Characterization of the Electrical Properties of a Double Heterostructure GaN/AlGaN Epitaxial Layer with an AlGaN Interlayer

This paper proposes a double-heterostructure (DH) GaN/AlGaN epitaxial layer that contains an AlGaN interlayer. The electrical properties are characterized and compared with conventional single-heterostructure (SH) GaN/AlGaN epitaxial layers. The Hall effect measurement shows that the DH GaN/AlGaN epitaxial layer has a carrier mobility of 1815 cm² V⁻¹ s⁻¹, which is approximately 20.37% higher than the SH GaN/AlGaN epitaxial layer. The weak-beam dark-field images taken by transmission electron microscopy show that the AlGaN interlayer in the DH GaN/AlGaN epitaxial layer can block dislocations. The full widths at half maximum results show that there is no significant difference in the screw dislocation density between the SH and DH GaN/AlGaN epitaxial layers. However, the edge dislocation density and the overall internal stress in the DH GaN/AlGaN epitaxial layer are less than those in the SH GaN/AlGaN epitaxial layer. Finally, the physical mechanism of how edge dislocations impact the electrical properties of a DH GaN/AlGaN epitaxial layer is discussed.