BaTiO3/SrTiO3 heterostructures for ferroelectric field effect transistors

Integration of ultrathin ferroelectric thin films with semiconductors is of interest for negative capacitance transistors that exhibit internal voltage gain, which may allow for scaling the supply voltage of low power circuits. In this study, BaTiO3 thin films were grown on doped SrTiO3 channels using molecular beam epitaxy. The BaTiO3 films are ferroelectric despite their low thickness (similar to 10 nm). Parallel plate capacitor devices exhibit anti-clockwise hysteresis, and a comparison with reference structures without BaTiO3 shows that the polarization in the BaTiO3 thin films is switchable and controls the charge density in the channel. Field effect transistors were fabricated to study the effect of ferroelectricity on the transistor characteristics. Anti-clockwise hysteresis and a shift in threshold-voltage are observed in the output characteristics of the transistors. These properties make these heterostructures a suitable system for studying negative capacitance effects. Published by AIP Publishing.