Electrically regulated thin-film quantum dot light source and methods of making and using same

Abstract

The application provides an electrically regulated thin film quantum dot light source and a preparation method and use method thereof, and belongs to the field of semiconductor materials. The electrically regulated thin film quantum dot light source comprises, from bottom to top, a first substrate, a first composite protective layer, a P-type semiconductor doped layer, a first intrinsic layer, a quantum dot layer, a second intrinsic layer, an N-type semiconductor doped layer, a second composite protective layer, a first metal layer and a second metal layer, the first metal layer is in contact with the N-type semiconductor doped layer, and the second metal layer is in contact with the P-type semiconductor doped layer; the quantum dot layer comprises a III-V semiconductor quantum dot; the thickness of the first intrinsic layer is greater than the thickness of the second intrinsic layer, so that, in response to an external electric field applied on the first metal layer and the second metal layer, a bias electric field acting on the III-V semiconductor quantum dot is formed, the exciton state of holes and electrons generated after the III-V semiconductor quantum dot is excited by light is regulated, and the wavelength of the fluorescence generated by the recombination of the holes and the electrons is regulated.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials, and in particular to an electrically regulated thin-film quantum dot light source and its preparation and usage methods. Background Technology

[0002] Quantum light sources are an important component of quantum information and quantum computing. Semiconductor quantum dots, as a quantum light source with high practical value, are widely used in optical quantum communication and linear optical quantum computing. Furthermore, different photon states are required for different quantum information domains.

[0003] In related technologies, group III-V semiconductor quantum dots are mostly grown on homogeneous substrates. However, the fluorescence energy emitted by group III-V semiconductor quantum dots is higher than the band gap of the substrate material, causing the fluorescence emitted by the quantum dots to be absorbed by the substrate. This makes it difficult to effectively emit and collect the fluorescence, thus requiring the fabrication of group III-V semiconductor quantum dots into thin films. However, when transferring group III-V semiconductor quantum dots to other substrates, it is difficult to achieve effective control over the wavelength and exciton states of the quantum dots in the thin film morphology.

[0004] Therefore, it is necessary to find a thin-film quantum dot light source that can have high fluorescence emission efficiency while also enabling effective control of the exciton state and wavelength of the quantum dots. Summary of the Invention

[0005] In view of this, in order to at least partially solve the aforementioned technical problems, the present invention provides an electrically tunable thin-film quantum dot light source and its preparation and usage methods.

[0006] According to one aspect of the present invention, an electrically tunable thin-film quantum dot light source is provided, comprising: a first substrate, a first composite protective layer, a P-type semiconductor doped layer, a first intrinsic layer, a quantum dot layer, a second intrinsic layer, an N-type semiconductor doped layer, and a second composite protective layer stacked sequentially from bottom to top; a first metal layer and a second metal layer, wherein the first metal layer is disposed in a first groove penetrating the second composite protective layer and a portion of the N-type semiconductor doped layer, and the first metal layer is in contact with the N-type semiconductor doped layer; the second metal layer is disposed in a second groove penetrating the second composite protective layer, the N-type semiconductor doped layer, the second intrinsic layer, the quantum dot layer, the first intrinsic layer, and a portion of the P-type semiconductor doped layer, and the second metal layer is in contact with the P-type semiconductor doped layer; the quantum dot layer includes at least one group III-V semiconductor quantum dot; wherein the thickness of the first intrinsic layer is greater than the thickness of the second intrinsic layer, so as to be able to form a bias electric field acting on the group III-V semiconductor quantum dot in response to an external electric field applied to the first metal layer and the second metal layer, thereby controlling the exciton states of holes and electrons generated after the group III-V semiconductor quantum dot is photoexcited, and controlling the wavelength of fluorescence generated by the recombination of holes and electrons.

[0007] According to another aspect of the present invention, a method for fabricating an electrically tunable thin-film quantum dot light source as described above is provided, comprising: sequentially forming a second composite protective layer, an N-type semiconductor doped layer, a second intrinsic layer, a quantum dot layer, a first intrinsic layer, a P-type semiconductor doped layer, and a first composite protective layer on a second substrate to form a quantum dot semiconductor structure on the second substrate; transferring the quantum dot semiconductor structure to a first substrate by bonding or molecular bonding; etching from the second composite protective layer to the N-type semiconductor doped layer to form a first groove, and depositing a first metal layer in the first groove; etching from the second composite protective layer to the P-type semiconductor doped layer to form a second groove, and depositing a second metal layer in the second groove to obtain a sample; annealing the sample, and drawing wires from the first metal layer and the second metal layer respectively to obtain an electrically tunable thin-film quantum dot light source; wherein the annealing temperature is 160~200℃.

[0008] According to another aspect of the technical solution of the present invention, a method for using the electrically regulated thin-film quantum dot light source as described above is provided, comprising: using a regulated power supply, determining the exciton states of at least one group III-V semiconductor quantum dot of the electrically regulated thin-film quantum dot light source under different voltages under a first optical excitation, and determining the target voltage corresponding to the target exciton state; using a DC voltage consistent with the target voltage, resonantly exciting at least one group III-V semiconductor quantum dot of the electrically regulated thin-film quantum dot light source under a second optical excitation to obtain a single photon or an entangled photon pair; wherein the wavelength of the second optical excitation is greater than the wavelength of the first optical excitation.

[0009] Based on the above technical solution, the electrically controlled thin-film quantum dot light source, its preparation method, and its usage method provided by the present invention have at least the following beneficial effects:

[0010] This invention places a quantum dot layer within the intrinsic region (I layer) of a PN junction. Under photoexcitation, the quantum dot layer directly generates holes and electrons. The difference in thickness between the intrinsic layers (first and second intrinsic layers) on either side of the quantum dot layer facilitates the formation of bias electric fields of varying intensities acting on at least one group III-V semiconductor quantum dot. This causes a wavelength shift in the emitted fluorescence, known as the Stark effect, enabling tuning of the emitted fluorescence over a wider range and improving the efficiency of electrically controlled thin-film quantum dot light sources. Simultaneously, the difference in intrinsic layer thickness presupposes structural asymmetry, resulting in different rates of electron and / or hole entry and exit from the group III-V semiconductor quantum dot under an applied electric field, thus deterministically achieving exciton state modulation. Furthermore, by forming the quantum dot layer within a thin film, rather than directly growing it on a thicker homogeneous substrate, the self-absorption of quantum dot emission by the homogeneous substrate is effectively eliminated, further improving fluorescence extraction and collection efficiency. Attached Figure Description

[0011] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings.

[0012] Figure 1a A schematic diagram of the structure of an electrically tunable thin-film quantum dot light source according to an embodiment of the present invention is shown;

[0013] Figure 1b A schematic diagram of the structure of an electrically tunable thin-film quantum dot light source according to another embodiment of the present invention is shown;

[0014] Figure 2 A flowchart illustrating the fabrication method of an electrically controlled thin-film quantum dot light source according to an embodiment of the present invention is shown;

[0015] Figure 3 A process flow diagram of an electrically tunable thin-film quantum dot light source according to a specific embodiment of the present invention is shown;

[0016] Figure 4a The current-voltage curves of the N terminal formed in Comparative Example 1 at a temperature of 300K are shown.

[0017] Figure 4b The current-voltage curve of the N terminal formed in Example 1 at a temperature of 300K is shown.

[0018] Figure 5a The current-voltage curve of the N-terminus of the sample formed in Example 2 at a temperature of 300K is shown.

[0019] Figure 5b The current-voltage curve of the P-terminus of the sample formed in Example 2 at a temperature of 300K is shown.

[0020] Figure 5c The current-voltage curve of the PN junction of the sample formed in Example 2 at a temperature of 300K is shown.

[0021] Figure 5d The current-voltage curve of the PN junction of the sample formed in Example 2 at a low temperature of 6K is shown.

[0022] Figure 6a The spectrum of quantum dot 1-1 characterized by continuous light at 532 nm is shown in Application Example 1.

[0023] Figure 6b The spectrum of quantum dots 1-2 characterized by continuous light at 532 nm is shown in Application Example 1.

[0024] Figure 6c The spectrum of quantum dots 1-3 characterized by continuous light at 532 nm is shown in Application Example 1.

[0025] Figure 7a The spectrum of quantum dot 2-1 characterized by continuous light at 532 nm is shown in Comparative Application Example 1.

[0026] Figure 7b The spectrum of quantum dot 2-2 characterized by band-mounted light using continuous light at 532 nm is shown in Comparative Application Example 1.

[0027] In the above figures, the reference numerals are as follows:

[0028] 1. First substrate; 2. First composite protective layer; 3. P-type semiconductor doped layer; 4. First intrinsic layer; 5. Quantum dot layer; 51. Group III-V semiconductor quantum dot; 6. Second intrinsic layer; 7. N-type semiconductor doped layer; 8. Second composite protective layer; 9. First metal layer; 10. Second metal layer. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0031] Group III-V semiconductor quantum dots, such as gallium arsenide quantum dots, have great potential as quantum light sources due to their three-dimensional confined structure that generates discrete energy levels. To obtain high-quality and stable quantum dot quantum light sources, related technologies often use homogeneous gallium arsenide substrates for epitaxy. The fluorescence wavelength of gallium arsenide quantum dots is around 790 nm, which is higher than the band gap of gallium arsenide (GaAs) bulk material, resulting in strong absorption by the homogeneous gallium arsenide substrate.

[0032] To address the aforementioned technical challenges, attempts have been made to integrate quantum dots onto other substrates using thin films to improve fluorescence collection efficiency. However, different applications within the quantum information field require different exciton states. Thin-film quantum dot light sources typically cannot simultaneously achieve both exciton state and wavelength modulation.

[0033] Furthermore, by forming a thin-film quantum dot light source on a first substrate and setting a thickness difference between the intrinsic layers on both sides of the quantum dot layer, a biased electric field is formed by the difference between the applied electric field and the thickness of the intrinsic layers and applied to the III-V semiconductor quantum dots. This allows for both good wavelength modulation and exciton state modulation effects while improving fluorescence emission efficiency.

[0034] Specifically, according to one embodiment of the present invention, an electrically tunable thin-film quantum dot light source is provided. Figure 1a A schematic diagram of the structure of an electrically tunable thin-film quantum dot light source according to an embodiment of the present invention is shown; Figure 1b A schematic diagram of the structure of an electrically tunable thin-film quantum dot light source according to another embodiment of the present invention is shown. Figures 1a-1b As shown, the electrically regulated thin-film quantum dot light source includes: a first substrate 1, a first composite protective layer 2, a P-type semiconductor doped layer 3, a first intrinsic layer 4, a quantum dot layer 5, a second intrinsic layer 6, an N-type semiconductor doped layer 7, a second composite protective layer 8, a first metal layer 9, and a second metal layer 10, which are stacked sequentially from bottom to top.

[0035] The first substrate 1 serves as a support for the electrically tunable thin-film quantum dot light source, providing a flat and clean mechanical platform for the overlying thin film. The first substrate 1 can also interact with the overlying thin film. The first composite protective layer 2 is located between the first substrate 1 and the P-type semiconductor doped layer 3, providing protection for the P-type semiconductor doped layer 3 and reducing its oxidation. The P-type semiconductor doped layer 3 and the N-type semiconductor doped layer 7 are the carrier injection layers for the electrically tunable thin-film quantum dot light source. The first intrinsic layer 4 and the second intrinsic layer 6 are used to regulate the rate at which electrons or holes tunnel into the quantum dot layer 5. More specifically, the second intrinsic layer 6 controls the rate at which electrons tunnel into or out of the quantum dot layer 5, thereby regulating the exciton state of the quantum dots. The quantum dot layer 5 is the source of light emission for the electrically tunable thin-film quantum dot light source, including at least one group III-V semiconductor quantum dot 51 (hereinafter referred to as quantum dot). Quantum dots are semiconductor structures with dimensions at the nanometer scale. When the quantum dots are photoexcited, they generate electrons and holes, which recombine in the quantum dot layer 5 and emit fluorescence. The second composite protective layer 8 is located above the N-type semiconductor doped layer 7, providing protection for the N-type semiconductor doped layer 7 and reducing the oxidation of the N-type semiconductor doped layer 7.

[0036] A first metal layer 9 is disposed in a first groove penetrating the second composite protective layer 8 and a portion of the N-type semiconductor doped layer 7. The first metal layer 9 is in contact with the N-type semiconductor doped layer 7 and serves as an N-type electrode (which can be understood as a negative electrode). It directly contacts the N-type semiconductor doped layer 7 through the first groove and is connected to the first electrode of an external power supply. A second metal layer 10 is disposed in a second groove penetrating the second composite protective layer 8, the N-type semiconductor doped layer 7, the second intrinsic layer 6, the quantum dot layer 5, the first intrinsic layer 4, and a portion of the P-type semiconductor doped layer 3. The second metal layer 10 is in contact with the P-type semiconductor doped layer 3 and serves as a P-type electrode (which can be understood as a positive electrode). It directly contacts the P-type semiconductor doped layer 3 through the second groove and is connected to the second electrode of an external power supply, thereby forming an applied electric field between the N-type semiconductor doped layer 7 and the P-type semiconductor doped layer 3.

[0037] The thickness of the first intrinsic layer 4 is greater than that of the second intrinsic layer 6, so that it can respond to the external electric field applied to the first metal layer 9 and the second metal layer 10 to form a bias electric field acting on the quantum dot, thereby regulating the exciton states of holes and electrons generated after the quantum dot is photoexcited, and regulating the wavelength of fluorescence generated by the recombination of holes and electrons.

[0038] According to an embodiment of the present invention, by forming a stacked thin film structure, the quantum dot layer 5 directly generates electrons and holes under photoexcitation, and the electrons and holes recombine to emit fluorescence. By adjusting the thickness of the second intrinsic layer 6 to be thinner, electric fields of different intensities are applied to the quantum dots, causing the wavelength of single photons emitted by at least one quantum dot to shift, i.e., the Stark effect, thereby achieving tuning over a wider range of fluorescence wavelengths. Based on the thickness difference of the intrinsic layers, the asymmetry in the electrically controlled thin film quantum dot light source structure is pre-defined, so that when a voltage is applied, the rates at which holes and electrons enter and escape from the quantum dots are different, thereby deterministically achieving the modulation of exciton states (e.g., charged exciton states or neutral exciton states).

[0039] Understandable. Figure 1a and Figure 1b For illustrative purposes only, the quantum dot layer 5 can contain one or more quantum dots. When there is only one quantum dot, the thickness difference of the intrinsic layers can be adjusted so that the quantum dot is in a charged exciton state when used in open microcavities, and in a neutral exciton state when used in waveguide microcavities. When used for polarization-entangled photon pairs, it is in a neutral exciton state. The control of the exciton state can be specifically adjusted according to the quantum subfield of the subsequent application; this invention does not impose any particular limitation on this.

[0040] Furthermore, it can be understood that quantum dots need to generate electron-hole pairs through photoexcitation and recombine at the quantum dot to emit fluorescence (which can be a single photon or an entangled photon pair). In the case where quantum dot layer 5 contains multiple quantum dots, the exciton state is first confirmed based on the subsequent application scenario, and then the thickness difference of the intrinsic layers on both sides of quantum dot layer 5 is confirmed. Since the volume and morphology of multiple quantum dots are different, based on the quantum confinement effect, the energy of the electron-hole pairs at multiple quantum dots is different. By finely adjusting the voltage of the applied electric field, the wavelength of fluorescence emitted by multiple quantum dots under the same exciton state can be made consistent.

[0041] In some implementations, the thicknesses of the first intrinsic layer 4 and the second intrinsic layer 6 jointly determine the Stark coefficient of the quantum dot. Assuming the thickness of the second intrinsic layer 6 is X nm and the thickness of the first intrinsic layer 4 is Y nm, the Stark coefficient of the quantum dot is proportional to 1 / (X+Y), and the energy difference between the quantum dot and the N-type semiconductor doped layer 7 is proportional to X / (X+Y). Therefore, with a fixed value of X, a larger Y results in a decrease in the wavelength modulation capability of the quantum dot, while a smaller Y results in an excessively large built-in electric field in the PN junction, leading to a decrease in the exciton state modulation capability of the quantum dot.

[0042] In some embodiments, the thickness ratio of the first intrinsic layer 4 to the second intrinsic layer 6 is (3~6):1. By adjusting the thickness ratio within the aforementioned range, noise on the surface of the quantum dot and the electrically controlled thin-film quantum dot light source can be effectively isolated, and at least some of the exciton states present in the quantum dots can appear or disappear with changes in voltage, thus enabling the electrically controlled thin-film quantum dot light source to have good exciton state modulation capabilities. Furthermore, for quantum dots of different volumes, the Stark effect can be achieved, enabling wavelength modulation. Especially in the case of multiple quantum dots, for example, by selecting quantum dots with similar emission wavelengths, and by fine-tuning the voltage, multiple quantum dots on the same first substrate 1 can emit a quantum light source with a consistent wavelength, improving the scalability of the quantum light source.

[0043] Optionally, the ratio of the thickness of the first intrinsic layer 4 to the thickness of the second intrinsic layer 6 may be, for example, 3:1, 4:1, 5:1, 16:3 or 6:1, or a range consisting of any two of the above ratios.

[0044] In some embodiments, the thickness of the first intrinsic layer 4 is 150-200 nm, preferably 160 nm. The thickness of the second intrinsic layer 6 can be 20-40 nm, preferably 30 nm. This configuration, based on the thickness of both layers, maintains the thin film structure of the electrically tunable thin-film quantum dot light source while also achieving superior exciton state modulation and wavelength modulation performance for fluorescence emission.

[0045] Optionally, the thickness of the first intrinsic layer 4 may be, for example, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm or 200 nm, or a range consisting of any two of the above values.

[0046] Optionally, the thickness of the second intrinsic layer 6 may be, for example, 20 nm, 30 nm, or 40 nm, or a range consisting of any two of the above values.

[0047] In some embodiments, the first substrate 1 includes any one of gallium arsenide, single-crystal silicon, and lithium niobate. It is understood that when the formed electrically controlled thin-film quantum dot light source is a thin film with a thickness on the order of hundreds of nanometers, the type of the first substrate 1 is not overly restricted. Preferably, the first substrate 1 can be an optoelectronic material or a material that is easy to integrate, such as lithium niobate or single-crystal silicon.

[0048] In some embodiments, the first substrate 1 and the first composite protective layer 2 are connected by adhesive bonding or molecular bonding. The two can be effectively connected through the interaction of adhesives, van der Waals forces, or molecular bonds. When the two are connected by adhesive bonding, for example, they can be bonded together with photoresist, preferably an epoxy resin-based photoresist. In this case, the adhesive can form an adhesive layer (not shown in the figure), and the thickness of the adhesive layer can be 500 nm.

[0049] In some embodiments, the material of the first metal layer 9 includes at least one of palladium, germanium, or gold; and the material of the second metal layer 10 includes at least one of titanium or gold. During the screening process for the material of the first metal layer 9, it was found that conventional combinations of titanium or gold are difficult to prepare good ohmic contacts, while increasing the doping concentration of the N-type semiconductor doped layer 7 leads to strong light absorption, affecting the collection efficiency of the fluorescence emitted by the quantum dot.

[0050] In some preferred embodiments, the material of the first metal layer 9 is a combination of palladium, germanium, and gold. By adjusting the material of the first metal layer 9 to the aforementioned metal combination, the present invention can maintain good ohmic contact while keeping the doping concentration of the N-type semiconductor doped layer 7 low, thereby significantly suppressing additional light absorption caused by free carriers and improving the stability of electrically controlled thin-film quantum dot light sources.

[0051] In some specific embodiments, the first metal layer 9 may be a palladium layer with a thickness of 10 nm, a germanium layer with a thickness of 35 nm, and a gold layer with a thickness of 100 nm stacked sequentially.

[0052] In some embodiments, the materials of the first intrinsic layer 4 and the second intrinsic layer 6 independently include one of the following: gallium arsenide, aluminum arsenide, and aluminum gallium arsenide. The above materials can be lattice-matched with the materials of the quantum dot layer 5 and form a high barrier to confine charge carriers and improve the quantum efficiency of the device.

[0053] It should be noted that, in order to achieve simultaneous modulation of exciton states and wavelength, the thickness of the second intrinsic layer 6 must first be controlled. Since the exciton state of the quantum dot is affected by the electron tunneling time of the N-type semiconductor doped layer 7, a lower thickness of the second intrinsic layer 6 results in a shorter electron tunneling time into the quantum dot, making the quantum dot more prone to a negative exciton state, which is detrimental to exciton state modulation. Simultaneously, a thinner second intrinsic layer 6 is less effective at preventing the segregation of N-type dopants (such as silicon) into the quantum dot during growth, and N-type dopants, as impurities, strongly degrade the luminescence of the quantum dot. Therefore, the second intrinsic layer 6 can be set as a 15nm thick Al layer grown at a low temperature (e.g., 550℃). 0.2 Ga 0.8 As and 15nm Al 0.4 Ga 0.6 Combinations of As, where Al 0.4 Ga 0.6 As is placed closer to quantum dot layer 5, this arrangement helps to balance the issues of exciton state modulation and N-type dopant segregation. Simultaneously, it avoids the complete use of Al. 0.4 Ga 0.6 The purpose of As is to increase the rate at which electrons tunnel into the quantum dot, thereby compensating for the reduction in tunneling rate caused by thickness.

[0054] It's understandable, "Al" 0.2 Ga 0.8 The number in "As" indicates the atomic ratio of aluminum and gallium in Group 3 elements. "Al" 0.4 Ga 0.6 The same applies to "As", so I will not repeat it here.

[0055] In some embodiments, the material of the quantum dot layer 5 includes at least one of the following: gallium arsenide, aluminum gallium arsenide, indium arsenide, indium gallium arsenide, and indium phosphide. This arrangement helps to achieve efficient and stable photon emission over a wide wavelength range.

[0056] In some specific embodiments, the quantum dots in quantum dot layer 5 can be gallium arsenide quantum dots, and the region outside the quantum dots in quantum dot layer 5 can be gallium aluminum arsenide, to form a structure in which gallium aluminum arsenide encapsulates gallium arsenide quantum dots. More specifically, the filling thickness of gallium arsenide quantum dots in quantum dot layer 5 can be, for example, 2 nm.

[0057] In some embodiments, the host material of the semiconductor doped layer can be selected from semiconductor materials such as gallium arsenide, aluminum arsenide, and aluminum gallium arsenide, and these semiconductor materials can be single-crystal types. By introducing donor impurities such as silicon into the aforementioned semiconductor materials, N-type materials are obtained; by introducing acceptor impurities such as beryllium and carbon into the aforementioned semiconductor materials, P-type materials are obtained.

[0058] In some embodiments, the material of the N-type semiconductor doped layer includes at least one of the following: N-type doped gallium arsenide, N-type doped aluminum arsenide, N-type doped aluminum gallium arsenide, and more specifically, silicon doped of the above materials.

[0059] In some preferred embodiments, the silicon doping concentration can be, for example, 2E18 to 4E18 atoms / cm³. 3 .

[0060] In some embodiments, the material of the P-type semiconductor doped layer includes at least one of the following: P-type doped gallium arsenide, P-type doped aluminum arsenide, P-type doped aluminum gallium arsenide, and more specifically, beryllium or carbon doped with the above materials.

[0061] In some preferred embodiments, the carbon doping concentration can be, for example, 2E18 to 1E19 atoms / cm³. 3 .

[0062] In some embodiments, the thicknesses of the P-type semiconductor doped layer 3 and the N-type semiconductor doped layer 7 are 30~50nm, for example, 30nm, 35nm, 40nm, 45nm or 50nm, or a range consisting of any two of the above values.

[0063] More specifically, the thickness of the P-type semiconductor doped layer 3 can be 35 nm, and the thickness of the N-type semiconductor doped layer 7 can be 30 nm.

[0064] In some embodiments, the thickness of the quantum dot layer 5 is 6-10 nm, wherein the filling thickness of the quantum dots can be 2 nm, and the thickness of the quantum dot layer 5 formed therefrom is preferably 8 nm.

[0065] In some embodiments, the thicknesses of the first composite protective layer 2 and the second composite protective layer 8 are 30-60 nm, respectively. This configuration further provides effective protection for the inner semiconductor doped layer, preventing its oxidation and failure.

[0066] Optionally, the thickness of the first composite protective layer 2 and the second composite protective layer 8 can each be independently 30nm, 40nm, 50nm or 60nm, or a range consisting of any two of the above values.

[0067] In some embodiments, the first composite protective layer 2 and the second composite protective layer 8 independently comprise, from near the quantum dot layer 5 to away from the quantum dot layer 5, a gallium arsenide aluminum layer, a gallium arsenide layer, and an aluminum oxide layer. It is understood that the film thickness of the electrically controlled thin-film quantum dot light source is on the order of hundreds of nanometers. The translational symmetry of the gallium arsenide layer material in the composite protective layers (first composite protective layer 2 and second composite protective layer 8) disappears on both the upper and lower surfaces. Therefore, intrinsic surface states are generated on both the upper and lower surfaces of the film, affecting the optical properties of the quantum dot. Simultaneously, the gallium arsenide aluminum layer is easily oxidized in air and cannot be directly exposed. Therefore, the first composite protective layer 2 and the second composite protective layer 8 respectively utilize the aforementioned three-layer structure, achieving secondary passivation and in-situ passivation effects, suppressing the influence of surface states and oxidation on the quantum dot device (i.e., the electrically controlled thin-film quantum dot light source), and improving the operating life of the quantum dot device.

[0068] In conventional bulk quantum dot light sources, a top protective layer can be optionally included or omitted. For example, directly exposing the N-type or P-type semiconductor doped layer to air can also protect the bulk quantum dot light source. Alternatively, if a top protective layer is present, its thickness can be less than 10 nm.

[0069] In this invention, the thickness of the gallium arsenide aluminum layer in both the first composite protective layer 2 and the second composite protective layer 8 must be greater than 20 nm. This is because the quantum dot device film generates numerous surface states and defects at the interface between the interface with the first substrate 1 and the air interface. Conventional passivation methods are insufficient to provide adequate protection for the quantum dot device, significantly impacting the quality of the internal semiconductor doped layer.

[0070] In some specific embodiments, the first composite protective layer 2, from near the quantum dot layer 5 to away from the quantum dot layer 5, includes a 40nm thick aluminum gallium arsenide layer (e.g., Al). 0.2 Ga 0.8 As), a 5nm thick gallium arsenide layer and a 5nm thick aluminum oxide layer.

[0071] According to another aspect of the present invention, a method for preparing the above-described electrically controlled thin-film quantum dot light source is provided. Figure 2 A flowchart illustrating the fabrication method of an electrically controlled thin-film quantum dot light source according to an embodiment of the present invention is shown, as follows: Figure 2 As shown, the preparation method includes operations S201 to S205.

[0072] In operation S201, a second composite protective layer 8, an N-type semiconductor doped layer 7, a second intrinsic layer 6, a quantum dot layer 5, a first intrinsic layer 4, a P-type semiconductor doped layer 3, and a first composite protective layer 2 are sequentially formed on a second substrate (not shown in the figure) to form a quantum dot semiconductor structure on the second substrate.

[0073] In operation S202, the quantum dot semiconductor structure is transferred onto the first substrate 1 by means of adhesion or molecular bonding.

[0074] In operation S203, the second composite protective layer 8 is etched down to the N-type semiconductor doped layer 7 to form a first groove, and a first metal layer 9 is deposited in the first groove.

[0075] In operation S204, the second composite protective layer 8 is etched down to the P-type semiconductor doped layer 3 to form a second groove, and a second metal layer 10 is deposited in the second groove to obtain a sample.

[0076] In operation S205, the sample is annealed, and wires are drawn from the first metal layer 9 and the second metal layer 10 respectively to obtain an electrically tunable thin-film quantum dot light source.

[0077] According to an embodiment of the present invention, the annealing temperature is 160~200℃. Based on the need to prepare the thin film structure of the electrically tunable thin-film quantum dot light source, it is necessary to adjust the thickness of the semiconductor doped layer to be relatively thin at the nanometer level. However, preparing the P-type semiconductor doped layer 3 and N-type semiconductor doped layer 7 requires the work function of the metal layer material to be matched with that of the semiconductor doped layer material, or heavy doping to be formed in the semiconductor doped layer. This necessitates using a composite metal material of germanium, nickel, and gold, or a composite metal material of zinc and gold as the metal layer for high-temperature annealing. However, because the thin film structure of the quantum dot device is relatively thin, excessive metal penetration during annealing can lead to short circuits in the device structure. Furthermore, the mechanical strength and properties of the thin film are affected; high-temperature annealing can cause significant stress or even damage to the thin film. Based on this, by screening the materials of the first metal layer 9 and the second metal layer 10 and adjusting the annealing treatment within the aforementioned temperature range, the present invention ensures the integrity of the thin film structure while eliminating the need for high doping concentration, suppressing the additional light absorption caused by free carriers, further improving the stability of the quantum dot device, and enabling the introduction of a quantum dot layer 5 into the intrinsic layer, and the formation of a low-temperature (e.g., below 10K) PN junction on the outside of the quantum dot layer, thereby achieving a dual control effect of wavelength adjustment and exciton state adjustment for the quantum dot.

[0078] Optionally, the annealing temperature may be, for example, 160°C, 180°C, or 200°C, or a range between any two of the above values, preferably 180°C.

[0079] In some specific embodiments, in operation S201, the aforementioned stacked structure can be formed, for example, by molecular beam epitaxy and atomic layer deposition. In operation S202, the bonding method can be, for example, using an epoxy resin-based photoresist (model SU8 2000.5). The molecular bonding method can be, for example, using plasma-assisted bonding, where the surface of the aforementioned stacked structure and the first substrate are subjected to plasma treatment, followed by pressure heating in a vacuum environment, and bonding is completed after a period of time. In operations S203 and S204, the etching method can be, for example, chemical solution wet etching to complete the patterning preparation. The deposition of metal layers (first metal layer 9 and second metal layer 10) can be performed, for example, by physical vapor deposition. In operation S205, the annealing treatment can be performed by placing the above sample on a hot plate for annealing.

[0080] The first composite protective layer 2 and the second composite protective layer 8 can each have an aluminum gallium arsenide layer, a gallium arsenide layer and an aluminum oxide layer in the direction from the quantum dot layer to the direction away from the quantum dot layer, respectively. The aluminum gallium arsenide layer and the gallium arsenide layer can be grown with other layers (such as semiconductor doped layers, intrinsic layers and quantum dot layers) by molecular beam epitaxy, and the aluminum oxide layer can be formed by atomic layer deposition.

[0081] In one specific embodiment, the semiconductor portion (e.g., aluminum gallium arsenide layer, gallium arsenide layer, etc.) of the second composite protective layer 8, the second intrinsic layer 6, the quantum dot layer 5, the first intrinsic layer 4, the p-type semiconductor doped layer 3, and the semiconductor portion (e.g., aluminum gallium arsenide layer, gallium arsenide layer, etc.) of the first composite protective layer 2 can be sequentially grown by molecular beam epitaxy. Then, the aluminum oxide layer of the first composite protective layer 2 is formed by atomic layer deposition. After transferring the quantum dot semiconductor structure onto the first substrate 1 and thinning and removing the second substrate, the aluminum oxide layer in the second composite protective layer 8 is formed by atomic layer deposition. It can be understood that the process of forming the aluminum oxide layer in the second composite protective layer 8 can be performed before or after annealing, and the present invention does not particularly limit this.

[0082] Figure 3 A process flow diagram of an electrically controlled thin-film quantum dot light source according to a specific embodiment of the present invention is shown below. Figure 3 Taking this as an example, the fabrication process of electrically controlled thin-film quantum dot light sources will be described in detail.

[0083] In operation S1, the quantum dot semiconductor structure prepared in operation S201 is transferred to a new gallium arsenide substrate with a thickness of 625 μm by adhesive bonding to obtain a quantum dot film.

[0084] In operation S2, the groove pattern structure on the P-end side is exposed, and a second metal layer 10 is etched and deposited using S1813 photoresist with a spin coating parameter of 3000 r / min and a thickness of approximately 800 nm. Then, a wet etching solution with a volume ratio of H2SO4:H2O2:H2O = 4:4:200 is used at an etching rate of approximately 1 to 2 nm / s. Ti is deposited sequentially to a thickness of 10 nm and Au to a thickness of 100 nm using electron beam evaporation to form the second metal layer 10, and then the remaining metal is removed by stripping.

[0085] In operation S3, the groove pattern on the N-end side is exposed, and the first metal layer 9 is etched and deposited using S1813 photoresist with a spin-coating parameter of 3000 r / min and a thickness of approximately 800 nm. Then, a wet etching solution with a volume ratio of H2SO4:H2O2:H2O = 4:4:200 is used at an etching rate of approximately 1 to 2 nm / s. Pd is deposited sequentially at a thickness of 10 nm, Ge at 35 nm, and Au at 100 nm using electron beam evaporation to form the first metal layer 9. The remaining metal is then removed by stripping to obtain the sample.

[0086] In operation S4, the sample is placed on a hot plate at 180°C and heated for 60 minutes in an atmospheric atmosphere, and then cooled to room temperature to obtain the annealed sample.

[0087] In operation S5, the upper surface of the annealed sample is selectively passivated using atomic layer deposition, depositing approximately 5 nm of Al2O3 to form the aluminum oxide layer in the second composite protective layer 8, protecting the annealed sample from oxidation. Then, a wet etching solution with a volume ratio of H2SO4:H2O2:H2O = 4:4:200 is used to etch for 10 seconds to remove the Al2O3 from the metal electrodes (which can be the first metal electrode and the second metal electrode) formed by the first metal layer 9 and the second metal layer 10, respectively.

[0088] In operation S6, the aforementioned sample is wire-encapsulated. One end of the aluminum wire can be attached to the first and second metal electrodes using silver paste, and the other end can be connected to an electrode of the same polarity that is led out to the power source, thereby completing the fabrication of an electrically regulated thin-film quantum dot light source.

[0089] According to another aspect of the present invention, a method for using the electrically regulated thin-film quantum dot light source as described above is provided, comprising: using a regulated power supply, determining the exciton states of at least one III-V semiconductor quantum dot of the electrically regulated thin-film quantum dot light source under different voltages under a first photoexcitation, and determining the target voltage corresponding to the target exciton state; using a DC voltage consistent with the target voltage, resonantly exciting at least one III-V semiconductor quantum dot of the electrically regulated thin-film quantum dot light source under a second photoexcitation to obtain a single photon or an entangled photon pair.

[0090] According to an embodiment of the present invention, the wavelength of the second photoexcitation is greater than the wavelength of the first photoexcitation. During use, due to slight differences in the size and stress state of the quantum dots within the same quantum dot layer 5, it is difficult to guarantee that each quantum dot is in an ideal quantum state if a preset voltage is directly applied. By first using a shorter wavelength for the first photoexcitation and voltage scanning, the quantum state of the quantum dots is adjusted to the target exciton state (e.g., a neutral exciton state for generating entangled photon pairs or a charged exciton state for generating single photons) requiring a target voltage. Then, a DC target voltage is used to suppress background (e.g., semiconductor doped layers and intrinsic layers) from producing broadband background fluorescence, resulting in high single-photon purity for single-photon sources and reduced spectral line drift.

[0091] Furthermore, the first optical excitation has a shorter wavelength and higher energy, which facilitates rapid characterization of the exciton state of the quantum dot. The second optical excitation, on the other hand, is a resonant excitation, which is performed by pulsed light to improve the emission efficiency of single photons or entangled photon pairs.

[0092] In some specific implementations, the wavelength of the first optical excitation can be, for example, a continuous excitation light of 532 nm, and the wavelength of the second optical excitation can be adjusted according to the actual quantum dot application scenario. The present invention does not impose any particular limitation on the wavelength of the second optical excitation.

[0093] In some implementations, the voltage of the regulated power supply is 0.2~1.7V. This setting can be adjusted according to the actual needs of the target exciton state, and the present invention does not limit this.

[0094] In some specific implementations, the turn-on voltage of the PN junction of the formed electrically regulated thin-film quantum dot light source can be 1.3V at room temperature and 1.7V at low temperatures (below 10K, for example, 6K).

[0095] The present invention will be further illustrated below through embodiments and related test experiments and results. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict.

[0096] It should be noted that the specific embodiments described below are merely illustrative examples, and the scope of protection of this invention is not limited thereto. The chemicals and raw materials used in the following embodiments are all commercially available or prepared using recognized processing methods.

[0097] Comparative Example 1: Preparation of the N-terminal structure

[0098] Layers B and A, as shown in Table 1, are formed from bottom to top using molecular beam epitaxy as described above. They are then transferred to a gallium arsenide substrate (layer D) by adhesive bonding (layer C). The doping concentration and thickness of each layer are shown in Table 1.

[0099] Table 1

[0100]

[0101] Example 1: Fabrication of N-terminal structure

[0102] Layers B and A, as shown in Table 2, are formed from bottom to top using molecular beam epitaxy as described above. They are then transferred to a gallium arsenide substrate (layer D) by adhesive bonding (layer C). The doping concentration and thickness of each layer are shown in Table 2.

[0103] Table 2

[0104]

[0105] In Comparative Example 1, the N-terminal structure utilizes conventional titanium and gold (i.e., a 10 nm thick Ti layer and a 100 nm thick Au layer) as non-annealed metal electrodes for N-terminal metal contact. Figure 4a The current-voltage curves of the N-terminal formed in Comparative Example 1 at a temperature of 300K are shown. Figure 4a As shown, layer A on the surface of the film after transfer consists of: 1E19 layers / cm 3 The thickness of the Si-doped GaAs is 5 nm, with 1E19 atoms / cm. 3 Si-doped Al 0.2 Ga 0.8 The thickness of As is 5nm, with 2E18 particles / cm. 3 Si-doped Al 0.2 Ga 0.8 The thickness of As is 25 nm, and the total thickness of the doped layer is 35 nm. At this point, the Ti / Au combination still cannot produce a good ohmic contact, resulting in a current-voltage (IV) curve. The high doping concentration will lead to strong light absorption, affecting the collection efficiency of quantum dot fluorescence. Although this doping concentration is fully applicable to bulk samples, it is not applicable to thin films at all.

[0106] In Example 1, the N-terminal structure utilizes the Pd / Ge / Au (i.e., a 10nm thick Pd layer, a 35nm thick Ge layer, and a 100nm thick Au layer) of the present invention as a non-annealed metal electrode for N-terminal metal contact. Figure 4b The current-voltage curve of the N-terminal formed in Example 1 at a temperature of 300K is shown. Figure 4bAs shown, layer A on the surface of the film after transfer consists of: undoped GaAs with a thickness of 5 nm and 4E18 particles / cm. 3 The thickness of the Si-doped GaAs is 5 nm, with 4E18 atoms / cm. 3 The thickness of the Si-doped AlGaAs is 30 nm, and the thickness of the doped layer is 35 nm. It can be seen that when the doping concentration is reduced to 4E18 atoms / cm², the... 3 At the same time, this method also completes the fabrication of ohmic contacts, forming a straight IV orientation, which significantly suppresses the additional light absorption caused by free carriers. Meanwhile, the lower doping concentration also makes the device more stable.

[0107] Example 2:

[0108] Using molecular beam epitaxy, a second composite protective layer, an N-type semiconductor doped layer, a second intrinsic layer, a quantum dot layer, a first intrinsic layer, a P-type semiconductor doped layer, and a first composite protective layer of different thicknesses, as shown in Table 3, were sequentially grown on a 625 μm thick gallium arsenide substrate to obtain a quantum dot semiconductor structure. The quantum dot film was then transferred to a new 625 μm thick gallium arsenide substrate using adhesive bonding. First, SU8 2000.5 photoresist with a thickness of approximately 500 nm was spin-coated onto the new GaAs substrate. Then, the substrate was vacuum-heated to 220°C and pressurized to 0.02 MPa to bond with the quantum dot semiconductor structure and remove the original substrate, thus obtaining the quantum dot film.

[0109] The groove pattern on the P-side was exposed, and a second metal layer was etched and deposited using S1813 photoresist at a spin coating speed of 3000 rpm to a thickness of approximately 800 nm. Wet etching was then performed using a solution with a volume ratio of H₂SO₄:H₂O₂:H₂O of 4:4:200 at an etching rate of approximately 1 to 2 nm / s. The second metal layer was formed by sequentially depositing 10 nm of Ti and 100 nm of Au using electron beam evaporation, followed by stripping away the remaining metal.

[0110] The N-terminal groove pattern was exposed, and the first metal layer was etched and deposited using S1813 photoresist with a spin coating parameter of 3000 r / min and a thickness of approximately 800 nm. Then, a wet etching solution with a volume ratio of H2SO4:H2O2:H2O = 4:4:200 was used at an etching rate of approximately 1 to 2 nm / s. Pd was deposited sequentially at a thickness of 10 nm, Ge at 35 nm, and Au at 100 nm using electron beam evaporation to form the first metal layer. The remaining metal was then removed by stripping to obtain the sample.

[0111] The sample was placed on a hot plate at 180°C and heated for 60 minutes in an atmospheric atmosphere, then cooled to room temperature to obtain the annealed sample. The upper surface of the annealed sample was selectively passivated using atomic layer deposition to deposit approximately 5 nm of Al2O3 to protect the annealed sample from oxidation. Then, a wet etching solution with a volume ratio of H2SO4:H2O2:H2O = 4:4:200 was used to etch for 10 seconds to remove the Al2O3 from the metal electrodes (which can be the first metal electrode and the second metal electrode) formed by the first metal layer and the second metal layer, respectively.

[0112] By encapsulating the aforementioned sample with leads, one end of an aluminum wire can be attached to the first and second metal electrodes using silver paste, while the other end is connected to an electrode of the same polarity leading to the power source, thereby completing the fabrication of an electrically regulated thin-film quantum dot light source.

[0113] Table 3

[0114]

[0115] The performance of the sample formed in Example 2 was tested. Figure 5a The current-voltage curve of the N-terminus of the sample formed in Example 2 at a temperature of 300K is shown. Figure 5b The current-voltage curve of the P-terminus of the sample formed in Example 2 at a temperature of 300K is shown. Figure 5c The current-voltage curve of the PN junction of the sample formed in Example 2 at a temperature of 300K is shown. Figure 5d The current-voltage curves of the PN junction of the sample formed in Example 2 at a low temperature of 6K are shown. Figures 5a-5d As shown, at room temperature (300K), the contact resistance between the N-terminal and N-terminal metal electrodes is approximately 1300 ohms, and the contact resistance between the P-terminal and P-terminal metal electrodes is approximately 10000 ohms, with a PN junction turn-on voltage of approximately 1.3V. When the sample was placed in a cryostat, the PN junction turn-on voltage was measured to be approximately 1.7V at a low temperature of 6K. This indicates that the sample exhibits good PN junction characteristics at both room temperature and low temperature.

[0116] Application Example 1:

[0117] The samples prepared in Example 2 were subjected to band-characterization spectral testing using continuous light at 532 nm. Figure 6a The spectrum of quantum dot 1-1 characterized by continuous light at 532 nm is shown in Application Example 1. Figure 6b The spectrum of quantum dots 1-2 characterized by continuous light at 532 nm is shown in Application Example 1. Figure 6c The spectrum of quantum dots 1-3 characterized using continuous light at 532 nm in Application Example 1 is shown. Figures 6a-6cAs shown, some exciton states disappear and others reappear with changes in voltage, indicating that the sample has an exciton state modulation effect. Simultaneously, the quantum dot signal blue shifts with increasing voltage; and for quantum dots of different wavelengths, i.e., for quantum dots of different volumes, this structure can achieve the Stark effect, thus enabling wavelength modulation. At different voltages, when the sample exceeds the low-temperature turn-on voltage of 1.7V, the quantum dots essentially stop emitting light, and the fluorescence signal exhibits a packet-like pattern rather than a single-line signal.

[0118] Comparative Example 2:

[0119] The preparation process of Comparative Example 2 is largely the same as that of Example 2, except that the thickness of the first intrinsic layer is adjusted to 60 nm to prepare the sample.

[0120] Comparative application example 1:

[0121] The sample prepared in Comparative Example 2 was subjected to band-based spectral characterization using continuous light at 532 nm. Figure 7a The spectrum of quantum dot 2-1 characterized by continuous light at 532 nm is shown in Comparative Application Example 1. Figure 7b The spectrum of quantum dot 2-2 characterized using continuous light at 532 nm in Comparative Application Example 1 is shown. Figure 7a and Figure 7b As shown, and with Figures 6a-6c By comparison, it can be seen that as the thickness of the intrinsic layer decreases, the wavelength of the quantum dots changes more significantly with voltage. Figure 7a and Figure 7b The Stark coefficient of the sample in the sample is compared to Figures 6a-6c The sample has a large Stark coefficient. However, at this point, from a negative voltage to the PN junction turning on, it can be seen that all the exciton states present in the quantum dot do not appear or disappear with the change of voltage, and the exciton state regulation function is basically lost.

[0122] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrically tunable thin-film quantum dot light source, characterized in that, The electrically controlled thin-film quantum dot light source comprises, from bottom to top, a first substrate, a first composite protective layer, a P-type semiconductor doped layer, a first intrinsic layer, a quantum dot layer, a second intrinsic layer, an N-type semiconductor doped layer, and a second composite protective layer; A first metal layer and a second metal layer are disposed in a first groove that penetrates the second composite protective layer and a portion of the N-type semiconductor doped layer, and the first metal layer is in contact with the N-type semiconductor doped layer; the second metal layer is disposed in a second groove that penetrates the second composite protective layer, the N-type semiconductor doped layer, the second intrinsic layer, the quantum dot layer, the first intrinsic layer and a portion of the P-type semiconductor doped layer, and the second metal layer is in contact with the P-type semiconductor doped layer. The quantum dot layer includes at least one group III-V semiconductor quantum dot; The thickness of the first intrinsic layer is greater than that of the second intrinsic layer, so that it can respond to the external electric field applied to the first metal layer and the second metal layer to form a bias electric field acting on the III-V semiconductor quantum dot, thereby regulating the exciton states of holes and electrons generated after the III-V semiconductor quantum dot is photoexcited, and regulating the wavelength of fluorescence generated by the recombination of holes and electrons.

2. The electrically regulated thin-film quantum dot light source according to claim 1, characterized in that, The thickness ratio of the first intrinsic layer to the second intrinsic layer is (3~6):1; and / or, The thickness of the first intrinsic layer is 150~200 nm; The thickness of the second intrinsic layer is 20~40nm.

3. The electrically regulated thin-film quantum dot light source according to claim 1, characterized in that, The material of the first metal layer includes at least one of palladium, germanium, or gold; The material of the second metal layer includes at least one of titanium or gold.

4. The electrically tunable thin-film quantum dot light source according to any one of claims 1 to 3, characterized in that, The materials of the first intrinsic layer and the second intrinsic layer each independently include one of the following: gallium arsenide, aluminum arsenide, and aluminum gallium arsenide; The quantum dot layer is made of at least one of the following: gallium arsenide, aluminum gallium arsenide, indium arsenide, indium gallium arsenide, and indium phosphide; The materials of the N-type semiconductor doped layer include at least one of the following: N-type doped gallium arsenide, N-type doped aluminum arsenide, and N-type doped aluminum gallium arsenide; The materials for the P-type semiconductor doped layer include at least one of the following: P-type doped gallium arsenide, P-type doped aluminum arsenide, and P-type doped aluminum gallium arsenide.

5. The electrically tunable thin-film quantum dot light source according to any one of claims 1 to 3, characterized in that, The thickness of the first composite protective layer is 30~60nm; The thickness of the doped layer in a P-type semiconductor is 30~50 nm; The thickness of the quantum dot layer is 6~10nm; The thickness of the N-type semiconductor doped layer is 30~50nm; The thickness of the second composite protective layer is 30~60nm.

6. The electrically tunable thin-film quantum dot light source according to any one of claims 1 to 3, characterized in that, The first and second composite protective layers are independently arranged from the vicinity of the quantum dot layer to the distance from the quantum dot layer, and include: a gallium arsenide aluminum layer, a gallium arsenide layer, and an aluminum oxide layer.

7. The electrically tunable thin-film quantum dot light source according to any one of claims 1 to 3, characterized in that, The first substrate includes any one of gallium arsenide, single-crystal silicon, and lithium niobate; The first substrate and the first composite protective layer are connected by adhesive bonding or molecular bonding.

8. A method for preparing an electrically tunable thin-film quantum dot light source according to any one of claims 1 to 7, characterized in that, The preparation method includes: A second composite protective layer, an N-type semiconductor doped layer, a second intrinsic layer, a quantum dot layer, a first intrinsic layer, a P-type semiconductor doped layer, and a first composite protective layer are sequentially formed on the second substrate to form a quantum dot semiconductor structure on the second substrate. The quantum dot semiconductor structure is transferred onto the first substrate by means of adhesive bonding or molecular bonding. The second composite protective layer is etched down to the N-type semiconductor doped layer to form the first groove, and a first metal layer is deposited in the first groove; The sample is obtained by etching from the second composite protective layer to the P-type semiconductor doped layer to form the second groove, and depositing the second metal layer in the second groove. The sample was annealed, and wires were drawn from the first metal layer and the second metal layer respectively to obtain an electrically tunable thin-film quantum dot light source. The annealing temperature is 160~200℃.

9. A method of using an electrically tunable thin-film quantum dot light source as described in any one of claims 1 to 7, characterized in that, include: Using a regulated power supply, the exciton states of at least one group III-V semiconductor quantum dot of the electrically controlled thin-film quantum dot light source under different voltages are determined under the first photoexcitation, and the target voltage corresponding to the target exciton state is determined. Using a DC voltage consistent with the target voltage, at least one III-V semiconductor quantum dot of an electrically controlled thin-film quantum dot light source is resonantly excited under the second photoexcitation to obtain a single photon or an entangled photon pair. The wavelength of the second photoexcitation is greater than the wavelength of the first photoexcitation.

10. The method of use according to claim 9, characterized in that, The voltage of the regulated power supply is 0.2~1.7V.

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