Nonresonant Terahertz Detector Based on Improved N‐Polar AlGaN/GaN Plasma Wave High‐Electron‐Mobility Transistors

The THz photoresponse of four different structures of N‐ and Ga‐polar AlGaN/GaN plasma wave high‐electron‐mobility transistors (HEMTs) has been comparatively investigated. Based on these results, an improved N‐polar plasma wave HEMT detector is proposed: an AlGaN cap layer is introduced in the standard N‐polar HEMT, so as to obtain a lower gate leakage current, thus improving the operating characteristics of plasma wave HEMT. The results show that the responsivity of the improved N‐polar HEMT obtains a significant improvement and as the Al component of AlGaN cap layer increases, the noise equivalent power of the improved N‐polar HEMT has also been optimized.