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, I DS , remains significantly small. This study aims to improve I DS by doping Si in the topmost AlGaN channel layer under various conditions.