A method of manufacturing a solid state quantum light source

Abstract

The application relates to a solid-state quantum light source preparation method, which comprises the following steps: S1. Front metal mark preparation: exposing and developing the front of a sample, and then evaporating metal and stripping after development; S2. Back metal mark preparation: exposing and developing the back of the sample after step S1 treatment, and then evaporating metal and stripping after development; S3. Front quantum dot positioning: positioning quantum dots on the sample after step S2 treatment to determine the positions of the quantum dots; S4. Front microcolumn preparation: preparing microcolumns on the front of the sample after step S3 treatment; S5. Front microcolumn planarization: planarizing the sample after step S4 treatment; and S6. Back super surface preparation: preparing a super surface on the back of the sample after step S5 treatment. The application realizes high brightness, high purity and high coherence, and meanwhile, the super surface controls quantum dot light emission in dimensions including but not limited to phase and polarization, so that a novel solid-state quantum light source with high brightness, high purity, high coherence and strong micro-nano light field control capability is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-nano device preparation, and more particularly to a solid-state quantum light source preparation method. BACKGROUND

[0002] Single photon source is not only important in quantum information processing, quantum secure communication, quantum radar and quantum optical computing, but also has important application value in micro-absorption measurement, ultra-high sensitive magnetic field measurement, biological fluorescence labeling and imaging, etc. Among many single photon emission generation schemes, single photon source based on quantum dots has great advantages in all aspects compared with other single photon sources, such as narrow spectral line width, high oscillator strength, no light fading or flickering, small time jitter, high repetition frequency, emission wavelength covering from ultraviolet to infrared, suitable for electric pumping, etc. Generally, quantum dot emission single photons are isotropic, and the spontaneous emission efficiency in free space is low, resulting in low repetition frequency. Especially for group III nitride semiconductor materials, there is a strong spontaneous polarization and piezoelectric polarization field, which leads to electron-hole wave function separation (i.e. quantum confinement Stark effect), so that the spontaneous emission process is inhibited and the repetition frequency is limited. In most quantum technology applications, single photon source must have a high repetition frequency of GHz or more.

[0003] In order to improve the repetition frequency and emission efficiency of single photon source and obtain high-quality single photon source, quantum dots can be placed in a microcavity to utilize Purcell effect, that is, the spontaneous emission of quantum emitter in a microcavity can be greatly enhanced compared with that in free space, so that the quantum efficiency of single photon emission can be improved by using a microcavity. For electrically pumped devices, the presence of a microcavity can greatly reduce the operating voltage of electric injection, thereby improving the stability of the device. Usually, DBR microcavity or photonic crystal microcavity is used to obtain high-quality single photon source. However, although DBR microcavity can confine light in the vertical direction to produce high Purcell factor, it can only rely on the reflection of the microcylinder sidewall interface to confine light in the plane direction, which will cause obvious light leakage loss and form a photon emission channel of non-resonant wavelength, resulting in deterioration of single photon source performance; photonic crystal microcavity can confine photons in two or even three dimensions, which can further improve the light emission performance of quantum dots.

[0004] In the prior art, some use external superstructure surface as a discrete device to regulate on-chip quantum light source, which has very low integration level, and some are integrated devices, but lack of cavity enhancement effect and micro-nano light field regulation capability. SUMMARY

[0005] The present application aims to overcome the low integration and poor micro-nano light field regulation capability of the prior art, and provides a solid-state quantum light source preparation method, which has high integration and strong micro-nano light field regulation capability.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is:

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

[0008] S1. Front metal mark preparation: exposing and developing the front of the sample, and then evaporating metal and peeling off after development;

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

[0010] S3. Front quantum dot positioning: positioning quantum dots on the sample after step S2 processing to determine the position of the quantum dots;

[0011] S4. Front micro-column preparation: preparing a micro-column on the front of the sample after step S3 processing;

[0012] S5. Front micro-column planarization: planarizing the sample after step S4 processing;

[0013] S6. Back super surface preparation: preparing a super surface on the back of the sample after step S5 processing.

[0014] The solid-state quantum light source preparation method of the present application uses the metal mark preparation in steps S1 and S2 for quantum dot positioning in S3, and the positioning of micro-column preparation in step S4 and super surface preparation in step S6 to realize the alignment of the front micro-column, quantum dots and back super surface in spatial position. The micro-column can enhance the quantum dot light emission to achieve high brightness, high purity and high coherence, while the super surface regulates the quantum dot light emission in dimensions including but not limited to phase, polarization, etc. to achieve a new type of 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 exposed in step S1 and the position exposed in step S2 are aligned on the front and back of the sample in spatial position.

[0017] As preferred, in step S1 and step S2, the exposure uses PMMA (Polymethyl methacrylate) electron beam resist, thickness is 650nm-750nm, the exposure parameters include beam current 8nA-12nA, dose 600μC / cm 2 ~700μC / cm 2 ; the development uses MIBK (methyl isobutyl ketone) developer, development time is 1min-2min; the evaporation uses metal including gold, thickness is 100nm-600nm; the stripping uses stripping solution including trichloroethylene solution or acetone.

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

[0019] As preferred, step S4 includes exposure, etching and de-gluing; the exposure uses HSQ (Hydrogen Silsesquioxane Polymers) electron beam resist, the exposure parameters include: beam current 4nA-6nA, dose 750μC / cm 2 ~850μC / cm 2 ; the etching includes using an inductively coupled plasma etching machine to etch, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 6:10:2, the cavity gas pressure is 5.5mTorr-6.5mTorr, the radio frequency voltage is 450W-550W, and the de-gluing includes using a hydrofluoric acid solution to de-glue.

[0020] As preferred, in step S4, the position exposed in step S4 is aligned with the quantum dot position in step S3. The exposure position is opposite to the quantum dot position, and then the alignment of the micro-pillars and the quantum dots is realized.

[0021] As preferred, in step S5, the planarization includes spin coating a photoresist (SU8 reagent) to the sample and then curing using a UV curing lamp.

[0022] As preferred, in step S6, the preparation of the metasurface includes exposure, etching and de-gluing; the exposure position is spatially aligned with the quantum dot position in step S3, the exposure uses HSQ electron beam resist, 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 etching machine, the etching gas is silicon tetrachloride, argon and nitrogen, the proportion is 2:10:1, the cavity gas pressure is 4.5mTorr-5.5mTorr, and the radio frequency voltage is 90W-110W; and the glue removing includes removing glue using hydrofluoric acid.

[0023] The application further provides a solid-state quantum light source prepared by the solid-state quantum light source preparation method.

[0024] The solid-state quantum light source of the application is characterized in that the front micro-pillar, the quantum dot and the back super surface are aligned in spatial positions, the micro-pillar can enhance the quantum dot light emission, realize high brightness, high purity and high coherence, and the super surface can control the quantum dot light emission 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 control ability.

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

[0026] The solid-state quantum light source preparation method of the application realizes the alignment of the front micro-pillar, the quantum dot and the back super surface in spatial positions, the micro-pillar can enhance the quantum dot light emission, realize high brightness, high purity and high coherence, and the super surface can control the quantum dot light emission 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 control ability. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 FIG. 1 is a flowchart of the solid-state quantum light source preparation method of the application;

[0028] Figure 2 FIG. 2 is a preparation flowchart of the solid-state quantum light source preparation method of the application;

[0029] Figure 3 FIG. 3 is a micro-pillar structure diagram of the solid-state quantum light source preparation method of the application;

[0030] Figure 4 FIG. 4 is a super surface structure diagram of the solid-state quantum light source preparation method of the application.

[0031] Figure 5 FIG. 5 is a micro-cavity enhancement effect diagram of the quantum light source prepared by the solid-state quantum light source preparation method of the application.

[0032] Figure 6 FIG. 6 is a light modulation diagram of the quantum light source super surface prepared by the solid-state quantum light source preparation method of the application.

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

[0034] The application will be further described below in conjunction with specific embodiments. The accompanying drawings are only used for exemplary illustration, and the representations are only schematic diagrams, not physical drawings, and should not be understood as limiting the patent. In order to better illustrate the embodiments of the application, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual size of the product. It is understandable for those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0035] The same or similar reference numerals in the drawings of the embodiments of the application correspond to the same or similar components; in the description of the application, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore the terms describing the positional relationships in the drawings should not be understood as limiting the patent. For those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0036] Embodiment one

[0037] The present embodiment is a first embodiment of a solid quantum light source preparation method, as shown in Figure 1 and Figure 2 , comprising the following steps:

[0038] S1. Front metal mark preparation: exposing and developing the front of the sample, and then evaporating metal and peeling off after development;

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

[0040] S3. Front quantum dot positioning: positioning quantum dots on the sample after step S2 treatment to determine the position of the quantum dots;

[0041] S4. Front microcolumn preparation: preparing microcolumns on the front of the sample after step S3 treatment;

[0042] S5. Front microcolumn planarization: planarizing the sample after step S4 treatment;

[0043] S6. Back metasurface preparation: preparing a metasurface on the back of the sample after step S5 treatment.

[0044] In the embodiment, the sample sequentially 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.

[0045] In the embodiment, the position exposed in step S1 and the position exposed in step S2 are aligned in the sample space position, front and back.

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

[0047] In the embodiment, in step S3, the 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 quantum dot position, which is the position of the front metal mark in step S1.

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

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

[0050] In the embodiment, in step S5, the planarization includes spin-coating SU8 reagent to the sample and then curing using a UV curing lamp.

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

[0052] The solid-state quantum light source preparation method of the application uses the metal mark in steps S1 and S2 to prepare the quantum dot positioning for S3, and the positioning of the micro column preparation in step S4 and the super surface preparation in step S6 to realize the alignment of the front micro column, the quantum dot and the back super surface in the spatial position. The micro column can enhance the quantum dot light emission to realize high brightness, high purity and high coherence, and the super surface can regulate the quantum dot light emission in the dimensions including but not limited to phase and polarization to realize a new solid-state quantum light source with high brightness, high purity, high coherence and strong micro-nano light field regulation ability.

[0053] Embodiment two

[0054] The embodiment is a second embodiment of a solid-state quantum light source preparation method, which uses the solid-state quantum dot light source prepared in embodiment one for testing.

[0055] As shown in Figure 3 and Figure 4 , the micro column and the super structure surface prepared by the method of the application are shown, which realizes the alignment of the front micro column, the quantum dot and the back super surface in the spatial position.

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

[0057] The red curve represents the decay of the quantum dot in the microcavity, marked as "QD at resonance".

[0058] The blue curve represents the decay of the quantum dot in the bulk material, marked as "QD in bulk".

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

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

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

[0062] The quantum dots in the microcavity have shorter fluorescence lifetimes due to the cavity enhancement effect, indicating faster photon emission and enhanced quantum dot luminescence.

[0063] As shown in Figure 6 , the far-field distribution of the emitted light by the micro-pillar structure is shown, and this emission is modulated by the metasurface. The bright spots in the figure represent the direction and intensity of light emission. The bright spots in the figure represent the direction of light emission, and two angles are marked: θ = 10°, θ = 10° and θ = 15°, θ = 15°. These angles show the deviation of 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 light. It can be used to precisely control the emission characteristics of light and improve the performance of optical devices.

[0064] As shown in Figure 7 , the far-field distribution of the emitted light by the metasurface is shown. The left figure shows the emission of the left circularly polarized (LCP) component. The bright spots represent the direction and intensity of light emission. The right figure shows the emission of the right circularly polarized (RCP) component. The bright spots represent the direction and intensity of light emission. The ability of the metasurface to control light of different polarization states is demonstrated. It can be used to achieve polarization selectivity and enhance the emission of specific polarization states.

[0065] Embodiment Three

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

[0067] The solid-state quantum light source of this embodiment has a front micro-pillar, quantum dots, and a back metasurface aligned in space. The micro-pillar can enhance the luminescence of the quantum dots, achieving high brightness, high purity, and high coherence. Meanwhile, the metasurface modulates the luminescence of the quantum dots in dimensions including but not limited to phase and polarization, to achieve a new type of solid-state quantum light source with high brightness, high purity, high coherence, and strong micro-nano light field modulation capability.

[0068] In the specific content of the above specific embodiments, each technical feature can be combined in any manner without contradiction. To make the description concise, not all possible combinations of the above technical features are described, but as long as the combination of these technical features does not exist contradiction, it should be considered as the scope of the present disclosure.

[0069] Obviously, the above embodiments of the present application are merely exemplary but not intended to limit the embodiments of the present application. Based on the above description, any other variations or changes can be made by those skilled in the art without departing from the spirit and principles of the present application. It is not necessary to list all the embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall fall within the scope of the claims of the present application.

Claims

1. A method for preparing a solid-state quantum light source, characterized in that, The method comprises the following steps: S1. Front metal mark preparation: exposing and developing the front of the sample, evaporating metal after development and peeling off; S2. Back metal mark preparation: exposing and developing the back of the sample after step S1, evaporating metal after development and peeling off; S3. Front quantum dot positioning: positioning quantum dots on the sample after step S2 to determine the position of the quantum dots; S4. Front microcolumn preparation: preparing microcolumns on the front of the sample after step S3; S5. Front microcolumn planarization: planarizing the sample after step S4; S6. Back metasurface preparation: preparing a metasurface on the back of the sample after step S5; The metal mark preparation in step S1 and step S2 is used for the positioning of quantum dots in step S3, and the positioning of microcolumn preparation in step S4 and metasurface preparation in step S6, so as to realize the alignment of the front microcolumn, quantum dots and back metasurface in spatial position.

2. The method of claim 1, wherein the method further comprises: The sample comprises, 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 of claim 1, wherein the method further comprises: The position exposed in step S1 and the position exposed in step S2 are aligned in spatial position on the front and back of the sample.

4. The method of claim 1, wherein the method further comprises: In step S1 and step S2, the exposure uses PMMA electron beam resist, thickness is 650nm~750nm, exposure parameters include beam current 8nA~12nA, dose 600μC / cm 2 ~700μC / cm 2 ; the development uses MIBK developer, development time is 1min~2min; the evaporation adopts metal including gold, thickness is 100nm~600nm; the stripping uses stripping solution including trichloroethylene solution or acetone.

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

6. The method of claim 1, wherein the solid-state quantum light source is a quantum dot. Step S4 comprises exposure, etching and glue removal; The exposure uses HSQ electron beam resist, and the exposure parameters include: beam current 4nA-6nA, dose 750μC / cm 2 850μC / cm 2 The etching includes etching by using an inductively coupled plasma etching machine, the etching gas is silicon tetrachloride, argon and nitrogen, the proportion is 6:10:2, the cavity gas pressure is 5.5mTorr-6.5mTorr, the radio frequency voltage is 450W-550W, and the stripping includes stripping by using a hydrofluoric acid solution.

7. The method of claim 6, wherein the method further comprises: In step S4, the position exposed in step S4 is aligned with the position of the quantum dots in step S3.

8. The method of claim 1, wherein the solid state quantum light source is a quantum dot. In step S5, planarization comprises spin coating photoresist on the sample and curing with a UV curing lamp. ​ 9. The method of claim 1, wherein the solid-state quantum light source is a quantum dot. In step S6, the preparation of the metasurface comprises exposure, etching and glue removal; The position of the exposure is spatially aligned with the position of the quantum dot in step S3, the exposure uses HSQ electron beam resist, and 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 etching machine, the etching gas is silicon tetrachloride, argon and nitrogen, the ratio is 2:10:1, the cavity gas pressure is 4.5mTorr~5.5 mTorr, and the radio frequency voltage is 90W~110W; and the stripping includes stripping using hydrofluoric acid.

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

Images