阅读说明：本技术 一种LaMnO3调控Bi4Ti3O12带隙的过渡金属氧化物铁电薄膜及其制备方法 (A kind of LaMnO3Regulate and control Bi4Ti3O12Transition metal oxide ferroelectric thin film of band gap and preparation method thereof ) 是由 曹先胜 吉高峰 于 2019-09-17 设计创作，主要内容包括：本发明属于铁电薄膜技术领域,具体涉及一种LaMnO_3调控Bi_4Ti_3O_(12)带隙的过渡金属氧化物铁电薄膜及其制备方法,以LaMnO_3插入Bi_4Ti_3O_(12)的过渡金属氧化物铁电陶磁为靶材,以(001)面SrTiO_3为衬底,通过脉冲激光分子束外延技术沉积Bi_4Ti_3O_(12)-LaMnO_3薄膜。本发明制备LaMnO_3插入Bi_4Ti_3O_(12)过渡金属氧化物基多铁薄膜的方法,整个过程都在同一腔体内进行从而保证了样品的纯度,采用常规设备,非常利于推广。制得的复合材料薄膜表现为强铁电性,在深紫外区具有较高的透射率,可以透过较高能量的光子,为过渡金属氧化物基多铁新型器件提供理论与技术基础,具有广阔的应用前景。(The invention belongs to ferroelectric thin-film technology fields, and in particular to a kind of LaMnO 3 Regulate and control Bi 4 Ti 3 O 12 Transition metal oxide ferroelectric thin film of band gap and preparation method thereof, with LaMnO 3 It is inserted into Bi 4 Ti 3 O 12 Transition metal oxide ferroelectricity pottery magnetic be target, with (001) face SrTiO 3 For substrate, Bi is deposited by Pulsed laser molecular beam epitaxy technology 4 Ti 3 O 12 ‑LaMnO 3 Film.The present invention prepares LaMnO 3 It is inserted into Bi 4 Ti 3 O 12 The method of transition metal oxide Quito iron thin film, whole process carries out ensure that all in same cavity the purity of sample, very conducive to promotion using conventional equipment.Composite material film obtained shows as strong ferroelectricity, in dark purple outskirt transmissivity with higher, can penetrate the photon of higher-energy, provide theoretical and technical foundation for transition metal oxide Quito iron new device, have broad application prospects.)

1. a kind of LaMnO₃Regulate and control Bi₄Ti₃O₁₂The preparation method of the transition metal oxide ferroelectric thin film of band gap, which is characterized in that The preparation method is that: first by Bi₂O₃Powder, MnO₂Powder, La₂O₃Powder and Ti₂O₃Powder ground and mixed is uniform, calcined, Base, sintering, obtains LaMnO₃It is inserted into Bi₄Ti₃O₁₂Then transition metal oxide ferroelectric ceramics target passes through pulse laser point Beamlet epitaxy is in (001) face SrTiO₃LaMnO is deposited on substrate₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric polarons Material after annealing, obtains ferroelectric thin film.

2. LaMnO according to claim 1₃Regulate and control Bi₄Ti₃O₁₂The preparation of the transition metal oxide ferroelectric thin film of band gap Method, which is characterized in that steps are as follows for the preparation method:

(1) molecular formula Bi is pressed₄Ti₃O₁₂-LaMnO₃In stoichiometric ratio weigh the pure powder Bi of analysis₂O₃Powder, MnO₂Powder, La₂O₃Powder and Ti₂O₃Powder, ball milling mixing is uniform, then 800-900 DEG C calcining 2-3 hours, obtain Bi₄Ti₃O₁₂- LaMnO₃Ceramic powder；

(2) it by ceramic powder compression moulding, is burnt 2-3 hours at the beginning of 750 DEG C -900 DEG C, crushes and blank material is made in secondary compression moulding, Blank material forms LaMnO in 950-1100 DEG C of sintering₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric ceramics target；

(3) using Pulsed laser molecular beam epitaxy method in (001) face SrTiO₃LaMnO is deposited on substrate₃It is inserted into Bi₄Ti₃O₁₂Transition Metal oxide ferroelectric ceramics target, obtains ferroelectric thin film after annealing.

3. LaMnO according to claim 1₃Regulate and control Bi₄Ti₃O₁₂The preparation of the transition metal oxide ferroelectric thin film of band gap Method, which is characterized in that step (3) the deposition LaMnO₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric ceramics target, warp The step of ferroelectric thin film is obtained after annealing is as follows:

(1) with (001) face SrTiO₃For substrate, substrate is successively dipped into acetone, ethyl alcohol, each ultrasound 10min in deionized water, It is rinsed again with deionized water after taking-up, finally with dry N₂Drying, for use；

(2) by LaMnO₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric ceramics target is placed in laser molecular beam epitaxy system Target platform position；By step (1) treated SrTiO₃Substrate is fixed on sample and drags, and puts vacuum chamber into；

(3) cavity is vacuumized, heats substrate, it is raw by Pulsed laser molecular beam epitaxy method on (001) face of STO substrate Long LaMnO₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric thin film；

(4) by Bi₄Ti₃O₁₂-LaMnO₃Ferroelectric thin film carries out in-situ annealing, obtains Bi₄Ti₃O₁₂-LaMnO₃Ferroelectric thin film.

4. LaMnO according to claim 3₃Regulate and control Bi₄Ti₃O₁₂The preparation of the transition metal oxide ferroelectric thin film of band gap Method, which is characterized in that step (2) described LaMnO₃It is inserted into Bi₄Ti₃O₁₂Ceramic target is set as 5cm at a distance from substrate.

5. LaMnO according to claim 3₃Regulate and control Bi₄Ti₃O₁₂The preparation of the transition metal oxide ferroelectric thin film of band gap Method, which is characterized in that step (3) the rear chamber pressure that is evacuated is 2 × 10^-6Pa, the heating temperature of substrate are 730 DEG C, laser energy 5J/cm², the pulse frequency of laser is 10Hz.

6. a kind of LaMnO of any one of -5 the method preparations according to claim 1₃Regulate and control Bi₄Ti₃O₁₂The transition metal of band gap Oxide ferroelectric film, which is characterized in that the film includes: that surface is titanium dioxide TiO₂Monocrystalline (001) strontium titanates SrTiO₃Substrate, and it is deposited on substrate the LaMnO to be formed₃Regulate and control Bi₄Ti₃O₁₂The transition metal oxide ferroelectric thin of band gap Film, the ferroelectric thin film has controllable photovoltaic property, with a thickness of 40nm.

Technical field

The invention belongs to ferroelectric thin-film technology fields, and in particular to a kind of LaMnO₃Regulate and control Bi₄Ti₃O₁₂The transition gold of band gap Belong to oxide ferroelectric film and preparation method thereof.

Background technique

Band gap (E_g) regulation be present material research and photoelectric device application core.By regulating and controlling the band gap of semiconductor, The heterojunction structure preparation that band gap customization can be achieved, such as two-dimensional electron gas and tunnel structure.These researchs are to quantrm electrodynamics The understanding of physical mechanism provides foundation, and then promotes the appearance of more relevant devices.In addition, adjusting E_gAbility for opening Hair high performance solar batteries and transparent conductive oxide become more and more important.Such as by replacing traditional III-V with In or Al Semiconductor GaAs (E_g=1.42eV) in Ga, its Eg can continuously be turned down to 0.35eV or up to 2.12eV, it is this simple Alloying can lead to band gap spectrum greater than 1eV.On the other hand, the breakthrough of nearest composite oxides is provided us to semiconductor Understanding be dissolved into the chance in the unusual physical property of transition metal oxide.For example, it was discovered that in several composite oxides Quantum Transport behavior expression goes out significantly improving for oxide mass, causes to be considered as the distinctive property of semiconductor.However, although Huge effort has been paid, but has not yet realized a large amount of and controllable band gap adjustment in transition metal oxide.In order to adjust Cross the E of metal oxide_g, it may be considered that other elements modifications or substitutions transition metal is used, because the inherent characteristic of band gap is main Derived from the strong locality feature of d electronics.However, the excellent physical properties of the transition metal oxide as caused by d- electronics are with band The change of gap and disappear.These difficulties, which hinder, grinds more effective transparent conductive oxide and low band gaps photovoltaic oxide Study carefully.Especially ferroelectric oxide causes new concern due to intrinsic inherent potential that its spontaneous polarization generates.

Summary of the invention

The purpose of the present invention is to provide one kind to have strong ferroelectricity, broad-band gap, LaMnO can be achieved₃Regulate and control Bi₄Ti₃O₁₂Band The preparation method of the transition metal oxide ferroelectric thin film of gap and ferroelectric thin film prepared therefrom.To research and develop based on regulation band gap Transition metal oxide ferroelectricity new device provides theoretical and technical foundation.

The present invention is with LaMnO₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric ceramics is target, is with (001) face STO Substrate deposits Bi by Laser Molecular Beam Epitaxy₄Ti₃O₁₂-LaMnO₃Film, that is, first by Bi₂O₃Powder, MnO₂Powder, La₂O₃Powder and Ti₂O₃Powder ground and mixed is uniform, is calcined, embryo processed, and sintering obtains LaMnO₃It is inserted into Bi₄Ti₃O₁₂Transition gold Belong to oxide ferroelectric ceramic target, then by Pulsed laser molecular beam epitaxy method in (001) face SrTiO₃It is deposited on substrate LaMnO₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric ceramics target, after annealing, obtains ferroelectric thin film.Preparation method is specific Steps are as follows:

(1) molecular formula Bi is pressed₄Ti₃O₁₂-LaMnO₃In stoichiometric ratio weigh the pure powder raw material of analysis, weigh Bi₂O₃Powder Body, MnO₂Powder, La₂O₃Powder and Ti₂O₃Powder, after ball milling mixing is uniform 800-900 DEG C calcining 2-3 hours, obtain Bi₄Ti₃O₁₂-LaMnO₃Ceramic powder.

(2) it by above-mentioned ceramic powder compression moulding, is burnt 2-3 hours at the beginning of 750 DEG C -900 DEG C, crush and secondary is pressed into shape At blank material, blank material is in 2-5 hours formation LaMnO of 950-1100 DEG C of sintering₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric ceramics Target.

On the one hand the calcining of lower temperature can make raw material carry out pre-reaction, so that composition is more uniform.Another aspect energy So that densifying between ceramic particle, the shrinking percentage of follow-up sintering is reduced.

(3) using (001) face STO as substrate, substrate is successively soaked in acetone, ethyl alcohol, each ultrasound in deionized water 10min is rinsed with deionized water again after taking-up, finally with dry N₂Drying, for use；

(4) LaMnO for obtaining step (1)₃It is inserted into Bi₄Ti₃O₁₂Transition metal oxide ferroelectric ceramics target is placed in sharp The target platform position of optical molecule beam epitaxy system, by step (2), treated that STO substrate is fixed on sample carrier, puts vacuum chamber into；

Wherein, Bi₄Ti₃O₁₂-LaMnO₃Target is set as (4~6cm) at a distance from substrate, and vacuumizing rear chamber pressure is 2 ×10^-6Pa；

(5) cavity is vacuumized, heats substrate, on STO substrate (001) face, by Pulsed laser molecular beam epitaxy method, Grow Bi₄Ti₃O₁₂-LaMnO₃Film, until Bi₄Ti₃O₁₂-LaMnO₃Film thickness is about 40nm；

The heating temperature of substrate is 730 DEG C, laser energy 5J/cm², laser pulse frequency is 10Hz to prevent Bi from waving Hair.

(6) finally by Bi₄Ti₃O₁₂-LaMnO₃Film carries out in-situ annealing, obtains positioning substitution Bi₄Ti₃O₁₂-LaMnO₃It closes Gold thin film；

Annealing temperature is 730 DEG C, annealing time 30min.

The LaMnO of preparation₃Regulate and control Bi₄Ti₃O₁₂The transition metal oxide ferroelectric thin film of band gap includes: that surface is titanium dioxide Titanium TiO₂Monocrystalline (001) strontium titanates SrTiO₃Substrate, and be deposited on substrate the LaMnO to be formed₃Regulate and control Bi₄Ti₃O₁₂Band The transition metal oxide ferroelectric thin film of gap, the ferroelectric thin film has controllable photovoltaic property, with a thickness of 40nm.

The beneficial effects of the present invention are: this preparation provided by the invention while there is strong ferroelectricity, broad-band gap Bi₄Ti₃O₁₂-LaMnO₃The method of transition metal oxide ferroelectric thin film, whole process all carry out ensure that sample in a cavity The purity of product is very beneficial for promoting using conventional equipment.

Using pulse laser, the power density of laser can be increased, increase the energy that target composition sputters out, from forming Film quality is more preferable, is conducive to thin film densification and the binding force with substrate.Using high-energy density pulse laser, avoid The volatilization bring loss of Bi, is conducive to the content for keeping Bi element in film in sputtering process.

Bi₄Ti₃O₁₂-LaMnO₃System, which is used as, has low E_gOne of ferroelectric member.Itself and conventional transition metal oxide Difference passes through LaMnO₃Insertion, changes the E of system_g, while Bi is kept again₄Ti₃O₁₂Strong ferroelectricity.Because of E_gDetermine material Most of electronics and optical characteristics, therefore adjust E_gAbility for develop have urgent characteristic transition metal oxide provide Unprecedented approach.

Detailed description of the invention

Fig. 1 is Bi of the invention₄Ti₃O₁₂-LaMnO₃Transition metal oxide ferroelectric thin film XRD diagram.

Fig. 2 is Bi of the invention₄Ti₃O₁₂-LaMnO₃Transition metal oxide Electrode of Ferroelectric Films intensity map.

Fig. 3 is Bi of the invention₄Ti₃O₁₂-LaMnO₃Transition metal oxide ferroelectric thin film photovoltaic current graph.

Fig. 4 is Bi of the invention₄Ti₃O₁₂-LaMnO₃Transition metal oxide ferroelectric thin film transmittance figure.

Fig. 5 is to be not inserted into LaMnO₃When pure Bi₄Ti₃O₁₂Electrode of Ferroelectric Films intensity map.

Fig. 6 is to be not inserted into LaMnO₃When pure Bi₄Ti₃O₁₂Ferroelectric thin film photovoltaic current graph.

Fig. 7 is to be not inserted into LaMnO₃When pure Bi₄Ti₃O₁₂Ferroelectric thin film transmittance figure.

Specific embodiment

The present invention is further illustrated below in conjunction with example.