Off-axis angle-induced anisotropy in second harmonic generation of hexagonal SiC/SiO₂ heterostructures

Defects at semiconductor heterointerfaces significantly degrade device performance, necessitating precise characterization. This study investigates second harmonic generation (SHG) anisotropy in off-axis hexagonal SiC/SiO₂ heterostructures to address this challenge. We develop a stratified model integrating nonlinear optical properties and geometric parameters (off-axis/azimuthal angles, polarization) to quantify SHG responses. Experimental validation confirms that increasing off-axis angles amplify angular-dependent SHG intensity distributions and sensitivity to specific orientations. Higher-order trigonometric terms dominate at larger angles, inducing pronounced anisotropy. These findings establish a theoretical framework for SHG in SiC gate oxides and advance defect-sensitive characterization techniques critical for optimizing high-power electronic devices.