Temperature-dependent dielectric response and charge transport mechanisms in silicon nanowires for nanoelectronic and sensing applications

Abstract

Silicon nanowires (SiNWs) have emerged as promising candidates for next-generation nanoelectronic and energy devices due to their tunable physical properties and high surface-to-volume ratio. This work aims to investigate the dielectric response of SiNWs fabricated via metal-assisted chemical etching (MACE) of crystalline silicon in AgNO₃-based solutions, with particular emphasis on the influence of etching temperature over a fixed etching duration of 20 minutes. Impedance spectroscopy was employed across a broad frequency range (100 Hz–1 MHz) to extract key dielectric and electrical parameters, including complex impedance (Z*), dielectric loss (ε″), loss tangent (tan δ), and complex electric modulus (M*). The impedance behavior was accurately modeled using an equivalent circuit comprising a parallel resistor-CPE network in series with a resistance, revealing interfacial and bulk contributions. AC conductivity followed Jonscher's universal power law, with a temperature-dependent exponent s supporting a thermally activated transport mechanism governed by the non-overlapping small polaron tunneling (NSPT) model. Relaxation peaks in tan δ and M″ spectra indicated dipolar polarization and dual relaxation processes, respectively, while low-frequency suppression in M′ signified long-range charge mobility. The activation energy extracted from dielectric relaxation aligned closely with that obtained from DC conductivity, affirming the consistency of conduction and relaxation dynamics. These findings contribute to a deeper understanding of charge transport mechanisms in SiNWs and provide valuable insights for optimizing their performance in dielectric and nanoelectronic applications.