Asymmetrical AlN nanopyramids induced by polar surfaces

摘要

Single crystalline wurtzite aluminum nitride (AlN) tetragonal nanopyramids were fabricated through thermal evaporation of aluminum in dilute ammonia flux. The nanopyramids have their tips growing along the [0110] direction and exhibit asymmetrical growth behavior along the ±[0001] directions. The formation mechanism was explained by a surface diffusion based model. The observation of the polar surface induced anisotropic growth in AlN nanostructures is expected to provide an insightful sample to investigate the microscopic crystal growth mechanism of AlN and other group III nitrides.