Structure, vibrations and electronic transport in silicon suboxides: Application to physical unclonable functions

Abstract

This work focuses on the structure and electronic transport in atomistic models of silicon suboxides (a-SiO_x; x = 1.3,1.5 and 1.7) used in the fabrication of a Physical Unclonable Function (PUF) devices. Molecular dynamics and density functional theory simulations were used to obtain the structural, electronic, and vibrational properties that contribute to electronic transport in a-SiO_x. The percentage of Si-[Si₁, O₃] and Si-[Si₃, O₁], observed in a-SiO_1.3, decrease with increasing O ratio. Vibrations in a-SiO_x showed peaks that result from topological defects. The electronic conduction path in a-SiO_x favored Si-rich regions and Si atoms with dangling bonds formed charge-trapping sites. For doped a-SiO_x, the type of doping results in new conduction paths, hence qualifying a-SiOx as a viable candidate for PUF fabrication as reported by Kozicki [Patent-Publication-No.: US2021/0175185A1, 2021].