein containing: solvent ethylene glycol methyl ether 35.00ml, catalyzer Glacial acetic acid 12.00ml, stablizer methyl ethyl diketone 46.20ml).
The described Bi of step (2) 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol adopts following steps to make:
1. load weighted Bismuth trinitrate is put into container;
2. add ethylene glycol monomethyl ether and Glacial acetic acid;
3. use magnetic stirrer, make it reaction evenly fully, till Bismuth trinitrate dissolves fully;
4. add the ethanol niobium by the metering ratio;
5. use magnetic stirrer, up to ethanol niobium dissolving thorough mixing;
6. measured metatitanic acid fourth fat is put into another container;
7. add an amount of methyl ethyl diketone, make its sufficient reacting, no longer change up to solution colour;
8. use magnetic stirrer, make it reaction evenly fully;
9. the solution in above-mentioned two containers is mixed and adds remaining methyl ethyl diketone;
10. use magnetic stirrer, make it reaction evenly fully, up to the dissolving thorough mixing;
Filter, obtain Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol;
(3) with the Bi for preparing 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol drips 1-2 with dropper and drips on the substrate, starts sol evenning machine and spares glue, forms wet film;
(4) will spare good wet film and on 250 ℃ constant temperature heat dish, dry processing, remove C, H composition in the wet film;
(5) will dry the film of handling puts into quartz tube furnace and carries out taking out after the anneal.Annealing is carried out under oxygen atmosphere, and annealing temperature is 600 ℃, and oxygen during annealing (analytical pure 99.9%) flow is 2 liters/minute, and the annealing time of step (5) is 5 minutes;
(6) repeat above-mentioned steps (3)-(5) three times, can obtain the Bi that thickness is about 300nm 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc;
(7) anneal in oxygen atmosphere at last, annealing temperature is 600 ℃, and oxygen during annealing (analytical pure 99.9%) flow is 2 liters/minute, and annealing time is 40 minutes, forms required Bi 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc.
For sample is carried out electric performance test, need prepare top electrode (being the Pt electrode) at prepared ferroelectric membranc sample surfaces.The preparation of electrode adopts magnetically controlled DC sputtering technology to carry out.Cover above the ferroelectric membranc with homemade mask during preparation, have the aperture that a lot of diameters are 0.5mm on the mask, utilize magnetron sputtering to obtain required electrode on the ferroelectric membranc surface.The about 70W of sputtering power, base vacuum are 3 * 10 -3Pa, sputter is 1 minute under the Ar atmosphere 20Pa pressure, the about 50nm of thickness of electrode.Full electrode (being the Pt electrode) at the bottom of the Si substrate back is by the same prepared of top electrode then.Above-mentioned preparation technology as shown in Figure 1, the sectional view of the specimen of its preparation is as shown in Figure 2.
Each material purity of embodiment 2:(all requires to be analytical pure more than 99.99%)
(1) uses resistivity 5 Ω cm, (100) crystal orientation p type single crystalline Si substrate as substrate, and carry out surface treatment and cleaning according to the semiconductor planar processing requirement;
(2) adopt following raw material (its purity is analytical pure 99.99%) preparation Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol:
Wherein: (a) Bismuth trinitrate (Bi (NO 3) 35H 2O), ethanol niobium (Nb (OC 2H 5) 5), metatitanic acid fourth fat (C 16H 36O 4Ti) mol ratio is 7.28: 1.00: 4.00; (b) solvent ethylene glycol methyl ether (C 3H 8O 2), catalyzer Glacial acetic acid (CH 3COOH) and stablizer methyl ethyl diketone (CH 3COCH 2COCH 3) volume percent be respectively 45.00%: 18.00%: 30.20%; (c) 6.14 moles of (a) solute raw materials (wherein containing: 3.64 moles of Bismuth trinitrates, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat) are joined 93.20ml (b) solvent, catalyzer, stablizer raw material (wherein containing: solvent ethylene glycol methyl ether 45.00ml, catalyzer Glacial acetic acid 18.00ml, stablizer methyl ethyl diketone 30.20ml).
(3) with the Bi for preparing 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol drips 1-2 with dropper and drips on the substrate, starts sol evenning machine and spares glue, forms wet film;
(4) will spare good wet film and on 250 ℃ constant temperature heat dish, dry processing, remove C, H composition in the wet film;
(5) will dry the film of handling puts into quartz tube furnace and carries out taking out after the anneal.Annealing is carried out under oxygen atmosphere, and annealing temperature is 650 ℃, and oxygen during annealing (analytical pure 99.9%) flow is 2 liters/minute, and the annealing time of step (5) is 5 minutes;
(6) repeat above-mentioned steps (3)-(5) four times, can obtain the Bi that thickness is about 400nm 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc;
(7) anneal in oxygen atmosphere at last, annealing temperature is 650 ℃, and oxygen during annealing (analytical pure 99.9%) flow is 2 liters/minute, and annealing time is 35 minutes, forms required Bi 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc.
All the other are with embodiment 1.
Each material purity of embodiment 3:(all requires to be analytical pure more than 99.99%)
(1) resistivity 10 Ω cm, (100) crystal orientation p type single crystalline Si substrate be as substrate, and carry out surface treatment and cleaning according to the semiconductor planar processing requirement;
(2) adopt following raw material (its purity is analytical pure 99.99%) preparation Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol:
Wherein: (a) Bismuth trinitrate (Bi (NO 3) 35H 2O), ethanol niobium (Nb (OC 2H 5) 5), metatitanic acid fourth fat (C 16H 36O 4Ti) mol ratio is 7.21: 1.00: 4.00; (b) solvent ethylene glycol methyl ether (C 3H 8O 2), catalyzer Glacial acetic acid (CH 3COOH) and stablizer methyl ethyl diketone (CH 3COCH 2COCH 3) volume percent be respectively 55.00%: 18.00%: 20.20%; (c) 6.10 moles of (a) solute raw materials (wherein containing: 3.60 moles of Bismuth trinitrates, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat) are joined 93.20ml (b) solvent, catalyzer, stablizer raw material (wherein containing: solvent ethylene glycol methyl ether 55.00ml, catalyzer Glacial acetic acid 18.00ml, stablizer methyl ethyl diketone 20.20ml);
(3) with the Bi for preparing 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol drips 1-2 with dropper and drips on the substrate, starts sol evenning machine and spares glue, forms wet film;
(4) will spare good wet film and on 250 ℃ constant temperature heat dish, dry processing, remove C, H composition in the wet film;
(5) will dry the film of handling puts into quartz tube furnace and carries out taking out after the anneal.Annealing is carried out under oxygen atmosphere, and annealing temperature is 700 ℃, and oxygen during annealing (analytical pure 99.9%) flow is 2 liters/minute, and the annealing time of step (5) is 5 minutes;
(6) repeat above-mentioned steps (3)-(5) five times, can obtain the Bi that thickness is about 500nm 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc;
(7) anneal in oxygen atmosphere at last, annealing temperature is 700 ℃, and oxygen during annealing (analytical pure 99.9%) flow is 2 liters/minute, and annealing time is 30 minutes, forms required Bi 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc.
All the other are with embodiment 1.
In the above-described embodiments, step (1) can move to step (2) and carries out afterwards.
To described Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The performance test of nature superlattice ferroelectric membranc is as follows:
1.Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12X-ray diffraction (XRD) atlas analysis of nature superlattice ferroelectric membranc:
With X-ray diffraction to Si substrate Bi of the present invention 3TiNbO 9-Bi 4Ti 3O 12The phase structure of nature superlattice ferroelectric membranc sample is analyzed.Figure 3 shows that a typical Bi 3TiNbO 9-Bi 4Ti 3O 12The XRD figure spectrum of nature superlattice film sample.By the figure finding, the one, Bi only appears among the figure 3TiNbO 9-Bi 4Ti 3O 12The diffraction peak of superstructure phase is not observed pure Bi 4Ti 3O 12And Bi 3TiNbO 9The diffraction peak of phase, and be about 2.90nm according to the lattice parameter that correlation data calculation obtains, just in time be Bi 4Ti 3O 12And Bi 3TiNbO 9The mean value of lattice parameter illustrates that the structure of film that this processing method obtains is 1-1Bi really 3TiNbO 9-Bi 4Ti 3O 12Superlattice, and do not form Bi 4Ti 3O 12And Bi 3TiNbO 9Single-phase, the 2nd, substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The growth orientation of nature superlattice ferroelectric membranc there is no tangible influence, and film presents the polycrystalline natural orientation, and each main diffraction peak all occurs, shows that the film crystallization is good.
2.Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The transmission electron microscope (TEM) of nature superlattice ferroelectric membranc is analyzed:
The present invention mainly adopts transmission electron microscope (TEM) to prepared Bi 3TiNbO 9-Bi 4Ti 3O 12The superstructure of ferroelectric membranc sample is observed.Figure 4 shows that a typical Bi 3TiNbO 9-Bi 4Ti 3O 12The TEM picture of nature superlattice film sample.Can find out Bi intuitively by figure 4Ti 3O 12And Bi 3TiNbO 9Structure alternately repeats to make up, and shows that prepared film is the Bi of 1-1 structure really 3TiNbO 9-Bi 4Ti 3O 12Superlattice film.
3.Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The scanning electronic microscope (SEM) of nature superlattice ferroelectric membranc surface topography is analyzed:
The present invention mainly adopts scanning electronic microscope (SEM) to prepared Bi 3TiNbO 9-Bi 4Ti 3O 12The surface topography of ferroelectric membranc sample is observed.Fig. 5 is Bi 3TiNbO 9-Bi 4Ti 3O 12The SEM surface topography picture of a typical sample of nature superlattice ferroelectric membranc.Can see Bi 3TiNbO 9-Bi 4Ti 3O 12Crystal grain is clear and legible, is irregular strip, and size is even, and film surface is smooth, flawless.Prepared Bi is described 3TiNbO 9-Bi 4Ti 3O 12Nature superlattice ferroelectric membranc even compact, quality is good.
4.Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The ferroelectric hysteresis loop of nature superlattice ferroelectric membranc:
Adopt the special-purpose ferroelectric tester RT66A of import to Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The ferroelectric hysteresis loop of nature superlattice ferroelectric membranc is tested, as shown in Figure 6.To sample given among the figure, its film thickness is 400nm, and its residual polarization is about 18.9 μ C/cm 2, coercive electric field is about 132kV/cm.Though the coercive electric field test value is slightly higher, consider the dividing potential drop effect of space charge layer among the Si, actually drop to voltage on the ferroelectric membranc well below impressed voltage, therefore actual coercive electric field should be far below test value.This is Bi up to now 3TiNbO 9-Bi 4Ti 3O 12Ferroelectric membranc adopts the best result of MFS (Metal-Ferroelectric-Semiconductor) structured testing.
5.Bi 3TiNbO 9-Bi 4Ti 3O 12The fatigue characteristic of nature superlattice ferroelectric membranc:
With RT66A to being deposited on Pt/SiO 2Bi on the/p-Si substrate 3TiNbO 9-Bi 4Ti 3O 12The fatigue characteristic of nature superlattice ferroelectric membranc are tested, and promptly specimen is Pt/Bi 3TiNbO 9-Bi 4Ti 3O 12/ Pt capacitance structure, test signal pulses width are 8.6 * 10 -6Second, frequency is 10 5Hz, signal voltage are 10V.Sample is through 10 7-10 11The changing conditions of test polarizability after the inferior polarization reversal, as shown in Figure 7.As seen from the figure, film is through 10 9After the polarization reversal, fatigue substantially appears, even experienced 10 11After the inferior counter-rotating, the slippage of residual polarization does not surpass 10%, illustrates that prepared film has very excellent fatigue resistance.
6.Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Capacitance-voltage (C-V) characteristic of nature superlattice ferroelectric membranc:
Sample thin film surface adopt the magnetically controlled sputter method deposit diameter be the Pt top electrode of 0.5mm, promptly specimen is Pt/Bi 3TiNbO 9-Bi 4Ti 3O 12/ p-Si/Pt capacitance structure is that the Pt electrode is a positive voltage when connecing positive source with top electrode in the test.The ac small signal amplitude is 100mV during test, and direct-current biasing is incremented to+4V from-4V, is decremented to-4V from+4V then, and the alternation amplitude is 0.1V.Test result as shown in Figure 8.At first, as seen from the figure, the stagnant direction of returning of curve is clockwise, the about 0.85V of memory window.Clockwise time stagnant direction of p-Si substrate film C-V curve shows: Bi 3TiNbO 9-Bi 4Ti 3O 12The polarization of nature superlattice ferroelectric membranc has controlled the surface potential of p-Si, and information storage can cause that semiconductor surface charges compensates by the ferroelectric membranc polarization and realize that the width of its memory window has characterized the size of ferroelectric membranc residual polarization.Secondly, curve return stagnate present asymmetric: it is bigger to return the window that stagnates when adding forward bias, and the negative bias electric field window that stagnates next time is less, and curve is offset to the bias voltage negative direction.This is actually Bi 3TiNbO 9-Bi 4Ti 3O 12Under positive and negative bias field, the polarize reflection of asymmetry of film.

Claims (7)

1. Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12The preparation method of nature superlattice ferroelectric membranc, it is characterized in that: this method comprises the steps:
(1) selects for use resistivity＜10 Ω cm, (100) crystal orientation p type single crystalline Si substrate as substrate, and carry out surface treatment and cleaning;
(2) preparation Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol;
(3) colloidal sol for preparing is dripped on the substrate, spare glue again, make wet film;
(4) wet film of even good glue is dried processing, removes carbon, hydrogen composition in the wet film;
(5) will dry the film of handling and carry out anneal;
(6) repeat above-mentioned steps (3)-(5), determine multiplicity, until the film that obtains desired thickness according to the thickness of required film;
(7) to above-mentioned Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Film carries out anneal, forms Si substrate Bi 3TiNbO 9-Bi 4Ti 3O 12Nature superlattice ferroelectric membranc.
2. preparation method according to claim 1 is characterized in that: the described Bi of step (2) 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol is formed by following preparation of raw material, and each raw material and amount ratio are: (a) Bismuth trinitrate: the ethanol niobium: the mol ratio of metatitanic acid fourth fat is 7.21-7.35: 1.00: 4.00; (b) solvent ethylene glycol methyl ether: catalyzer Glacial acetic acid: the volume percent of stablizer methyl ethyl diketone is 30-60%: 10-20%: 20-50%; (c) 6.10-6.17 mole (a) solute raw material is joined 93.20ml (b) solvent, catalyzer, stablizer raw material, contains in wherein said 6.10-6.17 mole (a) the solute raw material: Bismuth trinitrate 3.60-3.67 mole, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat; Contain in described 93.20ml (b) solvent, catalyzer, the stablizer raw material: solvent ethylene glycol methyl ether 30.00-60.OOml, catalyzer Glacial acetic acid 10.00-20.OOml, stablizer methyl ethyl diketone 20.00-50.OOml.
3. preparation method according to claim 1 is characterized in that: the described Bi of step (2) 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol is formed by following preparation of raw material, and each raw material and amount ratio are: (a) Bismuth trinitrate: the ethanol niobium: the mol ratio of metatitanic acid fourth fat is 7.28: 1.00: 4.00; (b) solvent ethylene glycol methyl ether: catalyzer Glacial acetic acid: the volume percent of stablizer methyl ethyl diketone is 45.00%: 18%: 30.20%; (c) 6.14 moles of (a) solute raw materials are joined 93.20ml (b) solvent, catalyzer, stablizer raw material, contain in wherein said 6.14 moles of (a) solute raw materials: 3.64 moles of Bismuth trinitrates, 0.50 mole of ethanol niobium, 2.00 moles in metatitanic acid fourth fat; Contain in described 93.20ml (b) solvent, catalyzer, the stablizer raw material: solvent ethylene glycol methyl ether 45.OOml, catalyzer Glacial acetic acid 18.OOml, stablizer methyl ethyl diketone 32.20ml.
4. according to claim 1 or 2 or 3 described preparation methods, it is characterized in that: described Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol is made by the method that comprises the steps:
(1) load weighted Bismuth trinitrate is put into container;
(2) add ethylene glycol monomethyl ether and Glacial acetic acid;
(3) use magnetic stirrer, make it reaction evenly fully, till Bismuth trinitrate dissolves fully;
(4) add the ethanol niobium by the metering ratio;
(5) use magnetic stirrer, up to ethanol niobium dissolving thorough mixing;
(6) measured metatitanic acid fourth fat is put into another container;
(7) add an amount of methyl ethyl diketone, make its sufficient reacting, no longer change up to solution colour;
(8) use magnetic stirrer, make it reaction evenly fully;
(9) solution in above-mentioned two containers is mixed and adds remaining methyl ethyl diketone;
(10) use magnetic stirrer, make it reaction evenly fully, up to the dissolving thorough mixing;
(11) filter, obtain Bi 3TiNbO 9-Bi 4Ti 3O 12Colloidal sol.
5. preparation method according to claim 1 is characterized in that: the annealing temperature of the described anneal of step (5) is 600-700 ℃, during annealing oxygen flow be the 1.5-3.0 liter/minute, annealing time is 5-8 minute.
6. preparation method according to claim 1 is characterized in that: the annealing temperature of the described anneal of step (7) is 600-700 ℃, during annealing oxygen flow be the 1.5-3.0 liter/minute, annealing time is 30-40 minute.
7. use the Si substrate Bi of each described preparation method's preparation of claim 1-6 3TiNbO 9-Bi 4Ti 3O 12Nature superlattice ferroelectric membranc.
CN 201110052767 2011-03-04 2011-03-04 Preparation method of Bi3TiNbO9-Bi4Ti3O12 natural superlattice ferroelectric film on Si substrate Pending CN102180704A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102255045A (en) * 2011-09-20 2011-11-23 桂林电子科技大学 MgxZn1-xO electrically induced resistance change film and preparation method of asymmetrical structure heterojunction thereof
CN107021649A (en) * 2017-04-18 2017-08-08 陕西科技大学 A kind of LaSrMnCo is co-doped with bismuth ferrite superlattice film and preparation method thereof
CN107140849A (en) * 2017-04-18 2017-09-08 陕西科技大学 A kind of LaSrMnCo/GdSrMnCo is co-doped with bismuth ferrite superlattice film and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
《电工材料》 20100228 李健 等 退火温度对Bi 4Ti 3O12- Bi3TiNbO9 复合薄膜铁电性能的影响 第29页 1-7 , 第2期 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102255045A (en) * 2011-09-20 2011-11-23 桂林电子科技大学 MgxZn1-xO electrically induced resistance change film and preparation method of asymmetrical structure heterojunction thereof
CN107021649A (en) * 2017-04-18 2017-08-08 陕西科技大学 A kind of LaSrMnCo is co-doped with bismuth ferrite superlattice film and preparation method thereof
CN107140849A (en) * 2017-04-18 2017-09-08 陕西科技大学 A kind of LaSrMnCo/GdSrMnCo is co-doped with bismuth ferrite superlattice film and preparation method thereof
CN107021649B (en) * 2017-04-18 2019-06-07 陕西科技大学 A kind of LaSrMnCo is co-doped with bismuth ferrite superlattice film and preparation method thereof
CN107140849B (en) * 2017-04-18 2019-10-11 陕西科技大学 A kind of LaSrMnCo/GdSrMnCo is co-doped with bismuth ferrite superlattice film and preparation method thereof

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