A Bandgap-Adjustable CdS 1-X Se X Nano-tripod laser and its preparation method

Abstract

A bandgap-tunable CdS 1‑X Se X nanotripod laser and its preparation method, belonging to the technical field of semiconductor material device preparation, can solve the problems that the existing preparation methods of bandgap-tunable lasers are costly and have limited application scope, which is not conducive to large-scale production. The present invention synthesizes a bandgap-tunable CdS 1‑X Se X nanotripod laser preparation method, and obtains a nanotripod semiconductor laser with three support lengths of 1-20 μm and diameters of 300-1000 nm. It has the advantages of easy operation, low cost, high yield, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material device preparation, and specifically relates to a bandgap adjustable CdS 1-X Se X Nano-tripod laser and its preparation method. Background Art

[0002] Nanotechnology is one of the main contents of scientific and technological research in various countries around the world. Nanotechnology is a highly interdisciplinary and comprehensive subject. The research content involves a wide range of modern science and technology. The research and application of nanotechnology are mainly in materials and preparation, microelectronics and computer technology, medicine and health, aerospace and aviation, environment and energy, biotechnology and agricultural products. Devices made of nanomaterials are lighter, longer lasting, lower cost and better performance. Nanomaterials, with their superior physical and chemical properties, have attracted widespread attention from the scientific and academic communities. Especially in new nanodevices, nanomaterials have shown important research value and broad prospects.

[0003] For the research history of semiconductor lasers, we can first trace back to 1916, when Einstein published the article "On the Quantum Theory of Radiation", which first proposed the theory of stimulated radiation and provided a theoretical basis for the development of lasers in the future. Then in May 1960, American scientist TH Maiman obtained the first laser beam in human history (length 0.6943 μm), and in July of the same year, he successfully developed the world's first laser (ruby pulse laser). Since the first laser beam was produced in 1960, lasers have had a profound impact on our daily lives and various fields of science and technology. In 2001, Professor Yang Peidong realized the ZnO nanowire laser for the first time, which opened up people's research on the frontier field of lasers - nanolasers. The field of nanolasers is the result of the interaction between the general field of nanotechnology or nanophotonics and semiconductor lasers. Nanolasers generally refer to micro lasers with a size equivalent to or smaller than the wavelength involved. The driving force behind the development of nanolasers and more general nanophotonics is the recognized size mismatch between silicon-based microelectronic devices and composite semiconductor-based optoelectronic devices. Nano-semiconductor lasers are currently a frontier research field in the fusion of nanotechnology (or nanophotonics) and semiconductor lasers.

[0004] Nano-semiconductor lasers have the advantages of small size (nanoscale), easy integration, high quality factor, single-mode laser emission, strong monochromaticity, high quantum efficiency, and high luminous efficiency. As demonstrated by Moore's Law in microelectronics, miniaturization and large-scale integration can lead to significant performance improvements and cost reductions. Take semiconductor nanowires as an example. It is a quasi-one-dimensional structure with a diameter of typically 10-100 nanometers and a length of 1-100 mm. Wires for optical applications are usually made of compound semiconductor materials of the III-V or II-VI groups. This growth is usually based on the so-called gas-liquid-solid mechanism, usually seeded with metal particles as catalysts. Since this metal wire exists in air after growth, the refractive index difference between the metal wire and the air is about 100%, that is, the refractive index difference divided by the average refractive index. In contrast, the relative refractive index contrast of GaAs / AlGaAs waveguides is only a few percentage points. The small size and high refractive index contrast of nanowires make them ideal candidates for nanolasers with large limiting factors. In addition, individual nanowires can serve as gain media and waveguides at the same time. This further ensures a large overlap of electronic and photonic modes, further increasing the confinement factor.

[0005] Another important advantage of nanowires as nanolasers is the wide range of available band gaps. Nanowires can be grown epitaxially, single crystals, or on any amorphous substrate. In the former case, nanowire growth is much more tolerant of lattice mismatch than planar epitaxial thin film growth. This allows for more growth material choices on a given substrate, and thus more available band gaps, compared to planar epitaxial technology. In the latter growth mode, the substrate is a simple mechanical support and can be any crystalline or amorphous substrate. This makes wavelength variation almost unlimited, and can be achieved by growing different materials or alloying different compound semiconductors, providing unprecedented advantages for laser applications. Since the first demonstration in 2001 that ZnO nanowires can be used as ultraviolet lasers, nanowire lasers based on various materials have been demonstrated to be used for different wavelengths, arrays, or single lasers under optical pumping. These advantages make it possible to realize nano semiconductor lasers with controllable band gap modulation.

[0006] Scientists have made great progress and achieved excellent results in the research of nanolasers with one-dimensional structures (such as wires, tubes, strips and rods). However, there are fewer studies on nanolasers with nano-tripod structures. 1-X Se X The research on nano-tripod lasers has not been reported in the existing literature. Summary of the invention

[0007] The preparation of bandgap-controlled lasers is achieved through traditional epitaxial growth techniques, size effects, and alloying, but due to its high cost and limited scope of use, it is not conducive to large-scale production. In the chemical vapor deposition (CVD) growth method, the growth of nanomaterials can produce nanomaterials with controllable polar or non-polar crystal orientations through catalyst particles as nucleation media, thereby affecting their optical and electronic properties, as well as the advantages of modulated doping and the synthesis of novel nanostructures. Because of its above advantages, it is an important method for growing nanomaterials. It also has the characteristics of low cost, easy operation, high yield, and large-scale production, which has attracted widespread attention from researchers.

[0008] In view of the shortcomings of the prior art, the present invention innovatively synthesizes a bandgap-adjustable CdS by CVD method. 1- X Se X The preparation method of nano-tripod laser obtained a nano-tripod semiconductor laser with three brackets of 1-20 μm in length and 300-1000 nm in diameter.

[0009] The present invention adopts the following technical solution:

[0010] A Bandgap-Adjustable CdS 1-X Se X The nano-tripod laser is a nano-tripod structure, wherein the nano-tripod structure is directly connected to the substrate near the center of the tripod, and three brackets grow upward from the center, wherein X takes a value of 0-1.

[0011] Furthermore, the three legs of the nano-tripod structure are single crystal structures of the same type with the same lattice spacing.

[0012] Furthermore, the nano-tripod laser has a length of 1-20 μm and a diameter of 300-1000 nm.

[0013] Furthermore, the CdS 1-X Se X Nano-tripod lasers, including all-component nano-tripod lasers from CdS to CdSe, with PL emission covering 509 nm~715 nm and transient stimulated emission luminescence of 520 nm~738 nm.

[0014] A Bandgap-Adjustable CdS 1-X Se X The preparation method of the nano-tripod laser comprises the following steps:

[0015] In the first step, nano-tin powder is placed in a ceramic boat with a length of 74 mm, marked as boat 1; CdS or CdSe or CdS / CdSe mixed chemicals are placed in a ceramic boat with a length of 74 mm, marked as boat 2; the intrinsic Si wafer cut in advance is placed in a ceramic boat with a length of 74 mm after ultrasonic treatment with deionized water and oven drying, marked as boat 3;

[0016] In the second step, the No. 2 boat obtained in the first step is pushed to the center of the heating furnace of the single-temperature tubular furnace, the No. 1 boat is pushed to between the air inlet and the No. 2 boat, which is located in the heating zone of the single-temperature tubular furnace, and the No. 3 boat is pushed to between the No. 2 boat and the air outlet, which is located in the sample deposition zone of the single-temperature tubular furnace;

[0017] The third step is to turn on the vacuum pump and introduce a trace amount of carrier gas for 40 minutes. The pressure control valve is in the maximum flux position. After that, the carrier gas flow rate is set and the pressure control valve is adjusted to stabilize it at a specific pressure. The entire single-temperature tubular furnace is heated to 780℃-800℃ within 30 minutes. After maintaining this temperature for 90 minutes, the heating is stopped and allowed to cool naturally to room temperature to obtain a nano-tripod laser.

[0018] Furthermore, the purity of all the chemicals described in the first step is ≧99.999%, the weight of the nano-tin powder in boat No. 1 is 0.035 g, the weight of the CdS or CdSe or CdS / CdSe mixed chemical in boat No. 2 is 0.07 g, and all the ceramic boats are washed with deionized water and dried in an oven before use.

[0019] Furthermore, the trace carrier gas in the third step is a trace amount of N 2 The carrier gas is 80 sccm. During the initial temperature rise, the carrier gas is set to 120 sccm. At the same time, the pressure control valve is adjusted to make the pressure in the tube furnace 220 Torr-225 Torr.

[0020] Furthermore, in the third step, the heating rate is 26°C / min, and the cooling rate is 4-7°C / min.

[0021] The beneficial effects of the present invention are as follows:

[0022] Chemical vapor deposition refers to the process of generating another solid material from a gaseous raw material through a certain chemical reaction under high temperature conditions. Compared with other methods for synthesizing bandgap-regulated semiconductor nanostructures, such as traditional molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD), this method has the advantages of simple process for preparing heterojunctions, easy operation, low experimental cost, and high sample yield. It is also suitable for preparing nanostructures of other physical forms, and crystal structures that can be prepared by CVD methods under various high temperature environments. The present invention utilizes the technology of changing the bandgap structure and physical form of the deposited material by changing the proportion of evaporation source content and the evaporation temperature of the catalyst, and at the same time utilizes precise control of pressure, growth temperature, airflow size, and change of solid reaction source chemicals to grow a nano-tripod structure with adjustable bandgap, and realizes a nano-tripod laser with adjustable bandgap and multi-band emission from 520nm to 738nm. This technology has the advantages of easy control, low cost, and high yield.

[0023] In the present invention, the pressure of growing the nano-tripod structure is 220 Torr-225 Torr, the gas flow rate is 120 sccm nitrogen, and the growth temperature is 780°C-800°C. The nano-tripod structure is obtained by precisely controlling these parameters and changing the material of the evaporation source. When the parameters are changed, the yield of the generated material will be reduced, and in severe cases, the corresponding nano-tripod structure will not be produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 CdS 1-X Se X Schematic diagram of the growth process of the nano-tripod structure;

[0025] Figure 2 High-magnification, low-magnification and single-root SEM images of the grown nano-tripod structure and stimulated emission luminescence images under 355 nm pulsed laser;

[0026] Figure 3 Microstructural characterization of the grown nano-tripod structures, element mapping, TEM images, lattice spacing analysis;

[0027] Figure 4 A single bright-field optical image of the grown nano-tripod structure, PL dark-field luminescence images at different positions, PL spectrum images, and optical mapping images;

[0028] Figure 5 The different components of CdS generated 1-X Se XOptical bright field image, PL dark field luminescence image, PL spectrum image and collected stimulated emission spectrum of the nano-tripod laser. DETAILED DESCRIPTION

[0029] The present invention discloses a CdS with adjustable bandgap 1-X Se X A nano-tripod laser, wherein the nano-tripod structure is directly connected to a substrate near the center of the tripod, and three supports grow obliquely upward from the center.

[0030] The present invention discloses a CdS with adjustable bandgap 1-X Se X Nano-tripod laser, each nano-tripod with a different chemical formula has a single crystal structure.

[0031] The present invention discloses a CdS with adjustable bandgap 1-X Se X Nano-tripod lasers can realize full-component nano-tripod lasers from CdS to CdSe, with PL emission covering 509 nm~715 nm and transient stimulated radiation emission of 520 nm~738 nm.

[0032] The present invention discloses a CdS with adjustable bandgap 1-X Se X The nano-tripod laser comprises the following steps (taking the preparation method of the pure component CdS nano-tripod laser as an example):

[0033] Step 1

[0034] Nano-tin powder with a purity of 99.999% was placed in a ceramic boat with a length of 74 mm, marked as boat 1; CdS with a purity of 99.999% was placed in a ceramic boat with a length of 74 mm, marked as boat 2. The intrinsic Si wafer cut in advance was placed in a ceramic boat with a length of 74 mm after ultrasonic treatment with deionized water and oven drying, marked as boat 3.

[0035] Step 2

[0036] Push boat No. 2 obtained in step 1 to the center of the single-temperature tubular furnace heating furnace, push boat No. 1 to between the air inlet and boat No. 2, and locate it within the heating zone of the single-temperature tubular furnace, push boat No. 3 to between boat No. 2 and the air outlet, and locate it within the sample deposition zone of the single-temperature tubular furnace.

[0037] Step 3

[0038] The vacuum pump was turned on and a trace amount of carrier gas was introduced for 40 min. At this time, the pressure did not need to be controlled and the pressure control valve was in the maximum flux position. After that, the carrier gas flow rate was set and the pressure control valve was adjusted to stabilize it at a specific pressure. The entire single-temperature tube furnace was heated to 780 °C within 30 min, and this temperature was maintained for 90 min before stopping heating and allowing it to cool naturally to room temperature to obtain a pure component CdS nano-tripod laser.

[0039] The present invention discloses a CdS with adjustable bandgap 1-X Se X Nano-tripod laser, the purity of all chemicals used in step 1 is ≥ 99.999%, the weight of nano-tin powder in boat No. 1 is 0.035g, and the weight of CdS in boat No. 2 is 0.07g. All ceramic boats are washed with deionized water and dried in an oven before preparation.

[0040] The present invention discloses a CdS with adjustable bandgap 1-X Se X Nano-triplet laser, in step 3, a trace amount of N was introduced for 40 min. 2 The carrier gas is 80 sccm. This step is to exhaust the air in the tube furnace. At the beginning of the temperature rise, the carrier gas is set to 120 sccm, and the pressure control valve is adjusted to make the pressure in the tube furnace about 220 Torr.

[0041] The present invention discloses a CdS with adjustable bandgap 1-X Se X Nano-tripod laser, in step 3, the heating rate used for heating is 26°C / min, and the cooling rate used is 4-7°C / min.

[0042] The present invention discloses a CdS with adjustable bandgap 1-X Se X Nano-triplet lasers, preparation of other CdS with different band gaps 1-X Se X The method of nano-tripod laser is similar to the above, the only difference is that the amount of chemicals weighed in boat 2 in step 1 is different. Mixing CdS and CdSe powders with different ratios can prepare alloy CdS with different band gaps. 1-X Se X Nano-triplet laser. Based on CdS 0.52 Se 0.48 For example, the mixed powder of CdS and CdSe has a total drug weight of 0.07g, which is 0.028gCdS and 0.042gCdSe respectively.

[0043] The present invention is suitable for preparing semiconductor materials with nanostructures in other physical forms.

[0044] Example 1

[0045] Preparation of pure CdS or pure CdSe nano-tripod lasers

[0046] The nano-tripod structure was grown by CVD method. All powder sources and reagents were purchased from AlfaAesar. The growth apparatus was as follows Figure 1 , consisting of a single-temperature tube furnace and two quartz tubes (one with a diameter of 50 mm and a length of 180 cm; the other with a diameter of 25 mm and a length of 90 cm). The short tube (length 90 cm) is placed in the long tube (length 180 cm). Before growth, two porcelain boats (length 74 mm) filled with CdS (or CdSe) powder (Alfa Aesar, 99.999%, 0.07 g) and Sn (Alfa Aesar, 99.999%, 0.035 g) powder were placed in the center and upstream of the heating zone, respectively. Several clean, intrinsic Si wafers of the same size were placed downstream of the gas flow to collect the deposited nanotriangle structures. Before heating, nitrogen (N 2 ) was introduced into the system at a rate of 80 sccm for 40 minutes to purge the air in the tube. -1 The temperature was heated to 780°C at a rate of 1.5°C while the pressure was fixed at 220 Torr. The growth time was 90 minutes. The carrier gas flow rate was set to 120 sccm while the temperature was increased. After the growth was completed, the temperature in the furnace was naturally cooled to room temperature, and the sample was taken out for characterization. The nano-tripods of other components were prepared using the same device, steps, and growth time. The difference lies in the growth temperature and pressure. For a schematic diagram of the specific growth process, please refer to Figure 1 .

[0047] Example 2

[0048] Preparation of CdS 0.52 Se 0.48 Nano-Tripod Laser

[0049] Similar to the experiment in implementation case 1, a single temperature tube test furnace is used as the heating experimental device ( Figure 1 ), Sn (Alfa Aesar, 99.999%, 0.035 g) powder as catalyst, nitrogen (N 2 ) as carrier gas, and the same intrinsic Si wafer as substrate to receive CdS in the gas 0.52 Se 0.48 Alloy material, evaporation source is CdS and CdSe mixed powder (Alfa Aesar, 99.999%, 0.028gCdS, 0.042gCdSe). Before heating, nitrogen (N 2 ) was introduced into the system at a rate of 80 sccm for 40 minutes to purge the air in the tube. -1The growth time was 90 min and the carrier gas flow rate was set to 120 sccm while the temperature was increased.

[0050] Table 1 shows the generated CdS with different components 1-X Se X Parameters of the nano-tripod laser, such as temperature, pressure, and airflow velocity.

[0051]

[0052] Figure 1 It is a schematic diagram of the device for growing the nano-tripod laser of the present invention, a single-temperature tube furnace and two quartz tubes, a tin source is placed at the edge of the furnace near the air inlet, a drug is placed at the center of the furnace, and a substrate is placed near the edge of the furnace near the air outlet.

[0053] Figure 2 The sample CdS obtained in the example 1-X Se X Structural analysis of the nano-tripod scanning electron microscope image; Scanning electron microscope (SEM) observations showed that the nano-tripod exhibited the unique morphology of the component compounds, with the three crystal scaffolds having a length of 1~8 μm and a diameter of 300~900 nm. Figure 2 It can be seen that the nano-tripod structure grows directly on the intrinsic silicon substrate. The part near the center of the tripod is directly connected to the substrate without any intermediate structure or buffer layer. The three brackets grow upward from the center. The growth of this structure on the substrate is not accidental. Figure 2 (b) shows its area-selective growth on a silicon substrate. Figure 2 (c) (d) are scanning electron microscope images of a single nano-tripod structure, where the polygonal cross-sections of the three scaffolds and the smooth crystalline edges can be clearly seen. Figure 2 (e) shows a colored top view of the nano-tripod structure grown on the original substrate under the excitation of a pulsed laser with a wavelength of 355 nm. It can be seen that the nano-tripod structure emits green light under excitation and the overall structure can be clearly observed. Figure 2 (f) is a color image of a single nano-tripod structure under pulsed laser excitation. Concentric green ripples reaching or even exceeding the excitation threshold can be seen at the ends of the three branches of the nano-tripod, indicating that the single nano-tripod structure is excited under this pulsed laser energy.

[0054] Figure 3 The sample CdS obtained in the example 1-X Se XTransmission electron microscopy (TEM) structural analysis of nano-tripods; The microstructure of these nano-tripods was studied. We used a homemade fiber taper to remove a single nano-tripod structure from the substrate and placed it on a copper grid for structural research and analysis. Figure 3 (a) shows a typical SEM-EDS image of a representative nano-tripod structure with a diameter of about 550 nm and a scaffold length of 3.8 μm. The collected in situ EDS spectra show that Cd, S, and Sn elements are present on the nano-tripod. In addition, it was found that these three elements are evenly distributed on the tripod structure, and the atomic content of Sn element is relatively small compared to S and Cd elements. The detailed spatial distribution of these elements was obtained by SEM-EDS elemental mapping, such as Figure 3 (b)-3(d) as shown. Figure 3 (e) is a typical bright field TEM image of the nano-tripod. In the image, we can see the clear central connection of the nano-tripod, the 120° projection angle between the three supports, and the straight and smooth edges. Figure 3 (g). Figure 3 (f) Figure 3 From the high-resolution transmission electron microscopy (HRTEM) image obtained in the red box in (e), we can see very good lattice arrangement without obvious defects, and the lattice spacing of the two legs is 0.352 nm, which is basically the same. Figure 3 (h) Figure 3 The HRTEM image of the boxed part in (g) also shows a lattice spacing of 0.352 nm, which can prove that the three legs are the same single crystal. Figure 3 The illustration in (h) is the selected area electron diffraction (SAED) pattern of the legs, which clearly shows that the diffraction spots are regularly arranged in rows and columns, which also proves the excellent single crystal nature of the nanotripod.

[0055] Figure 4 The sample CdS obtained in the example 1-X Se X Optical characterization image of the nano-tripod; the optical properties of this nano-tripod structure were tested and studied under an optical microscope (Olympus, BX53, F2). Figure 4 (a) is an optical bright field image of a nano-tripod with a side length of 2.5 μm and a diameter of 800 nm. The nano-tripod structure is excited by a continuous laser with a wavelength of 375 nm. Figure 4 (b)-(d) are optical dark-field photoluminescence images of the stent from the edge to different points (P1, P2, P3) in the center. The corresponding photoluminescence spectra collected are shown in Figure 2. Figure 4(f)-4(h). We can directly observe that under continuous laser excitation, the pure CdS nano-tripod emits green light due to spontaneous radiation, with a peak emission of 506 nm. In addition, the good waveguide effect of the nano-tripod structure can be observed in the dark field emission image, which shows that this structure may have a good quality optical confinement cavity. Figure 4 (e) is the optical mapping image of the nano-tripod structure. It can be seen that the luminescence images collected at different points under continuous laser excitation are consistent with the bright field image of the nano-tripod structure. The collection in the same wavelength range also shows that the three brackets of this structure have the same luminescence wavelength and are of the same crystal structure.

[0056] Figure 5 The sample CdS obtained in the example 1-X Se X Spontaneous emission of nano-tripod and corresponding stimulated emission spectra; In order to prove the universality of the growth mechanism of this nano-tripod laser, we replaced the chemicals in the solid reaction source during the growth process and synthesized representative alloy CdS with different components from pure CdS to pure CdSe. 1-X Se X Nano-tripod structure, and subjected to stimulated tests such as Figure 5 . Figure 5 (a)-(e) are CdS and CdS respectively. 0.83 Se 0.17 , CdS 0.52 Se 0.48 , CdS 0.33 Se 0.67 , optical bright field images and spontaneous emission dark field images of CdSe nano-tripod structures. The central peaks of the PL spectra collected by us for the tripod structures of alloys with different components are CdS (509nm), CdS 0.83 Se 0.17 (542nm), CdS 0.52 Se 0.48 (605nm), CdS 0.33 Se 0.67 (647nm), CdSe (710nm). We conducted stimulated emission tests on these structures and the results are as follows Figure 5 (f) These alloy nano-tripods all exhibit good stimulated properties. We collected these transient stimulated emission spectra and plotted the normalized intensity spectra. We can see that the main mode peaks of stimulated emission are CdS (520nm), CdS 0.83 Se 0.17 (560nm), CdS 0.52 Se 0.48 (628nm), CdS 0.33 Se 0.67(664nm)、CdSe(738nm)。

Claims

1. A bandgap-adjustable CdS 1-X Se X Nano-tripod laser, Features: The nano-tripod laser is a nano-tripod structure, and the nano-tripod structure is directly connected to the substrate near the center of the tripod, and three brackets grow upward from the center, wherein X takes a value of 0-1.

2. A bandgap adjustable CdS according to claim 1 1-X Se X Nano-tripod laser, Features: The three supports of the nano-tripod structure are single crystal structures of the same kind with the same lattice spacing.

3. The bandgap adjustable CdS according to claim 1 1-X Se X Nano-tripod laser, Features: The three supports of the nano-tripod laser have a length of 1-20 μm and a diameter of 300-1000 nm.

4. The bandgap adjustable CdS according to claim 1 1-X Se X Nano-tripod laser, Features: The CdS 1-X Se X Nano-tripod lasers, including all-component nano-tripod lasers from CdS to CdSe, with PL emission covering 509 nm~715 nm and transient stimulated emission luminescence of 520 nm~738 nm.

5. A Bandgap-Adjustable CdS 1-X Se X Preparation method of nano-tripod laser, Features: The steps include: In the first step, nano-tin powder is placed in a ceramic boat with a length of 74 mm, marked as boat 1; CdS or CdSe or CdS / CdSe mixed chemicals are placed in a ceramic boat with a length of 74 mm, marked as boat 2; the intrinsic Si wafer cut in advance is placed in a ceramic boat with a length of 74 mm after ultrasonic treatment with deionized water and oven drying, marked as boat 3; In the second step, the No. 2 boat obtained in the first step is pushed to the center of the heating furnace of the single-temperature tubular furnace, the No. 1 boat is pushed to between the air inlet and the No. 2 boat, which is located in the heating zone of the single-temperature tubular furnace, and the No. 3 boat is pushed to between the No. 2 boat and the air outlet, which is located in the sample deposition zone of the single-temperature tubular furnace; The third step is to start the vacuum pump and introduce a trace amount of carrier gas for 40 minutes. The pressure control valve is at the maximum flux position. After that, the carrier gas flow rate is set and the pressure control valve is adjusted to stabilize it at a specific pressure. The entire single-temperature tube furnace is heated to 780°C-800°C within 30 minutes. After maintaining this temperature for 90 minutes, the heating is stopped and allowed to cool naturally to room temperature to obtain a nano-tripod laser. The trace carrier gas in the third step is a trace amount of N 2 The carrier gas is 80 sccm. During the initial heating process, the carrier gas is set to 120 sccm. At the same time, the pressure control valve is adjusted to make the pressure in the tubular furnace 220 Torr-225 Torr.

6. The bandgap adjustable CdS according to claim 5 1-X Se X Preparation method of nano-tripod laser, Features: The purity of all the chemicals described in the first step is ≥ 99.999%, the weight of the nano-tin powder in boat No. 1 is 0.035 g, the weight of the CdS or CdSe or CdS / CdSe mixed chemical in boat No. 2 is 0.07 g, and all the ceramic boats are washed with deionized water and dried in an oven before use.

7. The bandgap adjustable CdS according to claim 5 1-X Se X Preparation method of nano-tripod laser, Features: The heating rate in the third step is 26°C / min, and the cooling rate is 4-7°C / min.

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