阅读说明：本技术 一种通过离子注入制备金刚石氮镍复合色心的方法 (Method for preparing diamond nitrogen-nickel composite color center through ion implantation ) 是由 李成明 郑宇亭 刘金龙 魏俊俊 陈良贤 于 2019-10-28 设计创作，主要内容包括：一种通过离子注入制备金刚石氮镍复合色心的方法,属于光电器件用基体材料制备领域。步骤为：a.将高质量单晶金刚石抛光到表面粗糙度低于1nm；b.将剂量为高于1×10<Sup>15</Sup>cm<Sup>-2</Sup>低于5×10<Sup>16</Sup>cm<Sup>-2</Sup>的氮离子注入金刚石内部；c.对离子注入后的金刚石进行800℃到1200℃真空或保护气体或真空等离子体高温退火；d.再以与氮离子注入相同深度所需的能量将剂量为注入的氮离子剂量的1/4(或低于1/4)的镍离子注入金刚石；e.对注入后的金刚石再次进行先1000℃到1200℃真空或保护气体或真空等离子体高温退火；f.接着升高退火温度至1400℃促进孤氮形成及氮原子移动；g.再将温度升至1600℃至2000℃,以促进氮镍原子聚合。本发明以通过可控的离子注入方法,实现金刚石氮镍复合色心的精确制备。(A method for preparing a diamond nitrogen-nickel composite color center by ion implantation belongs to the field of preparation of base materials for photoelectric devices. The method comprises the following steps: a. polishing the high-quality single crystal diamond until the surface roughness is lower than 1 nm; b. the dosage is higher than 1 × 10 15 cm ‑2 Less than 5X 10 16 cm ‑2 The nitrogen ions are implanted into the diamond; c. carrying out high-temperature annealing on the diamond subjected to ion implantation at 800-1200 ℃ in vacuum or protective gas or vacuum plasma; d. and 1/4 (with the energy required for implanting nitrogen ions to the same depth as the nitrogen ions to be implantedOr less than 1/4) nickel ion implanted diamond; e. carrying out high-temperature annealing on the implanted diamond again at the temperature of 1000-1200 ℃ in vacuum or protective gas or vacuum plasma; f. then raising the annealing temperature to 1400 ℃ to promote the formation of nitrogen lone and the movement of nitrogen atoms; g. the temperature is then raised to 1600 to 2000 ℃ to promote the polymerization of the nickel nitrogen atoms. The invention realizes the accurate preparation of the diamond nitrogen-nickel composite color center by a controllable ion implantation method.)

1. A method for preparing the composite color center of diamond nitrogen nickel through ion implantation, characterized by that through the method of ion implantation, after implanting the nitrogen ion of the particular dosage and repairing the radiation damage through the high-temperature annealing, implant and have nickel ion of the same depth and equivalent to 1/4 or lower than the dosage of nitrogen ion, after annealing at high temperature again subsequently, realize and prepare NE8 nitrogen-nickel composite color center accurately;

step 1: grinding and polishing of diamonds

In order to meet the requirements of application and test of electronic devices or photoelectric devices, firstly, high-quality single crystal diamond is precisely polished, and the surface roughness is lower than 1nm after polishing;

step 2: acid washing and pretreatment of diamond:

in order to ensure the surface of the single crystal diamond to be smooth and clean and remove metal impurities, hydrocarbon, graphite and the like which possibly exist, the diamond needs to be pickled and pretreated;

and step 3: injecting nitrogen ions into the diamond;

and 4, step 4: annealing the diamond after nitrogen ion implantation;

and 5: injecting nickel ions after annealing;

step 6: and (5) annealing the diamond after the secondary ion implantation.

2. The method for preparing the diamond nitrogen-nickel composite color center by ion implantation according to claim 1, wherein the precise polishing step in step 1 is as follows: pre-polishing diamond micropowder with granularity of 40 to 20 for 24 to 48 hours; then changing the granularity of the diamond powder to 10 and 2.5 in turn and repeating the steps; then placing on a precision diamond polishing disk, and respectively carrying out 20-80 hours, 40-160 hours and 80-200 hours under the conditions that the rotating speed is 40 revolutions per minute, 80 revolutions per minute and 120 revolutions per minute.

3. The method for preparing the diamond nitrogen-nickel composite color center by ion implantation according to claim 1, wherein the step 2 of acid washing and pretreatment of the diamond comprises the following steps:

after polishing, the diamond samples were placed in HCl: h₂SO₄Boiling the mixed solution at a ratio of 1:5 for 45 minutes to 1 hour, and then washing with deionized water; then the mixture is sequentially placed in acetone solution and absolute ethyl alcohol for ultrasonic cleaning for 10-15 minutes respectively, and then is dried.

4. The method for preparing a diamond nitrogen-nickel composite color center by ion implantation according to claim 1, wherein the step of nitrogen ion implantation of the diamond in the step 3 is as follows:

1) in order to ensure that the average spacing between nitrogen atoms is kept within 2nm after nitrogen ions are implanted into the diamond, the implantation dosage of the nitrogen atoms is higher than 1 x 10¹⁵cm^-2；

2) A great deal of diamond lattice damage can be generated due to the ion implantation process; the damage can realize diamond recovery through high-temperature heat treatment; however, when the concentration of vacancies produced by damage is 1X 10 higher than the concentration of vacancies²²vac/cm³Then irreversible damage can be caused, so that the diamond crystal lattice can not be recovered; therefore, the implantation dosage of nitrogen atom needs to be lower than 5X 10¹⁶cm^-2；

3) In order to avoid the channel effect in a specific crystal direction in the process of ion implantation into the diamond and influence the accuracy of the ion implantation depth, the implantation angle is adjusted to form an included angle of 7 degrees on the surface of the diamond.

5. The method for preparing the diamond nitrogen-nickel composite color center by ion implantation according to claim 1, wherein the annealing treatment step of the diamond after the nitrogen ion implantation in the step 4 is as follows:

1) annealing heat treatment is adopted to eliminate diamond lattice damage caused by ion implantation; in order to ensure that the diamond is not oxidized to form graphite in the heat treatment process, the injected diamond is subjected to high-temperature annealing treatment by adopting vacuum or inert gas protection or vacuum plasma;

2) the annealing temperature is 800 ℃, 1000 ℃ and 1200 ℃ for 1 to 2 hours respectively to ensure that the irradiation-generated vacancies have enough energy and time to move, merge and eliminate.

6. The method for preparing a diamond nitrogen-nickel composite color center by ion implantation according to claim 1, wherein the step of nickel ion implantation after annealing in step 5 is:

1) because the radiuses of the two atoms are different, the energy required to be injected is different; in order to ensure that the nitrogen atoms and the nickel atoms can be polymerized, the injected nitrogen atoms and the nickel atoms are kept at the same injection depth;

2) because the NE8 color center is composed of 4 nitrogen atoms and one nickel atom, in order to ensure the formation of the NE8 composite color center, the injection dosage of the nickel atoms needs to be 1/4 or less than 1/4 of the dosage of the nitrogen atoms;

3) in order to avoid the channel effect in the specific crystal direction during the process of ion implantation into the diamond and influence the accuracy of the ion implantation depth, the implantation angle is adjusted to form an included angle of 7 degrees on the surface of the diamond.

7. The method for preparing the diamond nitrogen-nickel composite color center by ion implantation according to claim 1, wherein the diamond annealing treatment step after the secondary ion implantation in the step 6 is as follows:

1) vacuum or inert gas protection or vacuum plasma high-temperature annealing treatment is adopted, so that the diamond is ensured to realize lattice recovery in the heat treatment process and is not oxidized to form graphite;

2) the annealing temperature needs to be 800 ℃, 1000 ℃ and 1200 ℃ for 1 to 2 hours respectively so as to ensure that the vacancy generated by irradiation has enough energy and time to move, combine and eliminate;

3) subsequently increasing the temperature to 1400 ℃ for 1 to 2 hours to effect dissociation of nitrogen vacancies and movement of nitrogen ions;

4) the temperature is then raised to 1600 to 2000 ℃ for 0.5 to 1 hour to effect mobile polymerization of the nitrogen atoms and formation of NE8 complex color centers.

The technical field is as follows:

the invention relates to the field of photoelectric material application; especially for the field of optical quantum technology in the aspect of quantum information processing and the like. The controllable preparation of the diamond nitrogen-nickel color center is realized by adopting a method of precisely controllable ion implantation, and the single-photon source diamond color center with excellent characteristics and near infrared bands is obtained.

Technical Field

The diamond has extremely excellent physicochemical properties, such as wide forbidden band, high carrier mobility, low dielectric constant, extremely high Johnson index and Keyse index, etc., which are known as ultimate wide forbidden band semiconductors in the fields of high frequency, high power and high temperature withstand voltage, also known as fourth generation semiconductors, diamond is also a material which is known to have a defect color center capable of stably generating a single photon pulse at room temperature, just that the color center of diamond has excellent light stability, high Debye temperature and room temperature controllability, so that the color center of diamond is particularly suitable for the application field of quantum technologies such as quantum computing, quantum key, etc., and the main diamond single photon source comprises a nitrogen vacancy color center (NV), a silicon color center (SiV) and a nitrogen nickel composite color center (NE8), wherein the NV color center is only a small part of all fluorescence thereof, so that the color center has a low collection rate and an excitation state lifetime, which is not reasonably weakened by the thermal treatment of infrared ray, thermal annealing, the thermal treatment of the infrared ray, the thermal energy.

Disclosure of Invention

In order to solve the problems, the invention aims to provide a method for accurately realizing the preparation of a diamond nitrogen-nickel composite color center by an ion implantation method. Polishing high-quality single crystal diamond to extremely low roughness by precision polishing, and then carrying out dosage on the diamond to be 1 multiplied by 10¹⁵cm^-2To 5X 10¹⁶cm^-2After nitrogen ion implantation, the nitrogen ion is subjected to vacuum or inert gas protection or vacuum plasma high-temperature annealing. And the dosage of the annealed nitrogen implanted diamond is again 0.25 multiplied by 10 according to the energy required by the nickel ion implantation with the same depth as the nitrogen ion implantation¹⁵cm^-2To 1.25X 10¹⁶cm^-2(or lower) nickel ion implantation. Then, the diamond is subjected to vacuum or inert gas protection or vacuum plasma high-temperature annealing again, and the nitrogen atom migration and the formation of the NE8 composite diamond color center are realized while the diamond crystal lattice is recovered.

The technical scheme of the invention is as follows:

a method for preparing the composite color center of diamond N-Ni by ion implantation features that after the N ions with a particular dosage are implanted and the radiation damage is repaired by high-temp annealing, the Ni ions with the same depth and dosage as 1/4 (or less than) are implanted, and then high-temp annealing is performed again to accurately prepare the composite color center of NE 8N-Ni.

Step 1: grinding and polishing of diamonds

In order to meet the requirements of application and test of electronic devices or photoelectric devices, high-quality single crystal diamond is firstly precisely polished, and the surface roughness of the polished single crystal diamond is less than 1 nm.

Step 2: acid washing and pretreatment of diamond:

in order to ensure the surface of the single crystal diamond to be smooth and clean and remove metal impurities, hydrocarbon, graphite and the like which may exist, acid washing and pretreatment of the diamond are needed.

And step 3: injecting nitrogen ions into the diamond;

and 4, step 4: annealing the diamond after nitrogen ion implantation;

and 5: injecting nickel ions after annealing;

step 6: and (5) annealing the diamond after the secondary ion implantation.

Further, the precision polishing step in step 1 is: and pre-polishing the diamond powder with the granularity of 40 to 20 for 24 to 48 hours. The diamond powder was then changed to a particle size of 10 and 2.5 in that order and the above procedure was repeated. Then placing on a precision diamond polishing disk, and respectively carrying out 20-80 hours, 40-160 hours and 80-200 hours under the conditions of the rotating speed of 40 revolutions per minute, 80 revolutions per minute and 120 revolutions per minute.

Further, the step 2 of acid washing and pretreatment of the diamond comprises the following steps:

after polishing, the diamond samples were placed in HCl: h₂SO₄1:5, boiling the mixed solution for 45 minutes to 1 hour, and then washing with deionized water; then the mixture is sequentially placed in acetone solution and absolute ethyl alcohol for ultrasonic cleaning for 10-15 minutes respectively, and then is dried.

Further, the step of nitrogen ion implantation of the diamond in the step 3 is

1) In order to ensure that the average spacing between nitrogen atoms is kept within 2nm after nitrogen ions are implanted into the diamond, the implantation dosage of the nitrogen atoms is higher than 1 x 10¹⁵cm^-2。

2) A large amount of diamond lattice damage may occur due to the ion implantation process. This damage can be recovered by high temperature heat treatment. However, when the concentration of vacancies generated by damage is above a certain upper limit (vacancy concentration 1X 10)²²vac/cm³) This will then lead to irreversible damage, which makes the diamond lattice unrecoverable. Therefore, the implantation dosage of nitrogen atom needs to be lower than 5X 10¹⁶cm^-2。

3) In order to avoid the channel effect in a specific crystal direction in the process of ion implantation into the diamond and influence the accuracy of the ion implantation depth, the implantation angle is adjusted to form an included angle of 7 degrees on the surface of the diamond.

Further, the annealing treatment of the diamond after the nitrogen ion implantation in the step 4 comprises the following steps:

1) and annealing heat treatment is adopted to eliminate diamond lattice damage caused by ion implantation. In order to ensure that the diamond is not oxidized to form graphite in the heat treatment process, the injected diamond is subjected to high-temperature annealing treatment by adopting vacuum or inert gas protection or vacuum plasma.

2) The annealing temperature is 800 ℃, 1000 ℃ and 1200 ℃ for 1 to 2 hours respectively to ensure that the irradiation-generated vacancies have enough energy and time to move, merge and eliminate.

Further, the step 5 of implanting the annealed nickel ions comprises the following steps:

1) the energy required for implantation is different due to the different radii of the two atoms. To ensure that the nitrogen atoms and nickel atoms are polymerized, the nitrogen atoms and nickel atoms are implanted at the same depth.

2) Since NE8 color center is composed of 4 nitrogen atoms and one nickel atom, to ensure the formation of NE8 composite color center, the implantation dose of nickel atoms is 1/4 (or less than 1/4) of the dose of nitrogen atoms.

3) In order to avoid the channel effect in the specific crystal direction during the process of ion implantation into the diamond and influence the accuracy of the ion implantation depth, the implantation angle is adjusted to form an included angle of 7 degrees on the surface of the diamond.

Further, the annealing treatment step of the diamond after the secondary ion implantation in the step 6 is as follows:

1) and vacuum or inert gas protection or vacuum plasma high-temperature annealing treatment is adopted, so that the diamond is ensured to realize lattice recovery in the heat treatment process and is not oxidized to form graphite.

2) The annealing temperature is 800 ℃, 1000 ℃ and 1200 ℃ for 1 to 2 hours respectively to ensure that the irradiation-generated vacancies have enough energy and time to move, merge and eliminate.

3) The temperature is then increased to 1400 ℃ for 1 to 2 hours to effect dissociation of the nitrogen vacancies and movement of the nitrogen ions.

4) The temperature is then raised to 1600 to 2000 ℃ for 0.5 to 1 hour to effect mobile polymerization of the nitrogen atoms and formation of NE8 complex color centers.

The key of the implementation process of the invention is as follows:

(1) in the surface treatment process of the single crystal diamond, diamond powder with different grain diameters and proper polishing time are used for precisely polishing the growth surface of the diamond, so that the diamond is extremely smooth and clean, and graphite phases and unevenness are eliminated. In the process of realizing surface polishing, the surface of the diamond substrate can be precisely planarized by adopting a mechanical chemical polishing method, a plasma auxiliary method or a composite polishing method and the like so as to achieve the surface roughness less than 1 nm.

(2) Performing a first nitrogen ion implantation on the diamond, wherein the implantation dosage is ensured to be higher than 1 × 10¹⁵cm^-2Less than 5X 10¹⁶cm^-2In a range that avoids irreversible structural damage from excessively high radiation doses while ensuring that the mean nitrogen atom spacing is sufficiently close. At the same time, the ion implantation direction should be kept at an angle of 7 ° to the diamond surface to avoid channeling.

(3) After nitrogen ion implantation, vacuum or inert gas protection or vacuum plasma high-temperature annealing treatment is adopted, and oxidation reaction of diamond at an over-high temperature is avoided to form graphite. Meanwhile, the annealing temperature is 800 ℃, 1000 ℃ and 1200 ℃ which are respectively kept for 1 to 2 hours, so that the irradiation-generated vacancies have enough energy and time to move, combine and eliminate.

(4) The second step of nickel ion implantation on the diamond not only keeps the implantation angle of 7 degrees, but also more importantly, the implantation energy of the second step of nickel ion implantation ensures that the implanted nickel ion and the nitrogen ion have the same implantation depth. In addition, the implantation dose should be 1/4 or less than 1/4 of the implantation dose of nitrogen ions.

(5) The second annealing heat treatment still adopts vacuum or inert gas annealing or vacuum plasma high-temperature treatment to ensure that diamond graphitization does not occur. The annealing temperature is 800 ℃, 1000 ℃ and 1200 ℃ for 1 to 2 hours respectively to ensure that the irradiation-generated vacancies have enough energy and time to move, merge and eliminate. The temperature is then increased to 1400 ℃ for 1 to 2 hours to effect dissociation of the nitrogen vacancies and movement of the nitrogen ions. The temperature is then raised to 1600 to 2000 ℃ for 0.5 to 1 hour to effect mobile polymerization of the nitrogen atoms and formation of NE8 complex color centers.

Compared with the prior art, the invention has the beneficial effects that:

the invention realizes the preparation of the nitrogen-nickel composite color center of the diamond NE8 by an ion implantation method. The NE8 color center has a plurality of excellent photoelectric characteristics, so that the NE8 color center has a great prospect in the application field of quantum technology, and especially the single photon emission characteristic of the near infrared band is also in the band where the mature optical fiber communication is located at present. However, human precision preparation and handleability are still key factors limiting their application. Although many studies and techniques have been made to grow the NE8 color center-containing diamond by introducing nickel catalyst during the synthesis of diamond, such as high temperature and high pressure, or by introducing nitrogen gas simultaneously through a chemical vapor deposition process under the condition of nickel as a nucleation seed. However, the nitrogen-nickel mixed color center obtained by the prior art method has the problems of random distribution and low density. Although ion implantation techniques have also been used to prepare NE8, the methods reported so far all suffer from certain design drawbacks. The invention realizes the preparation of the nitrogen-nickel mixed color center of the diamond NE8 by an ion implantation method by combining a theoretical mechanism, calculation and design of a preparation process. More importantly, the method not only can realize accurate control of doping atoms through ion implantation, but also can reserve space for preparing related photoelectric devices in the future based on the advantage that the ion implantation is only distributed on the local part of the diamond, and meanwhile, the method can also be used as a reference for realizing the preparation of a single photon source.

Drawings

FIG. 1 is a graph showing the relationship between the dose with a peak concentration profile depth of 75nm for nitrogen and nickel ion implantation and the corresponding concentration of damage-causing vacancies.

FIG. 2 is a graph of annealing temperature versus barrier to atomic movement in accordance with the present invention.

Detailed Description

The technical scheme of the invention is further explained by combining the specific embodiment

The polished single crystal diamond is ground to a surface roughness of less than 1nm and subjected to cleaning pretreatment. And then, calculating by Monte Carlo to obtain: for example, nitrogen ion implantation at 60keV energy and nickel ion implantation at 170keV energy both have a peak concentration at a shallow surface of 75nm, as shown in FIG. 1. And the damage vacancies produced do not reach a recoverable concentration limit. Fig. 2 shows the relationship between the high-temperature annealing temperature after ion implantation and the corresponding barrier energy.