High-transparency conductive TCO film and preparation method thereof

Abstract

The invention belongs to the technical field of production of electricity-permeable films, and discloses a preparation method of a high-transparency conductive TCO film, which comprises the following steps: mixing indium oxide and cerium oxide according to a mass ratio of (97-99): (1-3), heating and pressing to obtain an indium cerium oxide target material, and cleaning and drying a glass substrate to obtain a transparent conductive TCO film; depositing indium cerium oxide on the surface of the glass substrate in a sputter coating manner, controlling the thickness of the film to be 80-120nm, and annealing to obtain a high-transparency conductive TCO film; and in the sputtering process, the temperature of the glass substrate is 25-100 DEG C. Through the design, the temperature of the substrate can be more suitable for compact growth of the thin film, so that the carrier mobility of the conductive thin film is further improved, and the carrier mobility of the conductive thin film is further improved, and in addition, the invention further discloses the high-transparency conductive TCO thin film.

Description

Technical Field

[0001] The present application relates to the technical field of electrically transparent film production, and in particular to a highly transparent conductive TCO film and a preparation method thereof. Background Art

[0002] Transparent conductive oxide (TCO) films are widely used in optoelectronic device applications, such as thin-film solar cells, flat panel displays, gas sensors, and organic light-emitting diodes. Among TCO films, ZnO, In2O3, SnO2 and their doping systems have excellent optical and electrical properties, so they have great application prospects in the field of solar cells, such as tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO). However, with the development of thin-film solar cells, the requirements for TCO films are getting higher and higher. The films must have high transmittance and very good conductivity.

[0003] Chinese patent application 202010714648.0 discloses a method for producing a TCO thin film, including the following steps: using a magnetron sputtering coating machine to perform plasma treatment on the first surface of the substrate in a vacuum environment; the plasma treatment is: plasma treatment with a mixed gas; the mixed gas is: one of two mixed gases: a mixed gas formed by an inert gas and an oxidizing gas, and a mixed gas formed by an inert gas and a reducing gas; or, the plasma treatment is: plasma treatment using one of the two mixed gases and the other mixed gas in sequence; using a magnetron sputtering coating machine to coat a TCO thin film on the first surface after plasma treatment in a vacuum environment. This solution achieves a great improvement in the electrical conductivity of the coated TCO thin film without reducing the light transmittance of the TCO thin film.

[0004] Further observation of the scheme shows that "the first surface of the substrate is subjected to plasma treatment; the substrate includes: a silicon wafer, a passivation layer, and a doping layer stacked in sequence; the first surface is the surface of the doping layer away from the passivation layer; the plasma treatment is: plasma treatment with a mixed gas; the mixed gas is one of two mixed gases: a mixed gas formed by an inert gas and an oxidizing gas, and a mixed gas formed by an inert gas and a reducing gas; or, the plasma treatment is: plasma treatment is performed using one mixed gas and another mixed gas of the two mixed gases in sequence, and the two mixed gases are respectively: a mixed gas formed by an inert gas and an oxidizing gas, and a mixed gas formed by an inert gas and a reducing gas."

[0005] However, it can be seen from the proposal that although it discloses the production of TCO thin films using magnetron sputtering, the proposal does not disclose the power of magnetron sputtering and the substrate temperature.

[0006] Chinese patent application 201610915198.5 discloses a method for depositing a transparent conductive film, wherein a DC bias device and an RF power supply or an intermediate frequency power supply are connected in parallel to a target head of a magnetron sputtering system, and the DC bias device is used to adjust the target bias of the sputtered transparent conductive film, and the steps are as follows: the first step is to place the substrate at room temperature without heating, or to heat the substrate so that the substrate temperature is stabilized between room temperature and 700°C; the second step is to introduce argon or a mixture of argon and oxygen into the magnetron sputtering chamber; the third step is to turn on the RF power supply or the intermediate frequency power supply; the fourth step is to turn on the DC bias device so that the target bias is -10 to -300V, and start sputtering the film;

[0007] The solution discloses that the substrate temperature needs to be stabilized to between room temperature and 700°C.

[0008] The problem to be solved by this solution is: how to provide a method for preparing a TCO thin film that is different from the prior art and can prepare a TCO thin film with good electrical properties. Summary of the invention

[0009] The purpose of the present application is to provide a method for preparing a TCO film with good electrical properties. The present application aims to optimize the composition of the TCO film, the proportions of different components, and the substrate temperature during the film growth process, so that the TCO film has both sufficient carriers and good mobility; thereby improving its conductivity and reducing its resistivity.

[0010] To achieve the above object, the present application discloses a method for preparing a highly transparent conductive TCO film, comprising the following steps:

[0011] Step 1: mixing indium oxide and cerium oxide in a mass ratio of 97-99:1-3, heating and pressing to obtain an indium cerium oxide target;

[0012] Step 2: Clean and dry the glass substrate, then deposit the indium cerium oxide in the indium cerium oxide target onto the surface of the glass substrate by sputtering and controlling the film thickness to 80 to 120 nm and annealing to obtain a highly transparent conductive TCO film;

[0013] During the sputtering process of step 2, the temperature of the glass substrate is 25-100°C.

[0014] Preferably, during the sputtering coating process in step 2, the distance between the indium cerium oxide target and the glass substrate is 45 to 100 mm.

[0015] Preferably, during the sputtering coating process in step 2, the sputtering power is 500-700 W and the sputtering time is 5-10 min.

[0016] Preferably, step 2 is performed in a sputtering chamber, and the sputtering chamber is filled with a mixed gas atmosphere of an inert gas, a reducing gas, and an oxidizing gas, and the vacuum degree in the sputtering chamber is 2.5-5.2 mtorr.

[0017] Preferably, the method for making the sputtering chamber a mixed gas atmosphere of an inert gas, a reducing gas, and an oxidizing gas is as follows: a cleaned and dried glass substrate and an indium cerium oxide target are placed at a preset position, and then the vacuum degree in the sputtering chamber is reduced to 5.2×10 -3 ~7.7×10 -3 mtorr;

[0018] Then, a mixed gas of an inert gas and an oxidizing gas and a mixed gas of an inert gas and a reducing gas are introduced into the sputtering chamber to raise the vacuum degree in the sputtering chamber to 2.5 to 5.2 mtorr;

[0019] And the flow ratio of the mixed gas 1 to the mixed gas 2 is 10-20:80-90.

[0020] Preferably, the inert gas is selected from at least one of argon and nitrogen;

[0021] The reducing gas is selected from at least one of hydrogen;

[0022] The oxidizing gas is oxygen.

[0023] Preferably, the mixed gas 1 is a mixed gas 1 of argon and oxygen, and the mass ratio of argon to oxygen is 90-99:1-10;

[0024] The second mixed gas is a mixed gas of argon and hydrogen, and the mass ratio of argon to hydrogen is 93-98:2-7.

[0025] In addition, the present application also discloses a highly transparent conductive TCO film, which is prepared by the above-mentioned method for preparing the highly transparent conductive TCO film.

[0026] Preferably, the highly transparent conductive TCO film has a visible light transmittance of not less than 80%, an infrared light reflectivity of not less than 80%, and a resistivity of not more than 6.00×10 -4 Ω / cm 3 .

[0027] The beneficial effects of this application are:

[0028] The present application optimizes the mass ratio of indium oxide to cerium oxide during the preparation of the transparent conductive TCO film, so that the prepared indium oxide and cerium have a better carrier concentration. At the same time, the present application optimizes the substrate temperature during the preparation process, so that the substrate temperature can be more suitable for the dense growth of the film, thereby further improving the carrier migration ability of the conductive film and thus improving its carrier mobility. By improving the carrier concentration and carrier mobility, the resistivity of the conductive film is reduced. DETAILED DESCRIPTION

[0029] The present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. In the description of the present invention, it should be noted that, if no specific conditions are specified in the embodiments, the conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0030] Example 1

[0031] Step 1: Indium oxide and cerium oxide are mixed in a mass ratio of 98:2, heated and pressed to obtain an indium cerium oxide target;

[0032] Step 2: Place the cleaned and dried glass substrate and indium cerium oxide target at the preset position, and then reduce the vacuum degree in the sputtering chamber to 6.5×10 -3 mtorr;

[0033] Subsequently, a mixed gas of inert gas and oxidizing gas and a mixed gas of inert gas and reducing gas were introduced into the sputtering chamber to raise the vacuum degree in the sputtering chamber to 4.0 mtorr; then, cerium indium oxide was deposited on the surface of the glass substrate by sputtering coating, the film thickness was controlled to 100 nm and annealed to obtain a highly transparent conductive TCO film.

[0034] In the above process, the flow ratio of mixed gas 1 to mixed gas 2 is 15:85;

[0035] The mixed gas 1 is a mixed gas 1 of argon and oxygen, and the mass ratio of argon to oxygen is 95:5;

[0036] The mixed gas 2 is a mixed gas 2 of argon and hydrogen, and the mass ratio of argon to hydrogen is 95:5;

[0037] During the sputtering process, the distance between the indium cerium oxide target and the glass substrate was 75 mm, the sputtering power was 600 W, the sputtering time was 8 min, and the temperature of the glass substrate was 60°C.

[0038] Example 2

[0039] Step 1: Indium oxide and cerium oxide are mixed in a mass ratio of 97:3, heated and pressed to obtain an indium cerium oxide target;

[0040] Step 2: Place the cleaned and dried glass substrate and indium cerium oxide target at the preset position, and then reduce the vacuum degree in the sputtering chamber to 5.2×10 -3 mtorr;

[0041] Subsequently, a mixed gas of inert gas and oxidizing gas and a mixed gas of inert gas and reducing gas were introduced into the sputtering chamber to raise the vacuum degree in the sputtering chamber to 2.5 mtorr; then, cerium indium oxide was deposited on the surface of the glass substrate by sputtering coating, the film thickness was controlled to 80 nm and annealed to obtain a highly transparent conductive TCO film.

[0042] In the above process, the flow ratio of mixed gas 1 to mixed gas 2 is 10:90;

[0043] The mixed gas 1 is a mixed gas 1 of argon and oxygen, and the mass ratio of argon to oxygen is 90:10;

[0044] The mixed gas 2 is a mixed gas 2 of argon and hydrogen, and the mass ratio of argon to hydrogen is 93:7;

[0045] During the sputtering process, the distance between the indium cerium oxide target and the glass substrate was 45 mm, the sputtering power was 500 W, the sputtering time was 10 min, and the temperature of the glass substrate was 60°C.

[0046] Example 3

[0047] Step 1: Indium oxide and cerium oxide are mixed in a mass ratio of 99:1, heated and pressed to obtain an indium cerium oxide target;

[0048] Step 2: Place the cleaned and dried glass substrate and indium cerium oxide target at the preset position, and then reduce the vacuum degree in the sputtering chamber to 7.7×10 -3 mtorr;

[0049] Subsequently, a mixed gas of inert gas and oxidizing gas and a mixed gas of inert gas and reducing gas were introduced into the sputtering chamber to raise the vacuum degree in the sputtering chamber to 5.2 mtorr; then, cerium indium oxide was deposited on the surface of the glass substrate by sputtering coating, the film thickness was controlled to 120 nm and annealed to obtain a highly transparent conductive TCO film.

[0050] In the above process, the flow ratio of mixed gas 1 to mixed gas 2 is 20:80;

[0051] The mixed gas 1 is a mixed gas 1 of argon and oxygen, and the mass ratio of argon to oxygen is 99:1;

[0052] The mixed gas 2 is a mixed gas 2 of argon and hydrogen, and the mass ratio of argon to hydrogen is 98:2;

[0053] During the sputtering process, the distance between the indium cerium oxide target and the glass substrate was 100 mm, the sputtering power was 700 W, the sputtering time was 5 min, and the temperature of the glass substrate was 60°C.

[0054] Example 4

[0055] It is basically the same as Example 1, except that during the sputtering process in step 2, the temperature of the glass substrate is 25°C.

[0056] Example 5

[0057] It is basically the same as Example 1, except that during the sputtering process in step 2, the temperature of the glass substrate is 100°C.

[0058] Example 6

[0059] The method is basically the same as Example 1, except that step 2 is specifically as follows:

[0060] The cleaned and dried glass substrate and indium cerium oxide target were placed in the preset position, and then the vacuum degree in the sputtering chamber was reduced to 6.5×10 -3 mtorr;

[0061] Subsequently, a mixture of inert gas, oxidizing gas and reducing gas is introduced into the sputtering chamber to raise the vacuum degree in the sputtering chamber to 4.0 mtorr; then, cerium indium oxide is deposited on the surface of the glass substrate by sputtering coating, and the film thickness is controlled to 100 nm and annealed to obtain a highly transparent conductive TCO film.

[0062] During the sputtering process, the distance between the indium cerium oxide target and the glass substrate was 75 mm, the sputtering power was 600 W, the sputtering time was 8 min, and the temperature of the glass substrate was 60°C.

[0063] In the mixed gas, the inert gas is argon, the oxidizing gas is oxygen, and the reducing gas is hydrogen;

[0064] The mass ratio of argon, oxygen and hydrogen is 111.8:0.9:5.

[0065] Example 7

[0066] The method is basically the same as Example 1, except that step 2 is specifically as follows:

[0067] The cleaned and dried glass substrate and indium cerium oxide target were placed in the preset position, and then the vacuum degree in the sputtering chamber was reduced to 6.5×10 -3 mtorr;

[0068] Subsequently, a mixture of inert gas and oxidizing gas is introduced into the sputtering chamber to raise the vacuum degree in the sputtering chamber to 4.0 mtorr; then, cerium indium oxide is deposited on the surface of the glass substrate by sputtering coating, and the film thickness is controlled to be 100 nm and annealed to obtain a highly transparent conductive TCO film.

[0069] During the sputtering process, the distance between the indium cerium oxide target and the glass substrate was 75 mm, the sputtering power was 600 W, the sputtering time was 8 min, and the temperature of the glass substrate was 60°C.

[0070] In the mixed gas, the inert gas is argon and the oxidizing gas is oxygen;

[0071] The mass ratio of argon to oxygen is 95:5.

[0072] Comparative Example 1

[0073] The method is basically the same as Example 1, except that the mass ratio of indium oxide to cerium oxide is 95:5.

[0074] Comparative Example 2

[0075] The method is basically the same as Example 1, except that the mass ratio of indium oxide to cerium oxide is 99.9:0.1.

[0076] Comparative Example 3

[0077] It is basically the same as Example 1, except that the temperature of the glass substrate is 10°C.

[0078] Comparative Example 4

[0079] It is basically the same as Example 1, except that the temperature of the glass substrate is 120°C.

[0080] Performance Testing

[0081] 1. Optical performance test: Use a UV spectrophotometer to test the visible-near infrared transmission spectrum of the sample and analyze the transmittance of the sample in the 350nm-750nm and 800-1300nm bands;

[0082] 2. Electrical performance test: Use the Hall effect instrument to test, use the standard sample to calibrate and verify the equipment, and test the sample after the test data reaches the standard sample. The specific test results are shown in Table 1:

[0083] Table 1

[0084]

[0085]

[0086] Result analysis:

[0087] 1. It can be seen from Examples 1-3 that when some process parameters in the preparation process of the TCO thin film are changed, the photoelectric properties of the thin films prepared in Examples 1-3 all have a certain fluctuation trend, but the fluctuation amplitude is relatively small overall;

[0088] 2. It can be seen from Example 1 and Examples 4-5 that when the temperature of the substrate is increased or decreased, the carrier concentration and carrier mobility of the film show an obvious change trend, which makes the resistivity of the film fluctuate more violently. By comparing the resistivity of Example 1 and Examples 4-5, it can be seen that the resistivity of Example 1 is significantly lower than that of Examples 4 and 5. Therefore, the substrate temperature of Example 1 is more advantageous;

[0089] 3. It can be seen from Examples 1 and 6-7 that when the gas atmosphere during the film growth process is changed, the photoelectric properties of the film show a more obvious downward trend compared with Example 1. It is speculated that the reason for this phenomenon may be that when the gas atmosphere is changed, the density of the film may be affected, which in turn affects the refraction of light and the migration of carriers, thereby causing a decline in the photoelectric properties;

[0090] 4. It can be seen from Example 1 and Comparative Examples 1-2 that when the ratio between indium and cerium in the film is changed, the photoelectric properties of the film show a significant downward trend. The reason is that changing the ratio between the raw materials may cause changes in the uniformity of the distribution of components inside the film, the number of defects, etc., and thus affect the optical and electrical properties of the film;

[0091] 5. It can be seen from Example 1 and Comparative Examples 3-4 that when the substrate temperature is greatly changed, the photoelectric performance of the film further declines. At the same time, it can be seen from Example 1, Examples 4-5, and Comparative Examples 3-4 that when the substrate temperature is increased, the carrier concentration of the film is increased, but the mobility is decreased;

[0092] When the substrate temperature is lowered, the carrier concentration of the film decreases and the mobility increases;

[0093] As the temperature gradually increases, the increasing trend of carrier concentration gradually slows down, and as the temperature gradually decreases, the increase in carrier mobility also gradually slows down. Example 1 selects a more advantageous substrate temperature, so that the comprehensive level of carrier concentration and mobility is better than other cases, thereby making the resistivity of Example 1 more advantageous.

[0094] The above embodiments are preferred implementation modes of the present invention, but the implementation modes 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 principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a highly transparent conductive TCO film, characterized in that: The following steps are involved: Step 1: mixing indium oxide and cerium oxide in a mass ratio of 97-99:1-3, heating and pressing to obtain an indium cerium oxide target; Step 2: Clean and dry the glass substrate, then deposit the indium cerium oxide in the indium cerium oxide target onto the surface of the glass substrate by sputtering and controlling the film thickness to 80 to 120 nm and annealing to obtain a highly transparent conductive TCO film; During the sputtering process of step 2, the temperature of the glass substrate is 25-100°C.

2. The method for preparing a highly transparent conductive TCO film according to claim 1, characterized in that: During the sputtering coating process in step 2, the distance between the indium cerium oxide target and the glass substrate is 45 to 100 mm.

3. The method for preparing a highly transparent conductive TCO film according to claim 1, characterized in that: During the sputtering coating process of step 2, the sputtering power is 500-700 W, and the sputtering time is 5-10 min.

4. The method for preparing a highly transparent conductive TCO film according to claim 1, characterized in that: Step 2 is performed in a sputtering chamber, and the sputtering chamber is a mixed gas atmosphere of an inert gas, a reducing gas, and an oxidizing gas, and the vacuum degree in the sputtering chamber is 2.5-5.2 mtorr.

5. The method for preparing a highly transparent conductive TCO film according to claim 4, characterized in that: The method for making the sputtering chamber into a mixed gas atmosphere of inert gas, reducing gas and oxidizing gas is as follows: a cleaned and dried glass substrate and an indium cerium oxide target are placed at a preset position, and then the vacuum degree in the sputtering chamber is reduced to 5.2×10 -3 ~7.7×10 - 3 mtorr; Then, a mixed gas of an inert gas and an oxidizing gas and a mixed gas of an inert gas and a reducing gas are introduced into the sputtering chamber to raise the vacuum degree in the sputtering chamber to 2.5 to 5.2 mtorr; And the flow ratio of the mixed gas 1 to the mixed gas 2 is 10-20:80-90.

6. The method for preparing a highly transparent conductive TCO film according to claim 4, characterized in that: The inert gas is selected from at least one of argon and nitrogen; The reducing gas is hydrogen; The oxidizing gas is oxygen.

7. The method for preparing a highly transparent conductive TCO film according to claim 5, characterized in that: The mixed gas 1 is a mixed gas 1 of argon and oxygen, and the mass ratio of argon to oxygen is 90-99:1-10; The second mixed gas is a second mixed gas of argon and hydrogen, and the mass ratio of argon to hydrogen is 93-98:2-7.

8. A highly transparent conductive TCO film, characterized in that: The highly transparent conductive TCO film is prepared by the preparation method of any one of claims 1-7.

9. The highly transparent conductive TCO film according to claim 8, characterized in that: The highly transparent conductive TCO film has a visible light transmittance of not less than 80%, an infrared light reflectivity of not less than 80%, and a resistivity of not more than 6.00×10 -4 Ω / cm 3 .

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