Spectroscopic Evaluation of AlN/n-Si MIS Structures through Frequency-Driven Dielectric Characterization

This study presents a comprehensive spectroscopic and impedance-based analysis of a Au/Ti/AlN/n-Si metal-insulator-semiconductor (MIS) heterostructure, focusing on its frequency- and temperature-dependent electrical and dielectric behavior. The AlN interlayer, synthesized via hydride vapor-phase epitaxy (HVPE), was electrically characterized through admittance spectroscopy across a wide temperature range (100-350 K) and multiple frequencies (100, 500, and 1 MHz). Capacitance-voltage (<i>C-V</i>) and conductance-voltage (<i>G</i>/ω-<i>V</i>) measurements revealed strong dispersion effects, particularly at low frequencies and temperatures, where interfacial trap states and dipolar relaxation dominate the response. A negative capacitance behavior was observed under a reverse bias at low frequencies. Series resistance (<i>R</i> _s) analysis confirmed a transition from trap-limited to bulk-controlled conduction with increasing frequency. Dielectric parameters, including real and imaginary permittivity, loss tangent, AC conductivity, and electric modulus components, exhibited a thermally activated and frequency-sensitive behavior, highlighting the interplay between dipolar alignment, trap reconfiguration, and energy dissipation. These findings provide critical insight into the interfacial physics of AlN/Si systems and establish a robust framework for optimizing AlN-based MIS devices for high-frequency, high-temperature microelectronic and optoelectronic applications.