Fabrication of densely packed arrays of GaN nanostructures on nano-imprinted substrates

We have grown GaN on patterned Si (1 1 0) substrates prepared using a nano-imprinting technique and investigated the influence of growth temperature and the nano-pattern on the morphology of the nanostructure. Although {1 1̄ 0 2} facets were preferentially formed as sidewalls at a growth temperature of 650 °C, {1 1̄ 0 0} facets became dominant at substrate temperatures above 700 °C. We found that closely packed hexagonal GaN nanostructures, which are quite promising for future high efficiency light emitting devices, can be formed by the correct choice of not only the alignment between the pattern and the in-plane crystalline orientation of the substrate but also the period of the triangular lattice array of Si nano-pillars. The formation of this unique structure can most probably be attributed to the self-inhibited growth of GaN on the sidewall facets.