Parameterization of CuIn1-xGaxSe2 (x = 0, 0.5, and 1) energy bands

Parameterization of the electronic band structure of CuIn1-xGaxSe2 (x = 0, 0.5, and 1) demonstrates that the energy dispersions of the three uppermost valence bands [Ej(k); j = v1, v2, and v3] are strongly anisotropic and non-parabolic even very close to the Γ-point valence-band maximum Ev1(0). Also the lowest conduction band Ec1(k) is anisotropic and non-parabolic for energies ∼ 0.05 eV above the band-gap energy. Since the electrical conductivity depends directly on the energy dispersion, future electron and hole transport simulations of CuIn1-xGaxSe2 need to go beyond the parabolic approximation of the bands. We therefore present a parameterization of the energy bands, the k-dependency of the effective electron and hole masses mj(k), and also an average energy-dependent approximation of the masses mj(E).