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A dielectric constant of about 27 was demonstrated in the as deposited state of a 5 nm thick, seven layer nanolaminate stack comprising of Al2O3, HfO2 and HfTiO. All oxide films were evaporated using an Electron Beam Gun system on unheated p-Si substrate without adding O2. Pt was used as a gate electrode to form Metal-Insulator-Semiconductor capacitors. The effect of annealing temperature and time (till 950 oC and 10 min, respectively) in O2 atmosphere on chemical and electrical properties and characteristics of the dielectric stack was investigated. Annealing above 550 oC leads to formation of metallic silicate type transition layer. No increase of thickness of initial silicon oxide type interfacial layer (~0.8 nm) was observed as a result of oxidation of the Si substrate by diffused oxygen. The stack remains in an amorphous state at annealing temperature up to 950 oC. A quantum mechanical effective oxide thickness (EOT) of ~1.15 nm was achieved for non annealed stack. After annealing at 950 oC in an Oxygen atmosphere keff reduces to ~10 and EOT increases to 1.91 nm due to formation of 3.1 nm thick metallic silicate layer with dielectric constant of about 8.1. The limited values of leakage current density of about 8X10-7 and 1.0X10-4 A/cm2, respectively at electric field 2 and 5 MV/cm and maximum breakdown electric field of about 11.5 MV/cm were achieved after annealing at above 750 oC. Schottky emission, with barrier heights of 0.75 and 0.94 eV, respectively for as deposited and at 450 oC annealed films charge flow mechanism at an electric fields E<1 MV/cm was demonstrated. Space Charge Limited Current, which is characterized by the several trap states located in the energy range of 0.48-0.755 eV with densities of 6.8X1018 -2X1019 cm-3 is realized at electric fields above 1 MV/cm and annealing temperatures bellow 550 oC. At above 550 oC and at negative electric fields down to -6 MV/cm is established as modified Poole-Frenkel emission with Coulombic potential barrier of 1.37 to 1.42 eV. At E>-6 MV/cm, the transport mechanism is Fowler-Nordheim with a tunneling barrier height of about 2.5eV for structures annealed at above 750 oC. We demonstrate the absence of any type (trap assisted or direct) of tunneling conduction mechanisms in the investigated structures. |