TW201602031A - ZnONanosheets layer and producing method thereof - Google Patents

Abstract

A method of prepare Zinc Oxide nano-sheet structure layer, comprising the steps of: (1) A ZnO seed layer is then deposited on the surface substrate; (2) The substrate was immersed into an aqueous solution of contained zinc ions and hydroxide ions; (3) The complex Zinc Oxide nanoparticle aggregates or replacement, and then accumulated on the Zinc Oxide seed layer surface. And gradually grow to form vertical structure Zinc Oxide nanosheet structure layer.

Description

Zinc oxide nanosheet structural layer and manufacturing method thereof

A nanostructure and process method, and more particularly to a method for producing a zinc oxide layer having a nanosheet structure.

Zn oxide (ZnO), belonging to the II-VI wide-gap semiconductor material, has a structure of wurtzite structure, lattice constant a=3.2539Ǻ, c=5.2098 Ǻ, c/a ratio Close to perfect 1.633. Zinc oxide is a direct bandgap semiconductor with an energy gap width of about 3.37 eV at room temperature and high exciton binding energy of about 60 meV with high transmittance in the visible range. . Zinc oxide materials also have photoconductive properties, piezoelectric properties, acousto-electric effects, and electro-optical effects, and are therefore widely used in photodetectors and gas detectors. And modulators, light-emitting diodes, CIGS solar cells, dye-sensitized cells (DSSC) and laser components.

In order to improve the electrical characteristics of the fabricated components, some studies have attempted to form various structures in the zinc oxide layer, such as surface roughening, formation of microstructures or growth of nano-particles, etc., which are manufactured in a microstructured zinc oxide layer. It is quite inconvenient, and it may be more improved than the simple planar zinc oxide coating, but its characteristics are still not very good, especially in the optical aspect.

In order to solve the technical problem that the existing zinc oxide layer manufacturing method is not easy and the electrical effect of the zinc oxide layer is not good, the present invention provides a method for manufacturing a zinc oxide layer having a grown nanostructure, and the oxidation of the sheet structure can be produced by a simple process. The zinc nano layer solves the problems of the prior art manufacturing difficulties and application defects.

The invention provides a method for manufacturing a zinc oxide nanosheet structural layer, the steps of which comprise:

Depositing a zinc oxide seed layer on a surface of a substrate;

The substrate is placed in an aqueous solution containing one of zinc ions and hydroxide ions;

A plurality of zinc oxide nanosheets are agglomerated or replaced and accumulated on the surface of the zinc oxide seed layer and gradually grow to form a standing sheet shape to form a zinc oxide nanosheet structural layer.

Wherein, the pH of the aqueous solution is 11-13.

Wherein, the substrate is a glass substrate, and the zinc oxide seed layer is deposited on the surface of the substrate by radio frequency magnetron sputtering.

Here, the substrate is placed in an aqueous solution containing one of zinc ions and hydroxide ions, and the glass substrate 10 is placed in the aqueous solution and kept at room temperature for reaction.

Wherein, the aqueous solution preferably contains a concentration of 0.1 M of zinc nitrate hexahydrate and a concentration of 0.4 M sodium hydroxide, and the mixture is uniformly stirred by deionized water, and the volume ratio of zinc nitrate to sodium hydroxide is 5 :75.

Wherein, the agglomeration in the aqueous solution accumulates on the surface of the zinc oxide seed layer to form a standing sheet shape, which is completed according to the following reaction steps:

The zinc ion reacts with the hydroxide ion to generate a zinc hydroxide precipitation cluster on the surface of the zinc oxide seed layer; the zinc hydroxide precipitation cluster reacts with the hydroxide ion in the aqueous solution to form a zincate ion complex; The zincate ion complex dehydrates to form a zinc oxide nanosheet structure.

The invention further provides a zinc oxide nanosheet structural layer comprising a plurality of zinc oxide nanosheets formed on a substrate and in a standing sheet shape, wherein the zinc oxide nanosheets adjacent to each other form a plurality a nanometer interval channel, each of which is mainly generated toward the c-axis direction (c-axis)

Wherein, the thickness of the zinc oxide nanosheet is within 10 nm.

Wherein, the zinc oxide nanosheet has an average length of 1.2 μm +/- 10%.

The zinc oxide nanosheet 24 has an average thickness of 5 nm +/- 10%.

As can be seen from the above description, the present invention has the following advantages:

1. The invention adopts an aqueous solution method to form a zinc oxide nanosheet structure, which can be chemically reacted in a general container to form a solid product, and the crystal product obtained by the high-temperature sintering method can not only eliminate the grinding process and avoid the possibility. Entrained impurities.

2. The zinc oxide nanosheet formed by the present invention is constructed as a two-dimensional nanostructure of a film type, that is, in a horizontal direction (X and Y axes) is not limited by the nanometer scale, but in the direction of the Z axis. The performance on the nanometer scale makes the invention widely applicable to components such as gas sensors, photo sensors or light-emitting diodes.

Referring to Figures 1, 2, 3a and 3b, a preferred embodiment of the method for producing a zinc oxide nanosheet structural layer of the present invention comprises the following steps:

Step 1. Depositing a zinc oxide (ZnO) seed layer 20 on the surface of a glass substrate 10:

Before depositing the zinc oxide seed layer 20, the glass substrate 10 preferably removes impurities and dirt on the surface by a chemical cleaning means for immersing the glass substrate 10 in an organic solvent. The surface is removed by impurities or oil stains, preferably immersed in acetone (Acetone) for 10 minutes, and then immersed in Isopropyl alcohol for 10 minutes, and the organic solvent is washed with a deionized water. After clean, dry at 100 ^o C for 30 minutes.

The zinc oxide seed layer 20 is preferably deposited on the surface of the glass substrate 10 by a method of a Ratio Frequency Magnetron Sputter. Preferably, the zinc oxide seed layer 20 is deposited to a thickness of 25 nm. In this embodiment, the zinc oxide seed layer 20 is deposited on the surface of the glass substrate 10 by sputtering, and the problem of lattice mismatch between the surface of the glass substrate 10 and the zinc oxide seed layer 20 can be solved. The seed layer 20 can be firmly deposited on the surface of the glass substrate 10, and the deposition range of the zinc oxide seed layer 20 can also be adjusted to control the size of the nano zinc oxide of the embodiment.

Step 2. Place the glass substrate 10 in an aqueous solution containing zinc ions (Zn ²⁺ ) and hydroxide ions (OH ^- ):

The aqueous solution of the present embodiment preferably contains a concentration of 0.1 M of zinc nitrate hexahydrate (Zn(NO ₃ ) ₂ ‧6H ₂ O) 75 mL and a concentration of 0.4 M sodium hydroxide (NaOH) 75 mL. in deionized water using a magnet stirrer reconcile stir the glass substrate 10 is placed in the solution and maintained at room temperature (25 ^o C) for 1 hour, the pH of the aqueous solution is preferably 11 ~ 13.

Step3. Growing zinc oxide nanosheet structural layer:

A plurality of zinc oxide nanosheets 24 are agglomerated or replaced and accumulated on the surface of the zinc oxide seed layer 20 and gradually grow to form a standing sheet form to form a zinc oxide nanosheet structural layer, as shown in FIG. The zinc oxide nanosheets 24 adjacent to each other form a plurality of nano-spaced channels which are spaces formed by adjacent continuous surfaces of the zinc oxide nanosheet structure, the nanometer The spacer channel can be reflected multiple times with an external light entering the adjacent surface of the zinc oxide nanosheet 24, so that the zinc oxide nanosheet 24 greatly enhances the photoelectric effect that may be generated. Thus, when the zinc oxide nanosheet structural layer of the embodiment is applied to a photosensor, the sensing sensitivity can be greatly improved to achieve the best sensing performance of other types of plating or other microstructures.

The principle of the reaction mechanism in which the zinc oxide nanosheet 24 is agglomerated in the aqueous solution to form a standing sheet-like pattern on the surface of the zinc oxide seed layer 20 is briefly described below:

Zn ²⁺ +2OH ^- →Zn(OH) ₂ ↓(1)

Zn(OH) ₂ +2 OH ^- →Zn(OH) ₄ ^2- (2)

Zn(OH) ₄ ^2- →ZnO+2H ₂ O+2OH ^- (3)

Formula (1), zinc ion (Zn ²⁺ ) reacts with hydroxide ion (OH ^- ) to produce zinc hydroxide (Zn(OH) ₂ ) precipitate clusters in the zinc oxide seed layer 20 surface;

Formula (2), zinc hydroxide precipitate clusters (Zn(OH) ₂ clusters) react with hydroxide ions (OH ^- ) in aqueous solution to form zincate ion complex (Zincate ion, Zn(OH) ₄ ^2- ) ;

Formula (3), zincate ion complex (Zincate ion, Zn(OH) ₄ ^2- ) dehydrates to form a zinc oxide deposit (ZnO).

In the present invention, the zinc oxide nanosheet 24 is formed by an aqueous solution method, and the pH value in the aqueous solution is changed by using sodium hydroxide (NaOH) to cause a metal ion complex reaction in the aqueous solution, because the pH value in the aqueous solution changes little. The concentration of the metal ion complex formed is low, and the zinc oxide crystallization reaction is carried out under an aqueous solution of low supersaturation.

The surface activation energy required for Homogeneous nucleation in an aqueous solution is greater than the surface activation energy to be overcome by heterogeneous nucleation on the surface of the glass substrate 10, so in an aqueous solution with low supersaturation, the glass The heterogeneous growth of the surface of the substrate 10 is easier than the homogeneous growth in the aqueous solution, and the sodium hydroxide (NaOH) adjusts the aqueous solution to an alkaline environment, causing the metal ion complex to carry a charge, and the metal ion complex is charged. Mutual exclusion is less likely to accumulate in aqueous solution. The surface of the glass substrate 10 of the present invention is previously plated with a zinc oxide seed layer 20, and the zincate ion complex in the aqueous solution can directly react with the zinc oxide crystal to grow the zinc oxide along the crystal surface. The activation energy at the time of heterogeneous growth is lowered, and the efficiency of the formation of the zinc oxide nanosheet 24 is improved.

Referring to FIG. 2, the X-ray diffraction analysis of the present invention shows that the direction of accumulation of the zinc oxide nanosheet 24 is mainly c-axis-elongated, wherein (002 The diffracted wave peak is larger than the other wave peaks such as (100), (101), (102), (110), (103), and (112), and the zinc oxide nanosheet 24 of the present invention is mainly oriented toward the c-axis direction ( C-axis) generated.

Please refer to FIG. 3a, 3b, which shows that the zinc oxide nanosheet 24 of the present invention is formed on the surface of the zinc oxide seed layer 20 in a standing sheet form, and the average thickness of the zinc oxide nanosheet 24 is about 5 nm+/ -10%, an average length of about 1.2 μm +/- 10%, staggered on the surface of the zinc oxide seed layer 20.

As can be seen from the above description, the present invention has the following advantages:

1. The invention adopts an aqueous solution method to form a zinc oxide nanosheet structure, which can be chemically reacted in a general container to form a solid product, and the crystal product obtained by the high-temperature sintering method can not only eliminate the grinding process and avoid the possibility. Entrained impurities.

2. The zinc oxide nanosheet formed by the present invention is constructed as a two-dimensional nanostructure of a film type, that is, in a horizontal direction (X and Y axes) is not limited by the nanometer scale, but in the direction of the Z axis. The performance on the nanometer scale makes the invention widely applicable to components such as gas sensors, photo sensors or light-emitting diodes.

10‧‧‧ glass substrate
20‧‧‧Zinc oxide seed layer
22‧‧‧ Reunion
24‧‧‧Zinc oxide nanosheet construction

1 is a schematic view showing the formation process of a zinc oxide nanosheet structural layer formed on a zinc oxide seed layer according to a first preferred embodiment of the present invention. 2 is a view of an X-ray diffraction pattern of a zinc oxide nanosheet structure according to a preferred embodiment of the present invention. 3a, 3b are electron micrographs of a structural layer of a zinc oxide nanosheet according to a preferred embodiment of the present invention.

10‧‧‧ glass substrate

20‧‧‧Zinc oxide seed layer

22‧‧‧ Reunion

24‧‧‧Zinc oxide nanosheet construction

Claims (10)

A zinc oxide nanosheet structural layer comprising a plurality of zinc oxide nanosheets formed on a substrate and in a standing sheet shape, wherein the zinc oxide nanosheets adjacent to each other form a plurality of nanometer intervals Channels, each of which is formed primarily toward the c-axis. The zinc oxide nanosheet structural layer according to claim 1, wherein the zinc oxide nanosheet has a thickness of 10 nm or less. The zinc oxide nanosheet structural layer according to claim 1 or 2, wherein the zinc oxide nanosheet has an average length of 1.2 μm +/- 10%. The zinc oxide nanosheet structure layer has an average thickness of 5 nm +/- 10% as claimed in claim 3 of the zinc oxide nanosheet construction layer. A method for manufacturing a zinc oxide nanosheet structural layer, comprising the steps of: depositing a zinc oxide seed layer on a surface of a substrate; placing the substrate in an aqueous solution containing one of zinc ions and hydroxide ions; The zinc oxide nanosheets are agglomerated or replaced and accumulated on the surface of the zinc oxide seed layer and gradually grow to form a standing sheet shape to form a zinc oxide nanosheet structural layer. The method for producing a zinc oxide nanosheet structural layer according to claim 5, wherein the aqueous solution has a pH of 11 to 13. The method for manufacturing a zinc oxide nanosheet structural layer according to claim 5 or 6, wherein the substrate is a glass substrate, and the zinc oxide seed layer is deposited on the surface of the substrate by radio frequency magnetron sputtering. The method for producing a zinc oxide nanosheet structural layer according to claim 7, wherein the substrate is placed in an aqueous solution containing one of zinc ions and hydroxide ions, and the glass substrate 10 is placed in the method. The reaction is carried out in an aqueous solution and kept at room temperature. The method for producing a zinc oxide nanosheet structural layer according to claim 8, wherein the aqueous solution preferably contains a concentration of 0.1 M of a hexahydrate nitric acid and a concentration of 0.4 M sodium hydroxide to be deionized water. After the mixer was stirred evenly, the volume ratio of nitric acid to sodium hydroxide was 5:75. The method for producing a zinc oxide nanosheet structural layer according to claim 7, wherein the agglomeration of the aqueous solution accumulates on the surface of the zinc oxide seed layer to form a standing sheet shape, which is completed according to the following reaction steps: zinc The ions react with the hydroxide ions to generate zinc hydroxide precipitation clusters on the surface of the zinc oxide seed layer; the zinc hydroxide precipitation cluster reacts with the hydroxide ions in the aqueous solution to form a zincate ion complex; and zinc The acid ion complex is dehydrated to form a zinc oxide nanosheet structure.