Hole-type transparent conductive praseodymium calcium vanadium oxide film and preparation method thereof

Abstract

The invention discloses a hole-type transparent conductive praseodymium-calcium-vanadium-oxygen film and a preparation method thereof, and relates to the technical field of semiconductor films, and the praseodymium-calcium-vanadium-oxygen transparent conductive film comprises a substrate material and a praseodymium-calcium-vanadium-oxygen layer grown on the surface of the substrate through a pulse laser deposition method. The thin film is simple in preparation process, the prepared thin film has higher carrier mobility and carrier concentration compared with an existing hole-type transparent conductive oxide material, and meanwhile, the thin film has good conductivity and high optical transmittance, so that the thin film shows more excellent transparent conductive performance, and the prepared thin film has a good application prospect. The material has potential application prospects in photoelectric devices.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor thin films, and in particular to a hole-type transparent conductive praseodymium calcium vanadium oxide thin film and a preparation method thereof. Background Art

[0002] Transparent Conducting Oxide (TCO) film is an important optoelectronic material that has both high transmittance in the visible light region and good conductivity. It has been widely used in flat panel displays, solar cells, touch screens, light-emitting diodes and other fields.

[0003] Generally speaking, the transparency and conductivity of materials are incompatible with each other. The existing method for achieving coexistence of transparency and conductivity in a material is to use a wide bandgap semiconductor or insulator as the matrix and introduce carriers through element doping to obtain good conductivity. Based on the above design ideas, people have developed a series of TCO films with high transmittance and high conductivity, such as Sn-doped In2O3 (ITO), Al-doped ZnO (AZO) and F-doped SnO2 (FTO). However, all of the above high-performance TCO films are electronic and can only be used as passive devices in microelectronics and optoelectronic devices, which seriously restricts the application of TCO films. Compared with electronic TCO films, the performance and application of hole-type TCO films are far behind. If high-performance hole-type TCO films can be obtained, active devices such as transparent pn junctions can be constructed, thereby greatly broadening the application field of TCO materials and promoting the development of new optoelectronic devices and related industries.

[0004] Recently, the perovskite structure (ABO3) rare earth vanadium oxide La 2 / 3 Sr 1 / 3 VO3 has been reported as a hole-type TCO thin film material with good transparent conductive properties. The modulation effect of the electron correlation effect in the perovskite structure rare earth vanadium oxide on the valence band of the material is the physical basis of its hole-type conductivity and the key to obtaining hole-type TCO. The A ions are located at the eight corners of the cubic structure, and the B ions are located at the body center of the cubic structure and form a BO6 octahedron with the oxygen ions at the face center. The BO6 octahedron will be twisted, rotated or tilted to a certain extent depending on the radius of the A / B ions, which makes the perovskite structure have a large structural tolerance. Therefore, the perovskite structure rare earth vanadium oxide provides an ideal platform for further improving the transparent conductive properties of hole-type TCO materials. However, how to improve its transparent conductive properties still needs further research and development.

[0005] Pr 0.6 Ca 0.4 VO3 (PCVO) is a typical perovskite rare earth vanadium oxide. 2 / 3Sr 1 / 3 Compared with VO3, PCVO has a higher hole doping amount, so it will have a higher carrier concentration and better transparent conductive properties. However, there is no report on the preparation of PCVO thin films and their transparent conductive properties at home and abroad. Therefore, the present invention believes that it is necessary to carry out in-depth research on hole-type PCVO transparent conductive films and their preparation methods. Summary of the invention

[0006] The object of the present invention is to provide a hole-type transparent conductive praseodymium calcium vanadium oxide film and a preparation method thereof, which has the advantages of high transmittance in the visible light range and good conductivity at room temperature.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film, comprising the following steps:

[0009] A hole-type transparent conductive praseodymium calcium vanadium oxide film, comprising a substrate and praseodymium calcium vanadium oxide (Pr 0.6 Ca 0.4 The ratio of cations in the praseodymium calcium vanadium oxide film is: praseodymium / calcium / vanadium=6 / 4 / 10.

[0010] The praseodymium calcium vanadium oxide transparent conductive film of the present invention is grown by a pulsed laser deposition method, which comprises the following steps:

[0011] Step 1: Prepare praseodymium calcium vanadium oxide target by solid phase reaction method: 11 ), calcium carbonate (CaCO3) and vanadium pentoxide (V2O5) powders are mixed and ground in a molar ratio of 1:4:5, and then the powders are tableted and calcined. The purity of praseodymium oxide is 99.5%, the purity of calcium carbonate is 99%, and the purity of vanadium pentoxide is 99%.

[0012] Step 2: Chemically clean the strontium tantalate lanthanum aluminate ((La, Sr)(Al, Ta) O3, LAST) substrate: ultrasonically clean the substrate in acetone, alcohol, and deionized water in sequence, and then blow dry with nitrogen.

[0013] Step 3: growing a praseodymium calcium vanadium oxide thin film on the strontium tantalum lanthanum aluminate substrate using a pulsed laser deposition method.

[0014] Furthermore, in step 1, the tableting and calcining method is: the ground powder is pressed into a disc with a diameter of 1 inch by a tablet press, calcined at 600°C in a muffle furnace air atmosphere for 10 hours, then ground and tableted again, and calcined at 700°C in a muffle furnace air atmosphere for 10 hours, ground and tableted again, and then calcined at 800oC in a muffle furnace air atmosphere for 10 hours to finally obtain a praseodymium calcium vanadium oxide target.

[0015] Furthermore, in step 2, the LAST substrate is ultrasonically cleaned in acetone, alcohol, and deionized water for 5 minutes in sequence, and then blown dry with nitrogen.

[0016] Further, in step 3, when depositing the praseodymium calcium vanadium oxide film: the temperature of the strontium tantalum lanthanum aluminate substrate is set to 600-700°C, and the vacuum degree of the chamber is maintained at 10 -3 -10 -4 Pa; the laser used is a KrF excimer laser with a laser energy density of 1-2 J / cm 2 , the laser frequency is 1-5Hz, the distance between the target and the substrate is 5-7cm; the rotation rate of the target is 10-20rpm, and the rotation rate of the strontium tantalum lanthanum aluminate substrate is 5-10rpm; the film deposition time is 5-10 minutes, and the film deposition rate under the above process conditions is 1-3nm / min, and the thickness of the obtained praseodymium calcium vanadium oxide film is 5-30nm.

[0017] Furthermore, in step 3, after the deposition of the praseodymium calcium vanadium oxide film is completed, the film is cooled to room temperature at a cooling rate of 5-10°C / min and then taken out.

[0018] Compared with the existing hole-type transparent conductive oxide film, the beneficial effects of the present invention are as follows:

[0019] 1. Excellent performance: The room temperature sheet resistance of the praseodymium calcium vanadium oxide film prepared by the present invention is 438Ω, and the room temperature hole mobility is 4.33cm 2 V -1 s -1 , the hole concentration at room temperature is 2.18×10 21 cm -3 , the optical band gap is about 3.1eV, and the average transmittance in the visible light region is 74.8% (excluding the influence of the substrate). Compared with the existing hole-type transparent conductive oxide materials, the praseodymium calcium vanadium oxide film of the present invention has higher carrier mobility and carrier concentration, and has high optical transmittance while having good conductivity, thus showing more excellent transparent conductive performance and having potential application prospects in optoelectronic devices.

[0020] 2. Simple process: The process of pulsed laser deposition is relatively simple and does not require subsequent post-processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a photograph of the praseodymium calcium vanadium oxide target used in Example 1 and the praseodymium calcium vanadium oxide thin film deposited on a LSAT substrate (5 mm×5 mm);

[0022] Figure 2 is the curve of the change of the sheet resistance of the praseodymium calcium vanadium oxide film deposited on the LSAT substrate in Example 1 with temperature ( Figure 2 (a)) and the Hall effect data curve at 300K (PPMS-9T) ( Figure 2 (b) in the above);

[0023] Figure 3 The optical transmittance data curve obtained by testing the praseodymium calcium vanadium oxide film deposited on the LSAT substrate in Example 1 at a wavelength of 250 to 2000 nm ( Figure 3 (a)) and the optical band gap fitting curve ( Figure 3 (b) in the above);

[0024] Figure 4 is a curve showing the change of the sheet resistance of the praseodymium calcium vanadium oxide film deposited on the LaAlO3 substrate in Comparative Example 1 as a function of temperature;

[0025] Figure 5 This is a curve showing the change of the sheet resistance of the praseodymium calcium vanadium oxide film deposited on the SrTiO3 substrate in Comparative Example 2 with temperature. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described in detail below in conjunction with a specific implementation method. This implementation method is implemented on the premise of the technical solution of the present invention, but the protection scope of this patent is not limited to the implementation method described below.

[0027] Example 1

[0028] This embodiment provides a method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film on a LSAT substrate, comprising the following steps:

[0029] Step 1: Prepare praseodymium calcium vanadium oxide target by solid phase reaction method: praseodymium oxide (Pr6O 11 ) powder, 99% pure calcium carbonate (CaCO3) powder and 99% pure vanadium pentoxide (V2O5) powder are mixed and ground in a molar ratio of 1:4:5. The ground powder is pressed into a 1-inch diameter disc by a tablet press, calcined at 600°C in a muffle furnace for 10 hours, then ground and tableted again, calcined at 700°C in a muffle furnace for 10 hours, ground and tableted again, and then calcined at 800°C in a muffle furnace for 10 hours, and finally a praseodymium calcium vanadium oxide target is obtained.

[0030] Step 2: Chemically clean the LAST substrate: ultrasonically clean the substrate in acetone, alcohol, and deionized water for 5 minutes in sequence, and then blow dry with nitrogen.

[0031] Step 3: Pr 0.6 Ca 0.4 VO3 thin film deposition: LSAT substrate was glued to the heating table with high temperature silver glue and baked at 120℃ for 10 minutes to solidify the silver glue. Then the sample chamber was evacuated to 10 -3 Pa, the substrate temperature rises to 600 ° C, the rotation rate of the target is set to 10 rpm, and the rotation rate of the LSAT substrate is set to 5 rpm. Finally, the laser energy density of the excimer laser is set to 2 J / cm 2 , laser frequency is 5Hz, target substrate distance is 5cm, and film deposition time is 5min. After film deposition, the sample is cooled from 600℃ to room temperature at a cooling rate of 7℃ / min and then taken out. The film deposition rate under the above process conditions is 3nm / min, and the thickness of the obtained PrCaVO film is 15nm.

[0032] Figure 1 ] is a photograph of the praseodymium calcium vanadium oxy target used in Example 1 and the praseodymium calcium vanadium oxy thin film deposited on a LSAT substrate (5 mm x 5 mm).

[0033] Figure 2 is the curve of the change of the sheet resistance of the praseodymium calcium vanadium oxide film deposited on the LSAT substrate in Example 1 with temperature ( Figure 2 (a)) and the Hall effect data curve at 300K (PPMS-9T) ( Figure 2 (b) in the figure.

[0034] Figure 3 The optical transmittance data curve obtained by testing the praseodymium calcium vanadium oxide film deposited on the LSAT substrate in Example 1 at a wavelength of 250 to 2000 nm ( Figure 3 (a)) and the optical band gap fitting curve ( Figure 3 (b) in the figure.

[0035] The test results show that the Pr 0.6 Ca 0.4 The room temperature sheet resistance of VO3 film is 438Ω, and the room temperature hole mobility is 4.33cm 2 V -1 s -1 , the hole concentration at room temperature is 2.18×10 21 cm -3 , the average optical transmittance in the visible light region is 74.8%.

[0036] Comparative Example 1

[0037] This comparative example provides a method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film on a LaAlO3 substrate, comprising the following steps:

[0038] Step 1: Prepare praseodymium calcium vanadium oxide target by solid phase reaction method: praseodymium oxide (Pr6O 11 ) powder, 99% pure calcium carbonate (CaCO3) powder and 99% pure vanadium pentoxide (V2O5) powder are mixed and ground in a molar ratio of 1:4:5. The ground powder is pressed into a 1-inch diameter disc by a tablet press, calcined at 600°C in a muffle furnace for 10 hours, then ground and tableted again, calcined at 700°C in a muffle furnace for 10 hours, ground and tableted again, and then calcined at 800°C in a muffle furnace for 10 hours, and finally a praseodymium calcium vanadium oxide target is obtained.

[0039] Step 2: Chemically clean the lanthanum aluminate (LaAlO3) substrate: ultrasonically clean the substrate in acetone, alcohol, and deionized water for 5 minutes in sequence, and then blow dry with nitrogen.

[0040] Step 3: Pr 0.6 Ca 0.4 VO3 thin film deposition: LaAlO3 substrate was glued to the heating table with high temperature silver glue and baked at 120℃ for 10 minutes to solidify the silver glue. Then the sample chamber was evacuated to 10 -3 Pa, the substrate temperature rises to 600 ° C, the rotation rate of the target is set to 10 rpm, and the rotation rate of the LaAlO3 substrate is set to 5 rpm. Finally, the laser energy density of the excimer laser is set to 2 J / cm 2 , laser frequency is 5 Hz, target substrate distance is 5 cm, and film deposition time is 5 min. After film deposition, the sample is cooled from 600 °C to room temperature at a cooling rate of 7 °C / min and then taken out.

[0041] Figure 4 The sheet resistance of the praseodymium calcium vanadium oxide film deposited on the LaAlO3 substrate in Comparative Example 1 varies with temperature. 0.6 Ca 0.4 The room temperature sheet resistance of the VO3 film is 927Ω, which is much higher than that of Example 1.

[0042] Comparative Example 2

[0043] This comparative example provides a method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film on a SrTiO3 substrate, comprising the following steps:

[0044] Step 1: Prepare praseodymium calcium vanadium oxide target by solid phase reaction method: praseodymium oxide (Pr6O 11) powder, 99% pure calcium carbonate (CaCO3) powder and 99% pure vanadium pentoxide (V2O5) powder are mixed and ground in a molar ratio of 1:4:5. The ground powder is pressed into a 1-inch diameter disc by a tablet press, calcined at 600°C in a muffle furnace for 10 hours, then ground and tableted again, calcined at 700°C in a muffle furnace for 10 hours, ground and tableted again, and then calcined at 800°C in a muffle furnace for 10 hours, and finally a praseodymium calcium vanadium oxide target is obtained.

[0045] Step 2: Chemically clean the SrTiO3 substrate: ultrasonically clean the substrate in acetone, alcohol, and deionized water for 5 minutes in sequence, and then blow dry with nitrogen.

[0046] Step 3: Pr 0.6 Ca 0.4 VO3 thin film deposition: The SrTiO3 substrate was glued to the heating table with high temperature silver glue and baked at 120℃ for 10 minutes to solidify the silver glue. Then the sample chamber was evacuated to 10 -3 Pa, the substrate temperature rises to 600 ° C, the rotation rate of the target is set to 10 rpm, and the rotation rate of the SrTiO3 substrate is set to 5 rpm. Finally, the laser energy density of the excimer laser is set to 2 J / cm 2 , laser frequency is 5 Hz, target substrate distance is 5 cm, and film deposition time is 5 min. After film deposition, the sample is cooled from 600 °C to room temperature at a cooling rate of 7 °C / min and then taken out.

[0047] Figure 5 This is the curve of the change of the sheet resistance of the praseodymium calcium vanadium oxide film deposited on the SrTiO3 substrate in Comparative Example 2 with temperature. 0.6 Ca 0.4 The room temperature sheet resistance of the VO3 film is 1400Ω, which is much higher than that of Example 1.

[0048] In summary, compared with existing hole-type transparent conductive oxide materials, the praseodymium calcium vanadium oxide film of the present invention has higher carrier mobility and carrier concentration, and has high optical transmittance while having good conductivity, thus exhibiting more excellent transparent conductive properties and having potential application prospects in optoelectronic devices.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. All modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A hole-type transparent conductive praseodymium calcium vanadium oxide thin film, characterized in that: A substrate and a praseodymium calcium vanadium oxide Pr grown on the substrate 0.6 Ca 0.4 VO3 thin film.

2. A method for preparing the hole-type transparent conductive praseodymium calcium vanadium oxide thin film according to claim 1, characterized in that: It was grown using pulsed laser deposition.

3. The preparation method according to claim 2, characterized in that: The following steps are involved: Step 1, preparing a praseodymium calcium vanadium oxide target by a solid phase reaction method; Step 2, chemically cleaning the strontium tantalum lanthanum aluminate substrate; Step 3: growing a praseodymium calcium vanadium oxide thin film on the strontium tantalum lanthanum aluminate substrate using a pulsed laser deposition method.

4. The preparation method according to claim 3, characterized in that: In step 1, the praseodymium calcium vanadium oxide target is praseodymium oxide Pr6O 11 The powders of calcium carbonate CaCO3 and vanadium pentoxide V2O5 are mixed in a molar ratio of 1:4:5, ground, tableted and calcined.

5. The method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film according to claim 3, characterized in that: In step 2, the method for chemically cleaning the strontium tantalum lanthanum aluminate substrate is: ultrasonic cleaning in acetone, alcohol, and deionized water in sequence, and then drying with nitrogen.

6. The method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film according to claim 3, characterized in that: In step 3, the temperature of the strontium tantalum lanthanum aluminate substrate is set to 600-700°C when depositing the praseodymium calcium vanadium oxide film, and the vacuum degree of the chamber is maintained at 10 -3 -10 -4 Pa.

7. The method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film according to claim 3, characterized in that: In step 3, the laser used to deposit the PrCaVO thin film is a KrF excimer laser with a laser energy density of 1-2 J / cm 2 , the laser frequency is 1-5Hz, and the distance between the target and the substrate is 5-7cm.

8. The method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film according to claim 3, characterized in that: In step 3, the rotation rate of the target material during the deposition of the praseodymium calcium vanadium oxide film is 10-20 rpm, and the rotation rate of the strontium tantalum lanthanum aluminate substrate is 5-10 rpm.

9. The method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film according to claim 3, characterized in that: In step 3, the film deposition time is 5-10 minutes, and the thickness of the obtained praseodymium calcium vanadium oxide film is 5-30 nm.

10. The method for preparing a hole-type transparent conductive praseodymium calcium vanadium oxide thin film according to claim 3, characterized in that: In step 3, after the deposition of the praseodymium calcium vanadium oxide film is completed, the temperature is lowered to room temperature at a cooling rate of 5-10°C / min and then taken out.

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