Design and Optimization of AlGaN/AlN/GaN L-SBD for Radiofrequency Applications

This work presents a comprehensive investigation of the radiofrequency (RF) performance of lateral Schottky barrier diodes (L-SBDs) using an AlGaN/AlN/GaN heterostructure. The study aims to enhance carrier confinement and improve RF figures of merit by introducing a thin AlN interlayer between the AlGaN barrier and the GaN channel. The influence of AlN interlayer thickness (1-3 nm) on two-dimensional electron gas (2DEG) properties, current transport, capacitance, and dynamic behavior are systematically analyzed. Simulations were calibrated against experimental data to validate key physical models, including trap-assisted Schottky barrier modulation and plasma-induced surface degradation. The inclusion of an optimized 3 nm AlN interlayer enhances polarization-induced charge at the AlN/GaN interface, thereby increasing carrier concentration and mobility while mitigating alloy scattering. As a result, the device achieves a forward current of 630 mA/mm (∼9% improvement), a cutoff frequency (<i>f</i> _C) of 0.283 THz (∼14.11% increase), a dynamic conductance (<i>G</i> _d) of 310 mS/mm (∼10% enhancement), and a voltage sensitivity (β_V) of 1180 mV/mW (∼90% improvement) compared to the conventional L-SBD. An equivalent small-signal model is also developed to extract critical parameters, including series resistance, junction capacitance, and curvature coefficient. These results confirm that integrating a thin AlN interlayer significantly enhances the RF efficiency and sensitivity of GaN-based L-SBDs, making them promising candidates for high-frequency detector and microwave mixer applications.