JART OxRelax

In the search for an oxide-based 2D electron system with a large concentration of highly mobile electrons, a promising strategy is to introduce electrons through donor doping while spatially separating electrons and donors to prevent scattering. In SrTiO3, this can be achieved by tailoring the oxygen vacancy profile through reduction, e.g., by creating an interface with an oxygen scavenging layer. Through reduction, oxygen atoms are removed close to the interface, leaving behind oxygen vacancies in the SrTiO3 lattice and mobile electrons in the SrTiO3 conduction band. The commonly assumed picture is that the oxygen vacancies then remain confined close to the interface while the electrons leak a few nanometers into the bulk, resulting in an electron-defect separation and a highly mobile, oxide-based 2D electron system. Here, we present a transient finite element simulation tool that describes how the concentration profiles of oxygen vacancies and electrons develop over a timescale from minutes to 10 years at temperature T. This tool considers three driving forces acting on the oxygen vacancy distribution: diffusion due to the concentration gradient, drift due to the intrinsic electric field, and an oxygen vacancy trapping energy that holds oxygen vacancies at the interface. Furthermore, this tool provides data that can be compared to conductivity measurements at a second temperature T_LT. This COMSOL App is available without (small – 15 MB) and with (large – 744 MB) COMSOL runtime. In the first case, the download is significantly smaller and the COMSOL runtime will be automatically installed if necessary.