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 (L G = 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, L G = 1 µm) switch from OFF- to ON-states using the voltage, V GS from −10 V to 0 V with fixed bias, V DS = 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. This work describes the self-heating effects on the behavior of AlGaN/GaN-based high-electron Mobility Transistors (HEMTs), which are grownon Sapphire substrate, using electro-thermal TCAD simulations. The proposed device, passivated with AlN/SiN, demonstrates more excellent thermal performance than the conventional one with SiN passivation due to the introduction of additional AlN on top of the device, which acts as a heat spreader. The electro-thermal simulations have carried out for different AlN thicknesses (0 µm to 25 µm), and the device with 5 µm AlN shows better performance compared to others. The proposed AlN/SiN stacked passivation HEMT shows a comparatively small lattice temperature of 418 K, whereas the conventional HEMT with SiN passivation shows 578 K. All the devices (gate length, L G = 1 µm) switch from OFF- to ON-states using the voltage, V GS from −10 V to 0 V with fixed bias, V DS = 5 V. The values of saturation drain current density (I DSS ) and transconductance (g m ) are 0.7 A/mm and 173 mS/mm for the proposed HEMT with 5 µm AlN considering the thermal simulation model. In contrast, the conventional device demonstrates those of 0.42 A/mm and 109 mS/mm, respectively. 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. Our study reveals that the AlN/SiN passivation HEMTs are a promising technology for high-power switching and microwave applications without significant reduction in device performance at high drain bias.