Si‐Doping Effects in AlGaN Channel Layer on Performance of N‐Polar AlGaN/AlN FETs

The nitrogen‐polar (N‐polar) AlGaN/AlN structure is expected to have higher carrier density than conventional metal‐polar AlGaN/GaN electronic devices, and the AlN substrate offers various advantages, such as high breakdown voltage and high‐temperature operation. Herein, a N‐polar AlGaN/AlN‐heterostructured field‐effect transistor (FET) with static FET characteristics is successfully fabricated. However, the drain current density, IDS, remains significantly small. This study aims to improve IDS by doping Si in the topmost AlGaN channel layer under various conditions.