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

Abstract

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 μm 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 °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.