A two-dimensional organic-inorganic heterojunction capable of generating interlayer excitons and a preparation method thereof

Abstract

The application discloses a two-dimensional organic-inorganic heterojunction capable of generating interlayer excitons and a preparation method thereof, and the preparation steps comprise the following steps: S1, preparing double-layer pentacene crystals by a physical vapor phase transmission method; S2, preparing single-layer tungsten selenide crystals by a mechanical exfoliation method or a chemical vapor deposition method; and S3, transferring the single-layer tungsten selenide to the double-layer pentacene by a dry transfer method to prepare a single-layer tungsten selenide / double-layer pentacene heterojunction. The two-dimensional single-layer tungsten selenide / double-layer pentacene heterojunction capable of generating interlayer excitons is prepared by designing a band arrangement and adopting a dry transfer process.

Description

Technical Field

[0001] This invention belongs to the field of nano-semiconductor devices, specifically relating to a two-dimensional organic-inorganic heterojunction capable of generating interlayer excitons and its preparation method. Background Technology

[0002] In the post-Moore's Law era, optoelectronic devices integrating computing, storage, communication, and information processing are constantly evolving towards faster speeds, smaller sizes, lower power consumption, lower prices, and more comprehensive functions. However, traditional silicon-based semiconductors are approaching the limits of the material itself. Silicon-based microelectronics technology faces challenges such as short-channel effects, quantum tunneling effects, and power losses. Therefore, two-dimensional semiconductor materials, as a complement to silicon-based semiconductors, are gradually gaining popularity in scientific research and industry.

[0003] In two-dimensional semiconductor materials, the combination of a single atomic layer of transition metal chalcogenide (TMD) with other two-dimensional materials can generate a rich array of exciton physics phenomena, such as dark excitons, interlayer excitons, and multiexciton complexes, possessing enormous potential for development in quantum information applications such as exciton condensation and single-photon excitation. Furthermore, organic crystals offer advantages such as a vast material library, clear interfaces, good compatibility with TMDs, high binding energy, high exciton density, and ultrafast charge transfer processes at organic / inorganic interfaces. More interestingly, organic crystals exhibit thickness-dependent optical and transport properties at the two-dimensional scale. Therefore, two-dimensional organic-inorganic heterojunctions have become an ideal platform for studying novel physical phenomena, including interlayer excitons / triexcitons. Currently, two-dimensional monolayer tungsten selenide (WSe2) / bilayer pentacene heterojunctions have been reported to exhibit type II interlayer triexcitons, which are formed by the binding of intralayer excitons with charges from different layers. However, interlayer excitons have not been observed in this heterojunction. Summary of the Invention

[0004] The purpose of this invention is to provide a two-dimensional organic-inorganic heterostructure that can generate interlayer excitons, prepared by the above method.

[0005] Another objective of this invention is to provide a method for preparing two-dimensional organic-inorganic heterostructures capable of generating interlayer excitons.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] On one hand, the present invention provides a method for preparing a two-dimensional organic-inorganic heterostructure capable of generating interlayer excitons, comprising the following steps:

[0008] S1. Preparation of bilayer pentacene crystals by physical vapor transport method;

[0009] S2. Preparation of monolayer tungsten selenide crystals by mechanical exfoliation or chemical vapor deposition;

[0010] S3. A monolayer tungsten selenide / bilayer pentane heterojunction was prepared by transferring a monolayer tungsten selenide onto a bilayer pentane using a dry transfer method.

[0011] Preferably, the specific steps for preparing bilayer pentacene crystals using the physical vapor transport method in step S1 are as follows: A 20 nm thick few-layer boron nitride is mechanically peeled off and placed onto the growth substrate; the pentacene crystal powder is placed at the center of the tube furnace tube, and the growth substrate with boron nitride is placed 13-15 cm downstream of it; the furnace tube is evacuated to 1 × 10⁻⁶ ppm. -4 After being placed in a vacuum environment, the furnace was heated to 130°C to grow pentaphenyl crystals for 30 minutes. The sample was then allowed to cool naturally to room temperature under the same vacuum. The number of layers was determined to find the desired bilayer pentaphenyl.

[0012] Preferably, the growth substrate is a SiO2 / Si wafer.

[0013] Preferably, the dry transfer in step S3 is a PDMS-assisted transfer method.

[0014] On the other hand, the present invention provides a two-dimensional organic-inorganic heterostructure capable of generating interlayer excitons prepared by the above method.

[0015] Compared with existing technologies, this invention designs the band arrangement and uses a dry transfer process to prepare a two-dimensional monolayer tungsten selenide / bilayer pentane heterojunction that can generate interlayer excitons. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the heterojunction structure of the present invention; in the figure, 1-silicon wafer layer; 2-silicon dioxide layer; 3-few-layer boron nitride; 4-bilayer pentacene; 5-monolayer tungsten selenide;

[0017] Figure 2 An optical microscope image of a heterojunction prepared in Example 1 of this invention;

[0018] Figure 3 These are atomic force microscopy images of boron nitride thin films with different numbers of pentacene layers prepared in Example 1 of this invention;

[0019] Figure 4 Raman spectroscopy testing of products related to the preparation process in Example 1 of this invention;

[0020] Figure 5 The photoluminescence spectrum of the heterojunction prepared in Example 1 of this invention at a low temperature of 83K. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Example 1

[0023] A two-dimensional organic-inorganic heterostructure capable of generating interlayer excitons is prepared by the following steps:

[0024] S1. Preparation of bilayer pentane crystals by physical vapor transport method: SiO2 / Si (where SiO2 is 285 nm thick) is selected as the growth substrate (e.g., Figure 1 The silicon wafer layer 1 and silicon dioxide layer 2 shown are used to mechanically peel off a 20nm thick few-layer boron nitride 3 onto the growth substrate; pentacene crystal powder is placed in the center of the tube furnace tube, and the growth substrate with boron nitride is placed 14cm downstream of it; the furnace tube is evacuated to 1×10⁻⁶. -4 After creating a vacuum environment of Pa, the furnace was heated to 130°C to grow pentacene crystals for 30 min. The sample was then allowed to cool naturally to room temperature under the same vacuum. The number of layers was determined using an optical microscope, AFM, PL, and Raman spectrometer to find the desired bilayer pentacene 4.

[0025] S2. Obtaining monolayer WSe2 crystals: Tungsten selenide crystals were removed by mechanical exfoliation combined with purchased PDMS, and then monolayer tungsten selenide 5 crystals remaining on the PDMS were searched.

[0026] S3. Dry transfer: Using a transfer platform, a single layer of tungsten selenide 5 and a double layer of pentacene 4 on PDMS are bonded together for 2 hours; then the PDMS is lifted, and the single layer of tungsten selenide 5 and the double layer of pentacene 4 are combined to form an organic-inorganic heterojunction.

[0027] The heterojunction quality and interlayer exciton emission intensity were analyzed by using optical microscopy and photoluminescence spectroscopy.

[0028] Figure 2 Optical microscope images of the heterojunction prepared in Example 1; showing separate bilayer pentanesene (2LPEN), separate monolayer tungsten selenide (1L WSe2), and monolayer tungsten selenide / bilayer pentanesene heterojunction regions (HS represents the heterojunction region).

[0029] Figure 3 The images are atomic force microscopy images of boron nitride thin films with different numbers of pentanes prepared in Example 1. The images show that the thickness between the two layers is about 1.5 nm, which is consistent with the thickness difference between a single layer and a double layer.

[0030] Figure 4 Raman spectroscopy tests were performed on the products related to the preparation process of Example 1. Figure 4 a represents the measured Raman spectrum of a single-layer WSe2, which is consistent with previous reports. Figure 4 b is the measured Raman spectrum of the bilayer pentacene. Figure 4 c represents the measured Raman spectrum of the heterostructure. Figure 4 d is Figure 4 The Raman spectrum of the dotted rectangular region in c represents the bilayer pentacene and Figure 4 b is consistent with the double-layered pentabenzene.

[0031] Figure 5 The photoluminescence spectrum of the heterojunction prepared in Example 1 at a low temperature of 83K is shown. It can be found that compared with the monolayer tungsten selenide and the bilayer pentane, the heterojunction region (the part where the monolayer tungsten selenide and the bilayer pentane are combined) has two emission peaks in the range of ~760-950nm, which represent the emission of interlayer excitons.

[0032] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A two-dimensional organic-inorganic heterostructure capable of generating interlayer excitons, characterized in that, The heterojunction exhibits two emission peaks in the 760-950 nm range in its photoluminescence spectrum measured at 83 K; the heterojunction is prepared by the following steps: S1. Preparation of bilayer pentacene crystals by physical vapor transport method; S2. Preparation of monolayer tungsten selenide crystals by mechanical exfoliation or chemical vapor deposition; S3. A monolayer tungsten selenide / bilayer pentacene heterojunction was prepared by transferring a monolayer tungsten selenide onto a bilayer pentacene using a dry transfer method.

2. A two-dimensional organic-inorganic heterostructure capable of generating interlayer excitons according to claim 1, characterized in that, The specific steps for preparing bilayer pentane crystals using the physical vapor transport method in step S1 are as follows: A 20 nm thick few-layer boron nitride is mechanically peeled off and placed onto the growth substrate; the pentane crystal powder is placed at the center of the tube furnace tube, and the growth substrate with boron nitride is placed 13-15 cm downstream of it; the furnace tube is then evacuated to 1 × 10⁻⁶. -4 After creating a vacuum environment, the furnace was heated to 130°C to grow pentaphenyl crystals for 30 minutes. The sample was then allowed to cool naturally to room temperature under the same vacuum. The number of layers was determined to find the desired bilayer pentaphenyl.

3. A two-dimensional organic-inorganic heterostructure capable of generating interlayer excitons according to claim 1, characterized in that, The growth substrate is selected as SiO2 / Si wafer.

4. A two-dimensional organic-inorganic heterostructure capable of generating interlayer excitons according to claim 1, characterized in that, The dry transfer described in step S3 is the PDMS-assisted transfer method.

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