Thermal simulation of laser lift-off AlGaN/GaN high electron mobility transistors mounted on AlN substrates

A finite element simulation was used to estimate the temperature rise of laser lift-off AlGaN/GaN high electron mobility transistors (HEMTs) mounted on AlN substrates via silicone elastomer under various conditions of power density on the transistor and for a range of elastomer thicknesses. The thermal response was compared to HEMTs fabricated on SiC and sapphire substrates. The maximum temperature of the transistor occurred in the gate area at a power level of 15 W, and was only 25 K higher than HEMTs fabricated on SiC. The transit time required for steady-state temperature of the flip-chip bonding device is in the range of a millisecond, which is faster than that of most power switch applications.