Preparation method of solid-state quantum light source

Abstract

The invention relates to a solid-state quantum light source preparation method which comprises the following steps: S1, preparing a front metal mark: exposing and developing the front of a sample, evaporating metal after developing, and stripping; s2, preparing a back metal mark: exposing and developing the back of the sample treated in the step S1, and evaporating metal and stripping after developing; s3, front quantum dot positioning: performing quantum dot positioning on the sample treated in the step S2 to determine the position of the quantum dot; s4, preparing a micro-column on the front surface: preparing the micro-column on the front surface of the sample treated in the step S3; s5, planarization of the front micro-column: planarization is carried out on the sample processed in the step S4; and S6, preparing a back surface super surface: preparing the super surface on the back surface of the sample treated in the step S5. According to the invention, high brightness, high purity and high coherence are realized, and meanwhile, the metasurface regulates and controls the luminescence of the quantum dots in dimensions including but not limited to phase, polarization and the like, so that a novel solid-state quantum light source with high brightness, high purity, high coherence and strong micro-nano light field regulation and control capability is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano device preparation, and more specifically, to a method for preparing a solid-state quantum light source. Background Art

[0002] Single photon sources are not only important in quantum information processing, quantum secure communication, quantum radar and quantum optical computing, but also have important application value in the fields of trace absorption measurement, ultra-high sensitivity magnetic field measurement, bioluminescence labeling and imaging. Among the many single photon emission generation schemes, single photon sources based on quantum dots have great advantages over other single photon sources in all aspects, such as narrow spectral line width, high oscillator strength, no light fading or flickering, small time jitter, high repetition frequency, emission band covering all bands from ultraviolet to infrared, suitable for electric pumping, etc. Usually, quantum dots emit single photons without directionality, and their spontaneous radiation efficiency in free space is low, resulting in low repetition frequency. Especially for group III nitride semiconductor materials, they have strong spontaneous polarization and piezoelectric polarization fields, which lead to the separation of electron-hole wave functions (i.e., quantum confined Stark effect), which suppresses their spontaneous radiation process and limits the repetition frequency. In most quantum technology applications, single photon sources are required to have a high repetition frequency of more than GHz.

[0003] In order to improve the repetition frequency and emission efficiency of the single-photon source and obtain a high-quality single-photon source, quantum dots can be placed in a microcavity and the Purcell effect can be used, that is, the spontaneous radiation of the quantum emitter in the microcavity can be greatly enhanced compared to the spontaneous radiation in free space, so that the quantum efficiency of single-photon emission can be improved by using the microcavity. For electrically pumped devices, the presence of a microcavity can greatly reduce the operating voltage of electrical injection, thereby improving the stability of the device. Usually, a DBR micro-column cavity or a photonic crystal microcavity is used to obtain a high-quality single-photon source. However, although the DBR micro-column cavity can limit light in the vertical direction and produce a high Purcell factor, it only relies on the reflection of the micro-column side wall interface to limit light in the plane direction, which will produce obvious light leakage losses, forming a photon emission channel of non-resonant wavelengths, resulting in the deterioration of the performance of the single-photon source; the photonic crystal microcavity can limit photons in two or even three dimensions, which can further improve the luminescence performance of quantum dots.

[0004] Among the existing technical solutions, some use the external metasurface as a discrete device to regulate on-chip quantum light sources, with a very low degree of integration; some are made into integrated devices, but lack the cavity enhancement effect and the ability to regulate micro-nano light fields. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art, such as low integration and poor micro-nano light field control capability, and to provide a method for preparing a solid-state quantum light source with high integration and strong micro-nano light field control capability.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for preparing a solid-state quantum light source is provided, comprising the following steps:

[0008] S1. Preparation of front metal mark: Expose and develop the front side of the sample, evaporate metal after development and peel off;

[0009] S2. Preparation of back metal mark: exposing and developing the back of the sample after step S1, and then evaporating the metal and peeling it off after development;

[0010] S3. Positive quantum dot positioning: performing quantum dot positioning on the sample processed in step S2 to determine the position of the quantum dots;

[0011] S4. Preparation of front microcolumns: preparing microcolumns on the front of the sample treated in step S3;

[0012] S5. Flattening the front microcolumn: Flattening the sample after processing in step S4;

[0013] S6. Preparation of back side super surface: Prepare a super surface on the back side of the sample processed in step S5.

[0014] The present invention provides a method for preparing a solid-state quantum light source, wherein the metal markers in steps S1 and S2 are used for positioning the quantum dots in step S3, and the microcolumns in step S4 and the supersurface in step S6 are used for positioning, so as to achieve spatial alignment of the front microcolumns, quantum dots, and the back supersurface. The microcolumns can enhance the luminescence of the quantum dots to achieve high brightness, high purity, and high coherence, while the supersurface regulates the luminescence of the quantum dots in dimensions including but not limited to phase and polarization, so as to achieve a new solid-state quantum light source with high brightness, high purity, high coherence, and strong micro-nano light field regulation capability.

[0015] Preferably, the sample comprises, from bottom to top, a gallium arsenide substrate layer, a lower DBR (distributed Bragg reflector) layer, a quantum dot layer, and an upper DBR layer.

[0016] Preferably, the position where exposure is performed in step S1 and the position where exposure is performed in step S2 are aligned in front and back directions in the sample space.

[0017] Preferably, in step S1 and step S2, the exposure uses PMMA (polymethyl methacrylate) electron beam photoresist with a thickness of 650nm to 750nm, and the exposure parameters include a beam current of 8nA to 12nA, a dose of 600μC / cm 2 ~700μC / cm 2 The development uses MIBK (methyl isobutyl ketone) developer, and the development time is 1min to 2min; the metal used for the evaporation includes gold, and the thickness is 100nm to 600nm; the stripping solution used for the stripping includes trichloroethylene solution or acetone.

[0018] Preferably, in step S3, quantum dot positioning includes exciting the quantum dots in the quantum dot layer to emit light by a high-power laser to determine and record the quantum dot position, where the quantum dot position is the position of the front metal mark in step S1. The metal mark enables the alignment of quantum dots and high-precision preparation.

[0019] Preferably, step S4 includes exposure, etching and stripping; the exposure uses HSQ (Hydrogen Silsesquioxane Polymers) electron beam photoresist, and the exposure parameters include: beam current 4nA-6nA, dose 750μC / cm 2 ~850μC / cm 2 The etching includes etching using an inductively coupled plasma etcher, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 6:10:2, the chamber pressure is 5.5mTorr~6.5mTorr, the radio frequency voltage is 450W~550W, and the degumming includes degumming using a hydrofluoric acid solution.

[0020] Preferably, in step S4, the position exposed in step S4 is aligned with the position of the quantum dot in step S3. The exposure position and the quantum dot position are opposite to each other, thereby achieving alignment between the microcolumn and the quantum dot.

[0021] Preferably, in step S5, planarization includes spin coating a photoresist (SU8 reagent) onto the sample and then curing the sample using an ultraviolet curing lamp.

[0022] Preferably, in step S6, preparing the metasurface includes exposure, etching and degumming; the exposure position is spatially aligned with the quantum dot position in step S3, and the exposure uses HSQ electron beam photoresist, and the exposure parameters include: beam current 0.7nA-0.9nA, dose 900μC / cm 2 ~1100μC / cm 2The etching includes etching using an inductively coupled plasma etcher, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 2:10:1, the chamber pressure is 4.5mTorr~5.5mTorr, and the radio frequency voltage is 90W~110W; the degumming includes degumming using hydrofluoric acid.

[0023] The present invention also provides a solid-state quantum light source, which is prepared using the solid-state quantum light source preparation method described above.

[0024] A solid-state quantum light source of the present invention has front microcolumns, quantum dots and back metasurface aligned in space. The microcolumns can enhance the luminescence of quantum dots to achieve high brightness, high purity and high coherence. At the same time, the metasurface regulates the luminescence of quantum dots in dimensions including but not limited to phase and polarization to achieve a new solid-state quantum light source with high brightness, high purity, high coherence and strong micro-nano light field regulation capabilities.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a method for preparing a solid-state quantum light source, which realizes the spatial alignment of the front microcolumns, quantum dots and the back metasurface. The microcolumns can enhance the luminescence of the quantum dots to achieve high brightness, high purity and high coherence, while the metasurface regulates the luminescence of the quantum dots in dimensions including but not limited to phase and polarization, so as to realize a new solid-state quantum light source with high brightness, high purity, high coherence and strong micro-nano light field regulation capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a process for preparing a solid-state quantum light source according to the present invention;

[0028] Figure 2 A schematic diagram of a preparation process of a solid-state quantum light source preparation method of the present invention;

[0029] Figure 3 A schematic diagram of a microcolumn structure prepared by a method for preparing a solid-state quantum light source of the present invention;

[0030] Figure 4 A schematic diagram of a metasurface structure prepared by a method for preparing a solid-state quantum light source of the present invention.

[0031] Figure 5 This is a diagram of the microcavity enhancement effect of a quantum light source prepared by a solid-state quantum light source preparation method of the present invention.

[0032] Figure 6 It is a schematic diagram of light modulation by a quantum light source metasurface prepared by a solid-state quantum light source preparation method of the present invention.

[0033] Figure 7It is a schematic diagram of light suppression by a quantum light source metasurface prepared by a solid-state quantum light source preparation method of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0035] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] Embodiment 1

[0037] This embodiment is the first embodiment of a method for preparing a solid-state quantum light source. Figure 1 and Figure 2 As shown, the following steps are included:

[0038] S1. Preparation of front metal mark: Expose and develop the front side of the sample, evaporate metal after development and peel off;

[0039] S2. Preparation of back metal mark: exposing and developing the back of the sample after step S1, and then evaporating the metal and peeling it off after development;

[0040] S3. Positive quantum dot positioning: performing quantum dot positioning on the sample processed in step S2 to determine the position of the quantum dots;

[0041] S4. Preparation of front microcolumns: preparing microcolumns on the front of the sample treated in step S3;

[0042] S5. Flattening the front microcolumn: Flattening the sample after processing in step S4;

[0043] S6. Preparation of back side super surface: Prepare a super surface on the back side of the sample processed in step S5.

[0044] In this embodiment, the sample includes, from bottom to top, a gallium arsenide substrate layer, a lower DBR (distributed Bragg reflector) layer, a quantum dot layer, and an upper DBR layer.

[0045] In this embodiment, the position where exposure is performed in step S1 and the position where exposure is performed in step S2 are aligned in the front and back sides in the sample space position.

[0046] In this embodiment, in step S1 and step S2, the exposure uses PMMA (polymethyl methacrylate) electron beam photoresist with a thickness of 650nm to 750nm, and the exposure parameters include a beam current of 8nA to 12nA, a dose of 600μC / cm 2 ~700μC / cm 2 The development uses MIBK (methyl isobutyl ketone) developer, and the development time is 1min to 2min; the metal used for the evaporation includes gold, and the thickness is 100nm to 600nm; the stripping solution used for the stripping includes trichloroethylene solution or acetone.

[0047] In this embodiment, in step S3, quantum dot positioning includes exciting quantum dots in the quantum dot layer to emit light by a high-power laser to determine and record the position of the quantum dots, where the position of the quantum dots is the position of the front metal mark in step S1.

[0048] In this embodiment, step S4 includes exposure, etching and stripping; the exposure uses HSQ (Hydrogen Silsesquioxane Polymers) electron beam photoresist, and the exposure parameters include: beam current 4nA ~ 6nA, dose 750μC / cm 2 ~850μC / cm 2 The etching includes etching using an inductively coupled plasma etcher, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 6:10:2, the chamber pressure is 5.5mTorr~6.5mTorr, the radio frequency voltage is 450W~550W, and the degumming includes degumming using a hydrofluoric acid solution.

[0049] In this embodiment, in step S4, the position exposed in step S4 is aligned with the position of the quantum dots in step S3.

[0050] In this embodiment, in step S5, planarization includes spin coating the SU8 reagent onto the sample and then curing it using an ultraviolet curing lamp.

[0051] In this embodiment, the preparation of the metasurface in step S6 includes exposure, etching and degumming; the exposure position is spatially aligned with the quantum dot position in step S3, and the exposure uses HSQ electron beam photoresist, and the exposure parameters include: beam current 0.7nA-0.9nA, dose 900μC / cm2 ~1100μC / cm 2 The etching includes etching using an inductively coupled plasma etcher, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 2:10:1, the chamber pressure is 4.5mTorr~5.5mTorr, and the radio frequency voltage is 90W~110W; the degumming includes degumming using hydrofluoric acid.

[0052] The present invention provides a method for preparing a solid-state quantum light source, wherein the metal markers in steps S1 and S2 are used for positioning the quantum dots in step S3, and the microcolumns in step S4 and the supersurface in step S6 are used for positioning, so as to achieve spatial alignment of the front microcolumns, quantum dots, and the back supersurface. The microcolumns can enhance the luminescence of the quantum dots to achieve high brightness, high purity, and high coherence, while the supersurface regulates the luminescence of the quantum dots in dimensions including but not limited to phase and polarization, so as to achieve a new solid-state quantum light source with high brightness, high purity, high coherence, and strong micro-nano light field regulation capability.

[0053] Embodiment 2

[0054] This embodiment is a second embodiment of a method for preparing a solid-state quantum light source. This embodiment uses the solid-state quantum dot light source prepared in the first embodiment for testing.

[0055] like Figure 3 and Figure 4 As shown, the micropillars and metasurfaces prepared by the method of the present invention achieve spatial alignment of the front micropillars, quantum dots and the back metasurface.

[0056] like Figure 5 As shown, the fluorescence decay curves of quantum dots (QD) under different environments are shown. The horizontal axis is time delay (nanoseconds) and the vertical axis is intensity.

[0057] The red curve represents the decay of the quantum dot in the microcavity, labeled “QD at resonance”.

[0058] The blue curve represents the decay of quantum dots in bulk material, labeled “QD in bulk”.

[0059] Two time constants are given in the figure:

[0060] τcavity=575psτcavity=575ps: represents the fluorescence lifetime of the quantum dot in the resonant cavity.

[0061] τbulk=1093psτbulk=1093ps: represents the fluorescence lifetime of quantum dots in bulk material.

[0062] The fluorescence lifetime of quantum dots in the microcavity is shorter due to the cavity enhancement effect, indicating that photon emission is faster and the luminescence of quantum dots is enhanced.

[0063] like Figure 6 As shown, the far-field distribution of light emitted by the microcolumn structure is demonstrated, and this emission is modulated by the metasurface. The bright spots in the figure indicate the emission direction and intensity of the light. The bright spots in the figure indicate the emission direction of the light, and two angles are marked: θ=10°, θ=10° and θ=15°, θ=15°. These angles show the offset of the light relative to the central axis. The metasurface modulates the phase of light through its designed structure, thereby changing the propagation direction and focusing characteristics of the light. It can be used to precisely control the emission characteristics of light and improve the performance of optical devices.

[0064] like Figure 7 The figure shows the far-field distribution of the emitted light in different polarization states after being modulated by the metasurface. The left figure shows the emission of the left-hand circularly polarized (LCP) component. The bright spot indicates the emission direction and intensity of the light. The right figure shows the emission of the right-hand circularly polarized (RCP) component. The bright spot indicates the emission direction and intensity of the light. The metasurface demonstrates its ability to regulate light in different polarization states. It can be used to achieve polarization selectivity and enhance the emission of a specific polarization state.

[0065] Embodiment 3

[0066] This embodiment is an embodiment of a solid-state quantum light source, which is prepared using the solid-state quantum light source preparation method described in Embodiment 1.

[0067] In a solid-state quantum light source of this embodiment, the front microcolumns, quantum dots and back metasurface are aligned in space. The microcolumns can enhance the luminescence of quantum dots to achieve high brightness, high purity and high coherence. At the same time, the metasurface regulates the luminescence of quantum dots in dimensions including but not limited to phase and polarization, so as to realize a new solid-state quantum light source with high brightness, high purity, high coherence and strong micro-nano light field regulation capabilities.

[0068] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a solid-state quantum light source, characterized in that: The following steps are involved: S1. Preparation of front metal mark: Expose and develop the front side of the sample, evaporate metal after development and peel off; S2. Preparation of back metal mark: exposing and developing the back of the sample after step S1, and then evaporating the metal and peeling it off after development; S3. Positive quantum dot positioning: performing quantum dot positioning on the sample processed in step S2 to determine the position of the quantum dots; S4. Preparation of front microcolumns: preparing microcolumns on the front of the sample treated in step S3; S5. Flattening the front microcolumn: Flattening the sample after processing in step S4; S6. Preparation of back side super surface: Prepare a super surface on the back side of the sample processed in step S5.

2. The method for preparing a solid-state quantum light source according to claim 1, characterized in that: The sample includes, from bottom to top, a gallium arsenide substrate layer, a lower DBR layer, a quantum dot layer, and an upper DBR layer.

3. The method for preparing a solid-state quantum light source according to claim 1, characterized in that: The position where exposure is performed in step S1 and the position where exposure is performed in step S2 are aligned in terms of the front and back sides in the sample space position.

4. The method for preparing a solid-state quantum light source according to claim 1, characterized in that: In step S1 and step S2, the exposure uses PMMA electron beam photoresist with a thickness of 650nm to 750nm. The exposure parameters include beam current 8nA to 12nA, dose 600μC / cm 2 ~700μC / cm 2 The development uses MIBK developer, and the development time is 1min to 2min; the metal used for the evaporation includes gold, and the thickness is 100nm to 600nm; the stripping solution used for the stripping includes trichloroethylene solution or acetone.

5. The method for preparing a solid-state quantum light source according to claim 1, characterized in that: In step S3, quantum dot positioning includes exciting the quantum dots in the quantum dot layer to emit light by a high-power laser to determine and record the position of the quantum dots, where the position of the quantum dots is the position of the front metal mark in step S1.

6. The method for preparing a solid-state quantum light source according to claim 1, characterized in that: Step S4 includes exposure, etching and stripping; The exposure uses HSQ electron beam photoresist, and the exposure parameters include: beam current 4nA-6nA, dose 750μC / cm 2 ~850μC / cm 2 The etching includes etching using an inductively coupled plasma etcher, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 6:10:2, the chamber pressure is 5.5mTorr~6.5mTorr, the radio frequency voltage is 450W~550W, and the degumming includes degumming using a hydrofluoric acid solution.

7. The method for preparing a solid-state quantum light source according to claim 6, characterized in that: In step S4, the position exposed in step S4 is aligned with the position of the quantum dots in step S3.

8. The method for preparing a solid-state quantum light source according to claim 1, characterized in that: In step S5 , planarization includes spin coating the photoresist onto the sample and then curing it using an ultraviolet curing lamp.

9. The method for preparing a solid-state quantum light source according to claim 1, characterized in that: In step S6, preparing the metasurface includes exposure, etching and stripping; The exposure position is spatially aligned with the quantum dot position in step S3. The exposure uses HSQ electron beam photoresist. The exposure parameters include: beam current 0.7nA-0.9nA, dose 900μC / cm 2 ~1100μC / cm 2 The etching includes etching using an inductively coupled plasma etcher, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 2:10:1, the chamber pressure is 4.5mTorr~5.5mTorr, and the radio frequency voltage is 90W~110W; the degumming includes degumming using hydrofluoric acid.

10. A solid-state quantum light source, characterized in that: The solid-state quantum light source is prepared by the method for preparing the solid-state quantum light source according to any one of claims 1 to 9.

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