Anisotropy of tensile stresses and cracking in nonbasal plane AlxGa1-xN/GaN heterostructures

作者：Young Erin C^*; Romanov Alexey E; Gallinat Chad S; Hirai Asako; Beltz Glenn E; Speck James S

来源：Applied Physics Letters, 2010, 96(4): 041913.

DOI：10.1063/1.3276561

• aluminium compounds
• atomic force microscopy
• cracks
• dislocations
• gallium compounds
• III-V semiconductors
• molecular beam epitaxial growth
• semiconductor growth
• semiconductor heterojunctions
• semiconductor thin films
• shear strength
• tensile strength
• wide band gap semiconductors

AlxGa1-xN films grown on nonpolar m {1100} and {1122} semipolar orientations of freestanding GaN substrates were investigated over a range of stress states (x < 0.17). Cracking on the (0001) plane was observed beyond a critical thickness in the {1100} oriented films, while no cracking was observed for {1122} films. Theoretical analysis of tensile stresses in AlxGa1-xN for the relevant planes revealed that anisotropy of in-plane biaxial stress for the nonpolar {1100} planes results in the highest normal stresses on the c-planes, consistent with experimental observations. Shear stresses are significant in the semipolar case, suggesting that misfit dislocation formation provides an alternative mechanism for stress relief.

• 出版日期2010-1-25