50-nm T-gate metamorphic GaAs HEMTs with f/sub T/ of 440 GHz and noise figure of 0.7 dB at 26 GHz

Abstract

. (2005) Index Terms-High-electron mobility transistor (HEMT), low noise, metamorphic, metamorphic high-electron mobility transistor (mHEMT), millimeter-wave imaging, nanometer gates, short gate.

Metal Insulator Gate Geometric HEMT: Novel Attributes and Design Consideration for High Speed Analog Applications

“…The speed of the device can be improved by shortening the gate length (L g ), but shortening the L g below sub-micrometer range requires various complex lithographic techniques [11][12][13][14][15][16][17][18][19][20][21][22]. This state-of-art performance requires careful attention to the technological details of gate formation, layer design, and MBE growth by multilevel resist process using e-beam lithography forming various metal insulator geometries like T-gate, Γ-gate etc.…”

T-gate geometric (solution for submicrometer gate length) HEMT: Physical analysis, modeling and implementation as parasitic elements and its usage as dual gate for variable gain amplifiers

“…Lithography has limited the gate length above sub-micrometer and thereby T-gate technology has emerged as a solution for implementing shorter gate length. Recently, 50-nm T-gate GaAs mHEMT [11] having upper gate/channel length of 300-nm have been reported with f T and f max as 440 GHz and 400 GHz respectively for GaAs based three terminal devices. This state-of-the-art performance widely in use these days [11][12][13][14][15][16][17], is attributed to careful attention given to the technological details of gate formation, layer design and MBE growth by multilevel resist process using e-beam lithography and reflow treatment.…”

Short Channel Analytical Model for High Electron Mobility Transistor to Obtain Higher Cut-Off Frequency Maintaining the Reliability of the Device

“…Among them the most common approaches are variation of doping concentration, variation of metal workfunction, gate-stack variation and the variation of gate-insulator geometries or field plates engineering . The T-gate geometry has generally been used for higher cut-off frequency performance due to the use of upper and lower gate electrode offering lower gate resistance and capacitance to the device [33][34][35][36][37][38][39][40][41][42][43][44][45]. The enhancement of these variations includes improved breakdown voltage, current voltage swing, linearity, efficiency, stability, reliability by suppressing phenomenon, namely surface traps effects, hot-carriers effects, current collapse, gate leakage, junction leakage, subthreshold leakage and DCto-RF dispersion.…”