Spontaneous formation of quantum height manganese gallium islands and atomic chains on N-polar gallium nitride(0001¯)

Deposition of manganese onto the gallium-rich, nitrogen-polar GaN(0001¯) surface results in the formation of quantum-height island structures. Two unique island heights differing by one atomic layer are observed, including 0.93 nm high islands which are unstable against the formation of 1.13 nm high islands. A row structure at the islands’ surface suggests a mixture of Mn and Ga, while growth of one-dimensional atomic chains at the surface of the stable 1.13 nm high islands indicates a strongly anisotropic diffusion. The observed behavior is consistent with a quantum size effect driven growth mechanism.