Ordered versus random nucleation of InN islands grown by molecular beam epitaxy

Self-organization of two-dimensional InN nucleation islands into chains along the 11 2 ¯ 0 directions is revealed by scanning tunneling microscopy (STM). Such alignments occur on surfaces of InN(0001) with GaN insertion layers below, i.e., in InN/GaN/InN sandwich-structures. Increasing the temperature of nucleation leads to a reduced degree of ordering of the islands. For nucleation on surfaces of homogeneous and strain-free InN films, on the other hand, randomly distributed islands are observed. The possible origin of the island-chain formation is discussed.