Studying of SiO2/capron nanocomposite as a gate dielectric film for improved threshold voltage

Abstract

In this study, SiO2 gate dielectric operation was improved using SiO2/capron nanocomposite. SiO2/capron nanocomposite was synthesized by the sol–gel method. The existence of two phases in the nanocomposite structure was revealed using energy dispersive spectroscopy. The formation of hydrogen bonds among SiO2 nanofillers and capron matrix was proved by Fourier transform infrared spectroscopy and thermogravimetric analysis. The fact resulted in the uniform dispersion of SiO2 nanoparticles within capron matrix and the formation of cross-linked network. Pure SiO2, pure capron, SiO2/capron nanocomposite dissolved in benzene alcohol and SiO2/capron nanocomposite dissolved in acid formic as the gate dielectric films were deposited on the p-type Si substrates. Atomic force microscopy showed a significant decrease in the average surface roughness of nanocomposite film (0.02 nm) compared to that of pure SiO2 and pure capron films (18.3 and 7.85 nm, respectively). The operation of deposited films as the gate dielectrics was compared by the current–voltage (I–V) measurements in the metal–insulator–semiconductor structure. Fabricated p-type Si field-effect-transistors demonstrated a great decrease in the leakage currents and the threshold voltages by decreasing the surface roughness of their dielectric films, because the charge transport is strongly associated with trap depth and carrier scattering effects in the semiconductor/dielectric interface. As a result, the threshold voltages were shifted toward downward and reached 1 V for transistor based on SiO2/capron nanocomposite dielectric film.