Selective area growth of InN nanocolumns: Effect of lattice polarity

A weird effect of lattice polarity on the morphology of InN nanocolumns (NCs) via position- and lattice-polarity-controlled selective area growth (SAG) is demonstrated. In-polar and N-polar InN NCs grown on pillar-patterned GaN template were investigated experimentally and theoretically. Growth behaviors and morphology of InN NCs are analyzed, which exhibit different behaviors for opposite polarities, with pyramid growth front and inverted pyramid growth front for the In- and N-polarities, respectively. Theoretical calculation shows that the diffusion barriers of In and N adatoms on (0001) plane are 0.25 eV and 1.20 eV, respectively, which is about 2-fold larger than that of (0001) plane, resulting in opposite growth behaviors. The polarity inversion phenomenon in In-polar InN NCs provides another strong evidence for the polarity driven growth mechanism.