A high-conductivity p-type amorphous transparent conductive thin film material and a preparation method thereof

Abstract

The present invention discloses a high-conductivity p-type amorphous transparent conductive thin film material and a preparation method thereof, belonging to the field of optoelectronic materials. Aiming at the problem of low p-type conductivity of existing transparent conductive thin film materials in the amorphous state, the present invention obtains an amorphous transparent thin film with extremely high p-type conductivity based on copper iodide sulfide material, and its molecular formula is CuI x S y . The thin film is synthesized by a chemical method, and the transparency and conductivity of the thin film are regulated by the synergistic effect of two heavy ions, sulfur and iodine. The prepared p-type amorphous CuI x S y thin film not only has a conductivity comparable to that of commercial ITO transparent conductive thin film, but also has high transparency in the visible light range. The raw materials adopted in the present invention are low in cost, the preparation technology is simple and suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic materials, and relates to a highly conductive p-type amorphous transparent conductive thin film based on copper iodide sulfide and a method for its large-scale production. Background Art

[0002] Amorphous transparent conductive thin films are key constituent materials for optoelectronic, transparent, and flexible electronic devices, such as the transparent electrode layer for optoelectronic and flexible devices, the channel layer of thin film field effect transistors, the transparent conductive layer of electromagnetic shielding and low-emissivity films, etc. Due to the amorphous characteristics, such thin films are suitable for low-temperature large-area uniform preparation on various substrates including glass and polymers, and have higher rollability than crystalline materials.

[0003] In practical applications, transparent conductive thin films usually require a conductivity higher than 10 3 S / cm, such as commercially available indium-doped tin oxide (ITO). However, most of the existing amorphous transparent conductive materials are n-type conductive, with poor p-type conductivity, and the hole conductivity is usually below 10 S / cm, far from meeting the conductivity requirements of practical transparent conductive thin films. Therefore, the lack of highly conductive p-type amorphous transparent conductive materials is a major bottleneck in the development of current transparent conductive technologies. Summary of the Invention

[0004] Aiming at the problem of low p-type conductivity of existing amorphous transparent conductive thin film materials, the purpose of the present invention is to provide a highly conductive p-type amorphous transparent conductive thin film material based on copper iodide sulfide (CuI x S y ) and a preparation method thereof.

[0005] A highly conductive p-type amorphous transparent conductive thin film material of the present invention has a hole carrier concentration of about 10 22 cm -3 , and when the thickness is 50 - 300 nm, the visible light transmittance can exceed 70%, and the p-type conductivity can be continuously adjusted within the range of 1000 - 5000 S / cm.

[0006] A highly conductive p-type amorphous transparent conductive thin film material of the present invention has copper iodide sulfide as the main component, and its molecular formula is CuI x S y , where 0 < x / y < 0.25; when the x / y value is higher than 0.25, polycrystalline phases of the CuI zinc blende structure are likely to precipitate, destroying the single amorphous structure of the thin film.

[0007] A preparation method of a high-conductivity p-type amorphous transparent conductive thin film material of the present invention uses a metal copper or copper nitride thin film grown at room temperature on any substrate as an initial precursor material, and then iodine and sulfur are used as reaction materials for iodine sulfidation synthesis preparation.

[0008] In the preparation process of the precursor material, a conventional thermal evaporation or magnetron sputtering method is used to prepare a metal copper or copper nitride thin film at room temperature on any substrate, and the obtained thin film thickness is 20-100 nm.

[0009] The CuI x S y amorphous thin film components and electrical properties obtained from the two precursor materials of metal copper and copper nitride thin films are basically the same; compared with metal copper, the surface of the CuI x S y amorphous thin film obtained from copper nitride is smoother, so the light transmittance is higher.

[0010] In the iodine sulfidation process, there are two paths with basically the same results:

[0011] Path A: First, place the precursor material together with 5-20 g of sulfur particles in a closed glassware, heat to 150-200 °C, hold for 2-20 min, and cool to obtain a Cu 2-x S amorphous thin film (0<x<1) with a thickness of 50-300 nm; then, place this amorphous Cu 2-x S thin film together with 5-20 g of iodine particles in a closed glassware, and keep it at room temperature for 2-20 min to obtain a CuI x S y amorphous thin film.

[0012] Path B: First, place the precursor material together with 5-20 g of iodine particles in a closed glassware, and keep it at room temperature for 2-20 min to obtain a CuI polycrystalline thin film with a thickness of 50-300 nm; then, place this CuI polycrystalline thin film together with 5-20 g of sulfur particles in a closed glassware, heat to 150-200 °C, hold for 2-20 min, and cool to obtain a CuI x S y amorphous thin film.

[0013] Both Path A and Path B can be carried out in the atmosphere without an inert protective gas or a vacuum environment. By adjusting the iodine sulfidation time respectively, the control of the iodine and sulfur component ratios in the CuI x S y amorphous thin film can be realized, so that the iodine-sulfur molar ratio satisfies 0<x / y<0.25.

[0014] The material CuI of the present invention x S y The amorphous thin film is a homogeneous solid solution formed by mixing two p-type wide-bandgap semiconductors Cu 2-x S and CuI. Although there are multiple crystal phases of Cu 2-x S, the Cu 2-x S thin film prepared by the method described in the present invention is amorphous, with a bandgap width of 2.0 - 2.5 eV. Its advantage lies in its extremely high intrinsic hole carrier concentration, which can reach 10 22 cm -3 order of magnitude. CuI exhibits a γ-phase cubic zinc blende structure at room temperature (< 390 o °C), with a bandgap width of approximately 3.1 eV. Its advantage is that it can be transparent throughout the visible light wavelength range, and its low hole effective mass (0.30m 0 ₀) ensures a high hole mobility. The solid solution CuI x S y formed by these two p-type semiconductor materials also exhibits intrinsic p-type conductivity, combining the above electrical and optical performance advantages of Cu 2-x S and CuI. Especially in the amorphous disordered structure, when the two negatively charged heavy ions, sulfur and iodine, and the positively charged light ion, cuprous, are randomly combined, a synergistic effect occurs. The outermost electron clouds of sulfur ions and iodine ions overlap with each other to form the valence band top structure, that is, the transport channel for hole carriers. This transport channel is not affected by lattice distortion, so it can ensure the rapid conduction of hole carriers in the amorphous state. Considering the above factors, the CuI x S y amorphous thin film can simultaneously possess excellent visible light transparency and hole conductivity.

[0015] The amorphous transparent p-type CuI x S y thin film of the present invention solves the problem of low p-type conductivity of traditional transparent conductive materials. Its high conductivity of 1000 - 5000 S / cm can be comparable to that of commercial ITO transparent conductive thin films.

[0016] The CuI x S y thin film of the present invention has a low preparation cost, is easy to form a large-area film, is suitable for large-scale production, and its relatively low synthesis temperature is suitable for integration on other semiconductor materials.

[0017] The CuI x S y thin film of the present invention has a significant cost advantage in its raw materials such as copper, iodine, and sulfur compared to the expensive indium metal used in commercial ITO transparent conductive thin films. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 For three embodiments of the present invention, CuI x S y Visible light transmittance spectrum of the amorphous thin film material;

[0019] Figure 2 For three embodiments of the present invention, CuI x S y Graph of the p-type resistivity of the amorphous thin film material varying with the x / y value. Detailed implementation manners

[0020] The present invention provides a highly conductive p-type amorphous transparent conductive thin film material, the composition of which is copper iodide sulfide (CuI x S y ) thin film, where 0 < x / y < 0.25. When the thickness is 50 - 300 nm, the visible light transmittance of this thin film can exceed 70%, and the p-type conductivity can be continuously adjusted within the range of 1000 - 5000 S / cm. Using a metal copper or copper nitride thin film grown on any substrate at room temperature as the initial precursor material, and then using iodine and sulfur elemental substances as reaction materials for iodine sulfidation synthesis preparation respectively, the detailed implementation manners are as follows:

[0021] Embodiment 1

[0022] (a) Clean the quartz glass substrate and put it into the magnetron sputtering deposition chamber. After the vacuum is pumped to 1×10 -4 Pa, introduce Ar gas until the pressure in the deposition chamber rises to 2 Pa. Then use a metal copper target for DC sputtering, with a power of 30 W and a sputtering time of 2 min, to obtain a metal copper thin film sample with a thickness of about 30 nm.

[0023] (b) Take out the metal copper thin film sample obtained in step (a) from the magnetron sputtering deposition chamber, and place it together with 20 g of sulfur particles with a purity of 99.9% in a quartz glass bottle with a height of 5 cm and a diameter of 3 cm. Heat it to 200 °C and keep it for 10 min. After cooling, obtain a Cu 2-x S amorphous thin film.

[0024] (c) Take out the Cu 2-x S thin film sample obtained in step (b), and place it together with 5 g of iodine particles with a purity of 99.9% in a quartz glass bottle with a height of 5 cm and a diameter of 3 cm. Keep it at room temperature for 10 min to obtain a CuI x S y amorphous thin film.

[0025] (d) The CuI x S yIn the amorphous thin film, x / y = 0.23, and the visible light transmittance is approximately 70% at a wavelength of 550 nm. See Figure 1 ; the conductivity is approximately 1000 S / cm. See Figure 2 , and the sheet resistance corresponding to a film thickness of 100 nm is approximately 100 Ω / sq.

[0026] Example 2

[0027] (a) After cleaning the quartz glass substrate, it is placed in a magnetron sputtering deposition chamber. After the vacuum is pumped to 1×10 -4 Pa, N 2 gas is introduced until the pressure in the deposition chamber rises to 2 Pa. Subsequently, reactive sputtering is carried out using a metallic copper target with a power of 30 W and a sputtering time of 3 min to obtain a copper nitride thin film sample with a thickness of approximately 30 nm.

[0028] (b) The copper nitride thin film sample obtained in step (a) is taken out of the magnetron sputtering deposition chamber and placed together with 5 g of iodine particles with a purity of 99.9% in a quartz glass bottle with a height of 5 cm and a diameter of 3 cm, and kept at room temperature for 20 min to obtain a CuI polycrystalline thin film with a thickness of approximately 100 nm.

[0029] (c) The CuI thin film sample obtained in step (b) is taken out and placed together with 20 g of sulfur particles with a purity of 99.9% in a quartz glass bottle with a height of 5 cm and a diameter of 3 cm, heated to 200 °C, kept for 5 min, and after cooling, a CuI x S y amorphous thin film is obtained.

[0030] (d) In the CuI x S y amorphous thin film prepared in this way, x / y = 0.17. Since the precursor is a copper nitride thin film that is flatter than metallic copper, the visible light transmittance is improved to a certain extent, approximately 73% at a wavelength of 550 nm. See Figure 1 ; the conductivity is approximately 2300 S / cm. See Figure 2 ; the sheet resistance corresponding to a film thickness of 100 nm is approximately 45 Ω / sq.

[0031] Example 3

[0032] The difference between this example and specific example 1 is that the iodination time in step (c) is reduced from 10 min to 2 min, and the others are the same as specific example 1.

[0033] In the CuI x S y amorphous thin film prepared in this way, x / y = 0.05, and the visible light transmittance is approximately 70% at a wavelength of 550 nm. See Figure 1; The conductivity is approximately 4600 S / cm, see Figure 2 ; The sheet resistance corresponding to a film thickness of 100 nm is approximately 22 Ω / sq.

[0034] The above-described embodiments are only several verification examples of the present invention and should not be construed as limiting the scope of the present invention. Several adjustments and improvements made without departing from the concept of the present invention fall within the protection scope of the present invention.

Claims

1. A highly conductive p-type amorphous transparent conductive thin film material, characterized in that, The composition of the thin film material is cuprous iodide sulfide, and its molecular formula is CuI x S y , where 0 < x / y < 0.25; when the visible light transmittance of the thin film material is guaranteed to be > 70%, the hole carrier concentration > 10 22 cm -3 , and the p-type conductivity can be continuously adjusted in the range of 1000 - 5000 S / cm.

2. A preparation method of the highly conductive p-type amorphous transparent conductive thin film material according to claim 1, characterized in that, using a metal copper or copper nitride thin film grown on any substrate at room temperature as an initial precursor material, and then performing iodosulfuration synthesis using iodine and sulfur elements as reaction materials; specifically including: Step 1: Preparation of the precursor material Using a conventional thermal evaporation or magnetron sputtering method, a metal copper or copper nitride thin film is prepared on any substrate at room temperature to obtain a precursor material with a film thickness of 20 - 100 nm; Step 2: Iodosulfuration of the precursor material First, place the precursor material together with sulfur particles weighing 5 - 20 g in a closed glassware, heat it to 150 - 250 °C, hold for 2 - 20 min, and after cooling, obtain a Cu 2-x S amorphous thin film with a thickness of 50 - 300 nm, where 0 < x < 1; Subsequently, place this amorphous thin film Cu 2-x S together with iodine particles weighing 5 - 20 g in a closed glassware, and hold for 2 - 20 min at room temperature to obtain CuI x S y The amorphous thin film is the high-conductivity p-type amorphous transparent conductive thin film material.

3. A preparation method of the highly conductive p-type amorphous transparent conductive thin film material according to claim 1, characterized in that, using a metal copper or copper nitride thin film grown on any substrate at room temperature as an initial precursor material, and then performing iodosulfuration synthesis using iodine and sulfur elements as reaction materials, specifically including: Step 1: Preparation of the precursor material Using a conventional thermal evaporation or magnetron sputtering method, a metal copper or copper nitride thin film is prepared on any substrate at room temperature to obtain a precursor material with a film thickness of 20 - 100 nm; Step 2: Iodosulfuration of the precursor material, First, place the precursor material together with iodine particles weighing 5 - 20 g in a sealed glassware, and keep it at room temperature for 2 - 20 min to obtain a CuI polycrystalline thin film with a thickness of 50 - 300 nm. Subsequently, place this CuI polycrystalline thin film together with sulfur particles weighing 5 - 20 g in a sealed glassware, heat it to 150 - 200 °C, keep it for 2 - 20 min, and after cooling, obtain CuI x S y The amorphous thin film is the high-conductivity p-type amorphous transparent conductive thin film material.

4. According to the preparation method described in claim 2 or 3, characterized in that, The iodine-sulfurization process of the precursor material realizes CuI by adjusting the iodine-sulfurization time. x S y The control of the iodine and sulfur component ratios in the amorphous thin film makes the iodine-sulfur molar ratio satisfy 0 < x / y < 0.25.

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