CN115292961A - Method for predicting carrier mobility of semiconductor - Google Patents

Abstract

The invention relates to a method for predicting the carrier mobility of a semiconductor, which comprises the steps of modeling a target crystal and calculating the carrier mobility, carrying out structural distortion on the target crystal by modeling and calculating a correction value, and correcting the calculation result of the carrier mobility by using the correction value. According to the invention, the crystal structure is distorted, the corrected value is calculated, and the target crystal carrier mobility is obtained based on the corrected value, so that the problem that the mobility of the calculated and predicted carrier is higher than the carrier mobility measured in experiments is solved, and the effects that the calculated and predicted result is more accurate and close to the actual situation are achieved.

Description

Method for Predicting Carrier Mobility in Semiconductors

technical field

The invention belongs to the field of semiconductors, and in particular relates to a method for predicting the mobility of semiconductor carriers and a method for screening semiconductor materials.

Background technique

A semiconductor is a material whose electrical conductivity is between that of a conductor and an insulator at room temperature. A semiconductor is a material with controllable conductivity, ranging from an insulator to a conductor. Optoelectronic materials refer to materials used to manufacture various optoelectronic devices, such as materials including various active and passive photoelectric sensors, optical information processing and storage devices, and optical communications; infrared materials, laser materials, optical fiber materials, nonlinear optical materials, etc. The carrier mobility of semiconductors and optoelectronic materials directly affects the performance of electronic devices, and people generally hope to obtain devices with high carrier mobility. Based on the first principles, the carrier mobility of semiconductors and optoelectronic materials can be calculated, and then the properties of optoelectronic materials can be predicted, and then materials can be screened and optoelectronic devices designed according to the required properties.

Carrier mobility usually refers to the overall movement speed of electrons and holes inside a semiconductor, and is an important physical quantity to measure the performance of semiconductor devices. Mobility affects two properties of semiconductors: one is to determine the conductivity (reciprocal of resistivity) of semiconductor materials together with carrier concentration. The larger the mobility, the smaller the resistivity, the smaller the power consumption and the larger the current carrying capacity when passing the same current. The second is to affect the operating frequency of the device. The main limitation of the frequency response characteristics of bipolar transistors is the time for minority carriers to transit the base region. The greater the mobility, the shorter the transition time required. The cut-off frequency of the transistor is proportional to the carrier mobility of the base material, so increasing the carrier mobility can reduce power consumption and improve the current carrying capacity of the device. At the same time, the switching speed of the transistor is increased.

At present, the carrier mobility of semiconductors and optoelectronic materials can be measured experimentally, and the carrier mobility can also be calculated and predicted by Boltzmann transport theory and deformation potential theory. However, the carrier mobility predicted by these theoretical calculations is higher than the experimentally measured carrier mobility. Therefore, researchers are committed to finding a carrier mobility prediction method to make the results more accurate and fit the actual situation. It is expected that through more accurate performance prediction, more suitable materials can be found and more sophisticated electronic devices can be designed.

Contents of the invention

In view of this, the present invention provides a method for predicting the mobility of semiconductor carriers and a method for screening semiconductor materials. These solutions solve the problem that carrier mobility predictions are often unrealistic, not accurate enough, and the materials that pass the prediction screening do not meet expectations.

In order to achieve the above object, according to an embodiment of the present invention, the present invention provides a method for predicting the carrier mobility of a semiconductor, by modeling the target crystal and calculating the carrier mobility, characterized in that the modeling includes The structure of the target crystal is distorted and a correction value is calculated, and the calculation result of the carrier mobility is corrected by using the correction value.

Optionally, the method includes the steps of:

Obtain the target crystal structure data file; calculate the carrier mobility influencing parameter of the target crystal according to the target crystal structure data file; distort the structure of the target crystal, and calculate the correction value; according to the carrier mobility influencing parameter and correction value , to obtain the target crystal carrier mobility.

Optionally, perform structural distortion on the target crystal, and calculate correction values, including:

Construct the original cell crystal file of the target crystal, and distort the structure of the original cell crystal file to obtain the distorted original cell crystal file;

Calculate the band gap of the original cell crystal file and the distorted original cell crystal file respectively, and obtain the original cell band gap and supercell band gap respectively;

Calculate the effective mass correction value based on the primary and supercellular band gaps.

的随机位移以扭曲晶格，得到扭曲原胞晶体文件。Optionally, construct the original cell crystal file of the target crystal, and distort the structure of the original cell crystal file to obtain the distorted original cell crystal file, including: construct the original cell crystal file of the target crystal; perform cell expansion on the original cell crystal file ; Apply greater than zero less than or equal to some or all atoms

to distort the lattice, resulting in a distorted cell crystal file.

Optionally, the effective mass correction value is calculated according to the primary cell band gap and the supercellular band gap, including:

According to the band gap of the original cell and the band gap of the supercell, through the effective mass k.p perturbation theory, calculate the corresponding effective mass of the band edge of the original cell and the effective mass of the band edge of the supercell; quality to get the effective quality correction value.

Optionally, according to the band gap of the primary cell and the band gap of the supercell, through the effective mass k.p perturbation theory, the corresponding effective mass of the band edge of the primary cell and the effective mass of the band edge of the supercell are calculated respectively, and the calculation formula of the effective mass of the band edge is :

是带边态|n0>的有效质量，0代表了带边所在位置的动量，m₀是自由电子的质量，E_n0-E_l0是带隙，|l0>是0处的其它本征态。in,

is the effective mass of the band edge state |n0>, 0 represents the momentum at the position of the band edge, m ₀ is the mass of free electrons, E _n0 -E _l0 is the band gap, and |l0> is the other eigenstates at 0.

Optionally, perform structural distortion on the target crystal, and calculate correction values, including:

Distort the structure of the original cell crystal of the target crystal to obtain the distorted original cell crystal; relax the structure of the distorted original cell crystal, calculate the self-consistency and calculate the density of states; compare the original cell crystal and the distorted original cell crystal, and calculate the correction value;

截断能设置为600eV；将弛豫后的CONTCAR作为静态计算和态密度计算的POSCAR；并且使KPOINTS文件中k点密度与原胞晶体的k点密度相同。Among them, VASP software is used to perform structural relaxation on distorted protocellular crystals. PBE (Perdew-Burke-Ernzerhof) exchange-correlation functional is used for relaxation, and the convergence criteria of energy and force are 1×10 ^-6 eV and

The cut-off energy is set to 600eV; the relaxed CONTCAR is used as POSCAR for static calculation and density of state calculation; and the k-point density in the KPOINTS file is the same as that of the original cell crystal.

Optionally, calculating the carrier mobility influencing parameters of the crystal according to the crystal structure data file includes: performing structural optimization on the crystal structure data file; calculating the effective mass, elastic constant and deformation potential of the crystal.

Optionally, according to the carrier mobility influencing parameters and correction values, the target crystal carrier mobility is obtained, including:

Put the effective mass, elastic constant and deformation potential into the following formula, and multiply by the correction value to obtain the target crystal carrier mobility μ;

是约化的普朗克常数；m^*是扭曲修正有效质量，D₁是形变势，C_ii是弹性常数。where e is the electron charge, k _B is Boltzmann's constant, T is the temperature,

is the reduced Planck constant; m ^* is the twist-corrected effective mass, D ₁ is the deformation potential, and C _ii is the elastic constant.

Alternatively, the effective mass of the crystal is calculated by:

是约化的普朗克常数，m^*是电子或者空穴的有效质量，k是波矢，E(k)能带取值通过对晶体结构数据文件进行计算得到，采用PBE(Perdew-Burke-Ernzerhof)交换关联泛函；并设置能量和力的收敛标准分别为1×10^-6eV和

截断能设置为600eV。in

is the reduced Planck constant, m ^* is the effective mass of electrons or holes, k is the wave vector, and the energy band value of E(k) is obtained by calculating the crystal structure data file, using PBE (Perdew-Burke- Ernzerhof) exchange-correlation functional; and set the convergence criteria of energy and force as 1×10 ^-6 eV and

The cutoff energy was set to 600eV.

In order to achieve the above object, according to an embodiment of the present invention, the present invention also provides a method for screening semiconductor materials, which is predicted by the method of predicting the mobility of semiconductor carriers as described above, and screened according to the mobility of semiconductor carriers .

Beneficial effects of the present invention:

The inventors found that the existing calculation method leads to a higher predicted value than the actual value, because the crystal will be distorted in reality, and the local distortion of the crystal destroys the spatial symmetry of the original crystal, which will lead to an increase in the band gap. However, the existing calculation method does not take this into consideration. Therefore, the inventors distorted the crystal structure and calculated the correction value to simulate a situation that is closer to reality; then according to the carrier mobility affecting parameters and correction value, the Target crystal carrier mobility. Because the change of carrier mobility is taken into account by correcting the lattice distortion, so the calculation and prediction results are more accurate and close to the actual situation.

Description of drawings

Figure 1: E _vbm -E _1s of CsPbCl ₃ perovskite materials as a function of stress;

Figure 2: E _cbm -E _1s of CsPbCl ₃ perovskite materials as a function of stress;

Figure 3: Comparison of the density of states calculated by the 2x2x2 twisted supercell and the original cell of CsPbCl ₃ ;

Figure 4: Flowchart of _CsPbCl crystal carrier mobility prediction.

Detailed ways

The examples given are for better description of the present invention, but the content of the present invention is not limited to the examples given. Therefore, non-essential improvements and adjustments to the implementation by those skilled in the art based on the content of the invention above still fall within the protection scope of the present invention.

Hereinafter, the present application will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be carried out in many different ways and is not limited to the specific exemplary embodiments described herein.

Objects and advantages of exemplary embodiments of the present invention will be understood and made more apparent with reference to the description hereinafter, but the objects and advantages of exemplary embodiments of the present invention are not Not limited to the description below. In the description of the exemplary embodiments, detailed explanations of prior art are omitted when it is considered that they may unnecessarily obscure the gist of the invention.

Embodiment one

Explanation of the basic principles:

In this example, the carrier mobility is calculated by using the deformation potential theory as an example. The deformation potential theory is based on the scattering of electrons and acoustic phonons. It believes that lattice vibration will change the potential of the crystal, and the change of potential The carriers will scatter in different states, and the carrier mobility μ can be simplified to the following formula to calculate:

是约化的普朗克常数。从上面的公式可以看出除了一些常数之外，计算载流子的迁移率需要分别计算材料的有效质量m^*、形变势D₁和弹性常数C_ii三个物理量。通过第一性原理，可以从半导体的晶体结构、能带结构计算上述的三个物理量以及载流子迁移率。where e is the electron charge, k _B is Boltzmann's constant, T is the temperature,

is the reduced Planck constant. It can be seen from the above formula that in addition to some constants, the calculation of the carrier mobility requires the calculation of three physical quantities, the effective mass m ^* of the material, the deformation potential D ₁ and the elastic constant C _ii respectively. Through first principles, the above three physical quantities and carrier mobility can be calculated from the crystal structure and energy band structure of semiconductors.

Among them, we can usually calculate the effective mass m ^* through the energy band structure of the crystal. The energy band structure means that when atoms form molecules and even form three-dimensional structures, atomic orbitals will interact to generate orbitals with isolated energy levels. Three-dimensional The energy band structure of the material, and the method of taking the k-point along the direction of the high symmetry line in the Brillouin zone.

When the energy band structure of a crystal is known, the following formula can be used to calculate the effective mass of its electrons and holes:

是约化的普朗克常数，m^*是电子或者空穴的有效质量，E(k)是计算得到的能带，k是波矢。in

is the reduced Planck constant, m ^* is the effective mass of the electron or hole, E(k) is the calculated energy band, and k is the wave vector.

But in reality, the crystal will be distorted in reality, and the local distortion of the crystal destroys the spatial symmetry of the original crystal, so that the energy band structure changes, specifically, this will lead to an increase in the band gap (the band gap refers to the phase Two adjacent energy bands can be connected, overlapped, or separated, and a band gap will appear when the energy bands are separated), and the increase of the band gap will increase the effective mass of the band edge. Therefore, the inventor calculated the correction value of the effective mass by simulating the distortion of the crystal, and then calculated the mobility of the carriers through the above formula through the three physical quantities of the corrected effective mass m ^* , deformation potential D ₁ and elastic constant C _ii μ; In addition, the correction value of the overall carrier mobility can also be directly calculated through the correction value of the effective mass, and then the carrier mobility can be corrected.

And these related calculations can be done by manual, processor, computer and other methods, and various software and programs can also be used to assist the calculation. For example, the full name of VASP, ViennaAb-initio Simulation Package, is currently one of the most popular software in material simulation and computational material science research. It can deal with atoms, molecules, clusters, nanowires (or tubes), thin films, crystals, quasicrystals and amorphous materials, as well as surface systems and solids, calculate the structural parameters and configuration of materials, calculate the state equation and mechanics of materials Properties (bulk modulus and elastic constants), electronic structures of calculated materials (energy levels, charge density distribution, energy bands, electronic density of states), optical properties, magnetic properties, lattice dynamics properties and molecular dynamics of calculated materials learning simulation.

Specifically, as shown in Figure 4, taking the perovskite optoelectronic material CsPbCl ₃ of No. 221 space group (Pm-3m) as an example, the prediction and calculation process of carrier mobility, especially the acoustic phonon Scattering corrections.

Step S1: Use the Materials Project crystal database to obtain the CsPbCl ₃ crystal structure file, and convert the structure data file into a .vasp file with the help of VESTA software.

Step S2: Set VASP structure calculation parameter files, including calculation function setting file (INCAR), crystal system coordinate file (POSCAR), pseudopotential file (POTCAR) and reciprocal vector space description file (KPOINTS).

截断能设置为600eV。Step S3: Based on the parameters set in step S2, use VASP software to perform structural optimization, self-consistent calculation and energy band structure calculation on the obtained CsPbCl ₃ crystal structure. During the calculation process, the more efficient Perdew-Burke-Ernzerhof (PBE) The exchange-correlation functional does not take into account the spin-orbit coupling (SOC). And we set the convergence criteria for energy and force to be 1×10 ^-6 eV and

The cutoff energy was set to 600eV.

After calculating the energy band of space group _CsPbCl 221, the effective masses of electrons and holes can be calculated by the following formula:

是约化的普朗克常数，m^*是电子或者空穴的有效质量，E(k)是计算得到的能带，k是波矢。我们研究的是沿着CsPbCl₃[100]晶向方向的迁移率，而CsPbCl₃的价带顶和导带底均在布里渊区高对称的R(0.5,0.5,0.5)点，因此需要选择布里渊区高对称线R-M(0.5,0.5,0)来计算其迁移率。in

is the reduced Planck constant, m ^* is the effective mass of the electron or hole, E(k) is the calculated energy band, and k is the wave vector. What we study is the mobility along the CsPbCl ₃ [100] crystal direction, and the valence band top and conduction band bottom of CsPbCl ₃ are both at the R(0.5,0.5,0.5) point with high symmetry in the Brillouin zone, so we need Select the high symmetry line RM(0.5,0.5,0) in the Brillouin zone to calculate its mobility.

截断能设置为600eV。Step S4: Using VASP software to calculate the elastic constant of the optimized CsPbCl ₃ crystal. The PBE exchange-correlation functional is used in the calculation process, and the spin-orbit coupling (SOC) is not considered. And we set the convergence criteria for energy and force to be 1×10 ^-6 eV and

The cutoff energy was set to 600eV.

When calculating the elastic constants of CsPbCl ₃ crystals, it should be noted that CsPbCl ₃ in space group 221 belongs to the cubic phase, which has three independent elastic constants, namely: C ₁₁ , C ₁₂ and C ₄₄ , which can be determined by setting IBRION= in INCAR 6, and the mobility along the [100] orientation is: C _ii =C ₁₁ .

截断能设置为600eV。Step S5: Using VASP software to calculate the deformation potential of the CsPbCl ₃ crystal after structure optimization. The PBE exchange-correlation functional is used in the calculation process, and the spin-orbit coupling (SOC) is not considered. And we set the convergence criteria for energy and force to be 1×10 ^-6 eV and

The cutoff energy was set to 600eV.

When calculating the deformation potential of CsPbCl ₃ crystal, it is necessary to apply strains of Δa ₀ /a ₀ = -0.01, -0.005, 0, 0.005 and 0.01 on the lattice constant along the x direction, and then draw the conduction band bottom (CBM) and Figure 1 shows the relationship between energy E _cbm and E _{vbm of} the top of the valence band ( _VBM ) with stress. lattice constant. When discussing the energy movement of CBM and VBM under stress, we choose the 1s energy level E1s of halogen elements as the reference energy, and then discuss the relationship between E _cbm -E _1s and E _vbm -E _1s with stress, see Figure 1 and Figure 2. Figure 1 is a diagram of the relationship between E _cbm -E _1s of CsPbCl ₃ perovskite material and strain, and Figure 2 is a diagram of the relationship of E _vbm -E _1s of CsPbCl ₃ perovskite material with strain. Through fitting, the obtained deformation potentials of the bottom of the conduction band and the top of the valence band are: D _1c =7.37eV and D _1v =5.44eV, respectively.

的微小位移达到扭曲晶格的效果，以破坏其原有的221号空间群的对称性。该微小位移为随机位移(方向不一致)，而小于等于

的位移是为了在能使得晶体的扭曲前提下，又不破坏晶体本身的化学键，从而维持晶体结构又模拟了晶体的扭曲。Step S6: Using VASPKIT software to construct a 2x2x2 CsPbCl ₃ supercell, and distorting its structure. When constructing, we expand the cell first, and the expanded 2x2x2 CsPbCl ₃ supercell has 40 atoms, and then applies a

The slight displacement of the crystal lattice can achieve the effect of distorting the lattice, so as to destroy the symmetry of its original space group 221. The small displacement is a random displacement (inconsistent direction), and less than or equal to

The displacement is to maintain the crystal structure and simulate the distortion of the crystal without destroying the chemical bonds of the crystal itself under the premise of distorting the crystal.

截断能设置为600eV。将弛豫后的CONTCAR作为静态计算和态密度计算的POSCAR，在用VASP进行态密度计算时，为了和原胞计算的结果进行对比，KPOINTS文件中k点密度应该与原胞计算的密度保持相同。Step S7: Structural relaxation, self-consistent calculation and calculation of density of states are performed on the constructed twisted 2x2x2 CsPbCl ₃ supercell, and the spin-orbit coupling is not considered in the calculation process. Using VASP software, the distorted 2x2x2 CsPbCl ₃ supercell was first structurally relaxed, and the PBE exchange-correlation functional with higher calculation efficiency was used in the relaxation, and the convergence criteria of energy and force were 1×10 ^-6 eV and

The cutoff energy was set to 600eV. Use the relaxed CONTCAR as POSCAR for static calculation and density of state calculation. When using VASP to calculate the density of state, in order to compare with the results of the original cell calculation, the k-point density in the KPOINTS file should be the same as the density calculated by the original cell. .

Step S8: By comparing the band gap calculated with the twisted 2x2x2 CsPbCl ₃ supercell and the band gap calculated with the CsPbCl ₃ primitive cell, the increase in the effective mass of the twisted CsPbCl ₃ material is obtained, and further determined by the aforementioned carrier mobility μ The calculation formula of , was corrected to consider the mobility of the CsPbCl3 _perovskite material after twisting.

Specifically, the distorted bandgap is obtained from the density of states calculated by the supercell, and compared with the bandgap calculated by the original cell, the result of the enhanced bandgap of CsPbCl ₃ after the lattice distortion is obtained. According to the effective mass kp perturbation theory, the effective mass of the band edge of semiconductor material can be expressed as:

是半导体带边态|n0>的有效质量，0代表了带边所在位置的动量，m₀是自由电子的质量，E_n0-E_l0是半导体带隙，|l0>是0处的其它本征态。从上面的表达式可以看出，半导体带隙E_n0-E_l0的增加将会使带边有效质量

的增加，因此这也是我们修正有效质量的基础。我们的计算结果表明，扭曲后CsPbCl₃超胞的带隙比CsPbCl₃原胞的带隙更大，如下图3所示，图3(图中左向箭头标识线为超胞，而右向箭头标识线为原胞)：CsPbCl₃材料分别用2x2x2扭曲超胞和原胞计算出来的态密度(DOS)对比图。从图中可以看到，扭曲超胞计算出来的带隙比原胞要大，带隙大约从2.19eV增加到2.55eV。因此，修正后带隙大约增加了1.164倍，相应地有效质量也增加了1.164倍(此值为有效质量修正值)，修正后迁移率降低为原来的1/1.1645/2＝0.684(此值即为整体的修正系数)，即可以通过计算修正有效质量然后将修正后的有效质量带入载流子迁移率计算式中，也可以先计算出迁移率后，再乘以整体的修正系数。in

is the effective mass of the semiconductor band edge state |n0>, 0 represents the momentum at the position of the band edge, m ₀ is the mass of free electrons, E _n0 -E _l0 is the semiconductor band gap, |l0> is other eigenvalues at 0 state. It can be seen from the above expression that the increase of the semiconductor band gap E _n0 -E _l0 will make the band edge effective mass

Therefore, this is also the basis for us to correct the effective mass. Our calculation results show that the band gap of the distorted CsPbCl ₃ supercell is larger than that of the original CsPbCl ₃ cell, as shown in Fig. The marked line is the original cell): the comparison diagram of the density of states (DOS) calculated by the 2x2x2 twisted supercell and the original cell of the CsPbCl ₃ material. It can be seen from the figure that the calculated band gap of the twisted supercell is larger than that of the original cell, and the band gap increases from about 2.19eV to 2.55eV. Therefore, after the correction, the band gap increases by about 1.164 times, and accordingly the effective mass also increases by 1.164 times (this value is the correction value of the effective mass), and the mobility after correction is reduced to the original 1/1.1645/2=0.684 (this value is is the overall correction coefficient), that is, the effective mass can be corrected by calculating and then brought into the carrier mobility calculation formula, or the mobility can be calculated first, and then multiplied by the overall correction coefficient.

It is worth noting that the steps with labels such as S1-S8 do not indicate the execution order of the present invention, as long as they do not affect the effect of the invention, they can be implemented at the same time or adjusted sequentially; in addition, the specific implementation mentioned above There are all possible implementation modes that can be replaced by those skilled in the art without creative work, and each step of these implementation modes can be combined or combined with each other on the premise that the purpose of the present invention can be realized, and should also be described in within the protection scope of the rights of the present invention.

Embodiment two

This embodiment takes the calculation of electrical conductivity as an example to illustrate that various performance parameters of semiconductors can be further calculated and predicted through the predicted carrier mobility.

That is, after the carrier mobility is obtained through the above steps, various performance parameters of the semiconductor can be calculated by formulas.

For example, the formula for hole conductivity is:

Among them, μ _p is the hole carrier mobility; p is the hole concentration, and e is the electronic charge.

For n-type semiconductors:

Among them, μ _n is the carrier mobility; n is the electron concentration, and e is the electron charge. When there are two kinds of carriers conducting electricity in a semiconductor at the same time, the conductivity is the sum of the two.

Embodiment three

This embodiment takes the screening of semiconductor materials as an example, according to the parameter range required by electronic devices for semiconductor materials, such as the minimum carrier mobility requirement to achieve a certain function, and then according to the crystal structure model data provided by materials project and other crystal data , through the above predictions, properties such as carrier mobility, electrical conductivity, and work efficiency are obtained, and possible applicable materials are screened out, and finally electronic components are made.

For example, for bipolar transistors, high carrier mobility can shorten the time for carriers to cross the base region, increase the characteristic frequency (f _T ), and improve the frequency, speed and noise of the device. and other performance. Therefore, for bipolar transistors, it is necessary to screen semiconductor materials with higher carrier mobility.

For field effect transistors, enhancing the carrier mobility μ in the channel has the same effect as shortening the channel length L, which can improve the driving capability of the device, thereby increasing the working speed of the device. Therefore, for field effect transistors, it is necessary to screen semiconductor materials with higher carrier mobility.

For increasing the speed of large-scale integrated circuits, the delay time τ _d of signal transmission in the integrated circuit is inversely proportional to the logic voltage swing V _m of the signal and the carrier mobility μ. In order to ensure that the integrated circuit can work stably without being affected by heat, the logic voltage swing should be appropriately reduced; but at the same time, in order to ensure that the integrated circuit has a higher operating speed, it is only necessary to increase Mobility to shorten the delay time of signal transmission. Therefore, ultra-high-speed field-effect logic integrated circuits must have high carrier mobility to be realized.

For CMOS, the basic device of ULSI, it is more important to enhance the mobility of carriers, especially the mobility of holes. Since the mobility of holes in Si is about 2.5 times smaller than that of electrons, there are two major problems in Si- _CMOS technology: First, when designing CMOS, in order to ensure the consistency of current passing through PMOSFET and NMOSFET, it is necessary to Increasing the gate width of the PMOSFET by 2.5 times will inevitably lead to an increase in the chip area; second, the maximum operating frequency and speed of the Si- _CMOS device and its circuit will be limited by the performance of the PMOSFET. Therefore, in the development of radio frequency In CMOS integrated circuits and very large-scale CMOS integrated circuits, the semiconductor properties that need to be screened are higher hole mobility.

The above does not list all possible applications.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. A method for predicting the carrier mobility of a semiconductor, by modeling the target crystal and calculating the carrier mobility, characterized in that modeling includes distorting the structure of the target crystal and calculating a correction value, using the correction value The calculation results of carrier mobility were corrected. 2. the method for predicting semiconductor carrier mobility as claimed in claim 1, is characterized in that, comprises the steps: Obtain the target crystal structure data file; Calculating the carrier mobility influencing parameters of the target crystal according to the target crystal structure data file; Distort the structure of the target crystal and calculate the correction value; According to the carrier mobility influencing parameters and correction values, the target crystal carrier mobility is obtained. 3. the method for predicting semiconductor carrier mobility as claimed in claim 2, is characterized in that, carrying out structural distortion to target crystal, calculates correction value, comprises: Construct the original cell crystal file of the target crystal, and distort the structure of the original cell crystal file to obtain the distorted original cell crystal file; Calculate the band gap of the original cell crystal file and the distorted original cell crystal file respectively, and obtain the original cell band gap and supercell band gap respectively; Calculate the effective mass correction value based on the primary and supercellular band gaps. 4. the method for predicting semiconductor carrier mobility as claimed in claim 3, is characterized in that, constructs the original cell crystal file of target crystal, and carries out structural distortion to original cell crystal file, obtains twisted original cell crystal file, comprises: Construct the original cell crystal file of the target crystal; Carry out cell expansion processing on the original cell crystal file; Apply greater than zero less than or equal to atoms

to distort the lattice, resulting in a distorted cell crystal file. 5. the method for predicting semiconductor carrier mobility as claimed in claim 3, is characterized in that, according to original cell bandgap and supercell bandgap, calculates effective mass correction value, comprises: According to the band gap of the primary cell and the band gap of the supercell, through the effective mass k.p perturbation theory, the corresponding effective mass of the band edge of the primary cell and the effective mass of the band edge of the supercell are calculated respectively; The calculation formula of the band-edge effective mass is as follows

in,

is the effective mass of the band edge state |n0>, 0 represents the momentum at the position of the band edge, m ₀ is the mass of free electrons, E _n0 -E _l0 is the band gap, |l0> is other eigenstates at 0; According to the band-edge effective mass of the primary cell and the band-edge effective mass of the supercell, the corrected value of the effective mass is obtained. 6. The method for predicting the carrier mobility of a semiconductor according to any one of claims 2-5, wherein the target crystal is subjected to structural distortion, and the correction value is calculated, including: Distort the structure of the original cell crystal of the target crystal to obtain the twisted original cell crystal; Relaxation, self-consistent calculations and density of states calculations for distorted cell crystal structures; Comparing the original cell crystal and the distorted original cell crystal, calculate the correction value; Among them, VASP software is used to perform structural relaxation on distorted protocellular crystals. PBE (Perdew-Burke-Ernzerhof) exchange-correlation functional is used for relaxation, and the convergence criteria of energy and force are 1×10 ^-6 eV and

The cut-off energy is set to 600eV; the relaxed CONTCAR is used as POSCAR for static calculation and density of state calculation; and the k-point density in the KPOINTS file is the same as that of the original cell crystal. 7. the method for predicting semiconductor carrier mobility as claimed in claim 2, is characterized in that, according to described crystal structure data file, calculates the carrier mobility influence parameter of crystal, comprises: performing structural optimization on the crystal structure data file; Calculate the effective mass, elastic constant, and deformation potential of the crystal. 8. The method for predicting semiconductor carrier mobility as claimed in claim 7, is characterized in that, according to carrier mobility influence parameter, correction value, obtain target crystal carrier mobility, comprising: Put the effective mass, elastic constant and deformation potential into the following formula, and multiply by the correction value to obtain the target crystal carrier mobility μ;

where e is the electron charge, k _B is Boltzmann's constant, T is the temperature,

is the reduced Planck constant; m ^* is the twist-corrected effective mass, D ₁ is the deformation potential, and C _ii is the elastic constant. 9. predict the method for semiconductor carrier mobility as claimed in claim 8, it is characterized in that, the effective mass of crystal is calculated by following formula:

in

is the reduced Planck constant, m ^* is the effective mass of electrons or holes, k is the wave vector, and the energy band value of E(k) is obtained by calculating the crystal structure data file, using PBE (Perdew-Burke- Ernzerhof) exchange-correlation functional; and set the convergence criteria of energy and force as 1×10 ^-6 eV and

The cutoff energy was set to 600eV. 10. A method for screening semiconductor materials, characterized in that the prediction is performed by the method for predicting the mobility of semiconductor carriers according to any one of claims 1-9, and the screening is performed according to the mobility of semiconductor carriers.

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