Optical properties of GaN nanorods grown by molecular-beam epitaxy; dependence on growth time

摘要

The growth and optical properties of GaN nanorods grown on Si(111) substrates by rf plasma assisted molecular-beam epitaxy are investigated by means of field emission scanning electron microscopy and photoluminescence measurements as a function of growth time. It is clearly demonstrated that the rate of growth of the nanorod diameter starts to increase after approx 90 min because of the coalescence of neighbouring nanorods. And the optical properties of the samples grown at a high growth rate are dramatically changed due to induced defects. The critical diameter for defect-free GaN nanorods is determined as below approx 140 nm under N-rich conditions.