Influence of AlN passivation on thermal performance of AlGaN/GaN high-electron mobility transistors on sapphire substrate: A simulation study

•HEMT with AlN/SiN, demonstrates more excellent thermal performance than the conventional one.•The proposed dual SiN/AlN passivation HEMT (LG = 1 µm) TCAD simulation with self-heating model shown 60% improvement in drain current density and 63% improvement in transconductance.•All the devices (gate length, LG = 1 µm) switch from OFF- to ON-states using the voltage, VGS from −10 V to 0 V with fixed bias, VDS = 5 V. The ∼ 0.32 A/mm of drain current recover for the proposed device with 5 µm AlN from a conventional device because of the reduction of self-heating effects.•The AlN/SiN passivation HEMTs is the promising candidates for high power switching and also for microwave applications without significant reduction in device performance at high drain bias.