A near-infrared transparent conductive film and a preparation method and application thereof
By using a method for preparing In2O3 thin films co-doped with H and Sc, the problem of low transmittance in the near-infrared band of transparent conductive films has been solved, achieving a combination of high conductivity and high transmittance, which is suitable for communication and energy fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTH CHINA UNIV OF TECH
- Filing Date
- 2026-03-31
- Publication Date
- 2026-06-05
AI Technical Summary
Existing transparent conductive films perform well in the visible light band, but have low transmittance in the near-infrared band, making it difficult to meet the needs of optoelectronic devices for expanding the spectral range. This is especially true in fields such as laser communication and photovoltaic cells, where the contradiction between carrier concentration and plasma wavelength leads to a decrease in infrared transmittance.
In2O3 thin films co-doped with H and Sc were prepared by radio frequency magnetron sputtering and vacuum annealing. By controlling the doping amount and process parameters, a polycrystalline transparent conductive film with high carrier mobility and low free carrier concentration was obtained.
It achieves high conductivity and high near-infrared transmittance, making it suitable for large-scale industrial applications in the fields of communication and energy. The transmittance is significantly improved and the performance is adjustable.
Smart Images
Figure CN122158228A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of transparent conductive thin film materials technology, specifically to a near-infrared transparent conductive thin film, its preparation method, and its application. Background Technology
[0002] Transparent conductive films, possessing both excellent conductivity and high transparency, have been widely used in communications (e.g., displays, sensors, and touchscreens) and energy (e.g., photovoltaics, buildings, and window glass). Currently, the theoretical research and application of transparent conductive films in the visible light band are relatively mature. Tin-doped indium oxide (ITO), aluminum-doped zinc oxide (AZO), and fluorine-doped tin oxide (FTO) films have all exhibited excellent photoelectric properties (e.g., ITO films can achieve a transmittance exceeding 80% in the visible light band and a sheet resistance below 20 Ω / □, enabling large-scale commercial applications). However, the transmittance of existing transparent conductive films is limited to the visible light range, while the transmittance in the near-infrared band (780 nm–2526 nm) is very low (cutoff wavelength approximately 1.1 μm; transmittance decreases significantly beyond 1.1 μm).
[0003] As optoelectronic devices continuously expand their spectral range, higher demands are being placed on the transmittance of transparent conductive films in the infrared band. For example, commonly used communication wavelengths in laser communication are 850nm, 1310nm, and 1550nm, and improving the control efficiency of these bands is currently a key research focus. For devices that utilize and control the entire spectrum, such as photovoltaic cells, electrochromic windows, and low-emissivity glasses, improving the transmittance of transparent conductive films in the near-infrared band is beneficial for improving device performance.
[0004] According to the Drood model, transparent conductive films possess a specific plasma wavelength λ. p The calculation formula is as follows: In the formula, ω p Where c is the corresponding plasma frequency, c0 is the speed of light in vacuum, ε0 is the vacuum permittivity, and ε ∞ m is the high-frequency dielectric constant. * λ represents the optically effective carrier mass, and n represents the carrier concentration. Due to the absorption effect of free carriers, wavelengths exceeding λ... pThe incident light is completely reflected by the thin film. As can be seen from the above formula, there is a contradiction between the carrier concentration and the plasma wavelength of a transparent conductive thin film. Increasing the carrier concentration increases the conductivity, but decreases the plasma wavelength and reduces infrared transmittance. This contradiction between infrared optical and electrical properties urgently needs to be resolved. Currently, for traditional wide-bandgap oxide transparent conductive thin films (e.g., ITO and AZO), the conductivity is mainly improved by providing additional free electrons through element doping. Therefore, there is a contradiction between the conductivity and infrared transmittance of the film. Increasing the carrier concentration reduces the plasma wavelength, causing a blue shift in the infrared transmission spectrum and a decrease in transmittance. To ensure the infrared transmittance of the film, it is necessary to reduce the carrier concentration and increase the film's mobility.
[0005] Therefore, developing a transparent conductive film that combines high conductivity and high near-infrared transmittance is of great significance. Summary of the Invention
[0006] The purpose of this invention is to provide a near-infrared transparent conductive film, its preparation method, and its application.
[0007] The technical solution adopted in this invention is: A near-infrared transparent conductive film is an In2O3 film co-doped with H and Sc, wherein the doping amount of H is 1at% to 6at and the doping amount of Sc is 5at% to 15at.
[0008] Preferably, a near-infrared transparent conductive film is an In2O3 film co-doped with H and Sc, wherein the doping amount of H is 1at% to 4at and the doping amount of Sc is 5at% to 10at.
[0009] Preferably, the thickness of the near-infrared transparent conductive film is 10 nm to 150 nm.
[0010] Preferably, the carrier mobility of the near-infrared transparent conductive film is 90 cm⁻¹. 2 ·V -1 ·s -1 ~120cm 2 ·V -1 ·s -1 Free carrier concentration <2.0×10 20 cm -3 Resistivity < 6.0 × 10⁻⁶ -4 Ω·cm, with an average transmittance of >85% in the wavelength range of 800nm to 2500nm.
[0011] A method for preparing a near-infrared transparent conductive film as described above includes the following steps: 1) Radio frequency magnetron sputtering was performed on the substrate using an In2O3:Sc ceramic target. The sputtering gas was Ar, and the reactant gases were O2 and H2, to obtain an amorphous thin film. 2) Vacuum annealing of the amorphous thin film yields a near-infrared transparent conductive thin film with a polycrystalline structure.
[0012] Preferably, the Sc element doping amount of the In2O3:Sc ceramic target material in step 1) is 5 at% to 15 at%.
[0013] Preferably, the substrate in step 1) is one of alkali-free glass substrate, sapphire substrate, and quartz substrate.
[0014] Preferably, the substrate in step 1) has undergone pretreatment, which includes: firstly, ultrasonically cleaning the substrate with acetone, isopropanol and deionized water in sequence, and then drying it.
[0015] Preferably, the time for a single ultrasonic cleaning cycle is 10 min to 20 min.
[0016] Preferably, the process parameters for the radio frequency magnetron sputtering in step 1) include: sputtering power of 45W to 150W, reaction chamber temperature of room temperature, and background vacuum of <1×10⁻⁶. -5 Pa, with a working pressure of 0.2 Pa to 0.5 Pa.
[0017] Preferably, the ratio of the flow rate of O2 to the total flow rate of Ar, O2 and H2 in step 1) is 0 to 0.01:1.
[0018] Preferably, the ratio of the flow rate of H2 to the total flow rate of Ar, O2 and H2 in step 1) is 0.01 to 0.04:1.
[0019] Preferably, the vacuum annealing in step 2) is carried out at a temperature of 250℃ to 350℃ for a time of 30 min to 60 min.
[0020] Preferably, the vacuum annealing in step 2) is performed at a vacuum degree <9×10⁻⁶. -5 The experiment was conducted under the condition of Pa.
[0021] Applications of a near-infrared transparent conductive film as described above in the fields of communication or energy.
[0022] The beneficial effects of the present invention are: the near-infrared transparent conductive film of the present invention has both high conductivity and high near-infrared transmittance, and the performance of the film is easy to control, making it suitable for large-scale industrial applications in the fields of communication and energy.
[0023] Specifically: 1) The near-infrared transparent conductive film of the present invention is doped with H and Sc elements, which improves the carrier mobility of indium oxide material (Sc has a larger bond energy than O, which can reduce the oxygen vacancy content of the prepared film, thereby reducing the scattering of carriers by lattice defects during transport; the introduction of H elements in the deposition process of indium oxide is also beneficial to the improvement of film mobility, and since the radius of hydrogen atoms is small, the resulting scattering cross-section is small, which can reduce the scattering of ionized impurities at the same carrier concentration, thereby improving carrier mobility; according to first-principles calculations, the H elements doped into the lattice mainly act as shallow donor states, which can provide additional free carriers, and H doping can suppress the generation of oxygen defects, which can reduce scattering centers and help improve the mobility of the film), resulting in a transparent conductive film with both high conductivity and high near-infrared transmittance; 2) The near-infrared transparent conductive film of the present invention has good electrical properties, high conductivity, and significantly higher transmittance in the near-infrared band than ITO film. 3) By controlling parameters such as vacuum degree, gas pressure, gas flow rate, sputtering power, and substrate temperature during the radio frequency magnetron sputtering process, the performance of transparent conductive films can be flexibly adjusted. Attached Figure Description
[0024] Figure 1 The figure shows the test results of the electrical properties of transparent conductive films with different H doping amounts.
[0025] Figure 2 XRD patterns of transparent conductive films with different H doping levels.
[0026] Figure 3 The graph shows the transmittance test results of transparent conductive films with different H doping amounts in the near-infrared band. Detailed Implementation
[0027] The present invention will be further explained and described below with reference to specific embodiments.
[0028] Example 1: A near-infrared transparent conductive film, the preparation method of which is as follows: 1) The alkali-free glass substrate was ultrasonically cleaned sequentially with acetone, isopropanol, and deionized water, with each cleaning cycle lasting 10 minutes. It was then dried with compressed air. Radio frequency (RF) magnetron sputtering was then performed on the alkali-free glass substrate using an In₂O₃:Sc ceramic target with a purity of 99.99% and a Sc doping concentration of 5 at%. The RF magnetron sputtering process parameters were as follows: sputtering power of 75 W, reaction chamber temperature at room temperature, and base vacuum degree <1×10⁻⁶. -5The working pressure was 0.3 Pa, the sputtering gas was Ar, and the reactant gases were O2 and H2. The ratio of the flow rate of O2 to the total flow rate of Ar, O2 and H2 was 0.005:1, and the ratio of the flow rate of H2 to the total flow rate of Ar, O2 and H2 was 0.01:1, resulting in an amorphous thin film (thickness of 40 nm). 2) The amorphous thin film was placed at a temperature of 250℃ and a vacuum degree of <9×10⁻⁶. -5 Annealing at Pa for 30 min yields a near-infrared transparent conductive film with a polycrystalline structure.
[0029] The near-infrared transparent conductive film of this embodiment has a mobility of 96.13 cm⁻¹, as tested. 2 ·V -1 ·s -1 The free carrier concentration is 1.57 × 10⁻⁶. 20 cm -3 The resistivity is 4.14 × 10⁻⁶. -4 The average transmittance is 94.90% in the wavelength range of 800 nm to 2500 nm, and the quality factor is 8.33 × 10⁻⁶ Ω·cm. -3 .
[0030] Example 2: A near-infrared transparent conductive film is identical to Example 1 except that the ratio of the flow rate of O2 to the total flow rate of Ar, O2 and H2 in step 1) is adjusted from "0.005:1" to "0.002:1" and the vacuum annealing temperature in step 2) is adjusted from "250℃" to "350℃".
[0031] The near-infrared transparent conductive film of this embodiment was tested and found to have a mobility of 107.40 cm⁻¹. 2 ·V -1 ·s -1 The free carrier concentration is 9.74 × 10⁻⁶. 19 cm -3 The resistivity is 5.97 × 10⁻⁶. -4 The average transmittance is 98.27% in the wavelength range of 800 nm to 2500 nm, and the quality factor is 6.48 × 10⁻⁶ Ω·cm. -3 .
[0032] Example 3: A near-infrared transparent conductive film is identical to Example 1 except that the sputtering power in step 1) is adjusted from "75W" to "150W" and the thickness of the amorphous film in step 1) is adjusted from "40nm" to "100nm".
[0033] The near-infrared transparent conductive film of this embodiment was tested and found to have a mobility of 117.97 cm⁻¹.2 ·V -1 ·s -1 The free carrier concentration is 1.30 × 10⁻⁶. 20 cm -3 The resistivity is 4.08 × 10⁻⁶. -4 The average transmittance (Ω·cm) in the wavelength range of 800 nm to 2500 nm is 91.14%, and the quality factor is 4.96 × 10⁻⁶. -3 .
[0034] Comparative Example 1: A transparent conductive film, the preparation method of which is as follows: 1) Radio frequency magnetron sputtering was performed on an alkali-free glass substrate (pretreated as in Example 1) using an In2O3:Sc ceramic target with a purity of 99.99% and a Sc doping concentration of 5 at%. The process parameters for radio frequency magnetron sputtering were as follows: sputtering power of 75 W, reaction chamber temperature of room temperature, and background vacuum of <1×10⁻⁶. -5 Pa, working pressure is 0.3 Pa, sputtering gas is Ar, reaction gas is O2, the ratio of O2 flow rate to the total flow rate of Ar and O2 is 0.01:1, to obtain an amorphous thin film (thickness is 40 nm). 2) The amorphous thin film was placed at a temperature of 250℃ and a vacuum degree of <9×10⁻⁶. -5 Annealing at Pa for 30 min yields a transparent conductive film with a polycrystalline structure.
[0035] The measured mobility of the transparent conductive film in this comparative example was 81.35 cm⁻¹. 2 ·V -1 ·s -1 The free carrier concentration is 1.10 × 10⁻⁶. 20 cm -3 The resistivity is 6.98 × 10⁻⁶. -4 The average transmittance is 95.26% in the wavelength range of 800 nm to 2500 nm, and the quality factor is 4.06 × 10⁻⁶ Ω·cm. -3 .
[0036] Comparative Example 2: A transparent conductive film is identical to Comparative Example 1, except that the Sc doping amount in step 1) is adjusted from "5 at%" to "10 at%" during preparation.
[0037] The mobility of the near-infrared transparent conductive film in this comparative example was tested to be 65.50 cm⁻¹. 2 ·V -1 ·s -1 The free carrier concentration is 1.06 × 10⁻⁶. 20 cm -3The resistivity is 9.00 × 10⁻⁶. -4 The average transmittance is 98.75% in the wavelength range of 800 nm to 2500 nm, and the quality factor is 4.52 × 10⁻⁶ Ω·cm. -3 .
[0038] The effect of Sc doping amount on the electrical properties of transparent conductive films: Following the procedure in Comparative Example 1, the Sc doping amount of the In2O3:Sc ceramic target was adjusted (0, 5 at%, 10 at%, and 15 at%), and the electrical performance test results of the transparent conductive films with different Sc doping amounts are shown in Table 1. Table 1. Electrical performance test results of transparent conductive films with different Sc doping concentrations
[0039] Note: "Before annealing" and "after annealing" refer to the vacuum annealing process in step 2).
[0040] As shown in Table 1, when the Sc doping amount is 5 at%, the mobility and free carrier concentration of the annealed transparent conductive film are both improved compared with the undoped pure In2O3 film (Sc doping amount is 0). However, as the Sc doping amount is further increased to 10 at% to 15 at%, the free carrier concentration of the transparent conductive film decreases slightly, and the mobility shows a gradual downward trend. The conductivity of the transparent conductive film gradually deteriorates, indicating that an appropriate amount of Sc doping can improve the mobility of the transparent conductive film to a certain extent, thereby optimizing the conductivity of the transparent conductive film.
[0041] The effect of H doping amount on the electrical properties of transparent conductive films: Following the procedure in Example 1, the ratio of H2 flow rate to the total flow rates of Ar, O2, and H2 was adjusted (0, 0.01:1, 0.02:1, 0.04:1, and 0.06:1, i.e., H doping amounts of 0, 1 at%, 2 at%, 4 at%, and 6 at%). The electrical performance test results of the transparent conductive films with different H doping amounts are as follows. Figure 1 As shown in Table 2, the X-ray diffraction (XRD) patterns are as follows: Figure 2 As shown, the transmittance test results in the near-infrared band are as follows: Figure 3 (Commercial ITO oxide transparent conductive film as a control) is shown below: Table 2. Electrical performance test results of transparent conductive films with different H doping concentrations
[0042] Note: "Before annealing" and "after annealing" refer to the vacuum annealing process in step 2).
[0043] Depend on Figure 1 , Figure 2 As shown in Table 2, hydrogen doping can improve the mobility, reduce the sheet resistance, and improve the conductivity of transparent conductive films, while the free carrier concentration only increases slightly. In addition, lower H doping levels (1 at% to 4 at%) are more beneficial to improving the electrical performance of transparent conductive films. Excessive H doping can lead to the transformation of transparent conductive films to an amorphous state, which will result in the deterioration of the conductive film's performance.
[0044] Depend on Figure 3 It can be seen that, compared with commercial ITO oxide transparent conductive films, H and Sc co-doped In2O3 films have higher optical transmittance in the near-infrared band with wavelengths >1000nm, and the average transmittance in the wavelength band of 800nm to 2500nm is increased by 3.68% to 5.18%.
[0045] In summary, this invention achieves a transparent conductive film with both high conductivity and high near-infrared transmittance by doping In2O3 thin films with H and Sc elements.
[0046] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A near-infrared transparent conductive film, characterized in that, It is an In2O3 thin film co-doped with H and Sc, with H doping amount of 1at% to 6at and Sc doping amount of 5at% to 15at.
2. The near-infrared transparent conductive film according to claim 1, characterized in that: The thickness of the near-infrared transparent conductive film is 10nm to 150nm.
3. The near-infrared transparent conductive film according to claim 1 or 2, characterized in that: The carrier mobility of the near-infrared transparent conductive film is 90 cm⁻¹. 2 ·V -1 ·s -1 ~120cm 2 ·V -1 ·s -1 Free carrier concentration <2.0×10 20 cm -3 Resistivity < 6.0 × 10⁻⁶ -4 Ω·cm, with an average transmittance of >85% in the wavelength range of 800nm to 2500nm.
4. A method for preparing a near-infrared transparent conductive film as described in any one of claims 1 to 3, characterized in that, Includes the following steps: 1) Radio frequency magnetron sputtering was performed on the substrate using an In2O3:Sc ceramic target. The sputtering gas was Ar, and the reactant gases were O2 and H2, to obtain an amorphous thin film. 2) Vacuum annealing of the amorphous thin film yields a near-infrared transparent conductive thin film with a polycrystalline structure.
5. The preparation method according to claim 4, characterized in that: Step 1) The Sc element doping amount of the In2O3:Sc ceramic target is 5at% to 15at.
6. The preparation method according to claim 4 or 5, characterized in that: Step 1) The process parameters for the radio frequency magnetron sputtering include: sputtering power of 45W to 150W, reaction chamber temperature of room temperature, and background vacuum of <1×10⁻⁶. -5 Pa, with a working pressure of 0.2 Pa to 0.5 Pa.
7. The preparation method according to claim 4 or 5, characterized in that: In step 1), the ratio of the flow rate of O2 to the total flow rate of Ar, O2 and H2 is 0 to 0.01:1; in step 1), the ratio of the flow rate of H2 to the total flow rate of Ar, O2 and H2 is 0.01 to 0.04:
1.
8. The preparation method according to claim 4, characterized in that: Step 2) The vacuum annealing is carried out at a temperature of 250℃~350℃ for a time of 30min~60min.
9. The preparation method according to claim 4 or 8, characterized in that: Step 2) The vacuum annealing is performed at a vacuum level <9×10 -5 The experiment was conducted under the condition of Pa.
10. An application of a near-infrared transparent conductive film as described in any one of claims 1 to 3 in the fields of communication or energy.