On the basis of first principles calculations using density functional theory, we explore the structural and electronic properties of two binaries: CaO and MgO in rock salt structures. Structural properties of the sem...On the basis of first principles calculations using density functional theory, we explore the structural and electronic properties of two binaries: CaO and MgO in rock salt structures. Structural properties of the semiconductor CaχMg1-χO alloys are derived from total-energy minimization within the General Gradient Approximation. The band gap bowing parameters dependence is very powerful Calcium composition. The results offer that an average bowing parameter of CaχMg1-χO alloys is b = ~0.583$ eV. We analyzed the volume deformation, charge transfer and structural relaxation effects of the CaχMg1-χO alloys.展开更多
讨论了计算In Ga As Sb四元合金材料禁带宽度常用的Glisson方法和Moon方法,比较了它们的计算结果.将两者化成相同形式下的等价公式后发现,二者都只考虑了Γ点带隙弯曲因子对禁带宽度的影响.通过考虑自旋轨道分裂带对价带的影响,提出一...讨论了计算In Ga As Sb四元合金材料禁带宽度常用的Glisson方法和Moon方法,比较了它们的计算结果.将两者化成相同形式下的等价公式后发现,二者都只考虑了Γ点带隙弯曲因子对禁带宽度的影响.通过考虑自旋轨道分裂带对价带的影响,提出一种将自旋轨道分裂带弯曲因子引入计算In Ga As Sb禁带宽度的新方法.研究结果表明,该方法计算结果的准确性要优于两种常见的方法.展开更多
First-principles investigation of BAs and BxGa1-xAs alloys Using first-principles calculations in the generalized gradient approximation, the electronic properties of BAs and BxGa1-xAs alloys are studied. At the Bri...First-principles investigation of BAs and BxGa1-xAs alloys Using first-principles calculations in the generalized gradient approximation, the electronic properties of BAs and BxGa1-xAs alloys are studied. At the Brillouin-zone centre, the lowest conduction band is the three-degenerate p-like Г15c state rather than s-like Г1c state, and the conduction band minimum （CBM） is along the A line between the Г and X points-at approximately 11/14（1,0,0）2π/a. With boron content at 0%-18.75%, BxGa1-xAs alloys have a small （2.6 eV） and relatively composition-independent band-gap bowing parameter, the band-gap increases monotonically by -18meV/B% with increasing boron content. In addition, the formation enthalpies of mixing for BxGa1-xAs alloys with boron content at 6.25% and 12.5% are calculated, and the large formation enthalpies may explain the difficulty in alloying boron to GaAs.展开更多
The band structures of BSb and BxGa1-xSb alloys are studied using first-principles calculations in the generalized gradient approximation. By SQS-8 supercells to model a random alloy, the direct transition energy-gap ...The band structures of BSb and BxGa1-xSb alloys are studied using first-principles calculations in the generalized gradient approximation. By SQS-8 supercells to model a random alloy, the direct transition energy-gap (Γ15v- Γ1c) bowing of 3.0 eV is obtained for BxGa1-xSb alloys in x = 0-50%, in x = 0-11% the energy-gap is the band-gap and increases by 7 meV/%B with boron composition increasing; by SQS-16 supercells the bowing parameter is about 1.9 eV in x = 0-12.5%. The formation enthalpies of mixing, ΔH, are calculated for BxGa1-xAs and BxGa1-xSb alloys. A comparison of enthalpies indicates that BxGa1-xSb films with boron composition of 7% may be possible.展开更多
文摘On the basis of first principles calculations using density functional theory, we explore the structural and electronic properties of two binaries: CaO and MgO in rock salt structures. Structural properties of the semiconductor CaχMg1-χO alloys are derived from total-energy minimization within the General Gradient Approximation. The band gap bowing parameters dependence is very powerful Calcium composition. The results offer that an average bowing parameter of CaχMg1-χO alloys is b = ~0.583$ eV. We analyzed the volume deformation, charge transfer and structural relaxation effects of the CaχMg1-χO alloys.
文摘讨论了计算In Ga As Sb四元合金材料禁带宽度常用的Glisson方法和Moon方法,比较了它们的计算结果.将两者化成相同形式下的等价公式后发现,二者都只考虑了Γ点带隙弯曲因子对禁带宽度的影响.通过考虑自旋轨道分裂带对价带的影响,提出一种将自旋轨道分裂带弯曲因子引入计算In Ga As Sb禁带宽度的新方法.研究结果表明,该方法计算结果的准确性要优于两种常见的方法.
基金Project supported by the National Basic Research Program of China (Grant No 2003CB314901)the Program for New Century Excellent Talents in University (Grant No NCET-05-0111)the National Natural Science Foundation of China (Grant No 60576018)
文摘First-principles investigation of BAs and BxGa1-xAs alloys Using first-principles calculations in the generalized gradient approximation, the electronic properties of BAs and BxGa1-xAs alloys are studied. At the Brillouin-zone centre, the lowest conduction band is the three-degenerate p-like Г15c state rather than s-like Г1c state, and the conduction band minimum （CBM） is along the A line between the Г and X points-at approximately 11/14（1,0,0）2π/a. With boron content at 0%-18.75%, BxGa1-xAs alloys have a small （2.6 eV） and relatively composition-independent band-gap bowing parameter, the band-gap increases monotonically by -18meV/B% with increasing boron content. In addition, the formation enthalpies of mixing for BxGa1-xAs alloys with boron content at 6.25% and 12.5% are calculated, and the large formation enthalpies may explain the difficulty in alloying boron to GaAs.
基金Supported by the National Natural Science Foundation of China (Grant No.10774031)the Guangdong Provincial Natural Science Foundation (Grant No.07001790)
文摘The band structures of BSb and BxGa1-xSb alloys are studied using first-principles calculations in the generalized gradient approximation. By SQS-8 supercells to model a random alloy, the direct transition energy-gap (Γ15v- Γ1c) bowing of 3.0 eV is obtained for BxGa1-xSb alloys in x = 0-50%, in x = 0-11% the energy-gap is the band-gap and increases by 7 meV/%B with boron composition increasing; by SQS-16 supercells the bowing parameter is about 1.9 eV in x = 0-12.5%. The formation enthalpies of mixing, ΔH, are calculated for BxGa1-xAs and BxGa1-xSb alloys. A comparison of enthalpies indicates that BxGa1-xSb films with boron composition of 7% may be possible.
