Exploring the Effects of Barrier Thickness and Channel Length on Performance of AlGaN/GaN HEMT Sensors Using Off-the-Shelf AlGaN/GaN Wafers

AlGaN/GaN heterostructure high electron mobility transistors (HEMTs) have exceptional characteristics, but the structure-function relationship remains to be experimentally fully studied. This study presents a systematic experimental investigation of the synergistic effects of AlGaN barrier thickness and channel length on device performance, a critical gap in the literature, which is often dominated by simulation studies. We experimentally investigated how barrier thickness and channel length influence AlGaN/GaN FET performance. We observed that the transconductance increases with decreasing AlGaN barrier thickness for shorter channel lengths (15 and 50 µm) but showed the opposite trend for the longest channel length (100 µm). Meanwhile, the subthreshold swing was predominantly influenced by the barrier thickness, with thinner barriers generally yielding lower values. These results highlight the intricate interplay between barrier thickness and channel length, providing foundational insights into the design–performance relationship of AlGaN/GaN HEMTs and guiding the development of optimized sensors for different applications.