Microwave Characterization and Comparison of Performance of GaAs Based MESFETs, HEMTs and HBTs Operating at High Ambient Temperatures

For the FIRST time microwave measurements at ambient temperatures up to 300°C have been performed on especially fabricated GaAs MESFETs, GaAs/AlGaAs HEMTs and HBTs, designed for continous operation at ambient temperatures up to 300°C with high reliability. A technology is presented which allows the realization of MESFET, HEMT and HBT device performance at elevated ambient temperatures. Ohmic and Schottky contacts have been realized with Ni-Ge-Au-Ni-W5-Si2-Au and LaB6-Au, respectively. These results open new possibilities for various applications of such transistors.