GaN, global optimization, screw dislocations, theory Band gap reduction and dielectric function of Ga_(1-x)Zn_xN_(1-x)O_x and In_(1-x)Zn_xN_(1-x)O_x alloys

摘要

The band gap reductions, dielectric functions and absorption coefficients of the Ga_(1-x)Zn_xN_(1-x)O_xand In_(1-x)Zn_xN_(1-x)O_x (x=0.00, 0.25, 0.50, 0.75, and 1.00) alloys were calculated, employing the partial self-consistent GW approximation. As a comparison, the local density approximation (LDA) and the Heyd-Scueria-Ernzerhof (HSE) hybrid functional were also used to calculate the gap reduction. Both Ga_(1-x)Zn_xN_(1-x)O_x and In1-xZnxN1_xOx alloys show strong band gap bowing. As a result, the band gap energy in Ga_(1-x)Zn_xN_(1-x)O_x is reduced by Eg(GaN)-Eg(Ga_(1_x)Zn_xN_(1-x)O_x)= 1.61,2.01 and 1.91eVfor x = 0.25, 0.50, and 0.75, respectively. This allows optoelectronic devices based on GaN and ZnO with more efficient absorption or emission of light in the visible light range. The calculated dielectric functions and absorption spectra demonstrate that the band gap reduction enhances the optical absorption around the 2.5 eV region. Interestingly, the In_(1-x)Zn_xN_(1-x)O_x alloy with x = 0.25 has the large optical absorption coefficient in the energy region 0.69-6.0 eV, and the alloy has very good absorption at 2-3 eV.