The Effects of Temperature and Frequency on the Electrical and Dielectric Properties of Al2O3 Structure

Abstract

This study aims to investigate the behavior of aluminium oxide MOS capacitors under both high and low frequencies and to evaluate the changes in their electrical and dielectric properties due to temperature variations. The MOS capacitors were fabricated using a sputtering technique. To analyze the frequency effects, capacitance–voltage (C-V) and conductance-voltage (G-V) measurements were conducted at both high and low frequencies. Additionally, to study the influence of temperature, C-V and G-V measurements were carried out across a temperature range of 293 K to 393 K. From the experimental data, critical device parameters such as the Fermi energy level (E_F), barrier height (Φ_B), maximum electric field (Eₘ), and dielectric properties (ε′, ε″, and tan δ) were calculated. The deviations observed in the C-V curves were attributed to frequency-dependent interface states and boundary traps, highlighting the complex dynamics of charge trapping and surface states. Interestingly, both E_F and Φ_B were found to increase with temperature, a phenomenon that diverges from typical literature expectations and could be linked to the presence of interface defects. Moreover, at high frequencies, an increase in the dielectric loss factor (tan δ) and dielectric constants (ε′ and ε′′) was observed, indicating enhanced charge carrier mobility at elevated temperatures. This results in improved electrical conductivity and a reduction in resistance, which aligns with findings from previous studies. In summary, the strong sensitivity of aluminium oxide MOS capacitors to changes in temperature and frequency, along with significant variations in their dielectric properties, underscores their potential for use in temperature sensors, particularly within lower temperature ranges.