The electronic band structures and band gap bowing parameters of In_xGa_（1-x）N are studied by the firstprinciples method based on the density functional theory. Calculations by employing both the Heyd-ScuseriaErnzer...The electronic band structures and band gap bowing parameters of In_xGa_（1-x）N are studied by the firstprinciples method based on the density functional theory. Calculations by employing both the Heyd-ScuseriaErnzerh of hybrid functional（HSE06） and the Perdew-Burke-Ernzerhof（PBE） one are performed. We found that the theoretical band gap bowing parameter is dependent significantly on the calculation method, especially on the exchange-correlation functional employed in the DFT calculations. The band gap of In_xGa_（1-x）N alloy decreases considerably when the In constituent x increases. It is the interactions of s–s and p–p orbitals between anions and cations that play significant roles in formatting the band gaps bowing. In general, the HSE06 hybrid functional could provide a good alternative to the PBE functional in calculating the band gap bowing parameters.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(Γ...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
基金Project supported by the National Natural Science Foundation of China(Nos.11204257,21233004)the China Postdoctoral Science Foundation(No.2012M511447)
文摘The electronic band structures and band gap bowing parameters of In_xGa_（1-x）N are studied by the firstprinciples method based on the density functional theory. Calculations by employing both the Heyd-ScuseriaErnzerh of hybrid functional（HSE06） and the Perdew-Burke-Ernzerhof（PBE） one are performed. We found that the theoretical band gap bowing parameter is dependent significantly on the calculation method, especially on the exchange-correlation functional employed in the DFT calculations. The band gap of In_xGa_（1-x）N alloy decreases considerably when the In constituent x increases. It is the interactions of s–s and p–p orbitals between anions and cations that play significant roles in formatting the band gaps bowing. In general, the HSE06 hybrid functional could provide a good alternative to the PBE functional in calculating the band gap bowing parameters.
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.
