A long-term 3000-hour test under on-state conditions (V DS =25V, 6W/mm constant dissipated power) and off-state conditions (V DS =46V, V GS =-6V) on GaN/AlGaN/GaN HEMTs is presented. Trapping presence and hot-electrons effect are characterized by means of low-frequency techniques (lowfrequency noise measurements, transconductance frequency dispersion, gate-lag). The on-state stress shows the most important degradation. Since our measurements point out to the creation of traps in the gate-to-drain surface region during the stress, this degradation is ascribed to the effect of hotelectrons.

No abstract

This paper demonstrates a scalable electrothermal model for transient self-heating effects in trench-isolated SiGe heterojunction bipolar transistors (HBTs). The scalability of the thermal model has been investigated by considering pyramidal heat diffusion approximation between the heat source and the thermal ground. Three-dimensional thermal TCAD simulations have been carried out to obtain transient variations of the junction temperature and to extract the thermal impedance in the frequency domain. A recursive thermal network with scalable model parameters has been developed and added at the temperature node of the HBT compact model HiCuM. This network has been verified through numerical simulations and by low-frequency s-parameter measurements and found to be in excellent agreement for various device geometries.