Characterization of N-polar AlN in GaN/AlN/(Al, Ga) N heterostructures grown by metal-organic chemical vapor deposition

摘要

In GaN/(Al, Ga) N high-electron-mobility transistors (HEMT), AlN interlayer between GaN channel and AlGaN barrier suppresses alloy scattering and significantly improves the electron mobility of the two-dimensional electron gas. While high concentrations of gallium were previously observed in Al-polar AlN interlayers grown by metal-organic chemical vapor deposition, the N-polar AlN (AlxGa1-xN) films examined by atom probe tomography in this study exhibited aluminum compositions (x) equal to or higher than 95% over a wide range of growth conditions. The also investigated AlN interlayer in a N-polar GaN/AlN/AlGaN/S. I. GaN HEMT structure possessed a similarly high x content.