Capacitance enhancement of Sm-doped hafnia MOS capacitors via cubic phase mediation

Abstract

The influence of Sm doping on hafnia (HfO₂) films has been systematically investigated by fabricating a Metal Oxide Semiconductor Capacitor (MOS Cap). The effect of structural transformation on the dielectric properties of Sm-doped hafnia films has been explored. Sm-doping was carried out on films using a cost-efficient spin-coating method. From structural studies, phase transformation was noted, with an increase in Sm doping concentration in HfO₂ films. X-ray photoelectron studies (XPS) indicated the passivation of oxygen vacancies in all the Sm-doped HfO₂ films. Uniform, non-porous, and crack-free films were observed from morphological studies. The electrical and dielectric properties were investigated by integrating Sm-doped hafnia films as an oxide layer in Metal Oxide Semiconductor Capacitor (MOSCap). At lower Sm doping concentrations, a reduction in the leakage current of the films was observed. Capacitance-voltage measurements in the dielectric studies indicated that the cubic phase stabilization significantly contributes to the rise of the capacitance. The impact of Sm doping on the MOSCap parameters such as oxide charges, dielectric permittivity, interface trap densities, and effective oxide thickness have been examined thoroughly. The detailed study provided in this work could help to explore next-generation dielectrics using economical techniques.