Gate-controlled transport in GaN nanowire devices with high- k Si₃N₄ gate dielectrics

The high dielectric constant layer, Si₃N₄, was applied to the GaN nanowire devices. Single-crystalline wurtzite GaN nanowires prepared by the vapor-liquid-solid method were utilized to fabricate GaN nanowire field-effect transistor structures with Si₃N₄ and SiO₂ dielectric layers in order to investigate the effect of a high-k dielectric layer on the electrical characteristics of the GaN nanowires. By applying high-k gate dielectrics to GaN nanowire devices, higher drain current, lower subthreshold swing, and threshold voltage shift were obtained in spite of the slight degradation of the channel mobility due to the surface phonon scattering and the electrical scattering at fixed charges and trapped charges.