CN104505343B - A kind of method of making ZnO nanometer fence - Google Patents

Abstract

The invention discloses a method for preparing a ZnO nano-fence, which is characterized in that it comprises the following steps: (1) GaN substrate photolithography; (2) the substrate is coated with a gold catalyst reaction solution; (3) the substrate is heated, the solution Shrinkage; (4) Gold was reduced from the solution and distributed in a closed ring; (5) ZnO nanowire fences were induced by catalysts by CVD. The invention utilizes the difference in hydrophilicity and hydrophobicity of the substrate surface after photolithography to control the distribution of nano-gold particles, thereby inducing the growth of nanowire fences, which is different from the traditional control method and has obvious innovative significance and expects a wider application range.

Description

A kind of method for preparing ZnO nano fence

technical field

The invention relates to a method for preparing ZnO nano semiconductor material, in particular to a method for preparing ZnO nano barriers.

Background technique

As a semiconductor material with excellent piezoelectric and photoelectric properties, zinc oxide (ZnO) has excellent electrical, optical and chemical stability. Compared with semiconductor materials such as Si and GaN, it has a large band gap ( Eg=3.37eV) and high exciton binding energy (60meV), the one-dimensional ZnO nanostructure has a unique shape and excellent performance, and has been made into a variety of one-dimensional nanostructures, such as nanorods, nanowires, nanotubes , nanobelts, nanocombs, nanosprings, nanobows and nanothrusters are widely used in new nanodevices and systems such as nanogenerators, nanolasers, LEDs, sensors, and solar cells. Heterojunction semiconductor devices composed of third-generation semiconductor materials ZnO and GaN have shown great application value, and high-quality p, i, and n-type GaN epitaxial layers have been mass-produced. Due to the different preparation methods of ZnO nanowires, the structure has diversity, and the morphology of ZnO nanowires has a great influence on the performance of ZnO nanodevices. Therefore, the control of the growth and arrangement of ZnO one-dimensional nanowires is of great importance Very important.

In the prior art, the preparation of ZnO nanowire fences usually first adopts photolithography to carve corresponding patterns on the substrate, and then coats a gold catalyst film. After removing the photoresist, a fence-shaped catalyst pattern is left on the substrate, and then ZnO nanowires are grown by high-temperature CVD method, thereby forming ZnO nanowire fences. The disadvantage is that the photoresist is covered by a gold film, which is difficult to remove, and the size of the fence is difficult to make smaller due to the limitation of photolithography technology. Wang, X.D et al. reported a method for preparing nanowire fences using catalysts. In this method, a single-layer close-packed polystyrene microsphere (PS) was used as a mask, and gold was evaporated onto the substrate to form a honeycomb-shaped gold catalyst, which was then processed by high-temperature CVD. ZnO nanowires grown by this method can produce hexagonal nanowire fences. The size of the hexagonal pattern in this method is controlled by the size of the PS ball, and the side length is typically about 0.5 μm (Large-scale hexagonal-patterned growth of aligned ZnOnanorods for nano-optoelectronics and nanosensor arrays. Nano Letters, 2004.4 (3): p.423-426). This document uses single-layer close-packed polystyrene microspheres (PS) instead of photoresist as a mask, and the technology is relatively complicated.

Contents of the invention

In order to overcome the problems of the technologies described above, the object of the present invention is to provide a method for preparing ZnO nano barriers, comprising the steps of: (1) GaN substrate photolithography; (2) substrate coating gold catalyst reaction solution; (3) heating substrate, the solution shrinks; (4) the gold is reduced from the solution and is distributed in a closed ring; (5) the ZnO nanowire fence is induced and grown by the catalyst by the CVD method.

The further method of the present invention includes: first photoetching a certain pattern on the GaN substrate, then coating a mixed aqueous solution of HAuCl ₄ and a reducing agent, heating the substrate, and washing away the photoresist after the solvent is completely volatilized; The substrate is placed in a vacuum tube furnace, and a high-temperature chemical vapor deposition method (CVD) is used. A boat containing chemical reactants is placed in the middle of the high-temperature tube vacuum furnace. The chemical reactants include zinc oxide powder and graphite powder. Place the substrate in place, then use a mechanical pump to evacuate the vacuum tube furnace, heat the vacuum tube to 800-1200°C, then feed the carrier gas, control the pressure to 30-400 mbar, and set the growth time according to the required nanowire length , and then let the vacuum tube furnace cool down naturally, and the zinc oxide nanowire fence can be prepared on the GaN substrate.

In the above technical scheme, the reducing agent is selected from one or more of reducing organic small molecules such as EG (ethylene glycol), ethanol, acetaldehyde or citric acid. Different reducing agents have different valence changes in the reaction, so the ratio is not fixed and must be determined according to the chemical reaction equation. When the ratio of HAuCl ₄ to the reducing agent is less than the stoichiometric ratio, the reducing agent is kept in excess.

In any of the above technical solutions, the substrate is heated at a temperature of 80-100°C; the substrate is placed in the range of 0-10cm downstream of the airflow of the boat containing the chemical reactants.

In any of the above technical solutions, the mass ratio of zinc oxide powder to graphite powder is 1:1-9:4; S, Co, Ni, P and other doping elements can also be introduced.

In any of the above technical solutions, the carrier gas includes working gas and oxygen; the working gas is selected from nitrogen, argon or helium. The partial pressure of oxygen in the carrier gas is 1-2%.

The usual photolithography steps can be used to lithographically produce a certain pattern on the GaN substrate: 1, substrate cleaning; 2, spin-coating photoresist; 4, pre-baking; 5, exposure (the mask plate provides photolithographic patterns); 6 , development; 7, post-baking.

The invention utilizes the difference in hydrophilicity and hydrophobicity of the substrate surface after photolithography to control the distribution of nano-gold particles, thereby inducing the growth of nanowire fences, which is different from traditional control methods and has obvious innovative significance and expects a wider application range. For the GaN substrate after photolithography, due to the hydrophobicity of the GaN surface, the contact between the photoresist and the substrate is the place where the gold plating solution shrinks and stays, and the final gold catalyst particles will also exist in this place. Therefore, when a closed hole is photolithographically formed, the gold catalyst will be closed and distributed along the edge of the hole, thereby inducing the growth of a nanowire fence. The invention can control the distribution of catalyst by using the difference of hydrophilicity and hydrophobicity on the surface of the substrate, so as to further control the growth of nanometer material, and can also be applied to the preparation of other nanowire fences. For example: gold catalysts can be prepared in the same way to control the growth position of InP nanowires. It can also be used to prepare Fe catalysts to control the growth position of carbon nanotubes.

Description of drawings

Accompanying drawing 1 is the schematic diagram of GaN substrate photolithography step;

Accompanying drawing 2 is the schematic diagram of substrate coating gold catalyst reaction solution step;

Accompanying drawing 3 is a schematic diagram of heating the substrate and shrinking the solution to the edge of the step;

Accompanying drawing 4 is that gold is reduced from the solution, and is distributed into a closed ring schematic diagram along the steps;

Accompanying drawing 5 is the schematic diagram that uses CVD method to induce the growth of nano barriers by catalyst;

Accompanying drawing 6 is the scanning electron micrograph of ZnO nanowire fence.

detailed description

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.

Example 1

A certain pattern is photolithographically etched on the GaN substrate. The photolithography steps: firstly coat the photoresist (Su82000) film on the cleaned GaN substrate by spin coating method, then bake at 120°C for 20min, UV exposure (3mw, 30s) is used under the cover of the hole mask, the exposed part is washed away in the developer, and the substrate after photolithography is obtained by baking at 120°C for more than 20min. Then coat a mixed solution of 5mM HAuCl ₄ and 0.2v/v% EG, heat the substrate to 90°C, and wash off the photoresist with acetone after the solvent is completely volatilized; put the treated substrate into a vacuum tube furnace, and use High-temperature chemical vapor deposition method (CVD), place a boat filled with chemical reactants (zinc oxide powder and graphite powder) in the middle of a high-temperature tube-type vacuum furnace, place a substrate within 5cm of the downstream position of the airflow, and then use a mechanical pump to vacuum tube-type The furnace is evacuated, the vacuum tube is heated to 960 degrees, and then 100sccm nitrogen and 1.5sccm oxygen are introduced, the pressure is controlled to 300 mbar, and the growth is 20 minutes, then the vacuum tube furnace is allowed to cool down naturally, and the GaN substrate can be prepared. Zinc oxide nanowire fence (see accompanying drawing 6).

Example 2

A certain pattern is photolithographically etched on the GaN substrate. The photolithography steps: firstly coat the photoresist (Su82000) film on the cleaned GaN substrate by spin coating method, then bake at 120°C for 20min, UV exposure (3mw, 30s) is used under the cover of the hole mask, the exposed part is washed away in the developer, and the substrate after photolithography is obtained by baking at 120°C for more than 20min. Then coat a mixed solution of 5mM HAuCl ₄ and 0.2v/v% ethanol, heat the substrate to 100°C, and wash off the photoresist with acetone after the solvent is completely volatilized; put the treated substrate into a vacuum tube furnace, and use High-temperature chemical vapor deposition method (CVD), place a boat filled with chemical reactants (zinc oxide powder and graphite powder) in the middle of the high-temperature tube-type vacuum furnace, place the substrate within 8cm of the downstream position of the airflow, and then use a mechanical pump to vacuum the tube-type The furnace is evacuated, the vacuum tube is heated to 1200 degrees, and then 100sccm argon and 1.5sccm oxygen are introduced, the pressure is controlled to 100 mbar, and the growth is 2 hours, and then the vacuum tube furnace is naturally cooled, and it can be prepared on the GaN substrate. out ZnO nanowire fence.

Example 3

A certain pattern is photolithographically etched on the GaN substrate. The photolithography steps: firstly coat the photoresist (Su82000) film on the cleaned GaN substrate by spin coating method, then bake at 120°C for 20min, UV exposure (3mw, 30s) is used under the cover of the hole mask, the exposed part is washed away in the developer, and the substrate after photolithography is obtained by baking at 120°C for more than 20min. Then coat a mixed solution of 5mM HAuCl ₄ and 0.2v/v% acetaldehyde, heat the substrate to 100°C, and wash off the photoresist with acetone after the solvent is completely volatilized; put the treated substrate into a vacuum tube furnace, and use Using high-temperature chemical vapor deposition (CVD), place a boat filled with chemical reactants (zinc oxide powder and graphite powder) in the middle of a high-temperature tube-type vacuum furnace, place the substrate within 8cm of the downstream position of the airflow, and then use a mechanical pump to pump the vacuum tube Vacuum the vacuum tube, heat the vacuum tube to 1200 degrees, then feed 100sccm argon and 1.5sccm oxygen, control the pressure to 100 mbar, grow for 2 hours, then let the vacuum tube furnace cool down naturally, and then put it on the GaN substrate. ZnO nanowire fences were prepared.

Example 4

A certain pattern is photolithographically etched on the GaN substrate. The photolithography steps: firstly coat the photoresist (Su82000) film on the cleaned GaN substrate by spin coating method, then bake at 120°C for 20min, UV exposure (3mw, 30s) is used under the cover of the hole mask, the exposed part is washed away in the developer, and the substrate after photolithography is obtained by baking at 120°C for more than 20min. Then coat a mixed solution of 5mM HAuCl ₄ and 0.2v/v% EG, heat the substrate to 100°C, and wash off the photoresist with acetone after the solvent is completely volatilized; put the treated substrate into a vacuum tube furnace, and use High-temperature chemical vapor deposition method (CVD), a boat filled with chemical reactants (zinc oxide powder, graphite powder and Al ₂ O ₃ powder mixed) is placed in the middle of a high-temperature tube vacuum furnace, and the substrate is placed within 8cm downstream of the air flow. Then use a mechanical pump to evacuate the vacuum tube furnace, heat the vacuum tube to 1100 degrees, then feed 100 sccm argon and 1.5 sccm oxygen, control the pressure to 100 mbar, grow for 2 hours, then let the vacuum tube furnace cool down naturally. Al-doped ZnO nanowire fences can be fabricated on GaN substrates.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention shall still be covered by the claims of the present invention.

Claims (9)

1. A method for preparing ZnO nano barriers, is characterized in that, comprises the steps: (1) GaN substrate photolithography; (2) substrate coating gold catalyst reaction solution; (3) heating substrate, solution shrinks; (4) The gold is reduced from the solution, and it is distributed in a closed ring; (5) The ZnO nanowire fence is induced by the catalyst by CVD; first, a certain pattern is photoetched on the GaN substrate, and then coated with HAuCl ₄ and reduced Mix the aqueous solution with the solvent, heat the substrate, and wash off the photoresist after the solvent is completely volatilized; put the treated substrate into a vacuum tube furnace, and use high-temperature chemical vapor deposition (CVD) to place it in the middle of the high-temperature tube vacuum furnace. A boat filled with chemical reactants, which include zinc oxide powder and graphite powder, places the substrate at the downstream position of the air flow, then vacuumizes the vacuum tube furnace with a mechanical pump, heats the vacuum tube to 800-1200°C, and then passes it into the Carrier gas, control the pressure to 30-400 mbar, set the growth time according to the required nanowire length, and then let the vacuum tube furnace cool down naturally, and the zinc oxide nanowire fence can be prepared on the GaN substrate. 2. The method for preparing ZnO nano-fences as claimed in claim 1, wherein the reducing agent is selected from one or more of EG (ethylene glycol), ethanol, acetaldehyde or citric acid. 3. The method for preparing ZnO nano fences as claimed in claim ₁ , characterized in that the ratio of the HAuCl to the reducing agent is less than the stoichiometric ratio, that is, the excess state of the reducing agent is maintained. 4. The method for preparing ZnO nano-fences according to claim 1, characterized in that the temperature of the substrate is heated to 80-100°C. 5. The method for preparing ZnO nano-barriers according to claim 1, wherein the substrate is placed in the range of 0-10 cm downstream of the airflow of the boat containing the chemical reactants. 6. The method for preparing ZnO nano-fences according to claim 1, characterized in that the mass ratio of the zinc oxide powder to the graphite powder is 1:1-9:4. 7. The method for preparing ZnO nano-fences according to claim 1, wherein the chemical reactants include Ga, Al, As, Sb, Cu, S, Co, Na, Ni or P doping elements. 8. The method for preparing a ZnO nano-barrier as claimed in claim 1, wherein the carrier gas comprises working gas and oxygen. 9. The method for preparing ZnO nano-fences according to claim 8, wherein the working gas is selected from nitrogen, argon or helium, and the partial pressure of oxygen in the carrier gas is 1-2%.