Exploring Oxide Semiconductors for Future Electronics

New materials widen the spectrum of properties available to device designers, enabling novel device designs and concepts to overcomeperformance limitations of current devices. In the first part of this talk, our work on perovskite complex oxide materials SrTiO3 and GdTiO3 will be presented.SrTiO3 is a high-K oxide material with a room temperature dielectric constant of ~300,it exhibits superconductivity, incipient ferroelectricity, and field-tunable dielectric constant while GdTiO3 is a ferrimagnetic Mott-Hubbard insulator. Recently, a two-dimensional electron gas (2DEG) with extremely high density of ~3 x 1014 cm-2 has been discovered at the heterointerface of SrTiO3/GdTiO3. This 2DEG density is highest among any known semiconductors and is interesting to realize high power electronic and tunable plasmonic devices.Our efforts to clarify the bandgap of GdTiO3, understandmobility limiting scattering mechanisms in SrTiO3and modulate large carrier concentrations in SrTiO3 and SrTiO3/GdTiO3 electronic devices will be presented.In the second part of the talk, I will briefly present our growth and device work on β-Ga2O3. β-Ga2O3is a wide-bandgap semiconductor material with a large energybandgap of ~4.9 eVand an expected breakdown electric field of ~8 MV/cm. Recent availability of large area bulk crystals of this material and demonstration of controlled doping makes it extremely promising for realizing high power semiconductor devices and for realizing vertical Nitride LEDs on transparent conducting substrates. I will present our initial growth results of β-Ga2O3 using Oxygen plasma Molecular Beam Epitaxy (MBE) & Ozone MBE, thermal characterization results of Ga2O3 bulk substrates and realization of Ga2O3Schottky diode & FET devices.