Density functional theory analysis of electronic structure and optical properties of La-doped Cd₂SnO₄ transparent conducting oxide

【摘要】 The electronic structural, effective masses of carriers, and optical properties of pure and La-doped Cd₂SnO₄ are calculated by using the first-principles method based on the density functional theory. Using the GGA+U method, we show that Cd₂SnO₄ is a direct band-gap semiconductor with a band gap of 2.216 eV, the band gap decreases to 2.02 e V and the Fermi energy level moves to the conduction band after La doping. The density of states of Cd₂SnO₄ shows that the bottom of the conduction band is composed of Cd 5 s, Sn 5 s, and Sn 5 p orbits, the top of the valence band is composed of Cd 4d and O 2p, and the La 5 d orbital is hybridized with the O 2 p orbital, which plays a key role at the conduction band bottom after La doping. The effective masses at the conduction band bottom of pure and La-doped Cd₂SnO₄ are 0.18 m0 and 0.092 m₀, respectively, which indicates that the electrical conductivity of Cd₂SnO₄ after La doping is improved. The calculated optical properties show that the optical transmittance of La-doped Cd₂SnO₄ is 92%, the optical absorption edge is slightly blue shifted, and the optical band gap is increased to 3.263 eV. All the results indicate that the conductivity and optical transmittance of Cd₂SnO₄ can be improved by doping La.更多还原

【Abstract】 The electronic structural, effective masses of carriers, and optical properties of pure and La-doped Cd₂SnO₄ are calculated by using the first-principles method based on the density functional theory. Using the GGA+U method, we show that Cd₂SnO₄ is a direct band-gap semiconductor with a band gap of 2.216 eV, the band gap decreases to 2.02 e V and the Fermi energy level moves to the conduction band after La doping. The density of states of Cd₂SnO₄ shows that the bottom of the conduction band is composed of Cd 5 s, Sn 5 s, and Sn 5 p orbits, the top of the valence band is composed of Cd 4d and O 2p, and the La 5 d orbital is hybridized with the O 2p orbital, which plays a key role at the conduction band bottom after La doping. The effective masses at the conduction band bottom of pure and La-doped Cd₂SnO₄ are 0.18 m₀ and 0.092 m₀, respectively, which indicates that the electrical conductivity of Cd₂SnO₄ after La doping is improved. The calculated optical properties show that the optical transmittance of La-doped Cd₂SnO₄ is 92%, the optical absorption edge is slightly blue shifted, and the optical band gap is increased to 3.263 eV. All the results indicate that the conductivity and optical transmittance of Cd₂SnO₄ can be improved by doping La.更多还原