Theoretical investigations on the confinement properties of InAlN/GaN/AlGaN heterostructures employing Al

This study focuses on the InAlN/GaN/AlGaN heterostructures, initiating from polarization energy band tailoring engineering to establish a theoretical model. An AlxGa1-xN back-barrier is introduced to augment the confinement ability of the two-dimensional electron gas (2DEG) in conduction channel, enhance power output, and reduce leakage in the buffer layer. The primary investigation explores the impact of GaN channel layer’s thickness dGaN and the Al content x of the AlxGa1-xN back-barrier layer on the confinement properties and sheet density of 2DEG. It also examines the formation mechanisms of two-dimensional hole gas (2DHG) and the structural design requirements of back-barrier. Theoretical research indicates that as the x or dGaN increases, the confinement properties of the 2DEG significantly improve, provided a certain critical condition is met. Excessive x or dGaN induces the formation of 2DHG at the GaN/AlGaN interface. The findings demonstrate that maintaining the dGaN below a critical value, given a certain x, can enhance 2DEG confinement properties while suppressing 2DHG formation. This research offers a robust theoretical foundation for the development of GaN-based materials and HEMT device fabrication.