Comparative Study for effect of Ti, Nb and W incorporation on the Electronic and Optical Properties of Pristine Hafnia (m-HfO 2 ): DFT Theoretical prospective

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Abstract First-principles calculations using the Hubbard approach (DFT + U) with PBEsol correlation were carried out to do comparative study of the effects of the incorporation of 3d, 4d, and 5d metal atoms on the electronic and optical properties of m-HfO2. The incorporation of metal atoms in the crystal structure of HfO2 displaced the band gap edges and downshift conduction band minimum (CBM) which led to band gap tightening as the following 5.24, 3.26, 1.12, and 0.92 eV for HfO2, HfO2:Ti, HfO2:W, HfO2:Nb respectively. The total density of states (DOS) and partial density of states (PDOS) calculations illustrated that the VBM of pristine HfO2 is mainly constructed by O 2p states, while the CBM is constructed mainly by Hf 4d sates. For doped crystals the conduction band minimum (CBM) are mainly constructed by 3d, 4d and 5d sates of Ti, Nb, and W respectively. For pristine HfO2, the results obtained for the real and imaginary parts of dielectric function, reflectivity, and the refractive index show good matching with the available experimental and theoretical findings. For doped systems, there are clear similarity in the effect of the incorporation of Nb (4d metal ) and W(5d metal) on the electronic and optical properties of HfO2, which differed to large extent than the effect of the incorporation of Ti (3d metal). The absorption of HfO2 is duplicated upon Ti atom insertion (HfO2:Ti). The difference between 3d, 4dm and 5d metal doping still need further study to understand it and to know what is better as dopant in tuning electronic and optical properties of this promising metal oxide HfO2 and other metal oxides.

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