CN1669920A - Preparation method of one-dimensional silicon nanostructure in anodized alumina template - Google Patents

Abstract

The invention discloses a preparation method of a one-dimensional silicon nanostructure in an anodic alumina template. Firstly, a one-dimensional silicon nano structure comprising a silicon nano wire and a silicon nano tube is grown at a low temperature by utilizing a plasma chemical deposition method and combining the space limitation effect of porous alumina. Firstly, preparing a porous alumina template with a honeycomb pore structure by an anodic oxidation method, wherein the pores are orderly arranged, have consistent pore diameter and are vertical to the template surface. Then the template is placed into a plasma enhanced chemical deposition reaction chamber, high-hydrogen diluted silane is used as a growth gas source, and the gas flow is controlled at the temperature of 300 ℃ to grow the silicon nanowire or the silicon nanotube. The invention has the advantages of low synthesis temperature, short time, cheap raw materials and simple operation, and can obtain the silicon nanowire and the silicon nanotube without introducing a catalyst, thereby avoiding pollution. The diameter of the obtained silicon nanowire is consistent with that of the silicon nanotube under the space limitation action of the template, the silicon nanowire is adjustable between 20 nm and 100nm, and the length of the silicon nanowire is increased along with the growth time.

Description

Preparation method of one-dimensional silicon nanostructure in anodized alumina template

technical field

The invention relates to a method for preparing a one-dimensional silicon nanostructure in an anodized aluminum template. Specifically, it is a method for growing silicon nanowires and silicon nanotubes at low temperature in a plasma-enhanced chemical vapor deposition reaction chamber by using the regular hole structure of an anodized aluminum template.

Background technique

For a long time, silicon, as the most important semiconductor material in the field of microelectronics, has always been the substrate of electronic devices and large-scale integrated circuits, and its process technology and integrated circuit technology have reached a high level of development. However, the information carrier of microelectronics technology is electrons, and the transmission speed of electrons in crystals is limited, which seriously limits the speed and ability of information processing. If the light with the fastest transmission speed can also be used to represent signals and participate in signal processing with electrons, this limitation will be completely broken through. This is the optoelectronic integration that integrates optical devices and electronic devices. However, silicon is an indirect bandgap material. The recombination process of carriers requires the participation of phonons, the luminous efficiency is very low, and the light emission in the near-infrared region generated by the narrow energy bandgap, the application of silicon in optoelectronic devices is very limited. At present, light-emitting devices mainly use III-V compound semiconductor materials represented by GaAs. Their luminous efficiency is 100,000 times higher than that of silicon, but their physical and chemical characteristics are quite different from those of silicon, and they are not compatible with silicon integration processes. It has failed to develop a planar process and integration technology that can compete with silicon, and has never been able to replace silicon in terms of microelectronic integration and optoelectronic integration. People have turned their hopes for the basic material of optoelectronic integration to silicon. If luminescent materials can be manufactured on silicon, a set of silicon optoelectronic integration technology can be developed by using the existing silicon integration technology, thus completely changing the face of information technology. The crux of the problem lies in the exploration of silicon-based light-emitting materials.

In 1990, Canham reported the photoluminescence phenomenon of porous silicon at room temperature, and gave a mechanism explanation of the quantum wire confinement effect. It broke the confinement of silicon as an indirect bandgap material that is difficult to achieve high-efficiency luminescence, and provided silicon materials in optoelectronics. Applications in the field of science have opened up new horizons. However, porous silicon has poor luminescence stability, is sensitive to the environment, and the luminescence intensity decays with time and is accompanied by a blue shift of the luminescence peak, which limits its practical application. Inspired by luminescent porous silicon, silicon-based low-dimensional luminescent materials have also received attention. Utilizing the quantum size confinement effect on its energy band structure, the probability of luminescent recombination is increased by widening the energy gap, or changing the energy gap from indirect to direct. The discovery of excellent properties of carbon nanotubes has aroused people's interest in one-dimensional silicon nanomaterials. However, most of the current research focuses on the preparation and research of silicon nanowires. The deposition temperature is high (generally 800-1100°C), and metal catalysts need to be introduced to assist the growth. Performance testing and application of silicon nanowires.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a one-dimensional silicon nanostructure in an anodic oxide aluminum template. In a plasma-enhanced vapor deposition reaction system, a method for preparing solid silicon nanowires and hollow silicon nanotubes through gas flow control under low temperature conditions.

The steps of the method are as follows:

1) A porous alumina template with a honeycomb pore structure is prepared by anodic oxidation, and the holes are regularly arranged vertically to the template surface with the same pore diameter;

2) Put the porous alumina template into the plasma-enhanced chemical deposition reaction chamber with a radio frequency power of 60-100W, a reaction temperature of 250-400°C, a reaction pressure of 90-130Pa, and dilute SiH ₄ and H ₂ with 10% hydrogen for growth Gas source, the gas flow rate is 10-40 sccm, silicon nanowires are generated when the gas flow rate is 10-20 sccm, and silicon nanotubes are generated when the gas flow rate is 30-40 sccm.

The steps of the method for preparing a porous alumina template with a honeycomb structure are as follows:

1) Degrease the 99.999% high-purity aluminum sheet and anneal it at 450-550°C for 4-6 hours, then polish it in a mixed solution of sulfuric acid and phosphoric acid, and put the polished aluminum sheet in 0.3-0.5mol/L oxalic acid solution Carry out the first step of anodizing in the middle, react at 0-10°C for 2-4 hours, and the anodizing voltage is 30-50V;

2) Soak in a mixed solution of phosphoric acid and cadmium acid for 1 to 2 hours;

3) adopting the same parameters as step 1) to carry out two-step anodic oxidation to form the pore structure of porous alumina;

4) Use a saturated CuSO ₄ solution to remove unoxidized aluminum, and finally expand holes in 4-6% phosphoric acid and corrode the barrier layer at the bottom of the alumina to form a through alumina template.

The invention has low synthesis temperature, short time, cheap raw materials and simple operation, and can obtain silicon nanowires and silicon nanotubes without introducing a catalyst, thereby avoiding pollution. The diameter of the obtained silicon nanowire and silicon nanotube is consistent through the space limitation of the template, which is adjustable between 20 and 100 nm, and the length increases with the extension of the growth time. Therefore, it is an economical and convenient preparation method for obtaining high-quality silicon nanowires and silicon nanotubes.

Description of drawings

Fig. 1 is the typical transmission electron micrograph of silicon nanowire of the present invention;

Fig. 2 is a typical transmission electron micrograph of the silicon nanotube of the present invention.

Detailed ways

Example 1

Degrease the 99.999% high-purity aluminum sheet and anneal it at 500°C for 5 hours, and then polish it in a mixed solution of sulfuric acid and phosphoric acid. After polishing, the aluminum sheet is used as the anode, and the graphite is used as the cathode. In the first step of anodic oxidation, after anodic oxidation at 30V for 4 hours, it was etched in a mixed solution of 1.8wt% H ₂ CrO ₄ +6wt% H ₃ PO ₄ for 2 hours to remove the oxide layer, and then the second step was carried out with the same parameters as the first step. Step anodic oxidation to form the pore structure of porous alumina, and finally use saturated CuSO ₄ solution to remove unoxidized aluminum, and expand the pores in 5% phosphoric acid for 30min to obtain a porous alumina template with a pore size of 30nm.

Put the 30nm aperture porous alumina template into the plasma-enhanced chemical vapor deposition reaction chamber. After the temperature rises to 250°C, 20 sccm of SiH ₄ /H ₂ mixed gas (the volume ratio of SiH ₄ and H ₂ is 1:40) , adjusting the pressure of the reaction chamber to 90Pa, the radio frequency power to 60W, and growing for 3h after ignition to obtain silicon nanotubes with a diameter of 30nm and a length of about 4μm.

Example 2

Degrease the 99.999% high-purity aluminum sheet and anneal it at 500°C for 5 hours, and then polish it in a mixed solution of sulfuric acid and phosphoric acid. After polishing, the aluminum sheet is used as the anode, and the graphite is used as the cathode. The first step of anodizing, after anodizing at 50V for 4 hours, corroded in a mixed solution of phosphoric acid and cadmium acid for 2 hours to remove the oxide layer, and then using the same parameters as the first step for two-step anodizing to form a porous aluminum oxide pore structure , and finally use a saturated CuSO ₄ solution to remove unoxidized aluminum, and expand the pores in 5% phosphoric acid for 60 minutes to obtain a porous alumina template with a pore size of 100 nm.

Put the 100m aperture porous alumina template into the plasma-enhanced chemical vapor deposition reaction chamber, raise the temperature to 400°C, and feed 80 sccm of SiH ₄ /H ₂ mixed gas (the volume ratio of SiH ₄ and H ₂ is 1:20) , adjusting the pressure of the reaction chamber to 130Pa, the radio frequency power to 110W, and growing for 3h after initiation, to obtain silicon nanowires with a diameter of 100nm and a length of about 10μm.

Example 3

Degrease the 99.999% high-purity aluminum sheet and anneal it at 500°C for 5 hours, and then polish it in a mixed solution of sulfuric acid and phosphoric acid. After polishing, the aluminum sheet is used as the anode, and the graphite is used as the cathode. In the first step of anodic oxidation, after anodic oxidation at 40V for 4 hours, it was etched in a mixed solution of 1.8wt% H ₂ CrO ₄ +6wt% H ₃ PO ₄ for 2 hours to remove the oxide layer, and then the second step was carried out with the same parameters as the first step. Step anodic oxidation to form the pore structure of porous alumina, and finally use saturated CuSO ₄ solution to remove unoxidized aluminum, and expand the pores in 5% phosphoric acid for 45min to obtain a porous alumina template with a pore size of 60nm.

Put the 60nm aperture porous alumina template into the plasma-enhanced chemical vapor deposition reaction chamber, wait for the temperature to rise to 300°C, and feed 40 sccm of SiH ₄ /H ₂ mixed gas (the volume ratio of SiH ₄ and H ₂ is 1:20) , adjusting the pressure of the reaction chamber to 110Pa, the radio frequency power to 70W, and growing for 3h after initiation, to obtain silicon nanotubes with a diameter of 60nm and a length of about 6μm.

Example 4

Degrease the 99.999% high-purity aluminum sheet and anneal it at 500°C for 5 hours, and then polish it in a mixed solution of sulfuric acid and phosphoric acid. After polishing, the aluminum sheet is used as the anode, and the graphite is used as the cathode. In the first step of anodic oxidation, after anodic oxidation at 40V for 4 hours, it was etched in a mixed solution of 1.8wt% H ₂ CrO ₄ +6wt% H ₃ PO ₄ for 2 hours to remove the oxide layer, and then the second step was carried out with the same parameters as the first step. Step anodic oxidation to form the pore structure of porous alumina, and finally use saturated CuSO ₄ solution to remove unoxidized aluminum, and expand the pores in 5% phosphoric acid for 45min to obtain a porous alumina template with a pore size of 60nm.

Put a 60nm aperture porous alumina template into the plasma-enhanced chemical vapor deposition reaction chamber, raise the temperature to 300°C, and feed 60 sccm of SiH ₄ /H ₂ mixed gas (the volume ratio of SiH ₄ and H ₂ is 1:20) , adjusting the pressure of the reaction chamber to 110Pa, the radio frequency power to 70W, and growing for 3h after initiation, to obtain silicon nanowires with a diameter of 60nm and a length of about 8μm.

Claims (3)

1. the preparation method of one-dimensional silicon nanostructure in the anodic oxidation aluminium formwork is characterized in that the step of method is as follows:

1) porous alumina formwork that adopts anodised method preparation to have the honeycomb hole structure, hole vertical formwork face is regularly arranged, the aperture unanimity;

2) porous alumina formwork being inserted radio frequency power is 60～100W plasma enhanced chemical cvd reactive chamber, and temperature of reaction is 250～400 ℃, and reaction pressure is 90～130Pa, with diluted in hydrogen SiH ₄Be the growth source of the gas, gas flow is 20～80sccm, generates silicon nanowires when gas flow is 20～40sccm, generates nano-tube when gas flow is 60～80sccm.

2. the preparation method of one-dimensional silicon nanostructure is characterized in that in a kind of anodic oxidation aluminium formwork according to claim 1, and described porous alumina formwork anodic oxidation preparation method's with honeycomb hole structure step is as follows:

1) will anneal 4～6 hours down at 450～550 ℃ after high-purity aluminium flake grease removal of 99.999%, in the mixing solutions of sulfuric acid and phosphoric acid, polish, polishing back aluminium flake carries out the first step anodic oxidation in the oxalic acid solution of 0.3～0.5mol/L, reacted 2～4 hours under 0～10 ℃ of condition, anodic oxidation voltage is 30～50V;

2) in the mixing solutions of phosphoric acid and cadmium acid, soaked 1～2 hour;

3) adopt the parameter identical to carry out the pore space structure that two-step anodic oxidization forms porous alumina with step 1);

4) use saturated CuSO ₄The aluminium that solution removal is not oxidized, the blocking layer of carrying out reaming and corrosion oxidation aluminium bottom at last in 4～6% phosphoric acid forms the alumina formwork that connects.

3. the preparation method of one-dimensional silicon nanostructure is characterized in that in a kind of anodic oxidation aluminium formwork according to claim 1, described step 2) in SiH ₄With H ₂Volume ratio be 1: 20～40.

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