Abstract
This study presents a model developed to analyze crack formation during the heteroepitaxial growth of ultrawide-bandgap (UWBG) III-N semiconductor films on Si substrates. It addresses the challenges of growing thick (~>1.5 μm) crack-free AlN films, which is crucial for integrating Si with UWBG semiconductors. Utilizing Griffith theory of brittle fracture and Mathews-Blakeslee theory of dislocations, the model predicts crack formation in 500-nm AlN films driven by in-plane tensile stress during the cool-down process after deposition. To prevent this, a ductile epitaxial interlayer is introduced to modify the tensile strain in the AlN film. This approach successfully demonstrates the epitaxial growth of 1.5-μm single-crystalline, crack-free AlN film on a Si substrate.
