Self-diffusion of constituent elements in nominally undoped LaAlO3 single crystals

The interface between the insulators LaAlO3 and SrTiO3 has very interesting electronic properties. The production of such heterointerfaces comprises high temperature steps. Therefore knowledge of the mobilities of the constituent elements in the two partner oxides is required. As the majority of the published oxygen mobility data is based on electrical conductivity measurements with a rather large scatter, a check with a direct method was required, i. e. 18O2 exchange in combination with SIMS depth profiling. Our present results are in agreement with recently published 18O2/SIMS data. For the two native cations no data at all were available in the literature. Using the rare stable isotope 138La and the pseudo-stable radionuclide 26Al in combination with SIMS depth profiling, for the first time upper limits of the tracer diffusivities could be determined at one temperature (1500 °C) for the very slow host cations in nominally undoped (100) oriented LaAlO3 single crystals. The experimental observations of this work for LaAlO3 are very similar to the situation in SrTiO3 concerning the cation tracer diffusivities in nominally undoped single crystals. Both the experimental findings in LaAlO3 and in SrTiO3 are in plausible qualitative agreement with the results of calculated activation energies for native ion migration in various perovskite oxides. •Investigation of tracer diffusivities in nominally undoped LaAlO3 single crystals.•Tracer isotopes 18O, 26Al and 138La in combination with SIMS.•First investigation of cation diffusivity in LaAlO3.•The mobility of the cations in nominally undoped LaAlO3 is very low.