阅读说明：本技术 一种二维原子晶体分子超晶格的制备方法 (Preparation method of two-dimensional atomic crystal molecular superlattice ) 是由 肖少庆 张露芳 南海燕 顾晓峰 于 2019-11-25 设计创作，主要内容包括：本发明公开了一种二维原子晶体分子超晶格的制备方法,属于二维半导体材料技术领域。所述制备方法包括以下步骤：将过渡金属硫族化合物薄层样品水平放置于由平面式螺旋电感天线产生的非平行板式电容耦合等离子体的等离子体腔室中,或垂直放置于由两平行板电极产生的电容耦合等离子体的等离子体腔室中,在低压环境下通入氧气,打开射频电源产生温和氧气等离子体,对过渡金属硫族化合物薄层样品进行等离子体插层处理,该方法在常温下调控过渡金属硫族化合物的插层程度来构造二维原子晶体分子超晶格,反应条件温和,操作简单,可控性强,环保无污染,成本低、插层均匀,可以实现大面积的插层,实用性较强。(The invention discloses a preparation method of a two-dimensional atomic crystal molecular superlattice, and belongs to the technical field of two-dimensional semiconductor materials. The preparation method comprises the following steps: the method comprises the steps of horizontally placing a transition metal chalcogenide thin-layer sample in a plasma chamber of non-parallel plate type capacitance coupling plasma generated by a planar spiral inductance antenna or vertically placing the transition metal chalcogenide thin-layer sample in a plasma chamber of capacitance coupling plasma generated by two parallel plate electrodes, introducing oxygen in a low-pressure environment, turning on a radio frequency power supply to generate mild oxygen plasma, and carrying out plasma intercalation treatment on the transition metal chalcogenide thin-layer sample.)

1. A method for preparing a two-dimensional atomic crystal molecular superlattice, the method comprising the steps of:

(1) horizontally placing the substrate carrying the transition metal chalcogenide thin layer sample in a plasma chamber of non-parallel plate type capacitance coupling plasma generated by a planar spiral inductance antenna or vertically placing the substrate in a plasma chamber of capacitance coupling plasma generated by two parallel plate electrodes, and pumping the chamber to the vacuum degree of 4.0 x 10^-3Pa below;

(2) introduction of O₂And opening a plasma radio frequency power supply to excite the temperature and oxygen plasma, and carrying out plasma intercalation treatment on the transition metal chalcogenide thin-layer sample to obtain the two-dimensional atomic crystal molecular superlattice of the transition metal chalcogenide.

2. The method of claim 1, wherein said transition metal chalcogenide of step (1) comprises MoS₂、WS₂、MoSe₂、ReS₂。

3. The method of claim 1, wherein the excitation temperature and the oxygen plasma in step (2) are selected from the group consisting of non-parallel plate-type capacitively coupled plasma generated by a planar spiral inductor antenna, and a plasma RF power frequency is 0.5-2MHz, and the substrate carrying the thin-layer sample of transition metal chalcogenide is horizontally placed in the plasma chamber in parallel with the planar spiral inductor antenna; the other is capacitance coupling plasma generated by two parallel plate electrodes, the frequency of a plasma radio frequency power supply is 0.5-13.56MHz, and a sample needs to be vertically placed in a plasma chamber and kept vertical to the two parallel plates.

4. A method for preparing a two-dimensional atomic crystal molecular superlattice as claimed in claim 1, wherein said plasma rf power source in step (2) has a power of 10-50W.

5. A method for preparing a two-dimensional atomic crystal molecular superlattice as claimed in claim 1, wherein O is introduced into said step (2)₂The flow rate of the gas is 5-50sccm, and the working air pressure is 1-50 Pa.

6. A method for preparing a two-dimensional atomic crystal molecular superlattice as claimed in claim 1, wherein said step (2) of subjecting the transition metal chalcogenide thin layer sample to plasma intercalation for 1-9 min.

7. A two-dimensional atomic crystal molecular superlattice produced by the production method according to any one of claims 1 to 6.

8. A photodetecting device comprising the two-dimensional atomic crystal molecular superlattice as claimed in claim 7.

9. An optoelectronic device comprising the two-dimensional atomic crystal molecular superlattice as claimed in claim 7.

10. Use of the method of any one of claims 1 to 6 or the two-dimensional atomic crystal molecular superlattice of claim 7 in the fields of micro-nano and semiconductors.

Technical Field

The invention relates to a preparation method of a two-dimensional atomic crystal molecular superlattice, belonging to the technical field of two-dimensional semiconductor materials.

Background

Since 2004, graphene invades the field of view of the public through a tape stripping method, and the heat tide of the two-dimensional layered semiconductor material is researched in each field. Monolayer two-dimensional layered materials are typically composed of a single atom or a lattice of covalent bonds that are multiple atoms thick. These nanoflakes exhibit extraordinary electronic and optoelectronic properties due to the absence of dangling bonds, in sharp contrast to conventional nanostructures that suffer from surface dangling bonds and trap states. Meanwhile, the adjacent layers of the two-dimensional layered materials are interacted by Van der Waals force, so that various nanoscale two-dimensional layered materials can be freely integrated to form various Van der Waals heterojunctions with atomic-level flat interfaces and non-diffusion of interlayer atoms, and even artificial two-dimensional atomic crystal superlattice structures. Conventional semiconductor superlattices can generally only be made of materials with highly similar lattice symmetry and therefore have very similar electronic structures. While the two-dimensional atomic crystal superlattice layers are distinct, it allows integration of two-dimensional layered materials of different heights without the constraints of lattice matching, and thus electronic properties and electronic energy bands that can be widely tuned, providing unique functional and technical applications far beyond existing materials, such as Field Effect Transistors (FETs) that are faster to fabricate and consume less energy, or more efficient Light Emitting Diodes (LEDs), etc. It is because two-dimensional atomic crystal superlattices have such a wide prospect in electronic and optoelectronic applications that they have recently received intense attention in the field of two-dimensional materials.

A typical method of making an artificial superlattice is by layer-by-layer lift-off and transfer stack formation by mechanical lift-off. "Cross-sectional imaging of induced layers and buried interfaces of graphene-based nanostructures and superstrates [ Nature Materials 2012,11,764 ]]This document describes the use of a method of transferring exfoliated graphene into hBN crystals to obtain a superlattice, which however does not allow production in a quantitative manner and lacks reproducibility. Meanwhile, a high-quality heterojunction structure, namely 'Vertical and in-plane heterojunction structures' from WS can be prepared by using a chemical vapor deposition mode₂/MoS₂monolayers[Nature Materials 2014,13,1135-1142]This document describes the preparation of vertically stacked WS using a one-step chemical vapor deposition process₂/MoS₂Heterojunction and lateral WS₂/MoS₂Chemical vapor synthesis of heterojunctions, but vertical superlattices (periodic stacks of different two-dimensional materials) remains a great challenge because different conditions (such as heat, pressure and chemical environment) are required to superimpose each layer during the vertical stacking process, which is likely to cause the underlying two-dimensional material to be altered or destroyed. Furthermore, the insertion of alkali metal ions into two-dimensional atomic crystals by electrochemical reaction is a new method for preparing superlattice structures, "applying the limits of transparency and conductivity in the gradient materials through superlattice structures [ Nature communication 2014,5,4224]"this document forms LiC by inserting lithium ions into ultra-thin graphite nanoplatelets (multi-layer graphene) through an electrochemical reaction₆However, the superlattice structure of (2) has a problem of low stability. "Monomerayerate crystalline molecular superstrates [ Nature 2018,555(7695) ]231-]"this document develops methods of such electrochemical intercalation by injecting negatively charged electrons into a two-dimensional material and then attracting positively charged ammonium molecules into the interstices between the atomic layers of the two-dimensional material, which self-assemble into new layers in an ordered crystal structure, thereby forming a superlattice of two-dimensional atomic crystal molecules. The superlattice prepared by the method has various ideal electrical and optical properties, but the method needs bulk crystals as raw materials, and has large consumption of raw materials and high cost.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method of a two-dimensional atomic crystal molecular superlattice based on mild oxygen plasma, the method constructs the two-dimensional atomic crystal molecular superlattice through plasma intercalation at normal temperature, the reaction condition is mild, the operation is simple, the controllability is strong, the environment is protected, no pollution is caused, the preparation in a large area can be realized, and the practicability is strong.

A first object of the present invention is to provide a method for preparing a two-dimensional atomic crystal molecular superlattice, the method comprising the steps of:

(1) horizontally placing the substrate carrying the transition metal chalcogenide thin layer sample in a plasma chamber of non-parallel plate type capacitance coupling plasma generated by a planar spiral inductance antenna or vertically placing the substrate in a plasma chamber of capacitance coupling plasma generated by two parallel plate electrodes, and pumping the chamber to the vacuum degree of 4.0 x 10^-3Pa below;

(2) introduction of O₂And opening a plasma radio frequency power supply to excite the temperature and oxygen plasma, and carrying out plasma intercalation treatment on the transition metal chalcogenide thin-layer sample to obtain the two-dimensional atomic crystal molecular superlattice of the transition metal chalcogenide.

In one embodiment, the transition metal chalcogenide comprises MoS₂、WS₂、MoSe₂、ReS₂。

In one embodiment, the thin layer sample of transition metal chalcogenide has a thickness of 1.3 to 6.5nm (2 to 10 layers).

In one embodiment, the method for preparing the transition metal chalcogenide thin layer sample includes any one or more of a mechanical lift-off method, a sputtering method, a chemical vapor deposition method, a plasma enhanced vapor deposition method, a low pressure chemical vapor deposition method, a molecular beam epitaxy method, and an atomic layer deposition method.

In one embodiment, the substrate of the thin transition metal chalcogenide layer includes any one of a silicon substrate, a silicon substrate with a silicon dioxide layer attached to a surface thereof, sapphire, copper, PDMS, and glass.

In one embodiment, the substrate is cleaned by: sequentially putting the mixture into acetone, ethanol and deionized water, ultrasonically cleaning the mixture for 5 minutes respectively to remove organic matters on the surface, baking the mixture on a heating platform at the ultrasonic frequency of 25KHz for 30 minutes at the temperature of 350 ℃ to remove residues such as acetone, ethanol and the like.

In one embodiment, the excitation temperature and the oxygen plasma have two modes, one mode is a non-parallel plate type capacitance coupling plasma generated by a planar spiral inductance antenna, the frequency of a plasma radio frequency power supply is 0.5-2MHz, and a substrate carrying a transition metal chalcogenide thin-layer sample needs to be horizontally placed in a plasma chamber and is parallel to the planar spiral inductance antenna; the other is capacitance coupling plasma generated by two parallel plate electrodes, the frequency of a plasma radio frequency power supply is 0.5-13.56MHz, and a sample needs to be vertically placed in a plasma chamber and kept vertical to the two parallel plates.

In one embodiment, the plasma RF power source has a power in the range of 10-50W.

In one embodiment, the O is₂The flow rate is 5-50sccm (standard milliliters per minute) and the working gas pressure is 1-50 Pa.

In one embodiment, the oxygen plasma treatment time is 1-9 min.

The second purpose of the invention is to provide the two-dimensional atomic crystal molecular superlattice prepared by the method.

The third purpose of the invention is to provide a light detection device, wherein the light detection device comprises the two-dimensional atomic crystal molecular superlattice prepared by the method.

A fourth object of the present invention is to provide an optoelectronic device comprising the two-dimensional atomic crystal molecular superlattice prepared by the above method.

In one embodiment, the method for manufacturing the optoelectronic device comprises: preparing molybdenum disulfide and tungsten diselenide heterojunction, depositing Ni/Au (5nm/50nm) source/drain electrodes by adopting electron beam lithography and electron beam evaporation to form a device, horizontally placing a heterojunction sample in a non-parallel plate type capacitive coupling plasma chamber generated by a planar spiral inductance antenna, and then introducing O in a low-pressure environment₂And opening a plasma radio frequency power supply to excite the temperature and oxygen plasma, and carrying out plasma intercalation treatment on the heterojunction sample.

The fifth purpose of the invention is to provide the application of the two-dimensional atomic crystal molecular superlattice prepared by the preparation method or the method in the fields of micro-nano and semiconductor.

The invention has the beneficial effects that:

1. the plasma is mild and the whole process is not applied to the thin transition metal chalcogenide (such as MoS)₂) The sample produced significant bombardment and thinning.

2. The intercalation degree can be regulated and controlled by controlling the processing parameters of the plasma.

3. The intercalation of the processed area is uniform, and large-scale uniform two-dimensional atomic crystal molecular superlattice can be obtained.

4. Compared with the intercalation of chemical solution, the method has the advantages of low cost of raw materials, environmental protection and no pollution.

5. The method has good repeatability and strong controllability, can realize the preparation of the two-dimensional atomic crystal molecular superlattice, and is beneficial to promoting the development of two-dimensional materials in the micro-nano industry and the semiconductor industry.

Drawings

FIG. 1 is a flow chart of a process for preparing a two-dimensional atomic crystal molecular superlattice from a non-parallel plate type capacitively coupled plasma generated by a planar spiral inductive antenna.

FIG. 2 is a flow chart of a process for preparing a two-dimensional atomic crystal molecular superlattice from capacitively coupled plasma generated by two parallel plate electrodes.

FIG. 3 multilayer molybdenum disulfide (MoS)₂) To two-dimensional atomic crystal molecular superlattices (MoS)₂/O₂Superlattice).

FIG. 4 is a fluorescent characterization of 4 layers of molybdenum disulfide as a function of treatment time.

Figure 5 is a raman characterization of 4 layers of molybdenum disulfide as a function of treatment time.

FIG. 6 shows molybdenum disulfide and MoS₂/O₂Transmission electron microscopy of the superlattice.

Figure 7 is a fluorescent characterization of 3 layers of molybdenum disulfide as a function of treatment time.

Figure 8 is a fluorescent characterization of 2 layers of molybdenum disulfide as a function of treatment time.

Figure 9 is a fluorescence characterization of 6 layers of molybdenum disulfide as a function of treatment time.

Fig. 10 is a graph of the photoresponse of tungsten diselenide and molybdenum disulfide heterojunction transistors as a function of mild oxygen plasma treatment time.

Figure 11 is a fluorescent characterization of 4 layers of molybdenum disulfide as a function of treatment time (placed vertically in a non-parallel plate capacitively coupled plasma).

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The intercalation principle of the invention is shown in fig. 3, as can be seen from fig. 3: original molybdenum disulfide layer spacing of

After oxygen plasma treatment, oxygen ions are inserted into van der Waals gaps between the transition metal chalcogenide layers to widen the spacing thereof and form a two-dimensional atomic crystal molecular superlattice

The calculation method of the distance between the molybdenum disulfide layers comprises the following steps: performing first principle calculation by adopting VASP software and a PAW method, and applying exchange correlation functions introduced by Perew, Burke and Ernzerhproof (PBE) in the calculation. Use of VASP software and related methods is described in "First-principles study of O-BN: A sp³-bonding boron nitrideallotrope[Journal of Applied Physics 2012 112(5)053518]”，“First-principlescalculation of mechanical properties of Si<001>nanowires and comparison tonanomechanical theory[Physical Review B Condensed Matter 2007 75(19)195328]”，“From ultrasoft pseudopotentials to the projector augmented-wave method[Physical review B 1999 59(3)1758-1775]”，“Generalized gradient approximationmade simple[Physical review letters 1996 77(18)3865]"in (1).