TWI801776B - Producing method of pd-adsorbed zno nanostructures - Google Patents

Abstract

The present invention reveals a producing method of Pd-adsorbed ZnO nanostructures comprising: preparing an ITO substrate which comprising a plurality of Zinc oxide (ZnO) nanostructures; using a photochemical reaction method to adsorb a number of palladium (Pd) nanoparticles on the surface of ZnO nanostructures. Compare to the traditional away, such as E-beam Evaporator system or Thermal Evaporation Deposition system, the present invention by using a photochemical reaction method not only achieves the effects with simplifying the producing steps, down costing the price, but also improves the development of the field emission.

Description

Process method of zinc oxide nanocolumn adsorbing palladium

A zinc oxide nanocolumn for field emitters, especially a zinc oxide nanocolumn that adsorbs palladium and its photochemical method

The application of field emission has an inseparable relationship with modern life, including flat panel displays used in people's lives and electron beam microscopes used in medical and research fields, etc., making the application of field emission in displays and electronic devices in recent years. Extensive research. Most of the current field emitters are made by growing a plurality of nanostructures (such as nanopillars or nanotubes) on an indium tin oxide substrate. However, the advantages and disadvantages of this field emitter can be attributed to many Factors include the nanostructure, nanomaterials, electrical conductivity, work function, etc. of the field emitter. Therefore, how to improve the quality and performance of the field emitter is the most important goal in the field emission field.

In order to improve the quality and performance of the field emitter, metal oxide semiconductor (MOS) is often used as the target of development, among which ZnO has a wide energy gap (3.37eV) at room temperature. Good isoelectricity; 2. High electron binding energy (60meV) makes it have excellent luminous rate and nonlinear optical coefficient characteristics; 3. Its own chemical stability characteristics are not toxic and the material is cheap, making zinc oxide a popular choice in the field emission field Very popular nano research materials.

In addition, in the research field of metal oxide semiconductors and field emitters, a metal oxide semiconductor is doped with a noble metal nanoparticle (such as platinum, palladium, gold and silver, etc.) for oxide semiconductor modification, This increases the performance of the field emitter. However, most of the existing technologies need to use The electron beam evaporation system or the thermal evaporation system can sputter the noble metal nanoparticles on the surface of the metal oxide semiconductor, which is not only expensive and complicated, but also unfavorable for the development of the field emission field.

In order to solve the technical field of improving the quality and performance of the field emitter in the current field emission field, it can also reduce the manufacturing cost and reduce the process steps. The manufacturing method of zinc oxide nanopillars comprises the following steps: preparing an indium tin oxide substrate on which a plurality of oxide nanopillars grow; using a photochemical reaction to make the plurality of zinc oxide nanopillars There are complex palladium nanoparticles adsorbed on the surface of the rice pillar.

Wherein, the step of the photochemical reaction includes: dropping a palladium chloride aqueous solution onto a plurality of the zinc oxide nanocolumns; and exposing the plurality of the zinc oxide nanocolumns dripped with the palladium chloride aqueous solution to an ultraviolet ray light source.

Wherein, a zinc oxide film is formed on the indium tin oxide substrate by a sputtering method, and the sputtering method includes a radio frequency magnetron sputtering system.

Wherein, the thickness of the zinc oxide film is between 25 nanometers (nm) and 100 nanometers (nm).

Wherein, using a hydrothermal method to grow a plurality of the zinc oxide nanocolumns, the step of the hydrothermal method includes: immersing the indium tin oxide substrate in a molar concentration ratio of 1:1 mixed with zinc nitrate hexahydrate and in the cyclohexamethylenetetramine solution; and reacted at 90° C. for 6 hours.

Wherein, the volume of the palladium chloride aqueous solution is 500 microliters, and the concentration of the palladium chloride aqueous solution is 1 millimole per liter.

Wherein, the wavelength of the ultraviolet light source is 365 nm, the intensity of the ultraviolet light source is 0.496 milliwatts, and the duration of exposure of the plurality of zinc oxide nanopillars to the ultraviolet light source is 480 seconds.

Further, the indium tin oxide substrate is plated with a silver layer as a contact electrode.

Compared with the zinc oxide nanopillars, when the same electric field is given to the zinc oxide nanopillars adsorbing palladium, the field emission performance of the zinc oxide nanopillars adsorbing palladium is significantly better than that of the zinc oxide nanopillars .

Compared with the traditional electron beam evaporation system or thermal evaporation system to sputter the palladium nanoparticles on the surface of the zinc oxide nanopillars, the present invention utilizes the photochemical reaction to make the palladium ions from the solution The adsorption on the surface of the zinc oxide nano-column 13 is not only simple in steps and cheap in price, but also conducive to the development of the field emission field.

10: Zinc Oxide Nanocolumns Adsorbing Palladium

11: Indium tin oxide substrate

12: Zinc oxide film

13: ZnO nanopillars

14: Palladium nanoparticles

15: silver layer

20: palladium chloride aqueous solution

30: UV light source

e ^- : electron

Fig. 1 is a step diagram of a preferred embodiment of the present invention

Fig. 2 is the electric display diagram of preferred embodiment of the present invention

Fig. 3 is the X-ray diffractometer analysis figure of preferred embodiment of the present invention

Fig. 4 is the analysis diagram of photoluminescence spectrometer of preferred embodiment of the present invention

Fig. 5 is a field emission result figure of a preferred embodiment of the present invention

Fig. 6 is a field emission slope diagram of a preferred embodiment of the present invention

Fig. 7 is a schematic diagram of the field emission energy band measured by an externally applied electric field in a preferred embodiment of the present invention

As shown in Fig. 1, it is a kind of manufacturing process method of zinc oxide nanocolumn 10 that adsorbs palladium that the preferred embodiment of the present invention provides, and its steps include: 1. prepare and clean an indium tin oxide substrate 11, this indium tin oxide The bottom of the object substrate 11 is a glass plate, and the upper layer of the glass plate is coated with an indium tin oxide film. The indium tin oxide substrate 11 is cleaned by using acetone, methanol (isopropyl alcohol) and deionized water with an ultrasonic oscillator. 2. Using the RF magnetron sputtering system (RF magnetron sputtering system), in a vacuum environment (4*10 ^-6 Torr), sputter zinc oxide nanoparticles with a diameter of 3-inch on the indium tin oxide A zinc oxide film 12 is formed on the upper layer of the object substrate 11, and the thickness of the zinc oxide film 12 is approximately between 25 nanometers (nm) and 100 nanometers (nm). 3. Use a hydrothermal method (hydrothermal method) to grow into a plurality of zinc oxide nanopillars 13. 4. Use a photochemical reaction to make a plurality of zinc oxide nanopillars 13 surface adsorbed with a plurality of palladium nanoparticles 14 5. In a vacuum environment (6*10 ^-6 Torr), the indium tin oxide substrate 11 is plated with a silver layer 15 as a contact electrode, and the thickness of the silver layer 15 is about 100 nanometers (nm) .

The steps and conditions of the hot water method include: 1. The indium tin oxide substrate 11 coated with the zinc oxide layer 12 is immersed in zinc nitrate hexahydrate ( Zn(NO3)2_6H2O) and hexamethylenetetramine (C6H12N4, HMTA) solution. 2. Reacting for 6 hours in an environment of 90° C. to grow a plurality of the zinc oxide nanopillars 13 .

Wherein the steps and conditions of the photochemical reaction include: 1. 20 drops of 500 microliters (μL) of palladium monochloride (PdCl ) aqueous solution onto a plurality of the zinc oxide nanocolumns 13, the palladium chloride aqueous solution is preferably The concentration is 1 millimolar (1 mM) per liter. 2. Expose the plurality of zinc oxide nanocolumns 13 dripped with the palladium chloride aqueous solution 20 to an ultraviolet light source 30. In the present embodiment, the ultraviolet light source 30 has a wavelength of 365 nanometers (nm) and an intensity of 0.496 mm In watts (mW), the duration of exposure of the plurality of ZnO nanopillars 13 to the ultraviolet light source 30 is 480 seconds. When the zinc oxide nanocolumn 13 reacts with the palladium chloride aqueous solution 20, the plurality of palladium ions (Pd ²⁺ ) in the palladium chloride aqueous solution 20 will react with the plurality of oxygen atoms of the zinc oxide nanocolumn 13, And adsorbed on the surface of the zinc oxide nanocolumn 13, through the irradiation of the ultraviolet light source 30, the plurality of palladium ions are reduced into a plurality of the palladium nanoparticles 14 through a photochemical reaction, and the plurality of the palladium nanoparticles 14 It is formed on the surfaces of a plurality of zinc oxide nanopillars 13 .

Compared with the traditional electron beam evaporation system or thermal evaporation system to sputter the palladium nanoparticles 14 on the surface of the zinc oxide nanopillars 13, the present invention utilizes the photochemical reaction to make the palladium ions Adsorbing on the surface of the zinc oxide nanocolumn 13 from the solution is not only simple in steps and cheap in price, but also conducive to the development of the field emission field.

In the follow-up of the present invention, the difference between the plurality of zinc oxide nanopillars 13 and the plurality of zinc oxide nanopillars 10 adsorbing palladium will be further compared. FIG. 2 is an electromicrograph of a preferred embodiment of the present invention, photographing a plurality of zinc oxide nanopillars 13 and a plurality of palladium-adsorbed zinc oxide nanopillars 10 after they are grown. The left row (a), (b) is the top view of the plurality of zinc oxide nanopillars 13 and the plurality of zinc oxide nanopillars 10 adsorbing palladium; the right row (c), (d) is the plurality of the zinc oxide nanopillars 10 A side view of the ZnO nanopillars 13 and the plurality of ZnO nanopillars 10 adsorbing palladium. After measurement, the average diameters of the plurality of zinc oxide nanopillars 13 and the plurality of zinc oxide nanopillars 10 adsorbing palladium are about 83 and 86 nanometers (nm), and the average lengths are about 2.11 and 2.14 micrometers ( μm). It can be seen from the top views (a) and (b) that the plurality of ZnO nanopillars 13 and the plurality of ZnO nanopillars 10 adsorbing palladium are columns with a hexagonal structure. Wherein, from the enlarged view (e) in the upper right corner of the figure (b), it can be observed that the surface of the zinc oxide nanopillar 10 adsorbing palladium is slightly rough, and it can be known that there are a plurality of the palladium nanoparticles 14 adsorbed on the plurality of the palladium nanoparticles. The surface of the zinc oxide nanopillar 10 that adsorbs palladium.

3 is an analysis diagram of an X-ray diffractometer in a preferred embodiment of the present invention. The X-ray diffractometer is used to detect the characteristics of crystal materials, including the analysis of structural parameters such as structure, phase, and crystal orientation. The X-ray diffraction peak quality is produced by the constructive interference of monochromatic light diffracted from the lattice plane of each sample at a specific angle, and the intensity of the peak is determined by the distribution of atoms in the lattice. It can be seen from the card number 36-1451 in the database of the Joint Committee on Powder Diffraction Standards (JCPDS) that the ratio of zinc oxide is an anisotropic growth hexagonal wurtzite structure, and the obvious (002) peak can indicate that The plurality of zinc oxide nanopillars 13 and the plurality of palladium-adsorbed zinc oxide nanopillars 10 preferentially grow rapidly in the direction of the c-axis, and no other diffraction peaks are found, indicating that there are no impurities.

Fig. 4 is the photoluminescence spectrometer analysis figure of preferred embodiment of the present invention, can find out from the figure that there is a main peak, and this main peak falls on 380nm, and wherein, the peak of 380nm can correspond to this zinc oxide nanocolumn 13 And the near-band gap emission (near-band edge emission) and free exciton recombination (free excitionic recombination) capabilities of the zinc oxide nanopillar 10 of the adsorbed palladium zinc oxide, wherein, the zinc oxide nanopillar 10 of the adsorbed palladium is towards For the ZnO nanopillars 13 have lower peak intensity, which may It is due to photoexcitation of electrons to move from ZnO to the Pd nanoparticles in the conduction band, resulting in a decrease in electron-hole recombination in ZnO, and an increase in the separation phase of photoinduced electrons and holes, resulting in a photon Luminescence intensity decreased.

FIG. 5 is a graph showing the field emission results of a preferred embodiment of the present invention. As shown in the graph, when the current density is 10 ^-5 ampere/cm ² (A/cm ² ), the open electric field value of the zinc oxide nanocolumn 13 is 6.68 Volts/micrometer (V/μm), yet the turn-on electric field value of the ZnO nanocolumn 10 that adsorbs palladium drops to 6.43 volts/micrometer (V/μm), this is because the ZnO nanocolumn 10 that adsorbs palladium provides More carriers are added, making it easier for electrons to tunnel. According to the tunneling current FN formula, it can be known that the value of the field enhancement factor (β) will increase when the turn-on electric field strength decreases, and the enhancement factor can usually be used as the basis for judging whether the component is good or bad. Therefore, it can be known from the data that there is a reason for the adsorption of palladium The ZnO nanocolumn 10 is more suitable as a field emission device.

FIG. 6 is a field emission slope diagram of a preferred embodiment of the present invention. According to the tunneling current FN formula, a field emission slope diagram of ln(J/E ² ) and 1/E is further obtained. The zinc oxide nanocolumn 13 and the The slopes of the field emission of the zinc oxide nanopillars 10 adsorbing palladium are 31.48 and 14.01 respectively. The field emission enhancement factor (β) values of rice pillars 10 are 2546.69 and 5947.07 respectively. From the results, it can be seen that the zinc oxide nanopillars 10 with palladium adsorption significantly improved the enhancement factor (β) value, showing better field emission performance .

As shown in Figure 7, it is a schematic diagram of the field emission energy band measured by an external electric field in a preferred embodiment of the present invention. After the rice column 13 applies an electric field, when the electron e ⁻ obtains energy from a valance band (valance band) and jumps over an energy gap (Eg) to the conduction band (conduction band), the conduction of the zinc oxide nano column 13 The conduction band bends to the Fermi level, creating a quantum well into which electrons e ^- can be stored and tunneled to the vacuum level ) produces a current. However, as shown in Figure 7(a), when the same electric field is given to the ZnO nanocolumn 10 adsorbing palladium, the field emission performance of the ZnO nanocolumn 10 adsorbing palladium is significantly better than that of the ZnO nanocolumn. Mizhu 13, the reasons can be summarized as follows:

1. Since the noble metal palladium can absorb more electrons e ^- , the overall conductivity is enhanced.

2. The heterostructure of the palladium-adsorbed zinc oxide nanocolumn 10 further increases the storage capacity of the quantum well (quantum well), so that more electrons e ^- can be gathered in large quantities in the quantum well (quantum well), The number of electrons ^e- tunneling to the vacuum level increases, and the transfer of current is relatively improved.

10: Zinc Oxide Nanocolumns Adsorbing Palladium

11: Indium tin oxide substrate

12: Zinc oxide film

13: ZnO nanopillars

14: Palladium nanoparticles

15: silver layer

20: palladium chloride aqueous solution

30: UV light source

Claims (5)

A method for manufacturing zinc oxide nanocolumns that adsorb palladium, the steps include: preparing an indium tin oxide substrate, on which a plurality of oxide nanocolumns grow; and using a photochemical reaction to make the complex A plurality of palladium nanoparticles are adsorbed on the surface of the zinc oxide nanocolumns, and the steps of the photochemical reaction include: dropping an aqueous solution of palladium chloride onto the plurality of the zinc oxide nanocolumns; A plurality of the zinc oxide nanocolumns of the palladium aqueous solution are exposed to an ultraviolet light source: the volume of the palladium chloride aqueous solution is 500 microliters, and the concentration of the palladium chloride aqueous solution is 1 millimole per liter; the wavelength of the ultraviolet light source is 365 nm, the intensity of the ultraviolet light source is 0.496 milliwatts; and the duration of exposure of the plurality of zinc oxide nanopillars to the ultraviolet light source is 480 seconds. The process method of zinc oxide nanopillars adsorbing palladium as described in claim 1, using a sputtering method to form a zinc oxide film on the indium tin oxide substrate, the sputtering method includes a radio frequency magnetron sputtering system. According to the process method of zinc oxide nanocolumns adsorbing palladium described in claim 2, the thickness of the zinc oxide film is between 25 nanometers (nm) and 100 nanometers (nm). The process method of zinc oxide nanocolumns adsorbing palladium as described in claim 1 or 2 uses a hydrothermal method to grow a plurality of the zinc oxide nanocolumns, and the steps of the hydrothermal method include: oxidizing the indium tin The object substrate was immersed in a solution of zinc nitrate hexahydrate and cyclohexamethylenetetramine mixed at a molar concentration ratio of 1:1; and reacted at 90° C. for 6 hours. According to the manufacturing method of zinc oxide nanopillars with palladium adsorption as described in claim 1 or 2, the indium tin oxide substrate is plated with a silver layer as a contact electrode.

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