Microwave performance of AlGaN/GaN metal insulator semiconductor field effect transistors on sapphire substrates

• Published in: IEEE transactions on electron devices Vol. 48; no. 3; pp. 416 - 419
• Main Authors: Chumbes, E.M., Smart, J.A., Prunty, T., Shealy, J.R.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2001; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aluminum gallium nitrides; Devices; Electric potential; Field effect transistors; Gallium nitrides; Gates; MISFETs; Sapphire; Semiconductors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/16.906429

Metal-insulator-semiconductor field effect transistors (MISFETs) from surface-passivated undoped AlGaN/GaN heterostructures on sapphire were fabricated. Measured static output characteristics includes full channel currents (I/sub dss/) of roughly 750 mA/mm with gate-source pinchoff voltages of -10 V and peak extrinsic transconductancies (g/sub m/) of 100-110 mS/mm. Increased surface roughness resulting from a gate recess process to reduce the pinchoff voltage introduces gate leakage currents in the micro-amps regime. With evidence for reduced dc-to-rf dispersion from pulsed gate transfer characteristics, these devices at 4 GHz with 28.0 V bias generated maximum output power densities of 4.2 W/mm with 14.5 dB of gain and 36% power added efficiency.