A novel gallium nitride nickel nitrogen vacancy color center and a preparation method thereof

Abstract

The application discloses a novel gallium nitride nickel nitrogen vacancy color center and a preparation method thereof, and mainly solves the problems of high color center preparation cost, high optical excitation energy and limited application in the prior art. The scheme comprises the following steps: in a gallium nitride lattice, a nickel atom is used to replace a gallium atom and a nearest-neighbor nitrogen vacancy of the gallium atom, atomic arrangement presents C 3v symmetry, and a C 3v symmetry axis passes through the center of the nickel atom and the nitrogen vacancy, and is perpendicular to the plane where three gallium atoms with equal spacing are located; and the preparation method is that first, a cubic phase gallium nitride film is grown by using a metal organic chemical vapor deposition method, then, ion implantation is carried out on the gallium nitride film, specific types of nickel ions are doped, and after high-temperature annealing is performed to repair lattice damage, a large number of single vacancies are generated through electronic irradiation, and then rapid annealing is carried out again. The application can effectively reduce the optical excitation energy required for operating the color center, reduce the color center preparation cost, and can be widely applied to the fields of measurement, communication, simulation, high-performance calculation and the like.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials technology, and further relates to color centers in solid-state systems, specifically a novel gallium nickel nitride nitrogen vacancy color center and its preparation method, which can be used in quantum sensor devices. Background Technology

[0002] Color centers in solid-state systems have broad application prospects in sensing and measurement, communication, simulation, and high-performance computing. After years of development, nitrogen-vacancy (NV) color centers in diamond play a crucial role in emerging quantum technologies due to their excellent optical properties and long spin coherence time. Although the potential of diamond NV color centers has been demonstrated in quantum technology applications, their high hardness, difficulty in micro / nano fabrication and doping, and other challenges hinder their practical application. Therefore, exploring other technologically mature and low-cost wide-bandgap semiconductor materials as host materials for color centers is particularly important.

[0003] As a third-generation semiconductor material, GaN possesses a wide direct bandgap of 3.4 eV, excellent chemical stability, and good thermal conductivity. High-quality GaN thin film single crystals, grown using mature techniques, avoid interference from other defects and impurities with the spin state of color centers and exhibit weak spin-orbit coupling, making them ideal host materials for color center fabrication. Transition metals, due to their unique electronic structures, can modulate the magnetism of the host material and achieve ideal spin injection, which is beneficial for realizing paramagnetic color centers with intrinsically spin-conserving optical excitation.

[0004] A patent document entitled "A Method for Preparing Nanodiamond Transition Metal Color Centers by Seeding and Doping," publication number CN111705305B, discloses a method for preparing nanodiamond titanium color centers. This method involves ultrasonically seeding a diamond substrate with a mixture of nanodiamond seeds and transition metal particles to achieve a uniform distribution of the mixed seeds. A nanodiamond film is then grown on the surface of the seeded diamond substrate, and high-temperature annealing is used to obtain diamond with transition metal color centers. This preparation method achieves relatively pure nanodiamond transition metal color centers. However, the diamond films prepared using this method are composed of many small grains, rather than a "single-crystal structure." This grain structure severely affects the electrical and optical properties of the diamond. Furthermore, the color center concentration obtained by this method is low, and precise position control is difficult to achieve. The optical excitation energy required for measuring the spin bit state of the color centers is high.

[0005] In their paper "Room temperature solid-state quantum emitters in the telecom range," Yu Zhou et al. reported the presence of color centers in Mg-doped gallium nitride (GaN) thin film samples. These samples achieved color centers with high brightness and optical stability, exhibiting fluorescence peaks in the near-infrared band. Such color centers are more easily formed in p-type GaN. However, the conductivity of p-type GaN doped layers remains limited, hindering the application of these devices.

[0006] Diamond-based transition metal color centers are excellent near-infrared single-photon sources; however, diamond's high hardness and processing difficulty limit its practical applications. High-quality gallium nitride (GaN) films are also suitable materials for preparing color centers. Existing GaN color centers are easier to form in p-type GaN, but the limited conductivity of p-type GaN doped layers restricts their applications. Therefore, there is an urgent need to explore a novel color center material with low optical excitation energy, easy processing, and stable existence in n-type GaN. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a novel gallium nitride nickel nitrogen vacancy color center and its preparation method. This addresses the problems of high preparation cost, high optical excitation energy, and the fact that existing color centers only exist in p-type doped layers with limited conductivity within the gallium nitride host. First, cubic gallium nitride is used as the epitaxial layer. Through nickel ion implantation and electron irradiation, followed by thermal annealing, a novel structure of gallium nitride nickel nitrogen vacancy color centers is formed. This invention can improve the position of the Fermi surface corresponding to the stable existence of electrically neutral gallium nitride color centers, reduce the optical excitation energy required to manipulate the color centers, and reduce the preparation cost.

[0008] The specific solution for achieving the above-mentioned objective of this invention includes: in a gallium nitride lattice, using a nickel atom to replace a gallium atom and the nearest-neighbor nitrogen vacancy of that gallium atom to form a complex, namely a gallium nitride nickel nitrogen vacancy color center; the atomic arrangement of the complex exhibits C 3v Symmetrical, and C 3v The axis of symmetry passes through the center of the nickel atom and the nitrogen vacancy and is perpendicular to the plane containing the three equally spaced gallium atoms. The method for preparing the above-mentioned gallium nickel nitride nitrogen vacancy color center includes the following steps:

[0009] (1) Select a substrate and pre-treat it to obtain a pre-treated flat substrate;

[0010] (2) An unintentionally doped epitaxial layer, namely a cubic gallium nitride thin film, is grown on a flat substrate using metal-organic chemical vapor deposition (MOCVD).

[0011] (3) Ion implantation of the epitaxial layer:

[0012] Nickel ions were implanted into gallium nitride thin films at 170 keV to obtain ion-implanted samples, which were then subjected to rapid annealing at 800 °C under a nitrogen atmosphere.

[0013] (4) Apply 10 MeV energy and 5 × 10 to the sample obtained in step (3). 17 cm -2 The sample was subjected to electron irradiation of a specific dose, and then rapidly annealed at 600–800 °C in a nitrogen atmosphere.

[0014] (5) Complete the preparation of gallium nitride nickel nitrogen vacancy color centers.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] First, because this invention uses gallium nitride as the main material, the processing difficulty of the color center is reduced, thereby reducing the production cost of the color center.

[0017] Secondly, since this invention uses cubic gallium nitride as the main material, the large lattice constant of cubic gallium nitride reduces the splitting between the ground state and excited state of the color center, thereby reducing the optical excitation energy for manipulating the color center. This property is superior to that of diamond color centers.

[0018] Third, because the present invention uses nickel and nitrogen vacancy co-doping, the formation energy of the designed color center is low and it has higher chemical stability. When the electrically neutral color center exists stably, the corresponding Fermi surface is close to the bottom of the conduction band, thus allowing it to exist stably in n-type doped gallium nitride. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation process of the vacancy color center in this invention;

[0020] Figure 2 The diagram shows the density of states and band structure of the vacancy color centers in this invention.

[0021] Figure 3 This is a positional coordinate diagram of the vacant color center in this invention;

[0022] Figure 4 This is a schematic diagram of the structure of the vacant color center in this invention; Detailed Implementation

[0023] The present invention will now be further described with reference to the accompanying drawings.

[0024] See attached document Figure 4 The present invention proposes a novel gallium nickel nitride nitrogen vacancy color center, comprising:

[0025] In a gallium nitride (GaN) lattice, a complex is formed by replacing a gallium atom with a nearest-neighbor nitrogen vacancy using a nickel atom, known as a gallium nitride nickel nitrogen vacancy color center; the atomic arrangement of this complex exhibits a Ci pattern. 3v Symmetrical, and C 3v The axis of symmetry passes through the center of the nickel atom and the nitrogen vacancy, and is perpendicular to the plane containing the three equally spaced gallium atoms.

[0026] See attached document Figure 1 This invention proposes a novel method for preparing gallium nitride nickel nitrogen vacancy centers. The method utilizes ion implantation to dope specific types of nickel ions, followed by high-temperature annealing to repair lattice damage. A large number of single vacancies are then generated through electron irradiation, followed by rapid annealing to complete the preparation. The specific steps include:

[0027] Step 1. Select a substrate and pre-treat it to obtain a pre-treated flat substrate; suitable substrates include gallium arsenide substrates, sapphire substrates, gallium nitride substrates, etc. In this embodiment, the pre-treatment process involves cleaning the substrate in an ultrasonic cleaner, followed by sequential cleaning with acetone for 3-5 minutes, ethanol for 3-5 minutes, and isoacetone for 3-5 minutes to remove oil stains from the substrate surface; then soaking it in hydrochloric acid aqueous solution for 3-5 minutes to remove the oxide layer on the surface; finally, ultrasonic cleaning is performed with deionized water, and the substrate is then dried with nitrogen gas.

[0028] Step 2. An unintentionally doped epitaxial layer, namely a cubic gallium nitride thin film, is grown on a flat substrate using metal-organic chemical vapor deposition (MOCVD). In this embodiment, the unintentionally doped epitaxial layer is grown using MOCVD, with trimethylgallium (TMGa) and ammonia (NH3) as the gallium and nitrogen sources, respectively, at flow rates of 120 sccm and 1200 sccm; H2 is used as the gallium source carrier gas; the substrate is first baked at 1150℃ in an H2 atmosphere for 10 minutes, then cooled to 550℃~580℃ to grow a GaN buffer layer for 5 minutes, and then heated to 900℃ to grow an undoped GaN epitaxial layer; the thickness of the epitaxial layer is 2~5 μm.

[0029] Step 3. Perform ion implantation on the epitaxial layer:

[0030] Nickel ions were implanted into a gallium nitride thin film at 170 keV. In this embodiment, a conventional implantation dose of 1×10⁻⁶ was used. 16 cm -2 The ion-implanted sample was obtained and then subjected to rapid annealing at 800°C under a nitrogen atmosphere.

[0031] Step 4. Apply 10 MeV energy and 5 × 10⁻⁶ m³ / s to the sample obtained in Step 3. 17 cm -2The sample was subjected to electron irradiation of a specific dose, and then rapidly annealed at 600–800 °C in a nitrogen atmosphere.

[0032] Step 5. Complete the preparation of gallium nitride nickel nitrogen vacancy color centers.

[0033] Color centers in solid-state systems have broad application prospects in sensing and measurement, communication, simulation, and high-performance computing. GaN material, with its wide direct bandgap of 3.4 eV, excellent chemical stability, and good thermal conductivity, is a semiconductor material resistant to strong radiation in harsh environments and is widely used in 5G communication, aerospace, and other fields. High-quality GaN thin-film single crystals avoid interference from other defects and impurities with the spin state of the color centers and possess weak spin-orbit coupling, making them very suitable host materials for preparing color centers. Transition metal elements, due to their unique electronic structures, can control the magnetism of the host material and achieve ideal spin injection, which is beneficial for realizing paramagnetic color centers with intrinsic spin-conserving optical excitation. The potential of NV color centers in diamond has already been demonstrated in quantum technology applications, but its high hardness, difficulty in micro / nano fabrication and doping, pose significant challenges to its practical application. Existing gallium nitride color centers are not intentionally prepared; their formation is uncontrolled, and their type and position are uncertain, thus limiting the application of gallium nitride color centers. This invention prepares novel gallium nitride nickel nitrogen vacancy color centers by nickel ion implantation and electron irradiation, which does not require high production costs of color center host materials, reduces the optical excitation energy of color centers, decreases lattice relaxation, and has a wider range of applications.

[0034] The parts of this invention not described in detail are common knowledge to those skilled in the art.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Obviously, those skilled in the art, after understanding the content and principle of the present invention, may make various modifications and changes in form and detail without departing from the principle and structure of the present invention. However, these modifications and changes based on the concept of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A novel method for preparing gallium nickel nitride nitrogen vacancy color centers, characterized in that... The preparation process involves using ion implantation to dope specific types of nickel ions, followed by high-temperature annealing to repair lattice damage, generating a large number of single vacancies through electron irradiation, and then rapid annealing to complete the fabrication. The specific steps include: (1) Select a substrate and pre-treat it to obtain a pre-treated flat substrate; (2) An unintentionally doped epitaxial layer, namely a cubic gallium nitride thin film with a thickness of 2 to 5 μm, is grown on a flat substrate by metal-organic chemical vapor deposition (MOCVD). (3) Ion implantation of the epitaxial layer: Nickel ions were implanted into a gallium nitride thin film at 170 keV, with an implantation dose of 1 × 10⁻⁶. 16 cm -2 The ion-implanted sample was obtained and then subjected to rapid annealing at 800°C under a nitrogen atmosphere. (4) Apply 10 MeV energy and 5 × 10 to the sample obtained in step (3). 17 cm -2 The sample was subjected to electron irradiation of a specific dose, and then rapidly annealed at 600–800 °C in a nitrogen atmosphere. (5) Complete the preparation process of gallium nitride nickel nitrogen vacancy color centers to obtain gallium nitride nickel nitrogen vacancy color centers that exist stably in n-type doped gallium nitride.

2. The method according to claim 1, characterized in that: The substrates selected in step (1) include gallium arsenide substrates, sapphire substrates, and gallium nitride substrates.

3. The method according to claim 1, characterized in that: The pretreatment described in step (1) includes cleaning the substrate in an ultrasonic cleaner, then cleaning it sequentially with acetone for 3-5 minutes, ethanol for 3-5 minutes, and isoacetone for 3-5 minutes to remove oil stains from the substrate surface; then soaking it in hydrochloric acid aqueous solution for 3-5 minutes to remove the oxide layer on the surface; finally ultrasonic cleaning with deionized water, and then drying it with nitrogen gas.

4. The method according to claim 1, characterized in that: In step (2), an unintentionally doped epitaxial layer is grown using metal-organic chemical vapor deposition (MOCVD). Trimethylgallium (TMGa) and ammonia (NH3) are used as gallium and nitrogen sources, respectively, and H2 is used as the gallium source carrier gas. First, the substrate is baked at 1150°C in an H2 atmosphere for 10 minutes, then the temperature is lowered to 550°C to 580°C to grow a GaN buffer layer for 5 minutes, and then the temperature is raised to 900°C to grow an undoped GaN epitaxial layer.

5. The method according to claim 4, characterized in that: The flow rates of the gallium source and the nitrogen source are 120 sccm and 1200 sccm, respectively.

6. A gallium nickel nitride nitrogen vacancy color center prepared by the method according to claim 1, characterized in that: In a gallium nitride (GaN) lattice, a complex is formed by replacing a gallium atom with a nearest-neighbor nitrogen vacancy using a nickel atom, known as a gallium nitride nickel nitrogen vacancy color center; the atomic arrangement of this complex exhibits a Ci pattern. 3v Symmetrical, and C 3v The axis of symmetry passes through the center of the nickel atom and the nitrogen vacancy and is perpendicular to the plane containing three equally spaced gallium atoms; the gallium nitride nickel nitrogen vacancy color center exists stably in n-type doped gallium nitride.

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