Investigation of structural and electronic properties of doped ceria Ce1-xMxO2 (M=Hf,Ti,Ba,Mg,Nb,Vx=0.25%) for ReRAM applications: A first principles study

Since last few decades, in-spite of much progress in oxide-based resistive random access memory (ReRAM) devices, there are many challenges to the era of science and technology, particularly information and rupture of the conducting filament and device uniformity related concerns. The first principles calculations based on density functional theory (DFT) were made to investigate structural and electronic properties of doped ceria (CeO2), i.e., Ce1-xMxO2 (M = Hf, Ti, Ba, Mg, V, Nb x = 0.25%) with and without oxygen vacancy (Vo) for ReRAM devices wherein six dopants having different electronic configuration and radii are used. Effect of isovalent, low-valent (p-type) and high-valent (n-type) dopants was observed using the Perdew, Burke and Ernzerhof and generalized gradient approximation (PBE-GGA) approach. The present study also elaborates the role of oxygen vacancy in formation and rupture of conducting filaments (Cfs). The tendency towards reduction of oxygen vacancy formation energies to improve device performance has been observed for all dopants and found consistent with available data. We explored that the dopants impact oxygen vacancy formation energies locally and increase the clustering of Vo near dopants as a results conductivity has been increased. Structural investigation unveiled that in all cases, volume of the crystal lattice increases with dispense of the band gap energies which lead to enhance conductivity. TDOS and PDOS results show that energy states are shifted towards lower energy region due to dopant and/or oxygen vacancy. The oxygen vacancy in the lattice causes the formation of defect assisted conducting channels in the resistive switching devices.