Manganese and tellurium co-doped germanium double-layer quantum dot material, preparation method and application thereof

Abstract

The application provides a manganese-tellurium co-doped germanium double-layer quantum dot material and a preparation method and application thereof, and relates to the technical field of nanometer materials.The application improves the order of the quantum dot by growing a multilayer structure quantum dot, and obtains uniform quantum dots by regulating the thickness of the silicon intermediate layer;firstly, the distribution of the strain of the upper layer (referring to the second manganese-tellurium co-doped germanium quantum dot layer) gradually becomes uniform with the increase of the thickness of the silicon intermediate layer, so the uniformity of the quantum dots is increased;secondly, the quantum dots of the bottom layer (referring to the first manganese-tellurium co-doped germanium quantum dot layer) can produce a tensile strain area on the upper surface of the silicon intermediate layer, and can provide favorable conditions for the nucleation of the upper layer quantum dots.The application solves the problems of the prior art, such as the Curie temperature of the quantum dots being less than room temperature, and the size and density distribution of the prepared quantum dots being non-uniform, by preparing manganese-tellurium co-doped germanium double-layer quantum dots.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and in particular to a manganese and tellurium co-doped germanium double-layer quantum dot material, a preparation method thereof, and an application thereof. Background Art

[0002] Compared with traditional silicon-based semiconductor materials, the natural property of germanium's indirect band gap is conducive to minimizing the scattering of spin-polarized carriers at the interface, thereby reducing the loss of current and spin polarization, and has a sufficiently large spin splitting energy. The low-dimensionality of the dilute magnetic semiconductor structure inhibits the nucleation and growth of the metallic precipitate phase. The resulting quantum confinement effect is conducive to enhancing the exchange coupling between bound holes and localized manganese ions, improving ferromagnetic order. Among them, manganese doping introduces ferromagnetism. The ferromagnetism originates from a hole-mediated process, that is, holes flow around the manganese ions, and through exchange coupling, the manganese magnetic moment is aligned in one direction, thereby generating ferromagnetism. However, existing manganese-doped germanium quantum dots are all single-layer quantum dots, and the ferromagnetism is still relatively low, resulting in the Curie temperature of manganese-doped germanium quantum dots being lower than room temperature.

[0003] In addition, since the growth mode of quantum dots is self-assembly growth, one disadvantage of self-assembly growth of quantum dots is that the randomness of the nucleation position leads to disordered spatial distribution of quantum dots. However, in actual application, quantum dots need to grow in an orderly manner. The orderly grown quantum dots have uniform size and density distribution, which makes the device performance stable when preparing devices such as spin field effect transistors, which is conducive to the effective use of the devices. In addition, the orderly grown quantum dots are conducive to further improving ferromagnetism. Summary of the Invention

[0004] The purpose of the present invention is to provide a manganese-tellurium co-doped germanium double-layer quantum dot material and its preparation method and application. The manganese-tellurium co-doped germanium double-layer quantum dot material provided by the present invention can improve the orderliness of quantum dots and solve the technical problems of uneven growth size and low Curie temperature of single-layer quantum dots.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a manganese-tellurium co-doped germanium double-layer quantum dot material, comprising a silicon substrate, a silicon buffer layer, a first manganese-tellurium co-doped germanium quantum dot layer, a silicon intermediate layer and a second manganese-tellurium co-doped germanium quantum dot layer stacked in sequence; the thickness of the silicon intermediate layer is 10 to 40 nm.

[0007] Preferably, the thickness of the silicon buffer layer is 30-60 nm.

[0008] Preferably, the thickness of the first manganese-tellurium co-doped germanium quantum dot layer and the second manganese-tellurium co-doped germanium quantum dot layer are independently 3 to 8 nm.

[0009] Preferably, the silicon substrate is p-type silicon.

[0010] Preferably, the size of the manganese tellurium co-doped germanium quantum dots in the first manganese tellurium co-doped germanium quantum dot layer and the second manganese tellurium co-doped germanium quantum dot layer is 10 to 40 nm.

[0011] The present invention provides a method for preparing the manganese and tellurium co-doped germanium double-layer quantum dot material described in the above scheme, comprising the following steps:

[0012] A silicon buffer layer, a first manganese-tellurium co-doped germanium quantum dot layer, a silicon intermediate layer and a second manganese-tellurium co-doped germanium quantum dot layer are sequentially deposited on the surface of a silicon substrate by ion beam sputtering, and annealed to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material; the deposition thickness of the silicon intermediate layer is 10 to 40 nm.

[0013] Preferably, the growth temperatures of the deposited silicon buffer layer, the first manganese and tellurium co-doped germanium quantum dot layer, the silicon intermediate layer and the second manganese and tellurium co-doped germanium quantum dot layer are independently 550-800°C.

[0014] Preferably, the annealing temperature is 380-540° C., and the holding time is 30-50 minutes.

[0015] Preferably, when depositing the first manganese-tellurium co-doped germanium quantum dot layer and the second manganese-tellurium co-doped germanium quantum dot layer, a manganese sheet and a tellurium sheet are attached to a germanium target for co-sputtering.

[0016] The present invention provides the use of the manganese and tellurium co-doped germanium double-layer quantum dot material described in the above scheme or the manganese and tellurium co-doped germanium double-layer quantum dot material prepared by the preparation method described in the above scheme in a spin field effect transistor.

[0017] The present invention provides a manganese-tellurium co-doped germanium double-layer quantum dot material, comprising a silicon substrate, a silicon buffer layer, a first manganese-tellurium co-doped germanium quantum dot layer, a silicon intermediate layer, and a second manganese-tellurium co-doped germanium quantum dot layer, stacked in sequence; the silicon intermediate layer has a thickness of 10 to 40 nm. By doping the manganese-germanium quantum dots with tellurium, the quantum dots are transformed into Rashba polar semiconductors, increasing the sample's hole concentration and enhancing the quantum dots' ferromagnetism, resulting in quantum dots with a Curie temperature exceeding room temperature.

[0018] Furthermore, the present invention improves the orderliness of quantum dots by growing a multilayer structure of quantum dots and obtains uniform quantum dots by regulating the thickness of the silicon interlayer: first, the strain distribution of the upper layer (referring to the second manganese-tellurium co-doped germanium quantum dot layer) gradually becomes more uniform as the thickness of the silicon interlayer increases, thereby increasing the uniformity of the quantum dots; second, the quantum dots in the bottom layer (referring to the first manganese-tellurium co-doped germanium quantum dot layer) will produce a tensile strain region on the upper surface of the silicon interlayer, which can provide favorable conditions for the nucleation of the quantum dots in the upper layer. By preparing a double-layer of manganese-tellurium co-doped germanium quantum dots, the present invention solves the problems of quantum dots in the prior art, such as the Curie temperature of quantum dots being below room temperature and the uneven size and density distribution of the prepared quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Examples 1 to 5;

[0020] Figure 2 This is an atomic force microscope image of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 1;

[0021] Figure 3 This is the Raman image of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 1 under 532nm excitation;

[0022] Figure 4 This is an atomic force microscope image of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 2;

[0023] Figure 5 This is the Raman image of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 2 under 532nm excitation;

[0024] Figure 6 This is an atomic force microscope image of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 3;

[0025] Figure 7 This is the hysteresis loop diagram of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 3 at 10K;

[0026] Figure 8 This is the hysteresis loop diagram of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 3 at 300K;

[0027] Figure 9 This is the hysteresis loop diagram of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 4 at 10K;

[0028] Figure 10 This is the hysteresis loop diagram of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 4 at 300K;

[0029] Figure 11This is a diagram showing the relationship between the field-cooled magnetic moment and temperature of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 5;

[0030] Figure 12 This is the Curie-Weiss fitting diagram of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 5;

[0031] Figure 13 This is a diagram showing the relationship between the field-cooled magnetic moment and temperature of the manganese and tellurium co-doped germanium single-layer quantum dot material prepared in Comparative Example 1;

[0032] Figure 14 This is the Curie-Weiss fitting diagram of the manganese and tellurium co-doped germanium single-layer quantum dot material prepared in Comparative Example 1;

[0033] Figure 15 This is an atomic force microscope image of the manganese and tellurium co-doped germanium single-layer quantum dot material prepared in Comparative Example 1;

[0034] Figure 16 This is an atomic force microscope image of the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Comparative Example 2. DETAILED DESCRIPTION

[0035] The present invention provides a manganese-tellurium co-doped germanium double-layer quantum dot material, comprising a silicon substrate, a silicon buffer layer, a first manganese-tellurium co-doped germanium quantum dot layer, a silicon intermediate layer and a second manganese-tellurium co-doped germanium quantum dot layer stacked in sequence; the thickness of the silicon intermediate layer is 10 to 40 nm.

[0036] The manganese-tellurium co-doped germanium double-layer quantum dot material provided herein includes a silicon substrate. In the present invention, the silicon substrate is preferably p-type silicon. The use of p-type silicon increases the hole concentration, enhances the exchange coupling between holes and manganese, and improves ferromagnetism. The present invention does not have any specific requirements for the thickness of the silicon substrate; thicknesses known in the art can be used.

[0037] The manganese-tellurium co-doped germanium double-layer quantum dot material provided herein includes a silicon buffer layer attached to the surface of the silicon substrate. In the present invention, the thickness of the silicon buffer layer is preferably 30 to 60 nm, more preferably 35 to 55 nm, and even more preferably 40 to 50 nm. The silicon buffer layer improves the surface flatness of the silicon substrate and reduces defects and impurity concentrations at the interface between the epitaxial layer and the silicon substrate.

[0038] The manganese tellurium co-doped germanium double-layer quantum dot material provided by the present invention includes a first manganese tellurium co-doped germanium quantum dot layer attached to the surface of the silicon buffer layer. The thickness of the first manganese tellurium co-doped germanium quantum dot layer is preferably 3 to 8 nm, more preferably 4 to 7 nm, and further preferably 5 to 6 nm.

[0039] The manganese telluride co-doped germanium double-layer quantum dot material provided by the present invention includes a silicon intermediate layer attached to the surface of the first manganese telluride co-doped germanium quantum dot layer. In the present invention, the thickness of the silicon intermediate layer is 10 to 40 nm, preferably 15 to 35 nm, and more preferably 20 to 30 nm. The present invention improves the orderliness of quantum dots by growing multi-layer quantum dots and obtains uniform quantum dots by regulating the thickness of the silicon intermediate layer: first, the strain distribution of the upper layer (referring to the second manganese telluride co-doped germanium quantum dot layer) gradually becomes uniform as the thickness of the silicon intermediate layer increases, so the uniformity of the quantum dots increases; second, the quantum dots in the bottom layer (referring to the first manganese telluride co-doped germanium quantum dot layer) will produce a tensile strain area on the upper surface of the silicon intermediate layer, which can provide favorable conditions for the nucleation of the upper quantum dots. The present invention solves the problem of quantum dots having a Curie temperature lower than room temperature and uneven size and density distribution of the prepared quantum dots in the prior art by preparing manganese telluride co-doped germanium double-layer quantum dots.

[0040] The manganese tellurium co-doped germanium double-layer quantum dot material provided by the present invention includes a second manganese tellurium co-doped germanium quantum dot layer attached to the surface of the silicon intermediate layer. In the present invention, the thickness of the second manganese tellurium co-doped germanium quantum dot layer is preferably 3 to 8 nm, more preferably 4 to 7 nm, and further preferably 5 to 6 nm. In the present invention, the size of the second manganese tellurium co-doped germanium quantum dot in the second manganese tellurium co-doped germanium quantum dot layer is preferably 10 to 40 nm, and the density is preferably 3.0 to 4.5×10 10 pieces / cm -2 In an embodiment of the present invention, the size of the manganese-tellurium co-doped germanium quantum dots is specifically 31nm, 17nm, or 26nm. The present invention transforms the manganese-germanium quantum dots into Rashba polar semiconductors by doping them with tellurium, thereby increasing the hole concentration of the sample and the ferromagnetism of the quantum dots, thereby obtaining quantum dots with a Curie temperature exceeding room temperature.

[0041] The present invention provides a method for preparing the manganese and tellurium co-doped germanium double-layer quantum dot material described in the above scheme, comprising the following steps:

[0042] A silicon buffer layer, a first manganese-tellurium co-doped germanium quantum dot layer, a silicon intermediate layer and a second manganese-tellurium co-doped germanium quantum dot layer are sequentially deposited on the surface of a silicon substrate by ion beam sputtering, and annealed to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material; the deposition thickness of the silicon intermediate layer is 10 to 40 nm.

[0043] Before deposition, the present invention preferably cleans the silicon substrate. The present invention has no special requirements for the size of the silicon substrate, and those skilled in the art can adjust it according to actual needs. In the embodiment of the present invention, the silicon substrate is square and has a size of 1×1 cm to 3×3 cm.

[0044] In the present invention, the target material used for depositing the silicon buffer layer and silicon intermediate layer is preferably a silicon target. When depositing the first and second manganese-tellurium co-doped germanium quantum dot layers, a manganese sheet and a tellurium sheet are preferably attached to a germanium target for co-sputtering. In the present invention, the manganese sheet, tellurium sheet, and germanium target are preferably square. Since the target material is mounted in a square position during ion beam loading, the target material is designed to fit the target position. In the present invention, the side lengths of the manganese and tellurium sheets are preferably 0.5 to 2 cm; the side length of the germanium target is preferably 4 to 8 cm. The manganese and tellurium sheets should be attached as close to the center of the target as possible. The present invention does not require the number of manganese and tellurium sheets. By adjusting their position on the germanium target and increasing or decreasing the number of manganese and tellurium sheets, the composition of manganese, tellurium, and germanium can be adjusted. In the present invention, the thickness of the manganese and tellurium sheets is preferably 3 to 5 cm.

[0045] In the present invention, the growth temperatures for the deposited silicon buffer layer, the first manganese-telluride co-doped germanium quantum dot layer, the silicon intermediate layer, and the second manganese-telluride co-doped germanium quantum dot layer are independently preferably 550-800°C, more preferably 600-750°C. The present invention does not have any particular requirements for the vacuum level during the deposition of each layer; a deposition vacuum level well known in the art can be employed. After each layer is deposited, the temperature is preferably maintained for 10-30 minutes.

[0046] After the second manganese and tellurium co-doped germanium quantum dot layer is deposited and kept warm, the present invention anneals the obtained material to obtain a manganese and tellurium co-doped germanium double-layer quantum dot material.

[0047] In the present invention, the annealing temperature is preferably 380-540°C, more preferably 400-500°C, and even more preferably 420-480°C; the holding time is preferably 30-50 minutes, more preferably 35-45 minutes. Annealing is used to improve the crystallinity of quantum dots, reduce defects and dislocations, and thus increase the Curie temperature of the quantum dots.

[0048] The present invention provides the use of the manganese and tellurium co-doped germanium double-layer quantum dot material described in the above scheme or the manganese and tellurium co-doped germanium double-layer quantum dot material prepared by the preparation method described in the above scheme in a spin field effect transistor.

[0049] The manganese and tellurium co-doped germanium double-layer quantum dot material provided by the present invention, its preparation method and application are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0050] Example 1

[0051] (1) Cut the manganese and tellurium sheets into 9 and 5 sheets (0.5 × 0.5 cm) pieces, respectively, and then attach them to a germanium target (4 × 4 cm) around the center of the target. Cleaned p-type silicon (1 × 1 cm) is used as the substrate for growing quantum dots.

[0052] (2) placing the target material obtained in step (1) and the cleaned p-type silicon into an ion beam sputtering device and setting the sputtering temperature to 550°C;

[0053] (3) depositing a silicon buffer layer with a thickness of 30 nm on the silicon substrate obtained in step (2), and keeping the layer warm for 20 minutes after deposition;

[0054] (4) growing a first manganese-germanium-telluride quantum dot layer on the silicon buffer layer obtained in step (3) with a thickness of 3 nm, and keeping the layer warm for 10 minutes after deposition;

[0055] (5) growing a silicon intermediate layer with a thickness of 10 nm on the first manganese-tellurium-doped germanium quantum dot layer obtained in step (4), and keeping the layer warm for 10 minutes after deposition;

[0056] (6) growing a second manganese-germanium-telluride quantum dot layer on the silicon intermediate layer obtained in step (5) with a thickness of 3 nm, and keeping the layer warm for 10 minutes after deposition;

[0057] (7) Annealing the material obtained in step (6) at a temperature of 380° C. for 40 minutes to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material.

[0058] Example 2

[0059] (1) Cut the manganese and tellurium sheets into slices (0.5 × 0.5 cm), with 13 manganese and 8 tellurium sheets attached, respectively. These sheets were then attached to a germanium target (5 × 5 cm) around its center. Cleaned p-type silicon (1 × 1 cm) was used as the substrate for growing quantum dots.

[0060] (2) placing the target material obtained in step (1) and the cleaned p-type silicon into an ion beam sputtering device and setting the sputtering temperature to 650°C;

[0061] (3) depositing a silicon buffer layer with a thickness of 40 nm on the silicon substrate obtained in step (2), and keeping the layer warm for 20 minutes after deposition;

[0062] (4) growing a first manganese-germanium-telluride quantum dot layer on the silicon buffer layer obtained in step (3) with a thickness of 4 nm, and keeping the layer warm for 15 minutes after deposition;

[0063] (5) growing a silicon intermediate layer with a thickness of 10 nm on the manganese-tellurium-doped germanium quantum dot layer obtained in step (4), and keeping the temperature for 20 minutes after deposition;

[0064] (6) growing a second manganese-germanium-telluride quantum dot layer on the silicon intermediate layer obtained in step (5) with a thickness of 4 nm, and keeping the layer warm for 15 minutes after deposition;

[0065] (7) Annealing the material obtained in step (6) at a temperature of 420° C. for 40 minutes to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material.

[0066] Example 3

[0067] (1) Cut the manganese and tellurium sheets into slices (1 × 1 cm), with 15 manganese and 10 tellurium sheets attached to the target. These slices are then placed around the center of the target and attached to a germanium target (6 × 6 cm). Cleaned p-type silicon (1.5 × 1.5 cm) is used as the substrate for growing quantum dots.

[0068] (2) placing the target material obtained in step (1) and the cleaned p-type silicon into an ion beam sputtering device and setting the sputtering temperature to 750°C;

[0069] (3) depositing a silicon buffer layer with a thickness of 50 nm on the silicon substrate obtained in step (2), and keeping the layer warm for 20 minutes after deposition;

[0070] (4) growing a first manganese-germanium-telluride quantum dot layer on the silicon buffer layer obtained in step (3) with a thickness of 6 nm, and keeping the layer warm for 10 minutes after deposition;

[0071] (5) growing a silicon intermediate layer with a thickness of 20 nm on the first manganese-tellurium-doped germanium quantum dot layer obtained in step (4), and keeping the temperature for 20 minutes after deposition;

[0072] (6) growing a second manganese-germanium-telluride quantum dot layer on the silicon intermediate layer obtained in step (5) with a thickness of 6 nm, and keeping the layer warm for 10 minutes after deposition;

[0073] (7) Annealing the material obtained in step (6) at a temperature of 460° C. for 50 minutes to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material.

[0074] Example 4

[0075] (1) Cut the manganese and tellurium sheets into 1×1 cm sheets, with 18 and 13 sheets respectively. These sheets are then attached to a germanium target (7×7 cm) around its center. Cleaned p-type silicon (2×2 cm) is used as the substrate for growing quantum dots.

[0076] (2) placing the target material obtained in step (1) and the cleaned p-type silicon into an ion beam sputtering device and setting the sputtering temperature to 750°C;

[0077] (3) depositing a silicon buffer layer with a thickness of 50 nm on the silicon substrate obtained in step (2), and keeping the layer warm for 30 minutes after deposition;

[0078] (4) growing a first manganese-germanium-telluride quantum dot layer on the silicon buffer layer obtained in step (3) with a thickness of 7 nanometers, and keeping the layer warm for 15 minutes after deposition;

[0079] (5) growing a silicon intermediate layer with a thickness of 40 nm on the first manganese-tellurium-doped germanium quantum dots obtained in step (4), and keeping the layer warm for 20 minutes after deposition;

[0080] (6) growing a second manganese-germanium-telluride quantum dot layer on the silicon intermediate layer obtained in step (5) with a thickness of 7 nanometers, and keeping the layer warm for 15 minutes after deposition;

[0081] (7) Annealing the material obtained in step (6) at a temperature of 500° C. for 30 minutes to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material.

[0082] Example 5

[0083] (1) Cut the manganese and tellurium sheets into 1×1 cm pieces, with 18 and 15 pieces respectively. Then, they were attached to a germanium target (8×8 cm) around the center of the target. Cleaned p-type silicon (3×3 cm) was used as the substrate for growing quantum dots.

[0084] (2) placing the target material obtained in step (1) and the cleaned p-type silicon as a substrate into an ion beam sputtering device, and setting the sputtering temperature to 800° C.;

[0085] (3) depositing a silicon buffer layer with a thickness of 60 nm on the silicon substrate obtained in step (2), and keeping the layer warm for 20 minutes after deposition;

[0086] (4) growing a first manganese-germanium-telluride quantum dot layer on the silicon buffer layer obtained in step (3) with a thickness of 8 nm, and keeping the layer warm for 20 minutes after deposition;

[0087] (5) growing a silicon intermediate layer with a thickness of 30 nm on the first manganese-tellurium-doped germanium quantum dot layer obtained in step (4), and keeping the layer warm for 30 minutes after deposition;

[0088] (6) growing a second manganese-germanium-telluride quantum dot layer on the silicon intermediate layer obtained in step (5) with a thickness of 8 nm, and keeping the layer warm for 20 minutes after deposition;

[0089] (7) Annealing the material obtained in step (6) at a temperature of 540° C. for 40 minutes to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material.

[0090] Comparative Example 1

[0091] (1) Cut the manganese and tellurium sheets into 1×cm slices, with 18 and 15 slices respectively, and then paste them onto a germanium target (8×8cm). Cleaned p-type silicon (3×3cm) is used as the substrate for growing quantum dots.

[0092] (2) placing the target material obtained in step (1) and the cleaned p-type silicon as a substrate into an ion beam sputtering device, and setting the sputtering temperature to 800° C.;

[0093] (3) depositing a silicon buffer layer on the silicon substrate obtained in step (2) with a thickness of 60 nm and holding the layer for 20 minutes after deposition;

[0094] (4) growing a manganese germanium telluride quantum dot layer on the silicon buffer layer obtained in step (3) with a thickness of 8 nm, and keeping the layer warm for 20 minutes after deposition;

[0095] (5) Annealing the manganese and tellurium co-doped germanium quantum dots obtained in step (4) at a temperature of 540° C. for 40 minutes to obtain a single-layer manganese and tellurium co-doped germanium quantum dot material.

[0096] Comparative Example 2

[0097] (1) Cut the manganese and tellurium sheets into slices (0.5 × 0.5 cm), with 13 manganese and 8 tellurium sheets attached, respectively. These sheets were then attached to a germanium target (5 × 5 cm) around its center. Cleaned p-type silicon (1 × 1 cm) was used as the substrate for growing quantum dots.

[0098] (2) placing the target material obtained in step (1) and the cleaned p-type silicon into an ion beam sputtering device and setting the sputtering temperature to 650°C;

[0099] (3) depositing a silicon buffer layer with a thickness of 40 nm on the silicon substrate obtained in step (2), and keeping the layer warm for 20 minutes after deposition;

[0100] (4) growing a first manganese-germanium-telluride quantum dot layer on the silicon buffer layer obtained in step (3) with a thickness of 4 nm, and keeping the layer warm for 15 minutes after deposition;

[0101] (5) growing a silicon intermediate layer with a thickness of 5 nm on the manganese-tellurium-doped germanium quantum dot layer obtained in step (4), and keeping the temperature for 20 minutes after deposition;

[0102] (6) growing a second manganese-germanium-telluride quantum dot layer on the silicon intermediate layer obtained in step (5) with a thickness of 4 nm, and keeping the layer warm for 15 minutes after deposition;

[0103] (7) Annealing the material obtained in step (6) at a temperature of 420° C. for 40 minutes to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material.

[0104] Performance Testing

[0105] 1. Figure 1 Schematic diagram of the structure of the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Examples 1 to 5; Atomic force microscopy was used to characterize the manganese and tellurium co-doped germanium double-layer quantum dot material prepared in Example 1 at room temperature, and the surface morphology obtained is shown in FIG. Figure 2 As shown; under 532nm excitation light, the Raman pattern of the manganese telluride co-doped germanium double-layer quantum dot material is as follows Figure 3 As shown. Figures 2-3 It can be seen that the size of the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Example 1 is 31 nm, and the density reaches 3.3×10 10 pieces / cm -2 Under 532nm laser excitation, the Ge-Ge peak (standard peak 300cm -1 ) shifts to higher wavenumbers, indicating the presence of stronger compressive strain in the Mn / Te co-doped Ge bilayer quantum dots.

[0106] 2. Using atomic force microscopy, the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Example 2 were characterized at room temperature. The surface morphology obtained is shown in FIG. Figure 4 As shown; under 532nm excitation light, the Raman image of the manganese telluride co-doped germanium double-layer quantum dots is as follows Figure 5 As shown. Figures 4-5 It can be seen that the size of the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Example 2 is 17 nm, and the density reaches 3.7×10 10 pieces / cm -2 Under 532nm laser excitation, the Ge-Ge peak (standard peak 300cm -1 ) and Ge-Te peaks shift to higher wavenumbers, indicating that there is a stronger compressive strain in the manganese-telluride co-doped germanium double-layer quantum dots. The intensity of the Ge-Te peak increases with the increase of the number of layers, indicating that the crystallinity of the manganese-telluride co-doped germanium double-layer quantum dots is enhanced.

[0107] 3. The Mn / Te co-doped Ge double-layer quantum dot material prepared in Example 3 was characterized at room temperature using an atomic force microscope. The surface morphology obtained is shown in FIG. Figure 6 As shown; the magnetic measurement is carried out in a physical property measurement system. The hysteresis loop of the manganese-tellurium co-doped germanium double-layer quantum dot material at 10K is shown as Figure 7 As shown, at 300K, the hysteresis loop is as follows Figure 8 As shown. Figures 6-8 It can be seen that the size of the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Example 3 is 26 nm, and the density reaches 4.2×10 10 pieces / cm -2, indicating that the density of the MnTe co-doped Ge double-layer quantum dots increases with the increase of growth temperature, and the uniformity of the quantum dots improves while the crystallinity also increases. This performance highly matches the requirements of new spintronic materials in practical applications. At 10K, the saturation magnetic moment of the MnTe co-doped Ge double-layer quantum dots reaches 5.3×10 -5 emu / mm 2 , the residual magnetic moment reaches 1.41×10 -5 emu / mm 2 At 300K, the saturation magnetic moment reaches 5.16×10 -5 emu / mm 2 , the residual magnetic moment reaches 1.36×10 -5 emu / mm 2 The manganese-tellurium co-doped germanium double-layer quantum dots have excellent ferromagnetic properties.

[0108] 4. The magnetic measurement of the manganese-tellurium co-doped germanium double-layer quantum dot material prepared in Example 4 was carried out in a physical property measurement system. The hysteresis loop of the manganese-tellurium co-doped germanium double-layer quantum dot material measured at 10K is as follows: Figure 9 As shown, the hysteresis loop measured at 300K is as follows Figure 10 As shown. Figures 9-10 It can be seen that the saturation magnetic moment of the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Example 4 reaches 2.17×10 -5 emu / mm 2 , the residual magnetic moment reaches 0.75×10 -5 emu / mm 2 At 300K, the saturation magnetic moment of the MnTe co-doped Ge double-layer quantum dots reaches 1.74×10 -5 emu / mm 2 , the residual magnetic moment reaches 0.38×10 -5 emu / mm 2 , with excellent magnetic properties, indicating that the Curie temperature of the manganese telluride co-doped germanium double-layer quantum dots exceeds 300K and they still have ferromagnetism at room temperature.

[0109] 5. The magnetic measurement of the manganese-tellurium co-doped germanium double-layer quantum dot material prepared in Example 5 was carried out in a physical property measurement system. The relationship between the field cooling magnetic moment and temperature of the manganese-tellurium co-doped germanium double-layer quantum dot is shown in the figure below. Figure 11 As shown, the Curie-Weiss fitting diagram is as follows Figure 12 shown by Figures 11-12 It can be seen that the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Example 5 transform from ferromagnetism to paramagnetism after 300K, and the Curie temperature is as high as 323K, and a magnetic functional material that operates stably at room temperature is obtained.

[0110] 6. The magnetic measurement of the manganese and tellurium co-doped germanium single-layer quantum dots prepared in Comparative Example 1 was carried out in a physical property measurement system. The relationship between the field cooling magnetic moment and temperature of the manganese and tellurium co-doped germanium single-layer quantum dots is shown in the figure below. Figure 13 As shown, the Curie-Weiss fitting diagram is as follows Figure 14 shown by Figures 13-14 It can be seen that the manganese and tellurium co-doped germanium single-layer quantum dots prepared in Comparative Example 1 change from ferromagnetism to paramagnetism after 200K, and the Curie temperature is only 220K. It does not reach a Curie temperature above room temperature, and cannot obtain a magnetic functional material that can operate stably at room temperature. The manganese and tellurium co-doped germanium single-layer quantum dots prepared in Comparative Example 1 were characterized at room temperature using an atomic force microscope. The surface morphology obtained is shown in the figure below. Figure 15 As shown, compared with the double-layer quantum dots, the manganese telluride co-doped germanium single-layer quantum dots prepared in Comparative Example 1 are relatively sparse, with a quantum dot density of 1.8×10 10 pieces / cm -2 In contrast, the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Example 5 transition from ferromagnetism to paramagnetism after 300K, with a Curie temperature as high as 323K, achieving a magnetic functional material that operates stably at room temperature.

[0111] 7. Atomic force microscopy was used to characterize the manganese and tellurium co-doped germanium double-layer quantum dots prepared in Comparative Example 2 at room temperature. The surface morphology obtained is shown in FIG. Figure 16 As shown, compared with the double-layer quantum dots obtained by growing a 10nm silicon intermediate layer in Example 2, the single-layer quantum dots of manganese and tellurium co-doped with 5nm silicon intermediate layer prepared in Comparative Example 2 are relatively sparse, with a density of 0.3×10 10 pieces / cm -2 It was observed that the size and density distribution of the manganese and tellurium co-doped germanium double-layer quantum dots obtained by this preparation method were uneven.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A manganese-tellurium co-doped germanium double-layer quantum dot material, comprising a silicon substrate, a silicon buffer layer, a first manganese-tellurium co-doped germanium quantum dot layer, a silicon intermediate layer, and a second manganese-tellurium co-doped germanium quantum dot layer stacked in sequence; the thickness of the silicon intermediate layer is 10 to 40 nm.

2. The manganese-tellurium co-doped germanium double-layer quantum dot material according to claim 1, characterized in that: The thickness of the silicon buffer layer is 30-60 nm.

3. The manganese-tellurium co-doped germanium double-layer quantum dot material according to claim 1, characterized in that: The thickness of the first manganese and tellurium co-doped germanium quantum dot layer and the second manganese and tellurium co-doped germanium quantum dot layer are independently 3 to 8 nm.

4. The manganese-tellurium co-doped germanium double-layer quantum dot material according to claim 1, characterized in that: The silicon substrate is p-type silicon.

5. The manganese-tellurium co-doped germanium double-layer quantum dot material according to claim 1, characterized in that: The size of the manganese and tellurium co-doped germanium quantum dots in the first manganese and tellurium co-doped germanium quantum dot layer and the second manganese and tellurium co-doped germanium quantum dot layer is 10 to 40 nm.

6. The method for preparing the manganese and tellurium co-doped germanium double-layer quantum dot material according to any one of claims 1 to 5, comprising the following steps: A silicon buffer layer, a first manganese-tellurium co-doped germanium quantum dot layer, a silicon intermediate layer and a second manganese-tellurium co-doped germanium quantum dot layer are sequentially deposited on the surface of a silicon substrate by ion beam sputtering, and annealed to obtain a manganese-tellurium co-doped germanium double-layer quantum dot material; the deposition thickness of the silicon intermediate layer is 10 to 40 nm.

7. The preparation method according to claim 6, characterized in that The growth temperatures of the deposited silicon buffer layer, the first manganese and tellurium co-doped germanium quantum dot layer, the silicon intermediate layer and the second manganese and tellurium co-doped germanium quantum dot layer are independently 550-800°C.

8. The preparation method according to claim 6, characterized in that The annealing temperature is 380-540° C., and the holding time is 30-50 minutes.

9. The preparation method according to claim 6, characterized in that When depositing the first manganese and tellurium co-doped germanium quantum dot layer and the second manganese and tellurium co-doped germanium quantum dot layer, the manganese sheet and the tellurium sheet are attached to a germanium target for co-sputtering.

10. Use of the manganese telluride co-doped germanium double-layer quantum dot material according to any one of claims 1 to 5 or the manganese telluride co-doped germanium double-layer quantum dot material prepared by the preparation method according to any one of claims 6 to 9 in a spin field effect transistor.

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