Comprehensive Dielectric Analysis of Schottky Devices with Cu-Doped DLC Interlayer: Temperature Effects and Polarization Mechanisms

Abstract

In this study, the temperature-dependent dielectric properties of a Cu-doped diamond-like carbon (DLC) interfacial-layered Schottky device (SD), fabricated by the electrochemical deposition method, were systematically investigated in terms of the dominant polarization mechanisms. Impedance measurements, performed over the temperature range of 80-410 K, were used to calculate the dielectric constant (e'), dielectric loss (e ''), loss tangent (tan(S)), ac conductivity (cac), and complex electric modulus (M*), including its real (M ') and imaginary (M '') components. The results reveal that all dielectric parameters exhibit three distinct behaviours within three temperature regions, namely low-temperature (LTs: 80-170 K), moderate-temperature (MTs: 200-290 K), and high-temperature (HTs: 300-410 K) regimes. This behavior indicates a pronounced sensitivity of the DLC interfacial layer to temperature. It was also observed that different polarization mechanisms, including dipolar, trapping-related, electronic, and space-charge polarizations, become dominant depending on the temperature and applied voltage range. Owing to the heterogeneous structure of the SD, the contribution of Maxwell-Wagner polarization, as a specific form of space-charge polarization, becomes particularly significant in the HTs region. Moreover, Cu doping leads to an increase in carrier density within the DLC layer, enhancing the tunneling probability and strengthening space-charge polarization through the increased availability of free carriers.