Ultrasoft Pseudopotential Plane Wave Research Articles

First-principles calculations to investigate “H” and “K” doped RbSrF3 for photovoltaic applications

A cubic perovskite RbSrF3 structure has been doped with hydrogen and potassium, and their comparative study was carried out for the structural, electronic, and optical parameters. Self-consistent computation of ultra-soft pseudopotential plane-wave along with generalized gradient approximation (GGA) with Perdew Burke Ehrenzorf (GGA-PBE) exchange-correlation potential under the first principle is used for the computation of properties. Evaluated optimized lattice constant for Pm3m supercell is in good agreement with the already reported results and the bandgap reduces to a desired value for the “K” and “H” doping concentrations from 0% to 0.55%, this reduction is useful for water splitting and photovoltaic applications. The localized electrons for different bands are explained by DOS and PDOS. The optical properties for pure and H, K doped RbSrF3 have been recognized by allocating the maximas obtained after calculations. This was the first-ever comparative theoretical study of this type for RbSrF3 compound with the potassium and hydrogen dopants as far as our knowledge.

First-principles calculations to investigate the effect of Cs-doping in BaTiO3 for water-splitting application

The structural, electronic, and optical properties of the pure and Cs-doped BaTiO3 are investigated theoretically with the help of Cambridge Serial Total Energy Package code, which utilizes an ultra-soft pseudopotential plane wave and a Perdew Burke Ernzerhof exchange-correlation functional of the Generalized Gradient Approximation. The DFT + U approximation is employed to get the better results for electronic properties. The calculated lattice parameters and bandgap for pure BaTiO3 are found 4.034 Å and 2.513 eV which are consistent with the previous studies. The pure BaTiO3 possesses an indirect while the Cs-doped BaTiO3 systems have a direct band gap. The value of band gap is found 1.858, 2.103 and 1.882 eV for 0.13, 0.26 and 0.39% Cs-doped BaTiO3, respectively. For pure BaTiO3, the absorption edge is in the invisible region, whereas, the Cs-doped (0.13%) BaTiO3 possesses the maximum absorption edge in the visible region. By introducing the new Cs-3p states into the valence band of BaTiO3, the photocatalytic activity of the material is enhanced. For 0.26 and 0.39% Cs-doped BaTiO3, the absorption edge in the visible region is found lower than that of 0.13% Cs-doped BaTiO3. Moreover, 0.13% Cs-doped BaTiO3 possesses a minimal energy loss than that of 0.26 and 0.39% Cs-doped BaTiO3. Therefore, 0.13% Cs-doped BaTiO3 is found an efficient candidate for photocatalytic water-splitting by studying the combined effect of electronic and optical properties.

First-principles calculations to investigate variation in the bandgap of NaSrF3 Fluoro-Perovskite with external static isotropic pressure and its Impact on optical properties

The theoretical investigation of NaSrF3 fluoro-perovskite is carried out using ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange–correlation functional of Generalized Gradient Approximation (GGA) with the help of the density functional theory-based Cambridge Serial Total Energy Package (CASTEP) code. All the properties are investigated under the effect of external static isotropic pressure ranging from 0 to 100 GPa and 300 GPa. The lattice parameters of the material are decreased with the increment of the external pressure. The value of band gap is found 4.328, 2.795, and 0 eV at 0, 100 and 300 GPa, respectively. The optical properties of the material i.e., absorption, reflectivity, dielectric function, refractive index, conductivity, and loss function are also investigated. The static values of ε1 (ω) and n (ω) increase with the increase in pressure. It is resulted from the optical properties that the material has a high refractive index, absorption, and conductivity, and thus it is applicable in different photovoltaic systems like data storage media, and photonic crystals. Furthermore, the electronic properties of the material indicate that it operates as a semiconductor at 0 to 100 GPa while it acts as a conductor at 300 GPa.

First-principles study of calcium-based sulfur fixers and their products

Calcium-based sulfur-fixing agent, as the main sulfur-fixing product, is widely used in power plant boiler systems. In order to further study the thermodynamic properties and reaction characteristics of calcium-based sulfur fixing agent and its products, the method of combining power plant experiment with theory was used. The electronic structure, thermodynamic properties and density of states of quicklime, limestone, calcium sulfate (CaSO4) and calcium sulphoaluminate have been calculated based on the first-principles ultra-soft pseudopotential plane wave method of density functional theory. The generalized gradient approximation algorithm is used to optimize the structure of various minerals to achieve the most stable state. The results show that the enthalpy, entropy, specific heat capacity at constant pressure and Gibbs free energy of calcium sulfonate vary greatly from 25-1000 K, while the change of calcium oxide (CaO) is small, and that of calcium carbonate (CaCO3) and CaSO4 are between them. It shows that calcium sulphoaluminate has strong stability and more energy is needed to destroy the molecular structure of calcium sulphoaluminate. The CaO is the most unstable and requires less energy to react. The CaCO3 and CaSO4 are in between. The variation range of CaSO4 is greater than that of CaCO3, indicating that the stability of CaSO4 is higher than that of CaCO3. The experimental results show that the desulfurization efficiency of generating calcium sulphoaluminate is much higher than that of only generating CaSO4, indicating that calcium sulphoaluminate is very stable, which is consistent with the calculated results.

First-principles calculations to investigate ultra-wide bandgap semiconductor behavior of NaMgF3 fluoro-perovskite with external static isotropic pressure and its impact on optical properties

The structural, electronic, and optical properties of cubic fluoro-perovskite NaMgF3 were investigated theoretically at pressures ranging from 0 to 100 GPa with a 10-step escalation, i.e., 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 GPa. The research is conducted by using density functional theory (DFT) based CASTEP (Cambridge Serial Total Energy Package) code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange-correlation functional of Generalized Gradient Approximation (GGA). The band gap is found to be increasing from 5.749 to 8.723 eV when the pressure is increased from 0 to 100 GPa. The nature of the band gap remained indirect whether the pressure was applied or not. A significant increment was found in the band gap till 40 GPa as compared to higher pressure. Under the effect of pressures ranging from 0 to 100 GPa, several optical properties like the refractive index, loss function, reflectivity, and absorption coefficient have also been determined. The main peaks of dielectric function (real and imaginary), reflectivity, loss function, and refractive index (n) are observed to move towards higher values of energy with increasing pressure. A material that has a high optical conductivity, absorption, and refractive index is ideal for photovoltaic applications. Other optical technologies that use such material include waveguides, data storage medium, and photonic crystals.

Density function theory on the electronic structure property of anatase TiO2 doped by N or C with different percents

Formation energy, crystal structure and electronic structure of C, N doped anatase TiO2 are calculated based on the density functional theory of plane-wave ultrasoft pseudopotential. Results indicate that, due to doping of the C or N atoms in anatase TiO2, the lattice distorts obviously. The substitution of C tends to Ti site while N tends to O site. All the substitutions lead to the red shift of the optical absorption and increasing coefficient of light absorption. When N concentrations are 2.08% and 3.13% in N-doped TiO2, the highest photocatalytic activity is obtained, while it is 2.08% for C-doped one.

Static isotropic pressure induced ultra-wide band gap response of NaCaF3 fluoro-perovskite and its repercussions on optical properties: ab initio calculation

ABSTRACT A comprehensive theoretical study to investigate the outcomes of externally applied static isotropic pressure (0–50 GPa) on electronic, optical and structural properties of NaCaF3, using density functional theory based CASTEP code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof exchange–correlation functional of Generalized Gradient Approximation, is reported. The electronic band gap shows the increasing trend 4.773–6.203 eV with increasing external pressure. The increase in band gap is significant up to 20 GPa as compared to higher external pressures. The mystery of increasing band gap is nicely decoded by the total density of states and elemental partial density of states. Optical properties have been calculated to analyse the impact of increment in band gap on them. We observed that the highest peak of energy loss function shows the blue shift which confirms the increment of band gap. At zero photon energy, for 0 GPa, the static refractive index has a value of 1.4456. After applying external pressure, there is a slight increase in which favours the ultrawide band gap behaviour of the ternary compound. The energy points at which the absorption peak is maxima, the refractive index has lowest value.

Structural, electronics and optical properties of sodium based fluoroperovskites NaXF3 (X = Ca, Mg, Sr and Zn): First principles calculations

A theoretical study to investigate the electronic, optical and structural properties of sodium-based cubic fluoro-perovskite NaXF3 (where X = Ca, Mg, Sr, Zn), using density functional theory (DFT) based CASTEP (Cambridge Serial Total Energy Package) code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange-correlation functional of Generalized Gradient Approximation (GGA), is reported. All of these compounds are found to be in a stable shape with a cubic pm3m structure, according to the findings. The results we discovered are consistent with the data that is already available. Calculations of the electronic band structure show that NaCaF3, NaMgF3 and NaSrF3 have a direct and NaZnF3 has an indirect band gap. Partial density of states (PDOS) and total density of states (TDOS) confirm the degree of electron localization in various bands. All four compounds' optical transitions were investigated by fitting the dispersion relation for the hypothetical dielectric function scale to the corresponding peaks. NaZnF3 is semiconductor while the NaCF3, NaMgF3 and NaSrF3 compounds have insulating behavior. The hypothetical part dispersion of the dielectric function reveals its wide range of energy transparency. As a result, it's possible that these materials may be used in optoelectronics to absorb ultraviolet light.

First-principles calculations to investigate structural, electronic and optical properties of Na based fluoroperovskites NaXF3 (X= Sr, Zn)

A theoretical study to investigate the electronic, optical and structural properties of sodium-based cubic fluoro-perovskite NaXF3 (where X = Sr, Zn), using density functional theory (DFT) based CASTEP (Cambridge Serial Total Energy Package) code with ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange-correlation functional of Generalized Gradient Approximation (GGA), is reported. The findings show that both compounds are in a stable form with a cubic structure. The calculated elastic constants also meet the mechanical stability criteria. NaSrF3 is brittle, while NaZnF3 is ductile, according to Pugh's criteria. The electronic band structure calculations reveal that NaSrF3 has a direct and NaZnF3 has an indirect band gap. The finding of band gap is agreed well with the data that is already available. The degree of localized electrons in different bands is confirmed by partial density of states (PDOS) and total density of states (TDOS). By fitting the dispersion relation for the hypothetical dielectric function scale to the corresponding peaks, the optical transitions in both compounds were investigated. Both materials are insulators at 0 K and semiconductor at high temperature. However, the dielectric function's imaginary component dispersion exposes its broad range of energy transparency. As a result, it can be inferred that these materials could be used to capture the ultraviolet region in optoelectronics.

Influence of (Li/Na/K) doping and point defect (VAl, Hi) on the magnetic and photocatalytic performance of AlN: A first-principles study

Although extensive reports on the influence of Li/Na/K doping on the physical properties of AlN systems exist, the effects of Li/Na/K doping and point defects (VAl, Hi) coexisting in AlN systems on magneto-optical properties are often neglected. Experimentally, Li/Na/K doping and point defects (VAl, Hi) cannot be precisely controlled. In this study, the generalized gradient approximation (GGA) plane wave ultrasoft pseudopotential + U method based on spin density functional theory is adopted to solve the abovementioned problem. The first-principles method is utilized to study the effects of point defects (VAl, Hi) and Li/Na/K doping on the photocatalytic performance of AlN systems. Compared with the Al34MN36 (M = Li/Na/K) system, the Al34MHiN36 (M = Li/Na/K) system presents reduced formation energy and improved stability. The Al34NaHiN36 system has the smallest formation energy and the highest stability. In particular, compared with all doped systems, the Al34NaHiN36 system has the best absorption spectrum redshift, the best carrier activity, the longest carrier lifetime, and the strongest oxidation capacity, that is, the best photocatalytic performance. The first-principles study indicates that N atoms in all Al34MN36 (M = Li/Na/K) and Al34MHiN36 (M = Li/Na/K) systems have acceptor and donor characteristics. The magnetic source of all doped systems is related to the double exchange of carriers as mediators, the itinerant electron polarization of unpaired N2− atoms and electric polarization. This study has certain theoretical guidance for the experimental design and preparation of new AlN magneto-optical functional materials.

Effect of different Mn doping and point vacancy ratios on the magnetic properties of ZnO

The magnetic source of Mn doping and Zn vacancy coexisting in ZnO is controversial. To solve this problem, this work used the generalized gradient approximation first-principles plane-wave ultrasoft pseudo potential + U method based on density functional theory to calculate the effect of different Mn doping to point vacancy ratios on the magnetic properties of ZnO. The formation energy of ZnO with different Mn-substituted Zn (MnZn) to oxygen/zinc vacancy (VO/VZn) ratios can be smaller and more stable in zinc (Zn)-rich conditions than in oxygen (O)-rich conditions. The ZnO system exhibits p-type half-metallic ferromagnetism when the MnZn to VZn ratio is 2:1 or 2:2. When the Mn doping amount is constant, the Zn vacancies increase and the total magnetic moment of the doped system decreases. For the ZnO system in which Mn doping and oxygen vacancies coexist, when the amount of oxygen vacancies is constant, with Mn doping increase, the magnetic moment becomes larger. Both Zn22Mn2O22 and Zn20Mn2O24 can achieve ferromagnetic characteristics above room temperature.

First-principles study of the effects of interstitial H and point vacancies on the photocatalytic performance of Be/Mg/Ca-doped GaN

The effects of Be/Mg/Ca doping on the optical properties of GaN have been widely investigated experimentally and theoretically. However, metalorganic chemical vapor deposition and vacuum coating methods are used in the experiments, and interstitial H is difficult to remove in GaN. The effects of Be/Mg/Ca doping and interstitial H coexistence with Ga vacancy on the photocatalytic performance of GaN are rarely explored in a vacuum environment. This study examines the formation energy and electronic structure of Ga34MN36 (M = Be/Mg/Ca) and Ga34MHiN36 (M = Be/Mg/Ca) systems and the main factors affecting their photocatalytic performance by using the generalized gradient approximation plane wave ultrasoft pseudopotential + U method within the framework of density functional theory. Results show that the formation energy of the Ga34MN36 (M = Be/Mg/Ca) and Ga34MHiN36 (M = Be/Mg/Ca) systems are greater under Ga-rich conditions than under N-rich conditions, indicating that both doping systems are more readily formed and have a more stable structure under N-rich conditions than under Ga-rich conditions. The visible light effect, electric dipole moment, effective mass, and oxidation–reduction reaction affecting the photocatalytic performance of the doping systems were analyzed. Compared with the Ga34MN36 (M = Be/Mg/Ca) system, the Ga34CaHiN36 system shows a more obvious red-shift in the absorption spectrum, a larger absorption spectrum intensity, a better carrier activity, a faster carrier separation rate, a longer carrier lifetime, and a stronger oxidation ability. These results suggest that the Ga34CaHiN36 system is an excellent photocatalyst that can be utilized in designing and preparing novel GaN photocatalysts.

First-principles study of acceptor Li/Ag/Cu doping and Zn vacancy on the magnetic mechanism of ZnO and the universality of itinerant electrons

Li/Ag/Cu doping and Zn vacancies have been theoretically and experimentally shown to induce ZnO to have room-temperature ferromagnetism. However, the source and mechanism of magnetic properties of such doped systems remain unclear. Previous researchers believe that all oxygen ions are negative divalent ions, as the basic assumption of the double-exchange interaction model, but no reasonable theoretical explanation has been put forward. Experimental control of Zn vacancies in ZnO is also challenging, but first principles can solve such problems. In this work, based on the generalized gradient approximation plane wave ultrasoft pseudopotential + U method under the framework of spin density functional theory, we used first principles to study the effect of the magnetic source and mechanism of Li/Ag/Cu doping and Zn vacancy on ZnO. We found that in addition to O2– ions, some O1– ions also existed in all doping systems. These ions had the dual-nature universality of itinerant electrons (donors) and local electrons (acceptors). The itinerant electrons in the Zn14LiO16, Zn14AgO16, and Zn14CuO16 systems further possessed the same spin. Compared with Zn14LiO16, Zn14AgO16, and Zn14CuO16 systems under the same doping amount, our results showed that the magnetic properties of Zn28Li2O32, Zn28Ag2O32, and Zn28Cu2O32 systems all increased. The Zn28Li2O32 system was found to be highly advantageous as a ferromagnetic functional material, which can guide the study of the magnetic source and mechanism of ZnO and similar oxide semiconductors through itinerant electrons.

Effects of different valence states of Mo and point vacancies on magneto-optical properties of ZnO

Experimental studies have been conducted to characterize the physical properties of Mo-doped ZnO. However, they have not considered the effects of different valence states and point vacancies on the magneto-optical performance of the system. The present study adopted the plane-wave ultrasoft pseudopotential + U method within the framework of spin density functional theory. The formation energy, electronic structure, and optical properties of ZnO systems with coexisting different valence states of Mo and point vacancies were calculated. Results showed that the formation energy of all doping systems was negative under Zn-rich and O-rich conditions, but the formation energy was relatively lower under O-rich conditions than under Zn-rich conditions. Compared with Mo6+ and Mo5+ when the concentration of O vacancies or Zn vacancies was the same, Mo6+-doped ZnO had the lowest formation energy, was the easiest to dope, and had the most stable system structure. Zn34Mo5+O36 and Zn34Mo6+O36 systems exhibited ferromagnetism, and their Curie temperature was above room temperature. The Zn34Mo6+O36 system had the largest magnetic moment, which is beneficial for designing and preparing new types of diluted magnetic semiconductors. The band gap widths of the Zn34Mo5+O36 (3.04 eV) and Zn34Mo6+O36 (2.92 eV) systems were both narrower than that of the pure ZnO system. By comparison, the band gap widths of the Zn35Mo5+O35 and Zn35Mo6+O35 systems were 4.07 and 3.94 eV, respectively. Although the band gap width widened, under light excitation conditions, the valence band electrons could absorb the photons of lower energy to transition to the impurity energy level, and then transition further from the impurity energy level to the conduction band. During the hierarchical transition, visible light and infrared light effects still occurred. The range of photon energy response of all doping systems expanded, and the absorption spectrum red-shifted in the light-absorption edge within the low-energy (0–3.2 eV) range. In particular, the Zn35Mo6+O35 system exhibited the strongest polarization ability, photoelectric field strength, and charge-binding ability in the low-energy region. Moreover, the dielectric and absorption peaks of the imaginary part of the dielectric function were relatively large, and the red-shift of the absorption spectrum was relatively substantial. Therefore, the Zn35Mo6+O35 system is useful in designing and preparing novel ZnO-based photocatalysts.

Triaxial strain effect on the electron transport performance and absorption spectrum of ZnO

The effect of triaxial strain on the electron transport performance and absorption spectrum of ZnO has been rarely reported. In this paper, the generalized gradient approximation plane wave ultrasoft pseudopotential + U method based on the spin density functional theory is adopted to solve this problem. The first-principle method is utilized to study the triaxial strain on the electron transport performance and absorption spectrum of ZnO. Results show that the binding energy of Zn36O36 is 2.14 eV when the system is unstrained and relatively stable. The formation energy of the Zn36O36 system increases with the increase in tensile or compressive strain, and the system stability decreases. The formation energy of the O-vacancy system is smaller compared with the same orders of magnitude of tensile or compressive strain. The formation energy of O-vacancy system is smaller, and the structure is stable when the system is tensile strain. Specifically, the absorption spectrum of the Zn36O35 system has the optimal redshift and intensity when the tensile strain is 5%. The electron mobility of the Zn36O36 system along the y direction (G → F) is relatively large when the compressive strain is −5%, the band gap of the system is wide, and the blueshift of the absorption spectral distribution is obvious. This work has a certain theoretical guidance for the design and preparation of novel ultraviolet light detectors or improvement of the electron transmission performance.

Study the effect of magnesium doping concentration on structural and optoelectronic response of NaCa1-xMgxF3 fluoro-perovskite: First-principles computation

Methodology of all-electron self-consistent ultra-soft pseudopotential plane wave in PBE Generalized Gradient density approximations have been applied to investigate structural, electronic and optical properties of cubic pure and magnesium doped NaCaF3 fluoro-perovskite. Our evaluated optimized structural parameters for pure NaCaF3 are well in agreement with the already reported results and optimized structural parameters for magnesium doped (1.41 %, 2.82 % and 4.23 %) NaCaF3 are reported first time. The electronic band structure calculation for pure and magnesium doped NaCaF3 has revealed a direct band transition with the bandgap values of 4.773 eV–3.325 eV, respectively. The degree of localized electrons in different bands is confirmed by total and partial densities of states. The transitions in optical properties of pure and magnesium doped NaCaF3 material were recognized by assigning corresponding peaks obtained and are discussed in line of structural-electronic determinations. This is the first theoretical study of cubic crystal structure of magnesium doped NaCaF3 as far as we know.

Effects of point vacancy and interstitial H on the carrier activity, separation, and absorption spectrum of ZnO: Li/Na/K

The accurate understanding of Li/Na/K doping and point vacancies in ZnO is difficult. The interstitial H is also neglected in ZnO. In this paper, the generalized gradient approximation plane wave ultrasoft pseudopotential + U method is adopted based on the spin density functional theory to solve the abovementioned problem. The First-principles method is utilized to study the point vacancies and interstitial H on ZnO: Li/Na/K carrier activity, separation, and absorption spectrum. The formation energy of the Zn35MHiO35 (M: Li/Na/K) system is a large positive value regardless of the O- and Zn-rich conditions, indicating the difficulty of Zn35MHiO35 (M: Li/Na/K) system's formation and its poor stability. Compared with the same doping system, the Zn34MHiO36 (M: Li/Na/K) system exhibits smaller formation energy under O-rich conditions and is more stable. The formation energies of different doping systems under O- or Zn-rich conditions are in the following order: Zn35NaHiO35＜Zn35KHiO35＜Zn35LiHiO35. Zn35NaHiO35 and Zn35KHiO35 have negative formation energy and good stability. According to the analysis of the electric dipole moment, effective mass, and absorption spectrum, Zn35NaHiO35 can be separated easily and has the strongest carrier activity, the best absorption spectrum intensity, and the best red shift. These features are relatively advantageous in designing and preparing novel ZnO photocatalysts.

High-performance strontium and bismuth bimetallic oxides electrode：combine first-principles calculations with electrochemical tests

A series of bimetallic oxides electrode materials were proposed to boost the supercapacitor performance using the density functional theory (DFT) in combination with the electrochemical tests. This work provides a guiding role for exploring energy storage materials with high performance. Based on the plane wave ultra-soft pseudo-potential (PWPP) and general gradient approximate (GGA) in DFT, the electronic and the crystal structures of various strontium bismuth oxides (β-Bi2O3, SrBi2O4, Sr2Bi2O5 and SrBiO3) were calculated, and the corresponding energy bands were compared. The simulation results show that SrBiO3 has a smaller band gap than the other three oxides, due to the significant hybridization of the electronic density of SrBiO3. The prepared strontium bismuth oxide materials (SrBi2O4, Sr2Bi2O5 and SrBiO3) were characterized using scanning electron microscopy (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD), respectively. In the electrochemical measurement of 6M KOH solution, SrBiO3 presents the highest specific capacity of 810.93F g−1 (i.e. 126.95 mAh g−1) at a current density of 1A g−1. The capacitance retention rate of SrBiO3 is 80.11 % after 2000 cycles, which indicates that it has the useful properties of cyclic stability. All the results suggest that SrBiO3 will be an excellent candidate in electrode materials for the battery-type supercapacitors.

Theoretical study on Schottky regulation of WSe<sub>2</sub>/graphene heterostructure doped with nonmetallic elements

采用平面波超软赝势方法研究了非金属元素掺杂对二硒化钨/石墨烯肖特基电子特性的影响. 研究表明二硒化钨与石墨烯层间以范德瓦耳斯力结合形成稳定的结构. 能带结果表明二硒化钨与石墨烯在稳定层间距下形成n型肖特基势垒. 三维电子密度差分图表明石墨烯中的电子向二硒化钨移动, 使二硒化钨表面带负电, 石墨烯表面带正电, 界面形成内建电场. 分析表明, 将非金属原子掺杂二硒化钨可以有效地调控二硒化钨/石墨烯肖特基势垒的类型和高度. C, O原子掺杂二硒化钨时, 肖特基类型由p型转化为n型, 并有效降低了肖特基势垒的高度; N, B原子掺杂二硒化钨时, 掺杂二硒化钨体系表现出金属性, 与石墨烯接触表现为欧姆接触. 本文结果可为二维场效应晶体管的设计与制作提供相关指导.

First-principles study on electronic structure and photoelectric properties of zinc blende InxGa1-xN with different in doping concentrations

The first-principles ultra-soft pseudopotential plane wave based on density functional theory is used to calculate the electronic structure and photoelectric properties of zinc blende GaN and zinc blende InxGa1-xN with different In doping concentrations (x=0, 0.125, 0.25, 0.375, 0.5). It is shown that zinc blende GaN and its In-doped system are all direct bandgap semiconductor materials. With the increase of In doping concentration, the lattice constant of InxGa1-xN increases and the band gap decreases, the absorption spectrum shift to the red region. Therefore, it can be inferred that by adjusting the doping concentration of In, the light absorption range of InxGa1-xN can cover the entire solar spectrum, which means that InxGa1-xN can be worthy to fabricate photovoltaic devices such as full-spectrum solar cells.