Method and application for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology

Abstract

The present invention discloses a method for preparing high-quality one-dimensional iron antimonide nanowires by molecular beam epitaxy growth technology and its application, belonging to the technical field of semiconductor materials. This method uses strontium titanate single crystal as a substrate, pre-treats the substrate under ultra-high vacuum conditions until regular steps are formed on its surface; subsequently, iron source and antimony source are used as evaporation sources, combined with ultra-high vacuum environment and precise temperature control, and high-quality one-dimensional iron antimonide nanowires are prepared on the pre-treated substrate by molecular beam epitaxy growth technology. The prepared nanowires are uniformly distributed on the surface of the substrate, with a height of 8.03 Å and a width of 2.7 nm. The results of scanning tunneling spectroscopy show that the energy gap of the iron antimonide nanowires increases significantly relative to the iron antimonide thin film, showing the tunability of the semiconductor band gap. The method of the present invention has significant advantages in precisely controlling the preparation of narrow-bandgap semiconductor nanowires with uniform size and nanometer width, providing an excellent material basis for the research and development of new-generation semiconductor devices.

Description

Technical Field

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

[0002] Nanowires, which are 1000 times or more thinner than human hair, have a high aspect ratio 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 the fields of electronics, optoelectronics, energy storage, and biology. Due to their one-dimensional characteristics, nanowires exhibit unique physical and chemical properties in aspects such as quantum size effect, surface effect, and interface effect. Compared with bulk materials and thin film materials, nanowires have significant differences in electron transport, optoelectronic response, thermal conductivity, and magnetic properties, and are the most ideal and convenient building blocks for developing a new generation of high-performance electronic devices, and are also the key foundation for constructing ultra-high-efficiency optoelectronic detection and regulation and novel micro-nano electromechanical devices.

[0003] The selection of the nanowire preparation method is crucial for achieving high-quality and controllable nanostructures. Currently, common preparation methods include chemical vapor deposition, electrochemical deposition, pulsed laser deposition, hydrothermal method, and molecular beam epitaxy, etc. 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. The gallium antimonide nanowires prepared by chemical vapor deposition and molecular beam epitaxy technology usually have relatively large sizes, and their widths usually reach dozens or even hundreds of nanometers. Moreover, gallium antimonide nanowires themselves do not have magnetism, which limits their application potential in magnetic-related fields such as spintronics, magnetic storage, and magnetic sensors. This indicates that developing nanowire materials with magnetism and smaller sizes is of great significance for expanding their applications in the fields of high-performance electronic devices and spintronics.

[0004] Iron antimonide belongs to narrow-bandgap semiconductors with an energy gap of 17.4 meV and is an excellent candidate material for infrared optoelectronic detection. As a typical non-van der Waals two-dimensional ferromagnetic material, the Curie temperature of iron antimonide thin films is higher than room temperature. So far, there has been no report on the preparation of iron antimonide nanowires, including molecular beam epitaxy technology. Summary of the Invention

[0005] The object of the present invention is to overcome the above-mentioned defects existing in the prior art, and to provide a method and application for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology. For the first time, the preparation of high-quality iron antimonide nanowires is realized. This method uses strontium titanate single crystal as the substrate, degasses the substrate under ultra-high vacuum conditions and performs high-temperature annealing until regular steps are formed on its surface. Subsequently, using iron source and antimony source as evaporation sources, combined with ultra-high vacuum environment and precise temperature control, high-quality one-dimensional iron antimonide nanowires are successfully prepared on the pretreated substrate through molecular beam epitaxy growth technology, providing an excellent material basis 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:

[0007] A method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology, comprising the following steps:

[0008] (1) After cleaning the strontium titanate substrate, it is loaded into the sample holder and introduced into the molecular beam epitaxy chamber. The strontium titanate substrate is pretreated under ultra-high vacuum conditions so that the surface morphology of the pretreated substrate shows regular steps, and the width of the steps is 50 nm to 200 nm;

[0009] (2) Using iron source and antimony source as evaporation sources, iron antimonide nanowires are grown on the pretreated substrate by using molecular beam epitaxy growth technology. During the growth process, the evaporation temperature of the iron source is 1170 °C to 1230 °C, the evaporation temperature of the antimony source is 350 °C to 430 °C, the temperature of the pretreated substrate is maintained at 380 °C to 420 °C, the growth rate is 0.015 layers / min to 0.019 layers / min, the growth time is 26 min to 34 min, and the height of the iron antimonide nanowires is 8.03 Å and the width is 2.7 nm.

[0010] 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.

[0011] 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; the vacuum is maintained at 5×10 -10 mbar to 1×10 - 9 mbar.

[0012] 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; the heating rate of the iron source is 29 °C / min to 31 °C / min.

[0013] 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 to 66 min / layer, and the antimony source beam current is 5.4 min / layer to 6.6 min / layer.

[0014] Optionally, in step (1), the pre-treatment includes: under an ultra-high vacuum condition of 5×10 -10 mbar to 1×10 -9 mbar, heating the strontium titanate substrate to 380°C to 420°C, holding for 1.5 h to 2.5 h for degassing, and then heating the substrate to 800°C to 1000°C and holding for 0.25 h to 0.75 h.

[0015] Optionally, in step (1), the strontium titanate substrate is a SrTiO3(001) wafer or a SrTiO3(111) wafer.

[0016] Optionally, in step (1), the cleaning includes: placing the strontium titanate substrate in absolute ethanol, ultrasonically cleaning for 15 minutes, taking it out with tweezers after cleaning, and gently wiping off the excess ethanol with a dust-free paper.

[0017] The present invention also discloses a high-quality one-dimensional iron antimonide nanowire prepared by the method for preparing a high-quality one-dimensional iron antimonide nanowire using molecular beam epitaxy growth technology as described above.

[0018] The present invention also discloses the application of a high-quality one-dimensional iron antimonide nanowire prepared by the method for preparing a high-quality one-dimensional iron antimonide nanowire using molecular beam epitaxy growth technology as described above in a new generation of semiconductor devices.

[0019] Implementing the embodiments of the present invention will have the following beneficial effects:

[0020] (1) The preparation method provided by the present invention selects a strontium titanate single crystal as the substrate, uses an iron source and an antimony source as reaction materials, and for the first time uses molecular beam epitaxy growth technology in combination with an ultra-high vacuum environment and precise temperature control to successfully prepare high-quality one-dimensional iron antimonide nanowires. The entire growth process is carried out under ultra-high vacuum, using extremely high-purity elemental materials, effectively avoiding the interference of impurities, and high-purity nanowires can be obtained.

[0021] (2) The nanowires grown by the molecular beam epitaxy equipment used in the present invention are distributed on the surface of the thin film, with a height of 8.03 Å, a width of 2.7 nm, and the length of the nanowires contained in each 500 nm×500 nm is 1461.4 nm, realizing high-density nanowire growth.

[0022] (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.

[0023] In summary, through the selection of strontium titanate single crystal substrate, using iron and antimony as evaporation sources, combined with the optimization of substrate pretreatment and growth conditions, high-quality one-dimensional iron-antimony nanowires are successfully prepared by molecular beam epitaxy growth technology. The nanowires have a height of 8.03 Å, a width of 2.7 nm, and the length of the nanowires contained in each 500 nm × 500 nm is 1461.4 nm. The scanning tunneling spectroscopy results show that the energy gap of the iron-antimony nanowires increases significantly compared with the iron-antimony thin film, from 17.4 meV to 37.5 meV, showing the tunability of the semiconductor band gap, and is expected to be used in the field of infrared photodetectors. Compared with the existing preparation technologies, the present invention overcomes the problems existing in the large-scale production of nanowires and the control of high stability in the prior art, and expands the new nanowire preparation process. The method of the present invention has the advantages of precise control and high crystallization quality, and has significant advantages in precisely controlling 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

[0024] Figure 1 It is a schematic diagram of the method for preparing high-quality one-dimensional iron-antimony nanowires by molecular beam epitaxy growth technology according to an embodiment of the present invention.

[0025] Figure 2 It is the overall and microscopic structure diagrams of the iron-antimony nanowires of Example 1 of the present invention.

[0026] Figure 3 It is the size diagram of the iron-antimony nanowires of Example 1 of the present invention.

[0027] Figure 4 It is the length statistical diagram of the iron-antimony nanowires of Example 1 of the present invention.

[0028] Figure 5 It is the scanning tunneling microscopy spectrum of the iron-antimony nanowires of Example 1 of the present invention.

[0029] Figure 6 It is the STM measurement result diagram of the iron-antimony nanowires of Examples 1-5 of the present invention under the temperature conditions of different pretreated substrates.

[0030] Figure 7 It is the STM measurement result diagram of the iron-antimony nanowires of Example 1 and Examples 6-9 of the present invention under the evaporation temperature conditions of different iron sources.

[0031] Figure 8STM measurement results of the iron-antimony nanowires in Example 1 and Examples 10-13 of the present invention under evaporation temperature conditions of different antimony sources. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0033] Example 1

[0034] As Figure 1 shown, the method for preparing high-quality one-dimensional iron-antimony nanowires by using molecular beam epitaxy growth technology of the present invention includes the following steps:

[0035] (1) Place the strontium titanate substrate (SrTiO3(001) wafer) into absolute ethanol, ultrasonically clean it for 15 minutes, after cleaning, pick it out with tweezers, gently wipe off the excess ethanol with dust-free paper, then load it into the sample holder, transfer it into the molecular beam epitaxy chamber, and under the ultra-high vacuum condition of 5×10 -10 mbar, heat the strontium titanate substrate to 400 °C, keep it warm for 2 h and then degas it, and then heat the substrate to 900 °C and keep it warm for 0.5 h. The surface morphology of the pretreated substrate shows regular steps.

[0036] (2) Using iron source and antimony source as evaporation sources, grow iron-antimony nanowires on the pretreated substrate by using molecular beam epitaxy growth technology. 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 60 min / layer, the antimony source beam current is 6 min / layer, the growth rate is 0.017 layer / min, and the growth time is 30 min.

[0037] Test Example 1

[0038] Scanning tunneling microscope test

[0039] Measure the one-dimensional iron-antimony nanowires obtained in the example by using a scanning tunneling microscope. The test instrument is a low-temperature scanning tunneling microscope (LT-STM) produced by Scienta Omicron Company of Germany, and the test temperature range is 4 K - 300 K. As Figure 2 shown, through the scanning tunneling microscope, the morphology of the nanowires can be measured. By precisely controlling the evaporation temperature of the iron source and the Sb source, the heating temperature of the substrate, and the growth time, the growth of high-quality nanowires is achieved. 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). Count the nanowires contained in the STM image of 500nm×500nm, and the total length is as high as 1461.4 nm ( Figure 4 ). The energy gap of the iron antimonide thin film is 17.4 meV, and the energy gap of the iron antimonide nanowire is 37.5 meV. Compared with the iron antimonide nanoisland, the energy gap pair near the Fermi surface of the nanowire is significantly increased relative to the thin film ( Figure 5 ).

[0040] Example 2-5

[0041] Compared with Example 1, Example 2-5 is different in that the temperature of the pretreated substrate in step (2) is changed. Except for the above differences, other operations are the same and will not be elaborated here; in Example 2-5, the temperatures of the pretreated substrate are set to 370 °C, 390 °C, 410 °C, and 430 °C respectively, and the STM measurement results are as Figure 6 shown. It is not difficult to see that the substrate temperature has a significant impact on the morphology of the sample. When the temperature is low, the thin film is more likely to form a continuous coverage, but it is difficult to form a quasi-one-dimensional nanowire structure. As the temperature increases, the thin film gradually decomposes, forming a nanowire and island structure, where the nanowires play a connecting role 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 the substrate temperature is a key parameter for regulating the morphology of the thin film and the formation of nanowires.

[0042] Example 6-9

[0043] Compared with Example 1, Example 6-9 is different in that the evaporation temperature of the iron source in step (2) is changed. Except for the above differences, other operations are the same and will not be elaborated here; in Example 6-9, the evaporation temperatures of the iron source are set to 1140 °C, 1170 °C, 1230 °C, and 1260 °C respectively, and the STM measurement results are as Figure 7 shown. When the temperature is too high (>1230 °C) or too low (<1170 °C), the system cannot form a continuous thin film, and it is more difficult to obtain a nanowire and island structure. However, when the temperature is adjusted to around 1200 °C, the formation of FeSb islands and nanowires is successfully observed, which confirms the key role of the iron source evaporation temperature in the formation process of nanowires.

[0044] Example 10-13

[0045] Compared with Example 1, Example 10-13 is different in that the evaporation temperature of the antimony source in step (2) is changed. Except for the above differences, other operations are the same and will not be elaborated here; in Example 10-13, the evaporation temperatures of the antimony source are set to 340 °C, 380 °C, 400 °C, and 440 °C respectively, and the STM measurement results are as Figure 8 shown.

[0046] Example 14

[0047] The method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology according to the present invention comprises the following steps:

[0048] (1) Place the strontium titanate substrate (SrTiO3 (111) wafer) into absolute ethanol, ultrasonically clean it for 15 minutes, pick it out with tweezers after cleaning, gently wipe off the excess ethanol with lint-free paper, then load it into the sample holder, transfer it into the molecular beam epitaxy chamber, and under the ultra-high vacuum condition of 1×10 -9 mbar, heat the strontium titanate substrate to 380°C, keep it warm for 2 h and then degas it, and then heat the substrate to 800°C, keep it warm for 0.75 h. The surface morphology of the pretreated substrate shows regular steps.

[0049] (2) Use iron source and antimony source as evaporation sources, and grow iron antimonide nanowires on the pretreated substrate by using molecular beam epitaxy growth technology. During the growth process, the iron source is heated to 1200°C at a rate of 16°C / min, the antimony source is heated to 350°C at a rate of 32°C / min, the pretreated substrate is 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 is 1:10, the iron source beam current during the growth process is 60 min / layer, the antimony source beam current is 6 min / layer, the growth rate is 0.019 layer / min, and the growth time is 26 min.

[0050] Example 15

[0051] The method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology according to the present invention comprises the following steps:

[0052] (1) Place the strontium titanate substrate (SrTiO3 (111) wafer) into absolute ethanol, ultrasonically clean it for 15 minutes, pick it out with tweezers after cleaning, gently wipe off the excess ethanol with lint-free paper, then load it into the sample holder, transfer it into the molecular beam epitaxy chamber, and under the ultra-high vacuum condition of 1×10 -9 mbar, heat the strontium titanate substrate to 420°C, keep it warm for 2 h and then degas it, and then heat the substrate to 1000°C, keep it warm for 0.5 h. The surface morphology of the pretreated substrate shows regular steps.

[0053] (2) Using an iron source and an antimony source as evaporation sources, 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 430 °C at a rate of 30 °C / min, the pretreated substrate is 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 is 1:10, the iron source beam current during the growth process is 60 min / layer, the antimony source beam current is 6 min / layer, the growth rate is 0.015 layer / min, and the growth time is 34 min.

[0054] The effects of the high-quality one-dimensional iron-antimony nanowires prepared in Examples 14-15 are the same as those in Example 1.

[0055] The above embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. A method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology, characterized in that, It includes the following steps: (1) After cleaning the strontium titanate substrate, load it into the sample holder, transfer it into the molecular beam epitaxy chamber, and perform pretreatment on the strontium titanate substrate under ultra-high vacuum conditions, so that the surface topography of the pretreated substrate shows regular steps, and the width of the steps is 50 nm to 200 nm; (2) Using iron source and antimony source as evaporation sources, grow iron-antimony nanowires on the pretreated substrate by molecular beam epitaxy growth technology. During the growth process, the evaporation temperature of the iron source is 1170 °C to 1230 °C, the evaporation temperature of the antimony source is 350 °C to 430 °C, the temperature of the pretreated substrate is maintained at 380 °C to 420 °C, the growth rate is 0.015 layer / min to 0.019 layer / min, the growth time is 26 min to 34 min, and the height of the iron-antimony nanowires is 8.03 Å and the width is 2.7 nm.

2. The method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy 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 antimonide nanowires by using molecular beam epitaxy 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; the vacuum is maintained at 5×10 -10 mbar to 1×10 - 9 mbar.

4. The method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology according to claim 3, characterized in that In step (2), the heating rate of the pretreated substrate and the antimony source is 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 antimonide nanowires by using molecular beam epitaxy 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); the iron source beam current during the growth process is 54 min / layer to 66 min / layer, and the antimony source beam current is 5.4 min / layer to 6.6 min / layer.

6. The method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy growth technology according to claim 3, characterized in that, In step (1), the pre-treatment includes: under an ultra-high vacuum condition of 5×10 -10 mbar to 1×10 -9 mbar, heating the strontium titanate substrate to 380°C to 420°C, keeping it warm for 1.5 h to 2.5 h and then degassing it, and then heating the substrate to 800°C to 1000°C and keeping it warm for 0.25 h to 0.75 h.

7. The method for preparing high-quality one-dimensional iron antimonide nanowires by using molecular beam epitaxy 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 antimonide nanowires by using molecular beam epitaxy growth technology according to claim 3, characterized in that In step (1), the cleaning includes: putting the strontium titanate substrate into absolute ethanol, ultrasonically cleaning for 15 minutes, taking it out with tweezers after cleaning, and gently wiping off the excess ethanol with dust-free paper.

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

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