CN112397154A - Construction method of two-dimensional Schottky heterojunction model based on germanium alkene - Google Patents

Abstract

The invention discloses a method for constructing a two-dimensional Schottky heterojunction model based on germanium alkene, which comprises the following steps: establishing WSe₂A bulk material model; establishing a Germanene model; WSe₂Uniformly cutting crystal faces of a bulk material model to obtain single-layer WSe₂Uniformly cutting a crystal face of the Germanene model to obtain a Germanene thin layer; germanene supercells were created according to the Germanene thin layer, WSe according to monolayer₂Establishing WSe₂The supercell of Germanene is vertically superposed on WSe₂On the supercell to obtain Germanene/WSe₂A heterojunction model. According to the invention, germanium alkene is vertically stacked on a single layer of tungsten diselenide for the first time, and lattice parameters, energy band structures, thermodynamic stability, electron effective quality and the like of the supercell are calculated.

Description

Construction method of two-dimensional Schottky heterojunction model based on germanium alkene

Technical Field

The invention belongs to the technical field of two-dimensional heterojunction theoretical modeling, and particularly relates to a construction method of a two-dimensional Schottky heterojunction model based on germanium alkene.

Background

Two-dimensional transition metal chalcogenide (2D-TMDs), phosphenes, silylene, germanium alkene and the like are novel graphene-like materials appearing in recent years, and the unique two-dimensional structure can combine the excellent electrical, magnetic and optical properties under the microscopic level with the ultrathin property, the transparency and the flexibility under the macroscopic level to realize miniaturized devices. However, the application of a single two-dimensional material has a certain limitation, for example, the photoelectric conversion efficiency of a single-layer tungsten diselenide solar cell is only 0.5%, and the single-layer tungsten diselenide solar cell is difficult to be applied to a solar device alone. Germanium alkene is zero band gap, can change the nature along with temperature increase, leads to that germanium alkene is main to be destroyed up to several hundred degrees centigrade transistor, has restricted its application in the optoelectronic field.

In recent years, researchers have found that two-dimensional materials are stacked together to form a heterojunction, weak van der waals acting force exists between layers, inherent electronic properties of the materials are well protected, and the materials have many novel photoelectronic characteristics, so that the device performance is further improved.

Disclosure of Invention

The invention aims to provide a method for constructing a two-dimensional Schottky heterojunction model based on germanium alkene.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the invention provides a method for constructing a two-dimensional Schottky heterojunction model based on germanium alkene, which comprises the following steps:

the model establishment is completed on Materials Studio 8.0 software, which is simulation software developed by Accelrys corporation specially for the field of material science and capable of running on a PC, and integrates various advanced methods and excellent modeling and visualization in the current molecular simulation field.

The first step is as follows: setting space group P6/mmm, and lattice constant as follows:

gamma 120 deg., establish WSe₂Bulk Material model, WSe₂The crystal has a layered structure;

the second step is that: the space group is set to P6/mmm,the lattice constant is:

b is a, height of corrugation

Gamma is 120 degrees, a Germanene model is established, and the Germanene crystal has a hexagonal honeycomb structure;

the third step: the WSe prepared in the first step₂Uniformly cutting (001) crystal face on the bulk material model to obtain single-layer WSe₂Uniformly cutting a (001) crystal face of the Germanene model prepared in the second step to obtain a Germanene thin layer;

the fourth step: establishing a 4X 4 or 3X 3Germanene supercell according to the Germanene thin layer prepared in the third step, and preparing a single layer WSe according to the third step₂Establishing a 5 × 5 or 4 × 4WSe₂The supercell of (4X 4) Germanene is vertically superposed on 5X 5WSe₂Or 3X 3Germanene supercells are vertically superposed on 4X 4WSe₂On the supercell to obtain Germanene/WSe₂A heterojunction model.

The Germanene/WSe₂The heterojunction model is in a single layer WSe₂Germanene is in a single-layer fluctuant germanium honeycomb structure, Ge atoms are combined by covalent bonds, and a single layer WSe is formed₂Is a sandwich structure consisting of Se-W-Se, and a covalent bond is formed between a W atom and a Se atom.

The Germanene/WSe₂The lattice mismatch ratio of the heterojunction model is defined as (a)₁-a₂)/a₁Wherein a is₁And a₂Are respectively WSe₂And the lattice constant of the Germanene optimized supercell. The optimization method comprises the following steps: the structure is optimized by adopting a Broyden-Fletcher-Goldfarb-Shanno (BFGS) scheme, the plane wave function cutoff energy is set to be 400eV, and the energy convergence standard is 5.0 x 10 in the process of structure relaxation^-7eV/atom, force per atom less than

The component of atomic displacement being less than

The stress is less than 0.02 GPa. Wherein the superlattice constant a (a ═ b) of 4X 4 or 3X 3Germane is

And

5X 5 or 4X 4WSe₂Has a superlattice constant a (a ═ b) of

And

because the thickness of the vacuum layer of the slice model is selected as the thickness in the calculation

The heterojunction superlattice lattice constant c is not explained.

The Germanene/WSe₂The formation energy, the binding energy and the mismatch energy of the heterojunction model are respectively defined as:

wherein E is_formTo form energy, E_cohAs binding energy, Δ E_mismatchIn order to be able to mismatch the energy,

is Germanene/WSe₂Lattice of heterojunction modelNumber is

The total energy of (2) was-64842.67 eV. E_(Germanene)Is the Germanene lattice constant

The energy at time was-3419.12 eV.

Is WSe₂Lattice constant

The energy at time was-61417.82 eV. E_(Germanene)aIs the Germanene lattice constant

The energy at time was-3419.00 eV.

Is WSe₂Lattice constant

The energy at time was-61417.80 eV. A is Germanene/WSe₂Area of the heterojunction model of

Germanene/WSe from formula (1), formula (2) and formula (3)₂Formation energy of heterojunction model E_formIs composed of

Binding energy E_cohIs composed of

Mismatch energy Δ E_mismatchIs composed of

The Germanene/WSe₂The magnitude of the interlayer force of the heterojunction model is determined by lattice mismatch energy and binding energy, and is defined as:

ΔE_vdW＝|ΔE_mismach|+|E_coh| (4)

ΔE_vdwthe energy caused by the interlayer acting force is calculated to obtain Delta E_vdwIs composed of

Due to the interlayer forces of most van der Waals force heterojunctions

Within the interval, it can therefore be concluded that Germanene/WSe₂The heterojunction model belongs to van der waals heterojunction, and the type of bonding between two layers is physical adsorption.

The Germanene/WSe₂The calculation of the electronic performance of the heterojunction model is completed by CAStep code based on the first principle of density functional DFT, the calculation is realized in Materials Studio software, the electronic exchange related interaction is processed by adopting generalized gradient approximation GGA and functional PBE, DFT-D approximation is realized by adopting a Tkatchenko and Scheffler (TS) scheme, the interaction of ions and electrons can be described by ultra-soft pseudopotentials, the structure is optimized by adopting a Broyden-Fletcher-Goldfarb-Shanno (BFBFGS) scheme, the plane wave function truncation energy is set to be 400eV, and the energy convergence standard is 5.0 multiplied by 10 eV in the process of structure relaxation^-7eV/atom, force per atom less than

The component of atomic displacement being less than

The stress is less than 0.02 GPa. The thickness of the vacuum layer of the lamella model is selected as

The Germanene/WSe₂Two-dimensional way of using GGA-PBE form for energy band of heterojunction modelDiameter G (000) -M (00.50) -K (-0.333-0.6670) -G (000), single layer WSe₂Is a direct band gap with a forbidden band width of 1.532eV, see fig. 2 a; the VBM of the top of the valence band and the CBM of the bottom of the conduction band are positioned at a point K; Germanene/WSe₂The heterojunction model is a typical schottky heterojunction, forming a p-type schottky contact, where germane has a band gap at point K that is nearly zero small, see fig. 2 d. This is mainly due to Germanene and WSe₂The interaction forces break the band gap that occurs with the sublattice symmetry of germane. Germanene/WSe₂The band structures of the heterojunctions appear to be Germanene and single layer WSe₂Is an important feature of two-dimensional vdW heterostructures, so that the electronic structure of the heterojunction largely retains germane and WSe₂The layers are each independent of the electronic structure.

Germanene/WSe₂Germanene and WSe in heterojunctions₂The band dispersion relationship of (a) is essentially unchanged and reference is made to fig. 2a, b and c, which illustrate that the heterojunction maintains its respective independent electronic structure while generating new electronic properties.

The Germanene/WSe₂The interface spacing of the heterojunction model is

The band gap opening value is 10-45 meV; germanene and WSe₂The heterojunction is formed with high carrier mobility.

The Germanene/WSe₂Metallic Germanene and semiconductor monolayer WSe in heterojunction model₂Germanene/WSe at equilibrium interlayer spacing₂Electrostatic potential of heterojunction in Z-direction, single-layer WSe₂Have deeper potentials than Germanene, Germanene and WSe₂A potential difference of electrostatic (potential drop) between up to 12.3 eV; Germanene/WSe₂The heterojunction model preserves germanne's high carrier mobility.

The Germanene/WSe₂In the heterojunction model, the effective mass is defined as:

where k is the wave vector,

is a simplified planck constant, m is the effective mass, and E is the energy. Under the action of different interface distances, the effective masses of electrons and holes of the heterojunction are shown in figure 3b, the visible interface distance and the electric field have certain regulation effect on the carrier mobility, and in an equilibrium state, the effective mass of the electrons is 0.57m₀Effective mass of holes is-0.56 m₀When the interface spacing is

The effective mass of the electron and hole is 0.70m, respectively₀And-0.73 m₀And thus has a higher carrier mobility.

Due to the adoption of the technical scheme, the invention has the following advantages and beneficial effects:

according to the method for constructing the two-dimensional Schottky heterojunction model based on the germanium alkene, the two-dimensional Schottky heterojunction model based on the germanium alkene is suitable for a Schottky heterojunction system, especially a two-dimensional Schottky heterojunction system; the theoretical model is composed of two-dimensional materials, and is formed by combining WSe₂Cutting (001) crystal face of the Germanene material to obtain Germanene/WSe₂A heterojunction model; the theoretical model considers lattice mismatch of a heterojunction model, establishes a supercell and analyzes the formation stability of a heterojunction; the theoretical model adopts a first principle based on a Density Functional (DFT) to disclose the influence mechanism of an energy band structure and a layer spacing on the effective quality of a heterojunction.

The invention vertically stacks germanium alkene (Germanene) on a single layer of tungsten diselenide (WSe) for the first time₂) And a density functional theory based on a first sexual principle is adopted for Germanene/WSe₂The heterojunction is researched, lattice parameters, energy band structures, thermodynamic stability and the like of the supercell are calculated, and meanwhile, the influence mechanism of the interface spacing on the effective quality of the heterojunction is provided.

Drawings

FIG. 1 shows Germanene/WSe prepared according to an embodiment of the present invention₂Structural schematic diagram of heterojunction model, in the figure, a is a supercell of 3X 3Germanene vertically superposed on 4X 4WSe₂Germanene/WSe obtained from Supercell of (1)₂A heterojunction model schematic diagram; supercells with b 4X 4Germanene vertically superimposed on 5X 5WSe₂Germanene/WSe obtained from Supercell of (1)₂A schematic top view of a heterojunction model; supercell with c being Germanene vertically superposed on 5X 5WSe₂Germanene/WSe obtained from Supercell of (1)₂The heterojunction model is schematically shown from the side.

FIG. 2 shows Germanene/WSe prepared according to an embodiment of the present invention₂Energy band diagrams of the heterojunction model, a, b and c are single-layer WSe₂Germanene and Germanene/WSe₂Band diagram of heterojunction model, d is Germane/WSe₂The heterojunction model band is magnified at the dirac point.

FIG. 3 shows Germanene/WSe prepared according to an embodiment of the present invention₂The band gap and electron hole effective mass curve chart of the heterojunction model, a is Germanene/WSe under different interface pitches₂Band gap of heterojunction, b is Germanene/WSe under different interface pitches₂Electron hole effective mass of the heterojunction.

FIG. 4 shows Germanene/WSe₂Schematic of electrostatic potential of the heterojunction in the Z-direction at different interface pitches.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

Example 1

A construction method of a two-dimensional Schottky heterojunction model based on germanium alkene comprises the following steps:

the model establishment is completed on Materials Studio 8.0 software, which is simulation software developed by Accelrys corporation specially for the field of material science and capable of running on a PC, and integrates various advanced methods and excellent modeling and visualization in the current molecular simulation field.

The first step is as follows: setting space group P6/mmm, and lattice constant as follows:

b＝a，

gamma 120 deg., establish WSe₂Bulk Material model, WSe₂The crystal has a layered structure;

the second step is that: setting space group as P6/mmm, lattice constant as:

b is a, height of corrugation

Gamma is 120 degrees, a Germanene model is established, and the Germanene crystal has a hexagonal honeycomb structure;

the third step: the WSe prepared in the first step₂Uniformly cutting (001) crystal face on the bulk material model to obtain single-layer WSe₂Uniformly cutting a (001) crystal face of the Germanene model prepared in the second step to obtain a Germanene thin layer;

the fourth step: establishing a 4X 4 or 3X 3Germanene supercell according to the Germanene thin layer prepared in the third step, and preparing a single layer WSe according to the third step₂Establishing a 5 × 5 or 4 × 4WSe₂The supercell of (4X 4) Germanene is vertically superposed on 5X 5WSe₂Or 3X 3Germanene supercells are vertically superposed on 4X 4WSe₂On the supercell to obtain Germanene/WSe₂A heterojunction model.

The Germanene/WSe₂The heterojunction model is in a single layer WSe₂Germanene is in a single-layer fluctuant germanium honeycomb structure, Ge atoms are combined by covalent bonds, and a single layer WSe is formed₂Is a sandwich structure consisting of Se-W-Se, and a covalent bond is formed between a W atom and a Se atom. As shown in FIG. 1, FIG. 1 shows Germanene/WSe prepared according to an embodiment of the present invention₂Structural schematic diagram of heterojunction modelIn the figure, a is a supercell of 3X 3Germane vertically superposed on 4X 4WSe₂Germanene/WSe obtained from Supercell of (1)₂A heterojunction model schematic diagram; supercells with b 4X 4Germanene vertically superimposed on 5X 5WSe₂Germanene/WSe obtained from Supercell of (1)₂A schematic top view of a heterojunction model; supercell with c being Germanene vertically superposed on 5X 5WSe₂Germanene/WSe obtained from Supercell of (1)₂The heterojunction model is schematically shown from the side.

The lattice constants a (a ═ b) of the heterojunction supercells in a and b in FIG. 1 are respectively

And

the combination of heterojunctions with a lattice mismatch of less than 5%, the Germanene/WSe, is commonly referred to as lattice matching₂The lattice mismatch ratio of the heterojunction model is defined as (a)₁-a₂)/a₁Wherein a is₁And a₂Are respectively WSe₂And the lattice constant of the Germanene optimized supercell. The optimization method comprises the following steps: the structure is optimized by adopting a Broyden-Fletcher-Goldfarb-Shanno (BFGS) scheme, the plane wave function cutoff energy is set to be 400eV, and the energy convergence standard is 5.0 x 10 in the process of structure relaxation^-7eV/atom, force per atom less than

The component of atomic displacement being less than

The stress is less than 0.02 GPa. Wherein the superlattice constant a (a ═ b) of 4X 4 or 3X 3Germane is

And

5X 5 or 4X 4WSe₂Has a superlattice constant a (a ═ b) of

And

because the thickness of the vacuum layer of the slice model is selected as the thickness in the calculation

The heterojunction superlattice lattice constant c is not explained. The lattice mismatch ratios were calculated to be 7.2% and 1.1%, respectively. Thus, the supercells of 4X 4Germanene are vertically stacked at 5X 5WSe₂Germanene/WSe obtained from Supercell of (1)₂The heterojunction model can form a better match and the following analysis is based on the model of fig. 1 b.

In order to examine the difficulty and stability of heterojunction formation in the experiment, Germanene/WSe was calculated₂The formation energy, the binding energy and the mismatch energy of the heterojunction model are respectively defined as:

wherein E is_formTo form energy, E_cohAs binding energy, Δ E_mismatchIn order to be able to mismatch the energy,

is Germanene/WSe₂The lattice constant of the heterojunction model is

The total energy of (2) was-64842.67 eV. E_(Germanene)Is a Germanene latticeConstant number

The energy at time was-3419.12 eV.

Is WSe₂Lattice constant

The energy at time was-61417.82 eV. E_(Germanene)aIs the Germanene lattice constant

The energy at time was-3419.00 eV.

Is WSe₂Lattice constant

The energy at time was-61417.80 eV. A is Germanene/WSe₂Area of the heterojunction model of

Germanene/WSe from formula (1), formula (2) and formula (3)₂Formation energy of heterojunction model E_formIs composed of

Binding energy E_cohIs composed of

Mismatch energy Δ E_mismatchIs composed of

Negative formation and binding energies indicate Germanene/WSe₂The heterojunction model is an easily formed and stable heterojunction. This result is similar in magnitude to that of two-dimensional heterostructures, such as graphene/MoS₂Graphene/phosphene and graphene/g-GaN.

The Germanene/WSe₂The magnitude of the interlayer force of the heterojunction model is determined by lattice mismatch energy and binding energy, and is defined as:

ΔE_vdW＝|ΔE_mismach|+|E_coh| (4)

ΔE_vdwthe energy caused by the interlayer acting force is calculated to obtain Delta E_vdwIs composed of

Due to the interlayer forces of most van der Waals force heterojunctions

Within the interval, it can therefore be concluded that Germanene/WSe₂The heterojunction model belongs to van der waals heterojunction, and the type of bonding between two layers is physical adsorption.

The Germanene/WSe₂The calculation of the electronic performance of the heterojunction model is completed by CAStep code based on the first principle of density functional DFT, is realized in Materials Studio software, adopts generalized gradient approximation GGA and functional PBE to process the electronic exchange related interaction, and because Germanene and WSe₂The strong bonding interaction is lacked, and the weak vdW interaction is expected to play an important role. In order to obtain the accurate structure of the heterostructure in calculation, DFT-D approximation is realized by adopting a Tkatchenko and Scheffler (TS) scheme, the interaction of ions and electrons can be described by ultra-soft pseudopotential, the structure is optimized by adopting a Broyden-Fletcher-Goldfarb-Shanno (BFGS) scheme, the plane wave function truncation energy is set to be 400eV, and the energy convergence standard is 5.0 x 10 in the process of structure relaxation^-7eV/atom, force per atom less than

The component of atomic displacement being less than

The stress is less than 0.02 GPa. The thickness of the vacuum layer of the lamella model is selected as

As shown in FIG. 2, FIG. 2 shows Germanene/WSe prepared according to an embodiment of the present invention₂Energy band diagrams of the heterojunction model, a, b and c are single-layer WSe₂Germanene and Germanene/WSe₂Band diagram of heterojunction model, d is Germane/WSe₂The heterojunction model band is magnified at the dirac point. The Germanene/WSe₂The energy band of the heterojunction model uses the two-dimensional pathway of GGA-PBE form G (000) -M (00.50) -K (-0.333-0.6670) -G (000), and it can be seen that the WSe of a single layer is₂Is a direct band gap with a forbidden band width of 1.532eV, see fig. 2 a; the VBM of the top of the valence band and the CBM of the bottom of the conduction band are positioned at a point K; the pi and pi-bands of germanne cross at dirac points and cross the fermi level with a linear dirac cone, thus having semi-metallic properties, similar to graphene. As compared to Germanene alone, it can be seen that Germanene/WSe₂The heterojunction model is a typical schottky heterojunction, forming a p-type schottky contact, where the dirac cone of germane is well preserved. At the same time, germane was found to have a band gap at the K point which is small, almost zero, as shown in the graph d. This is mainly due to Germanene and WSe₂The interaction forces break the band gap that occurs with the sublattice symmetry of germane. Germanene/WSe₂The band structures of the heterojunctions appear to be Germanene and single layer WSe₂Is an important feature of two-dimensional vdW heterostructures, so that the electronic structure of the heterojunction largely retains germane and WSe₂The layers are each independent of the electronic structure. Germanene/WSe₂Germanene and WSe in heterojunctions₂The band dispersion relationship of (a) is essentially unchanged and reference is made to fig. 2a, b and c, which illustrate that the heterojunction maintains its respective independent electronic structure while generating new electronic properties.

The Germanene/WSe₂The interface spacing of the heterojunction model is

The band gap opening value is 10-45 meV; germanene and WSe₂The heterojunction is formed with high carrier mobility. As shown in FIG. 3, FIG. 3 shows Germanene/WSe prepared according to an embodiment of the present invention₂The band gap and electron hole effective mass curve chart of the heterojunction model, a is Germanene/WSe under different interface pitches₂Band gap of heterojunction, b is Germanene/WSe under different interface pitches₂Electron hole effective mass of the heterojunction. From a, the energy dispersion relation of the conduction band bottom and valence band top near the Fermi level Dirac point can be seen at different interface pitches. The position of the pi band of Germanene is unchanged, and the Dirac cone angle formed by the pi band and the pi band is gradually reduced. Variation in the position of the pi bands of Germanene, spacing at the interface

When the band gap of Germanene is the farthest from the Fermi level, the band gap opening value is 45meV, and when the interface distance is

At this time, the band gap opening value decreases to a minimum value of 10meV, and increases from 10meV to 27meV (interface spacing: 10 meV) with an increase in interface spacing

) Then reduced to 17meV (interfacial spacing of

). Accordingly, Germanene/WSe₂The band gap opening value of the heterojunction at the dirac point is very sensitive to the lattice symmetry of the heterojunction and is influenced by the interface spacing. From b, it can be seen that when the interface spacing is

The effective mass of electrons and holes is at their maximum, 0.70m each₀And-0.73 m₀Is increased to

The effective mass of electrons and holes decreases and remains substantially unchanged. When in flatAt the equilibrium layer spacing, the effective masses of electrons and holes at the K Dirac point were calculated to be 0.53 and 0.51m₀Specification of Germanene and WSe₂The heterojunction has high carrier mobility when formed, so that the heterojunction becomes a material suitable for high-speed nano electronic and optoelectronic devices.

The Germanene/WSe₂In the heterojunction model, the effective mass is defined as:

where k is the wave vector,

is a simplified planck constant. Under the action of different interface distances, the effective masses of electrons and holes of the heterojunction are shown in figure 3b, the visible interface distance and the electric field have certain regulation effect on the carrier mobility, and in an equilibrium state, the effective mass of the electrons is 0.57m₀Effective mass of holes is-0.56 m₀When the interface spacing is

The effective mass of the electron and hole is 0.70m, respectively₀And-0.73 m₀And thus has a higher carrier mobility.

FIG. 4 shows Germanene/WSe₂Electrostatic potential of the heterojunction in the Z-direction is schematically shown. The Germanene/WSe₂Metallic Germanene and semiconductor monolayer WSe in heterojunction model₂Germanene/WSe at equilibrium interlayer spacing₂Electrostatic potential of heterojunction in Z-direction, single-layer WSe₂Has a deeper potential than Germanene, and in addition, due to Germanene and WSe₂The electrostatic potential difference (potential drop) between them is as high as 12.3eV, so that a strong electrostatic field exists across the van der waals heterojunction, which has a large influence on the injection of charges when the germane layer is used as an electrode. Germanene/WSe₂The heterojunction maintains the high carrier mobility of Germanene.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

Translated fromChinese

1.一种基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，包括以下步骤：1. a construction method based on the two-dimensional Schottky heterojunction model of germanene, is characterized in that, comprises the following steps:第一步：设定空间群P6/mmm，晶格常数为：

b＝a，

γ＝120°，建立WSe₂体材料模型，WSe₂晶体具有层状结构；Step 1: Set the space group P6/mmm, and the lattice constant is:

b=a,

γ=120°, the WSe₂ bulk material model is established, and the WSe₂ crystal has a layered structure;第二步：设定空间群为P6/mmm，晶格常数为：

b＝a，起皱高度

γ＝120°，建立Germanene模型，Germanene晶体具有六角形蜂巢结构；Step 2: Set the space group to P6/mmm and the lattice constant to:

b=a, wrinkle height

γ=120°, establish Germanene model, Germanene crystal has hexagonal honeycomb structure;第三步：将第一步制备的WSe₂体材料模型均切001晶面得到单层WSe₂，将第二步制备的Germanene模型均切001晶面得到Germanene薄层；The third step: cut the WSe₂ bulk material model prepared in the first step into the 001 crystal plane to obtain a single-layer WSe₂ , and cut the Germanene model prepared in the second step into the 001 crystal plane to obtain a Germanene thin layer;第四步：根据第三步制备的Germanene薄层建立4×4或3×3Germanene的超胞，根据第三步制备的单层WSe₂建立5×5或4×4WSe₂的超胞，将4×4Germanene的超胞垂直叠加在5×5WSe₂的超胞上或将3×3Germanene的超胞垂直叠加在4×4WSe₂的超胞上，得到Germanene/WSe₂异质结模型；Step 4: Create a 4×4 or 3×3 Germanene supercell based on the Germanene thin layer prepared in the third step, and create a 5×5 or 4×4WSe₂ supercell based on the single-layer WSe₂ prepared in the third step. The supercell of ×4Germanene is vertically superimposed on the supercell of 5×5WSe₂ or the supercell of 3×3Germanene is vertically superimposed on the supercell of 4×4WSe₂ to obtain the Germanene/WSe₂ heterojunction model;所述模型建立是在Materials Studio 8.0软件上完成。The model building was done on Materials Studio 8.0 software.2.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型是在单层WSe₂衬底上垂直堆叠锗烯而成，有两种堆叠方式，Germanene呈现单层起伏的锗蜂窝状结构，Ge原子以共价键结合而成，单层WSe₂是由Se-W-Se组成的三明治结构，W原子和Se原子之间为共价键。2. The method for constructing a germanene-based two-dimensional Schottky heterojunction model according to claim 1, wherein the Germanene/WSe₂ heterojunction model is vertical on a single-layer WSe₂ substrate It is made of stacked germanene. There are two stacking methods. Germanene presents a single-layer undulating germanium honeycomb structure, and Ge atoms are formed by covalent bonding. The single-layer WSe₂ is a sandwich structure composed of Se-W-Se. There is a covalent bond between the atom and the Se atom.3.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型的晶格失配率定义为(a₁-a₂)/a₁，其中a₁和a₂分别为WSe₂和Germanene优化后超胞的晶格常数。3. the construction method of the two-dimensional Schottky heterojunction model based on germanene according to claim 1, is characterized in that, the lattice mismatch rate of described Germanene/WSe₂ heterojunction model is defined as (a₁ -a₂ )/a₁ , where a₁ and a₂ are the lattice constants of the WSe₂ and Germanene optimized supercells, respectively.4.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型的形成能、结合能和失配能，分别定义为：4. The method for constructing a germanene-based two-dimensional Schottky heterojunction model according to claim 1, wherein the formation energy, binding energy and mismatch energy of the Germanene/WSe₂ heterojunction model , which are respectively defined as:

其中，E_form为形成能，E_coh为结合能，ΔE_mismatch为失配能，

为Germanene/WSe₂异质结模型的晶格常数为

的总能量；E_(Germanene)为Germanene晶格常数

时的能量；

为WSe₂晶格常数

时的能量；E_(Germanene)a为Germanene晶格常数

时的能量；

为WSe₂晶格常数

时的能量；A为Germanene/WSe₂异质结模型的面积。where E_form is the formation energy, E_coh is the binding energy, ΔE_mismatch is the mismatch energy,

The lattice constant for the Germanene/WSe₂ heterojunction model is

The total energy of ; E_(Germanene) is the Germanene lattice constant

time energy;

is the lattice constant of WSe₂

energy at ; E_{(Germanene) a} is the Germanene lattice constant

time energy;

is the lattice constant of WSe₂

energy; A is the area of the Germanene/WSe₂ heterojunction model.5.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型的层间作用力的大小由晶格失配能和结合能决定，定义为：5. The method for constructing a germanene-based two-dimensional Schottky heterojunction model according to claim 1, wherein the magnitude of the interlayer force of the Germanene/WSe₂ heterojunction model is determined by the lattice The mismatch and binding energies determine, defined as:ΔE_vdW＝|ΔE_mismach|+|E_coh| (4)ΔE_vdW = |ΔE_mismach |+|E_coh | (4)ΔE_vdw为层间作用力引起的能量。ΔE_vdw is the energy caused by the interlayer force.6.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型的电子性能的计算是基于密度泛函DFT的第一性原理的CASTEP代码完成，在Materials Studio软件中实现，采用广义梯度近似GGA和泛函PBE处理电子交换相关相互作用，采用Tkatchenko and Scheffler方案实现了DFT-D近似，离子与电子的相互作用可用超软赝势来描述，采用Broyden-Fletcher-Goldfarb-Shanno方案对结构进行了优化，平面波函数截断能设为400eV，在结构弛豫的过程中，能量收敛标准为5.0×10^-7eV/atom，单原子受力小于

原子位移的分量小于

应力小于0.02GPa。6. The method for constructing a two-dimensional Schottky heterojunction model based on germanene according to claim 1, wherein the calculation of the electronic properties of the Germanene/WSe₂ heterojunction model is based on density functional The first-principles CASTEP code of DFT is completed, implemented in Materials Studio software, using generalized gradient approximation GGA and functional PBE to handle electron exchange-related interactions, using Tkatchenko and Scheffler scheme to achieve DFT-D approximation, ion-electron approximation The interaction can be described by an ultrasoft pseudopotential. The Broyden-Fletcher-Goldfarb-Shanno scheme is used to optimize the structure. The cutoff energy of the plane wave function is set to 400eV. In the process of structure relaxation, the energy convergence criterion is 5.0×10^-7 eV/atom, the force on a single atom is less than

The component of atomic displacement is less than

The stress is less than 0.02GPa.7.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型的能带使用GGA-PBE形式的二维路径G(0 0 0)-M(0 0.50)-K(-0.333 -0.667 0)-G(0 0 0)，单层WSe₂是直接带隙，禁带宽度为1.532eV；价带顶VBM和导带底CBM位于K点；Germanene/WSe₂异质结模型是典型的肖特基异质结，形成p型肖特基接触，其中异质结中Germanene在K点处有一个小得几乎为零的带隙。7. The method for constructing a germanene-based two-dimensional Schottky heterojunction model according to claim 1, wherein the energy band of the Germanene/WSe₂ heterojunction model uses a GGA-PBE form of two Dimensional path G(0 0 0)-M(0 0.50)-K(-0.333 -0.667 0)-G(0 0 0), single-layer WSe₂ is a direct band gap with a forbidden band width of 1.532eV; the top of the valence band The VBM and conduction band bottom CBM are located at the K point; the Germanene/WSe₂ heterojunction model is a typical Schottky heterojunction, forming a p-type Schottky contact, in which the Germanene in the heterojunction has a small almost zero band gap.8.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型的界面间距为

带隙开口值10meV～45meV。8. The method for constructing a germanene-based two-dimensional Schottky heterojunction model according to claim 1, wherein the interfacial spacing of the Germanene/WSe₂ heterojunction model is

The band gap opening value is 10meV～45meV.9.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型中，金属Germanene和半导体单层WSe₂平衡层间距下Germanene/WSe₂异质结在Z方向的静电势，单层WSe₂比Germanene具有更深的电势，Germanene和WSe₂之间的静电电位差高达12.3eV；Germanene/WSe₂异质结模型保持了Germanene的高载流子迁移率。9. The method for constructing a germanene-based two-dimensional Schottky heterojunction model according to claim 1, wherein in the Germanene/WSe₂ heterojunction model, metal Germanene and semiconductor monolayer WSe₂ Electrostatic potential of Germanene/WSe₂ heterojunction in Z direction under balanced interlayer spacing, single-layer WSe₂ has a deeper potential than Germanene, and the electrostatic potential difference between Germanene and WSe₂ is as high as 12.3 eV; Germanene/WSe₂ heterojunction The model maintains the high carrier mobility of Germanene.10.根据权利要求1所述的基于锗烯的二维肖特基异质结模型的构建方法，其特征在于，所述Germanene/WSe₂异质结模型中，有效质量定义为：10. The method for constructing a germanene-based two-dimensional Schottky heterojunction model according to claim 1, wherein, in the Germanene/WSe₂ heterojunction model, the effective mass is defined as:

其中，k是波矢量，

是简化的普朗克常数，m是有效质量，E是能量。where k is the wave vector,

is the simplified Planck constant, m is the effective mass, and E is the energy.

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