12 W/mm recessed-gate AlGaN/GaN heterojunction field-plate FET

A recessed-gate structure was introduced to improve transconductance (gm) and gain characteristics in AlGaN/GaN field-plate (FP) FETs. A maximum gm was improved from 130 to 200 mS/mm by introducing gate recess. Recessed FP-FETs exhibited 3-7 dB higher linear gain as compared with planar FP-FETs. A 1 mm-wide recessed FP-FET biased at a drain voltage of 66 V demonstrated 12.0 W output power, 21.2 dB linear gain, and 48.8 % power added efficiency at 2 GHz. To our knowledge, the power density of 12.0 W/mm is the highest ever achieved for GaN-based FETs.