High-Efficiency AlGaAs/InGaAs/GaAs Pseudomorphic High-Electron-Mobility Transistors Using a Sub-Micron Deep-UV T-Shaped Gate Technology

A class-B AlGaAs/InGaAs/GaAs pseudomorphic power high-electron-mobility transistor (HEMT) with high power performance has been developed. A simple fabrication method of a sub-micron T-shaped gate using the deep-UV lithography technology with tri-layer photoresists is presented for improvement of efficiency and gain of a pseudomorphic power HEMT. The AlGaAs/InGaAs/GaAs multinary compound material structure of the HEMT was grown by the molecular-beam epitaxy (MBE). The HEMT with a gate width of 3.36 mm and a gate length of 0.5 mu m exhibits a transconductance of 383 mS/mm. The saturation drain-to-source current (IDss) is 265 mA/mm. At an operation frequency of 1.9 GHz, the device demonstrates a power-added efficiency (PAE) of 65% at a drain bias of 1.2 V and a quiescent drain current of 30 mA (3.37% I-DSS). The state-of-the-art power characteristics are, for the first time, achieved by the AlGaAs/InGaAs/GaAs pseudomorphic power HEMT using a sub-micron deep-UV T-shaped gate technology.