A practical guide to electrical characterization of interface states: Case studies on SiC and GaN

SiC and GaN have garnered significant attention from both academia and industry due to their promising applications. However, interface states in these devices have become a critical performance-limiting factor. Furthermore, as novel device architectures continue to evolve, the characterization of interface states presents increasingly complex challenges. Among available techniques, electrical defect characterization methods have emerged as indispensable tools for investigating interface states due to their non-destructive nature, rapid measurement capabilities, cost-effectiveness, and ability to provide comprehensive parameters—including energy distribution, energy levels, and capture cross-sections. This tutorial highlights three widely used electrical characterization techniques for interface state analysis: capacitance-voltage (CV) profiling, the conductance method, and constant-capacitance deep-level transient spectroscopy (CC-DLTS). Each technique has demonstrated value within specific measurement ranges, and practical experience suggests that combining multiple approaches often yields the most reliable results. The discussion includes fundamental principles, implementation considerations, and case studies from actual device measurements, aiming to provide experimental researchers with practical guidance. With a focus on SiC and GaN, this guide seeks to offer actionable starting points for characterizing interface states, particularly for those new to these measurement techniques.