Identification of a functional point defect in SrTiO3

Survey of acceptor dopants in SrTiO3: Factors limiting room temperature hole concentration

“…38 Anti-site (Ti Sr and Sr Ti ) and interstitial defects (Sr i-tet , Sr i-oct , Ti i-tet , and Ti i-oct ) were found to be unfavorable in all conditions. Ti Sr,dx is more energetically favorable than the on-site configuration, but its formation energy is still too high to form in appreciable concentrations at equilibrium which is consistent with the results of Lee et al 65 Figure 2E and At 25°C, there is a sudden decrease in μ e with increasing oxygen activity. This transition does not correspond to a change in the dominant charge compensation mechanism.…”

“…Anti‐site (Ti Sr and Sr Ti ) and interstitial defects (Sr i‐tet , Sr i‐oct , Ti i‐tet , and Ti i‐oct ) were found to be unfavorable in all conditions. Ti Sr,dx is more energetically favorable than the on‐site configuration, but its formation energy is still too high to form in appreciable concentrations at equilibrium which is consistent with the results of Lee et al…”

In situ anion-doped epitaxial strontium titanate films

“…For oxygen vacancy V O in STO, the neighboring Ti ions are displaced away from the vacancy and the lattice locally stretches along the Ti-V O -Ti direction. [13][14][15][16][17] This local lattice anisotropy averages out on the macroscopic level for a conventional random spatial distribution of the vacancies; the corresponding chemical lattice expansion is usually isotropic. However, in the epitaxial STO/ LSAT films, the in-plane compression can promote the vacancy formation in the Sr-O planes parallel to the substrate (001) surface, i.e.…”

“…The oxygen vacancies and anion dopants at oxygen sites produce diverse in-gap states in STO. [13][14][15][16][17][18][19][20][21][22][23][24] Because the optical transitions from/to these states are fingerprints of the vacancies and dopants, investigations of the optical absorption coefficient a can disentangle the vacancy formation and anion interstitial or substitutional incorporation.…”

Defect accommodation in off-stoichiometric (SrTiO3)nSrO Ruddlesden–Popper superlattices studied with positron annihilation spectroscopy

“…For titanium-rich films it is known that there is a corresponding increase in strontium vacancies, titanium antisite defects, and amorphous TiO 2 -rich regions. [7][8][9][10] For strontium-rich SrTiO 3 , the defect mechanisms are less well understood. In bulk SrTiO 3 , (SrO) 2 faults are observed with strontium excess of >0.01 at.%, 11,12 forming disordered (SrTiO 3 ) n SrO Ruddlesden-Popper phases.…”