Method for passivating sulfur vacancy defect in molybdenum disulfide film

Abstract

The invention discloses a method for passivating a sulfur vacancy defect in a molybdenum disulfide film, and belongs to the technical field of semiconductor material preparation. According to the method, the molybdenum foil and the molybdenum disulfide are placed in the argon / oxygen atmosphere together for annealing, and the characteristic that the molybdenum foil is easier to oxidize than the molybdenum disulfide is utilized, so that the reaction of oxygen and the molybdenum disulfide tends to defect passivation (weak reaction) instead of oxidation etching (strong reaction); on the basis, the reaction degree of oxygen and molybdenum disulfide is controlled by adjusting the proportion of oxygen in argon / oxygen, the gas flow, the pressure intensity, the passivation temperature and the passivation time, so that the sulfur vacancy defect is passivated, the high-quality molybdenum disulfide thin film is finally obtained, and further application of the molybdenum disulfide thin film to photoelectric devices is expected to be promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor material preparation, and in particular relates to a method for passivating sulfur vacancy defects in a molybdenum disulfide film. Background Art

[0002] Two-dimensional transition metal dichalcogenides (TMDCs) are a class of layered materials that are connected by covalent bonds within the plane and interact with each other by van der Waals forces. Molybdenum disulfide (MoS2), as one of the earliest TMDCs studied, is considered a hot candidate for the next generation of semiconductor materials due to its unique electrical properties. Therefore, the preparation of MoS2 thin films has important research significance in both basic research and practical applications.

[0003] Studies have shown that sulfur vacancy defects in MoS2 thin films prepared by chemical vapor deposition (CVD) will significantly affect its physical and chemical properties. In terms of optoelectronic properties, sulfur vacancy defects will reduce the proportion of neutral excitons in MoS2 thin films, thereby reducing the photoluminescence efficiency. Therefore, repairing or passivating sulfur vacancy defects is of great significance to promoting the application of MoS2 thin films in the optoelectronic field. Summary of the invention

[0004] The purpose of the present invention is to provide a method for passivating sulfur vacancy defects in molybdenum disulfide films, on this basis obtain high-quality MoS2 films, and further promote their application in optoelectronic devices.

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

[0006] A method for passivating sulfur vacancy defects in a molybdenum disulfide film comprises the following steps:

[0007] (1) Cleaning the quartz boat and substrate: Place the quartz boat, molybdenum foil and growth substrate in acetone ultrasonic bath for 15 min, anhydrous ethanol for 15 min, and deionized water for 15 min, and blow dry with a nitrogen gun.

[0008] (2) Preparation of MoS2 thin film: a) Use an electronic scale to weigh sulfur (S) powder and molybdenum pentachloride (MoCl5) powder, put the weighed S powder and MoCl5 powder into a quartz boat, and send them into two temperature zones of a tube furnace. Put the S powder into the first temperature zone, and put the MoCl5 powder and the growth substrate into the second temperature zone according to the direction of the air flow. The schematic diagram of the device is shown in the figure. Figure 1 As shown; b) under argon 500sccm, the first temperature zone and the second temperature zone are heated to 110°C and kept warm for 10 minutes to remove water vapor; c) under argon atmosphere, the growth chamber is evacuated to the growth pressure, and then the first temperature zone and the second temperature zone are heated to the growth temperature respectively, and then kept warm for the growth time to grow MoS2 film, and finally naturally cooled to room temperature to obtain MoS2 film.

[0009] (3) Sulfur vacancy defect passivation: a) Place the molybdenum foil and the MoS2 film prepared above on the top and bottom of the quartz boat respectively, and then send them into the central temperature zone of the tube furnace. The schematic diagram of the device is shown in Figure 2 As shown; b) introducing an argon / oxygen mixed gas, adjusting the oxygen ratio, flow rate and pressure of the mixed gas, then heating to a certain temperature, keeping it warm for a certain time, and finally naturally cooling it to room temperature to obtain a high-quality MoS2 film after sulfur vacancy passivation.

[0010] Furthermore, in step (2), the mass of S powder is 30-2000 mg.

[0011] Furthermore, in step (2), the mass of MoCl5 powder is 1-50 mg.

[0012] Furthermore, in step (2), the argon gas flow rate is 10-200 sccm.

[0013] Furthermore, in step (2), the growth pressure is 100-10000Pa.

[0014] Furthermore, in step (2), the temperature in the first temperature zone is 150-350°C.

[0015] Furthermore, in step (2), the temperature of the second temperature zone is 750-900°C.

[0016] Furthermore, in step (2), the growth time is 10-30 min.

[0017] Furthermore, in step (3), the proportion of oxygen in the argon / oxygen mixed gas is 0.01%-1%.

[0018] Furthermore, in step (3), the flow rate of the argon / oxygen mixed gas is 10-200 sccm.

[0019] Furthermore, in step (3), the passivation pressure is 100-5000Pa.

[0020] Furthermore, in step (3), the passivation temperature is 300-500°C.

[0021] Furthermore, in step (3), the passivation time is 5-30 min.

[0022] In summary, by adopting the above technical solution, the beneficial effects of the present invention are:

[0023] (1) In the present invention, in step (3), since molybdenum foil is more easily oxidized than MoS2, the presence of molybdenum foil can weaken the reaction degree between oxygen and MoS2, so that the reaction between oxygen and MoS2 tends to defect passivation (weak reaction) rather than oxidation etching (strong reaction).

[0024] (2) In the present invention, in step (3), the reaction degree between oxygen and MoS2 can be controlled by adjusting the ratio of oxygen in argon / oxygen, gas flow rate, pressure, passivation temperature and passivation time, thereby controlling the passivation of sulfur vacancy defects.

[0025] (3) In the present invention, the number of layers of the MoS2 film can be controlled by the quality of MoCl5 and the growth time in step (2). BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a schematic diagram of the device for preparing MoS2 thin film of the present invention.

[0028] Figure 2 It is a schematic diagram of a device for passivating sulfur vacancy defects in MoS2 thin film according to the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. 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, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0031] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0032] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0033] Example 1

[0034] (1) Cleaning the quartz boat and substrate: Separately clean the quartz boat, ~2×2cm 2 Molybdenum foil and ~1×1cm 2 The heavily doped p-type SiO2 / Si substrate was placed in acetone ultrasound for 15 min, anhydrous ethanol for 15 min, deionized water for 15 min, and then blown dry with a nitrogen gun.

[0035] (2) Preparation of MoS2 thin film: a) Use an electronic scale to weigh 200 mg of S powder and 5 mg of MoCl5 powder, put the weighed S powder and MoCl5 powder into a quartz boat, and send them into two temperature zones of a tube furnace. Put the S powder into the first temperature zone, and put the MoCl5 powder and the growth substrate into the second temperature zone according to the direction of the air flow. The schematic diagram of the device is shown in the figure. Figure 1 As shown; b) under argon gas 500sccm, the first temperature zone and the second temperature zone are heated to 110°C, kept warm for 10min, and water vapor is removed; c) argon gas is introduced, and the gas flow rate and growth pressure are adjusted to 50sccm and 1000Pa respectively, and then the first temperature zone and the second temperature zone are heated to 180°C and 800°C respectively, and then kept warm for 10min to grow MoS2 thin film, and finally naturally cooled to room temperature to obtain MoS2 thin film.

[0036] (3) Sulfur vacancy defect passivation: a) Place the molybdenum foil and the MoS2 film prepared above on the top and bottom of the quartz boat respectively, and then send them into the central temperature zone of the tube furnace. The schematic diagram of the device is shown in Figure 2 As shown; b) introduce argon / oxygen mixed gas (oxygen ratio 0.5%), adjust the gas flow rate and passivation pressure to 100sccm and 1000Pa respectively, then raise the temperature to the passivation temperature of 400°C, and then keep the passivation for 10 minutes to obtain a high-quality MoS2 film after sulfur vacancy passivation.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any 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 method for passivating sulfur vacancy defects in a molybdenum disulfide (MoS2) film, comprising the following steps: (1) Cleaning the quartz boat and substrate: Place the quartz boat, molybdenum foil and growth substrate in acetone ultrasonic bath for 15 min, anhydrous ethanol for 15 min, and deionized water for 15 min, and blow dry with a nitrogen gun. (2) Preparation of MoS2 thin film: a) Use an electronic scale to weigh 30-2000 mg of sulfur (S) powder and 1-50 mg of molybdenum pentachloride (MoCl5) powder, put the weighed S powder and MoCl5 powder into a quartz boat, and send them into two temperature zones of a tube furnace. Put the S powder into the first temperature zone, and put the MoCl5 powder and the growth substrate into the second temperature zone according to the direction of the gas flow. The schematic diagram of the device is shown in Figure 1; b) Under argon 500sccm, heat the first temperature zone and the second temperature zone to 110℃, keep them warm for 10 minutes, and remove water vapor; c) Under argon atmosphere (10-200sccm), evacuate the growth chamber to the growth pressure (100-10000Pa), then heat the first temperature zone and the second temperature zone to 150-350℃ and 750-900℃ respectively, and then keep them warm for 10-30 minutes to grow MoS2 thin film, and finally cool them naturally to room temperature to obtain MoS2 thin film. (3) Sulfur vacancy defect passivation: a) Place the molybdenum foil and the previously prepared MoS2 film on the top and bottom of the quartz boat respectively, and then send them into the central temperature zone of the tube furnace. The schematic diagram of the device is shown in Figure 2; b) Introduce an argon / oxygen mixed gas, adjust the oxygen ratio, flow rate and pressure of the mixed gas to 0.01%-1%, 10-200sccm and 100-5000Pa respectively, then raise the temperature to 300-500℃, keep warm for 10-30min, and finally cool naturally to room temperature to obtain a high-quality MoS2 film after sulfur vacancy passivation.

2. A method for passivating sulfur vacancy defects in MoS2 thin film according to claim 1, characterized in that: In step (3), since molybdenum foil is more easily oxidized than MoS2, the presence of molybdenum foil can weaken the reaction between oxygen and MoS2, making the reaction between oxygen and MoS2 tend to defect passivation (weak reaction) rather than oxidation etching (strong reaction).

3. A method for passivating sulfur vacancy defects in MoS2 thin films according to claim 1, characterized in that: In step (3), by adjusting the ratio of oxygen in argon / oxygen, gas flow, pressure, passivation temperature and passivation time, the degree of reaction between oxygen and MoS2 can be controlled, thereby controlling the passivation of sulfur vacancy defects.

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