LAUSR

Gallium nitride (GaN) is typically grown on silicon carbide (SiC) or silicon (Si) substrates to form GaN-on-SiC or GaN-on-Si heterostructures; however, these systems often face fabrication challenges and significant lattice mismatch. Therefore, a comprehensive investigation of the GaN/SiC interface is essential for improving the structural stability and performance of GaN-on-SiC substrates. In this work, density functional theory calculations employing the plane-wave projector-augmented wave method and the generalized gradient approximation exchange-correlation functional, as implemented in Vienna Ab initio Simulation Package, were used to systematically investigate the interfacial structural stability of GaN-on-4H-SiC. Due to the complex stacking sequences of both GaN and 4H-SiC, atomic-scale compatibility plays a critical role in determining the interface stability. Our results show that GaN interfaced with the C-face of 4H-SiC exhibits lower total free energy and a reduced imaginary phonon fraction, indicating higher structural stability compared to the Si-face. Furthermore, tilting the GaN layer enhances dynamic stability, with 5° and 9° tilts reducing the imaginary component of the phonon spectrum by approximately 7.5%. These theoretical findings align well with recent experimental observations and provide valuable insights for interfacial engineering in high-performance GaN-on-SiC electronic devices.