Temperature and frequency dependent dielectric response in hybrid molecular beam epitaxy grown BaSnO₃ films

BaSnO₃ has recently gained significant attention as a promising candidate for transparent conducting and power electronic applications due to its high room temperature mobility and large carrier density when doped n-type. However, to date, no reports of dielectric properties for thin film BaSnO₃ have been produced. High quality, phase pure, epitaxial BaSnO₃ films were grown on Nb-doped SrTiO₃ (001) using a hybrid molecular beam epitaxy approach. A metal-insulator-metal capacitor structure was then fabricated using Pt top electrodes, and dielectric response was recorded using impedance spectroscopy. Dielectric constant and loss tangent were found to be 15 and 0.005, respectively, at 100 kHz and room temperature in 40-nm-thick films. Thickness was then varied to investigate the effect of dimensionality on dielectric properties as well as to determine the bulk-like response by isolating interface effects. We will discuss the dielectric constant and loss in BaSnO₃ films as a function of temperature, frequency, film thickness, and stoichiometry, as well as the effect of introducing Ti to create the BaSnO₃-BaTiO₃ solid solution.