CN103043707A - Preparation method of perpendicular array ZnO nanowire - Google Patents

Abstract

The invention relates to a method for preparing ZnO nanowires in a vertical array, belonging to the field of nanowire preparation methods. The process steps of the method are as follows: (1) Preparation of precursor solution: add deionized water to the reaction vessel, then add zinc salt and polyethyleneimine, stir at room temperature and normal pressure for 0.5~3h to obtain the precursor solution; (2 ) Ultrafiltration: perform ultrafiltration on the precursor solution; (3) Spin coating: drop the solution intercepted in step (2) onto the substrate, and then apply the glue at a speed of 500~3000rpm; (4) Heat treatment: ① Apply the glue The finished substrate is kept at normal pressure, oxygen atmosphere, 400~600°C for 30~120min. After the holding time expires, the substrate is naturally cooled to room temperature. Keep it warm for 1-10 minutes. After the holding time expires, cool the substrate to room temperature naturally. ③Insulate the substrate treated in step ② under the conditions of 100-3000Pa, oxygen atmosphere, and 400-600℃ for 5-30 minutes.

Description

A kind of preparation method of vertical array ZnO nanowire

technical field

The invention belongs to the field of nanowire preparation methods, in particular to a preparation method of vertical array ZnO nanowires.

Background technique

Due to the unique size structure of nanomaterials, there are several effects different from traditional materials in the nanoscale range: surface effect, small size effect, quantum size effect and macroscopic quantum tunneling effect.

ZnO is a semiconductor material with a direct bandgap and a wide bandgap. At room temperature, its bandgap is 3.37eV, and its high exciton binding energy is about 60meV. One-dimensional ZnO nanomaterials have remarkable characteristics in optics, electrical transport, optoelectronics, piezoelectricity, electrodynamics, field emission, dilute magnetism, photocatalysis, and wave absorption. Electricity, energy, catalysis and other fields have shown good application prospects. Vertically arrayed ZnO nanowires are widely used in electronics, optoelectronics, and electromechanical nanodevices, such as solar cells, field emission devices, ultraviolet lasers, light-emitting diodes, and nanoengines.

The preparation methods of vertical array ZnO nanowires include metal-organic compound vapor deposition method, template-assisted deposition method and solid-liquid-gas epitaxy growth method. (1) Preparation process of vapor deposition of metal organic compounds: Diethyl zinc (Et ₂ Zn) and oxygen were used as reactants, and different gas flows were precisely controlled for the two, and the Si substrate was placed under the gas flow, at 400 Heat treatment at -500° C. for 5-60 minutes to obtain ZnO nanowires in a vertical array. This method has the disadvantage that the air flow is difficult to control. (2) The preparation process of the template-assisted deposition method: gold-plated on the porous anodized aluminum template, the gold-plated template is buckled upside down on the corundum boat equipped with the zinc source, and then put into the quartz tube together, in the argon atmosphere Heat to 800-900°C and react for 10 minutes to completely evaporate the Zn powder. At this time, stop feeding argon, start feeding oxygen to normal pressure, and wait until the temperature drops to room temperature to obtain ZnO nanowires in a vertical array. The disadvantages of this method are: ① gold plating operation is required on the template, which will introduce unnecessary impurities; ② the atmosphere conditions are difficult to control. (3) The preparation process of the solid-liquid-gas epitaxial growth method: firstly, it is necessary to plate gold on the substrate, coat a film, photolithography array pattern or select a suitable substrate, then place the substrate at the lower end of the gas flow, place the zinc source at the upper end of the gas flow, and place it in the argon gas Or prepare vertical array ZnO nanowires in the mixed gas of argon and oxygen. This method has the following disadvantages: ① It is necessary to plate gold or a film on the substrate to guide the growth of array nanowires. Selecting a suitable substrate, such as a GaN substrate, leads to high costs; ③ it is necessary to accurately control the atmosphere reaction conditions, and the required equipment is relatively expensive.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing vertically arrayed ZnO nanowires to simplify operations, improve controllability and reduce production costs.

The preparation method of the vertical array ZnO nanowires of the present invention, the process steps are as follows:

(1) Preparation of precursor solution

Add deionized water to the reaction vessel, then add zinc salt and polyethyleneimine, and stir at room temperature and normal pressure for 0.5~3h to obtain a precursor solution; the amount of the zinc salt, deionized water and polyethyleneimine is The mass ratio of zinc, deionized water, and polyethyleneimine in the zinc salt is limited to 1:400:20~1:80:4;

(2) ultrafiltration

The precursor solution obtained in step (1) is subjected to ultrafiltration, and the ultrafiltration time is limited to the fact that no liquid can be separated;

(3) Spin coating

Add the solution intercepted in step (2) onto the substrate dropwise at a speed of 200~1000rpm, and then apply glue at a speed of 500~3000rpm for 10~60s;

(4) heat treatment

①Insulate the glue-coated substrate obtained in step (3) under normal pressure, oxygen atmosphere, and 400-600°C for 30-120 minutes. After the holding time expires, cool the substrate naturally to room temperature.

②Insulate the substrate treated in step ① at normal pressure, oxygen atmosphere, and 800-1000°C for 1-10 minutes. After the holding time expires, naturally cool the substrate to room temperature.

③ Insulate the substrate treated in step ② under the conditions of 100~3000Pa, oxygen atmosphere, and 400~600°C for 5~30min.

In the above method, the zinc salt is zinc nitrate, zinc acetate or zinc chloride.

In the above method, the molecular weight cut-off of the ultrafiltration membrane used in the ultrafiltration operation is 400 ~ 10000 g/mol.

蓝宝石基底、蓝宝石基底、

蓝宝石基底、（111）硅基底中的任一种。In the above method, the substrate is a (0001) sapphire substrate,

sapphire base, sapphire base,

Any of sapphire substrate and (111) silicon substrate.

Compared with the prior art, the present invention has the following beneficial effects:

1. In the method of the present invention, the ultra-filtered precursor solution can be directly spin-coated on the substrate to perform heat treatment, and there is no need to plate gold or film on the substrate or plate gold on the template to guide the growth of array nanowires, which not only simplifies the operation , and will not introduce impurities, and can save costs.

2. The method of the present invention has wide adaptability to substrates, and there is no need to select a specific substrate according to the degree of lattice matching, which can save production costs.

3. The method of the present invention can realize the control of atmospheric conditions by using conventional equipment, and does not need to use expensive equipment to precisely control the atmospheric conditions, thus reducing production costs and facilitating industrialized production.

Description of drawings

Fig. 1 is the SEM photo of the vertical array ZnO nanowires prepared in embodiment 1 under magnification 10000 times;

Fig. 2 is the SEM photo of the vertical array ZnO nanowires prepared in embodiment 1 under magnification of 20000 times;

FIG. 3 is a SEM photo of the vertical array ZnO nanowires prepared in Example 1 under magnification of 100,000 times.

Detailed ways

The preparation method of the vertical array ZnO nanowires of the present invention will be further described through examples below. The purity of the zinc salt used in each of the following embodiments is all ≥ 99%, and the molecular weight of polyethyleneimine is 1000, and the purity is 99%; the high-temperature experimental furnace used in the following embodiments is provided by Tianjin Zhonghuan Experimental Electric Furnace Co., Ltd Production, the model is SK-G06163-2T.

Example 1

In this embodiment, the preparation method of vertical array ZnO nanowires is as follows:

(1) Preparation of precursor solution

Add 40g deionized water in reaction vessel, then add 2.275g zinc nitrate hexahydrate and 2g polyethyleneimine (the mass ratio of zinc in zinc nitrate hexahydrate, deionized water, polyethyleneimine is 1:80:4 ), stirred at a stirring speed of 2000 rpm for 2 h at room temperature and normal pressure to obtain a precursor solution;

(2) ultrafiltration

Add the precursor solution obtained in step (1) into an ultrafiltration centrifuge tube with a molecular weight cut-off of 10,000 g/mol, and then put the ultrafiltration centrifuge tube into a centrifuge for centrifugation at a speed of 3000 rpm. The ultrafiltration time is based on the fact that no liquid can be separated. limit;

(3) Spin coating

Put the (0001) sapphire substrate into the spin coating machine, drop the solution obtained by the ultrafiltration membrane intercepted in step (2) onto the (0001) sapphire substrate at a speed of 600rpm within 18s, and then apply glue at a speed of 2600rpm 30s;

(4) heat treatment

①Put the glue-coated substrate obtained in step (3) into a high-temperature experimental furnace, and vacuumize the furnace. When the pressure in the furnace reaches -0.095MPa, stop vacuuming, and then feed high-purity oxygen into the furnace to reach the pressure in the furnace. reach 0.03MPa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, keep the pressure in the furnace at normal pressure, heat the furnace to 500°C and keep the substrate at this temperature and normal pressure for 60 minutes, After the holding time expires, take out the substrate and cool it down to room temperature naturally, ② raise the temperature of the furnace to 900°C, put the substrate treated in step ① into the furnace, vacuum the furnace, and stop when the pressure in the furnace reaches -0.095MPa Vacuumize, then feed high-purity oxygen into the furnace until the pressure in the furnace reaches 0.03 MPa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, keep the pressure in the furnace at normal pressure, and place the substrate in the Atmospheric pressure and 900°C for 3 minutes. After the holding time expires, take out the substrate and cool it down to room temperature naturally. ③Reduce the furnace temperature to 500°C. Put the substrate treated in step ② into the furnace, and vacuum the furnace into the furnace Stop vacuuming when the pressure reaches -0.095MPa, then feed high-purity oxygen into the furnace until the pressure reaches -0.0922Pa, then use a mechanical pump to pump out the gas in the furnace while feeding high-purity oxygen into the furnace to keep the furnace The pressure is 2800Pa, and the substrate is kept at 2800Pa and 500° C. for 10 minutes. After the holding time expires, the substrate is taken out, and vertical arrays of ZnO nanowires are grown on the substrate. The SEM photos of the vertical array ZnO nanowires prepared in this embodiment at magnifications of 10000 times, 20000 times and 100000 times are shown in Figure 1, Figure 2 and Figure 3, respectively.

Example 2

In this embodiment, the preparation method of vertical array ZnO nanowires is as follows:

(1) Preparation of precursor solution

Add 40g of deionized water to the reaction vessel, then add 0.335g of zinc acetate and 2g of polyethyleneimine (the mass ratio of zinc in zinc acetate, deionized water, and polyethyleneimine is 1 : 400 : 20), at room temperature 1. Stir for 0.5h at a stirring speed of 2600 rpm under normal pressure to obtain a precursor solution;

(2) ultrafiltration

Add the precursor solution obtained in step (1) into an ultrafiltration centrifuge tube with a molecular weight cut-off of 400 g/mol, and then put the ultrafiltration centrifuge tube into a centrifuge for centrifugation at a speed of 1000 rpm. The ultrafiltration time is based on the fact that no liquid can be separated. limit;

(3) Spin coating

Put the (0001) sapphire substrate into the spin coater, add the solution intercepted by the ultrafiltration membrane in step (2) onto the (0001) sapphire substrate dropwise within 5s at a speed of 200rpm, and then apply glue at a speed of 500rpm 60s;

(4) heat treatment

①Put the glue-coated substrate obtained in step (3) into a high-temperature experimental furnace, and vacuumize the furnace. When the pressure in the furnace reaches -0.095MPa, stop vacuuming, and then feed high-purity oxygen into the furnace to reach the pressure in the furnace. reach 0.03MPa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, keep the pressure in the furnace at normal pressure, heat the furnace to 400°C and keep the substrate at this temperature and normal pressure for 120min, After the holding time expires, take out the substrate and cool it down to room temperature naturally. ②Raise the temperature of the furnace to 800°C, put the substrate treated in step ① into the furnace, vacuum the furnace, and stop when the pressure in the furnace reaches -0.095MPa Vacuumize, then feed high-purity oxygen into the furnace until the pressure in the furnace reaches 0.03MPa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, keep the pressure in the furnace as normal pressure, and place the substrate in the Atmospheric pressure and 800°C for 1min. After the holding time expires, take out the substrate and cool it down to room temperature naturally. ③Reduce the furnace temperature to 400°C. Put the substrate treated in step ② into the furnace, and vacuum the furnace into the furnace Stop vacuuming when the pressure reaches -0.095MPa, then feed high-purity oxygen into the furnace until the pressure in the furnace reaches -0.0949Pa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, and keep the pressure in the furnace at 100Pa, the substrate was incubated at 100Pa and 400° C. for 5 minutes. After the incubation time expired, the substrate was taken out, and vertical arrays of ZnO nanowires were grown on the substrate. The SEM photos of the vertical array ZnO nanowires prepared in this example are similar to those shown in Figures 1-3.

Example 3

In this embodiment, the preparation method of vertical array ZnO nanowires is as follows:

(1) Preparation of precursor solution

Add 40g deionized water in the reaction vessel, then add 1.042g zinc chloride and 2g polyethyleneimine (the mass ratio of zinc in the zinc chloride, deionized water, polyethyleneimine is 1: 80: 4), Stirring at room temperature and normal pressure for 3 hours at a stirring speed of 1000 rpm to obtain a precursor solution;

(2) ultrafiltration

Add the precursor solution obtained in step (1) into an ultrafiltration centrifuge tube with a molecular weight cut-off of 1000 g/mol, then put the ultrafiltration centrifuge tube into a centrifuge and centrifuge at a speed of 3000 rpm. The ultrafiltration time is based on the fact that no liquid can be separated. limit;

(3) Spin coating

Put the (111) silicon substrate into the spin coater, add the solution intercepted by the ultrafiltration membrane in step (2) onto the (111) silicon substrate dropwise at a speed of 1000rpm within 20s, and then apply glue at a speed of 3000rpm 10s;

(4) heat treatment

①Put the glue-coated substrate obtained in step (3) into a high-temperature experimental furnace, and vacuumize the furnace. When the pressure in the furnace reaches -0.095MPa, stop vacuuming, and then feed high-purity oxygen into the furnace to reach the pressure in the furnace. reach 0.03MPa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, keep the pressure in the furnace at normal pressure, heat the furnace to 600°C and keep the substrate at this temperature and normal pressure for 30 minutes, After the holding time expires, take out the substrate and cool it down to room temperature naturally, ② raise the temperature of the furnace to 1000°C, put the substrate treated in step ① into the furnace, vacuum the furnace, and stop when the pressure in the furnace reaches -0.095MPa Vacuumize, then feed high-purity oxygen into the furnace until the pressure in the furnace reaches 0.03 MPa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, keep the pressure in the furnace at normal pressure, and place the substrate in the Atmospheric pressure, 1000°C for 10 minutes, after the holding time expires, take out the substrate and cool it down to room temperature naturally, ③Reduce the furnace temperature to 600°C, put the substrate treated in step ② into the furnace, and evacuate the furnace into the furnace Stop vacuuming when the pressure reaches -0.095MPa, then feed high-purity oxygen into the furnace until the pressure in the furnace reaches -0.092Pa, then discharge the gas in the furnace while feeding high-purity oxygen into the furnace, and keep the pressure in the furnace at 3000Pa, the substrate was kept at 3000Pa and 600° C. for 30 minutes. After the holding time expired, the substrate was taken out, and vertical arrays of ZnO nanowires were grown on the substrate. The SEM photos of the vertical array ZnO nanowires prepared in this example are similar to those shown in Figures 1-3.

Claims (5)

1. a preparation method of vertical array ZnO nanowires, characterized in that the process steps are as follows: (1) Preparation of precursor solution Add deionized water to the reaction vessel, then add zinc salt and polyethyleneimine, and stir at room temperature and normal pressure for 0.5~3h to obtain a precursor solution; the amount of the zinc salt, deionized water and polyethyleneimine is The mass ratio of zinc, deionized water, and polyethyleneimine in the zinc salt is limited to 1:400:20~1:80:4; (2) ultrafiltration The precursor solution obtained in step (1) is subjected to ultrafiltration, and the ultrafiltration time is limited to the fact that no liquid can be separated; (3) Spin coating Add the solution intercepted in step (2) onto the substrate dropwise at a speed of 200~1000rpm, and then apply glue at a speed of 500~3000rpm for 10~60s; (4) heat treatment ①Insulate the glue-coated substrate obtained in step (3) under normal pressure, oxygen atmosphere, and 400-600°C for 30-120 minutes. After the holding time expires, cool the substrate naturally to room temperature. ②Insulate the substrate treated in step ① at normal pressure, oxygen atmosphere, and 800-1000°C for 1-10 minutes. After the holding time expires, naturally cool the substrate to room temperature. ③ Insulate the substrate treated in step ② under the conditions of 100~3000Pa, oxygen atmosphere, and 400~600°C for 5~30min. 2. The preparation method of the vertical array ZnO nanowires according to claim 1, characterized in that the zinc salt is zinc nitrate, zinc acetate or zinc chloride. 3. according to the preparation method of the described vertical array ZnO nanowire of claim 1 or 2, it is characterized in that the molecular weight cut-off of the ultrafiltration membrane that described ultrafiltration operation is used is 400～10000 g/mol. 4. The method for preparing vertical array ZnO nanowires according to claim 1 or 2, characterized in that the substrate is (0001) sapphire substrate,

sapphire base,

sapphire base, Any of sapphire substrate and (111) silicon substrate. 5. The method for preparing vertical array ZnO nanowires according to claim 3, characterized in that the substrate is (0001) sapphire substrate, sapphire base,

sapphire base, Any of sapphire substrate and (111) silicon substrate.

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