KR102548005B1 - Method for improving single photon purity of quantum light source - Google Patents

Abstract

The present invention relates to a method for improving single photon purity of a quantum light source, and one aspect of the present invention includes irradiating an ion beam to a peripheral light source of a quantum light source using a focused-ion beam, Provided is a method for improving single photon purity of a quantum light source, wherein the ambient light source is quenched.

Description

Method for improving single photon purity of quantum light source {METHOD FOR IMPROVING SINGLE PHOTON PURITY OF QUANTUM LIGHT SOURCE}

The present invention relates to a method for improving single photon purity of a quantum light source, and more particularly, to a method for implementing a high-purity quantum light source using a focused-ion beam.

Recently, as quantum information technology represented by quantum communication, quantum sensors, and quantum computers develops rapidly, the development of quantum light sources, which are essential elements of quantum information technology, is receiving a lot of attention.

A quantum light source emits a single photon through an atom or molecule with a discrete electronic energy structure and a structure in various solids. Technologies for solid-based quantum light sources include technologies using defects in various solid materials such as diamond or SiC, and technologies using semiconductor quantum dots.

Among them, quantum light sources based on solid materials, such as semiconductor quantum dots or defect structures in solids, have high promise due to their bright brightness and scalability in combination with optical structures and electronic engineering structures.

However, such a quantum light source has a problem in that unintentional light emission from nearby light sources acts as background noise, lowering the signal-to-noise ratio, reducing single-photon purity, and causing a phase shift of the quantum light source.

In order to solve this problem, methods of covering or etching the surrounding light sources with metal have been developed, but these methods have problems in destroying the structure of the surrounding light sources or reducing the brightness of the quantum light sources.

The above background art is possessed or acquired by the inventor in the process of deriving the disclosure of the present application, and cannot necessarily be said to be known art disclosed to the general public prior to the present application.

The present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a quantum light source capable of improving the purity of single photons without changing the luminous intensity of the quantum light source without structural deformation around the quantum light source. It is to provide a method for improving single photon purity.

However, the problem to be solved by the present invention is not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

One aspect of the present invention includes irradiating an ion beam to an ambient light source of a quantum light source using a focused-ion beam, wherein the ambient light source is quenched by the ion beam, and single photon purity of the quantum light source is improved. provides a way

According to an embodiment, the ion source of the focused-ion beam includes helium (He), gold (Au), silicon (Si), gallium (Ga), iridium (Ir), xenon (Xe), chromium (Cr), It may include one or more selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), germanium (Ge), indium (In), tin (Sn), and lead (Pb).

According to one embodiment, the quantum light source is selected from the group consisting of a quantum dot, a quantum well, a quantum island, a quantum disk, and a quantum wire It may be emitted from a quantum structure, including one or more quantum structures.

According to one embodiment, the quantum structure may include a pyramid structure in which quantum dots are located at vertices.

According to one embodiment, the quantum structure is an element semiconductor, a molecular light emitting body, an organic light emitting body, a compound semiconductor, a perovskite material, a two-dimensional transition metal chalcogen compound, h-BN (Hexagonal Boron Nitride), h-BCN ( hexagonal boron-carbon-nitrogen), fluorographene, graphene oxide, and at least one selected from the group consisting of carbon nanotubes, wherein the element semiconductor includes a group IV element semiconductor; or an n-type or p-type semiconductor thereof, wherein the compound semiconductor includes a II-VI group compound semiconductor; Group III-V compound semiconductor; Group IV-VI compound semiconductor; Group IV compound semiconductor; These n-type or p-type semiconductors; may include.

According to one embodiment, the quantum structure includes one or more selected from the group consisting of InN, InGaN, InAlN, GaN, AlGaN, InAs, InGaAs, InAlAs, InGaAsP, InAsP, GaAs, AlGaAs, InSb, and InGaSb. can

According to one embodiment, the quantum structure may include quantum dots formed by a Stranski-Krastanow (S-K) growth method.

According to one embodiment, the ion beam may be irradiated in a donut shape.

According to an embodiment, a crystal structure defect may be induced in a region emitting the ambient light source by adjusting an irradiation amount and an irradiation current value of the ion beam.

An irradiation amount of the ion beam may be 1E5 ions/cm ² to 1E20 ions/cm ² , and an irradiation current value of the ion beam may be 0.01 pA to 100 nA.

Another aspect of the present invention includes a quantum structure that emits a quantum light source, and irradiates an ion beam to the ambient light source of the quantum light source using a coupled-ion beam to quench the ambient light source. Provides an optical device .

According to one embodiment, the single photon purity of the quantum light source may be 0.5 or more.

The method for improving the single-photon purity of a quantum light source according to the present invention uses a focused-ion beam to positionally quench unwanted light sources around the quantum light source, thereby making single-photon pure light without structural deformation or change in luminous intensity of the quantum light source. There is an effect that can improve the degree.

In addition, since only the ion beam is irradiated to the surrounding light sources using the focused-ion beam, the process is very simple compared to existing known methods.

Furthermore, when using an electrically driven quantum dot-based single-photon light source, as a much wider area is excited compared to the optical excitation method, it is possible to improve the relatively large background noise generated from surrounding light sources, and to improve the S-K quantum dot-based single-photon light source When used in an optical integrated circuit, there is an effect of improving the problem of surrounding quantum dots acting as background noise.

1 is a schematic diagram of a technique for quenching unwanted light emission using a focused-ion beam.
2 shows SEM images, CL images, and X SCAN measurement results when a linear focused-ion beam is irradiated to a planar quantum well.
3 shows SEM images, CL images, and X SCAN measurement results when a donut-shaped focused ion beam is irradiated to a planar quantum well.
4 is an SEM image and a CL image when a donut-shaped focused ion beam is irradiated to a quantum well on a side surface of a pyramid structure.
5 is a spectrum before and after irradiating a donut-shaped focused ion beam to a quantum well around a quantum dot located at a vertex of a pyramid structure.
6 is a result of measuring emission signal intensity before and after irradiating a donut-shaped focused ion beam to a quantum well around a quantum dot located at a vertex of a pyramid structure.
7 is a measurement result of single photon purity before and after irradiating a donut-shaped focused ion beam to a quantum well around a quantum dot located at a vertex of a pyramid structure.
8 is a CL image of Stranski-Krastanov (SK) quantum dots after irradiation of a donut-shaped focused-ion beam and spectra before and after irradiation of a focused-ion beam.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, since various changes can be made to the embodiments, the scope of the patent application is not limited or limited by these embodiments. It should be understood that all changes, equivalents or substitutes to the embodiments are included within the scope of rights.

Terms used in the examples are used only for descriptive purposes and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiment belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

In addition, in the description with reference to the accompanying drawings, the same reference numerals are given to the same components regardless of reference numerals, and overlapping descriptions thereof will be omitted. In describing the embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description will be omitted.

In addition, in describing the components of the embodiment, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, order, or order of the corresponding component is not limited by the term. When an element is described as being “connected,” “coupled to,” or “connected” to another element, that element may be directly connected or connected to the other element, but there may be another element between the elements. It should be understood that may be "connected", "coupled" or "connected".

Components included in one embodiment and components having common functions will be described using the same names in other embodiments. Unless stated to the contrary, descriptions described in one embodiment may be applied to other embodiments, and detailed descriptions will be omitted to the extent of overlap.

One aspect of the present invention includes irradiating an ion beam to an ambient light source of a quantum light source using a focused-ion beam, wherein the ambient light source is quenched by the ion beam, and single photon purity of the quantum light source is improved. provides a way

The method for improving the single-photon purity of a quantum light source according to the present invention uses a focused-ion beam to positionally quench undesirable light sources around the quantum light source, thereby eliminating structural deformation and changing the luminous intensity of the quantum light source. It has a feature that can improve the degree, and since it only needs to irradiate the ion beam to the surrounding light sources using the focused-ion beam, the process is very simple compared to the existing known methods.

The quantum light source may mean a photon emitted by a nano-sized material in a semiconductor while having a discontinuous electronic energy structure, and the ambient light source is an unnecessary light source other than the quantum light source, that is, background noise. It may mean a light source that generates.

The focused-ion beam generally includes a gun that generates a high-energy ion beam, a column that adjusts the size and energy of the emitted ion beam, and a stage that can move or tilt by fixing a sample to be processed ( stage). Ions emitted from the gun have very high kinetic energy and are thousands of times heavier than electrons, so unlike electron beams, when they collide with a sample, they can eject atoms that previously constituted the sample. In addition, since the ion beam can be focused to a size of tens of nanometers or less while passing through a column, nanometer-level processing can be realized by irradiating the ion beam only to a desired portion on the sample and removing materials from that portion.

The method for improving the single-photon purity of a quantum light source according to the present invention can achieve high purity of a quantum light source without structural deformation or change in luminous intensity by selectively quenching ambient light sources other than quantum light sources on a nanoscale using a focused-ion beam. can

The single photon purity is the most important indicator of a single photon light source and represents the distribution of the number of photons.

The single photon purity may be defined by Equation 1 below.

[Equation 1]

Single photon purity = 1 - g ⁽²⁾ (0)

Here, g ⁽²⁾ (0) means the correlation value of photons obtained through the Hanbury Brown and Twiss experiment, and the closer to 0, the higher the single photon purity.

According to an embodiment, the ion source of the focused-ion beam includes helium (He), gold (Au), silicon (Si), gallium (Ga), iridium (Ir), xenon (Xe), chromium (Cr), It may include one or more selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), germanium (Ge), indium (In), tin (Sn), and lead (Pb).

The ion source of the focused-ion beam includes helium (He), gold (Au), silicon (Si), gallium (Ga), iridium (Ir), xenon (Xe), chromium (Cr), iron (Fe), and cobalt. It may include one or more ions selected from the group consisting of (Co), nickel (Ni), germanium (Ge), indium (In), tin (Sn), and lead (Pb).

The helium (He) has a very light mass and has the advantage of being able to be processed very precisely and sharply, and may be suitable for quenching ambient light sources when quantum light sources are integrated, such as optical integrated circuits.

That is, since the helium (He) ions have the smallest mass and can be quenched in the most precise area under the same irradiation conditions, unwanted light emitting areas can be precisely quenched.

Since the melting point of gallium (Ga) is near room temperature, it is characterized in that it can be easily melted even when a small amount of current flows. That is, since the bonding energy between atoms is very low, it is easier than other materials to emit ions from a source when a voltage is applied.

According to one embodiment, the quantum light source is selected from the group consisting of a quantum dot, a quantum well, a quantum island, a quantum disk, and a quantum wire It may be emitted from a quantum structure, including one or more quantum structures.

The quantum dot is a nano-sized crystal structure, and the bandgap of the quantum dot exhibits a quantum confinement effect in which the movement of both electrons and holes, which are two carriers in a semiconductor, is restricted in three dimensions.

The quantum light source emitted from the quantum dots has the advantage of having bright brightness, and when unwanted ambient light sources are quenched by the method according to the present invention, the purity of the quantum light source can be effectively improved by removing background noise while maintaining the brightness. .

According to one embodiment, the quantum structure may include a three-dimensional structure, and the three-dimensional structure may include a hexagonal pyramid, a triangular pyramid, a hexagonal pyramid having a top hexagonal pyramid, or an inverted pyramid of the hexagonal pyramid. can

According to one embodiment, the quantum structure may include a pyramid structure in which quantum dots are located at vertices.

The pyramid structure may refer to a structure having quantum dots located at vertices and having a quantum well structure on a side surface.

When unwanted ambient light sources are quenched by the method according to the present invention in the quantum wells around the quantum dots located at the vertices of the pyramid structure, the background noise is greatly reduced without a significant change in the luminous intensity signal of the quantum light source, thereby reducing the signal-to-noise ratio (signal- to-noise ratio, SNR, S/N) can be effectively improved.

According to one embodiment, the pyramid structure may have indium gallium nitrogen (InGaN) quantum dots located at vertices.

According to one embodiment, the quantum structure is an element semiconductor, a molecular light emitting body, an organic light emitting body, a compound semiconductor, a perovskite material, a two-dimensional transition metal chalcogen compound, h-BN (Hexagonal Boron Nitride), h-BCN ( hexagonal boron-carbon-nitrogen), fluorographene, graphene oxide, and at least one selected from the group consisting of carbon nanotubes, wherein the element semiconductor is a group IV element semiconductor; These include an n-type or p-type semiconductor; the compound semiconductor includes a II-VI group compound semiconductor; Group III-V compound semiconductor; Group IV-VI compound semiconductor; Group IV compound semiconductor; These n-type or p-type semiconductors; may include.

For example, the II-VI compound semiconductor is CdO, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdOS, CdOSe, CdOTe, CdSSe, CdSTe, CdSeTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, CdHgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgST e, HgZnSeS, HgZnSeTe or HgZnSTe, but It is not limited.

The group III-V compound semiconductor is BN, BP, AlP, BAs, GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, BNP, BNAs, BPAs, GaNP, GaNAs , GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, AlGaN, InGaN, InNP, InNAs, InNSb, InPAs, InPSb, BAlGaN, BAlInN, BGaInN, GaAlNP, GaAlNAs, InAlGaN, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP , GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs or InAlPSb, but not limited thereto.

The group IV-VI compound semiconductor may include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe or SnPbSTe, It is not limited thereto.

The group IV compound semiconductor may include Si, Ge, SiC, SiGe or SiCGe, but is not limited thereto.

In addition, the n-type semiconductor is an inorganic compound semiconductor doped with an n-type impurity, and the n-type impurity includes elements such as N, P, As, Ge, Si, Cu, Ag, Au, Sb, and Bi. can do. The p-type semiconductor is an inorganic compound semiconductor doped with a p-type impurity, and the p-type impurity may include elements such as Mg, B, In, Ga, Al, and Tl.

According to one embodiment, the quantum structure includes one or more selected from the group consisting of InN, InGaN, InAlN, GaN, AlGaN, InAs, InGaAs, InAlAs, InGaAsP, InAsP, GaAs, AlGaAs, InSb, and InGaSb. can

According to one embodiment, the quantum structure may include a point defect inside the semiconductor. For example, the point defect inside the semiconductor may be a point defect inside SiC or a point defect inside GaN.

According to one embodiment, the quantum structure is formed using one or more methods selected from the group consisting of metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and hydride vapor phase epitaxy (HVPE). can

According to one embodiment, the quantum structure may include quantum dots formed by a Stranski-Krastanow (S-K) growth method.

In addition, the quantum structure may include quantum dots formed by a position-controlled growth method or chemically synthesized quantum dots.

The Stranski-Krastanov growth method is generally possible with growth equipment such as MBE (Molecular Beam Epitaxy) or MOCVD (metal-organic chemical vapor deposition), and a material with a small band gap grows on a material with a large band gap while lattice This is how small islands of nanometer size are naturally created due to constant differences. Due to the small size of quantum dots, electrons and holes have discrete energy levels, and the generation of excitons (electron-hole pairs) can be controlled under weak excitation. When these electron-hole pairs undergo luminescent recombination, single photons are emitted.

The quantum light source emitted from the quantum dots formed by the Stranski-Krastanow (S-K) growth method is integrated into an optical integrated circuit and used. At this time, there is a problem that the surrounding quantum dots may act as background noise.

The single photon purity enhancement method according to the present invention can suppress peripheral signals without destroying the structure of the optical integrated circuit, unlike conventional methods that cannot be applied because the structure of the optical integrated circuit can be destroyed.

According to one embodiment, the quantum light source according to the present invention may be an organic semiconductor-based quantum light source as well as an inorganic semiconductor.

According to an embodiment, the ion beam may be irradiated in various shapes according to the shape of an ambient light source to be removed.

For example, it may be a line shape, a donut shape, a circle shape, a triangle, a rectangle, a hexagon, etc., but is not limited thereto.

According to one embodiment, the ion beam may be irradiated in a donut shape.

When the ion beam is irradiated in a donut shape, the ambient light source can be effectively quenched with high resolution by adjusting the diameter of the inner hole through which the quantum light source is emitted.

According to an embodiment, a crystal structure defect may be induced in a region emitting the ambient light source by adjusting an irradiation amount and an irradiation current value of the ion beam.

That is, by adjusting the irradiation amount and the irradiation current value of the ion beam, only crystal structure defects may be induced without structural deformation of the region emitting the ambient light source.

An irradiation amount and an irradiation current value of the ion beam may be adjusted according to physical and chemical properties of an area to which the ion beam is irradiated.

According to an embodiment, an irradiation amount of the ion beam may be 1E5 ions/cm ² to 1E20 ions/cm ² , and a current value of the ion beam may be 0.01 pA to 100 nA.

Another aspect of the present invention includes a quantum structure that emits a quantum light source, and irradiates an ion beam to the ambient light source of the quantum light source using a coupled-ion beam to quench the ambient light source. Provides an optical device .

According to one embodiment, the single photon purity of the quantum light source may be 0.5 or more.

According to one embodiment, the single photon purity of the quantum light source may be 0.6 or more.

The single photon purity is the most important indicator of a single photon light source and represents the distribution of the number of photons.

The single photon purity may be defined by Equation 1 below.

[Equation 1]

Single photon purity = 1 - g ⁽²⁾ (0)

Here, g ⁽²⁾ (0) means the correlation value of photons obtained through the Hanbury Brown and Twiss experiment, and the closer to 0, the higher the single photon purity.

Another aspect of the present invention includes a quantum structure that emits a quantum light source, and irradiates an ion beam to the ambient light source of the quantum light source using a coupled-ion beam to quench the ambient light source. Provides an optical device .

The optical device includes a down conversion device that absorbs light of high energy injected from the outside and converts it into light of low energy by a quantum structure, or an electroluminescent device that converts the current injected from the outside into light. can do.

According to one embodiment, the optical element may be an integrated optical element, which is an element that performs arithmetic processing with an optical signal instead of an electronic signal.

Another aspect of the present invention, including the quantum structure, provides a component for quantum information communication, which is obtained by quenching the ambient light source of the quantum light source emitted by the quantum structure through a focused-ion beam.

The component for quantum information communication may include one or more selected from the group consisting of components for a quantum key distribution system, components for a quantum measurement system, components for quantum communication, and components for a quantum computer.

A quantum light source can implement 'Qbit', a basic unit of quantum information processing, such as electron spin or superconducting current. A qubit is a unit that expresses information by overlapping or intertwining 1 and 0 in a quantum state. It is a concept that is more advanced than the bit, which is a unit of conventional information processing that expresses information with 1 and 1.

For example, when a quantum light source is applied to quantum cryptographic communication, the high purity of the quantum light source increases the security of quantum cryptographic communication and can minimize the error rate of quantum information processing. That is, the high-purity quantum light source according to the present invention can improve its performance by being applied to quantum key distribution, quantum measurement, quantum communication, or quantum computing.

Here, the quantum key distribution refers to a method in which two communicators exchange codes in an optical fiber or free space using a single photon. If a hacker intercepts these photons, it can be confirmed that the password is leaked by the observer effect of the quantum role, that is, the property of quantum mechanics that cannot be directly measured without changing the state. Quantum key distribution is a method using physical characteristics rather than algorithms, and the generation of photons is a very important factor that determines the performance of quantum key distribution systems.

In addition, the quantum measurement refers to a technology for detecting extremely small signals that are difficult to detect by classical methods, and can be applied to gravitational wave measurement, etc., and quantum computing enables ultra-high-speed and large-capacity calculations using quantum physical properties. It is a next-generation information and communication technology that uses quantum properties such as superposition and entanglement to simultaneously process multiple pieces of information.

Hereinafter, the present invention will be described in more detail by examples and comparative examples.

However, the following examples are only for illustrating the present invention, and the content of the present invention is not limited to the following examples.

<Example 1> Measurement of extinction and properties of a planar quantum well using a focused-ion beam

In order to confirm the extinction effect of the focused-ion beam, the ion beam was projected in the form of a line on the planar InGaN quantum well structure.

In addition, in order to effectively suppress the light emission of the light sources around the quantum dots, the ion beam was fired in a donut shape, and to confirm this, the ion beam was irradiated while changing the inner radius condition of the donut shape ion beam.

A helium ion microscope was used for regioselective extinction during testing.

After ion beam irradiation, a structural change was confirmed using a scanning electron microscope (SEM), and a luminescence change was confirmed through cathodoluminescence (CL) measurement.

1 is a schematic diagram of a technique for quenching unwanted light emission using a focused-ion beam.

Referring to FIG. 1 , a series of processes in which helium ions emitted from a tungsten tip of a focused-ion beam pass through an electrode and an aperture and are projected to a target light source can be understood.

2 shows SEM images, CL images, and X SCAN measurement results when a linear focused-ion beam is irradiated to a planar quantum well.

Referring to FIG. 2 , it can be confirmed from the SEM image that no structural deformation occurs when the linear ion beam is irradiated, and the CL image confirms that the light emission disappears linearly. In addition, the full width at half maximum of extinction was measured to be 270 nm.

3 shows SEM images, CL images, and X SCAN measurement results when a donut-shaped focused ion beam is irradiated to a planar quantum well.

Referring to FIG. 3 , it can be confirmed through the SEM image that no structural change is shown when the donut-shaped ion beam is irradiated, and it can be seen from the CL image that the luminescence disappears in the donut shape.

In addition, in the CL results, it was confirmed that a half-width of 420 nm was obtained when the emission intensity of the central portion was maintained, and that the half-width of the emission intensity of the central portion could be reduced to 120 nm, considering the decrease in emission intensity to some extent.

<Example 2> Measurement of quenching and characteristics of quantum wells on the side of a pyramid structure using a focused-ion beam

Ion beams were shot in a donut shape to eliminate the emission of quantum wells on the sides of the pyramid structure. Scanning electron microscopy and CL results were obtained while gradually decreasing the inner diameter of the donut-shaped ion beam.

In addition, after the extinction method was applied to the quantum wells around the quantum dots at the vertices of the pyramid structure, the before and after spectra and single photon purity were compared through photometry.

The single photon purity can be obtained by measuring the second-order correlation through the Hanbury Brown and Twiss (HBT) experiment, and the single photon purity is defined as 1-g ⁽²⁾ (0).

4 is an SEM image and a CL image when a donut-shaped focused ion beam is irradiated to a quantum well on a side surface of a pyramid structure.

Referring to FIG. 4 , although there is no change in the shape of the pyramid structure through the SEM image, it can be seen through the CL image that the size of the remaining light emitting region is reduced according to the inner diameter of the donut-shaped ion beam.

5 is a spectrum before and after irradiating a donut-shaped focused ion beam to a quantum well around a quantum dot located at a vertex of a pyramid structure.

6 is a result of measuring emission signal intensity before and after irradiating a donut-shaped focused ion beam to a quantum well around a quantum dot located at a vertex of a pyramid structure.

5 and 6, after irradiation with the ion beam, the light emitting signal of the quantum dot, which is a sharp protruding peak, is not significantly different from before the ion beam irradiation, but the size of background noise, which is a widely spread part below the peak, is greatly reduced. there is.

7 is a measurement result of single photon purity before and after irradiating a donut-shaped focused ion beam to a quantum well around a quantum dot located at a vertex of a pyramid structure.

Referring to FIG. 7 , the single photon purity before extinction was 0.27, but as a result of removing background noise through extinction and additionally using a linear polarizer, it can be confirmed that the single photon purity increased to 0.67.

<Example 3> Measurement of extinction and properties around Stranski-Krastanov (S-K) quantum dots using a focused-ion beam

In S-K quantum dots, since many quantum dots are concentrated in a narrow area, other quantum dots in addition to the quantum dots used for single-photon signals act as unintended ambient light sources. Therefore, in order to find conditions for quenching other quantum dots around it, the luminescence was measured while decreasing the inner diameter of the donut-shaped ion beam.

8 is a CL image of Stranski-Krastanov (S-K) quantum dots after irradiation of a donut-shaped focused-ion beam and a spectrum before and after irradiation of a focused-ion beam.

Referring to FIG. 8 , it can be seen that in a state in which extinction is not applied, a spectrum is widely spread while a large number of quantum dots simultaneously emit light.

In addition, as a result of applying extinction while reducing the inner diameter of the ion beam, sharp emission signals of quantum dots were obtained when the inner radius was 1 μm, and the single photon purity of the quantum dots obtained at this time was 0.72.

As described above, although the embodiments have been described with limited drawings, those skilled in the art can apply various technical modifications and variations based on the above. For example, the described techniques may be performed in an order different from the method described, and/or components of the described system, structure, device, circuit, etc. may be combined or combined in a different form than the method described, or other components may be used. Or even if it is replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents of the claims are within the scope of the following claims.

Claims (11)

A step of irradiating an ion beam to a peripheral light source of a quantum light source using a focused-ion beam;
The ambient light source is quenched by the ion beam.
A method for improving the single photon purity of a quantum light source.
According to claim 1,
The ion source of the focused-ion beam,
Helium (He), Gold (Au), Silicon (Si), Gallium (Ga), Iridium (Ir), Xenon (Xe), Chromium (Cr), Iron (Fe), Cobalt (Co), Nickel (Ni), Which includes at least one selected from the group consisting of germanium (Ge), indium (In), tin (Sn) and lead (Pb),
A method for improving the single photon purity of a quantum light source.
According to claim 1,
The quantum light source,
From a quantum structure, including one or more quantum structures selected from the group consisting of a quantum dot, a quantum well, a quantum island, a quantum disk, and a quantum wire that is emitted,
A method for improving the single photon purity of a quantum light source.
According to claim 3,
The quantum structure,
To include a pyramid structure in which quantum dots are located at the vertices,
A method for improving the single photon purity of a quantum light source.
According to claim 3,
The quantum structure,
Elemental semiconductor, molecular light-emitting body, organic light-emitting body, compound semiconductor, perovskite material, two-dimensional transition metal chalcogen compound, h-BN (hexagonal boron nitride), h-BCN (hexagonal boron-carbon-nitrogen), fluorograph It includes at least one selected from the group consisting of fluorographene, graphene oxide, and carbon nanotubes,
The elemental semiconductor may include a group IV elemental semiconductor; Or their n-type or p-type semiconductor; to include,
The compound semiconductor may include a II-VI group compound semiconductor; Group III-V compound semiconductor; Group IV-VI compound semiconductor; Group IV compound semiconductor; Those comprising n-type or p-type semiconductors;
A method for improving the single photon purity of a quantum light source.
According to claim 3,
The quantum structure,
Including quantum dots formed by the Stranski-Krastanow (SK) growth method,
A method for improving the single photon purity of a quantum light source.
According to claim 1,
The ion beam,
which is irradiated in a donut shape,
A method for improving the single photon purity of a quantum light source.
According to claim 1,
Inducing a crystal structure defect in a region emitting the ambient light source by adjusting an irradiation amount and an irradiation current value of the ion beam;
A method for improving the single photon purity of a quantum light source.
According to claim 8,
The irradiation amount of the ion beam is 1E5 ions/cm ² to 1E20 ions/cm ² ,
The irradiation current value of the ion beam is 0.01 pA to 100 nA,
A method for improving the single photon purity of a quantum light source.
Including a quantum structure that emits a quantum light source,
An ion beam is irradiated to the ambient light source of the quantum light source using a connected-ion beam to quench the ambient light source,
optical element.
According to claim 10,
The single photon purity of the quantum light source is 0.5 or more,
The single photon purity is defined by the following formula 1,
Optical element:
[Equation 1]
Single photon purity = 1 - g ⁽²⁾ (0)
The above g ⁽²⁾ (0) means the photon correlation value obtained through the Hanbury Brown and Twiss experiment.

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