Strain relaxation by pitting in AIN thin films deposited by metalorganic chemical vapor deposition

摘要

Strain relaxation mechanisms were investigated in epitaxial AIN layers deposited on (0001)-oriented AIN substrates by metalorganic chemical vapor deposition. It was revealed that epitaxial AIN layers under tensile strain can exhibit micro-cracks and nano-pits. A correlation existed between the amount of strain and number of pits in localized areas. Pit densities as high as 10~(10)cm~(-2) were observed in areas where the tensile strain reached ～0.4%, while unstrained areas of the film showed step flow growth. These nano-pits occurred as a strain relaxation mechanism and were not related to intrinsic defects, such as threading dislocations or inversion domains.