Properties of High-k Gate Dielectric LaAlO_3 Thin Films

The properties of a new high-k gate dielectric material LaAlO3 were investigated. LaAlO3 thin films were prepared on p-type Si substrates by using radio-frequency magnetron sputtering deposition. XRD analyses show that the films are amorphous even after annealed in O2 at 650℃ for 15min. The capacitance equivalent oxide thickness is 2.33nm with a leakage current of 3.73mA/cm2 and 5.32×10-4mA/cm2 at Vg=4+1V and -1V, respectively. The capacitance-voltage (C-V) characteristic curves show the existence of interface states in LaAlOs thin films. The hysteresis voltage in C - V curve is about 0.09V. The density of interface states calculated is about 8.35×1011cm-2. The current-voltage characteristic curves show that Pt/LaAlO3/Si thin film is conductive only under one voltage direction. The LaAlO3 thin film will be a promising high-fc gate dielectric for future ultra-large scale integrated devices.