Gate Length Influence on the Strain of the AlGaN Barrier Layer under the Gate in AlGaN/AlN/GaN HFETs at Different Temperatures

This study analyzes the impact of gate length on the strain of the AlGaN barrier layer beneath the gate in two AlGaN/AlN/GaN HFETs, measured through gate-source capacitance-voltage (C–V) curves and forward current voltage (I–V) curves at temperatures of 300, 350, 400, and 450 K. It is found that the strain in the device with a shorter gate length decreases as the temperature increases, whereas the strain in the device with a longer gate length shows an increasing trend. Furthermore, the observed variation in strain with temperature is linked to thermal dissipation from the gate electrode, an effect attributed to the gate length itself. These results suggest that the elevated-temperature performance of AlGaN/AlN/GaN HFETs can be improved through appropriate gate length design.