Perovskite type ferroelectric nitride thin film material and preparation method and application thereof

Abstract

The invention provides a perovskite type ferroelectric nitride thin film material and a preparation method and application thereof. Specifically, the invention provides a perovskite type ferroelectric nitride thin film material which is a single crystal and has the following chemical formula: CeTaN3. The invention also provides a method for preparing the perovskite type ferroelectric nitride thin film material, which comprises the following steps of: (1) growing an amorphous CeTaN3 thin film on the surface of a substrate by adopting a laser pulse deposition technology; and (2) annealing the amorphous CeTaN3 thin film in an ammonia gas atmosphere so as to form the single crystal CeTaN3 thin film. The invention further provides application of the perovskite type ferroelectric nitride thin film material provided by the invention or the perovskite type ferroelectric nitride thin film material prepared by the method provided by the invention in a transistor or a nonvolatile memristor device. The single crystal perovskite type ferroelectric nitride thin film material can stably exist at room temperature, has excellent crystal quality and remarkable ferroelectricity, and is simple in preparation method.

Description

Technical Field

[0001] The present invention belongs to the field of materials and specifically relates to a perovskite-type ferroelectric nitride thin film material and a preparation method and application thereof. Background Art

[0002] The silicon-based technology integration commonly used in the semiconductor industry has always been the focus of ferroelectric thin film material research. Silicon-based technology itself has advantages such as high mobility and adjustable carrier concentration. Combined with the reversible polarization characteristics of ferroelectric thin films, it can give electronic devices the potential to surpass traditional silicon-based devices. In addition, ferroelectric thin film materials can greatly reduce the cost of exploring new integration processes by being compatible with existing CMOS processes, and are also conducive to accelerating the development of new devices and technologies. At present, the high dielectric constant and non-volatile polarization characteristics of ferroelectric materials have shown unique advantages in important devices such as high-performance field effect transistors, ferroelectric tunnel junctions, and non-volatile memories.

[0003] At present, silicon-based integration of ferroelectric functions mainly relies on perovskite-type ternary oxides and binary oxides. 3 、BiFeO 3 and PbTiO 3 Perovskite-type ternary oxides and their superlattice systems have been extensively studied. Although these perovskite-type ternary oxides have outstanding ferroelectric properties and are compatible with silicon-based technology to a certain extent, the thin film epitaxial conditions used to prepare these perovskite-type ternary oxides are generally more stringent, and they also face the problems of high cost and difficulty in ensuring device performance. Therefore, these perovskite-type ternary oxides have not yet been widely used in silicon-based semiconductor technology. HfO 2 Binary oxides such as quartz have excellent dielectric and ferroelectric properties, but their crystal orientation control and device durability still need to be improved.

[0004] The nitride system is also a large material family with rich physical properties. It has important applications in biomedicine, energy and environment, mechanical processing and electronic devices. In particular, transition metal nitrides, in addition to excellent mechanical properties, also have many novel physical properties such as ferroelectricity, ferromagnetism and superconductivity. Binary nitride AlN and its Sc-doped system Al 1-x Sc x N has attracted extensive attention in recent years. It is highly compatible with existing CMOS technology and can achieve high dielectric constant and high ferroelectric polarization value by adjusting the Sc doping concentration. 1-x Sc x The quality of N film is highly dependent on Sc doping technology, and how to ensure uniformity and defect control are issues that still need to be resolved.

[0005] Perovskite-type ternary nitrides containing transition metals have been reported to have strong spin-orbit coupling and strong electron correlation effects, and are predicted to have rich physical properties, including ternary nitride materials with non-centrosymmetric structures. 3 Since the valence of the N anion is -3, the valence of the A and B ions must satisfy A 4+ and B 5+ (or A 3+ and B 6+ ) can satisfy the valence conservation. In addition, perovskite-type ternary nitride ABN 3 Energy stability is required, so the perovskite-type ternary nitride ABN can exist stably. 3 Very rare. Even perovskite ternary nitride ABN 3 It can exist stably, but it is difficult to ensure its accurate chemical composition and high-quality crystallization. Due to the difficulty of synthesis, perovskite-type ternary nitride ABN 3 Development has been slow over the past few decades.

[0006] Therefore, there is an urgent need for a new single-crystalline perovskite-type ternary nitride material that can exist stably at room temperature, has excellent crystal quality, has significant ferroelectricity and is simple to prepare. Summary of the invention

[0007] The object of the present invention is to provide a new single crystal perovskite type ferroelectric nitride thin film material, which can exist stably at room temperature, has excellent crystal quality and has significant ferroelectricity.

[0008] Another object of the present invention is to provide a method for preparing the perovskite ferroelectric nitride thin film material of the present invention. The method is simple and greatly reduces the difficulty of preparing the perovskite ferroelectric nitride thin film material.

[0009] The above-mentioned object of the present invention is achieved through the following technical solutions.

[0010] In a first aspect, the present invention provides a perovskite-type ferroelectric nitride thin film material, which is a single crystal and has the following chemical formula: CeTaN 3 .

[0011] The inventors of the present application unexpectedly discovered that when the polycrystalline target material CeTaN 3 The method of the present invention is used to prepare single crystal CeTaN 3 When a thin film material is prepared, a thin film material can be obtained which can be stable at room temperature, has excellent crystal quality and has significant ferroelectricity.

[0012] Preferably, in the perovskite ferroelectric nitride thin film material of the present invention, the lattice constant of the perovskite ferroelectric nitride thin film material is The space group is P4mm.

[0013] Preferably, in the perovskite-type ferroelectric nitride thin film material described in the present invention, the indirect band gap of the perovskite-type ferroelectric nitride thin film material is 1.06 eV.

[0014] Preferably, in the perovskite ferroelectric nitride thin film material of the present invention, the ferroelectric polarization value of the perovskite ferroelectric nitride thin film material is 15-30 μC / cm 2 The single crystal perovskite type ferroelectric nitride thin film material of the present invention has the characteristic of breaking spatial inversion symmetry.

[0015] Preferably, in the perovskite-type ferroelectric nitride thin film material described in the present invention, the orientation of the perovskite-type ferroelectric nitride thin film material is (001) orientation or (011) orientation.

[0016] In a second aspect, the present invention provides a method for preparing the perovskite-type ferroelectric nitride thin film material of the present invention, which comprises the following steps:

[0017] (1) Using laser pulse deposition technology to grow amorphous CeTaN on the substrate surface 3 film;

[0018] (2) Make the amorphous CeTaN 3 The film was annealed in an ammonia atmosphere to form single-crystalline CeTaN 3 film.

[0019] Preferably, the method of the present invention further comprises the following step before step (1): cleaning the surface of the substrate.

[0020] Preferably, in the method described in the present invention, the substrate is LaAlO 3 (001), SrTiO 3 (001), LSAT((LaAlO 3 ) 0.3 -(Sr 2 AlTaO 6 ) 0.7 )(001), SrTiO 3 (011), Si(001), SiC(0001) or GaN(0001).

[0021] In some embodiments of the present invention, if the substrate is Si (001), the oxide layer on the Si surface is etched away by hydrofluoric acid.

[0022] Preferably, in the method described in the present invention, the substrate is LaAlO 3 (001), SrTiO 3 (001) or LSAT((LaAlO 3 ) 0.3 -(Sr 2 AlTaO 6 ) 0.7 )(001), the single crystal CeTaN 3 The film is oriented (001). According to the different lattice constants of the substrate, the CeTaN 3 The films are subjected to varying degrees of compressive stress.

[0023] Preferably, in the method described in the present invention, the substrate is SrTiO 3 (011), Si(001), SiC(0001) or GaN(0001), the single crystal CeTaN 3 The film was oriented in the (011) direction.

[0024] In the present invention, the substrate has different crystal orientations, single crystal CeTaN 3 Thin film materials have different orientations.

[0025] Preferably, in the method of the present invention, the annealing in step (2) is carried out under the following conditions: the pressure of ammonia is 10000-15000 Pa, the annealing temperature is 600-1000° C., and the annealing time is 30-120 minutes.

[0026] Preferably, in the method of the present invention, the annealing in step (2) is carried out under the following conditions: the heating rate of the system is controlled so that the system is heated to the annealing temperature within 5 minutes.

[0027] Preferably, in the method of the present invention, the step (1) of growing amorphous CeTaN on the substrate surface 3 The film was made under the following conditions:

[0028] The growth temperature is 20-700℃ and the laser energy density is 0.2-2J / cm 2 , the laser repetition frequency is 2-10Hz.

[0029] In a specific embodiment of the present invention, the preparation method of the present invention may include the following steps:

[0030] (1) Prepare a layer of amorphous CeTaN on the substrate by pulsed laser deposition 3 To avoid oxidation during the growth process, the vacuum degree in the chamber must be higher than 10 -5Pa; the growth temperature can be between 20 and 700°C, preferably 500-700°C; the laser is preferably a XeCl excimer laser (308nm), and the laser energy density is 0.2-2J / cm 2 , preferably 0.5-1J / cm 2 The laser repetition frequency is 2-10 Hz, preferably 3-5 Hz. Optionally, nitrogen plasma irradiation can be used as an auxiliary during the growth process to replenish nitrogen vacancies formed during the film deposition process.

[0031] (2) Rapid annealing in an ammonia atmosphere to make amorphous CeTaN 3 The film is formed into a single crystal film. Preferably, a rapid annealing furnace is used for this operation. First, the vacuum degree in the chamber needs to be pumped to above 0.1 Pa to avoid CeTaN 3 The film is oxidized; ammonia is introduced to 10000-15000Pa, and the air intake is maintained between 1-3slpm to ensure a stable ammonia atmosphere in the chamber. When the ammonia atmosphere is stable, the temperature is quickly raised to 800℃ within 5 minutes and kept at this temperature for 30-120 minutes to make CeTaN 3 The film recrystallizes to form single crystal CeTaN 3 During the cooling process, it is preferred to keep the ammonia atmosphere until the temperature drops below 200°C.

[0032] In a third aspect, the present invention provides an application of the perovskite ferroelectric nitride thin film material of the present invention or the perovskite ferroelectric nitride thin film material prepared by the method of the present invention in a transistor or a non-volatile memory device. For example, the perovskite ferroelectric nitride thin film material of the present invention can be used in a field effect transistor, a ferroelectric tunnel junction or a non-volatile memory.

[0033] The present invention has the following beneficial effects:

[0034] (1) Different from the existing ferroelectric thin film material preparation technology, single crystal CeTaN 3 Thin film materials do not rely on strict growth conditions. Specifically, amorphous CeTaN is prepared by pulsed laser deposition technology. 3 The thin film has a wide growth range, and there is no need to optimize a particular growth parameter to improve the crystal quality. In addition, rapid annealing in an ammonia atmosphere only requires controlling the ammonia atmosphere, which greatly reduces the single crystal CeTaN 3 Difficulty in preparing thin film materials.

[0035] (2) Single crystal CeTaN 3 Thin film materials can not only be grown on conventional oxide substrates such as SrTiO 3It can also be grown directly on substrates commonly used in current silicon-based semiconductor technology, such as Si, SiC and GaN, which is of great value for exploring the application of new functional nitrides.

[0036] (3) The single crystal perovskite ferroelectric nitride thin film material of the present invention can exist stably at room temperature, has excellent crystal quality and has significant ferroelectricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, wherein:

[0038] Figure 1 A schematic diagram showing the crystal structure of the single crystal perovskite type ferroelectric nitride thin film material of the present invention;

[0039] Figure 2 The (001) oriented single crystal thin film material CeTaN prepared in Example 1 of the present invention is shown. 3 XRD pattern of

[0040] Figure 3 The (011) oriented single crystal thin film material CeTaN prepared in Example 3-6 of the present invention is shown. 3 XRD pattern of

[0041] Figure 4 The (001) oriented single crystal thin film material CeTaN prepared in Example 1 of the present invention is shown. 3 Scanning transmission electron micrograph of

[0042] Figure 5 The (011) oriented single crystal thin film material CeTaN prepared in Example 2 and Example 3 of the present invention is shown in FIG. 3 Piezoelectric response test diagram;

[0043] Figure 6 The (011) oriented single crystal thin film material CeTaN prepared in Example 3 of the present invention 3 Standard ferroelectric polarization test curve;

[0044] Figure 7 The (011) oriented single crystal thin film material CeTaN prepared in Example 2 of the present invention is shown. 3 STEM diagram of

[0045] Figure 8 The (011) oriented single crystal thin film material CeTaN prepared in Example 5 of the present invention is shown. 3 STEM image of the experiment. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with specific embodiments. The given examples are only for illustrating the present invention, but not for limiting the scope of the present invention.

[0047] Example 1

[0048] On the substrate SrTiO 3 Preparation of (001) oriented single crystal CeTaN thin film on (001) 3

[0049] (1) Select single crystal SrTiO 3 (001) is the substrate (the substrate root mean square roughness is less than 2 nm) and the surface is cleaned. Specifically, the substrate is ultrasonicated in alcohol, acetone and deionized water for 15 minutes respectively, and then quickly dried with a nitrogen gun.

[0050] (2) Growth of 100nm thick amorphous CeTaN by laser pulse deposition 3 To prevent the film from being oxidized, the growth atmosphere was set to a high vacuum environment, where the back vacuum was higher than 10 -5 The following growth conditions were used: XeCl excimer laser (wavelength 308 nm) was used as the light source, and the laser power density was 1 J / cm 2 , frequency is 5Hz, the target material used is CeTaN 3 Polycrystalline target, the distance between target and substrate is 5 cm, and the film growth temperature is 550℃.

[0051] (3) The amorphous CeTaN obtained in step (2) is placed on the substrate 3 The film was placed in a 15000Pa ammonia atmosphere, rapidly heated to 800°C, and annealed for one hour.

[0052] Before the formal annealing, the vacuum degree of the cavity is first evacuated to above 0.1Pa. Then, 500Pa of ammonia is introduced to clean the cavity. The ammonia gas flow rate is controlled at 2slpm and the ammonia gas flow rate is kept stable. The temperature is quickly raised to 800°C within 1 minute, and the temperature fluctuation does not exceed 1°C. After the annealing is completed, the ammonia gas is also kept in the cooling stage until the temperature drops below 200°C and the ammonia gas is stopped. Finally, a (001) oriented single crystal thin film material CeTaN with a thickness of 100nm is obtained. 3 .

[0053] Example 2

[0054] Preparation of (011) oriented single crystal CeTaN thin film on Si (001) substrate 3

[0055] (1) Si (001) was selected as the substrate. The substrate Si (001) was treated with 20% hydrofluoric acid to remove the surface oxide layer, and then rinsed in flowing deionized water for 1 minute, and then quickly placed in a pulsed laser deposition chamber and evacuated.

[0056] (2) Growth of 15nm thick amorphous CeTaN by laser pulse deposition 3 To prevent the film from being oxidized, the growth atmosphere was set to a high vacuum environment, where the back vacuum was higher than 10 -5 The following growth conditions were used: XeCl excimer laser (wavelength 308 nm) was used as the light source, and the laser power density was 1.5 J / cm 2 , frequency is 5Hz, the target material used is CeTaN 3 Polycrystalline target, the distance between target and substrate is 5 cm, and the film growth temperature is 400℃.

[0057] (3) The amorphous CeTaN obtained in step (2) is placed on the substrate 3 The film was placed in a 10000Pa ammonia atmosphere, rapidly heated to 800°C, and annealed for one hour.

[0058] Before the formal annealing, the vacuum degree of the cavity is first evacuated to above 0.1Pa. Then, 500Pa of ammonia is introduced to clean the cavity. The ammonia gas flow rate is controlled at 2slpm and the ammonia gas flow rate is kept stable. The temperature is quickly raised to 800℃ within 1 minute, and the temperature fluctuation does not exceed 1℃; after the annealing is completed, the ammonia gas is also kept in the cooling stage until the temperature drops below 200℃ and the ammonia gas is stopped. Finally, a (011) oriented single crystal thin film material CeTaN with a thickness of 15nm is obtained. 3 .

[0059] Example 3

[0060] Preparation of (011) oriented single crystal CeTaN thin film on Si (001) substrate 3

[0061] (1) Si (001) was selected as the substrate. The substrate Si (001) was treated with 20% hydrofluoric acid to remove the surface oxide layer, and then rinsed in flowing deionized water for 1 minute, and then quickly placed in a pulsed laser deposition chamber and evacuated.

[0062] (2) Growth of 80nm thick amorphous CeTaN by laser pulse deposition 3 To prevent the film from being oxidized, the growth atmosphere was set to a high vacuum environment, where the back vacuum was higher than 10 -5 The following growth conditions were used: XeCl excimer laser (wavelength 308 nm) was used as the light source, and the laser power density was 1.5 J / cm 2 , frequency is 5Hz, the target material used is CeTaN 3 Polycrystalline target, the distance between target and substrate is 5 cm, and the film growth temperature is 400℃.

[0063] (3) The amorphous CeTaN obtained in step (2) is placed on the substrate 3The film was placed in a 10000Pa ammonia atmosphere, rapidly heated to 800°C, and annealed for one hour.

[0064] Before the formal annealing, the vacuum degree of the cavity is first evacuated to above 0.1Pa. Then, 500Pa of ammonia is introduced to clean the cavity. The ammonia gas flow rate is controlled at 2slpm and the ammonia gas flow rate is kept stable. The temperature is quickly raised to 800℃ within 1 minute, and the temperature fluctuation does not exceed 1℃; after the annealing is completed, the ammonia gas is also kept in the cooling stage until the temperature drops below 200℃ and the ammonia gas is stopped. Finally, a (011) oriented single crystal thin film material CeTaN with a thickness of 80nm is obtained. 3 .

[0065] Example 4

[0066] On the substrate SrTiO 3 Preparation of (011) oriented single crystal CeTaN thin film on (011) 3

[0067] (1) Select single crystal SrTiO 3 (011) is a substrate (the root mean square roughness of the substrate is less than 2 nm) and the surface is cleaned. Specifically, the substrate is ultrasonicated in alcohol, acetone and deionized water for 15 minutes respectively, and then quickly blown dry with a nitrogen gun.

[0068] (2) Growth of 100nm thick amorphous CeTaN by laser pulse deposition 3 To prevent the film from being oxidized, the growth atmosphere was set to a high vacuum environment, where the back vacuum was higher than 10 -5 The following growth conditions were used: XeCl excimer laser (wavelength 308 nm) was used as the light source, and the laser power density was 0.5 J / cm 2 , frequency is 3Hz, target material used is CeTaN 3 Polycrystalline target, the distance between target and substrate is 5 cm, and the film growth temperature is 700℃.

[0069] (3) The amorphous CeTaN obtained in step (2) is placed on the substrate 3 The film was placed in a 15000Pa ammonia atmosphere, rapidly heated to 1000°C, and annealed for one hour.

[0070] Before the formal annealing, the vacuum degree of the cavity is first evacuated to above 0.1Pa. Then, 500Pa of ammonia is introduced to clean the cavity. The ammonia gas flow rate is controlled at 2slpm and the ammonia gas flow rate is kept stable. The temperature is quickly raised to 1000°C within 1 minute, and the temperature fluctuation does not exceed 1°C. After the annealing is completed, the ammonia gas is also kept in the cooling stage until the temperature drops below 200°C and the ammonia gas is stopped. Finally, a (011) oriented single crystal thin film material CeTaN with a thickness of 100nm is obtained. 3 .

[0071] Example 5

[0072] Preparation of (011) oriented single crystal CeTaN thin film on SiC (0001) substrate 3

[0073] (1) Select single-crystal SiC(0001) as the substrate (the root mean square roughness of the substrate is less than 2 nm) and perform surface cleaning. Specifically, ultrasonically clean the substrate in alcohol, acetone, and deionized water for 15 minutes each, and quickly dry it with a nitrogen gun.

[0074] (2) Grow a 100-nm-thick amorphous CeTaN 3 thin film. To avoid oxidation of the thin film, the growth atmosphere is set to a high-vacuum environment, where the background vacuum degree is higher than 10 -5 Pa. The following growth conditions are adopted: Use a XeCl excimer laser (wavelength 308 nm) as the light source, the laser power density is 1 J / cm 2 , the frequency is 5 Hz, the target used is a CeTaN 3 polycrystalline target, the distance between the target and the substrate is 5 cm, and the thin film growth temperature is 600 °C.

[0075] (3) Place the amorphous CeTaN 3 thin film obtained in step (2) on the substrate in an ammonia atmosphere of 15000 Pa, quickly heat it to 700 °C, and anneal for one hour.

[0076] Before the formal annealing, first pump the vacuum degree of the cavity to higher than 0.1 Pa. Then, introduce 500 Pa of ammonia to clean the cavity. The ammonia gas flow rate is controlled at 2 slpm and the ammonia gas flow rate is kept stable. Quickly heat it to 700 °C within 1 minute, and the temperature fluctuation does not exceed 1 °C. Keep ammonia introduced during the cooling stage after annealing until the temperature drops below 200 °C and then stop introducing ammonia. Finally, obtain a 100-nm-thick single-crystal thin film material CeTaN 3 with (011) orientation.

[0077] Example 6

[0078] Preparation of (011) oriented single crystal CeTaN thin film on GaN (0001) substrate 3

[0079] (1) Select single-crystal GaN(0001) as the substrate (the root mean square roughness of the substrate is less than 2 nm) and perform surface cleaning. Specifically, ultrasonically clean the substrate in alcohol, acetone, and deionized water for 15 minutes each, and quickly dry it with a nitrogen gun.

[0080] (2) Grow a 100-nm-thick amorphous CeTaN 3To prevent the film from being oxidized, the growth atmosphere was set to a high vacuum environment, where the back vacuum was higher than 10-5 Pa. The following growth conditions were used: XeCl excimer laser (wavelength 308 nm) was used as the light source, and the laser power density was 1 J / cm 2 , frequency is 5Hz, the target material used is CeTaN 3 Polycrystalline target, the distance between target and substrate is 5 cm, and the film growth temperature is 20℃.

[0081] (3) The amorphous CeTaN obtained in step (2) is placed on the substrate 3 The film was placed in a 15000Pa ammonia atmosphere, rapidly heated to 600°C, and annealed for one hour.

[0082] Before the formal annealing, the vacuum degree of the cavity is first evacuated to above 0.1Pa. Then, 500Pa of ammonia is introduced to clean the cavity. The ammonia gas flow rate is controlled at 2slpm and the ammonia gas flow rate is kept stable. The temperature is quickly raised to 600°C within 1 minute, and the temperature fluctuation does not exceed 1°C. After the annealing is completed, ammonia is also kept in the cooling stage until the temperature drops below 200°C and the introduction of ammonia is stopped. Finally, a (011) oriented single crystal thin film material CeTaN with a thickness of 100nm is obtained. 3 .

[0083] Performance Characterization

[0084] Figure 1 The crystal structure schematic diagram of the single crystal perovskite type ferroelectric nitride thin film material of the present invention is shown. The single crystal thin film material CeTaN of the present invention 3 It is a perovskite material, with Ce in its primitive cell 4+ Occupying eight corner positions, Ta 5+ Occupies the center of the body, and 6 N 3- It occupies all face-centered points to form an octahedral structure.

[0085] Figure 2 The (001) oriented single crystal thin film material CeTaN prepared in Example 1 of the present invention is shown. 3 XRD pattern of Figure 2 XRD spectrum of CeTaN 3 The lattice constant of the perovskite ferroelectric nitride thin film material of the present invention is calculated by (002) diffraction angle: Figure 3 The (011) oriented single crystal thin film material CeTaN prepared in Example 3-6 of the present invention is shown. 3 XRD pattern of .

[0086] The amorphous CeTaN was characterized by a high-resolution four-circle X-ray diffractometer (Malvern Panalytical, X'Pert3 MRD). 3 Thin films and single-crystalline CeTaN with different orientations grown on different substrates 3 The film was tested by X-ray diffraction, which showed that CeTaN grown only by pulsed laser deposition technology 3 The film is in an amorphous state, and the CeTaN film after rapid annealing in an ammonia atmosphere 3 The film is a single crystal, which is grown on SrTiO 3 Single crystal CeTaN on (001) 3 The film material is (001) oriented, such as Figure 2 As shown. Grown on SrTiO 3 Single crystal CeTaN on (011) and Si(001), SiC(0001) and GaN(0001) substrates 3 The film material is (011) oriented, such as Figure 3 shown.

[0087] Figure 2 and Figure 3 The single crystal thin film material CeTaN of the present invention is also shown 3 It has low formation energy and excellent stability and can exist stably at room temperature.

[0088] Figure 4 The (001) oriented single crystal thin film material CeTaN prepared in Example 1 of the present invention is shown. 3 The single crystal CeTaN of Example 1 was imaged by an ARM-200CF scanning transmission electron microscope (STEM) at an accelerating voltage of 200 keV. 3 The atomic structure of the thin film material was characterized. Atomic-resolution STEM images show that single-crystalline CeTaN 3 The film material has excellent crystalline quality, the atomic columns are clearly visible, and it has a distinct perovskite structure. In addition, significant atomic displacements can be observed, proving the existence of its polarity.

[0089] Figure 5 The (011) oriented single crystal thin film material CeTaN prepared in Example 2 and Example 3 of the present invention is shown in FIG. 3 Piezoelectric response test diagram. Piezoelectric response test was performed using Asylum MFP-3D atomic force microscope. In the piezoelectric response test, 15nm and 80nm thick CeTaN 3The film has significant ferroelectric domains. With the change of the tip bias, the phase flips 180° and the amplitude shows a significant butterfly loop. Further domain writing test, when the bias voltage is +12V, the CeTaN 3 The surface of the film is written with "CeTaN 3 "Domain reversal region, such as Figure 5 shown.

[0090] Figure 6 The (011) oriented single crystal thin film material CeTaN prepared in Example 3 of the present invention is shown. 3 Standard ferroelectric polarization test curve. Before the test, thermal evaporation technology was used to deposit the single crystal CeTaN 3 The Pt top electrode with a diameter of 20 μm and a thickness of 50 nm was evaporated on the film surface. The single crystal CeTaN 3 The thin film material was subjected to standard ferroelectric polarization tests and a significant hysteresis loop was obtained. 3 The ferroelectric polarization of Ce 4+ The d orbitals of the ions and N 3- driven by the p-orbital hybridization of the ions. Figure 6 The single crystal CeTaN 3 The ferroelectric polarization value of the thin film material is about 18μC / cm 2 , and there is a significant reversal current at the coercive field, which directly proves that CeTaN 3 The film has significant ferroelectricity.

[0091] Figure 7 The (011) oriented single crystal thin film material CeTaN prepared in Example 2 of the present invention is shown. 3 The single crystal CeTaN of Example 2 was imaged by an ARM-200CF scanning transmission electron microscope (STEM) at an accelerating voltage of 200 keV. 3 The atomic structure of the thin film material was characterized. STEM images show that the (011) oriented CeTaN 3 The atomic columns of the thin film material are clearly visible, proving its excellent crystalline quality. 3 There is a naturally formed SiO layer about 2 nm thick between the film and the Si (001) substrate. 2 layer.

[0092] Figure 8 The (011) oriented single crystal thin film material CeTaN prepared in Example 5 of the present invention is shown. 3 The single crystal CeTaN of Example 5 was imaged by an ARM-200CF scanning transmission electron microscope (STEM) at an accelerating voltage of 200 keV.3 The atomic structure of the thin film material was characterized. STEM images show that CeTaN 3 There is a sharp boundary between the film and the substrate. (011) oriented CeTaN 3 The atomic columns of the thin film material are clearly visible, demonstrating its excellent crystalline quality.

Claims

1. A perovskite-type ferroelectric nitride thin film material, which is a single crystal and has the following chemical formula: CeTaN3.

2. The perovskite ferroelectric nitride thin film material according to claim 1, wherein: The lattice constant of the perovskite ferroelectric nitride thin film material is The space group is P4mm.

3. The perovskite ferroelectric nitride thin film material according to claim 1, wherein: The indirect band gap of the perovskite-type ferroelectric nitride thin film material is 1.06 eV.

4. The perovskite ferroelectric nitride thin film material according to claim 1, wherein: The ferroelectric polarization value of the perovskite-type ferroelectric nitride thin film material is 15-30 μC / cm 2 .

5. The perovskite ferroelectric nitride thin film material according to claim 1, wherein: The perovskite-type ferroelectric nitride thin film material has a (001) orientation or a (011) orientation.

6. A method for preparing the perovskite-type ferroelectric nitride thin film material according to any one of claims 1 to 5, comprising the following steps: (1) Using laser pulse deposition technology to grow amorphous CeTaN3 thin film on the substrate surface; (2) Annealing the amorphous CeTaN3 thin film in an ammonia atmosphere to form a single crystal CeTaN3 thin film.

7. The method according to claim 6, further comprising the following step before step (1): cleaning the surface of the substrate.

8. The method according to claim 6, wherein: The substrate is LaAlO3(001), SrTiO3(001), (LaAlO3) 0.3 -(Sr2AlTaO6) 0.7 (001), SrTiO3(011), Si(001), SiC(0001) or GaN(0001); Preferably, the substrate is LaAlO3(001), SrTiO3(001) or (LaAlO3) 0.3 -(Sr2AlTaO6) 0.7 (001), the orientation of the single crystal CeTaN3 film is (001); Preferably, when the substrate is SrTiO3(011), Si(001), SiC(0001) or GaN(0001), the orientation of the single crystal CeTaN3 film is (011).

9. The method according to claim 6, wherein: The annealing in step (2) is carried out under the following conditions: the pressure of ammonia is 10000-15000 Pa, the annealing temperature is 600-1000° C., and the annealing time is 30-120 minutes; More preferably, the annealing in step (2) is carried out under the following conditions: the heating rate of the system is controlled so that the system is heated to the annealing temperature within 5 minutes; Preferably, the step (1) of growing an amorphous CeTaN3 film on the substrate surface is carried out under the following conditions: The growth temperature is 20-700℃ and the laser energy density is 0.2-2J / cm 2 , the laser repetition frequency is 2-10Hz.

10. Use of the perovskite ferroelectric nitride thin film material according to any one of claims 1 to 5 or the perovskite ferroelectric nitride thin film material prepared by the method according to any one of claims 6 to 9 in a transistor or a non-volatile memristor device.

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