Two-dimensional electron gas generated by La-doping at SrTiO3(001) surface: A first-principles study

We carried out first-principles calculations to study the electronic properties of SrO-terminated and TiO2-terminated SrTiO3(001) surfaces with La-doping at the surface. We find that an intrinsic lower-lying state at the SrO-terminated surface can accommodate a two-dimensional electron gas (2DEG). By introducing La-doping at the SrO-terminated surface the energy position of the surface state and the 2DEG density can be tuned by changing the doping concentration. The higher the La-doping concentration, the lower the lower-lying state and the higher the 2DEG density. This 2DEG has a small effective mass and hopefully shows a high mobility.