Effect of buffer termination on intermixing and conductivity in LaTiO3/SrTiO3 heterostructures integrated on Si(100)

The control of chemical exchange across heterointerfaces formed between ultrathin functional transition-metal oxide layers provides an effective route to manipulate the electronic properties of these systems. By determining the layer-resolved structural profile across the interface between the Mott insulator, LaTiO3 (LTO) grown epitaxially on SrTiO3 (STO)-buffered silicon by molecular beam epitaxy, we find that interfacial cationic exchange depends on the surface termination of the strained STO buffer. Using a combination of temperature-dependent transport and synchrotron x-ray crystal truncation rods and reciprocal space mapping, an enhanced conductivity in STO/LTO/SrO-terminated STO buffers compared to heterostructures with TiO 2-terminated STO buffers is correlated with La/Sr exchange and the formation of metallic La 1−xSr xTiO 3. La/Sr exchange effectively reduces the strain energy of the system due to the large lattice mismatch between the nominal oxide layers and the Si substrate.