Maximizing Frequency Characteristics for THz SBD

This study establishes a universal design paradigm for GaAs‐based Schottky barrier diodes (SBDs), demonstrating that the synergistic optimization of the N‐layer doping concentration ( N d ) and thickness ( d N ) can maximize the dynamic cutoff frequency ( f cd ) for a given anode size. The research reveals that the key factor determining the device's frequency characteristics is not only the conventionally understood resistance–capacitance trade‐off but also the regulatory role of the capacitance modulation ratio ( C ratio ). The observed f cd peak essentially reflects the global optimal balance achieved under specific parameter combinations through the mutual coupling and competition among the internal C ratio , series resistance, and junction capacitance. Anode radius of 5, 4, and 3.5 μm shows that the corresponding optimal f cd reaches 3.6, 4.2, and 4.6 THz, respectively. Further analysis reveals that different anode dimensions require corresponding structural configurations of the device, with smaller anode dimensions necessitating higher N d and a thinner d N to achieve an optimized f cd . This work provides a solid theoretical foundation and a practical design pathway for the performance optimization of high‐frequency SBDs and other solid‐state devices.