Thermal Sensitivity of Microwave Pseudomorphic High-Electron-Mobility Transistor Performance: Pre and Post Multilayer Technology

Herein, the temperature dependence of direct current (DC) and scattering parameters of GaAs pseudomorphic high-electron-mobility transistors (pHEMTs) before and after back-end-of-line process (multilayer technology) by evaluating corresponding equivalent-circuit models is reported on. The change of the relative sensitivity of the microwave performance with ambient temperature is evaluated using scattering parameter measurements and the corresponding equivalent-circuit models. The devices studied are two pHEMTs with the same 200 mu m gate width but manufactured using pre- and post-multilayer technology. The investigation is conducted under both cooled and heated conditions, through temperature variations from -25 to 125 degrees C. Although the thermal impact highly depends on the selected operating condition, the bias point is chosen to allow for a fair comparison between the transistor fabricated before and after multilayer technologies to the maximum. Similar patterns of thermal sensitivities are observed for the pre and post multilayer-manufactured devices but in the case of the multilayer device, the temperature effect is more pronounced.