Structural and Electrical Properties of Zr x Y1−x O y Nanocomposites for Gate Dielectric Applications

Abstract

The possibility of ultrathin ZrxY1−xOy films was investigated as a good gate dielectric structure for metal–oxide–semiconductor field-effect transistors (MOSFETs). Zr-doped Y2O3 nanocrystallites were synthesized by the sol–gel method. The nanocrystallite size was determined using the Scherrer equation and x-ray powder method from the main peak of the sample phase observed in x-ray diffraction patterns. Moreover, qualitative elemental analysis was performed by energy-dispersive x-ray spectroscopy. The nanocrystallite properties were characterized by scanning electron microscopy. The nanocrystallite morphology was determined by atomic force microscopy, showing that the grain size of the nanoparticles observed at the surface depends on the type of metal dopant and the annealing temperature. The capacitance–voltage and current density–voltage characteristics of the ZrxY1−xOy/Si structures were analyzed. The results indicate that the Zr0.1Y0.9Oy nanocomposite can be used as a good gate dielectric for next-generation MOSFET devices. The conduction mechanism in electrical fields below 0.25 MV/cm and the temperature range of 333 K < T < 423 K was found to be ohmic emission. A thermal excitation model is proposed to explain the ohmic current conduction mechanism.