A DFT study of Alkaline-earth-metal-doped Hf1 − xAxO2(A = Be, Mg, Ca) for photovolataic applications

Abstract

In this work, Density Functional Theory (DFT) has been employed to examine the structural, electronic, magnetic and optical characteristics of alkaline earth metals doped (Be, Mg and Ca) doped (Hf_1-xA_xO₂) alloys using the FP-LAPW (full-potential augmented plane wave plus local orbital) method and GGA and TB-mBJ exchange correlation methods. All studied compounds are structurally stable due to negative (formation energy) values. The computed results, including the band gap and lattice characteristics, correspond well with the existing experimental results. According to the band structure and density of states calculation, Hf_1-xA_xO₂ has wider band gaps for spin up configuration and reduced energy gaps of 4.71 3.41, 3.35 and 3.02 eV has been found for pure c-HfO₂, Hf_1-xMg_xO_2, Hf_1-xCa_xO₂ and Hf_1-xBe_xO₂ respectively. The PDOS results demonstrate that the formation of conduction and valance bands is due to Hf-6s orbitals and Mg/Ca/Be-s states. Additionally, we have investigated the optical characteristics that correspond to the real and imaginary portion of the dielectric function in the region of 0–12 eV, such as absorption coefficient, optical conductivity, refractive index, reflectivity and energy loss function. Moreover, Hf_1-xCa_xO₂ has a wide range of absorption in the UV-visible region, which indicates that this material is suitable for opto-electronic and solar cell applications. The refractive index suggests that Hf_1-xCa_xO₂ could be a potential candidate for applications to high-density optical data storage devices.