An electrically pumped zero-threshold near-infrared laser and a manufacturing method thereof

Abstract

The present invention relates to an electrically pumped zero-threshold near-infrared laser and a manufacturing method thereof, which includes a dielectric substrate (1), an indium tin oxide distributed feedback grating layer (2), an electron transport layer (3), a mercury telluride quantum dot layer (4), a hole transport layer (5), and a positive electrode layer (6) stacked in sequence from bottom to top; based on the power supply from an external power source, and the mercury telluride quantum dot layer (4) is composed of mercury telluride quantum dots each rich in surface states. The electrons and holes injected from the electron transport layer (3) and the hole transport layer (5) into the mercury telluride quantum dot layer (4) will quickly relax from the band-edge states of the mercury telluride quantum dots to the lower-energy surface states, that is, there is a strong surface state emission transition in the mercury telluride quantum dots, which excites the mercury telluride quantum dots and realizes zero-threshold near-infrared light gain through surface state emission. Furthermore, the indium tin oxide distributed feedback grating layer (2) provides optical feedback to efficiently obtain electrically pumped, zero-threshold, and high-emission-intensity near-infrared laser light.

Description

Technical Field

[0001] The present invention relates to an electrically pumped zero-threshold near-infrared laser and a manufacturing method thereof, belonging to the technical field of semiconductor optoelectronic devices. Background Art

[0002] Near-infrared lasers can be widely applied in fields such as optical communication, remote sensing, and coherent plasma generation. Benefiting from the quantum confinement effect, semiconductor quantum dots exhibit various excellent properties as optical gain materials. However, due to the multiple degeneracy of the band-edge states, for the band-edge states of quantum dots to achieve optical gain, the number of excitons contained therein must be greater than half of the degeneracy of the lowest quantum state participating in the emission. For example, for lead selenide quantum dots with an 8-fold degeneracy of the lowest quantum state, the number of excitons in each quantum dot on average must exceed 4 to achieve population inversion. This not only limits the optical gain threshold of quantum dots but also severely restricts the optical gain lifetime because multi-exciton Auger recombination is very efficient, making it difficult to achieve continuous optical pumping or electrical pumping of laser emission. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an electrically pumped zero-threshold near-infrared laser, which can efficiently obtain near-infrared laser with electrical pumping, zero threshold, and high emission intensity through a new structural design.

[0004] The present invention adopts the following technical solutions to solve the above technical problems: The present invention designs an electrically pumped zero-threshold near-infrared laser, including a dielectric substrate, an indium tin oxide distributed feedback grating layer, an electron transport layer, a mercury telluride quantum dot layer, a hole transport layer, and a positive electrode layer, which are stacked in sequence from bottom to top;

[0005] Among them, the mercury telluride quantum dot layer includes mercury telluride quantum dots each rich in surface states, and the surface state emission is located in the near-infrared wavelength. The resonant wavelength of the indium tin oxide distributed feedback grating layer is the same as the surface state emission peak wavelength of the mercury telluride quantum dots in the mercury telluride quantum dot layer; Based on taking power by using the indium tin oxide distributed feedback grating layer as the negative electrode layer and connecting the positive electrode layer to a power supply, the electron transport layer and the hole transport layer inject electrons and holes into the mercury telluride quantum dot layer respectively, exciting the mercury telluride quantum dots serving as the optical gain medium in the mercury telluride quantum dot layer, achieving zero-threshold near-infrared optical gain through surface state emission, and then the indium tin oxide distributed feedback grating layer provides optical feedback for the optical gain medium to obtain near-infrared laser, which is emitted from the lower surface of the dielectric substrate.

[0006] As a preferred technical solution of the present invention: The mercury telluride quantum dots each rich in surface states in the mercury telluride quantum dot layer are distributed according to a preset density.

[0007] As a preferred technical solution of the present invention: The hole transport layer is a triamine layer composed of 4-carbazol-9-ylphenyl.

[0008] As a preferred technical solution of the present invention: the thickness of the hole transport layer is 10 nanometers.

[0009] As a preferred technical solution of the present invention: the electron transport layer is a titanium dioxide layer.

[0010] As a preferred technical solution of the present invention: the dielectric substrate is an aluminum oxide substrate.

[0011] As a preferred technical solution of the present invention: the positive electrode layer is a gold layer.

[0012] Correspondingly, the technical problem to be solved by the present invention is to provide a manufacturing method for obtaining an electrically pumped zero-threshold near-infrared laser, and through a specifically designed process design flow, efficiently obtain the manufacturing of the designed near-infrared laser.

[0013] The present invention adopts the following technical solutions to solve the above technical problems: The present invention designs a manufacturing method for obtaining an electrically pumped zero-threshold near-infrared laser, including the following steps:

[0014] Step A. Using the colloidal method, by controlling the reaction time, prepare mercury telluride quantum dots with surface state emissions located in the near-infrared wavelength, and disperse them in toluene to obtain a mercury telluride quantum dot toluene dispersion;

[0015] Step B. Repeat the following operation a preset number of times to obtain a target toluene dispersion including mercury telluride quantum dots rich in surface states;

[0016] Operation: Add acetone to the mercury telluride quantum dot toluene dispersion, then perform centrifugation to obtain a precipitate, and then disperse the precipitate in fresh toluene to update the mercury telluride quantum dot toluene dispersion;

[0017] Step C. Using magnetron sputtering, deposit an indium tin oxide thin film on the dielectric substrate;

[0018] Step D. Using reactive ion etching, etch the indium tin oxide thin film to obtain an indium tin oxide distributed feedback grating layer;

[0019] Step E. Spin-coat titanium dioxide ethanol sol on the upper surface of the indium tin oxide distributed feedback grating layer to construct an electron transport layer;

[0020] Step F. Spin-coat the target toluene dispersion on the upper surface of the electron transport layer, and anneal the target toluene dispersion to construct a mercury telluride quantum dot layer;

[0021] Step G. Using thermal evaporation, deposit a triamine layer composed of 4-carbazol-9-ylphenyl on the upper surface of the mercury telluride quantum dot layer to construct a hole transport layer;

[0022] Step H. Deposit a gold layer on the upper surface of the hole transport layer by thermal evaporation to construct a positive electrode layer.

[0023] As a preferred technical solution of the present invention: in the step F, the target toluene dispersion is spin-coated on the upper surface of the electron transport layer, and the target toluene dispersion is annealed in an inert gas environment to construct a mercury telluride quantum dot layer.

[0024] The electric pump zero-threshold near-infrared laser and manufacturing method thereof according to the present invention, compared with the prior art by adopting the above technical solutions, have the following technical effects:

[0025] (1) The electric pump zero-threshold near-infrared laser and manufacturing method designed by the present invention include a dielectric substrate, an indium tin oxide distributed feedback grating layer, an electron transport layer, a mercury telluride quantum dot layer, a hole transport layer, and a positive electrode layer stacked in sequence from bottom to top; powered by an external power supply, and the mercury telluride quantum dot layer is composed of mercury telluride quantum dots each rich in surface states. The electrons and holes injected from the electron transport layer and the hole transport layer into the mercury telluride quantum dot layer will quickly relax from the band-edge states of the mercury telluride quantum dots to the lower-energy surface states, that is, there is a strong surface state emission transition in the mercury telluride quantum dots, exciting the mercury telluride quantum dots, and realizing near-infrared light gain with zero threshold by surface state emission. Furthermore, the indium tin oxide distributed feedback grating layer provides optical feedback to efficiently obtain near-infrared laser with electric pump, zero threshold, and high emission intensity;

[0026] (2) In the electric pump zero-threshold near-infrared laser designed by the present invention, since the optical gain of the mercury telluride quantum dots rich in surface states in the mercury telluride quantum dot layer is single-exciton optical gain, its optical gain lifetime is not limited by rapid multi-exciton Auger recombination, but is determined by the surface state single-exciton lifetime of the mercury telluride quantum dots rich in surface states, and the surface state single-exciton lifetime of the mercury telluride quantum dots rich in surface states is on the order of microseconds, and the gain relaxation is much slower than the electric pump rate and the laser establishment time. Therefore, the zero-threshold near-infrared laser emission of electric pump is efficiently realized;

[0027] (3) In the electric pump zero-threshold near-infrared laser designed by the present invention, for the layout of the mercury telluride quantum dots each rich in surface states in the mercury telluride quantum dot layer, a distribution layout design is carried out according to a preset density, that is, through the close-packed layout of the mercury telluride quantum dots, the net mode gain of the mercury telluride quantum dot layer can be improved, which is beneficial to improving the laser emission intensity; and while designing the positive electrode layer for power taking, it is designed that the positive electrode layer enhances the emission intensity of the surface states through plasma resonance, thereby increasing the emission intensity of the near-infrared laser, and the positive electrode layer can improve the output intensity of the near-infrared laser on the lower surface of the dielectric substrate by reflection;

[0028] (4) In the electro-pumped zero-threshold near-infrared laser designed by the present invention, the triamine layer composed of 4-carbazol-9-ylphenyl serves as a hole transport layer, which can act as a spatial spacer layer between the mercury telluride quantum dot layer and the positive electrode layer to prevent the rapid non-radiative transfer of energy from the mercury telluride quantum dots to the positive electrode layer. Moreover, the design of a 10-nanometer thickness can effectively prevent non-radiative energy transfer while achieving strong plasmon resonance. Description of the Drawings

[0029] Figure 1 is a schematic structural diagram of the electro-pumped zero-threshold near-infrared laser of the present invention;

[0030] Figure 2 is a schematic energy level diagram of the mercury telluride quantum dots in the mercury telluride quantum dot layer of the present invention.

[0031] Among them, 1. dielectric substrate, 2. indium tin oxide distributed feedback grating layer, 3. electron transport layer, 4. mercury telluride quantum dot layer, 5. hole transport layer, 6. positive electrode layer. Specific Embodiments

[0032] The following further elaborates on the specific embodiments of the present invention with reference to the accompanying drawings of the specification.

[0033] The present invention designs an electro-pumped zero-threshold near-infrared laser. In practical applications, as Figure 1 shown, it includes a dielectric substrate 1, an indium tin oxide distributed feedback grating layer 2, an electron transport layer 3, a mercury telluride quantum dot layer 4, a hole transport layer 5, and a positive electrode layer 6 that are sequentially stacked from bottom to top.

[0034] Among them, the mercury telluride quantum dot layer 4 includes mercury telluride quantum dots that are rich in surface states and whose surface state emissions are located in the near-infrared wavelength. The resonance wavelength of the indium tin oxide distributed feedback grating layer 2 is the same as the wavelength of the surface state emission peak of the mercury telluride quantum dots in the mercury telluride quantum dot layer 4.

[0035] Based on the indium tin oxide distributed feedback grating layer 2 constituting the negative electrode layer and combined with the positive electrode layer 6 connecting to a power source to draw electricity, the electron transport layer 3 and the hole transport layer 5 respectively inject electrons and holes into the mercury telluride quantum dot layer 4. These electrons and holes will quickly relax from the conduction band edge states of the mercury telluride quantum dots to the lower-energy surface states, that is, there is a strong surface state emission transition in the mercury telluride quantum dots, exciting the mercury telluride quantum dots serving as the optical gain medium in the mercury telluride quantum dot layer 4, achieving zero-threshold near-infrared optical gain through surface state emission. Furthermore, the indium tin oxide distributed feedback grating layer 2 provides optical feedback for the optical gain medium to obtain near-infrared laser, which is emitted from the lower surface of the dielectric substrate 1.

[0036] Such as Figure 2As shown, since there is no absorption transition in the surface states of mercury telluride quantum dots in the mercury telluride quantum dot layer 4, the mercury telluride quantum dots only emit light without absorption at the emission wavelength of the surface states. The energy of the emission comes from the transfer of the band-edge states. The population of mercury telluride quantum dots rich in surface states is transparent to light with the same wavelength as the emission wavelength of the surface states in the unexcited state, that is, there is neither absorption nor emission. As long as one mercury telluride quantum dot in the mercury telluride quantum dot layer 4 is excited, and then electrons and holes relax to the surface states (the surface states contain an exciton), optical gain is formed at the emission wavelength of the surface states. Therefore, near-infrared optical gain with zero threshold can be achieved using mercury telluride quantum dots rich in surface states. More importantly, since the optical gain of mercury telluride quantum dots rich in surface states is single-exciton optical gain, its optical gain lifetime is not limited by fast multi-exciton Auger recombination, but is determined by the surface-state single-exciton lifetime of mercury telluride quantum dots rich in surface states. And the surface-state single-exciton lifetime of mercury telluride quantum dots rich in surface states is on the order of microseconds, and the gain relaxation is much slower than the electrical pumping rate and the laser build-up time. With a suitable cavity structure, electrically pumped near-infrared laser emission with zero threshold can be achieved.

[0037] Based on the above-designed electrically pumped near-infrared laser with zero threshold, the mercury telluride quantum dots rich in surface states in the mercury telluride quantum dot layer 4 are further designed to be distributed according to a preset density, that is, through the close-packed layout of mercury telluride quantum dots, the net mode gain of the mercury telluride quantum dot layer 4 can be increased, which is beneficial to increasing the laser emission intensity.

[0038] In the actual application of the above-mentioned electrically pumped near-infrared laser with zero threshold, the triamine layer composed of 4-carbazol-9-ylphenyl is designed as the hole transport layer 5, which can act as a spatial spacer layer between the mercury telluride quantum dot layer 4 and the positive electrode layer 6 to prevent the rapid non-radiative transfer of energy from the mercury telluride quantum dots to the positive electrode layer 6. And the design of a 10-nanometer thickness can ensure effective hindrance of non-radiative energy transfer while achieving strong plasmon resonance; in addition, in actual specific applications, the electron transport layer 3 is designed as a titanium dioxide layer; the dielectric substrate 1 is designed as an aluminum oxide substrate; while the positive electrode layer 6 is designed for taking electricity, the positive electrode layer 6 enhances the emission intensity of the surface states through plasmon resonance, thereby increasing the emission intensity of the near-infrared laser, and the positive electrode layer 6 can increase the output intensity of the near-infrared laser on the lower surface of the dielectric substrate 1 through reflection. In the implementation, the positive electrode layer 6 is designed as a gold layer.

[0039] In order to actually obtain the above-mentioned electrically pumped near-infrared laser with zero threshold, the present invention specifically designs a manufacturing method. In actual applications, the following steps A to H are specifically implemented.

[0040] Step A. Using the colloid method, by controlling the reaction time, prepare mercury telluride quantum dots with surface-state emissions located in the near-infrared wavelength, and disperse them in toluene to obtain a mercury telluride quantum dot toluene dispersion.

[0041] Step B. Repeat the following operations for a preset number of times to obtain a target toluene dispersion liquid containing mercury telluride quantum dots rich in surface states;

[0042] Operation: Add acetone to the toluene dispersion liquid of mercury telluride quantum dots, then perform centrifugation to obtain a precipitate, and then disperse the precipitate in fresh toluene to update the toluene dispersion liquid of mercury telluride quantum dots;

[0043] Step C. Deposit an indium tin oxide thin film on the dielectric substrate 1 by magnetron sputtering;

[0044] Step D. Etch the indium tin oxide thin film by reactive ion etching to obtain an indium tin oxide distributed feedback grating layer 2;

[0045] Step E. Spin-coat the titanium dioxide ethanol sol on the upper surface of the indium tin oxide distributed feedback grating layer 2 to construct an electron transport layer 3;

[0046] Step F. Spin-coat the target toluene dispersion liquid on the upper surface of the electron transport layer 3 and anneal the target toluene dispersion liquid in an inert gas environment to construct a mercury telluride quantum dot layer 4;

[0047] Step G. Deposit a triamine layer composed of 4-carbazol-9-ylphenyl on the upper surface of the mercury telluride quantum dot layer 4 by thermal evaporation to construct a hole transport layer 5;

[0048] Step H. Deposit a gold layer on the upper surface of the hole transport layer 5 by thermal evaporation to construct a positive electrode layer 6.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An electrically pumped zero-threshold near-infrared laser, characterized in that: It includes a dielectric substrate (1), an indium tin oxide distributed feedback grating layer (2), an electron transport layer (3), a mercury telluride quantum dot layer (4), a hole transport layer (5), and a positive electrode layer (6) which are stacked in sequence from bottom to top; Among them, the mercury telluride quantum dot layer (4) includes mercury telluride quantum dots each rich in surface states and with surface state emission at near-infrared wavelengths. The resonant wavelength of the indium tin oxide distributed feedback grating layer (2) is the same as the wavelength of the surface state emission peak of the mercury telluride quantum dots in the mercury telluride quantum dot layer (4). Based on using the indium tin oxide distributed feedback grating layer (2) as the negative electrode layer and connecting the positive electrode layer (6) to a power supply to draw electricity, the electron transport layer (3) and the hole transport layer (5) respectively inject electrons and holes into the mercury telluride quantum dot layer (4), exciting the mercury telluride quantum dots serving as the optical gain medium in the mercury telluride quantum dot layer (4) to achieve near-infrared optical gain with zero threshold through surface state emission. Then, the indium tin oxide distributed feedback grating layer (2) provides optical feedback for the optical gain medium to obtain near-infrared laser, which is emitted from the lower surface of the dielectric substrate (1); The mercury telluride quantum dots each rich in surface states in the mercury telluride quantum dot layer (4) are distributed and arranged according to a preset density; the positive electrode layer (6) is a gold layer.

2. The electrically pumped zero-threshold near-infrared laser according to claim 1, wherein: The hole transport layer (5) is a triamine layer composed of 4-carbazol-9-ylphenyl.

3. The electrically pumped zero-threshold near-infrared laser according to claim 2, characterized in that: The thickness of the hole transport layer (5) is 10 nanometers.

4. The electrically pumped zero-threshold near-infrared laser according to claim 1, characterized in that: The electron transport layer (3) is a titanium dioxide layer.

5. The electrically pumped zero-threshold near-infrared laser according to claim 1, wherein: The dielectric substrate (1) is an aluminum oxide substrate.

6. A manufacturing method of an electrically pumped zero-threshold near-infrared laser as claimed in claim 1, characterized in that, It includes the following steps: Step A. Using the colloid method, by controlling the reaction time, prepare mercury telluride quantum dots with surface state emission at near-infrared wavelengths and disperse them in toluene to obtain a mercury telluride quantum dot toluene dispersion; Step B. Repeat the following operation a preset number of times to obtain a target toluene dispersion including mercury telluride quantum dots each rich in surface states; Operation: Add acetone to the mercury telluride quantum dot toluene dispersion, then perform centrifugation to obtain a precipitate, and then disperse the precipitate in fresh toluene to update and obtain the mercury telluride quantum dot toluene dispersion; Step C. Using magnetron sputtering, deposit an indium tin oxide thin film on the dielectric substrate (1); Step D. Using reactive ion etching, etch the indium tin oxide thin film to obtain the indium tin oxide distributed feedback grating layer (2); Step E. Spin-coat titanium dioxide ethanol sol on the upper surface of the indium tin oxide distributed feedback grating layer (2) to construct the electron transport layer (3); Step F. Spin-coat the target toluene dispersion on the upper surface of the electron transport layer (3) and anneal the target toluene dispersion to construct the mercury telluride quantum dot layer (4); Step G. Using thermal evaporation, deposit a triamine layer composed of 4-carbazol-9-ylphenyl on the upper surface of the mercury telluride quantum dot layer (4) to construct the hole transport layer (5); Step H. Using thermal evaporation, deposit a gold layer on the upper surface of the hole transport layer (5) to construct the positive electrode layer (6).

7. The manufacturing method of an electrically pumped zero-threshold near-infrared laser according to claim 6, characterized in that: In the said step F, based on spin-coating the target toluene dispersion on the upper surface of the electron transport layer (3), anneal the target toluene dispersion in an inert gas environment to construct the mercury telluride quantum dot layer (4).

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