High power InAlAs/InGaAs/InP-HFET grown by MOVPE

In this study we report the impact of an extended lateral gate-recess process in order to reduce the high electric field at the drain end of the gate and so to improve the breakdown performance. At first, we focus on an HFET fabricated by optical lithography (L/sub g/=0.7 /spl mu/m). The influence of various gate recess procedures on both the breakdown voltage and the drain saturation current is studied for various thickness of the barrier and supply layer, respectively. High power class A amplifiers exhibiting DC (RF) power capabilities in the range of 4-5 W/mm (0.5-0.75 W/mm) are presented. Then, we introduce a hybrid lithography process combining both optical and electron beam lithography. In this way a shorter gate (L/sub g/=0.35 /spl mu/m) is asymmetrically positioned in an extended lateral gate recess which enables both high breakdown voltage and increased cut off frequency.