Short channel AlGaN/GaN MODFET's with 50-GHz f/sub T/ and 1.7-W/mm output-power at 10 GHz

Abstract

A thin barrier-donor layer of 200 /spl Aring/ was used to increase the active input capacitance and improve the extrinsic current-gain cutoff frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) of short-gate-length AlGaN/GaN MODFETs. 0.2-μm gate-length devices fabricated on such an epi-structure with sheet carrier density of /spl sim/8×10/sup 12/ cm/sup -2/ and mobility of 1200 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs showed a record f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> of 50 GHz for GaN based FETs. High channel saturation current and transconductance of 800 mA/mm and 240 mS/mm respectively were also achieved along with breakdown voltages of 80 V per μm gate-drain spacing. These excellent characteristics translated into a CW output power density of 1.7 W/mm at 10 GHz, exceeding previous record for a solid-state HEMT.