Carrier Behavior in SrTiO₃ Films Grown on p- and n- Silicon by Molecular Beam Epitaxy

Strontium titanate (SrTiO₃ or STO) is a perovskite oxide that is widely used in optoelectronics. STO is a semiconductor with a bandgap of ~3.2 eV and is typically n-type due to Oxygen vacancies but the charge carrier density depends strongly on the growth conditions. In this work, we characterize STO thin films grown by molecular beam epitaxy (MBE) on both n and p-type Si (001) substrates under controlled oxygen background pressures. Because growth occurs in an oxygen deficient environment, the resulting STO f ilms exhibit n-type conductivity due to oxygen vacancies. We investigate the electronic properties of these STO films between 200 and 300 K using Van der Pauw and Hall measurements to extract sheet resistance, carrier concentration, and mobility. The STO f ilm grown on n-type Si shows lower resistance near 300 K compared to the film on p-type Si, a difference attributed to the substrate contribution to overall conductivity.