Defect chemistry and resistance degradation in Fe-doped SrTiO3 single crystal

Abstract

Defect chemistry and transport in Fe-doped SrTiO 3 single crystal are studied to understand its resistance degradation mechanism. The temporal evolution of electric conductivity under a voltage stress was obtained computationally by solving the transport equations for ionic and electronic defects coupled with the defect reaction equilibrium equations. The computational results are compared to the corresponding experimental measurement under similar conditions. It is shown that the local electron and hole concentrations are controlled by the local electronic defect equilibria rather than by their quasi-steady state diffusional transport. It is the electric field-induced migration of oxygen vacancies and the subsequent instantaneous reestablishment of the local defect equilibria that lead to the resistance degradation. The resistance degradation behavior and the defect distributions under a long-term voltage stress are strongly influenced by the sample-annealing oxygen partial pressure, degrading electric field, and temperature. The present study contributes to the understanding of resistance degradation mechanism and provides guidance to improve the lifetime and reliability of wide band-gap semiconducting capacitors.

Defect mechanisms of coloration in Fe-doped SrTiO3 from first principles

“…3,12,[18][19][20][21] These models then adjust the ionization of the Fe dopant until predictions fit a measured physical property. Nevertheless, a number of EPR studies have detected the presence of a first nearest neighbor iron oxygen vacancy complex, which suggests this interaction is non-negligible.…”

Phase‐Field Model of Electrothermal Breakdown in Flexible High‐Temperature Nanocomposites under Extreme Conditions

“…Computationally predicted and experimentally measured breakdown strength as function of temperature for PI-STO nanocomposites with a) 5 vol% randomly distributed STO nanoparticles in ref. electrical conductivity of 2.0 × 10 −5 Sm −1 , [43] the effective electrical conductivity for microstructures defined in the dataset ranges from 4.3 × 10 −13 to 9.8 × 10 −11 Sm −1 . [34], and c) 10 vol% in-plane parallel STO nanosheets, and for d) the c-BCB/h-BNNS nanocomposite with 10 vol% parallel h-BN nanosheets, compared with the available experimental data in ref.…”

A comparison study of solving diffusion equations with different algorithm methods

“…[9][10][11][12][13] The point defect play a significant role in the breakdown and degradation of materials, therefore the defect evolution becomes a major concern in the applications of dielectric and ferroelectric materials. [14][15][16] The defect transports of breakdown and degradation processes have been widely investigated experimentally. The resistance degradation rates of dopant, temperature, and voltage dependences in SrTiO 3 ceramics and single crystals were investigated by Waser et al 17,18 The oxygen vacancy concentration is critical in the resistance degradation, and it increased across the dielectric layers towards the cathode while decreased toward the anode region.…”

“…The resistance degradation was resulted from the electric field-induced migration of oxygen vacancies and the subsequent instantaneous reestablishment of the local defect equilibria. 16 In fact, PFM can be solved by using finite element, finite difference, or semi-implicit spectral methods, but FSM has been used in solving several order parameters coupling problems. For example, Cao et al 29,30 proposed a numerical model combining PFM for ferroelectric domain structures and diffusion equations for defect transport to study the resistance degradation behavior in single and multi-domain tetragonal BaTiO 3 capacitors.…”