Physical and electrical properties of bilayer CeO2/TiO2 gate dielectric stack

• A bilayer gate dielectric stack of CeO2/TiO2 to study the dependency of film growth with varying annealing temperatures is proposed.
• The study demonstrates CeO2/TiO2 bilayer stack with comparable κ-value as that of HfO2 but with reduced leakage current density of 4 orders of magnitude.
• Schottky emission is the dominant leakage conduction mechanism of annealed CeO2/TiO2 stack due to thermionic effect of interface properties.

This study demonstrates a bilayer gate oxide structure of cerium oxide deposited via pulsed laser deposition and titanium oxide using conventional atomic layer deposition. Samples were deposited on p-type Si (100) substrate and exhibit interesting physical and electrical properties such that 600 °C annealed CeO2/TiO2 samples having κ-value of 18 whereas pure CeO2 deposited samples have dielectric constant of 17.1 with leakage current density of 8.94 × 10−6 A/cm2 at 1 V applied voltage. The result shows promising usage of the synthesized rare earth oxides as gate dielectric where ideal κ-value and significant reduction of the leakage current by 5 orders of magnitude is achieved.Leakage current conduction mechanism for as-deposited sample is found to be dominated by Poole–Frenkel (PF) emission; the trap level is found to be at 1.29 eV whereas annealed samples (600 °C and 800 °C) exhibited Schottky emission with trap levels at 1.45 eV and 0.81 eV, respectively.

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