Preparation method of copper-zinc tin nitride Schottky junction

Abstract

The invention discloses a copper-zinc-tin nitride Schottky junction and a preparation method thereof, and the method comprises the steps: depositing a zinc-tin alloy target in which the ratio of Zn to Sn is 5: 1 on a substrate through a radio frequency sputtering method in a flowing nitrogen and argon atmosphere, and obtaining a zinc-tin nitride film. And annealing the zinc-tin nitride thin film in a flowing argon atmosphere at the temperature of 300-400 DEG C to obtain the annealed zinc-tin nitride thin film. And depositing a copper target on the annealed zinc tin nitride film through a direct current sputtering method in a flowing argon atmosphere to obtain the copper-zinc tin nitride Schottky junction. The problem that a copper-zinc tin nitride Schottky junction prepared by an existing method is poor in rectification effect and has no photovoltaic effect is solved.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor thin film materials, and in particular to a method for preparing a copper-zinc tin nitride Schottky junction. Background Art

[0002] Zinc tin nitride (ZnSnN 2 As an emerging ternary semiconductor material, ZnSn thin film is regarded as an ideal absorber layer for the next generation of solar cells due to its advantages such as abundant resources, non-toxicity, low cost, high absorption coefficient and adjustable energy band (1.0-2.0eV). However, despite the superior performance of ZnSn nitride thin film, its research is not as in-depth as other Zn-IV-N2 materials. This is mainly attributed to its intrinsic defect Sn occupying the position of Zn (Sn Zn ) and the formation energy of the donor generated is extremely low, and the carrier concentration is simplified, which will weaken its key semiconductor properties. In addition, carrier mobility is another important factor affecting the photoelectric conversion efficiency of solar cells, but the mobility of zinc tin nitride films is generally low. At the same time, copper is a metal with excellent electrical conductivity, low price and abundant resource reserves. It is very valuable to study the photovoltaic effect by forming a Schottky junction with copper and zinc tin nitride. However, it is difficult to combine the two, and no photovoltaic effect has been found so far, and the rectification effect of the Schottky junction is poor. Moreover, there is no report on copper-zinc tin nitride Schottky junction and its solar cell.

[0003] Therefore, there is an urgent need for a simple and effective method to prepare a copper-zinc-tin nitride Schottky junction with good rectification and photovoltaic effects to enhance its application value in photovoltaics. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method for preparing a copper-zinc-tin nitride Schottky junction with good rectifying effect and photovoltaic effect, aiming to solve the problem that the copper-zinc-tin nitride Schottky junction prepared by the existing method has poor rectifying effect and cannot produce photovoltaic effect.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a copper-zinc tin nitride Schottky junction, comprising the steps of:

[0007] In a nitrogen and argon atmosphere, a zinc-tin alloy target is deposited on a substrate by radio frequency sputtering to obtain a zinc-tin nitride film.

[0008] The zinc tin nitride film is annealed in an argon atmosphere to obtain an annealed zinc tin nitride film.

[0009] In an argon atmosphere, metallic copper is deposited on the annealed zinc tin nitride film by direct current sputtering to obtain a copper-zinc tin nitride Schottky junction.

[0010] The method for preparing the copper-zinc tin nitride Schottky junction comprises the following steps:

[0011] First, fix the zinc-tin alloy target on the RF target position, evacuate the sputtering system, and then continuously introduce nitrogen and argon while keeping the gas pressure stable. Then, zinc and tin are simultaneously deposited on a silicon wafer or glass substrate or ITO glass by RF sputtering to obtain a zinc-tin nitride film.

[0012] First, the zinc tin nitride film is placed in the sputtering system, the vacuum chamber is evacuated, and then argon gas is continuously introduced while the gas pressure is kept stable. The vacuum chamber is heated to a specified temperature and the temperature is kept constant for a period of time to obtain an annealed zinc tin nitride film.

[0013] First, the annealed zinc tin nitride film is placed in the sputtering system, the copper metal target is fixed on the DC target position, the vacuum chamber is evacuated, and then argon gas is continuously introduced and the gas pressure is kept stable. Then, copper is deposited on the annealed zinc tin nitride film by DC sputtering to obtain a copper-zinc tin nitride Schottky junction.

[0014] In the method for preparing the zinc tin nitride film, the nitrogen is 99.999% high-purity nitrogen, and the argon is 99.995% high-purity argon.

[0015] The method for preparing the zinc tin nitride thin film, wherein the flow rate of the nitrogen gas is 5 sccm, and the flow rate of the argon gas is 8 sccm.

[0016] The method for preparing the zinc tin nitride film, wherein the radio frequency sputtering power is 30W.

[0017] The method for preparing the zinc tin nitride film, wherein the gas pressure of the radio frequency sputtering is 3Pa.

[0018] In the method for preparing the zinc tin nitride thin film, the substrate needs to be cleaned in advance.

[0019] In the method for preparing the zinc tin nitride film, the substrate needs to be cleaned in advance with acetone, alcohol and deionized water.

[0020] In the method for preparing the zinc tin nitride thin film, the substrate needs to be heated to 50-150° C. before thin film deposition.

[0021] In the annealing method of zinc tin nitride film, the argon gas is 99.995% high-purity argon gas.

[0022] In the annealing method of the zinc tin nitride film, the flow rate of the argon gas is 30 sccm.

[0023] The annealing method of the zinc tin nitride film, wherein the gas pressure during the annealing is 1Pa.

[0024] The annealing method of the zinc tin nitride film, wherein the zinc tin nitride film needs to be heated to 300-400° C. before annealing.

[0025] The method for preparing the copper-zinc tin nitride Schottky junction, wherein the argon gas is 99.995% high-purity argon gas.

[0026] The method for preparing the copper-zinc tin nitride Schottky junction, wherein the flow rate of the argon gas is 30 sccm.

[0027] The method for preparing the copper-zinc tin nitride Schottky junction, wherein the gas pressure of the direct current sputtering is 2Pa.

[0028] A copper-zinc-tin nitride Schottky junction, characterized in that it is prepared by the method described above.

[0029] Beneficial effects: The present invention deposits the alloy target on the substrate by radio frequency sputtering in a flowing nitrogen and argon atmosphere, and then anneals it to form a Schottky junction with copper, thereby solving the problem of poor rectification effect and discovering that a photovoltaic effect occurs therein. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 X-ray diffraction pattern of the sample prepared by the present invention;

[0031] Figure 2 X-ray electron energy scattering spectrum of the sample prepared by the present invention;

[0032] Figure 3 This is a dark-state IV test diagram of the sample prepared by the present invention.

[0033] Figure 4 This is a test diagram of the illumination state IV of the sample prepared in the present invention. DETAILED DESCRIPTION

[0034] The present invention provides a method for preparing a copper-zinc tin nitride Schottky junction. In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] The method for preparing the copper-zinc tin nitride Schottky junction of the present invention comprises the steps of:

[0036] In a flowing nitrogen and argon atmosphere, a zinc-tin alloy target is deposited on a substrate by radio frequency sputtering to obtain a zinc-tin nitride film.

[0037] Different from the conventional method of preparing zinc tin nitride thin film by co-sputtering metal zinc by radio frequency sputtering and metal tin by direct current sputtering, the present invention uses flowing nitrogen as a reaction gas and flowing argon as bombarding particles to perform radio frequency sputtering on a zinc-tin alloy target and deposit the target on a substrate, thereby preparing a zinc tin nitride thin film with a low carrier concentration.

[0038] In the method for preparing the zinc-tin nitride thin film of the present invention, the zinc-tin alloy target is first fixed on the radio frequency target position, and then the entire sputtering system is evacuated to a vacuum degree of 4.5×10 -4 Pa to ensure that there is no impurity gas such as oxygen, and then continuously introduce nitrogen and argon to keep the gas pressure stable, that is, introduce nitrogen and argon while discharging them at a certain rate to ensure that the entire magnetron sputtering system remains in a certain gas pressure environment, and then use radio frequency sputtering to simultaneously deposit zinc and tin on a silicon wafer or a glass substrate to obtain a zinc tin nitride film.

[0039] Preferably, the substrate needs to be cleaned in advance, for example, by cleaning with acetone, alcohol and deionized water in an ultrasonic environment to remove oil stains, impurities and the like on the surface of the substrate, so as to facilitate thin film deposition, and then the substrate is dried for standby use. The substrate can be single crystal silicon, indium tin oxide (ITO) glass, or a cheap silicon wafer or glass such as Si (100) or K9 glass, all of which can be used to prepare zinc tin nitride thin films in the present invention.

[0040] Preferably, in the present invention, before thin film deposition, the substrate is preheated and maintained at 50-150° C., because impurities are likely to appear if the temperature is too high, and the thin film is likely to become amorphous if the temperature is too low.

[0041] Before depositing the film, the alloy target can be pre-sputtered for a period of time (e.g., 5 minutes) to remove oxides and impurities on the target surface to avoid depositing these oxides or impurities on the substrate, which will eventually lead to contamination or even failure of the zinc tin nitride film.

[0042] The zinc-tin alloy target is a zinc-tin alloy target with a ratio of Zn:Sn=5:1. The power of radio frequency sputtering on the zinc-tin alloy target is 30W, so that the target is deposited on the substrate to form a zinc-tin nitride film.

[0043] In the method for preparing the zinc tin nitride film, the nitrogen is 99.999% high-purity nitrogen and the argon is 99.995% high-purity argon to avoid interference of impurity gases on the sputtering reaction as much as possible, thereby improving the quality of the zinc tin nitride film.

[0044] Preferably, the flow rate of the nitrogen gas is 5 sccm, and the flow rate of the argon gas is 8 sccm. The zinc tin nitride film prepared under the flowing nitrogen and argon gas with the above flow rates has a low carrier concentration and a high mobility, and is of particularly good quality.

[0045] In a flowing argon atmosphere, at a constant temperature and pressure, the zinc tin nitride film is placed in a sputtering system for a period of time to obtain an annealed zinc tin nitride film.

[0046] Different from the conventional annealing method under high vacuum, in the present invention, argon gas with a certain flow rate is used to maintain a stable gas pressure, so that an annealed zinc tin nitride film with low carrier concentration and good crystallinity can be prepared.

[0047] In the annealing method of the zinc tin nitride film of the present invention, the zinc tin nitride film is first placed in a sputtering system, and then the entire sputtering system is evacuated to a vacuum degree of 4.5×10 -4 Pa to ensure that there is no impurity gas such as oxygen, and at the same time control the temperature to remain constant, and then continue to introduce argon and keep the pressure stable, that is, while introducing argon, it is discharged at a certain rate to ensure that the entire vacuum chamber remains in a certain pressure environment, and then maintained for a period of time to obtain the annealed zinc tin nitride film.

[0048] Preferably, the zinc tin nitride film needs to be prepared in advance, for example, the zinc tin nitride film used for this annealing is the zinc tin nitride film prepared above. Zinc tin nitride films prepared under other conditions can also be used to prepare the annealed zinc tin nitride film in the present invention.

[0049] Preferably, in the present invention, before the thin film annealing is performed, the substrate is preheated and maintained at 300-400° C., and the thin film is annealed at a constant temperature of 300-400° C.

[0050] In the annealing method of the zinc tin nitride film, the argon gas is 99.995% high-purity argon gas to avoid interference of impurity gases on annealing as much as possible, thereby improving the quality of the annealed zinc tin nitride film, and at the same time ensuring that the gas pressure of the entire system is stable at 1Pa, that is, even if the annealing gas pressure is 1Pa, under this gas pressure intensity, the film can have better crystallinity, better film density, and obtain lower carrier concentration and better carrier mobility.

[0051] Preferably, the flow rate of the argon gas is 30 sccm. The zinc tin nitride film annealed under the flowing argon gas with the above flow rate has a low carrier concentration and a high mobility, and the quality is particularly good.

[0052] In a flowing argon atmosphere and at a fixed pressure, a copper target is deposited on the annealed zinc tin nitride film by a DC sputtering method to obtain a copper-zinc tin nitride Schottky junction.

[0053] In the present invention, argon gas with a certain flow rate is used to maintain a stable gas pressure and is used as bombardment particles to perform direct current sputtering on a copper target, thereby preparing a copper-zinc tin nitride Schottky junction with good rectification effect and photovoltaic effect.

[0054] In the method for preparing the copper-zinc tin nitride Schottky junction of the present invention, the copper target is first fixed on the DC target position, and then the entire sputtering system is evacuated to a vacuum degree of 4.5×10 -4 Pa to ensure that there is no impurity gas such as oxygen, and then continue to introduce argon and keep the gas pressure stable, that is, while introducing argon, it is discharged at a certain rate to ensure that the entire vacuum chamber is maintained at a certain gas pressure environment, and then copper is deposited on the annealed zinc tin nitride film by DC sputtering to obtain a copper-zinc tin nitride Schottky junction.

[0055] Preferably, the annealed zinc tin nitride film needs to be prepared in advance, for example, the zinc tin nitride film used for this annealing is the annealed zinc tin nitride film prepared above. Annealed zinc tin nitride films prepared under other conditions can also be used in the present invention to prepare copper-zinc tin nitride Schottky junctions.

[0056] In the preparation method of the copper-zinc-tin nitride Schottky junction, the argon gas is 99.995% high-purity argon gas to avoid interference of impurity gases on annealing as much as possible, thereby improving the quality of the copper-zinc-tin nitride Schottky junction and ensuring that the gas pressure of the entire system is stable at 2Pa. Even if the sputtering gas pressure is 2Pa, the copper as an electrode can be better combined with the zinc-tin nitride film, and the thickness of the copper can be more uniform.

[0057] Preferably, the flow rate of the argon gas is 30 sccm. The zinc tin nitride film annealed under the flowing argon gas with the above flow rate has a low carrier concentration and a high mobility, and the quality is particularly good.

[0058] The present invention also provides a copper-zinc tin nitride Schottky junction, which is prepared by the method described above.

[0059] The present invention is described in detail below by way of examples.

[0060] Example 1

[0061] Si (100) and K9 glass were used as substrates, and the substrates were ultrasonically cleaned with acetone, alcohol and deionized water in turn. A zinc target with a Zn:Sn = 5:1 alloy target was fixed on the RF target position. Then the background vacuum of the sputtering system was evacuated to 4.5×10 -4Pa, high-purity nitrogen with a flow rate of 5sccm and high-purity argon with a flow rate of 8sccm are introduced, and the target is pre-sputtered for 5min to remove oxides and impurities on the target surface, and then the substrate is heated to a temperature of 100°C, and then the zinc-tin alloy target is radio-frequency sputtered at a sputtering power of 30W at a working pressure of 3Pa for 60 minutes to obtain a zinc-tin nitride film. After the sputtering coating is completed, the sputtering source and the air inlet valve are turned off, and when the substrate temperature drops to room temperature, the vacuum pump, power supply and other switches are turned off in sequence, and the sample is taken out.

[0062] The samples were subjected to X-ray diffraction (XRD) test, and the results were as follows: Figure 1 As shown, from Figure 1 It can be seen that under the preparation conditions adopted in the present invention, the prepared film is in a microcrystalline state.

[0063] The samples were tested by EDS, and the results were as follows: Figure 2 As shown, from Figure 2 It can be seen that the film is not disturbed by other gas elements and its main elements are zinc, tin and nitrogen.

[0064] Place the sample in the sputtering system and evacuate the sputtering system to a vacuum of 4.5 × 10 -4 Pa, high-purity argon gas with a flow rate of 30sccm is introduced, and then the substrate is heated to a temperature of 350°C, and then maintained at a working pressure of 1Pa for 60 minutes to obtain an annealed zinc tin nitride film. After the zinc tin nitride annealing is completed, the air inlet valve is closed, and when the substrate temperature drops to room temperature, the vacuum pump, power supply and other switches are turned off in sequence, and the sample is taken out.

[0065] The annealed sample was placed in the sputtering system; a copper target with a purity of 99.999% was fixed on the DC target position; and the background vacuum of the sputtering system was evacuated to 4.5×10 -4 Pa, high-purity argon gas with a flow rate of 30sccm was introduced, and the target was pre-sputtered for 5 minutes to remove oxides and impurities on the target surface, and then the copper target was radio frequency sputtered at a sputtering power of 10W at a working pressure of 2Pa for 20 minutes to obtain a copper-zinc nitride tin Schottky junction. After the sputtering coating was completed, the sputtering source and the air inlet valve were turned off, and when the substrate temperature dropped to room temperature, the vacuum pump, power supply and other switches were turned off in turn, and the sample was taken out.

[0066] The samples were tested in dark and light conditions. Figure 3 and Figure 4 As shown. Figure 3 It can be seen that the rectification effect of copper-zinc tin nitride Schottky junction is better. Figure 4 Show its photovoltaic effect.

[0067] From the above implementation, it can be seen that the zinc tin nitride film is sputtered at 100°C, annealed at 350°C and combined with copper to form a Schottky junction, which can effectively improve the problem of poor rectification effect and produce a photovoltaic effect.

[0068] In summary, the present invention provides a copper-zinc-tin nitride Schottky junction and a preparation method thereof, wherein a zinc-tin alloy target with a ratio of Zn:Sn=5:1 is deposited on a substrate by radio frequency sputtering in a flowing nitrogen and argon atmosphere, thereby preparing a zinc-tin nitride film with low carrier concentration and high mobility. After annealing, the copper target is sputtered on the zinc-tin nitride film by direct current sputtering to form a Schottky junction, thereby solving the problem that the copper-zinc-tin nitride Schottky junction has poor rectification effect and no photovoltaic effect.

[0069] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a copper-zinc tin nitride Schottky junction, characterized in that: Includes steps: In a flowing nitrogen and argon atmosphere, a zinc-tin alloy target with a ratio of Zn:Sn=5:1 is deposited on a substrate by radio frequency sputtering to obtain a zinc-tin nitride film. In a flowing argon atmosphere, the zinc-tin nitride film is annealed at a certain temperature. In a flowing argon atmosphere, a copper target is deposited on the zinc-tin nitride film by direct current sputtering to obtain a copper-zinc-tin nitride Schottky junction.

2. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 1, characterized in that: Includes steps: First, fix the alloy target of Zn:Sn=5:1 on the RF target position, evacuate the sputtering system, and then continuously introduce nitrogen and argon to keep the gas pressure stable. Then, zinc and tin are simultaneously deposited on the silicon wafer or glass substrate by RF sputtering to obtain a zinc-tin nitride film. Put the zinc-tin nitride film into the sputtering system, evacuate the sputtering system, and then continuously introduce argon to keep the gas pressure stable. Then, copper is deposited on the zinc-tin nitride film by DC sputtering to obtain a copper-zinc-tin nitride Schottky junction.

3. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 2, characterized in that: The nitrogen is 99.999% high-purity nitrogen, and the argon is 99.995% high-purity argon.

4. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 3, characterized in that: The flow rate of the nitrogen gas is 5 sccm, the flow rate of the argon gas for preparing the zinc tin nitride film is 8 sccm, the flow rate of the argon gas for annealing the zinc tin nitride film is 30 sccm, and the flow rate of the argon gas for preparing the copper-zinc tin nitride Schottky junction is 30 sccm.

5. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 1, characterized in that: The RF sputtering power is 30W, and the DC sputtering power is 10W.

6. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 1, characterized in that: The gas pressure for preparing the zinc tin nitride film is 3Pa, the gas pressure for annealing the zinc tin nitride film is 1Pa, and the gas pressure for preparing the copper-zinc tin nitride Schottky junction is 2Pa.

7. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 1, characterized in that: The substrate needs to be cleaned in advance.

8. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 1, characterized in that: The substrate needs to be cleaned with acetone, alcohol and deionized water in advance.

9. The method for preparing a copper-zinc tin nitride Schottky junction according to claim 1, characterized in that: The substrate needs to be heated to 50-150° C. before the zinc tin nitride film is deposited, and the zinc tin nitride film needs to be heated to 300-400° C. before annealing.

10. A copper-zinc-tin nitride Schottky junction, characterized in that: The method is prepared by any one of claims 1 to 9.

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