InN nanocolumns grown by molecular beam epitaxy and their luminescence properties

• InN nanocolumns (NCs) grown by MBE without vertical diameter variation.
• Systematical study of InN NC growth at various TG, V/III ratios, and nucleation.
• Extremely intense PL is observed for the InN NCs, 2 orders stronger than thin films.
• PL power and T dependences indicate reduced defect and e− density & non-degenerate.

InN nanocolumns (NCs) without vertical diameter variation have been grown on GaN templates by molecular beam epitaxy. Growth temperature is the key parameter to obtain such shaped InN NCs. The density and surface distribution can be controlled by the V/III ratio and initial nucleation process. Intense photoluminescence (PL) is observed for the optimal InN NCs, about two orders of magnitude stronger than the InN epilayers. Superior excitation power and temperature dependence of the PL indicate significantly reduced defect density and residual electron density, non-degenerate property, and possibly suggest that there is a small or negligible level of electron accumulation at the smooth non-polar lateral surfaces.