Zr / NbMoTaWO multilayer film with multi-band gap combination and preparation method of Zr / NbMoTaWO multilayer film
By preparing Zr/NbMoTaWO multilayer film, combined with the change of oxygen content gradient, a multi-bandgap combination is achieved, solving the problem of constant bandgap of a single transition metal oxide, improving the light absorption and response capabilities of optoelectronic devices, and is suitable for ultra-efficient stacked solar cells, wide-spectrum photodetectors and multi-color imaging sensors.
Patent Information
- Application Number
- CN202510521267.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-24
- Publication Date
- 2025-07-25
AI Technical Summary
The band gap of existing single transition metal oxides is constant, which makes it only correspond to one fixed wavelength in optoelectronic applications, and cannot achieve the absorption of the entire solar spectrum, limiting its application in the wide spectrum field.
Zr/NbMoTaWO multilayer film was prepared by magnetron sputtering method. The alternating structure of Zr oxide and NbMoTaW oxide was adopted, and combined with the change of oxygen content gradient, a multilayer film with double direct band gap and double indirect band gap was formed to achieve ultraviolet-visible-near-infrared full spectrum response.
It achieves high-efficiency light absorption and wide spectrum response, improving the performance of optoelectronic devices, especially in applications such as ultra-efficiency stacked solar cells, wide-spectrum photodetectors and multi-color imaging sensors.
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Figure CN120366715A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a Zr / NbMoTaWO multilayer film with a multi-bandgap combination and a preparation method thereof, belonging to the technical field of semiconductor materials. Background Art
[0002] High entropy is not only an effective way to integrate the characteristics of multiple components, but also can obtain good high-temperature stability due to the configurational entropy increase effect. When preparing high-entropy oxide films, the film composition can be further regulated by changing the oxygen flow rate. Therefore, preparing high-entropy oxide films can not only optimize and combine the intrinsic properties of single metal oxides, but also expand the performance range through the interaction between multiple components, such as achieving a wide-spectrum tunable optical response, multi-band optoelectronic regulation ability, etc.
[0003] When the composition and structure of a single transition metal oxide are determined, the bandgap will be constant at a single value. NbO2 has an indirect bandgap of 0.3 eV and is usually applied in the fields of near-infrared light detection and photothermal conversion due to its narrow bandgap characteristics. MoO3 has a direct bandgap of 1.4 eV, and WO3 has a direct bandgap of 1.5 eV. Due to their moderate bandgap characteristics, they show extensive applications in the fields of visible light absorption and photoelectrocatalysis. Ta2O5 has a relatively wide direct bandgap of 2.9 eV and is usually applied in the fields of ultraviolet light detection, high-dielectric materials, and photocatalytic water splitting, etc. Monoclinic ZrO2 has a relatively wide direct bandgap (3.4 eV) and is mostly applied in the fields of ultraviolet optoelectronic devices and photocatalytic applications. The indirect bandgap of tetragonal ZrO2 is 3.5 eV, and with its wider indirect bandgap, it shows important application value in the fields of high-temperature dielectric materials and transparent insulating coatings, etc. In addition, the oxygen-deficient zirconia (ZrO 2-x formed by introducing oxygen vacancies in ZrO2) has its bandgap significantly reduced from 5.09 eV to 1.52 eV. This narrow bandgap characteristic extends its light response range to the visible light and even the near-infrared region, greatly improving the solar energy utilization efficiency. Obviously, after the bandgap of a single-component material is constant, it can only correspond to a fixed wavelength and cannot achieve full solar spectrum absorption, which has significant limitations in optoelectronic applications. For example, the narrow indirect bandgap of NbO2 is suitable for near-infrared detection, but severely limits its application in the wide-spectrum field; while the bandgap values of MoO3 and WO3 are moderate, making their applications in the visible light range have significant advantages, but at the same time, they limit their applications in the ultraviolet and near-infrared bands. Summary of the Invention
[0004] To solve the problems existing in the prior art, the present invention provides a Zr / NbMoTaWO multi-layer film with a multi-bandgap combination and a preparation method thereof. The multi-layer film with a multi-bandgap combination is prepared on a (100)-oriented single-crystal Si substrate and a (0001)-oriented single-crystal Al2O3 substrate by magnetron sputtering technology. The Zr / NbMoTaWO multi-layer film combines the properties of various transition metal oxides and constructs a layer with a gradient change in oxygen content in the film. This unique structure not only realizes the precise integration of direct and indirect bandgaps, covering the full-spectrum response of ultraviolet-visible-near-infrared, but also optimizes the carrier dynamics characteristics through the controllable oxygen vacancy distribution.
[0005] The technical solution of the present invention is: a Zr / NbMoTaWO multi-layer film with a multi-bandgap combination, characterized in that: the multi-layer film is an alternating structure of Zr oxide and NbMoTaW oxide, the Zr / O atomic ratio of the Zr oxide layer is 21.5 / 59.4, and the NbMoTaW / O atomic ratio of the NbMoTaW oxide layer is 38.3 / 61.1, having double direct bandgaps and double indirect bandgaps, and the direct bandgaps are E dir-g1 = 2.4 eV and E dir-g2 = 4.0 eV respectively, and the indirect bandgaps are E indir-g1 = 0.6 eV and E indir-g2 = 3.8 eV respectively. The multi-layer film can be applied to fields such as ultra-high-efficiency tandem solar cells, broadband photodetectors, and multi-color imaging sensors.
[0006] A preparation method of a Zr / NbMoTaWO multi-layer film with a multi-bandgap combination includes the following steps:
[0007] S1. Sputtering targets: including a pure Zr target and a NbMoTaW equimolar ratio quaternary high-entropy alloy target, and the metal purity of the targets is not less than 99.9 wt.%.
[0008] S2. Cleaning the substrate;
[0009] S3. Magnetron sputtering to prepare the film: Put the cleaned substrate into the vacuum chamber and start sputtering when the background vacuum degree is higher than 3×10 -4 Pa.
[0010] S3.1. Preparation of the Zr oxide layer: Use a 50 W unbiassed DC power supply, an argon flow rate of 30 sccm, and an official sputtering time of 1 min;
[0011] S3.2. Preparation of the NbMoTaW oxide layer: Use a 100 W unbiassed RF power supply, and use a mixed gas of 29.1 sccm argon and 0.9 sccm oxygen for an official sputtering time of 2 min;
[0012] One layer of Zr oxide layer and one layer of NbMoTaW oxide layer form a cycle, and 10 cycles are continuously deposited according to the above method; after sputtering is completed, the thin film sample can be taken out after the equipment is cooled to room temperature.
[0013] Further, in the step S2, the substrate is a (100)-oriented single-crystal Si substrate or a (0001)-oriented single-crystal Al2O3 substrate.
[0014] Further, cleaning of the (100)-oriented single-crystal Si substrate: The substrate is ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water for 10 min in sequence, taken out and immersed in 5% hydrofluoric acid for 2 - 3 minutes to remove SiO2 on the surface of single-crystalline silicon, and finally the residual acid on the surface is rinsed clean with deionized water; after cleaning, it is dried with N2;
[0015] Cleaning of the (0001)-oriented single-crystal Al2O3 substrate: The substrate is ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water in sequence, and after cleaning, it is dried with N2.
[0016] Specifically, the preparation method of the Zr / NbMoTaWO multi-layer film with a multi-bandgap combination adopts the following steps:
[0017] (1) Sputtering targets: including a pure Zr target and a NbMoTaW (equimolar ratio) quaternary high-entropy alloy target, and the metal purity of the targets is not less than 99.9 wt.%.
[0018] (2) Cleaning the substrate: The substrates required for thin film growth include a (100)-oriented single-crystal Si substrate and a (0001)-oriented single-crystal Al2O3 substrate. The single-crystalline silicon substrate is ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water for 10 min in sequence, taken out and immersed in 5% hydrofluoric acid for 2 - 3 minutes to remove SiO2 on the surface of single-crystalline silicon, and finally the residual acid on the surface is rinsed clean with deionized water; after cleaning, it is dried with N2 and put into the vacuum chamber; the single-crystalline Al2O3 substrate needs to be ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water for 10 min in sequence, and after cleaning, it is dried with N2 and put into the vacuum chamber;
[0019] (3) Magnetron sputtering to prepare the thin film: When the background vacuum degree is higher than 3×10 -4 Pa, the Zr / NbMoTaW dual-target alternating sputtering starts. The Zr layer uses a 50W unbiassed DC power supply, the argon gas flow rate is 30 sccm, and the formal sputtering time is 1 min; the NbMoTaWO layer uses a 100W unbiassed RF power supply, and a mixed gas of 29.1 sccm argon gas and 0.9 sccm oxygen gas is used for the formal sputtering time of 2 min. One layer of Zr layer and one layer of NbMoTaWO layer form a cycle, and 10 cycles are continuously deposited according to the above method. After sputtering is completed, the thin film sample can be taken out after the equipment is cooled to room temperature.
[0020] Zr / NbMoTaWO nanomultilayer film, by utilizing the strong binding effect between Zr and O, enables oxygen to spontaneously diffuse from the NbMoTaWO layer to the Zr layer, naturally forming a ZrO layer with a changing oxygen concentration gradient, achieving a combination of multiple oxides with different bandgaps. It can also bring about a natural change in oxygen content, introduce factors for changing the bandgap from multiple angles, and realize the composition of a multi-bandgap thin film. The ZrO2 formed by the oxidation of Zr has diverse bandgap widths, and different structures of ZrO2 have different direct and indirect bandgaps. The multilayer film in this application has double direct bandgaps and double indirect bandgaps, with the direct bandgaps being E x = 2.4 eV and E dir-g1 = 4.0 eV respectively, and the indirect bandgaps being E dir-g2 = 0.6 eV and E indir-g1 = 3.8 eV respectively. This multilayer film can be applied in fields such as ultra-high-efficiency tandem solar cells, broadband photodetectors, and multicolor imaging sensors. indir-g2 = 3.8 eV. This multilayer film can be applied in fields such as ultra-high-efficiency tandem solar cells, broadband photodetectors, and multicolor imaging sensors.
[0021] The beneficial effects of the present invention are as follows: The Zr / NbMoTaWO multilayer film is prepared by magnetron sputtering. The film has high purity, clear interfaces between the multilayers, and uniform thickness. It has a combination of double direct and double indirect bandgaps, and has both high-efficiency light absorption and ultraviolet-visible-infrared multi-band broadband spectral response, significantly improving the performance of optoelectronic devices. The direct bandgap enables high-efficiency light absorption and radiative recombination at specific wavelengths, improving the quantum efficiency of devices such as solar cells and photodetectors. The indirect bandgap extends the long-wave response and prolongs the carrier lifetime. This material system combines the stability of high-entropy materials and the flexibility of multilayer energy band engineering, providing a new way to break through the performance bottleneck for the next generation of optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 is the (αE) 2 -E relationship curve of the Zr / NbMoTaWO multilayer film. (a) Narrow bandgap band (b) Wide bandgap band.
[0023] Figure 2 is the (αE) 1 / 2 -E relationship curve of the Zr / NbMoTaWO multilayer film. (a) Narrow bandgap band (b) Wide bandgap band. DETAILED DESCRIPTION OF THE INVENTION
[0024] The specific embodiments of the present invention will be described in detail below in combination with the technical solutions.
[0025] Example: Preparation of Zr / NbMoTaWO multilayer film by magnetron sputtering
[0026] (I) Sputtering target:
[0027] Pure Zr target and NbMoTaW (equimolar ratio) quaternary high-entropy alloy target, with the metal purity of the target materials not less than 99.9 wt.%;
[0028] (II) Preparation of Zr / NbMoTaWO multilayer films with multi-bandgap combinations:
[0029] ① Clean the (100)-oriented single-crystalline Si substrate and (0001)-oriented single-crystalline Al2O3 substrate required for film growth: The single-crystalline silicon substrate is ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water for 10 min in sequence. After taking it out, it is immersed in 5% hydrofluoric acid for 2 - 3 minutes to remove SiO2 on the surface of the single-crystalline silicon. Finally, the residual acid on the surface is rinsed clean with deionized water. After cleaning, it is dried with N2 and put into the vacuum chamber; The single-crystalline Al2O3 substrate needs to be ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water for 10 min in sequence. After cleaning, it is dried with N2 and put into the vacuum chamber;
[0030] ② Magnetron sputtering to prepare the film: When the vacuum is pumped to below 3.0×10 -4 Pa, start the alternate sputtering of the Zr / NbMoTaW dual targets. The Zr layer uses a 50W non-biased DC power supply, with an argon flow rate of 30 sccm and a formal sputtering time of 1 min; The NbMoTaWO layer uses a 100W non-biased RF power supply, and a mixed gas of 29.1 sccm argon and 0.9 sccm oxygen is used for a formal sputtering time of 2 min. One Zr layer and one NbMoTaWO layer form a cycle, and 10 cycles are continuously deposited according to the above method. After sputtering, the film sample can be taken out after the equipment is cooled to room temperature.
[0031] (III) Analysis
[0032] Select the film deposited on the (100)-oriented single-crystalline Si substrate for the analysis of the film's microstructure, morphology, and the composition of the multilayer film. Use the JEM2100F transmission electron microscope of JEOL Ltd. and the energy-dispersive spectrometer equipped with it for measurement. The average thickness of the Zr layer is 6.2 nm, the average thickness of the NbMoTaWO layer is 18.4 nm, and the total film thickness is 246 nm. This multilayer film is an alternating structure of Zr oxide and NbMoTaW oxide. The Zr / O atomic ratio in the Zr oxide layer is 21.5 / 59.4, and the NbMoTaW / O atomic ratio in the NbMoTaW oxide layer is 38.3 / 61.1.
[0033] Use a UV3600 type ultraviolet-visible-near-infrared spectrophotometer to measure the bandgap width of the film deposited on the (0001)-oriented single-crystalline Al2O3 substrate. As Figure 1 、 2 shown, Figure 1 in: The abscissa is the energy E, with the unit of eV, and the ordinate is (αE) 2, in the unit of (10 5 cm -1 ·eV) 2 , it can be seen from the figure that the Zr / NbMoTaWO multilayer film prepared by the present invention has two direct band gaps, which are E dir-g1 = 2.4 eV and E dir-g2 = 4.0 eV respectively. Figure 2 In it: the abscissa is the energy E, in the unit of eV, and the ordinate is (αE) 1 / 2 , in the unit of (10 5 cm -1 ·eV) 1 / 2 , it can be seen from the figure that the Zr / NbMoTaWO multilayer film prepared by the present invention has two indirect band gaps, which are E indir-g1 = 0.6 eV and E indir-g2 = 3.8 eV respectively.
[0034] (IV) Applications
[0035] This Zr / NbMoTaWO multilayer film with a multi-bandgap combination has important applications in multiple cutting-edge optoelectronic fields due to its adjustable energy band structure and wide-spectrum response characteristics, such as ultra-high-efficiency tandem solar cells, wide-spectrum photodetectors, multi-color imaging sensors, etc.
[0036] The above-mentioned embodiments are only used to illustrate the present invention. Any equivalent transformation and improvement made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.
Claims
1. A preparation method of a Zr / NbMoTaWO multilayer film with a multi-bandgap combination, characterized in that, It includes the following steps: S1. Sputtering targets: including a pure Zr target and a quaternary high-entropy alloy target of NbMoTaW with an equimolar ratio, and the metal purity of the targets is not less than 99.9 wt.%. S2. Cleaning the substrate; S3. Preparation of thin film by magnetron sputtering: Place the cleaned substrate into the vacuum chamber and start sputtering when the background vacuum degree is higher than 3×10 -4 Pa. S3.
1. Preparation of the Zr oxide layer: Using a 50W non-biased DC power supply, an argon flow rate of 30 sccm, and a formal sputtering time of 1 min; S3.
2. Preparation of the NbMoTaW oxide layer: Using a 100W non-biased RF power supply, using a mixed gas of 29.1 sccm argon and 0.9 sccm oxygen, and a formal sputtering time of 2 min; One layer of Zr oxide layer and one layer of NbMoTaW oxide layer form a cycle, and 10 cycles are continuously deposited according to the above method; after sputtering is completed, the thin film sample can be taken out after the equipment is cooled to room temperature.
2. A method for preparing a Zr / NbMoTaWO multilayer film with a multi-bandgap combination according to claim 1, characterized in that: In the step S2, the substrate is a (100)-oriented single-crystal Si substrate or a (0001)-oriented single-crystal Al2O3 substrate.
3. A method for preparing a Zr / NbMoTaWO multilayer film with a multi-bandgap combination according to claim 2, characterized in that: Cleaning of the (100)-oriented single-crystal Si substrate: The substrate is ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water for 10 min in sequence, taken out and immersed in 5% hydrofluoric acid for 2 - 3 minutes to remove SiO2 on the surface of single-crystalline silicon, and finally the residual acid on the surface is rinsed clean with deionized water; after cleaning, it is dried with N2; Cleaning of the (0001)-oriented single-crystal Al2O3 substrate: The substrate is ultrasonically cleaned in anhydrous ethanol, acetone, and deionized water in sequence, and after cleaning, it is dried with N2.
4. A Zr / NbMoTaWO multilayer film with a multi-bandgap combination, characterized in that: The multilayer film is prepared by using the preparation method described in any one of claims 1 - 3.
5. A Zr / NbMoTaWO multilayer film with a multi-bandgap combination according to claim 4, characterized in that: The multilayer film has an alternating structure of Zr oxide and NbMoTaW oxide, and the Zr / O atomic ratio in the Zr oxide layer is 21.5 / 59.4, and the NbMoTaW / O atomic ratio in the NbMoTaW oxide layer is 38.3 / 61.
1.
6. A Zr / NbMoTaWO multilayer film with a multi-bandgap combination according to claim 4, characterized in that: The multi-layer film has double direct bandgaps and double indirect bandgaps, and the direct bandgaps are E dir-g1 = 2.4 eV, E dir-g2 = 4.0 eV respectively, and the indirect bandgaps are E indir-g1 = 0.6 eV, E indir-g2 = 3.8 eV.
7. Application of the Zr / NbMoTaWO multilayer film with a multi-bandgap combination described in claim 4, and this multilayer film is applied to the fields of stacked solar cells, photodetectors, and imaging sensors.