Influence of A1N passivation on thermal performance of AlGaN/GaN high-electron mobility transistors on sapphire substrate: A simulation study

摘要

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 AIN/SiN, demonstrates more excellent thermal performance than the conventional one with SiN passivation due to the introduction of additional A1N 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 AIN/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 trans-conductance (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 AIN/SiN passivation HEMTs are a promising technology for high-power switching and microwave applications without significant reduction in device performance at high drain bias.