CN109346131A - A kind of construction method of heterojunction device model - Google Patents
A kind of construction method of heterojunction device model Download PDFInfo
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- CN109346131A CN109346131A CN201811039157.XA CN201811039157A CN109346131A CN 109346131 A CN109346131 A CN 109346131A CN 201811039157 A CN201811039157 A CN 201811039157A CN 109346131 A CN109346131 A CN 109346131A
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Abstract
The invention discloses a kind of construction methods of heterojunction device model, comprising: chooses alkali metal M and chalcogen X and constructs decelerating transition metal chalcogenide M2X, alkali metal M and chalcogenide X-shaped are at M-X-M sandwich structure, then carry out structure optimization；M after selecting step (1) optimization2X architecture, calculate electronic structure, electron mobility, the absorption coefficient of light, top of valence band and conduction band bottom level of energy；Choose M ' X '2, for M ' selected from major element or transition metal, X ' is selected from major element, and formation X '-M '-X ' sandwich structure carries out structure optimization, and calculate the top of valence band level of energy and energy gap low with conduction band；By M2X and M ' X '2Expansion born of the same parents are carried out to stack to form heterojunction device model.The heterojunction device model of the construction method building provided through the invention has good photoelectron, hole separating capacity, provides research direction to develop and preparing electronic device and the photoelectric device of high mobility.
Description
Technical field
The invention belongs to low-dimensional device arts, in particular to a kind of construction method of heterojunction device model.
Background technique
Graphene is the two-dimensional material that single layer of carbon atom most thin, most hard, that conduction velocity of electrons is most fast is constituted, extensively
It is used to prepare the transparent conductive electrode of high speed device, solar cell.Further, held very much using several single layers or several layers of two-dimensional material
It easily carries out longitudinal (or lateral) to stack, unprecedented new material can be formed, this structure is known as Van der Waals by people
(vdW) hetero-junctions.Graphene just has electrically and thermally property well, so that it is in transparent conductor, high mobility field
There is very big application prospect on effect transistor.Although graphene has very high mobility (at room temperature, 10 at room temperature5cm2V- 1S-1), still, it does not have band gap, this makes it be difficult to apply to transistor or photoelectric device etc..Utilize graphene/boron nitride
Hetero-junctions successfully solves zero energy gap of graphene and can not form the short slab of " 0 ", " 1 " double states, opens the energy of graphene
Gap, and due to superperiod property, to form the odd number solutions such as different Morie fringes and secondary dirac cone.
TMDCs is that one kind has chemical general formula for MX2Lamellar compound, wherein M represents transition metal atoms, and X is represented
Sulfur family atom.Identical as graphene, TMDCs has layer structure, and each layer is attached also by van der waals force.It is each
A TMDC single layer is made of three atomic layers, wherein transition metal layer forms sandwich structure between two sulfur family atomic layers.
One of peculiar property that TMDCs has is to form different crystal many types of.
The discovery of two-dimentional transition metal chalcogenide (TMDCs) gives two-dimentional family to add many brilliance, while also making up
Graphene has zero band gap defect, such as has the field effect transistor of the 2H-MoS2 of band gap, compared to common GaAs/
AlGaAs transistor can effectively increase device integration although thickness has been very effectively thinned, its mobility is only
There are several hundred cm2V-1S-1, or even to be lower than silicon transistor.Meanwhile having the mobility of band gap TMDCs for other is often also several
Hundred cm2V-1S-1Magnitude, do not match in excellence or beauty the device (room temperature~5000cm that has been widely used2V-1S-1).Subsequent two-dimensional material work
There is the probing into of the two-dimensional material of anti-TMDCs structure (such as Ca again2N), but regrettably such material is the discovery that there is gold
Zero band gap of attribute.Therefore, in order to increase device integration, while retaining high mobility at room temperature again, for novel high migration
Rate has the exploration of the two-dimensional material of band gap to be of great significance.
The structure of molecule determines its property, in actual experimentation, is difficult to predict the rock-steady structure of molecule, need
By chemistry is calculated, in natural conditions, molecule mainly exists in the form of minimum energy, only the configuration ability of minimum energy
Representative, property could represent the property of institute's research system, but the model established in modeling process not necessarily has most
Low energy, so firstly the need of molecular configuration optimization is carried out, by the model optimization established to the minimal point of an energy.It can
Direction is provided using the design of material and exploitation by way of model construction as two-dimensional material and hetero-junctions.
Summary of the invention
The purpose of the present invention is to provide a kind of construction method of heterojunction device model, the building provided through the invention
The heterojunction device model of method building has good photoelectron, hole separating capacity, to develop and preparing high mobility
Electronic device and photoelectric device provide research direction.
A kind of construction method of heterojunction device model, comprising the following steps:
(1) it chooses alkali metal M and chalcogen X and constructs decelerating transition metal chalcogenide M2X, alkali metal M and sulfur family chemical combination
Object X-shaped is at M-X-M sandwich structure, then carries out structure optimization；
(2) M after selecting step (1) optimization2X architecture calculates electronic structure, electron mobility, the absorption coefficient of light, valence band
The level of energy on top and conduction band bottom；
(3) M ' X ' is chosen2, for M ' selected from major element or transition metal, X ' is selected from major element, formation Sanming City X '-M '-X '
Structure is controlled, carries out structure optimization, and calculate the top of valence band level of energy and energy gap low with conduction band；
(4) by the M in step (1)2M ' X ' in X and step (3)2Expansion born of the same parents are carried out to stack to form heterojunction device model.
In step (1), the alkali metal M is selected from one of Na, K, Rb or Cs, and chalcogen X is selected from O, S, Se
Or one of Te.
The structure of the decelerating transition metal chalcogenide (anti-TMDCs) is that metallic atom coats anion, metallic atom
It is 2:1 with anion element ratio, forms metal-anion-metal sandwich structure, with conventional transition metal chalcogenide gold
Belong to opposite with anion ratio 1:2.Alkali metal and its compound are widely studied applied to every field, and alkali metal feature is electronics
It is easy ionization and forms+1 valence ion, and sulfur family anion feature is that electronegativity is stronger, is easy to get and electronically forms -2 valence
The two is formed anti-TMDCs structure by ion, and the two-dimentional new material for possessing band gap for generation provides direction.
M in step (2), after optimization2The band gap of X architecture is 1~3eV, electron mobility is 19~18700cm2V-1S-1。
Preferably, in step (1), the decelerating transition metal chalcogenide M of building2The chemical formula of X is Na2O、Na2S、
Na2Se、Na2Te、K2S、Rb2S or Rb2Te。
The decelerating transition metal chalcogenide of above-mentioned element building, the band gap of the structure after optimization in visible-range, inhale by light
Receipts coefficient is big, and both direction electron mobility is sufficiently large.
M in step (2), after optimization2The band gap of X architecture is 1.9~3eV, electron mobility be 360~
18700cm2V-1S-1。
In step (3), M ' X '2Electron affinity it is higher, the M after optimization2X architecture not only has high light absorption system
Number, but also with high conduction band bottom and top of valence band energy level, therefore pass through the M ' X ' with biggish electron affinity2It can be formed
Second class hetero-junctions has good photoelectron, hole separating capacity.
Preferably, in step (3), the M ' X '2Selected from SnSe2、SnS2、PtS2、PtSe2Or two-dimensional layer transition gold
Belong to one of chalkogenide TMDCs.
Above-mentioned M ' X '2With M2X-shaped at the second class hetero-junctions have better photoelectron, hole separating capacity.
The present invention utilizes the excellent properties of two dvielements, constructs the anti-mistake with visible light bandgap and high electron mobility
Metal chalcogenide compound is crossed, the two-dimensional material for compensating for anti-TMDCs structure is zero band gap and the migration of the TMDCs that possesses band gap
Rate and not high disadvantage；And the second class heterojunction photoelectric device can be readily formed with the material of larger electron affinity.This
Invention provide construction method building heterojunction device model have good photoelectron, hole separating capacity, for exploitation and
The electronic device and photoelectric device for preparing high mobility provide direction.
Detailed description of the invention
Fig. 1 is the M of anti-TMDCs provided by the invention2The structural schematic diagram of X；
Fig. 2 is the Na that embodiment 1 provides2The band structure of O；
Fig. 3 is the Cs that embodiment 2 provides2The band structure of O；
Fig. 4 is the Na that embodiment 1 and embodiment 2 provide respectively2O and Cs2Absorption coefficient and silicon of the O in visible-range
Comparison diagram；
Fig. 5 is the M that embodiment 1 provides2X and SnSe2It is formed by the top view of the second class heterojunction structure；
Fig. 6 is the M that embodiment 1 provides2X and SnSe2It is formed by the side view of the second class heterojunction structure；
Fig. 7 is the Na that embodiment 1 provides2O and SnSe2It is formed by the conduction band valence band schematic diagram of the second class hetero-junctions；
Fig. 8 is the Cs that embodiment 2 provides2O and SnSe2It is formed by the conduction band valence band schematic diagram of the second class hetero-junctions.
Specific embodiment
The present invention is further illustrated below in conjunction with drawings and the specific embodiments.It should be understood, however, that these examples are only
It is that but should not be understood as specifically describing use in more detail for present invention is limited in any form.
Embodiment 1
1) anti-TMDCs two-dimensional material is chosen, M is Na element, and X is O element, then carries out structure Relaxation, and carry out crystalline substance
The fitting of lattice constant: the energy balane after taking different a=b lattice constants to optimize, fitting obtain optimum lattice constant:(direction z is vacuum)；
2) Na after step 1) optimization2O two-dimensional material carries out obtaining direct band from just calculating and obtaining the information such as energy band
Gap, effective mass, mobility, the absorption coefficient of light and conduction band valence band location；
3) a high electron affinity material SnSe is chosen2, structure optimization is carried out to it, and it is low with conduction band to calculate top of valence band
Level of energy and energy gap,(direction z is vacuum ), and calculate the top of valence band level of energy low with conduction band with
Energy gap；
4) structure by step 1) and 3), which carries out expansion born of the same parents' stacking, can form heterojunction device model (so that lattice mismatch is less than
5%).
In the present embodiment, anti-TMDCs structure as shown in Figure 1, wherein 1 be Na atom, 2 be O atom.
Monoatomic layer Na is carried out in step 2)2When the electronic structure of O is calculated and simulated, energy band as shown in Figure 2 is obtained
Figure, wherein M (0.5,0,0), Γ (0,0,0), K (1/3,1/3,0) respectively indicate the high symmetric points of first Brillouin-Zone, from Fig. 2
In it can be seen that Na2O is direct band-gap semicondictor.
As shown in figure 4, to Na2O carries out optical absorption coefficient calculating, as can be seen from Figure 4 has in visible-range
Biggish and absorption coefficient, in the case where there is most of visible light wave range, absorption coefficient is by the absorption coefficient of light than experimentally measuring silicon
It is big, illustrate the Na of the present embodiment building2O structure can be efficiently applied to the building of the second class heterojunction device model.
SnSe2With Na2The structural schematic diagram for the heterojunction device model that O is formed is as shown in Figure 5 and Figure 6, wherein 1 is former for Na
Son, 2 be O atom, and 3 be Sn atom, and 4 be Se atom.
As shown in fig. 7, by the obtained valence band of comparing calculation and conduction band positions, as can be seen from Figure 7 SnSe2With
Na2O forms the second class heterojunction device model, band curvature will occur in interface, because of Na2The valence band conduction level of O is all
Higher than SnSe2, so electronics will be by Na in non-photic situation2O is transferred to SnSe2, electrons and holes will be strapped in SnSe respectively2
And Na2O equally will be fettered effectively if it is photoexcitation, therefore have good photoelectron, hole separating capacity.
Embodiment 2
1) anti-TMDCs two-dimensional material is chosen, M is Cs element, and X is O element, then carries out structure Relaxation, and carry out crystalline substance
The fitting of lattice constant: the energy balane after taking different a=b lattice constants to optimize, fitting obtain optimum lattice constant:(direction z is vacuum)；
2) Cs after step 1) optimization2O two-dimensional material carries out obtaining direct band from just calculating and obtaining the information such as energy band
Gap, effective mass, mobility, the absorption coefficient of light, with conduction band valence band location；
3) high electron affinity material SnSe is chosen2, structure optimization is carried out to it, and calculate the top of valence band energy low with conduction band
Level position and energy gap,(direction z is vacuum), and calculate the top of valence band level of energy low with conduction band with
Energy gap；
4) structure by step 1) and 3), which carries out expansion born of the same parents' stacking, can form heterojunction device model (so that lattice mismatch is less than
5%).
In the present embodiment, monoatomic layer Cs is carried out in step 2)2When the electronic structure of O is calculated and simulated, obtain such as Fig. 3
Shown in energy band diagram, wherein M (0.5,0,0), Γ (0,0,0), K (1/3,1/3,0) respectively indicate first Brillouin-Zone height it is right
Claim point, as can be seen from Figure 3 Cs2O is indirect band-gap semiconductor.
As shown in figure 5, to Cs2O carries out optical absorption coefficient calculating, and discovery has biggish light absorption in visible-range
Coefficient, in the case where there is most of visible light wave range, absorption coefficient will be bigger than the absorption coefficient of light for experimentally measuring silicon, building
Cs2O structure can be efficiently applied to the building of the second class heterojunction device model.
As shown in figure 8, by the obtained valence band of comparing calculation and conduction band positions, SnSe2With Cs2It is heterogeneous that O forms the second class
In interface band curvature will occur for junction device model, because of Cs2The valence band conduction level of O is all higher than SnSe2, so non-photic
In the case of electronics will be by Cs2O is transferred to SnSe2, electrons and holes will be strapped in SnSe respectively2And Cs2O swashs if it is photic
Hair, equally will effectively fetter, therefore have good photoelectron, hole separating capacity.
Embodiment 3
If the anti-TMDCs that embodiment 1 constructs, M are K element, X is O element, with SnSe2Form the second class heterojunction device
Model.
Embodiment 4
The anti-TMDCs constructed such as embodiment 1 is Rb2O, with SnSe2Form the second class heterojunction device model.
Embodiment 5-16
Anti- TMDCs as embodiment 1 constructs is respectively Na2S、K2S、Rb2S、Cs2S、Na2Se、K2Se、Rb2Se、Cs2Se、
Na2Te、K2Te、Rb2Te、Cs2Te, with SnSe2Form the second class heterojunction device model.
Table 1-3 is respectively the M that embodiment 1-16 is constructed respectively2Mobility, effective mass and the band gap of X.Table 1,2 is to pass through
Simplation verification, the M being calculated2The conducting particles mobility and effective mass of X.
The M that 1 embodiment 1-16 of table is provided2X mobility
The M that 2 embodiment 1-16 of table is provided2X effective mass
The M that 3 embodiment 1-16 of table is provided2X band gap
Above-mentioned is the detailed statement for preferred embodiment, it is obvious that the research of technical field
The change that personnel can make form and content aspect unsubstantiality according to above-mentioned step is substantially protected without departing from the present invention
The range of shield, therefore, the present invention are not limited to above-mentioned specific form and details.
Claims (7)
1. a kind of construction method of heterojunction device model, comprising the following steps:
(1) it chooses alkali metal M and chalcogen X and constructs decelerating transition metal chalcogenide M2X, alkali metal M and chalcogenide X-shaped
At M-X-M sandwich structure, then carry out structure optimization；
(2) M after selecting step (1) optimization2X architecture, calculate electronic structure, electron mobility, the absorption coefficient of light, top of valence band with
The level of energy at conduction band bottom；
(3) M ' X ' is chosen2, for M ' selected from major element or transition metal, X ' is selected from major element, formation X '-M '-X ' sandwich knot
Structure carries out structure optimization, and calculates the top of valence band level of energy and energy gap low with conduction band；
(4) by the M in step (1)2M ' X ' in X and step (3)2Expansion born of the same parents are carried out to stack to form heterojunction device model.
2. the construction method of heterojunction device model according to claim 1, which is characterized in that described in step (1)
Alkali metal M be selected from one of Na, K, Rb or Cs, chalcogen X is selected from one of O, S, Se or Te.
3. the construction method of heterojunction device model according to claim 2, which is characterized in that in step (2), after optimization
M2The band gap of X architecture is 1~3eV, electron mobility is 19~18700cm2V-1S-1。
4. the construction method of heterojunction device model according to claim 1, which is characterized in that in step (1), building
Decelerating transition metal chalcogenide M2The chemical formula of X is Na2O、Na2S、Na2Se、Na2Te、K2S、Rb2S or Rb2Te。
5. the construction method of heterojunction device model according to claim 4, which is characterized in that in step (2), optimization
M afterwards2The band gap of X architecture is 1.9~3eV, electron mobility is 360~18700cm2V-1S-1。
6. the construction method of heterojunction device model according to claim 1, which is characterized in that described in step (3)
M ' X '2Selected from SnSe2、SnS2、PtS2、PtSe2Or one of two-dimensional layer transition metal chalcogenide TMDCs.
7. the construction method of heterojunction device model according to claim 1, which is characterized in that the M2X and M ' X '2
Expansion born of the same parents are carried out to stack to form the second class heterojunction device model, the M ' X '2Electron affinity be respectively greater than with work function
M2The electron affinity and work function of X.
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| CN111863625A (en) * | 2020-07-28 | 2020-10-30 | 哈尔滨工业大学 | Single-material PN heterojunction and design method thereof |
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| CN105742412A (en) * | 2016-04-28 | 2016-07-06 | 中国科学院上海微***与信息技术研究所 | Alkali metal doping method for thin-film solar cell absorption layer |
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