Method for preparing discrete films on same substrate by using molecular beam epitaxy technology

Abstract

The invention provides a method for preparing discrete films on the same substrate by using a molecular beam epitaxy technology, and belongs to the technical field of film preparation, the principle of the method is that a mask plate is used for shielding part of the substrate, after an evaporation source is heated to a certain temperature, molecular beams are sprayed and deposited on part of the area of the Si substrate, and after the growth of the film in the area is finished, the film is prepared. By rotating the substrate and moving the mask plate, thin films grow in other areas of the substrate, and finally, discrete thin films grow in different areas of the same substrate. According to the method disclosed by the invention, a plurality of discrete films with different components, including different heterojunctions, can be prepared on the same substrate.

Description

Technical Field

[0001] The invention belongs to the technical field of thin film preparation, and in particular relates to a method for preparing discrete thin films on the same substrate by using molecular beam epitaxy technology. Background Art

[0002] Molecular beam epitaxy (MBE) is a high-precision thin film growth technology that is widely used in semiconductors, optoelectronic devices, quantum devices and other fields. The basic principle of MBE thin film preparation is to heat the evaporation source in an ultra-high vacuum environment, increase the material temperature in the source, increase the saturated vapor pressure, and spray the corresponding molecular or atomic beam onto the substrate surface. The thin film growth is achieved through adsorption, desorption, surface diffusion migration, nucleation, reaction and other interaction processes on the substrate surface. MBE technology grows thin films slowly and is relatively easy to grow single crystal samples. The typical growth rate is 0.01-1nm / min, which is equivalent to growing an atomic monolayer per minute. Therefore, it is conducive to precise control of thickness, structure and composition, and is particularly suitable for growing superlattice materials.

[0003] At present, most of the thin films grown on a substrate using MBE can only obtain a thin film of one component or a heterojunction, which to a certain extent limits the coating efficiency and more functional and structural designs. By preparing discrete thin films of different materials and components in different regions on the same substrate, a variety of functional and structural designs can be achieved, which is of great significance for the preparation of a variety of high-performance devices and materials. For example, by integrating multiple heterostructures on the same wafer and by growing different materials in different regions on the same substrate, the design and regulation of nanostructures such as quantum dots and quantum wells can be achieved. Summary of the invention

[0004] Purpose of the invention: By preparing thin films of different components in different areas on the same substrate, a variety of functional and structural designs can be achieved, which is of great significance for the preparation of a variety of high-performance devices and materials. To this end, the present invention provides a method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology.

[0005] Technical solution, in order to achieve the above-mentioned invention object, the present invention provides a method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology, the method comprising the following steps:

[0006] (1) A Si substrate with a size of 12 mm × 24 mm × 0.5 mm is transferred to the sample holder in the molecular beam epitaxy MBE growth chamber;

[0007] (2) heating the Si substrate to 500°C and keeping it at this temperature for more than 5 hours to remove impurities on the surface of the substrate, and then cooling the Si substrate to room temperature;

[0008] (3) moving the mask to a preset position and rotating the sample holder, that is, rotating the substrate to a first preset angle;

[0009] (4) Turn on the La evaporation source and heat it to 1600-1700°C, and turn on the Ce evaporation source and heat it to 1500-1600°C;

[0010] (5) The La evaporation source baffle is opened to eject the La molecular beam, which is deposited on the Si substrate shielded by the mask. The vacuum degree during film growth is less than 1.0×10 -10 mbar, after La deposition for the first preset time, the La evaporation source baffle is closed;

[0011] (6) rotating the sample holder to a second preset angle, opening the La evaporation source baffle, opening the Ce evaporation source baffle, and depositing the molecular beam on the Si substrate shielded by the mask. After the deposition time is the second preset time, closing the evaporation source baffle;

[0012] (7) rotating the sample holder to a third preset angle, opening the La evaporation source baffle, opening the Ce evaporation source baffle, and depositing the molecular beam on the Si substrate shielded by the mask. After the deposition time is the third preset time, closing the evaporation source baffle;

[0013] (8) rotating the sample holder to a fourth preset angle, opening the Ce evaporation source baffle, depositing the molecular beam on the Si substrate shielded by the mask, and closing the evaporation source baffle after the deposition for a fourth preset time;

[0014] (9) Finish the coating and obtain a thin film with multiple discrete components.

[0015] Furthermore, in step (3), the middle part of the mask is hollowed out by 15 mm×15 mm, and the molecular beam is deposited on the substrate through the hollowed-out area, while the rest of the part is blocked.

[0016] Furthermore, in step (3), the preset position is such that 2 / 3 of the substrate is blocked.

[0017] Furthermore, in step (3), the first preset angle is 27°.

[0018] Furthermore, in step (5), before the metal La is first deposited on the substrate, it is heated to 1700° C. and maintained for more than 30 hours for degassing.

[0019] Furthermore, in step (6), the second preset angle is 117°.

[0020] Furthermore, in step (6), before the metal Ce is first deposited on the substrate, it is heated to 1600° C. and maintained for more than 30 hours for degassing.

[0021] Furthermore, in step (7), the third preset angle is 297°.

[0022] Furthermore, in step (8), the fourth preset angle is 207°.

[0023] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0024] The technical solution of the present invention can prepare discrete thin films of different materials and components in different regions on the same substrate, including different heterojunctions, which is conducive to realizing a variety of functional and structural designs and is of great significance for the preparation of a variety of high-performance devices and materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flow chart of the method of the present invention;

[0026] Figure 2 The discrete films of different materials and components prepared in Example 1 of the present invention;

[0027] Figure 3 is the elemental composition analysis of the coating region 1 of the thin film prepared in Example 1 of the present invention;

[0028] Figure 4 is the elemental composition analysis of the coating region 2 of the thin film prepared in Example 1 of the present invention;

[0029] Figure 5 is the element composition analysis of the coating region 3 of the thin film prepared in Example 1 of the present invention;

[0030] Figure 6 This is the elemental composition analysis of the coating region 4 of the thin film prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The following Example 1 is used to illustrate the present invention, but is not used to limit the protection scope of the present invention.

[0032] Example 1

[0033] (1) A Si substrate with a size of 12 mm × 24 mm × 0.5 mm is transferred to a molecular beam epitaxy (MBE) growth chamber;

[0034] (2) heating the Si substrate to 500°C and keeping it at this temperature for more than 5 hours to remove impurities on the surface of the substrate, and then cooling the Si substrate to room temperature;

[0035] (3) moving the mask to a preset position and rotating the sample holder to an angle of 27°;

[0036] (4) Turn on the La evaporation source and heat to 1660°C, and turn on the Ce evaporation source and heat to 1580°C;

[0037] (5) The molecular beam current of the La evaporation source is measured using a crystal oscillator. The molecular beam current of Ce evaporation source is

[0038] (6) The La evaporation source baffle is opened to eject the La molecular beam, which is deposited on the Si substrate shielded by the mask. The vacuum degree during film growth is less than 1.0×10 -10 mbar, after La deposition for 100 min, the La evaporation source baffle was closed;

[0039] (7) rotating the sample holder to an angle of 117°, opening the La evaporation source baffle for 16 minutes, and opening the Ce evaporation source baffle for 88 minutes, i.e., deposition for 88 minutes, with the molecular beam deposited on the Si substrate shielded by the mask;

[0040] (8) rotating the sample holder to an angle of 297°, opening the La evaporation source baffle for 23 minutes, and opening the Ce evaporation source baffle for 83 minutes, i.e., deposition for 83 minutes, with the molecular beam deposited on the Si substrate shielded by the mask;

[0041] (9) Rotate the sample holder to 207°, open the Ce evaporation source baffle for 100 minutes, and deposit the molecular beam on the Si substrate shielded by the mask;

[0042] (10) Finish the coating to obtain thin films with multiple discrete components.

[0043] Take out the above film and take a photo to get Figure 2 It can be seen that multiple discrete thin films of different components with distinct regions are obtained on the same substrate, among which regions 1, 2, 3, and 4 are thin films of different components, and regions 5, 6, 7, and 8 are different heterojunctions. Figure 3-Figure 6 Corresponding to Figure 2 Energy dispersive X-ray spectroscopy (EDS) results of regions 1, 2, 3, and 4 show that the components in each region are different and are basically consistent with the expected experimental results, as shown in Table 1.

[0044] Table 1

[0045]

Claims

1. A method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology, characterized in that: The method comprises the following steps: (1) A Si substrate with a size of 12 mm × 24 mm × 0.5 mm is transferred to the sample holder in the molecular beam epitaxy MBE growth chamber; (2) heating the Si substrate to 500°C and keeping it at this temperature for more than 5 hours to remove impurities on the surface of the substrate, and then cooling the Si substrate to room temperature; (3) moving the mask to a preset position and rotating the sample holder, that is, rotating the substrate to a first preset angle; (4) Turn on the La evaporation source and heat it to 1600-1700°C, and turn on the Ce evaporation source and heat it to 1500-1600°C; (5) The La evaporation source baffle is opened to eject the La molecular beam, which is deposited on the Si substrate shielded by the mask. The vacuum degree during film growth is less than 1.0×10 -10 mbar, after La deposition for the first preset time, the La evaporation source baffle is closed; (6) rotating the sample holder to a second preset angle, opening the La evaporation source baffle, opening the Ce evaporation source baffle, and depositing the molecular beam on the Si substrate shielded by the mask. After the deposition time is the second preset time, closing the evaporation source baffle; (7) rotating the sample holder to a third preset angle, opening the La evaporation source baffle, opening the Ce evaporation source baffle, and depositing the molecular beam on the Si substrate shielded by the mask. After the deposition time is the third preset time, closing the evaporation source baffle; (8) rotating the sample holder to a fourth preset angle, opening the Ce evaporation source baffle, depositing the molecular beam on the Si substrate shielded by the mask, and closing the evaporation source baffle after the deposition for a fourth preset time; (9) Finish the coating and obtain a thin film with multiple discrete components.

2. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (3), the middle part of the mask is hollowed out by 15 mm×15 mm, and the molecular beam is deposited on the substrate through the hollowed-out area, while the rest of the part is blocked.

3. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (3), the preset position is such that 2 / 3 of the substrate is blocked.

4. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (3), the first preset angle is 27°.

5. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (5), before the metal La is first deposited on the substrate, it is heated to 1700° C. and maintained for more than 30 hours for degassing.

6. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (6), the second preset angle is 117°.

7. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (6), before the metal Ce is first deposited on the substrate, it is heated to 1600° C. and maintained for more than 30 hours for degassing.

8. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (7), the third preset angle is 297°.

9. The method for preparing discrete thin films on the same substrate using molecular beam epitaxy technology according to claim 1, characterized in that: In step (8), the fourth preset angle is 207°.

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