TCO laminated film and preparation method thereof

Abstract

The invention belongs to the technical field of thin film production, and discloses a TCO laminated thin film, which comprises a zinc oxide bottom layer and an indium oxide top layer, and is characterized in that the zinc oxide bottom layer is a zinc oxide bottom layer doped with an aluminum element and a gallium element; the indium oxide top layer is an indium oxide top layer doped with a tin element; the thickness ratio of the zinc oxide bottom layer to the indium oxide top layer is (50-80): (20-50), extra electron carriers can be effectively introduced through doping of aluminum and gallium, the lattice structure is optimized to a certain extent, the scattering effect of lattice defects on the carriers is reduced, and therefore rich carriers are provided for the whole double-layer film system, and the photoelectric conversion efficiency is improved. The top TCO layer is made of a tin-doped indium oxide material, a channel beneficial to rapid transmission of current carriers is constructed through doping of tin, energy loss and scattering obstruction of the current carriers in the transmission process are effectively reduced by means of the high mobility characteristic of the channel, and in addition, the invention further discloses a preparation method of the TCO laminated film.

Description

Technical Field

[0001] This application relates to the technical field of thin film production, and particularly to a TCO laminated thin film and a preparation method thereof. Background Art

[0002] In the current era of rapid technological development, transparent conductive oxide thin films play a crucial role in optoelectronic device fields such as flat panel displays, solar cells, and touch screens. These application scenarios pose multi-dimensional high-performance requirements for TCO thin films. Among them, high visible light transmittance and low resistivity are two core indicators. High carrier concentration and high mobility are the keys to achieving low resistivity.

[0003] Traditional single-structure TCO thin films encounter technical bottlenecks in the pursuit of improving carrier concentration and mobility. For example, in some TCO thin films with a single composition or structure, when increasing the carrier concentration, the mobility often decreases due to factors such as impurity scattering; conversely, when optimizing the mobility, it is difficult to further increase the carrier concentration. This limitation makes it difficult for single-structure TCO thin films to fully adapt to the growing trend of high-performance and multi-functional development of optoelectronic devices, thus prompting researchers to actively explore new TCO thin film structures and preparation technologies.

[0004] Chinese Patent Application No. 202410717969.4 discloses a laminated thin film and a preparation method thereof. The laminated thin film includes a titanium thin film and an indium-cerium-titanium-tantalum oxide thin film deposited on the titanium thin film; the thickness of the titanium thin film accounts for 5-15% of the total thickness of the laminated thin film. This solution discovers that the laminated thin film within this thickness ratio range not only has a low sheet resistance but also effectively improves the transmittance of the thin film, obtaining a thin film with low resistance, higher transmittance, and lower reflectance by controlling the thickness ratio of the titanium thin film in the laminated thin film.

[0005] However, observing this solution, it can be seen that there are obvious differences between the bottom thin film and the top thin film of this solution and this case.

[0006] Chinese Patent Application No. 200910104849.2 discloses a method for producing TCO thin film glass by float process online. Although this solution reduces the resistance of the TCO thin film, the main reason is to increase the carrier concentration by doping aluminum elements in zinc oxide.

[0007] The problem to be solved by this solution: How to provide a TCO thin film different from the prior art and having good optoelectronic properties. Summary of the Invention

[0008] The objective of this application is to provide a TCO thin film with good optoelectronic properties. Through the doping of aluminum and gallium, additional electron carriers can be effectively introduced, and to a certain extent, the lattice structure can be optimized, reducing the scattering effect of lattice defects on carriers, thereby providing abundant carriers for the entire bilayer thin film system. The top TCO layer is made of indium tin oxide material. Through the doping of tin, a channel conducive to the rapid transmission of carriers is constructed. With its high mobility characteristics, the energy loss and scattering hindrance of carriers during transmission can be effectively reduced; further, through the matching of the thickness ratio between the two, the carrier concentration and mobility can be increased as much as possible, thereby reducing its resistance.

[0009] To achieve the above objective, this application discloses a TCO laminated thin film, including a zinc oxide bottom layer and an indium oxide top layer. The zinc oxide bottom layer is a zinc oxide bottom layer doped with aluminum and gallium elements;

[0010] The indium oxide top layer is an indium oxide top layer doped with tin elements;

[0011] The thickness ratio of the zinc oxide bottom layer to the indium oxide top layer is 50 - 80:20 - 50.

[0012] Preferably, the mass fraction of gallium in the zinc oxide bottom layer is 0.8 - 2.1%, and the mass fraction of aluminum is 1.8 - 3.8%;

[0013] The mass fraction of tin in the indium oxide top layer is 4.5 - 6.8%.

[0014] Preferably, the mass fraction of gallium in the zinc oxide bottom layer is 1.5 - 1.9%, and the mass fraction of aluminum is 2.8 - 3.5%;

[0015] The mass fraction of tin in the indium oxide top layer is 5.8 - 6.5%.

[0016] Preferably, the visible light transmittance of the TCO laminated thin film is not less than 88%, and the resistivity is not higher than 7×10 -4 Ω·cm.

[0017] In addition, this application also discloses a preparation method for preparing the above-mentioned TCO laminated thin film, including the following steps:

[0018] Step 1: Deposit zinc oxide doped with aluminum and gallium elements on the surface of the substrate to obtain an intermediate;

[0019] Step 2: Deposit indium oxide doped with tin elements on the surface of the intermediate to obtain a TCO laminated thin film.

[0020] Preferably, step 1 is specifically as follows: magnetron sputtering zinc oxide doped with aluminum and gallium onto the surface of a cleaned substrate to obtain an intermediate; and the temperature of the substrate is 200-300 °C, the sputtering power is 600-1200 w, the working gas pressure is 0.3-0.8 pa, and the sputtering time is 10-60 s.

[0021] Preferably, step 2 is specifically as follows: magnetron sputtering indium oxide doped with tin element onto the surface of the intermediate to obtain a TCO stacked film; and the temperature of the intermediate is 250-350 °C, the sputtering power is 600-1200 w, the working gas pressure is 0.2-0.6 pa, and the sputtering time is 10-60 s.

[0022] Preferably, the substrate is selected from a glass substrate, a quartz glass substrate, a sapphire substrate, a ceramic substrate, a plastic substrate, or a metal substrate treated with insulation.

[0023] Preferably, the gas atmosphere in step 1 is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 85-95:5-15;

[0024] The gas atmosphere in step 2 is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 90-97:3-10.

[0025] The beneficial effects of the present application are as follows: doping with aluminum and gallium can effectively introduce additional electron carriers, and to a certain extent optimize the lattice structure, reduce the scattering effect of lattice defects on carriers, thereby providing abundant carriers for the entire bilayer film system. The top TCO layer uses indium tin oxide doped with tin. By doping with tin, a channel conducive to the rapid transport of carriers is constructed. With its high mobility characteristics, the energy loss and scattering hindrance of carriers during the transport process are effectively reduced; further, by matching the thickness ratio between the two, the carrier concentration and mobility can be increased as much as possible, thereby reducing its resistance. Specific embodiments

[0026] Next, the embodiments of the present invention will be described clearly and completely in conjunction with the embodiments of the present invention. In the description of the present invention, it should be noted that for those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0027] Example 1

[0028] Pretreatment of the substrate: Place the glass substrate in deionized water for ultrasonic cleaning for 20 ± 5 min, and then transfer the substrate to an acetone solution for ultrasonic cleaning for 15 ± 5 min; then put it into an ethanol solution for ultrasonic cleaning for 10 ± 2 min to further remove residual organic impurities. After cleaning, dry it with high-purity nitrogen;

[0029] Step 1: Use a zinc oxide target doped with aluminum and gallium (where the mass fraction of aluminum is 2% and the mass fraction of gallium is 1%) as the sputtering source. Install it on the target position of the magnetron sputtering equipment. The sputtering gas is a mixed gas of high-purity argon (purity ≥ 99.999%) and oxygen (purity ≥ 99.99%). Keep the volume ratio of argon to oxygen in the equipment at 90:10. Then turn on the equipment and set the sputtering power to 1000 w. Since the equipment has an exhaust end, maintain the working pressure at 0.5 pa by controlling the exhaust volume. At the same time, control the substrate temperature at 250 °C and the deposition time at 50 s. After deposition, an intermediate with a thickness of 70 ± 4 nm is obtained.

[0030] Step 2: Use an indium tin oxide target (where the mass fraction of tin is 5%) as the sputtering source. The sputtering gas is a mixed gas of high-purity argon (purity ≥ 99.999%) and oxygen (purity ≥ 99.99%). Keep the volume ratio of argon to oxygen in the equipment at 95:5. Set the sputtering power at 800 w, keep the working pressure at 0.5 pa, control the temperature of the intermediate at 300 °C, and the deposition time at 25 s. After deposition on the surface of the intermediate, a TCO stacked film with a thickness of 100 ± 3 nm is obtained.

[0031] Examples 2 - 10

[0032] Basically the same as Example 1, except that in the zinc oxide target, the mass fractions of aluminum and gallium, and in the indium oxide target, the mass fraction of tin are as shown in Table 1:

[0033] Table 1

[0034]

[0035]

[0036] Example 11

[0037] Basically the same as Example 1, except that in Step 1, the deposition time is 35 s and the thickness of the intermediate is 50 ± 4 nm, and in Step 2, the deposition time is 40 s and the thickness of the TCO stacked film is 100 ± 4 nm.

[0038] Example 12

[0039] Basically the same as Example 1, except that in Step 1, the deposition time is 60 s and the thickness of the intermediate is 80 ± 3 nm, and in Step 2, the deposition time is 15 s and the thickness of the TCO stacked film is 100 ± 3 nm.

[0040] Comparative Example 1

[0041] Basically the same as Example 1, except that in Step 1, the deposition time is 10 s, the thickness of the intermediate is 15 ± 3 nm, in Step 2, the deposition time is 62 s, and the thickness of the TCO laminate film is 100 ± 3 nm.

[0042] Comparative Example 2

[0043] Step 1: Using a zinc oxide target doped with aluminum and gallium (where the mass fraction of aluminum is 2% and the mass fraction of gallium is 1%) as the sputtering source, install it on the target position of the magnetron sputtering equipment. The sputtering gas is a mixed gas of high-purity argon (purity ≥ 99.999%) and oxygen (purity ≥ 99.99%), and maintain the volume ratio of argon to oxygen in the equipment at 90:10. Then turn on the equipment and set the sputtering power to 1000 w. Since the equipment has an exhaust port, maintain the working pressure at 0.5 pa by controlling the exhaust volume. At the same time, control the substrate temperature at 250 °C and the deposition time at 75 s. After deposition, an aluminum-gallium-doped zinc oxide single-layer film with a thickness of 100 ± 5 nm is obtained.

[0044] Comparative Example 3

[0045] Step 1: Using an indium tin oxide target (where the mass fraction of aluminum is 5%) as the sputtering source, install it on the target position of the magnetron sputtering equipment. The sputtering gas is a mixed gas of high-purity argon (purity ≥ 99.999%) and oxygen (purity ≥ 99.99%), and maintain the volume ratio of argon to oxygen in the equipment at 90 - 97:3 - 10. Set the sputtering power at 800 w, keep the working pressure at 0.5 pa, control the substrate temperature at 300 °C, and the deposition time at 85 s. After deposition, an indium tin oxide single-layer film with a thickness of 100 ± 5 nm is obtained.

[0046] Performance Test:

[0047] 1. Optical Properties

[0048] Use a UV-Vis Spectrophotometer to measure the light absorption rate and transmittance, and the test wavelength range is the visible light region of 350 - 750 nm.

[0049] 2. Electrical Properties

[0050] Use a Four-Point Probe to measure the sheet resistance of the film. In this application, the sheet resistance test is taken at nine points for testing and calculating the average value for recording.

[0051] The carrier concentration, mobility, and resistivity were measured using a Hall Effect Measurement System. The sample was cut to 10*10 mm, and indium alloy was spot-welded at the four corners of the edge for testing and recording. The above test results are shown in Table 1:

[0052] Table 1

[0053]

[0054]

[0055] Result analysis:

[0056] 1. As can be seen from Examples 1-10, the resistivity of Examples 1-10 first decreases and then increases with the gradual increase of the doping amount of aluminum and gallium in the zinc oxide bottom layer and the doping amount of tin in the indium oxide top layer. Further observing Examples 2, 4, 7, and 8, it can be seen that when the co-doping amount of aluminum and gallium is 4.4-5.3 wt%, and the doping amount of tin is 5.8-6.5 wt%, the resistivity of the four is significantly less than that of other examples. It can be seen that the regulation of the doping amount of doping elements can reduce the resistivity of the thin film to a certain extent to improve its electrical properties. At the same time, the above four examples also have better light transmittance than other cases;

[0057] 2. As can be seen from Example 1 and Comparative Example 1, when the thickness of indium oxide is greater than that of zinc oxide, the optoelectronic properties of Comparative Example 1 all decrease. And observing the data of its carrier concentration and mobility, it can be seen that its carrier concentration and carrier mobility are both lower than those of Example 1;

[0058] Further observing Comparative Examples 2-3, it can be seen that when the thin film only contains a zinc oxide layer or an indium oxide layer, the optoelectronic properties of both are lower than those of Example 1. When the thin film is a zinc oxide thin film, although the carrier concentration is slightly increased compared with Example 1, the decrease in mobility is more obvious, which leads to an increase in resistivity;

[0059] When the thin film is an indium oxide thin film, although the mobility does not decrease, the carrier concentration decreases significantly, which leads to an increase in resistivity.

[0060] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A TCO laminated film, characterized in that: It comprises a zinc oxide bottom layer and an indium oxide top layer arranged in sequence from bottom to top, wherein the zinc oxide bottom layer is a zinc oxide bottom layer doped with aluminum and gallium elements; The indium oxide top layer is an indium oxide top layer doped with tin element; The thickness ratio of the zinc oxide bottom layer to the indium oxide top layer is 50-80:20-50.

2. The TCO laminated film according to claim 1, characterized in that: The mass fraction of gallium in the zinc oxide bottom layer is 0.8-2.1%, and the mass fraction of aluminum is 1.8-3.8%; The mass fraction of tin in the indium oxide top layer is 4.5-6.8%.

3. The TCO laminated film according to claim 1, characterized in that: The mass fraction of gallium in the zinc oxide bottom layer is 1.5-1.9%, and the mass fraction of aluminum is 2.8-3.5%; The mass fraction of tin in the indium oxide top layer is 5.8-6.5%.

4. The TCO laminated film according to claim 1, characterized in that: The visible light transmittance of the TCO laminated film is not less than 88%, and the resistivity is not higher than 7×10 -4 Ω·cm.

5. A method for preparing the TCO laminated film according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: depositing zinc oxide doped with aluminum and gallium elements onto the surface of a substrate to obtain an intermediate; Step 2: Depositing indium oxide doped with tin onto the surface of the intermediate to obtain a TCO laminated film.

6. The method for preparing the TCO laminated film according to claim 5, characterized in that: The step 1 is specifically as follows: magnetron sputtering zinc oxide doped with aluminum and gallium elements onto the surface of a cleaned substrate to obtain an intermediate; and the substrate temperature is 200-300° C., the sputtering power is 600-1200W, the working gas pressure is 0.3-0.8Pa, and the sputtering time is 10-60s.

7. The method for preparing a TCO laminated thin film according to claim 5, characterized in that: The step 2 specifically includes: magnetron sputtering indium oxide doped with tin onto the surface of the intermediate to obtain a TCO laminated film.

8. The method for preparing the TCO laminated film according to claim 7, characterized in that: In step 2, the temperature of the intermediate is 250-350° C., the sputtering power is 600-1200 W, the working gas pressure is 0.2-0.6 Pa, and the sputtering time is 10-60 s.

9. The method for preparing a TCO laminated thin film according to claim 5, characterized in that: The substrate is selected from a glass substrate, a quartz glass substrate, a sapphire substrate, a ceramic substrate, a plastic substrate or a metal substrate after insulation treatment.

10. The method for preparing a TCO laminated thin film according to claim 5, characterized in that: The gas atmosphere of step 1 is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 85-95:5-15; The gas atmosphere of step 2 is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 90-97:3-10.

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