Method for preparing high-quality one-dimensional iron-antimony nanowire by utilizing molecular beam epitaxial growth technology and application

Abstract

The invention discloses a method for preparing a high-quality one-dimensional iron-antimony nanowire by utilizing a molecular beam epitaxial growth technology and application, and belongs to the technical field of semiconductor materials. According to the method, a strontium titanate single crystal is used as a substrate, and the substrate is pretreated under an ultrahigh vacuum condition until regular steps are formed on the surface of the substrate; then an iron source and an antimony source are used as evaporation sources, an ultrahigh vacuum environment and precise temperature control are combined, and the high-quality one-dimensional iron-antimony nanowire is prepared on the pretreated substrate through the molecular beam epitaxial growth technology. The prepared nanowires are uniformly distributed on the surface of the substrate, the height is 8.03 nm, and the width is 2.7 nm. A scanning tunnel spectrum result shows that the energy gap of the iron-antimony nanowire is obviously increased relative to that of an iron-antimony thin film, and the adjustability of the semiconductor band gap is shown. The method has remarkable advantages in the aspect of accurately controlling and preparing narrow-band-gap semiconductor nanowires with uniform sizes and nanometer widths, and an excellent material basis is provided for research and development of new-generation semiconductor devices.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor material technology, and more specifically, to a method and application of preparing high-quality one-dimensional iron-antimony nanowires by using molecular beam epitaxial growth technology. Background Art

[0002] Nanowires, which are 1,000 times or more thinner than human hair, have high aspect ratios and unique physical and chemical properties. Since the concept of nanowires was first proposed in 1973, hundreds of nanowires with different compositions and aspect ratios have been synthesized and widely used in electronics, optoelectronics, energy storage, and biology. Due to their one-dimensional characteristics, nanowires exhibit unique physical and chemical properties in terms of quantum size effects, surface effects, and interface effects. Compared with bulk materials and thin film materials, nanowires have significant differences in electron transport, photoelectric response, thermal conductivity, and magnetic properties. They are the most ideal and convenient building blocks for the development of a new generation of high-performance electronic devices, and are also the key foundation for the construction of ultra-efficient photoelectric detection and regulation and novel micro-nano electromechanical devices.

[0003] The choice of nanowire preparation method is crucial to achieve high-quality and controllable nanostructures. Common preparation methods currently include chemical vapor deposition, electrochemical deposition, pulsed laser deposition, hydrothermal method and molecular beam epitaxy. Among them, molecular beam epitaxy technology has become an important method in the preparation of semiconductor nanowires due to its high-precision control under ultra-high vacuum conditions. In recent years, there have been many reports on the research of gallium antimonide nanowires. Gallium antimonide nanowires prepared by chemical vapor deposition and molecular beam epitaxy technology are usually large in size, and their width is usually tens or even hundreds of nanometers. Moreover, gallium antimonide nanowires themselves do not have magnetism, which limits their application potential in magnetism-related fields such as spin electronics, magnetic storage and magnetic sensors. This shows that the development of nanowire materials with magnetism and smaller size is of great significance for expanding their application in high-performance electronic devices and spin electronics.

[0004] Iron antimony is a narrow bandgap semiconductor with an energy gap of 17.4 meV, making it an excellent candidate material for infrared photodetection. As a typical non-van der Waals two-dimensional ferromagnetic material, the Curie temperature of iron antimony thin film is higher than room temperature. So far, there has been no report on the preparation of iron antimony nanowires, including molecular beam epitaxy technology. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects of the prior art, and to provide a method and application for preparing high-quality one-dimensional iron-antimony nanowires using molecular beam epitaxial growth technology, which realizes the preparation of high-quality iron-antimony nanowires for the first time. The method uses strontium titanate single crystal as a substrate, degassing the substrate and annealing it at high temperature under ultra-high vacuum conditions until regular steps are formed on its surface; then, using iron source and antimony source as evaporation sources, combined with ultra-high vacuum environment and precise temperature control, molecular beam epitaxial growth technology is used to successfully prepare high-quality one-dimensional iron-antimony nanowires on the pretreated substrate, providing an excellent material foundation for the research and development of a new generation of semiconductor devices.

[0006] To achieve the above object, the technical solution of the present invention is as follows: A method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology comprises the following steps: (1) After cleaning, the strontium titanate substrate is loaded into a sample holder, and then introduced into a molecular beam epitaxy chamber, and the strontium titanate substrate is pretreated under ultra-high vacuum conditions, so that the surface morphology of the pretreated substrate exhibits regular steps, and the width of the steps is 50 nm to 200 nm; (2) Using iron source and antimony source as evaporation sources, molecular beam epitaxial growth technology was used to grow iron-antimony nanowires on the pretreated substrate. During the growth process, the evaporation temperature of the iron source was 1170℃~1230℃, the evaporation temperature of the antimony source was 350℃~430℃, the temperature of the pretreated substrate was maintained at 380℃~420℃, the growth rate was 0.015 layer / min~0.019 layer / min, the growth time was 26min~34min, and the iron-antimony nanowire was 8.03Å high and 2.7nm wide.

[0007] Optionally, in step (2), the evaporation temperature of the antimony source is 380°C to 400°C, and the temperature of the pretreated substrate is maintained at 390°C to 410°C.

[0008] Optionally, in step (2), the heating rates of the pretreated substrate and the antimony source are both 14°C / min to 16°C / min; the heating rate of the iron source is 28°C / min to 32°C / min; and the vacuum is maintained at 5×10 -10 mbar~1×10 - 9 mbar.

[0009] Optionally, in step (2), the heating rates of the pretreated substrate and the antimony source are 14.5°C / min to 15.5°C / min; and the heating rate of the iron source is 29°C / min to 31°C / min.

[0010] Optionally, in step (2), the ratio of the iron source beam current to the antimony source beam current is 1:(9-11); the iron source beam current during the growth process is 54 min / layer-66 min / layer, and the antimony source beam current is 5.4 min / layer-6.6 min / layer.

[0011] Optionally, in step (1), the pretreatment includes: -10 mbar~1×10 -9 Under ultra-high vacuum conditions of 100 mbar, the strontium titanate substrate is heated to 380°C to 420°C, kept warm for 1.5h to 2.5h, and then degassed. The substrate is then heated to 800°C to 1000°C and kept warm for 0.25h to 0.75h.

[0012] Optionally, in step (1), the strontium titanate substrate is a SrTiO3 (001) wafer or a SrTiO3 (111) wafer.

[0013] Optionally, in step (1), the cleaning includes: placing the strontium titanate substrate in anhydrous ethanol, ultrasonically cleaning it for 15 minutes, and after cleaning, taking it out with tweezers and gently wiping off excess ethanol with dust-free paper.

[0014] The present invention also discloses a high-quality one-dimensional iron-antimony nanowire prepared by the method for preparing the high-quality one-dimensional iron-antimony nanowire using the molecular beam epitaxial growth technology as described above.

[0015] The present invention also discloses an application of high-quality one-dimensional iron-antimony nanowires prepared by the method for preparing high-quality one-dimensional iron-antimony nanowires using molecular beam epitaxial growth technology in new generation semiconductor devices.

[0016] Implementing the embodiments of the present invention will have the following beneficial effects: (1) The preparation method provided by the present invention uses strontium titanate single crystal as a substrate, uses an iron source and an antimony source as reaction materials, and for the first time uses molecular beam epitaxial growth technology in combination with an ultra-high vacuum environment and precise temperature control to successfully prepare high-quality one-dimensional iron-antimony nanowires. The entire growth process is carried out under ultra-high vacuum, using extremely high-purity elemental materials, effectively avoiding interference from impurities, and obtaining extremely high-purity nanowires.

[0017] (2) The nanowires grown by the molecular beam epitaxy equipment used in the present invention are distributed all over the surface of the film, with a height of 8.03Å and a width of 2.7nm. The length of the nanowires in each 500nm×500nm area is 1461.4nm, achieving high-density nanowire growth.

[0018] (3) The preparation method of the present invention has the advantages of precise control and high quality, providing an ideal nanowire material for the development of a new generation of semiconductor devices. It is expected to be applied to information storage, transmission and processing, and will play an important role in the post-Moore era.

[0019] In summary, the present invention successfully prepared high-quality one-dimensional iron-antimony nanowires by selecting a strontium titanate single crystal substrate, using iron and antimony as evaporation sources, combining substrate pretreatment and optimization of growth conditions, and using molecular beam epitaxial growth technology. The nanowires are 8.03Å high and 2.7nm wide, and the length of the nanowires per 500nm×500nm is 1461.4nm. The scanning tunneling spectrum results show that the energy gap of the iron-antimony nanowires is significantly increased relative to that of the iron-antimony film, from 17.4meV to 37.5meV, showing the adjustability of the semiconductor band gap, and is expected to be used in the field of infrared photodetectors. Compared with the existing preparation technology, the present invention overcomes the problems of the existing technology in large-scale production of nanowires and high stability control, and expands the new nanowire preparation process. The method of the present invention has the advantages of precise control and high crystal quality, and has significant advantages in the precise control of the preparation of narrow-bandgap semiconductor nanowires, providing an excellent material basis for the research and development of a new generation of semiconductor devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to an embodiment of the present invention.

[0021] Figure 2 The overall and microscopic structures of the iron-antimony nanowires of Example 1 of the present invention are shown.

[0022] Figure 3 This is a dimensional diagram of the iron-antimony nanowires of Example 1 of the present invention.

[0023] Figure 4 This is a length statistics diagram of the iron-antimony nanowires of Example 1 of the present invention.

[0024] Figure 5 This is a scanning tunneling microscopy spectrum of the iron antimony nanowires of Example 1 of the present invention.

[0025] Figure 6 This is a diagram showing the STM measurement results of the iron-antimony nanowires of Examples 1-5 of the present invention under different temperature conditions of the substrate after pretreatment.

[0026] Figure 7 Figure 3 is a graph showing the STM measurement results of the iron-antimony nanowires of Example 1 and Examples 6-9 of the present invention under different evaporation temperature conditions of the iron source.

[0027] Figure 8Figure 3 is a graph showing the STM measurement results of the iron-antimony nanowires of Example 1 and Examples 10-13 of the present invention under different evaporation temperature conditions of the antimony source. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0029] Example 1 like Figure 1 As shown, the method of preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology of the present invention comprises the following steps: (1) Place the strontium titanate substrate (SrTiO3 (001) wafer) in anhydrous ethanol and ultrasonically clean it for 15 minutes. After cleaning, pick it out with tweezers and gently wipe off the excess ethanol with dust-free paper. Then put it into the sample holder and transfer it into the molecular beam epitaxy cavity. -10 Under ultra-high vacuum conditions of mbar, the strontium titanate substrate was heated to 400°C, kept warm for 2 hours and then degassed. The substrate was then heated to 900°C and kept warm for 0.5 hours. The surface morphology of the pretreated substrate showed regular steps.

[0030] (2) Using iron source and antimony source as evaporation sources, the iron antimony nanowires are grown on the pretreated substrate by molecular beam epitaxy. During the growth process, the iron source is heated to 1200°C at a rate of 15°C / min, the antimony source is heated to 390°C at a rate of 30°C / min, the pretreated substrate is heated to 400°C at a rate of 15°C / min, the ratio of the iron source beam current to the antimony source beam current is 1:10, the iron source beam current during the growth process is 60min / layer, the antimony source beam current is 6min / layer, the growth rate is 0.017 layer / min, and the growth time is 30min.

[0031] Test Example 1 Scanning tunneling microscope test The one-dimensional iron antimony nanowires obtained in the embodiment were measured using a scanning tunneling microscope. The testing instrument was a low-temperature scanning tunneling microscope (LT-STM) produced by Scienta Omicron of Germany. The testing temperature range was 4 K-300 K. Figure 2 As shown in the figure, the morphology of nanowires can be measured by scanning tunneling microscopy. The growth of high-quality nanowires is achieved by precisely controlling the evaporation temperature of the iron source and Sb source, the heating temperature of the substrate, and the growth time. STM can accurately measure the size of the nanowires, with a height of 8.03 Å and a diameter of 2.7 nm ( Figure 3 ). The total length of the nanowires included in the 500nm×500nm STM image is as high as 1461.4 nm ( Figure 4). The energy gap of FeSb thin film is 17.4 meV, and the energy gap of FeSb nanowire is 37.5 meV. Compared with FeSb nanoislands, the energy gap near the Fermi surface of nanowire is significantly increased relative to that of thin film ( Figure 5 ).

[0032] Embodiment 2-5 The difference between Example 2-5 and Example 1 is that the temperature of the substrate after pretreatment in step (2) is changed. Except for the above difference, other operations are the same and will not be repeated here. In Example 2-5, the temperature of the substrate after pretreatment is set to 370°C, 390°C, 410°C and 430°C respectively. The STM measurement results are as follows: Figure 6 As shown. It is not difficult to see that the substrate temperature has a significant effect on the morphology of the sample. When the temperature is low, the film is more likely to form continuous coverage, but it is difficult to form a quasi-one-dimensional nanowire structure. As the temperature rises, the film gradually decomposes to form nanowires and island structures, in which the nanowires act as a connection between the islands. However, when the temperature is too high, the nanowire structure is no longer stable and eventually disappears. The above results show that substrate temperature is a key parameter for regulating film morphology and nanowire formation.

[0033] Embodiment 6-9 The difference between Example 6-9 and Example 1 is that the evaporation temperature of the iron source in step (2) is changed. Except for the above difference, other operations are the same and will not be repeated here. In Examples 6-9, the evaporation temperatures of the iron source are set to 1140°C, 1170°C, 1230°C and 1260°C respectively. The STM measurement results are as follows: Figure 7 When the temperature is too high (>1230℃) or too low (<1170℃), the system cannot form a continuous film, and it is even more difficult to obtain nanowires and island structures. However, when the temperature is adjusted to around 1200℃, the formation of FeSb islands and nanowires is successfully observed. This phenomenon confirms the key role of the iron source evaporation temperature in the nanowire formation process.

[0034] Examples 10-13 Compared with Example 1, the difference between Example 10-13 is that the evaporation temperature of the antimony source in step (2) is changed. Except for the above difference, other operations are the same and will not be repeated here. In Examples 10-13, the evaporation temperatures of the antimony source are set to 340°C, 380°C, 400°C and 440°C respectively. The STM measurement results are as follows: Figure 8 shown.

[0035] Embodiment 14 The method of preparing high-quality one-dimensional iron antimony nanowires by using molecular beam epitaxial growth technology of the present invention comprises the following steps: (1) Place the strontium titanate substrate (SrTiO3 (111) wafer) in anhydrous ethanol and ultrasonically clean it for 15 minutes. After cleaning, pick it out with tweezers and gently wipe off the excess ethanol with dust-free paper. Then put it into the sample holder and transfer it into the molecular beam epitaxy cavity. -9 Under ultra-high vacuum conditions of mbar, the strontium titanate substrate was heated to 380°C, kept warm for 2 hours and then degassed. The substrate was then heated to 800°C and kept warm for 0.75 hours. The surface morphology of the pretreated substrate showed regular steps.

[0036] (2) Using iron source and antimony source as evaporation sources, the iron antimony nanowires were grown on the pretreated substrate by molecular beam epitaxy. During the growth process, the iron source was heated to 1200°C at a rate of 16°C / min, the antimony source was heated to 350°C at a rate of 32°C / min, the pretreated substrate was heated to 380°C at a rate of 16°C / min, the ratio of the iron source beam current to the antimony source beam current was 1:10, the iron source beam current during the growth process was 60 min / layer, the antimony source beam current was 6 min / layer, the growth rate was 0.019 layer / min, and the growth time was 26 min.

[0037] Embodiment 15 The method of preparing high-quality one-dimensional iron antimony nanowires by using molecular beam epitaxial growth technology of the present invention comprises the following steps: (1) Place the strontium titanate substrate (SrTiO3 (111) wafer) in anhydrous ethanol and ultrasonically clean it for 15 minutes. After cleaning, pick it out with tweezers and gently wipe off the excess ethanol with dust-free paper. Then put it into the sample holder and transfer it into the molecular beam epitaxy cavity. -9 Under ultra-high vacuum conditions of mbar, the strontium titanate substrate was heated to 420°C, kept warm for 2 hours and then degassed. The substrate was then heated to 1000°C and kept warm for 0.5 hours. The surface morphology of the pretreated substrate showed regular steps.

[0038] (2) Using iron source and antimony source as evaporation sources, the iron antimony nanowires were grown on the pretreated substrate by molecular beam epitaxy. During the growth process, the iron source was heated to 1200°C at a rate of 15°C / min, the antimony source was heated to 430°C at a rate of 30°C / min, the pretreated substrate was heated to 420°C at a rate of 15°C / min, the ratio of the iron source beam current to the antimony source beam current was 1:10, the iron source beam current during the growth process was 60min / layer, the antimony source beam current was 6min / layer, the growth rate was 0.015 layer / min, and the growth time was 34min.

[0039] The high-quality one-dimensional iron-antimony nanowires prepared in Example 14-Example 15 have the same effect as that in Example 1.

[0040] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology, characterized in that: The following steps are involved: (1) After cleaning, the strontium titanate substrate is loaded into a sample holder, and then introduced into a molecular beam epitaxy chamber, and the strontium titanate substrate is pretreated under ultra-high vacuum conditions, so that the surface morphology of the pretreated substrate exhibits regular steps, and the width of the steps is 50 nm to 200 nm; (2) Using iron source and antimony source as evaporation sources, molecular beam epitaxial growth technology was used to grow iron-antimony nanowires on the pretreated substrate. During the growth process, the evaporation temperature of the iron source was 1170℃~1230℃, the evaporation temperature of the antimony source was 350℃~430℃, the temperature of the pretreated substrate was maintained at 380℃~420℃, the growth rate was 0.015 layer / min~0.019 layer / min, the growth time was 26min~34min, and the iron-antimony nanowire was 8.03Å high and 2.7nm wide.

2. The method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to claim 1, characterized in that: In step (2), the evaporation temperature of the antimony source is 380°C to 400°C, and the temperature of the pretreated substrate is maintained at 390°C to 410°C.

3. The method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to claim 1, characterized in that: In step (2), the heating rates of the pretreated substrate and the antimony source are both 14°C / min to 16°C / min; the heating rate of the iron source is 28°C / min to 32°C / min; and the vacuum is maintained at 5×10 -10 mbar~1×10 - 9 mbar.

4. The method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to claim 3, characterized in that: In step (2), the heating rates of the pretreated substrate and the antimony source are 14.5°C / min to 15.5°C / min; the heating rate of the iron source is 29°C / min to 31°C / min.

5. The method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to claim 3, characterized in that: In step (2), the ratio of the iron source beam current to the antimony source beam current is 1:(9-11); during the growth process, the iron source beam current is 54 min / layer-66 min / layer, and the antimony source beam current is 5.4 min / layer-6.6 min / layer.

6. The method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to claim 3, characterized in that: In step (1), the pretreatment includes: -10 mbar~1×10 -9 Under ultra-high vacuum conditions of 100 mbar, the strontium titanate substrate is heated to 380°C to 420°C, kept warm for 1.5h to 2.5h, and then degassed. The substrate is then heated to 800°C to 1000°C and kept warm for 0.25h to 0.75h.

7. The method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to claim 3, characterized in that: In step (1), the strontium titanate substrate is a SrTiO3 (001) wafer or a SrTiO3 (111) wafer.

8. The method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology according to claim 3, characterized in that: In step (1), the cleaning comprises: placing the strontium titanate substrate in anhydrous ethanol, ultrasonically cleaning it for 15 minutes, taking it out with tweezers after cleaning, and gently wiping off excess ethanol with dust-free paper.

9. A high-quality one-dimensional iron antimony nanowire prepared by the method for preparing high-quality one-dimensional iron antimony nanowire using molecular beam epitaxial growth technology as described in any one of claims 1 to 8.

10. Application of high-quality one-dimensional iron antimony nanowires prepared by the method for preparing high-quality one-dimensional iron antimony nanowires using molecular beam epitaxial growth technology as described in any one of claims 1 to 8 in new generation semiconductor devices.

Images