Preparation method of band-gap-adjustable alloy nanowire and wavelength-tunable laser

Abstract

The invention discloses a preparation method of an alloy nanowire with an adjustable band gap and a wavelength tunable laser, and the method comprises the steps: 1) mixing CdS powder and CdSe powder according to a molar ratio to form a precursor; 2) putting the precursor at the central position of a heating area of a tubular heating furnace; 3) depositing a catalyst on the surface of the substrate through a plasma sputtering process to obtain a catalytic substrate; 4) placing the catalytic substrate in a downstream area of a heating area of a tubular heating furnace; (5) argon is introduced into the tubular heating furnace from the upstream area of the heating area at a constant flow speed, and air is discharged from the downstream area; (6) the tubular heating furnace is heated, and argon is continuously introduced; and (7) melting the catalyst on the catalytic substrate into liquid pellets, transmitting precursor evaporated CdS / CdSe steam to the surface of the catalytic substrate and dissolving the precursor evaporated CdS / CdSe steam into the liquid pellets, and generating the alloy nanowire under the action of saturated crystallization. The laser comprises an alloy nanowire and a glass substrate. The ultra-wide wavelength tunable nano laser developed by the invention is simple in structure and wide in wavelength tunable range.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a method for preparing alloy nanowires with tunable bandgap and a wavelength-tunable laser. Background Technology

[0002] Semiconductor nanolasers are devices that realize optical amplification and laser emission at the nanoscale. Nanowires serve as the gain medium and optical resonator of semiconductor nanolasers, and their fabrication technology is the key to the development of semiconductor nanolasers. However, existing methods still face some challenges in terms of bandgap tuning and photoluminescence performance.

[0003] Thanks to their small size, low cost, and low power consumption, semiconductor nanolasers have seen rapid development in applications such as optical communication, high-density data storage, solid-state lighting, and sensing. In particular, wide-band wavelength-tunable nanowire lasers offer new and interesting opportunities and broad application prospects for on-chip optoelectronic integration, super-resolution imaging, and cell labeling / tracking. Currently, methods for achieving wavelength-tunable semiconductor nanowire lasers mainly include: constructing multi-quantum-well core / shell heterostructures and controlling the synthesis process of alloy semiconductor nanowires; using stepwise cutting of nanowires or adjusting the vertical coupling points between nanowires to induce absorption-emission-reabsorption effects; or controlling the plasmon-enhanced Burstein-Moss effect by changing the dielectric layer thickness and temperature. However, these methods often rely on precise micro / nano manipulation, complex control systems, or operation at low temperatures, placing high demands on device fabrication and practical applications. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing alloy nanowires with tunable bandgap and a wavelength-tunable laser.

[0005] The technical solution adopted to achieve the technical objective of this invention is as follows: a method for preparing alloy nanowires with adjustable bandgap, comprising the following steps:

[0006] 1) Mix CdS powder and CdSe powder in a molar ratio to form a precursor.

[0007] 2) Place the precursor in the center of the heating zone of the tubular furnace.

[0008] 3) A catalyst is deposited on the substrate surface by plasma sputtering to obtain a catalytic substrate.

[0009] 4) Place the catalytic substrate in the downstream region of the heating zone of the tubular furnace.

[0010] 5) Argon gas is introduced into the tubular furnace from the upstream region of the heating zone at a constant flow rate, and air is discharged from the downstream region.

[0011] 6) The heating tube furnace is continuously supplied with argon gas.

[0012] 7) The catalyst on the catalytic substrate melts into liquid spheres, and the CdS / CdSe vapor evaporated from the precursor is transported to the surface of the catalytic substrate and dissolved in the liquid spheres, forming alloy nanowires under saturated crystallization.

[0013] Furthermore, the molar ratio is x:(1-x), where x is a real number and 0≤x≤1.

[0014] Furthermore, the tubular heating furnace includes a quartz tube furnace and adopts a closed design.

[0015] Furthermore, the substrate includes a silicon substrate.

[0016] Furthermore, the catalyst is made of materials including gold.

[0017] Furthermore, alloy nanowires prepared with different molar ratios exhibit different bandgap characteristics.

[0018] Within a fixed wavelength range, the wavelength of the laser emitted by the alloy nanowires can be adjusted by selecting cavity lengths of different alloy nanowire lengths.

[0019] Furthermore, in step 3), the step of obtaining the catalytic substrate is as follows:

[0020] 3.1) Clean the substrate surface.

[0021] 3.2) Place the cleaned substrate into the gold plating machine and set the gold plating time.

[0022] 3.3) Vacuum is drawn inside the gold plating machine, and a catalyst is deposited on the substrate surface using a plasma sputtering coating process to obtain a catalytic substrate.

[0023] Furthermore, after the alloy nanowires are generated, they are separated from the catalytic substrate. Separation methods include mechanical exfoliation and fiber optic probe micromanipulation transfer.

[0024] A wavelength-tunable laser includes: alloy nanowires and a glass substrate prepared by the above method.

[0025] The alloy nanowires serve as the gain medium and resonant cavity.

[0026] The alloy nanowires are placed on a glass substrate.

[0027] Furthermore, alloy nanowires prepared in different molar ratios are assembled into nanowire arrays and placed on a glass substrate.

[0028] The technical effects of this invention are undeniable. This invention discloses a method for preparing cadmium sulfide selenide semiconductor alloy nanowires with tunable bandgap and realizing an ultrawideband wavelength-tunable nanolaser. Based on chemical vapor deposition, this method involves heating a silicon substrate with a uniformly mixed cadmium sulfide / sulfide selenide powder and a deposited metal thin film in separate sections. By adjusting the mixing ratio and heating temperature, a large quantity of alloy semiconductor nanowires with controllable bandgap and excellent photoluminescence performance is obtained. Furthermore, combining nanowire bandgap tuning and the optical self-feedback mechanism of intrinsic self-absorption in the gain medium, a nanowire laser operating at room temperature with a tunable wavelength range covering 510–678 nm is successfully fabricated by controlling the composition of the semiconductor alloy and the cavity length of the laser resonator. This laser possesses wide-band wavelength tuning capability and is suitable for various applications such as sensors, biological cell laser probes, and optical communication systems. This invention has significant advantages such as simple fabrication process, flexible bandgap tuning, and a wide laser wavelength tuning range.

[0029] This invention utilizes a chemical vapor deposition method, which is simple and efficient, allowing for effective control of the growth direction and length of semiconductor nanowires. This results in the production of large quantities of cadmium sulfide selenide semiconductor alloy nanowires with varying band gaps, exhibiting excellent photoluminescence properties. The ultrawide wavelength tunable nanolaser developed in this invention has a simple structure and a wide tunable wavelength range. Attached Figure Description

[0030] Figure 1 Schematic diagram of a semiconductor alloy nanowire growth apparatus with adjustable bandgap;

[0031] Figure 2 These are typical electron microscopy and energy dispersive spectroscopy (EDS) images of alloy semiconductor nanowires. Figure 2 (a) is a typical electron micrograph of CdS nanowires; Figure 2 (b) is a typical CdS 0.7 Se 0.3 Electron micrograph of alloy nanowires; Figure 2 (c) is a typical CdS, CdS 0.8 Se 0.2 CdS 0.7 Se 0.3 CdS 0.5 Se 0.5 CdS 0.3 Se 0.7 Energy spectrum of CdSe nanowires;

[0032] Figure 3 A schematic diagram of the laser emission wavelength of a semiconductor nanowire laser that combines composition and cavity length modulation; Figure 3 (a) is a schematic diagram of the laser emission wavelength for nanowires with CdS fixed composition; Figure 3 (b) For CdS 0.8 Se0.2 A schematic diagram of the laser emission wavelength of nanowires with fixed composition; Figure 3 (c) For CdS 0.5 Se 0.5 A schematic diagram of the laser emission wavelength of nanowires with fixed composition; Figure 3 (d) is a schematic diagram of the laser emission wavelength for nanowires with CdSe fixed composition;

[0033] Figure 4 Schematic diagram of an ultrawide wavelength controllable nanolaser; Figure 4 (a) is a schematic diagram of the principle of a wavelength-tunable array nanowire laser; Figure 4 (b) Schematic diagram of obtaining laser output in different wavelengths by moving the pump region of the 473nm laser. Detailed Implementation

[0034] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0035] Example 1:

[0036] See Figures 1 to 4 A method for preparing alloy nanowires with tunable bandgap includes the following steps:

[0037] 1) Mix CdS powder and CdSe powder in a molar ratio to form a precursor.

[0038] 2) Place the precursor in the center of the heating zone of the tubular furnace.

[0039] 3) A catalyst is deposited on the substrate surface by plasma sputtering to obtain a catalytic substrate.

[0040] 4) Place the catalytic substrate in the downstream region of the heating zone of the tubular furnace.

[0041] 5) Argon gas is introduced into the tubular furnace from the upstream region of the heating zone at a constant flow rate, and air is discharged from the downstream region.

[0042] 6) The heating tube furnace is continuously supplied with argon gas.

[0043] 7) The catalyst on the catalytic substrate melts into liquid spheres, and the CdS / CdSe vapor evaporated from the precursor is transported to the surface of the catalytic substrate and dissolved in the liquid spheres, forming alloy nanowires under saturated crystallization.

[0044] Example 2:

[0045] A method for preparing alloy nanowires with adjustable bandgap is described in Example 1. Further, the molar ratio is x:(1-x), where x is a real number and 0≤x≤1.

[0046] Example 3:

[0047] A method for preparing alloy nanowires with adjustable bandgap, the main technical contents of which are described in any one of Examples 1 to 2, further wherein the tubular heating furnace includes a quartz tube furnace and adopts a closed design.

[0048] Example 4:

[0049] A method for preparing alloy nanowires with adjustable bandgap, the main technical contents of which are described in any one of Examples 1 to 3, further wherein the substrate includes a silicon substrate.

[0050] Example 5:

[0051] A method for preparing alloy nanowires with adjustable bandgap, the main technical contents of which are described in any one of Examples 1 to 4, and further, the catalyst is made of gold.

[0052] Example 6:

[0053] A method for preparing alloy nanowires with adjustable bandgap is described in any one of Examples 1 to 5. Furthermore, alloy nanowires prepared with different molar ratios have different bandgap characteristics.

[0054] Within a fixed wavelength range, the wavelength of the laser emitted by the alloy nanowires can be adjusted by selecting cavity lengths of different alloy nanowire lengths.

[0055] Example 7:

[0056] A method for preparing alloy nanowires with tunable bandgap, the main technical contents of which are described in any one of Examples 1 to 6, further comprising the following steps in step 3) for obtaining the catalytic substrate:

[0057] 3.1) Clean the substrate surface.

[0058] 3.2) Place the cleaned substrate into the gold plating machine and set the gold plating time.

[0059] 3.3) Vacuum is drawn inside the gold plating machine, and a catalyst is deposited on the substrate surface using a plasma sputtering coating process to obtain a catalytic substrate.

[0060] Example 8:

[0061] A method for preparing alloy nanowires with tunable bandgap is provided, the main technical contents of which are described in any one of Examples 1 to 7. Further, after the alloy nanowires are generated, they are separated from the catalytic substrate. Separation methods include mechanical exfoliation and fiber optic probe micromanipulation transfer.

[0062] Example 9:

[0063] A wavelength-tunable laser comprises: alloy nanowires and a glass substrate prepared by the method described in any one of Examples 1 to 8.

[0064] The alloy nanowires serve as the gain medium and resonant cavity.

[0065] The alloy nanowires are placed on a glass substrate.

[0066] Example 10:

[0067] A wavelength-tunable laser, the main technical contents of which are described in Example 9, further wherein alloy nanowires prepared in different molar ratios are assembled to form a nanowire array and placed on a glass substrate.

[0068] Example 11:

[0069] See Figures 1 to 4 A method for preparing alloy nanowires with tunable bandgap includes the following steps:

[0070] 1) Mix CdS powder and CdSe powder in a molar ratio to form a precursor.

[0071] 2) Place the precursor in the alumina boat and place the alumina boat in the center of the heating zone of the tubular furnace.

[0072] 3) A catalyst is deposited on the substrate surface by plasma sputtering to obtain a catalytic substrate.

[0073] 4) Place the catalytic substrate in the downstream region of the heating zone of the tubular furnace.

[0074] 5) Argon gas is introduced into the tubular furnace from the upstream region of the heating zone at a constant flow rate, and air is discharged from the downstream region.

[0075] Before the reaction begins, 500 sccm of high-purity argon gas is introduced into the system to remove residual air, and the cleaning time is 2 hours.

[0076] 6) The heating tube furnace is continuously supplied with argon gas.

[0077] 7) The catalyst on the catalytic substrate melts into liquid spheres, and the CdS / CdSe vapor evaporated from the precursor is transported to the surface of the catalytic substrate and dissolved in the liquid spheres, forming alloy nanowires under saturated crystallization.

[0078] The furnace temperature was raised from room temperature to 850°C under a pressure of 200 mbar over 20 minutes and maintained at this temperature for 1 hour. An argon flow rate of 200 sccm was maintained throughout the heating process to deliver the evaporated CdS / CdSe vapor to the gold-catalyzed silicon substrate surface to promote nanowire growth. The local temperature at the substrate was approximately 650°C, and the growth time was 1 hour. Finally, yellow to orange-red CdS was observed on the silicon substrate surface. x Se 1-x Alloy nanowire products. Alloy nanowires with CdS x Se 1-x The component ratio is mainly determined by the ratio of CdS and CdSe mixed powders. Therefore, by adjusting the component ratio of the precursor powder, the band gap of the final alloy nanowire can be effectively controlled.

[0079] The alloy semiconductor obtained by saturation crystallization can be in the form of sheets or blocks, and macroscopic conditions such as growth temperature can be used to ensure that the precipitated crystals are linear.

[0080] Example 12:

[0081] A method for preparing alloy nanowires with adjustable bandgap is described in Example 11. Further, the molar ratio is x:(1-x), where x = 1, 0.8, 0.7, 0.5, 0.3, 0.

[0082] Example 13:

[0083] A method for preparing alloy nanowires with adjustable bandgap, the main technical contents of which are described in any one of Examples 11 to 12, further wherein the tubular heating furnace includes a quartz tube furnace and adopts a closed design.

[0084] Example 14:

[0085] A method for preparing alloy nanowires with adjustable bandgap, the main technical contents of which are described in any one of Examples 11 to 13, further wherein the substrate includes a silicon substrate.

[0086] Example 15:

[0087] A method for preparing alloy nanowires with adjustable bandgap, the main technical contents of which are described in any one of Examples 11 to 14, and further, the catalyst is made of gold.

[0088] Example 16:

[0089] A method for preparing alloy nanowires with adjustable bandgap is described in any one of Examples 11 to 15. Furthermore, alloy nanowires prepared with different molar ratios have different bandgap characteristics.

[0090] Within a fixed wavelength range, the wavelength of the laser emitted by the alloy nanowires can be adjusted by selecting cavity lengths of different alloy nanowire lengths.

[0091] When the length of the CdS semiconductor nanowire increases from 17 μm to 68 μm, the wavelength of the laser emitted from the nanowire is adjustable between 511 nm and 519 nm.

[0092] When CdS 0.8 Se 0.2 When the length of the semiconductor nanowire increases from 7μm to 38μm, the wavelength of the laser emitted from the nanowire is adjustable between 548nm and 562nm.

[0093] When CdS 0.5 Se 0.5 When the length of the semiconductor nanowire increases from 7μm to 42μm, the wavelength of the laser emitted from the nanowire is adjustable between 608nm and 626nm.

[0094] When the length of the CdSe semiconductor nanowire increases from 9 μm to 45 μm, the wavelength of the laser emitted from the nanowire is adjustable between 659 nm and 676 nm.

[0095] Example 17:

[0096] A method for preparing alloy nanowires with tunable bandgap, the main technical contents of which are described in any one of Examples 11 to 16, further comprising the following steps in step 3) for obtaining the catalytic substrate:

[0097] 3.1) Clean the substrate surface.

[0098] 3.2) Place the cleaned substrate into the gold plating machine and set the gold plating time.

[0099] 3.3) Vacuum is drawn inside the gold plating machine, and a catalyst is deposited on the substrate surface using a plasma sputtering coating process to obtain a catalytic substrate.

[0100] Example 18:

[0101] A method for preparing alloy nanowires with tunable bandgap is provided, the main technical contents of which are described in any one of Examples 11 to 17. Further, after the alloy nanowires are generated, they are separated from the catalytic substrate. Separation methods include mechanical exfoliation and fiber optic probe micromanipulation transfer.

[0102] Example 19:

[0103] A wavelength-tunable laser comprises: alloy nanowires prepared by the method of any one of Examples 11 to 18 and a MgF2 substrate.

[0104] The alloy nanowires serve as the gain medium and resonant cavity.

[0105] The alloy nanowires are placed on a MgF2 substrate.

[0106] Example 20:

[0107] A wavelength-tunable laser, the main technical contents of which are described in Example 19, further wherein alloy nanowires prepared in different molar ratios are assembled to form a nanowire array and placed on a MgF2 substrate.

[0108] By splicing and synergistic output of multi-component nanowires, complementary effects are formed between different wavelength bands, ultimately achieving wavelength-tunable laser output covering the range of 510nm–678nm, demonstrating excellent broadband control capability.

[0109] Example 21:

[0110] See Figures 1 to 4 A method for preparing alloy nanowires with tunable bandgap and a wavelength-tunable laser, the main technical contents of which include:

[0111] (1) Tunable bandgap semiconductor alloy nanowires were synthesized via gold-catalyzed chemical vapor deposition (CVD). For example... Figure 1 As shown, the entire growth process was carried out in a quartz tube furnace with single-temperature zone heating. The specific steps are as follows: First, CdS and CdSe powders mixed in a molar ratio (x:1-x) were placed in an alumina boat as a precursor and positioned at the center of the heating zone as an evaporation source. Using a silicon wafer as a substrate, a gold film of approximately 10 nm thickness was deposited on its surface as a catalyst via plasma sputtering. This catalytic substrate was placed in the downstream low-temperature region near the end of the heating zone for nanowire growth. Before the reaction began, 500 sccm of high-purity argon gas was introduced into the system to remove residual air for 2 hours. Subsequently, the furnace temperature was raised from room temperature to 850 °C at a pressure of 200 mbar over 20 minutes and maintained at this temperature for 1 hour. Throughout the heating process, an argon gas flow rate of 200 sccm was maintained to transport the evaporated CdS / CdSe vapor to the surface of the gold-catalyzed silicon substrate to promote nanowire growth. The local temperature at the substrate was approximately 650 °C, and the growth time was 1 hour. Finally, yellow to orange-red CdS can be observed on the silicon substrate surface. x Se 1-x Alloy nanowire products. Alloy nanowires with CdS x Se 1-x The component ratio is mainly determined by the ratio of CdS and CdSe mixed powders. Therefore, by adjusting the component ratio of the precursor powder, the band gap of the final alloy nanowire can be effectively controlled.

[0112] (2) To realize an ultrawideband wavelength-tunable nanowire laser, this paper selects six different compositions of CdS x Se 1-x Alloy nanowires (x = 1, 0.8, 0.7, 0.5, 0.3, 0) can effectively expand their emission wavelength coverage by precisely controlling the component ratios. Each component of the nanowire has a different bandgap characteristic, with fluorescence emission peaks spaced approximately 30-50 nm apart, each corresponding to an independent laser emission band. Within the fixed wavelength range corresponding to each component, by selecting different nanowire cavity lengths and combining this with the optical self-feedback mechanism induced by the intrinsic self-absorption of the gain medium, continuous tuning of the laser within a single wavelength band can be achieved. Furthermore, by utilizing the splicing and synergistic output of multi-component nanowires, complementary effects are formed between different wavelength bands, ultimately achieving wavelength-tunable laser output covering the 510–678 nm range, demonstrating excellent broadband control capabilities.

[0113] Example 22:

[0114] See Figures 1 to 4 A method for preparing alloy nanowires with tunable bandgap and a wavelength-tunable laser, the main technical contents of which include:

[0115] 1. Preparation of semiconductor alloy nanowires with tunable bandgap

[0116] Alloy nanowires were prepared using gold-catalyzed chemical vapor deposition (CVD). Silicon wafers were used as the substrate for nanowire growth, and a gold film approximately 10 nm thick was deposited on the silicon substrate surface as a catalyst. First, single-sided polished monocrystalline silicon wafers were cut and their surfaces cleaned. Then, the cleaned silicon wafers underwent gold plating: the cut wafers were placed in a gold plating machine, the plating time was set to 90 seconds, and after vacuuming, an Au film of approximately 10 nm thickness was prepared on the silicon wafer using plasma sputtering. The coated silicon substrates were then placed entirely within one end of a quartz tube in a tubular furnace, ensuring that the substrates were positioned in the downstream low-temperature region near the end of the heating zone. The diagram of the alloy nanowire growth apparatus is shown below. Figure 1 As shown. After the preparation work is completed, cadmium sulfide and cadmium selenide powders are uniformly mixed at molar ratios of 1:0, 8:2, 7:3, 5:5, 3:7, and 0:1 respectively as precursors. The mixed powder is placed in an alumina boat, which is then placed in a quartz tube in a tubular furnace, ensuring that the alumina boat is positioned in the center of the heating zone of the tubular furnace as an evaporation source.

[0117] Ensure all valves are tightly closed. Open the vacuum valve and start the vacuum pump to continuously reduce the pressure inside the quartz heating tube until it reaches the lowest vacuum level. Once the pressure inside the tube stabilizes, introduce high-purity argon gas at a flow rate of 500 sccm into the system. This removes residual air and prevents chemical reactions with airborne substances during substrate heating and crystallization, which could interfere with the results. Continue this cleaning process for 2 hours. After removing residual air, adjust the argon inlet valve to change its inlet flow rate to 200 sccm. This allows the CdS / CdSe vapor from the evaporation source to be transported to the gold-catalyzed silicon substrate surface in the downstream low-temperature region near the end of the heating zone, promoting the growth of alloy nanowires. Maintaining the inlet flow rate at 200 sccm and the tube pressure at 200 mbar, turn on the tubular furnace and set the furnace parameters as follows: heating time 20 min, isothermal time 60 min, and preset heating temperature 850℃. The program is started, and the tubular furnace rapidly heats to 850°C within the set time of 20 minutes, maintaining this temperature for 60 minutes. The local temperature at the silicon substrate is approximately 650°C. This temperature allows the Au film to melt and agglomerate into dispersed Au spherical droplets, and also facilitates the efficient deposition and dissolution of the alloy vapor transported to the substrate by Ar gas into the Au spherical droplets, leading to saturated crystallization. The saturated Au spherical droplets are then pushed upwards in the same direction by the crystallized alloy, resulting in densely packed alloy nanowires. After heating, the Ar gas inlet valve, vacuum valve, and vacuum pump are closed. The device is allowed to cool naturally to room temperature. The valves are then opened, and the silicon wafer is removed. Yellow to orange-red CdS can be observed on the silicon substrate surface. x Se 1-x The alloy nanowire product was obtained by placing the removed silicon wafer in a new petri dish and sealing it. (Alloy nanowires CdS) x Se 1-x The component ratio is mainly determined by the ratio of CdS and CdSe mixed powders. Therefore, by adjusting the component ratio of the precursor powder, the band gap of the final alloy nanowire can be effectively controlled.

[0118] CdS with different components prepared x Se 1-x Typical electron micrographs of alloy nanowires are shown below. Figure 2 As shown in (ab), the grown nanowires are thin, long, and generally straight, exhibiting good physical morphology with smooth end faces. Six different CdS compositions were also observed. x Se 1-x Energy Dispersive Spectrum (EDS) of alloy nanowires (x = 1, 0.8, 0.7, 0.5, 0.3, 0) as follows: Figure 2As shown in (c), the Si peak in the EDS diagram originates from the silicon substrate supporting the nanowires. The results show that the cadmium selenide ratio in the obtained nanowires basically matches the molar ratio of the mixed powder. This method can accurately control the ratio of cadmium sulfide and cadmium selenide in the nanowires, resulting in high crystal quality.

[0119] 2. Wavelength-tunable single nanowire laser devices

[0120] First, clean the MgF2 sheet with alcohol to remove dust and other impurities from its surface. After drying the MgF2 sheet, grow the four different CdS4 fractions. x Se 1-x Alloy nanowires (x = 1, 0.8, 0.5, 0) were placed on a MgF2 sheet using a mechanical exfoliation method. Then, at room temperature, a 473 nm nanosecond laser was used as the pump source. The microscope stage was horizontally adjusted to select CdS nanowires of different lengths from each composition that exhibited high luminous efficiency, regular shapes, and similar diameters. x Se 1-x (x = 1, 0.8, 0.5, 0) nanowires were used to characterize their photoluminescence properties (PL) using a spectrometer. Figure 3 (ad)).

[0121] Figure 3 (a) shows that when the length of the CdS semiconductor nanowire increases from 17 μm to 68 μm, the wavelength of the laser emitted from the nanowire is adjustable in the range of 511 nm to 519 nm. Figure 3 (b) shows that when CdS 0.8 Se 0.2 When the length of the semiconductor nanowire increases from 7 μm to 38 μm, the wavelength of the laser emitted from the nanowire is adjustable in the range of 548 nm to 562 nm. Figure 3 (c) Displays that when CdS 0.5 Se 0.5 When the length of the semiconductor nanowire increases from 7 μm to 42 μm, the wavelength of the laser emitted from the nanowire is adjustable in the range of 608 nm to 626 nm. Figure 3 (d) shows that when the length of the CdSe semiconductor nanowire increases from 9 μm to 45 μm, the wavelength of the laser emitted from the nanowire is adjustable from 659 nm to 676 nm.

[0122] In summary, the alloy nanowires of different compositions exhibit different bandgap characteristics, corresponding to an independent laser emission band. The fluorescence emission peaks of the different compositions are spaced approximately 30-50 nm apart. Within the fixed wavelength range corresponding to each composition, by selecting different nanowire cavity lengths and combining this with the optical self-feedback mechanism induced by the intrinsic self-absorption of the gain medium, continuous tuning of the laser within a single wavelength band can be achieved. Results show that the CdS prepared by this method...x Se 1-x Alloy nanowires have excellent laser emission performance, enabling splicing of different wavelengths with a wide range of adjustable wavelengths.

[0123] 3. Wavelength-tunable array nanowire laser devices

[0124] The laser structure was prepared from five different CdS compositions as described in Example 1. x Se 1-x The structure consists of an array of alloy nanowires (x = 1, 0.7, 0.5, 0.3, 0). This structure can be fabricated using the following method: After growing alloy nanowires with good physical morphology and high laser luminescence quality using gold-catalyzed chemical vapor deposition (CVD), the nanowires are separated from the substrate using a fiber optic probe. The separated nanowires are then placed on a MgF2 substrate that has been cleaned with alcohol and dried. The nanowires are first pumped with a 473nm laser. If the luminescence effect is good, micro- and nano-manipulation is performed under an optical microscope using a fiber optic probe. The nanowires are then assembled with other alloy nanowires of different compositions on the MgF2 substrate to form the nanowire array. The final device structure includes a MgF2 substrate and a CdSxSe1-x alloy nanowire array. By pumping different regions of the device with a 473nm laser, and based on the splicing and synergistic output of the multi-component nanowires, complementary effects are achieved between different wavelength bands, thus obtaining a wavelength-tunable laser device. The structure and its wavelength tuning results are shown below. Figure 4 As shown, this laser device ultimately achieves wavelength-tunable laser output covering the range of 510–678 nm, demonstrating excellent broadband control capabilities.

Claims

1. A method of fabricating a bandgap-tunable alloy nanowire, comprising: The method comprises the following steps: 1) mixing CdS powder and CdSe powder in a molar ratio to form a precursor; 2) placing the precursor in the center of a heating zone of a tube furnace; 3) depositing a catalyst on a substrate surface by a plasma sputtering process to obtain a catalytic substrate; 4) placing the catalytic substrate in a downstream area of the heating zone of the tube furnace; 5) introducing argon into the tube furnace from an upstream area of the heating zone at a constant flow rate, and discharging air from the downstream area; 6) heating the tube furnace and continuously introducing argon; 7) melting the catalyst on the catalytic substrate into liquid globules, and transmitting CdS / CdSe vapor evaporated from the precursor to the surface of the catalytic substrate and dissolving in the liquid globules to generate alloy nanowires under the action of saturation crystallization.

2. The method for preparing alloy nanowires with adjustable bandgap according to claim 1, characterized in that, The molar ratio is x:(1-x), wherein x is a real number and 0≤x≤1.

3. The method for preparing alloy nanowires with adjustable bandgap according to claim 1, characterized in that, The tube furnace comprises a quartz tube furnace and adopts a closed design.

4. The method for preparing alloy nanowires with adjustable bandgap according to claim 1, characterized in that, The substrate comprises a silicon substrate.

5. The method for preparing alloy nanowires with adjustable bandgap according to claim 1, characterized in that, The catalyst adopts gold.

6. The method of claim 1, wherein the alloy nanowire is a bandgap-tunable alloy nanowire. The alloy nanowires prepared in different molar ratios have different band gap characteristics. In a fixed waveband range, the length of the alloy nanowire cavity is selected to adjust the outgoing laser wavelength of the alloy nanowire.

7. The method of claim 1, wherein the alloy nanowire is a bandgap-tunable alloy nanowire. In step 3), the catalytic substrate is obtained by the following steps: A1 cleaning the substrate surface; A2 placing the cleaned substrate in a gold plating machine and setting the gold plating time of the gold plating machine; A3 vacuumizing the gold plating machine and depositing a catalyst on the substrate surface by a plasma sputtering film deposition process to obtain a catalytic substrate.

8. The method of claim 1, wherein the alloy nanowire is a bandgap-tunable alloy nanowire. After the alloy nanowires are generated, the alloy nanowires are separated from the catalytic substrate; the separation method comprises a mechanical peeling method and a fiber probe micro-operation transfer method.

9. A wavelength tunable laser, characterized by, The method comprises: alloy nanowires prepared by the method of any one of claims 1-8 and a glass substrate; the alloy nanowires as gain medium and resonant cavity; the alloy nanowires are placed on the glass substrate.

10. A wavelength tunable laser as claimed in claim 9, characterized in that, The alloy nanowires prepared in different molar ratios are assembled to form a nanowire array and placed on the glass substrate.

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