RF-Enhanced Contacts to Wide-Bandgap Devices

This letter proposes a novel approach to fabricate high-performance heterostructure microwave devices with nonohmic contacts. The contact can be as-deposited or made by "shallow" low-temperature annealing to form a low-height Schottky barrier while preserving the two-dimensional electron-gas layer (2DEG) at the heterointerface. Coupling between the metal and the 2DEG occurs via two paths: dc current injects through the barrier leakage current and ac-current component injects through capacitive coupling. Contacts with resistive/capacitive coupling have low microwave impedance and enhance the heterostructure field-effect transistor's maximum oscillation frequency, output power, and power-added efficiency as compared to resistive ohmic contacts