Structure and photoluminescence properties of epitaxially oriented GaN nanorods grown on Si(111) by plasma-assisted molecular-beam epitaxy

The authors show that vertically c-axis-aligned GaN nanorod arrays grown by plasma-assisted molecular-beam epitaxy are epitaxially oriented on Si(111) substrates and their crystal structure corresponds to a fully relaxed wurtzite lattice. At later growth stage, these GaN nanorods exhibit the tendency to coalesce into nanorod bundles. Low-temperature photoluminescence spectrum from 1-mu m-long GaN nanorods consists of intense exciton lines of strain-free bulk GaN and additional lines at similar to 3.21 and similar to 3.42 eV (Y-7 and Y-2). The Y-7 line is attributed to the excitons trapped along the dislocations at the boundaries of coalesced GaN nanorods, while the Y-2 line has its origin in the interface defects at the GaN/Si(111) interfaces. (c) 2006 American Institute of Physics.