Fig. 1: SrTiO3 unit cell. Ti-violet, Sr-green, O-blue.
Fig. 2: SrTiO3 (001)
Fig. 3: SrTiO3 (110)
Fig. 4: SrTiO3 (111)
The lattice is cubic with a lattice constant of a=3.905Å.
The size of commercial SrTiO3 substrates is usually either 10 × 10 mm2 or 15 × 15 mm2. We mostly use substrates that have been etched in NH4F-HF to remove Sr residue and to get a high-quality step-and-terrace structure on the surface.
Some of the more interesting crystallographic directions of the STO surface are shown below. Color coding is the same as in the Fig. 1 unit cell.
The Ti layer is the terminating layer in these images. Obviously other terminating layers (like Sr) are also possible. The different crystal cut directions are useful because the (100) surface is cubic, the (110) surface is tetragonal, and the (111) surface has 6-fold symmetry.