Hysteretic electrical transport in BaTiO3/Ba1−xSrxTiO3/Ge heterostructures

We present electrical transport measurements of heterostructures comprised of BaTiO3 and Ba1−xSrxTiO3 epitaxially grown on Ge. Sr alloying imparts compressive strain to the BaTiO3, which enables the thermal expansion mismatch between BaTiO3 and Ge to be overcome to achieve c-axis oriented growth. The conduction bands of BaTiO3 and Ba1−xSrxTiO3 are nearly aligned with the conduction band of Ge, which facilitates electron transport. Electrical transport measurements through the dielectric stack exhibit rectifying behavior and hysteresis, where the latter is consistent with ferroelectric switching.