Band alignment and interfacial properties of atomic layer deposited (TiO2) x (Al2O3)1-x gate dielectrics on Ge

(TiO2) (x) (Al2O3)(1-x) (x=0.7,0.8,0.9) gate dielectrics were deposited on Ge by atomic layer deposition using trimethylaluminium and Ti isopropoxide. The interfacial properties and band alignment were investigated by means of transmission electron microscopy (TEM) and X-ray photoemission spectroscopy. High-resolution TEM results show that the (TiO2)(0.8)(Al2O3)(0.2) film annealed at 500A degrees C is amorphous with sharp interface between (TiO2)(0.8)(Al2O3)(0.2) and Ge. The conduction-band offsets are enhanced from 1.04 to 1.40 eV with increasing Al content. Capacitance equivalent thickness of 15.8 for (TiO2)(0.9)(Al2O3)(0.1) gate dielectrics is achieved with a gate leakage current of 2.70x10(-5) A/cm(2) at V (g)=+1 V.