Multi-element doped TCO film

Abstract

The invention belongs to the technical field of thin film production, and discloses a multi-element doped TCO thin film which is obtained by deposition of an indium oxide target material containing doped elements or co-deposition of the indium oxide target material and the target material containing the doped elements. The doping element is selected from at least one of a tin element, a titanium element, a cerium element, a gallium element, a zirconium element and a tantalum element, and at least comprises the tin element; the mass ratio of the indium oxide to the oxide containing the doping element is (98-99): (0.2-3), and the crystal structure and the carrier concentration of the thin film are improved through the design, so that the photoelectric property of the thin film is improved.

Description

Technical Field

[0001] The present application relates to the technical field of thin film production, and in particular to a multi-element doped TCO thin film. Background Art

[0002] Transparent conductive oxide (TCO) films are widely used in flat panel displays, solar cells and other fields. However, with the development of technology, higher requirements are placed on the performance of TCO films. TCO films doped with a single element often cannot meet the comprehensive requirements of high conductivity and high transparency. Therefore, the development of a multi-element doped TCO film has become a research hotspot. By doping with appropriate elements, the carrier concentration in the film can be increased. For example, doping tin in ITO film can effectively improve its conductivity and meet the requirements of high conductivity of transparent conductive electrodes such as liquid crystal displays.

[0003] The article “The Effect of Preparation Conditions on the Transparent Conductivity of Gallium-doped Zinc Oxide Films” published in the Journal of Henan University (Natural Science Edition) Vol. 42 No. 6 pointed out that the gallium-doped zinc oxide film achieved a 0.84×10 -4 The low resistivity of Q·cm and visible light transmittance greater than 90% and its optical band gap also increases to a certain extent with the increase of annealing temperature;

[0004] However, the gallium-doped film in this scheme is a zinc oxide film, not an indium tin oxide film. At the same time, this scheme believes that the principle that gallium doping can improve the zinc oxide film is that the doping of the third main group element can increase the concentration of free electrons, and compared with other doping elements, Ga 3+ Ionic Radius and Zn 2+ The ionic radius is very close, and the bond lengths of Zn-O and Ga-O are slightly different, 0.197nm and 0.192nm respectively. Even at high doping concentrations, the effect of doping on ZnO lattice distortion is small. On the other hand, during the deposition of the film, Ga element is not easily oxidized;

[0005] It can be seen that the key to gallium doping in this scheme to improve the photoelectric properties of zinc oxide film is that gallium is a third-group element and its ionic radius is relatively close to that of zinc, so it is not easy to cause lattice distortion and defects, thereby affecting resistance. Compared with indium, the ionic radius difference between gallium and zinc is obviously smaller. Therefore, it is difficult to predict whether the photoelectric performance can be improved after gallium is doped into indium oxide.

[0006] The problem that this solution needs to solve is: how to provide a TCO film with good photoelectric properties. Summary of the invention

[0007] The object of the present application is to provide a TCO thin film with good optoelectronic performance. Through doping with multiple elements, parameters such as the crystal structure and carrier concentration of the thin film are optimized, effectively improving the performance of the device, reducing energy consumption, and reducing the absorption of the thin film in the visible light region, thereby increasing its visible light transmittance.

[0008] To achieve the above object, the present application discloses a multi-element doped TCO thin film, which is obtained by depositing an indium oxide target containing doping elements or co-depositing an indium oxide target and an oxide target containing doping elements;

[0009] The doping elements are selected from at least one of tin element, titanium element, cerium element, gallium element, zirconium element, tantalum element and at least contain tin element;

[0010] And the mass ratio of indium oxide to the oxide containing doping elements is 98-99:0.2-3.

[0011] Preferably, the multi-element doped TCO thin film is obtained by depositing an indium oxide target containing doping elements, and the doping elements include tin element and titanium element.

[0012] Preferably, the mass ratio of indium oxide to tin oxide and titanium oxide is 98-99:0.01-0.05:0.1-0.6.

[0013] Preferably, the doping elements in the indium oxide target containing doping elements are tin element, titanium element, tantalum element, cerium element, gallium element.

[0014] Preferably, the mass ratio of indium oxide to tin oxide, titanium oxide, tantalum oxide, cerium oxide and gallium oxide is 98-99:0.01-0.05:0.1-0.6:0.1-0.6:0.1-0.8:0.1-0.6.

[0015] Preferably, the multi-element doped TCO thin film is obtained by depositing an indium oxide target containing doping elements, and the deposition method is specifically:

[0016] Clean the indium oxide target containing doping elements, and then sputter and deposit it on the surface of the substrate in a mixed gas environment of argon, oxygen and hydrogen, and then anneal to obtain the multi-element doped TCO thin film;

[0017] And the mass ratio of argon to oxygen and hydrogen in the mixed gas is 90-100:0.1-3:0.1-1.6.

[0018] Preferably, the multi-element doped TCO thin film is obtained by co-depositing an indium oxide target and an oxide target containing doping elements, and the deposition method is specifically:

[0019] Clean the indium oxide target and the target containing doping elements, and then co-sputter and deposit them on the surface of the substrate in an environment of a mixed gas of argon, oxygen, and hydrogen, and then anneal to obtain a multi-element doped TCO film;

[0020] And the mass ratio of argon to oxygen and hydrogen in the mixed gas is 90-100:0.1-3:0.1-1.6.

[0021] Preferably, the substrate is selected from glass, quartz, sapphire, silicon, polyimide or polyethylene terephthalate.

[0022] Preferably, the annealing operation is specifically: place the film deposited on the substrate surface in an environment of 200-300 °C for annealing for 30-60 min, and then obtain a multi-element doped TCO film.

[0023] Preferably, the light transmittance of the multi-element doped TCO film at 300-1300 nm is not less than 88%, the transmittance in the visible light region is not less than 88%, and the resistivity is not higher than 3.2×10 -4 Ω / cm 3 .

[0024] The beneficial effects of this application are:

[0025] In this application, through the doping of multiple elements, electrons are injected into the material through element doping and regulated to achieve a cascade effect of energy band optimization (downward shift of the conduction band) to achieve scattering suppression (grain refinement), and finally manifested as excellent optoelectronic properties such as high light transmittance and low resistance of the TCO film. By synergistically optimizing the synergistic effect between multiple elements, parameters such as the crystal structure and carrier concentration of the film are optimized, and in application scenarios such as flat panel displays and solar cells, the performance of the device can be effectively improved, energy consumption can be reduced, and a broader application prospect can be provided; on the other hand, by introducing doping elements to adjust the energy band structure and optical properties of the TCO film, the absorption in the visible light region is reduced, thereby improving its visible light transmittance. Specific Embodiments

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

[0027] Example 1

[0028] Step 1: Ultrasonically clean the glass substrate successively with deionized water, acetone, and ethanol, then dry it with nitrogen, and place the treated glass substrate as a substrate in the waiting chamber;

[0029] Step 2: Pump the sputtering chamber to a vacuum of (6±1)×10 -6 torr.

[0030] Step 3: Continuously introduce argon, oxygen, and hydrogen into the sputtering chamber with the mass ratio of argon to oxygen and hydrogen being 90:3:1.6. Adjust the gas pressure in the sputtering chamber to 3 mtorr (since the equipment is equipped with an exhaust device, the gas pressure in the sputtering chamber can be regulated by controlling the exhaust volume). Subsequently, pre-sputter and clean the surface of the target (indium tin oxide target doped with tin element, where the mass ratio of indium oxide to tin oxide is 98.5:0.64) with a sputtering power of 800 w for 50 min to remove surface impurities;

[0031] Step 4: Under the condition that the temperature of the substrate (glass substrate) is 25 °C by a magnetron sputtering coater, set the power to 800 w, set the target distance to 90 mm, and adjust the working gas pressure to 3.5 mtorr. At this time, the mass ratio of argon to oxygen and hydrogen in the mixed gas is 90:3:1.6 and is still continuously introduced. Then turn on the power supply and deposit for 60 s. Subsequently, anneal the film deposited on the substrate surface in an environment of 200 °C for 60 min to obtain a multi-element doped TCO film.

[0032] Example 2

[0033] Step 1: Ultrasonically clean the glass substrate successively with deionized water, acetone, and ethanol, then dry it with nitrogen, and place the treated glass substrate as the substrate into the waiting chamber;

[0034] Step 2: Pump the sputtering chamber to a vacuum of (6±1)×10 -6 torr.

[0035] Step 3: Continuously introduce argon, oxygen, and hydrogen into the sputtering chamber with the mass ratio of argon to oxygen and hydrogen being 100:0.1:0.1. Adjust the gas pressure in the sputtering chamber to 3 mtorr (since the equipment is equipped with an exhaust device, the gas pressure in the sputtering chamber can be regulated by controlling the exhaust volume). Subsequently, pre-sputter and clean the surface of the target (indium tin oxide target doped with tin element, where the mass ratio of indium oxide to tin oxide is 98:3) with a sputtering power of 1200 w for 30 min to remove surface impurities;

[0036] Step 4: Under the condition that the temperature of the substrate (glass substrate) is 25 °C by a magnetron sputtering coater, set the power to 1200 w, set the target distance to 50 mm, and adjust the working gas pressure to 6 mtorr. At this time, the mass ratio of argon to oxygen and hydrogen in the mixed gas is 100:0.1:0.1 and is still continuously introduced. Then turn on the power supply and deposit for 60 s. Subsequently, anneal the film deposited on the substrate surface in an environment of 300 °C for 30 min to obtain a multi-element doped TCO film.

[0037] Example 3

[0038] Step 1: The glass substrate is ultrasonically cleaned successively with deionized water, acetone, and ethanol, then dried with nitrogen, and the treated glass substrate is placed as a substrate in the waiting chamber;

[0039] Step 2: The sputtering chamber is evacuated to (6 ± 1)×10 -6 torr.

[0040] Step 3: Argon, oxygen, and hydrogen are continuously introduced into the sputtering chamber with the mass ratio of argon to oxygen and hydrogen being 95:2:1, and the air pressure in the sputtering chamber is adjusted to 3 mtorr (since the equipment is equipped with an exhaust device, the air pressure in the sputtering chamber can be regulated by controlling the exhaust volume). Subsequently, the target (indium tin oxide target doped with tin element, where the mass ratio of indium oxide to tin oxide is 99:0.2) is pre-sputter cleaned for 35 min at a sputtering power of 1000 w to remove surface impurities;

[0041] Step 4: Using a magnetron sputtering coater, under the condition that the temperature of the substrate (glass substrate) is 25 °C, the power is set to 1000 w, the target distance is set to 70 mm, and the working air pressure is adjusted to 5 mtorr. At this time, the mass ratio of argon to oxygen and hydrogen in the mixed gas is 95:2:1 and is still continuously introduced. Subsequently, the power supply is turned on and deposition is carried out for 60 s. Then, the film deposited on the substrate surface is annealed at 250 °C for 50 min to obtain a multi-element doped TCO film.

[0042] Example 4

[0043] It is basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced with an indium tin oxide target doped with tin element and titanium element, and the mass ratio of indium oxide to tin oxide and titanium oxide in the target is 98.5:0.04:0.6.

[0044] Example 5

[0045] It is basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced with an indium tin oxide target doped with tin element and tantalum element, and the mass ratio of indium oxide to tin oxide and tantalum oxide in the target is 98.5:0.04:0.6.

[0046] Example 6

[0047] It is basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced with an indium tin oxide target doped with tin element and cerium element, and the mass ratio of indium oxide to tin oxide and cerium oxide in the target is 98.5:0.04:0.6.

[0048] Example 7

[0049] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium tin oxide target doped with tin element, gallium element, and the mass ratio of indium oxide to tin oxide and gallium oxide in the target is 98.5:0.04:0.6.

[0050] Example 8

[0051] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium tin oxide target doped with tin element, zirconium element, and the mass ratio of indium oxide to tin oxide and zirconium oxide in the target is 98.5:0.04:0.6.

[0052] Example 9

[0053] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium tin oxide target doped with tin element, titanium element, tantalum element, cerium element, and the mass ratio of indium oxide to tin oxide, titanium oxide, tantalum oxide, cerium oxide in the target is 98.5:0.04:0.2:0.2:0.2.

[0054] Example 10

[0055] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium tin oxide target doped with tin element, titanium element, tantalum element, cerium element, gallium element, and the mass ratio of indium oxide to tin oxide, titanium oxide, tantalum oxide, cerium oxide, gallium oxide in the target is 98.5:0.04:0.15:0.15:0.15:0.15.

[0056] Example 11

[0057] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium tin oxide target doped with tin element, titanium element, tantalum element, cerium element, zirconium element, and the mass ratio of indium oxide to tin oxide, titanium oxide, tantalum oxide, cerium oxide, zirconium oxide in the target is 98.5:0.04:0.15:0.15:0.15:0.15.

[0058] Comparative Example 1

[0059] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium tin oxide target doped with titanium element, tantalum element, cerium element, and the mass ratio of indium oxide to titanium oxide, tantalum oxide, cerium oxide in the target is 98.54:0.2:0.2:0.2.

[0060] Comparative Example 2

[0061] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium gallium oxide target doped with gallium element, and the mass ratio of indium oxide to gallium oxide in the target is 98.54:0.6.

[0062] Comparative Example 3

[0063] Basically the same as Example 1, except that the indium tin oxide target doped with tin element is replaced by an indium zirconium oxide target doped with zirconium element, and the mass ratio of indium oxide to zirconium oxide in the target is 98.54:0.6.

[0064] Performance Test:

[0065] 1. Optical Properties

[0066] The light absorption rate and transmittance were measured using a UV-Vis Spectrophotometer, and the test wavelength range was 800 - 1300 nm in the infrared region and 350 - 750 nm in the visible light region.

[0067] 2. Electrical Properties

[0068] 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

[0069] Table 1

[0070]

[0071]

[0072] Performance Test:

[0073] 1. It can be seen from Examples 1 - 3 that when the parameters in the preparation process of the TCO film are slightly adjusted for cerium, the optoelectronic properties of the TCO film only show small fluctuations. It can be seen that slightly adjusting the process parameters will not have an obvious impact on the quality of the film;

[0074] 2. It can be seen from Examples 4 - 12 that first, in Examples 4 - 8, co-doping of tin element and other metal elements was carried out respectively. It can be seen that Examples 4 - 8 have more suppression on resistivity compared with Examples 1 - 3. Among them, in Example 7, when tin and gallium are co-doped, the suppression of resistivity is mainly achieved by improving the mobility;

[0075] Further observation of Example 9 shows that when co-doped with tin, titanium, tantalum, and cerium, the carrier concentration is further increased. It is speculated that the reason may be that in Example 9, doping with multiple high-valence elements provides more carriers, and due to the increase in the types of doping elements, the overly severe lattice distortion caused by excessive single elements is reduced, thereby enabling the mobility to maintain a relatively high level, and thus reducing the resistivity.

[0076] When gallium is further added to the doping elements in Example 10, the resistance of Example 10 shows an obvious downward trend compared with Example 9; and its mobility also has an obvious increase. The reason may be that the ionic radius of gallium is relatively small, and when combined with other elements, it further reduces the number of lattice defects, thereby enhancing the mobility of the material. At the same time, the material still maintains a relatively high carrier concentration, thereby significantly increasing the resistivity.

[0077] When gallium is replaced by zirconium, due to the relatively large ionic radius of zirconium, it is difficult to achieve a relatively high mobility, but it still further increases the number of carriers, thereby suppressing the resistivity.

[0078] It can be seen from Comparative Examples 1-3 that when tin is missing in the doping elements, it is difficult for the material to maintain a relatively high carrier concentration. It can be seen that tin is a key factor for reducing the resistivity of the thin film.

[0079] 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 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 multi-element doped TCO film, characterized in that: Obtained by depositing an indium oxide target containing a doping element or co-depositing an indium oxide target and an oxide target containing a doping element; The doping element is selected from at least one of tin, titanium, cerium, gallium, zirconium and tantalum and at least includes tin; The mass ratio of indium oxide to the oxide containing the doping element is 98-99:0.2-3.

2. The multi-element doped TCO thin film according to claim 1, characterized in that: The multi-element doped TCO film is obtained by depositing an indium oxide target material containing doping elements, and the doping elements include tin and titanium.

3. The multi-element doped TCO thin film according to claim 2, characterized in that: The mass ratio of indium oxide to tin oxide and titanium oxide is 98-99: 0.01-0.05: 0.1-0.

6.

4. The multi-element doped TCO thin film according to claim 2, characterized in that: The doping element in the indium oxide target material containing doping elements is tin, titanium, tantalum, cerium and gallium.

5. The multi-element doped TCO thin film according to claim 4, characterized in that: The mass ratio of indium oxide to tin oxide, titanium oxide, tantalum oxide, cerium oxide and gallium oxide is 98-99: 0.01-0.05: 0.1-0.6: 0.1-0.6: 0.1-0.8: 0.1-0.

6.

6. The multi-element doped TCO thin film according to claim 1, characterized in that: The multi-element doped TCO film is obtained by depositing an indium oxide target containing doping elements. The specific deposition method is as follows: The indium oxide target containing the doped element is cleaned, and then placed in a mixed gas environment of argon, oxygen and hydrogen for sputtering deposition onto the substrate surface, and then annealed to obtain a multi-element doped TCO film; The mass ratio of argon to oxygen and hydrogen in the mixed gas is 90-100: 0.1-3: 0.1-1.

6.

7. The multi-element doped TCO thin film according to claim 1, characterized in that: The multi-element doped TCO film is obtained by co-depositing an indium oxide target and an oxide target containing doping elements, and the deposition method is specifically as follows: The indium oxide target and the target containing the doping element are cleaned, and then co-sputtered and deposited on the substrate surface in a mixed gas environment of argon, oxygen and hydrogen, and then annealed to obtain a multi-element doped TCO film; The mass ratio of argon to oxygen and hydrogen in the mixed gas is 90-100: 0.1-3: 0.1-1.

6.

8. The multi-element doped TCO thin film according to claim 6, characterized in that: The substrate is selected from glass, quartz, sapphire, silicon, polyimide or polyethylene terephthalate.

9. The multi-element doped TCO thin film according to claim 7, characterized in that: The annealing operation is specifically as follows: placing the thin film deposited on the substrate surface in an environment of 200 to 300° C. and annealing for 30 to 60 minutes, and then obtaining a multi-element doped TCO thin film.

10. The multi-element doped TCO thin film according to claim 1, characterized in that: The multi-element doped TCO film has a light transmittance of not less than 88% in the range of 300 to 1300 nm, a transmittance in the visible light region of not less than 88%, and a resistivity of not more than 3.2×10 -4 Ω / cm 3 .

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